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  • Articles  (5,546)
  • Springer  (5,546)
  • American Association for the Advancement of Science (AAAS)
  • American Institute of Physics (AIP)
  • 1995-1999  (5,373)
  • 1940-1944  (173)
  • Technology  (5,546)
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  • Articles  (5,546)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 14 (1999), S. 2-19 
    ISSN: 1435-604X
    Keywords: Keywords: Corneal topography; Fluorescence; Holography; Interferometry; Moiré; Partial coherence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. Corneal topography has, due to developments in refractive surgery and contact lens fitting, become a widely used diagnostic tool. Many types of topographers have been introduced, but there is some confusion on classification and subsequent principal possibilities of the various devices offered to the practitioner. The purpose of the study reported here was to make an inventory of developed devices, analyse the basic principles and create a classification based on optical principles. A literature search was done using Medline, the IBM Patent Server, and references found in articles and patents. This search resulted in a variety of descriptions that could be classified into 12 groups according to their use of light source and light-matter interaction of which four groups have representatives on the commercial market. This classification can be used by researchers and practitioners to gain insight into the possibilities of a given device in relation to the desired application.
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  • 2
    ISSN: 1435-604X
    Keywords: Keywords: Interstitial laser coagulation; Laser applicator; Laser induced thermotherapy; Liver tumours; Nd-YAG laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. A newly developed diffusing laser applicator was examined for interstitial laser coagulation (ILC) of liver tumours. The applicator consisted of a matted quartz core and a quartz glass dome, also matted on its inner surface and sealed to the fibre. The applicator provided a homogeneous light intensity distribution over an active length of about 20 mm. Lesions were created in an ex-vivo porcine liver model using a Nd-YAG laser comparing the new diffusing tip with a Ringmode®-ITT applicator in order to find optimal laser parameters and damage thresholds. The lesions were investigated using macroscopic size measurement, volume calculation and histological examination (H&E, NADPH-dehydrogenase). The damage threshold of the diffusing tip was 6 W at 14 min exposure time whereas the Ringmode®-ITT applicator had its limit at 5 W and 12 min exposure. Comparing various exposure times showed that treatment over a time of more than 840 s did not significantly increase the lesion volume. At 5 W and 720 s the mean lesion volume was 6.9±1.1 cm3 with the diffusing tip and 6.3±0.6 cm3 with the Ringmode®-ITT applicator, both having a slight ellipsoidal shape. Hence, the created lesions were not significantly different for both applicators when the same laser parameters were applied. On the other hand, the new diffusing tip had a higher damage threshold and was therefore capable of producing maximal coagulation volumes of up to 7.9±0.5 cm3 at 5 W and 20 min. The experiments showed that lesions with a dimension of 31×22 mm can be achieved with the diffusing applicator which seem suitably sized for treating small human liver metastases in a single laser session.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 14 (1999), S. 62-66 
    ISSN: 1435-604X
    Keywords: Keywords: Laser myringotomy; Otitis media with effusion; Tympanic membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. A prospective comparative study was done to assess the validity of laser myringotomy (L-myringotomy) when compared to the insertion of ventilating tubes (VT). In 23 children with chronic otitis media with effusion, a VT was inserted in the left ear while a laser myringotomy was performed in the right ear by using the CO2 Sharplan 1030 laser. After a six month follow-up conducted during the winter months, the results with the laser myringotomy were equal to those in the left ear with the VT. During the follow-up period, three ears required additional laser myringotomy either for early closure or because of otitis media and the accumulation of effusion in the middle ear cavity. Nevertheless, the use of laser has the advantage that there is no foreign body in the ear, the tympanic membrane is closed after four to seven weeks, and since the procedure is very short, the time for anaesthesia is minimal.
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  • 4
    ISSN: 1435-604X
    Keywords: Keywords: Chorioallantoic membrane (CAM); Liposomes; Methylene blue; Ovarian cancer; Photodynamic therapy; Photosensitiser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. The disappointing results with either surgery alone and/or chemotherapy in the treatment of malignant ovarian tumours have led to an increased interest in additional treatment schedules. Photodynamic therapy (PDT), a modality involving the use of a photosensitising drug and activating light, is being used increasingly as a local treatment for neoplastic lesions. The synthesis and evaluation of new photosensitisers for the treatment of gynaecological lesions and malignancies continues to be an active area of investigation for proper application of the photodynamic process in the gynaecological field. The effect of PDT using methylene blue (free and combined with liposomes) as a photosensitiser for treating human ovarian malignant tumours cultivated on the chorioallantoic membrane was evaluated. Two days after PDT, the treated implanted tumours were markedly decreased in size. Areas of necrosis with black coloration, dryness and eschar formation were observed. Five days after PDT, tumour remission was clearly observed in all the treated tumours. Photodynamic therapy using methylene blue (aqueous and coupled with liposomes) is effective for treating the ovarian malignancies and it will be capable of achieving complete eradication of visible tumours in patients with superficial lesions.
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  • 5
    ISSN: 1435-604X
    Keywords: Keywords: Aminolaevulinic acid; Dermatology; Photodynamic therapy; Photosensitisation; Protoporphyrin IX; Skin lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. The method of surface-detected fluorescence has been used to monitor the emission intensity from 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) in lesions and corresponding adjacent normal skin. Three types of lesions were examined: psoriatic plaques, actinic keratosis and basal cell carcinoma. This study included a total of 14 human volunteers on whom ALA-induced PpIX formation and clearance was monitored for a total of 48 h post-ALA application. Both an ALA dose-ranging study, as well as a comparison of results between normal and lesional tissue at a fixed ALA dose, were carried out. For the dose range examined (10–30%), there was no ALA dose dependency of the PpIX fluorescence for any of the lesions tested. Although all three lesions tested did show enhanced PpIX fluorescence as compared with normal skin, there was considerable lesion-to-lesion variability. Thick psoriatic plaques seem to give longer PpIX retention times than those of thin lesions. Limitations of the surface-detected fluorescence methodology are discussed.
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  • 6
    ISSN: 1435-604X
    Keywords: Keywords: Interstitial laser therapy; Liver; Perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. Interstitial laser Doppler flowmetry was used to measure the effect of interstitial laser-induced thermotherapy on local blood perfusion in normal rat liver in the peripheral treatment region elevated to hyperthermic temperatures. The Nd:YAG laser emitting at 1064 nm was utilised as heat generation source. The plane-cut tip of an optical fibre was placed in the middle of the exteriorised left liver lobe. Blood perfusion and temperature were measured in the liver parenchyma 4 mm from the laser fibre. The temperature at the location of the liver temperature sensor was maintained at 41 or 44°C during 30 min by regulating the power of the heating laser. The laser Doppler signal was recorded during and after heat treatment, for a total time of 60 min. At 41°C, a significant increase in perfusion up to 1.3 times the initial value was observed 2–16 min after start of treatment. At 44°C, perfusion decreased continuously during and after treatment, and was significantly different from control 40 min after start of treatment. The results may be valuable in assessing the thermal response of tissues surrounding the target in interstitial laser-induced thermotherapy of liver tumours during conditions of normal blood flow.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 14 (1999), S. 168-174 
    ISSN: 1435-604X
    Keywords: Keywords: Endodontics; Laser ablation; Nd:YAG laser; Picosecond laser; Root canal therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . The interaction of picosecond laser radiation with human dental tissue was investigated in this study, in order to determine the ablation rates and the surface characteristics of the dentine by using scanning electron microscopy (SEM). Dentine ablation was performed by using tooth sections of different thicknesses (0.5–2.0 mm). Dental tissue samples were irradiated in air with the fundamental wavelength and first harmonic of a regenerative amplifier Nd:YAG laser system, at 1064 nm and 532 nm, respectively, with a pulse duration of 100 ps and a pulse repetition rate of 10 Hz. The results showed very clean craters surrounded by minimum melting of the surface of dentine when the 1064 nm pulses were used. In contrast, when the first harmonic 532 nm pulses were used, the SEM examinations revealed cracks and melting of dentine with irregular surface modification. Consequently, it seems that cleaning and shaping of the root canal walls during endodontic therapy with the picosecond Nd:YAG laser application may be possible in the future. The, as yet unexplored, field of the picosecond laser interaction with hard dental tissue is expected to be a potential alternative for powerful laser processing of biomedical structures.
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  • 8
    ISSN: 1435-604X
    Keywords: Keywords: Chlorins; Firing; Janus green B; Methylene blue; Neuron; Photodynamic effect; Photoheme; Photoporphyrin IX; Photosens; Photosensitisers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . The study of single neuron response to photodynamic effect provides a means for the study of the dynamics of cytotoxic events leading to cell death and allows comparison of the phototoxicity of different photosensitisers. Isolated crayfish stretch receptor neurons were photosensitised for 30 min, then irradiated with a He-Ne laser (632.8 nm; 0.3 W/cm2) until irreversible firing cessation. The dynamics of neuron firing frequency were continuously recorded throughout. The following photosensitisers were studied: methylene blue, janus green B, protoporphyrin IX, chlorins e 6 and p 6, haematoporphyrin derivative (Photoheme) and sulphonated aluminium phthalocyanine (Photosens). Nerve cells were found to be insensitive to either He-Ne laser irradiation or photosensitisation alone, but very vulnerable to the photodynamic effect: neurons changed firing rate and died at nanomolar concentrations of photosensitisers. The dynamics of neuron responses was found to depend on photosensitiser type and concentration. The current approach provides a means of evaluation of initial threshold cell membrane alteration and cytotoxic events leading to cell death. The dependence of firing acceleration rate and neuron lifetime on photosensitiser concentration additionally allowed comparison of efficiencies of different photosensitisers. Photosens, Photoheme and chlorin p 6 were found to be the most potent photosensitisers: neurons responded to their photodynamic effects at concentrations as low as 1–5 nM.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 14 (1999), S. 73-80 
    ISSN: 1435-604X
    Keywords: Keywords: Biocides; Disinfection; Laser; Optical fibre
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. In order to set up a disinfection protocol, the tip of the optical fibre of an Nd-YAP laser, λ=1.34 μm, was contaminated in vitro with: Mycobacterium smegmatis (CIP 7326), Candida albicans (ATCC 2091), Bacillus stearothermophilus (ATCC 7953) or Streptococcus sanguis (ATCC 10556). It was then treated with various biocidal solutions, Septinol® V, glutaraldehyde 2%, ethanol 95° and NaOCl 6%, using one of two protocols: 10 s of contact, or 5 s of contact followed by 5 s of wiping. The latter technique proved to be the most effective. Whatever the biocidal solution used, all the bacteria adhering to the fibre were eliminated. The protocol was checked in vivo in the canals of 10 teeth presenting root canal infections. No bacteria withstood the treatment with Septinol® V. This treatment does not alter the qualities and performance of the fibre as far as light transmission is concerned.
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  • 10
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    Lasers in medical science 14 (1999), S. 105-108 
    ISSN: 1435-604X
    Keywords: Keywords: Glaucoma, open angle; Intraocular pressure; Laser surgery; Trabecular meshwork; Trabeculoplasty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. A randomised prospective study was carried out to determine whether diode laser trabeculoplasty (DLT) is as effective as argon laser trabeculoplasty (ALT) in the control of primary open angle glaucoma (POAG). Forty eyes of 40 patients with uncontrolled intraocular pressure (IOP) despite maximum topical medication were entered into the study. Twenty eyes received DLT, spot size 100 μm, exposure time 0.2 s, mean power 1034 (±56.4) mW. Twenty eyes received ALT, spot size 50 μm, exposure time 0.2 s, mean power 528 (±44.7) mW. They were reviewed at 2 h, 2 and 8 weeks, and 3, 6, 12, 18 and 24 months after laser treatment. Two eyes were withdrawn from the DLT group and four from the ALT group because of uncontrolled IOP during follow-up. Of the remaining eyes in the trial, mean IOP reductions for DLT and ALT, respectively, were: 6 months 7.42 (±2.36) mmHg and 6.36 (±2.3) mmHg; 12 months 7.02 (±2.6) mmHg and 6.28 (±2.2) mmHg; 18 months 6.86 (±2.8) mmHg, 5.98 (±2.02) mmHg; 24 months 6.50 (±2.72) mmHg, 5.92 (±2.02) mmHg. There was a significant reduction in each laser group when IOP at each stage was compared with baseline (p〈0.001) (paired Student's t-test), but no significant difference between the two groups. In the ALT group peripheral anterior synechiae developed in four eyes and post laser pain in seven eyes. These complications were not noted following DLT. We conclude that DLT and ALT are equally effective in IOP control, but DLT is associated with less anterior segment inflammation.
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  • 11
    ISSN: 1435-604X
    Keywords: Keywords: Colour-coded duplex sonography; Laser induced thermotherapy; Minimal invasive therapy; Recurrent breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. The effect of laser-induced thermotherapy (LITT) as a palliative method for treatment of patients with local recurrence of breast cancer is investigated. This report describes the use of interstitial laser photocoagulation to manage such lesions. The interstitial laser applications were performed in seven women with locally recurrent breast carcinoma on the chest wall after mastectomy. All patients had been heavily pretreated with conventional modes of therapy (radiotherapy, chemotherapy, hormonal therapy, surgical resection). A Nd:YAG laser with a wavelength of 1064 nm was used to heat the lesions. Heat expansion was controlled digitally and monitored by ultrasonography and colour-coded duplex sonography (CCDS). In five women this minimally invasive method enabled the precise coagulation of the subcutaneous tumour without destruction of the skin or ulceration, although these areas had been pretreated by irradiation up to 60 Gy. In two patients with extensive multiple metastases and with skin infiltration, secondary skin ulceration and delayed healing was observed. For palliative reasons, LITT under CCDS guide can aid in local control of chest wall recurrence following mastectomy in selected patients.
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  • 12
    ISSN: 1435-604X
    Keywords: Keywords:Candida albicansCandidosis; Hyphae; Lethal photosensitisation; Toluidine blue O; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. Oral infections due to Candida albicans are a common occurrence in patients with acquired immunodeficiency syndrome (AIDS). The purpose of this investigation was to determine whether the yeast and hyphal forms of the organism could be killed using the light-activated antimicrobial agent toluidine blue O (TBO). Three variables were investigated: TBO concentration, laser light dose and pre-irradiation time (PIT). Irradiation with light from a helium neon (HeNe) gas laser used in conjunction with the photosensitiser TBO resulted in substantial kills of both the yeast and hyphal forms. Killing was light dose-dependent with 42 J being the most effective dose. The optimum PIT for the yeast form was 5 min, whereas killing of the hyphal form was not affected by PIT. The results of this study have shown that both forms of C. albicans are susceptible to lethal photosensitisation using TBO in conjunction with HeNe laser light, suggesting the possibility that this approach could be useful for eliminating the organism from diseased lesions in vivo.
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  • 13
    ISSN: 1435-604X
    Keywords: Keywords: Beamsplitter; Liver; Metastases; Nd:YAG; Tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . Simultaneous application of multiple fibres could increase the volume of coagulation produced with interstitial laser photocoagulation (ILP) for solid tumours. To take full advantage of the presumed synergistic thermal effect between the fibres, the optimal combination of laser power and distance between the fibres was investigated. Four fibres with a cylindrical diffusing tip of 2 cm length were used, coupled to an optical beamsplitter for Nd:YAG light (four channels, maximal variation 9.5%, transmission 〉85%). The distance between the fibres was 1, 1.5, 2, 2.5 , 3 or 4 cm with a power output of either 4, 5, 6 or 7 W/fibre; energy per fibre was constant at 1800 J by adjusting exposure time. After laser application, dimensions of the coagulated lesions were measured. The optimal mutual fibre distance was 2 cm ( p〈0.01) at all power levels. This resulted in lesions with a mean (SD) volume of 44.5 (2.1) cm3 and a largest diameter of 5.1 (0.4) cm at 7 W/fibre. Smaller distances between the fibres resulted in smaller lesions with central carbonisation, whereas larger distances resulted in four separate zones of coagulation. It was concluded that simultaneous application of four interstitial fibres may result in a considerable increase of volume of coagulation. Fibre position and mutual fibre distance determines whether synergism of the coagulative effect occurs.
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  • 14
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    Lasers in medical science 14 (1999), S. 244-246 
    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
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  • 15
    ISSN: 1435-604X
    Keywords: Keywords: Diffuser; Emission profile; Fluorescence imaging; Interstitial laser photocoagulation; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . Cylindrical light diffusers are commercially available for clinical applications such as photodynamic therapy (PDT) and interstitial laser photocoagulation (ILP). A fluorescence imaging technique has been used to quantify the light distribution produced by each of six different diffuser fibres. The light distribution produced by each device was found to depend on the distance the light propagated in the fluorescent dye solution. At a distance of 1 mm from the diffuser midline, the measured profiles were found to be consistent with published results obtained in air at a similar distance. The three devices intended for PDT utilised scattering particles and reflectors in their construction. The profiles produced by these applicators revealed peaks that were attributed to the reflectors located at their distal tips. By comparison, the two etched ILP fibres displayed either a strong modulation in the profile due to non-uniform etching or a predominant forward peak associated with the conical shape of the tip. We conclude that it is important to take into account the forward-directed light emitted by the diffusers when considering clinical applications using these devices.
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  • 16
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    Lasers in medical science 14 (1999), S. 297-306 
    ISSN: 1435-604X
    Keywords: Keywords: Bioheat transfer equation; ILP; In vivo; LITT; Photocoagulation; Rate kinetics; Temperature distribution; Thermal lesion size; Thermotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . An investigation of the temperature response and growth of thermal lesions resulting from in vivo, interstitial laser photocoagulation at long exposures was conducted to assess extended lesion growth characteristics and test the applicability of first order unimolecular rate kinetics (Arrhenius theory) to thermal lesion growth. Irradiations were performed in vivo in rabbit muscle using a continuous 805 nm diode laser source operating at 1.0 W coupled to an optical fibre with a precharred tip (i.e. point heat source). Temperature responses were measured using a linear array of five microthermocouples. Each temperature–time profile was fitted to a solution of the Weinbaum–Jiji bioheat transfer equation (W–J BHTE). Lesions were resected 48 h post-irradiation and the necrosis boundaries were determined histologically. Numerical integration of the Arrhenius damage integral using temperature–time data at the lesion boundary produced corresponding pairs of activation energy and pre-exponential factor (E a, α) consistent with reported values for various other end-points and tissue types. Lesion radii were 6.0±0.6, 8.7±0.4 and 9.7±0.5 mm for 10, 20 and 30 min irradiations respectively. Thermal lesion growth predicted from Arrhenius theory was consistent with experimental results and is non-asymptotic by 30 min. Thermal parameters generally assumed to be constant when solving the W–J BHTE were found to vary with radial distance from the source, presumably due to a temperature dependence.
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  • 17
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    Research in engineering design 11 (1999), S. 20-30 
    ISSN: 1435-6066
    Keywords: Key words:Convex robustness – Monte Carlo simulation – Probabilistic design – Robust design methodology – Robust process optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: Critical design decisions are commonly made throughout the product development process assuming known material and process behavior. However, stochastic variation during manufacture can inadvertently result in inferior or unacceptable product performance and reduced production yields. Stochastic simulations have been developed to estimate the end-use performance distribution prior to the commitment of hard tooling. This article proposes a definition for integrated product and process robustness, and extends existing stochastic methods to model the important role of the manufacturing flexibility in elimination of defects and product optimization. The goal is to enable the designer to understand and account for not only the negative effects of manufacturing variation, but also the positive impact of manufacturing flexibility wherein instantaneous corrections in the manufacturing process can frequently improve the product quality and eliminate flaws in the product design. Then, a methodology is introduced and contrasted with conventional development methods in the evaluation of best practices for development of a molded plastic component.
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  • 18
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    Research in engineering design 11 (1999), S. 31-44 
    ISSN: 1435-6066
    Keywords: Key words:AI as text – Design knowledge – Design support – Distributed design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: Currently, designers are faced with searching through a ‘sea’ of on-line knowledge to support their decision making activities. This paper describes WebCADET, which is a reimplementation of the stand-alone CADET – a Knowledge-Based System (KBS) for product design evaluation. WebCADET aims to provide effective and efficient support for designers during their searches for design knowledge. WebCADET uses the ‘AI as text’ approach, where KBSs can be seen as a medium to facilitate the communication of design knowledge between designers. The development of WebCADET to include practical support via World Wide Web-based functionality, which illustrates the potential of the ‘AI as text’ approach, is described in the paper.
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  • 19
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    Research in engineering design 11 (1999), S. 116-132 
    ISSN: 1435-6066
    Keywords: Key words:Axiomatic design – Complexity – Design axioms – Periodicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: One of the topics that has received the attention of mathematicians, scientists and engineers is the notion of complexity. The subject is still being debated, as it lacks a common definition of complexity, concrete theories that can predict complex phenomena, and the mathematical tools that can deal with problems involving complexity. In axiomatic design, complexity is defined only when specific functional requirements or the exact nature of the query are defined. Complexity is defined as a measure of uncertainty in achieving a set of specific functions or functional requirements. Complexity is related to information, which is defined in terms of the probability of success of achieving the Functional Requirements (FRs). There are two classes of complexity: time-dependent complexity and time-independent complexity. There are two orthogonal components of time-independent complexity, i.e., real complexity and imaginary complexity. The vector sum is called absolute complexity. Real complexity of coupled design is larger than that of uncoupled or decoupled designs. Imaginary complexity can be reduced when the design matrix is known. As an example of time-independent imaginary complexity, the design of a printing machine based on xerography is discussed. There are two kinds of time-dependent real complexity: time-dependent combinatorial complexity and time-dependent periodic complexity. Using a robot-scheduling problem as an example, it is shown that a coupled design with a combinatorial complexity can be reduced to a decoupled design with periodic complexity. The introduction of periodicity simplifies the design by making it deterministic, which requires much less information. Whenever a combinatorial complexity is converted to a periodic complexity, complexity and uncertainty is reduced and design simplified.
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  • 20
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    Research in engineering design 11 (1999), S. 158-171 
    ISSN: 1435-6066
    Keywords: Key words:Closure – Fixation – Organisation – Search
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: A study was conducted of what influenced solution search activity in three design organisations. The influences were analysed in terms of how they affected search, whether their effect tended to be conservative or innovative, and the directness of the evidence they provided. Overall, the environment was found to provide more innovative influences than conservative ones. Innovative influences were mostly connected with the triggering of search activity, while conservative influences were mostly linked with restricting the search space of potential solutions. Also, search candidates were often evaluated in terms of their associations rather than their intrinsic merits, and ultimately this makes human judgment an essential component of search and evaluation activity. Finally, the environment provides many ‘seeds’ for effects like design fixation and functional fixedness but also provides strong incentives to positively avoid these effects.
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  • 21
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    Research in engineering design 11 (1999), S. 145-157 
    ISSN: 1435-6066
    Keywords: Key words:Key characteristics, Process verification, Quality monitoring – Variation modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: To maximize product quality, a product design team selects concepts and dimensions to minimize a product’s sensitivity to variation. However, even for the most robust products, it is rarely possible to transition a product into production without encountering any variation-related problems. In a complex product, it is not economically or logistically feasible to control and/or monitor the thousands of tolerances specified in a product’s drawing set. To address this problem, many organizations are using Key Characteristic (KCs) methods to identify where excess variation will most significantly affect product quality, and what product features and tolerances require special attention from manufacturing. As simple as this principle seems, most companies struggle to effectively implement KC methods because no quantitative methods to prioritize KCs exist. This paper develops a mathematical definition of a KC based on a variation propagation model. In addition, it develops a quantitative effectiveness measure used to prioritize where verification, variation reduction, and on-going monitoring should be applied. The effectiveness measure incorporates the cost of control, the benefit of control, and the expected change in process capability. The methods are illustrated using an automotive door assembly.
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  • 22
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    Mathematics of control, signals, and systems 12 (1999), S. 24-61 
    ISSN: 1435-568X
    Keywords: Key words. Polynomial J-spectral factorization, Two-variable polynomial matrix, Quadratic differential form, Dissipativity, Pick matrix.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. In this paper new algorithms are developed for J-spectral factorization of polynomial matrices. These algorithms are based on the calculus of two-variable polynomial matrices and associated quadratic differential forms, and share the common feature that the problem is lifted from the original one-variable polynomial context to a two-variable polynomial context. The problem of polynomial J-spectral factorization is thus reduced to a problem of factoring a constant matrix obtained from the coefficient matrices of the polynomial matrix to be factored. In the second part of the paper, we specifically address the problem of computing polynomial J-spectral factors in the context of H ∞ control. For this, we propose an algorithm that uses the notion of a Pick matrix associated with a given two-variable polynomial matrix.
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  • 23
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    Mathematics of control, signals, and systems 12 (1999), S. 80-120 
    ISSN: 1435-568X
    Keywords: Key words. Hidden Markov models, Realization, Finite-state Markov process.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. If {X t} is a finite-state Markov process, and {Y t} is a finite-valued output process with Y t+1 depending (possibly probabilistically) on X t, then the process pair is said to constitute a hidden Markov model. This paper considers the realization question: given the probabilities of all finite-length output strings, under what circumstances and how can one construct a finite-state Markov process and a state-to-output mapping which generates an output process whose finite-length strings have the given probabilities? After reviewing known results dealing with this problem involving Hankel matrices and polyhedral cones, we develop new theory on the existence and construction of the cones in question, which effectively provides a solution to the realization problem. This theory is an extension of recent theoretical developments on the positive realization problem of linear system theory.
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    Mathematics of control, signals, and systems 12 (1999), S. 143-166 
    ISSN: 1435-568X
    Keywords: Key words. Asynchronous systems, Total asynchronism, Regular desynchronization, Global stability, Nonlinear discrete-time systems, Hopfield neural nets.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. This paper proves a global stability result for a class of nonlinear discrete-time systems that are subject to regular desynchronization, also known as total asynchronism. The class of systems studied has its origins in a discrete-time neural net model. The techniques used are of interest in terms of the use of a Lyapunov function for the study of convergence of asynchronous nonlinear dynamical systems and also in terms of applications to neural networks. In the latter context, the main result of this paper strengthens a result of an earlier paper on neural networks, and shows that a class of discrete-time continuous-valued neural nets of the Hopfield type displays global convergence properties even when there exists total asynchronism in the updating of neuron states.
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    Mathematics of control, signals, and systems 12 (1999), S. 196-218 
    ISSN: 1435-568X
    Keywords: Key words. Infinite-dimensional system, Time-varying system, Mild evolution operator, Riccati equation, Optimal control problem.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. In this paper we consider time-varying linear systems on Hilbert spaces and study the linear quadratic optimal control problem with an indefinite performance criterion over an infinite time interval. An example shows that in contrast to the finite-dimensional situation, in general, the solvability of the optimal control problem does not imply the solvability of the associated integral Riccati equation. Using an operator theoretic approach towards the time-varying integral Riccati equation, we derive equivalent conditions for the solvability of both problems.
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    Mathematics of control, signals, and systems 12 (1999), S. 245-269 
    ISSN: 1435-568X
    Keywords: Key words. Families of nonlinear systems, Robust stabilization, Nonsmooth state feedback.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. In this paper we consider a class of parameterized families of nonlinear systems which cannot be robustly asymptotically stabilized by means of C 1 feedback. We construct C 0 state feedback laws which are smooth away from the origin and which robustly asymptotically stabilize these families of systems. We then show that, in some cases, the regularity of the obtained robust asymptotic stabilizers is “maximum” in the sense that the considered families of systems do not admit any Lipschitz continuous robust asymptotic stabilizer.
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    Mathematics of control, signals, and systems 12 (1999), S. 295-305 
    ISSN: 1435-568X
    Keywords: Key words. Orthonormal basis functions, Continuous-time, Fourier series, Lp convergence.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. In this paper, model sets for linear-time-invariant continuous-time systems that are spanned by fixed pole orthonormal bases are investigated. These bases generalize the well-known Laguerre and two-parameter Kautz cases. It is shown that the obtained model sets are everywhere dense in the Hardy space H 1(Π) under the same condition as previously derived by the authors for the denseness in the (Π is the open right half plane) Hardy spaces H p(Π), 1〈p〈∞. As a further extension, the paper shows how orthonormal model sets, that are everywhere dense in H p(Π), 1≤p〈∞, and which have a prescribed asymptotic order, may be constructed. Finally, it is established that the Fourier series formed by orthonormal basis functions converge in all spaces H p(Π) and (D is the open unit disk) H p(D), 1〈p〈∞. The results in this paper have application in system identification, model reduction, and control system synthesis.
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    Mathematics of control, signals, and systems 12 (1999), S. 307-345 
    ISSN: 1435-568X
    Keywords: Key words. Robust control, Nonlinear control, Queueing server, Hamilton–Jacobi equation, Traffic signals, Storage function, Bicharacteristics, Boundary dynamics.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics , Technology
    Notes: Abstract. This paper extends previous work of Ball et al. [BDKY] to control of a model of a simple queueing server. There are n queues of customers to be served by a single server who can service only one queue at a time. Each queue is subject to an unknown arrival rate, called a “disturbance” in accord with standard usage from H ∞ theory. An H ∞-type performance criterion is formulated. The resulting control problem has several novel features distinguishing it from the standard smooth case already studied in the control literature: the presence of constraining dynamics on the boundary of the state space to ensure the physical property that queue lengths remain nonnegative, and jump discontinuities in any nonconstant state-feedback law caused by the finiteness of the admissible control set (choice of queue to be served). We arrive at the solution to the appropriate Hamilton–Jacobi equation via an analogue of the stable invariant manifold for the associated Hamiltonian flow (as was done by van der Schaft for the smooth case) and relate this solution to the (lower) value of a restricted differential game, similar to that formulated by Soravia for problems without constraining dynamics. An additional example is included which shows that the projection dynamics used to maintain nonnegativity of the state variables must be handled carefully in more general models involving interactions among the different queues. Primary motivation comes from the application to traffic signal control. Other application areas, such as manufacturing systems and computer networks, are mentioned.
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    Lasers in medical science 14 (1999), S. 20-23 
    ISSN: 1435-604X
    Keywords: Keywords: Diode laser; Expandable metal stent; Malignant dysphagia; Nd-YAG; Overgrowth; Tumour in-growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. Re-establishment of the oesophageal lumen is the main focus of care in patients with dysphagia due to re-blockage of in situ expandable metal stent (EMS). A total of 51 patients aged 44–89 years were intubated with EMS for dysphagia due to inoperable oesophagogastric carcinoma. Of these patients, 25 required follow-up endoscopy at variable intervals after stent insertion; 17 patients were found to have significant tumour in-growth (9), overgrowth (4) or both (4). All these patients were treated with Nd-YAG (70 W/s) or diode laser (30–50 W, continuous) for maintenance of satisfactory swallowing. The intensity of tumour ablation was similar with both types of lasers but four patients being treated with Nd-YAG laser developed deformity of EMS. This complication was not encountered with diode laser. The timing of the stent insertion should be carefully chosen since the longer the stent is in situ, the greater is the likelihood of tumour ingrowth or overgrowth. The combination of endoscopic laser therapy (ELT) and EMS may offer the best palliation, particularly when patient survival of several months is anticipated. ELT can effectively deal with tumour in-growth and overgrowth but care must be exercised in the use of Nd-YAG which can damage the structure of the EMS.
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    Lasers in medical science 14 (1999), S. 86-90 
    ISSN: 1435-604X
    Keywords: Keywords: Benign prostatic hyperplasia; Enucleation; Holmium; Laser; Prostatectomy; Resection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. At a wavelength of 2140 nm, the holmium:YAG (Ho:YAG) laser can be used for incision, ablation and resection of prostatic tissue. This laser has revolutionised the surgical management of benign prostatic hyperplasia (BPH) in our institution. Five different techniques have been utilised in evolving the current techniques using the Ho:YAG laser either alone or in combination with neodymium:YAG (Nd:YAG laser for the surgical management of BPH. The clinical outcome of 664 patients undergoing these procedures is presented. Enucleation of the prostatic adenoma using the holmium laser energy is the most common procedure presently performed at our institution for the surgical management of BPH. A mechanical tissue morcellator appears to be the most efficient way to remove prostatic tissue, once enucleated, from within the bladder.
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    Lasers in medical science 14 (1999), S. 129-135 
    ISSN: 1435-604X
    Keywords: Keywords: Microcirculation; Mono-l-aspartyl chlorin-e-6 (Npe-6); Photodynamic therapy (PDT); Vascular shut-down
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract. An experimental system that allows the white light observation of rapid changes in vessels without disturbance by red laser light was used. Mice were injected with mono-l-aspartyl chlorin-e-6 (Npe-6) i.v. via the tail vein and were immediately exposed to laser light. White emboli were observed forming on the inside of the vessel walls within seconds after commencement of light exposure. Emboli adhered to vessel walls and caused vascular obstruction. Light microscopy of the exposed material using fibrin staining was performed. Electron microscopy on the same material was also carried out. The embolisation time was influenced by both drug dose and laser power. With low laser power, it took a long time to stop the blood flow. Fibrin staining revealed the white emboli to be composed of fibrin. Electron microscopy findings revealed damage to endothelial cells and platelet aggregation. This study suggests that two main mechanisms (direct cellular damage and vascular shut-down ) might actually be complementary and synergistic in the production of vascular lesions using photodynamic therapy.
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    Lasers in medical science 14 (1999), S. 167-167 
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    Topics: Medicine , Physics , Technology
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    Lasers in medical science 14 (1999), S. 175-176 
    ISSN: 1435-604X
    Keywords: Keywords: Laser; Spider naevus
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    Topics: Medicine , Physics , Technology
    Notes: Abstract . A total of 112 spider naevi in 86 patients were treated with the tunable dye laser with a wavelength of 585 nm and pulse duration of 450 µs (SPTL 1, Candela Corporation, Wayland, MA). Complete ablation of the spider telangiectasia was achieved in 81 lesions (72.3%) partial ablation was achieved in 27 lesions (24.1%) and four (3.6%) lesions had no response to treatment. Transient hyperpigmentation was noted in one patient and minimal scarring in the form of a slight depression over the treated area was noted in another patient. The pulsed dye laser is shown to be effective in the treatment of spider naevi.
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  • 34
    ISSN: 1435-604X
    Keywords: Keywords: Carbon dioxide laser; Epulis fissuratum; Laser; Vestibuloplasty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . There have been numerous surgical techniques developed for removing the epulis fissuratum lesions in order to improve alveolar ridge contour and improving adaptation of full prostheses. Most of these techniques can cause postoperative complications, such as oedema, pain, difficulty in swallowing and jaw movements, haemorrhage, infections and slow placement of final prostheses. The use of carbon dioxide (CO2) laser for the surgical removal of epulis lesions has resulted in many significant improvements including convenient mucosa removal, no bleeding or need for sutures, and minimal postoperative pain and oedema. This study is of 15 cases of removal of extensive epulis with vestibuloplasty in the maxilla and mandible that was carried out with CO2 laser, with no postoperative complications, rapid healing, and excellent aesthetic and functional outcome, all of which allowed for more rapid placement of final prosthesis.
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  • 35
    ISSN: 1435-604X
    Keywords: Keywords: Feedback control; Indocyanine green dye; Laser-activated solid protein solder strips; Nerve repair; Temperature monitoring; Tensile strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . Laser-activated solid protein solder strips have been developed for peripheral nerve repair. Indocyanine green dye added to the solder strongly absorbs diode wavelengths (∼800 nm) and causes localised heating and coagulation of the albumin protein solder. The protein strengthens the tissue join, particularly during the acute healing phase postoperative, while shielding the underlying axons from excessive thermal damage. In this investigation of the solid protein solder technique for nerve repair, the effect of laser irradiance on weld strength and solder and tissue temperature were studied. The tensile strength of repaired nerves rose steadily with increased irradiance reaching a maximum of 105±10 N/cm2 at 12.7 W/cm2. At higher irradiances, tensile strength fell. The maximum temperature reached at the solder surface and at the solder/nerve interface, measured using a non-contact fibre optic radiometer and thermocouple, respectively, also rose steadily with laser irradiance. At 12.7 W/cm2, the temperatures reached at the surface and at the interface were 88±5°C and 71±4°C, respectively. This in vitro investigation demonstrates the feasibility of the laser-activated solid protein solder strips for peripheral nerve repair. The laser irradiance and the corresponding solder surface temperature for optimal tensile strength have been identified.
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  • 36
    ISSN: 1435-604X
    Keywords: Keywords: Adenocarcinoma; Aminolaevulinic acid; Barrett's oesophagus; Dysplasia; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . Photodynamic therapy (PDT) may have a role in the prevention of oesophageal cancer. Ten patients with Barrett's oesophagus, three with low-grade dysplasia (LGD), four with high-grade dysplasia (HGD), one with carcinoma in situ and two with invasive carcinoma, were treated with PDT. All received 30 mg/kg aminolaevulinic acid (ALA) followed 4 h later by laser endoscopy. Half were treated with red light (630 nm; 100 mW/cm2 for 1000 s) and half with green light (514 nm; 100 mW/cm2 for 500 s). Columnar epithelial regression was seen in all patients with dysplasia (mean area decrease 44%; range 10–100%), with apparent elimination of dysplasia in all cases. In patients with in situ or invasive carcinoma, no response was seen. ALA-induced PDT, using either red or green light, produces effective ablation of dysplastic Barrett's oesophagus, hence may have a role in the prevention of oesophageal carcinoma, but has little effect on in situ or invasive adenocarcinoma.
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    Research in engineering design 11 (1999), S. 55-66 
    ISSN: 1435-6066
    Keywords: Key words:Advancing front techniques – CAD/CAM – Mesh generation – Nodal density – Remeshing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: This paper presents a method to integrate in a better way the finite element method in the CAD/CAM process for two-dimensional problems, through efficient and automatic meshing and remeshing procedures. During the design step, the lack of integration between geometric modeling and numerical analysis remains a crucial problem and it still tends to restrain the use of finite element methods to a small number of engineers. Here we tackle the problem of the automatic remeshing of an object in the context of minor changes in its geometry and topology without restarting the mesh generation from the beginning. We have developed a mesh generator that is able to adapt a previous mesh, through two complementary strategies (for 2D cases) to a new geometry without destroying the whole initial discretization. We also present the possible extension of these concepts to three-dimensional problems.
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    Research in engineering design 11 (1999), S. 229-253 
    ISSN: 1435-6066
    Keywords: Key words:Assembly – Assembly sequence analysis – Feature-based design of assemblies – Kinematic assembly – Kinematic constraint – Screw theory – Tolerance analysis of assemblies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract. This paper presents a theory to support the design of assemblies. It brings together prior work in a new synthesis, resulting in a top-down process for designing assemblies so that they deliver geometric Key Characteristics (KCs) that achieve top level customer requirements. The theory applies to assemblies that take the form of mechanisms (e.g. engines) or structures (e.g. aircraft fuselages), but has less relevance to assemblies that take the form of connective or distributive systems (e.g. hydraulic piping). The theory shows how kinematically constrained (statically determinate) assemblies can be unambiguously designed to satisfy geometrically-defined customer requirements. The top-down process presented here begins by creating a kinematic constraint structure and a systematic scheme by which parts are located in space relative to each other, followed by declaration of assembly features that join parts in such a way as to create the desired constraint relationships. This process captures design intent by creating a connective data model that contains information to support relevant analyses such as variation buildup, constraint analysis, and establishment of constraint-consistent assembly sequences. Adjustable assemblies, assemblies built using fixtures, and selective assemblies can also be described by this theory. Problems arising from multiple KCs and KC conflict can be identified. Issues unresolved by the theory are also noted.
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    Research in engineering design 11 (1999), S. 103-115 
    ISSN: 1435-6066
    Keywords: Key words:Design – QFD – Requirements – Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract: We have developed a taxonomy that classifies those needs of a corporation that impact product design. We call these needs corporate requirements. In contrast to the consumer or end-user requirements, corporate requirements come from internal sources such as marketing, finance, manufacturing, and service. This taxonomy allows for an organized method of gathering, managing, and retrieving the requirements. The taxonomy also helps to facilitate a broader, clearer form of Quality Function Deployment. Generic in nature, this taxonomy provides a template with which to create taxonomies for a given product within a given company or industry. We include an industrial case study to demonstrate this concept.
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    Biomedical microdevices 2 (1999), S. 91-92 
    ISSN: 1572-8781
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  • 41
    ISSN: 1572-8781
    Keywords: tumor pathology semiconductor microfabrication microfluidics nanolasers ; nanotechnology cytometry
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    Topics: Medicine , Technology
    Notes: Abstract Through recent interdisciplinary scientific research, modern medicine has significantly advanced the diagnosis and treatment of disease. However, little progress has been made in reducing the death rate due to cancer, which remains the leading cause of death in much of the world. Pathologists routinely rely on microscopic examination of cell morphology using methods that originated over a hundred years ago. These staining methods are labor-intensive, time-consuming, and frequently in error. New micro-analytical methods1 (JBM, 1998; Harrison et al., 1993; Ramsey et al., 1995; Mauro Ferrari, Lynn Jelinski, 1994; Anderson et al., 1996; Carlson et al., 1996) for high speed (real time) automated screening of tissues and cells are critical to advancing pathology and hold the potential for improving diagnosis and treatment of cancer patients. By teaming experts in semiconductor physics, microfabrication, surface chemistry, film synthesis, and fluid mechanics with microbiologists and medical doctors, we are investigating nanostructured biochips to assess the condition of tumor cells by quantifying total protein content. This technique has the potential to quickly identify a cell population that has begun rapid protein synthesis and mitosis, characteristic of tumor cell proliferation. By incorporating microfluidic flow of cells inside the laser microcavity for the first time, we have enabled high throughput screening of cells in their native state, without need of chemical staining, in a sensitive nanodevice.
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    Biomedical microdevices 1 (1999), S. 97-98 
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    Biomedical microdevices 1 (1999), S. 107-112 
    ISSN: 1572-8781
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    Notes: Abstract The use of microfabricated DNA analysis tools utilizing microfluidics will provide the next generation of inexpensive DNA diagnostics. It will also provide methodologies to measure gene expression in a massively parallel manner, eventually providing the methodologies to measure most or all the human genes of significance on a single chip. These technologies, including PCR analysis, electrophoresis and gene chips are described using examples from the archival literature.
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    Biomedical microdevices 1 (1999), S. 139-153 
    ISSN: 1572-8781
    Keywords: array biosensor ; automation ; CCD imaging ; fluorescence imaging ; antibody patterning ; waveguide
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    Notes: Abstract Optical and fluidics systems have been developed as central components for an automated array biosensor. Disposable planar waveguides are patterned with immobilized capture antibodies using a physically isolated patterning (PIP) method. The PIP method enables simultaneous deposition of several antibodies and completely circumvents cross-immobilization problems encountered with other array deposition processes. A multi-channel fluidics cell allows numerous assays to be performed on the patterned waveguide. The sensing arrays are optically interrogated using a diode laser with a tailored output to optimize coupling to and maximize excitation uniformity within the waveguide. A patterned cladding is employed to optically isolate the waveguide from perturbations induced by the permanently attached flow cells. Compact optics image the evanescently excited fluorescence onto a large area, cooled CCD array. The image data is processed and automated signal analysis corrects for local background and noise variations.
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  • 45
    ISSN: 1572-8781
    Keywords: drug discovery ; CellChip ; high content screening ; fluorescence ; patterning ; sensors ; microarrays ; bioinformatics ; tissue engineering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A major bottleneck to the early stages of drug discovery is the absence of integration of high throughput screening (HTS) with smarter assays that screen “hits” from HTS to identify leads (High content screening, HCS). We propose a solution using novel fluorescent engineered protein biosensors integrated into a miniaturized live-cell-based screening platform (CellChip™ System) that markedly shortens the early drug discovery process. Microarrays of selectively localized living cells, containing engineered fluorescent biosensors, serve to integrate HTS and HCS onto a single platform. HTS “hits” are identified using one biosensor while reading the whole chip array of cells. The high-biological content information is then obtained from probing target activity at inter-cellular, sub-cellular and molecular levels in the “hit” wells. HCS assays yield temporal-spatial dynamic maps of the drug-target interaction within each living cell. We predict that a new platform incorporating HTS and HCS assays that are automated, miniaturized, and information-rich will dramatically improve the decision making process in the pharmaceutical industry and optimize lead compounds during the early part of the drug discovery process. There is an opportunity to establish a new paradigm for drug discovery based on integration of fluorescence technology, micropatterning of living cells, automated optical detection and data analysis, and a new generation of knowledge building bioinformatics approaches. The technology will have an expansive impact spanning the fields of drug discovery, biomedical research, environmental monitoring, life sciences, and clinical diagnostics. The integrated CellChip™ Platform with miniaturized tissue-specific microarrayed cells capable of providing inter-cellular and sub-cellular spatio-temporal information in response to drug-cell, toxin-cell, or pathogen-cell interactions will serve to enhance the decision making process in drug discovery, toxicology, and clinical diagnostics.
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    Biomedical microdevices 2 (1999), S. 145-150 
    ISSN: 1572-8781
    Keywords: electroporation ; micro-electroporation chip ; cell membrane electrical currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Electroporation is commonly used in biotechnology to introduce macromolecules into cells. We have developed a micro-electroporation chip that incorporates a live biological cell in the electrical circuit. The chip configuration forces electrical currents to pass through the cell, thereby producing electrically measurable information about the electroporation state of the cell. The cell membrane electrical properties make the cell function as a diode in the electroporation current-voltage range. The chip is transparent in the area of the cell to allow microscope viewing. during electroporation. This chip may be used to study the fundamental biophysics of cell electroporation and in biotechnology for controlled macromolecule introduction in individual cells. We describe the chip principle and show results on the electrical current-voltage pattern during reversible and irreversible electroporation in individual cells.
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  • 47
    ISSN: 1572-8781
    Keywords: MPC ; BMA ; AMPS ; biocompatibility ; cellulose triacetate ; diffusion-limiting effect ; glucose sensor ; needle type ; glucose oxidase ; serum ; whole blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A multifunctional membrane with biocompatibility, diffusion-limiting effect, and the ability to curtail the responses of an H2O2 electrode to ascorbate and urate was prepared. It was composed of MB, AB, and CTA, where MB is the copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butylmethacrylate (BMA), AB is the copolymer of acrylamide-2-methylpropane sulfonic acid (AMPS) and BMA, CTA is cellulose triacetate. Investigation of the biocompatibility of this membrane showed that, compared with CTA, relatively few platelets bound to it. The membrane was coated onto the working electrode of a needle-type glucose sensor on which immobilized glucose oxidase membrane has been coated. The sensor did not respond to ascorbate and urate at their concentration normally encountered in blood. Its response was not inhibited by metal ions in blood at usual concentration. The sensor exhibited superior thermostability in addition to a rapid response (〈90 seconds in batch operation), good reproducibility (RE〈5%), good stability (more than 36 hours continuously in heparinized whole blood), and a wide dynamic range (5–650 mg/dl glucose). The sensor was used to determine glucose in serum. The data obtained from the sensor showed good agreement with that from a clinical autoanalyzer (R=0.973).
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    Biomedical microdevices 2 (1999), S. 87-88 
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  • 49
    ISSN: 1572-8781
    Keywords: nondestructive testing ; evanescent microwave imaging ; quantitative testing ; conductivity in biomaterials ; high resolution imaging ; material non-uniformity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Scanning tunneling and atomic force microscopes (STM and AFM) are used to study biological materials. These methods, often capable of achieving atomic resolutions, reveal fascinating information regarding the inner workings of these materials. However, both STM and AFM require physical contact to the specimen. In the case of STM, the specimen needs to be conducting as well. Here we introduce a new method for imaging biological materials through air or a suitable liquid using decaying or evanescent fields at the tip of a properly designed microwave resonator. This novel method involves the use of an evanescent microwave probe (EMP) and is capable of imaging a variety of non-uniformities in biological materials including conductivity, permittivity, and density variations. EMP is a non-contact and non-destructive sensor and it does not require conducting specimens. Its spatial resolution is currently around 0.4 μm at 1 GHz. We have used this probe to map non-uniformities in a variety of materials including metals, semiconductors, insulators, and biological and botanical samples. Here we discuss applications of EMP imaging in bone, teeth, botanical, and agricultural specimens.
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    Biomedical microdevices 1 (1999), S. 121-130 
    ISSN: 1572-8781
    Keywords: electrochemical actuation ; micropump ; liquid dosing ; gas bubbles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract In this paper a micromachined electrochemically driven pump capable of dosing precise nanoliter amounts of liquid is presented. The pump consists of a micromachined channel structure realized in silicon by reactive ion etching. On top of this structure a Pyrex® cover piece with noble metal electrodes was bonded. The fluid to be dispensed is stored in a meander shaped reservoir which is part of the channel structure. This meander starts in an electrolyte solution containing reservoir, on top of which two noble metal electrodes are positioned. By the electrochemical production of gas bubbles by electrolysis of water at these electrodes, liquid can be driven out of the meander. The measured volume displacements were in close agreement with theory. Pump rates as low as a few nl/s could accurately be controlled via the actuation current through the electrodes. By applying current pulses rather than a continuous current, preset amounts of fluid in the nanoliter range could be dosed successfully. Because the resulting device consists of simple channel structures and metal electrodes it can easily be integrated in miniaturized chemical analysis systems to dose reagents or calibration solutions.
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    Biomedical microdevices 2 (1999), S. 9-10 
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  • 52
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    Biomedical microdevices 2 (1999), S. 51-60 
    ISSN: 1572-8781
    Keywords: magnetoelastic ; remote query ; microdevice ; sensor ; glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Magnetoelastic thin-film sensors can be considered the magnetic analog of an acoustic bell: in response to an externally applied magnetic field impulse the sensors ring like a bell, emitting magnetic flux with a characteristic resonant frequency. The magnetic flux can be detected remotely, external to the test area, using a pick-up coil. By monitoring changes in the characteristic resonant frequency of the sensor multiple environmental parameters can be measured. In this work we report on application of magnetoelastic sensors for remote query measurement of temperature, pressure, viscosity and, in combination with a glucose-responding mass-changing polymer, in situ measurement of biological-level glucose concentrations. The advantage of using magnetoelastic sensors is that they are monitored remotely, without the need for direct physical connections such as wires or cables, nor line-of-sight alignment as needed with optical detection methods. The remote query capability allows the magnetoelastic sensors to be monitored from inside sealed, opaque containers. Depending upon the application magnetoelastic sensors can be sized from micrometer to millimeter dimensional scales, and have a material cost of approximately $0.001 allowing for their use on a disposable basis.
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  • 53
    ISSN: 1572-8781
    Keywords: cell sorting ; travelling wave dielectrophoresis ; filed-flow-fractionation ; computer microvision
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    Topics: Medicine , Technology
    Notes: Abstract We describe a microfluidic device for separating cells according to their dielectric properties by combining 2-dimensional dielectrophoretic forces with field-flow-fractionation. The device comprises a thin chamber in which a travelling-wave electrical field is generated by a planar, multilayer microelectrode array at the bottom. Under the balance of gravitational and dielectrophoretic levitation forces, cells introduced into the device are positioned at different equilibrium heights in a velocity profile established inside the chamber, and thereby transported at different velocities by the fluid. Simultaneously, cells are subjected to a horizontal travelling-wave dielectrophoretic force that deflects them across the flow stream. The 2-dimensional dielectrophoretic forces acting on cells and the associated velocities in the fluid-flow and travelling-field directions depend sensitively on cell dielectric properties. The responses of cultured MDA-435 human breast cancer, HL-60 human leukemia and DS19 murine erythroleukemia cells, and of peripheral blood mononuclear (PBMN) cells were studied as functions of the frequency and voltage of the applied electric signals, and of the fluid flow rate. Significant differences were observed between the responses of different cell types. Cell separation was demonstrated by the differential redistribution of MDA-435 and PBMN cells as they flowed through the device. The device can be readily integrated with other microfluidic components for microscale sample preparation and analysis.
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  • 54
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    Biomedical microdevices 1 (1999), S. 113-119 
    ISSN: 1572-8781
    Keywords: bioseparation ; filter ; MEMS ; micromachining ; BioMEMS
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    Topics: Medicine , Technology
    Notes: Abstract For successful size separation in biomedical applications, the filter used must meet several strict criteria. Not only must it have precisely-machined sub-100 nm pores (〈5% variation), but it must also be able to handle large and small volumes with very high reduction ratios (〉104). In this paper, we will present a bulk-micromachined, direct-bonded silicon nanofilter that can remove particles as small as 44 nm. In doing so, we will describe the fabrication, the gas and liquid characterization, and the filtrations studies done on 44 nm and 100 nm beads.
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  • 55
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    Biomedical microdevices 2 (1999), S. 5-7 
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  • 56
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    Keywords: BioMEMS ; nanotechnology ; microfabrication ; membranes ; silicon
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    Notes: Abstract The ability to create well-defined and controlled interfaces has been an area of great interest over the last few years, particularly in the biomedical arena. This paper will describe the development of technology for the fabrication of nanopore membranes, and their operation in biological environments. With monodisperse pores sizes as small as 10 nanometers, these membranes offer advantages in their reproducibility, and their ability to be integrated with controlled biochemical surface modification protocols. A comprehensive review of results in the areas of nanopore and biocapsule microfabrication technologies, biocompatibility of nanomembrane materials, biologically appropriate post-processing protocols (bonding, sterilization), surface modification protocols, and appropriate mass transport models will be presented. The results point to the potential of using such technologies for therapeutic applications including immunoisolation biocapsules, drug delivery devices, and targeted biorecognition platforms.
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  • 57
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    Biomedical microdevices 2 (1999), S. 61-72 
    ISSN: 1572-8781
    Keywords: biohybrid cell culture ; chick ; neurite growth ; immunocytochemistry ; microphotodiode ; optoelectric stimulation ; retinal implant ; retinitis pigmentosa ; scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Various neurodegenerative diseases of the retina lead to blindness. Since no pharmacological or gene therapy is available, the alternative concept of neuroprostheses has stimulated the development of micromachined photovoltaic devices. One strategy aims to replace degenerated photoreceptors by microphotodiode arrays (MPDA). MPDAs in the subretinal space shall transform light stimuli into electrical current for the stimulation of still unhampered retinal neurons. MPDAs were fabricated as silicon based multilayered PIN microstructures comprising titanium nitride stimulation electrodes of an area of 8 × 8 μm2. In an effort to develop meaningful tools to evaluate functional MPDA biocompatibility, a novel in vitro system was designed. Retinal cells were cultured on MPDAs, while current generation in MPDAs as in the eye was imitated by light emitting diodes (LED) operating at different wavelengths. For analysis epifluorescence and scannning electron microscopy was employed. MPDAs displayed increasing current delivery with increasing illumination. Surface modification of MPDAs including oxygen plasma treatment and adsorption of polyanions together with laminin were found to render the MPDA surface permissive for cell adhesion. Cell vitality tests using fluorescence markers revealed no adverse effects of optoelectric stimulation via LED/MPDAs. In addition, neurite formation and the expression of differentiation antigen 2A10 were unaffected after stimulation. Optoelectric stimulation allowed regular differentiation of various retinal cell types. In summary, the data provide the first evidence that optoelectric stimulation via MPDAs does not hamper cellular integrity under the experimental conditions chosen. The results support the concept of microphotodiodes as a retinal prosthesis.
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  • 58
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    Biomedical microdevices 2 (1999), S. 89-90 
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    Biomedical microdevices 2 (1999), S. 151-157 
    ISSN: 1572-8781
    Keywords: tensile test ; collagen fiber ; mechanical property ; patellar tendon ; biomechanics
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    Topics: Medicine , Technology
    Notes: Abstract Tensile properties of collagen fibers of approximately 1 μm in diameter were determined using a newly developed micro tensile test system for cells and fine fibrous biological tissues. The test system consists of a thermostatic test chamber, an inverted microscope, micromanipulators, a direct drive linear actuator, a cantilever-type load cell, and a video dimension analyzer (VDA). The fibers were isolated with a mechanical method from collagen fascicles (approximately 300 μm in diameter) cut out from the rabbit patellar tendon. The ends of each fiber were attached to the tips of a pair of glass microtubes (15 to 20 μm in outer diameter) using a cyanoacrylate adhesive. One of the microtubes was attached to the load cell; the other one was connected to the linear actuator which was utilized to stretch the fiber. Load applied to the fiber was measured with the load cell, while its elongation was determined with the VDA using the images of the edges of the adhesive as markers. Tangent modulus, tensile strength, and strain at failure of the tested fibers were 54.3± 25.1 MPa, 8.5± 2.6 MPa, and 21.6± 3.0%, respectively. These values were much different from those of collagen fascicles (300 μm in diameter) cut out from the rabbit patellar tendon and also from those of the bulk patellar tendon (Trans. ASME, J. Biomech. Eng. 121, 124–294, 1999); for example, tensile strength and strain at failure of the fibers were approximately 50 and 200% of those of the fascicles, respectively. These results suggest that the mechanical interactions between fibers and between fibers and ground substances contribute much to the mechanical properties of collagen fascicles and bulk tendons.
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    Biomedical microdevices 1 (1999), S. 99-106 
    ISSN: 1572-8781
    Keywords: patents ; inventions ; claim scope ; microfabrication
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    Topics: Medicine , Technology
    Notes: Abstract Inventors who are mystified by the concepts of “nonobviousness” and “enablement” may be surprised to find that the two concepts have a simple explanation in information theory. Viewing an invention as a low-probability, high-information event helps explain why an invention that appears inventive (nonobvious) to an inventor may appear obvious to a patent examiner, and suggests some strategies for overcoming the examiner's bias. Viewing enablement as a means of increasing the probability that a claimed invention can be practiced successfully helps in understanding how to support a broad claim effectively by virtual or “paper” patenting. The notion of entropy, or mean information content, as applied to inventions, may guide inventors in their search for new inventions.
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  • 61
    ISSN: 1572-8781
    Keywords: BioMEMS ; microfabricated biocapsule; immunoisolation ; insulinoma
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    Notes: Abstract This study examines the viability and functionality of two insulinoma cell lines, RIN (1048) and βTC6F7, encapsulated within microfabricated biocapsules. Surface and bulk micromachining are integrated in the biocapsule fabrication process, resulting in a diffusion membrane with uniform pore size distribution as well as mechanical and chemical stability, surrounded by an anisotropically-etched silicon wafer, which serves as the encapsulation cavity. Insulinoma cells (4500 cells/biocapsule) were enclosed within these microfabricated biocapsules and subjected to a static incubation study after either implantation in BALB-C mice or incubation in vitro. Examination of retrieved microfabricated biocapsules revealed an insulin stimulatory index of approximately 1.5 for encapsulated RIN cells and 3.6 for encapsulated βTC6F7 cells for biocapsules with 18 nm pore sized microfabricated membranes, similar to indices of biocapsules incubated in vitro. There was an 80% decrease in cell stimulatory response between in vitro and in vivo 66 nm-biocapsules as compared to 20% for 18 nm-biocapsules, indicating that the immunoisolatory effectiveness depends greatly on achieving uniform pore sizes in the size range of 18 nm or smaller. The present study demonstrates the feasibility of using microfabricated biocapsules for the immunoisolation of insulinoma cells lines. The microfabricated biocapsule may serve as an alternative to conventional polymeric based biocapsules for possible use as in vivo insulin secreting bioreactor.
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  • 62
    ISSN: 1572-8781
    Keywords: bioMEMS ; microtexture ; cardiac myocyte ; cellular adhesion
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    Notes: Abstract In order to understand the role of tissue adaptation to altered physiological states, a more physiologically and dimensionally relevant in vitro model of cardiac myocyte organization has been developed. This new cell culture system, created by microfabrication technology, provides an environment in which cells can maintain a differentiated in vivo cell phenotype. By creating microtextured geometries of varied dimension, we are able to maximize the perpendicular surface area for myocyte attachment. These platforms provide a biocompatible surface with specific microarchitectures upon which cells exhibit enhanced cellular adhesion due to increased surface area, three-dimensional geometries, and bioacceptable attachment moieties. These microtextured membranes are created using photolithography and microfabrication techniques. Silicone and polyglycolic/lactic acid interfaces with specified microarchitecture and surface chemistry have been designed, microfabricated, and characterized for this purpose. Advantages of the microtextured membranes include the high degree of reproducibility and the ability to create features on the micron and submicron size scale. Because of the flexibility of substrate material and the ease of creating micron size structures, this technique can be applied to many other physiological and biological systems, particularly for cell physiology and mechanobiology studies.
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  • 63
    ISSN: 1572-8781
    Keywords: whole cell biosensor ; physiometer ; thermopile ; sensor array ; micromachining ; high-throughput drug screening ; cell metabolism ; functional assay ; microtiterplate
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    Topics: Medicine , Technology
    Notes: Abstract We report on a micromachined silicon chip that is capable of providing a high-throughput functional assay based on calorimetry. A prototype twin microcalorimeter based on the Seebeck effect has been fabricated by using IC technology process steps in combination with micromachined postprocessing techniques. A biocompatible liquid rubber membrane supports two identical 0.5×2 cm2 measurement chambers, situated at the cold and hot junction sites of a thermopile. The thermopile consists of 666 aluminum/p+-polysilicon thermocouples. The chambers can house up to 106 eukaryotic cells cultured to confluence. The advantage of the device over microcalorimeters on the market, is the integration of the measurement channels on chip, rendering microvolume reaction vessels, ranging from 10 to 600 µl, in the closest possible contact with the thermopile sensor (no springs are needed). Power and temperature sensitivity of the sensor are 23 V/W and 130 mV/K, respectively. The small thermal inertia of the microchannels results in the short response time of 70 s, when filled with 50% of water. Biological experiments were done with cultured kidney cells of Xenopus laevis (A6). The thermal equilibration time of the device is 45 minutes. Stimulation of transport mechanisms by reducing bath osmolality by 50% increased metabolism by 20%. Our results show that it is feasible to apply this large-area, small-volume whole-cell biosensor for drug discovery, where the binding assays that are commonly used to provide high-throughput need to be complemented with a functional assay. Solutions are brought onto the sensor by a simple pipette, making the use of an industrial microtiterplate dispenser feasible on a nx96-array of the microcalorimeter biosensor. Such an array of biosensors has been designed based on a new set of requirements as set forth by people in the field.
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    Biomedical microdevices 2 (1999), S. 131-144 
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    Notes: Abstract The possibility to replace damaged or diseased organs with artificial tissues engineered from a combination of living cells and biocompatible scaffolds is becoming a reality through multi-disciplinary efforts. A number of critical components within this effort are being facilitated by microfabrication and MEMS approaches, including research tools to elucidate mechanisms which control cellular behavior as well as development of methods to manufacture cellular scaffolds at ever higher resolutions. This article reviews recent advances in tissue engineering that have been facilitated by interaction with the microfabrication community. We highlight the potential opportunities for microfabrication to make to the development of mainstream medical therapies for tissue replacement.
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    Journal of marine science and technology 4 (1999), S. 16-26 
    ISSN: 1437-8213
    Keywords: Key words: capsizing ; broaching ; surf-riding ; heteroclinic bifurcation ; following seas ; quartering seas
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    Topics: Geosciences , Technology
    Notes: Abstract: To provide a theoretical methodology to predict the critical condition for capsizing due to broaching, a nonlinear dynamical system approach was applied to the surge–sway–yaw–roll motion of a ship running with an autopilot in following and quartering seas. Fixed points of a mathematical model for the ship motion and unstable manifolds of the fixed point near the wave crest were systematically investigated. As a result, the existence of heteroclinic bifurcation was identified. With numerical experiments, it was confirmed that this heteroclinic bifurcation reasonably well represents the critical condition for capsizing due to broaching. Thus the nonlinear dynamical approach can be substituted for tedious numerical experiments.
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    Journal of marine science and technology 4 (1999), S. 27-34 
    ISSN: 1437-8213
    Keywords: Key words: sloshing ; higher-order BEM ; thin plate theory ; hydroelasticity ; radiation pressure
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    Topics: Geosciences , Technology
    Notes: Abstract: The sloshing problem in cargo tanks is studied through experiments and numerical analysis. The fluid motion is described using a higher-order boundary element method and the structural response by a thin plate theory. It was found that hydraulic jumps are formed when the excitation frequency is close to the resonance frequency in the case of low filling depth. In the case of high filling depth, the flow resonates and hits the top of the tank, thus inducing a large impact pressure. The pressure on the flexible plate shows amplified initial peaks followed by oscillatory components, the frequency of which coincides with the natural frequencies of the plate in water as a result of hydroelastic effects.
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    Journal of marine science and technology 4 (1999), S. 45-57 
    ISSN: 1437-8213
    Keywords: Key words: capsizing ; broaching ; stability loss ; bow diving following seas ; quartering seas
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    Topics: Geosciences , Technology
    Notes: Abstract: A systematic method for assessing intact ship stability with a free-running model in a seakeeping and maneuvering basin is proposed in this paper. Model experiments were carried out in extremely steep regular waves for a model drifting, running in head seas, and quartering seas. This method was applied to two purse seiners, and efficiently identified thresholds in metacentric heights for capsizing of these ships. These capsizing thresholds are compared with requirements of the IMO Code on Intact Stability. This series of model experiments also confirms that capsizing at the threshold occurs only in quartering seas, and shows that capsizing is caused by broaching, loss of stability on a wave crest, or bow diving.
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    Journal of marine science and technology 4 (1999), S. 35-43 
    ISSN: 1437-8213
    Keywords: Key words: product model ; Petri nets ; scheduling ; CIM
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    Notes: Abstract: There are many restrictions on production in the factory. The most efficient production schedule should be planned taking these restrictions into account. Professional skill is necessary to plan the best schedule. A schedule planner has to deal with so much information during production planning that it is difficult to plan the best production schedule with a consideration of so many restrictions. In this study we introduced the use of Petri nets to support such production planning with a computer. Petri nets have been widely used to simulate production because of their capability of modeling concurrency, synchronization, and sequencing in discrete-event systems. This paper reports on implementing a simulation system for the shipyard. We had already implemented a production planning support system for a shipyard that is a part of the computer integrated manufacturing (CIM) system in shipbuilding. Based on this system, we implemented a shipyard simulator that can simulate the production activity in the shipyard. We therefore have defined a shipyard model. The production conditions can be changed, and the efficiency of a schedule can be evaluated. This paper discusses the effectiveness of using a factory simulator.
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    Journal of marine science and technology 4 (1999), S. 163-172 
    ISSN: 1437-8213
    Keywords: Key words: sail ; CFD ; design by simulation
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    Topics: Geosciences , Technology
    Notes: Abstract: A finite-volume method was applied to a simulation of the flow about the sail system of IACC sailing boats. The interface boundary technique was employed to generate a proper grid system for the two-sails system, which is composed of head and main sails. The turbulence model was carefully chosen by numerical test, and the most reliable simulation method was completed and used to design the sails. The suitability of the method is demonstrated by some examples of design applications.
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    Journal of marine science and technology 4 (1999), S. 187-199 
    ISSN: 1437-8213
    Keywords: Key words: learning tracking controller ; flexible structural control ; unknown disturbances ; precise mating ; automated offshore installation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: During the installation operations of underwater structures, offshore structures such as semisubmersibles, the steady nonlinear hydrodynamic force due to the ocean current, the tidal current, and the hydrodynamic interaction between structures are regarded as major disturbances. Generally, it is difficult and very expensive to collect information about these disturbances in advance, although such knowledge would be important and necessary for precise installation. Because of this situation, we have proposed a learning tracking controller (LTC) for automated tracking/docking operations of offshore structures. The LTC can be operated without any information about current, and can be applied to the installation problem of flexible structures whose flexibility cannot be ignored. In order to confirm the effectiveness of the LTC, basin tests were carried out using experimental models with an unknown current. Two types of basin experiment were executed using an ultrasound ranging system and thrusters. One was trajectory tracking of a semisubmersible, and the other was the precise mating of flexible underwater structures. In both cases the LTC showed good performance, and in the latter case in particular, two flexible models were successfully made to track the given trajectory and dock to the docking targets with an accuracy of ±5 mm, after the trajectory had been tracked six to seven times for learning purposes. No elastic responses were excited in the flexible model.
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    Journal of marine science and technology 4 (1999), S. 58-67 
    ISSN: 1437-8213
    Keywords: Key words: marine risers ; impact ; collision ; energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: One of the main challenges in estimating impact energy in collisions between marine risers is the assessment of the riser mass involved in the collision. Evidently the entire riser mass does not contribute to the collision. Hence, the question is: What is the equivalent riser mass which contributes to the impact energy? This article presents three different ways of estimating the riser mass participating in the collision energy. The first method is strictly experimental. The second method uses a numerical experiment together with system identification techniques. The third method is a strictly analytical method, which results in an asymptotically upper bounded estimate of the participating mass. Two risers are examined as case studies. The first riser is a 1 : 100 model scale riser used in collision experiments carried out at Marintek's towing tank in Trondheim, Norway. The second case uses a real world riser in use on the Troll B oil production platform operating in the North Sea. The proposed methods yield consistent and comparable results.
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    Journal of marine science and technology 4 (1999), S. 68-75 
    ISSN: 1437-8213
    Keywords: Key words: mooring line tension ; observer ; maximum entropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: A method for measuring mooring line tension is proposed based on observation of the natural frequencies of the mooring line segment between the winch and the fairlead. The anchor line tension is observed through the string equation where an analytical expression for the line's eigen-frequencies is obtained. The tension is observed on line by utilizing a nonparametric system identification approach in which the peaks of a maximum entropy spectrum of the transverse acceleration measures of the vibrating string are automatically identified. The method is verified against full-scale data from the Troll B floating concrete oil production platform operating in the North Sea.
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    Journal of marine science and technology 4 (1999), S. 93-93 
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    Journal of marine science and technology 4 (1999), S. 76-83 
    ISSN: 1437-8213
    Keywords: Key words: VLFS (very large floating structures) ; hydroelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: This paper deals with the dispersion relation of hydroelastic waves in pontoon-type very large floating structures (VLFS) using a simple beam modeling, where the term hydroelastic waves means propagation of deflection vibrations in VLFS. The purpose of this paper is to show the properties of the hydroelastic waves. The dispersion relation of hydroelastic waves propagating in an infinite plate floating on the water is derived based on the linear water wave theory. The effects of the water depth and of the bending rigidity of the floating plate on the wavelength, phase velocity, and group velocity of the hydroelastic waves are shown theoretically or numerically. Then, the dispersion relation of hydroelastic waves in a finite plate floating on shallow water is investigated. It is shown that the wavelength or the phase velocity of the hydroelastic waves varies with the location in the plate.
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  • 75
    ISSN: 1437-8213
    Keywords: Key words:Nakhodka oil spill, oil spill numerical simulation, Japan Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: A simulation of the movement of spilled oil after the incident of the Russian tanker Nakhodka in the Sea of Japan, in January 1997, was performed by a particle tracking model incorporating advection by currents, random diffusion, the buoyancy effect, the parameterization of oil evaporation, biodegradation, and beaching. The currents advecting spilled oil were defined by surface wind drift superposed on the three-dimensional ocean currents obtained by the Geophysical Fluid Dynamics Laboratory modular ocean model (GFDL MOM), which was forced by the climatological monthly mean meteorological data, or by the European Center for Medium Range Weather Forecasts (ECMWF) daily meteorological data, and assimilated sea surface topography detected by satellite altimeter. A number of experiments with different parameters and situations showed that the wide geographical spread of oil observed is not explained by wind drift alone, and that including the simulated climatological currents gives better results. The combination of surface wind drift and daily ocean currents shows the best agreement between the model and observations except in some coastal areas. The daily meteorological effect on the ocean circulation model results in a stronger variability of currents that closely simulates some features of the nonlinear large-scale horizontal turbulent diffusion of oil. The effect of different parameterizations for the size distribution of model oil particles is discussed.
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    Journal of marine science and technology 4 (1999), S. 117-122 
    ISSN: 1437-8213
    Keywords: Key words: anti-pitching fin, ship control, seakeeping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: We have investigated the usefulness of active stabilizing fins to reduce ship pitching under varying forward speeds, and in varying wave lengths. A 4-m self-propelled model ship and an electrohydraulically driven stabilizing fin system were used in our experiment. Pitch angles, pitch rates, and ship forward speeds were measured and fed back to a controller to calculate the deflection angle of the stabilizing fin. The effects of fin nonlinearity on achievable pitch reduction performance are discussed. It is shown that the desired pitch response can only be achieved when the fin is operated in the linear region. The overall dynamic response of the ship approaches open-loop behavior when the degree of nonlinearity is high. This simple analysis of the pitch stablizing system provides basic information to ship designers. Experimental results validate these design guidelines.
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    Journal of marine science and technology 4 (1999), S. 123-153 
    ISSN: 1437-8213
    Keywords: Key words: very large floating structure, VLFS, hydroelastic response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: New numerical methods are presented for hydroelastic analyses of a very large floating structure (VLFS) of several kilometers length and width. Several methods are presented that accelerate computation without an appreciable loss of accuracy. The accuracy and efficiency of the proposed methods are validated through comparisons with other numerical results as well as with existing experimental results. After confirming the effectiveness of the methods presented, various characteristics of the hydroelastic behavior of VLFSs are examined, using the proposed methods as numerical tools.
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    Journal of marine science and technology 4 (1999), S. 180-186 
    ISSN: 1437-8213
    Keywords: Key words: variational principle ; unknown boundary problem ; planing ship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: A variational principle is presented to solve the problem of determining the unknown wetted surface of a planing ship on still water under gravity. The functional associated with the variational principle is expressed by the unknown wetted length distribution, the vortex line function, and the circulation distribution around the longitudinal sections, not by the bottom pressure distribution. In addition, the variational principle is adjoined with pseudoflow, here called reverse flow. The extremal of the functional satisfy the hull boundary integral equation in a similar way to that of lifting-surface theory and the elevated water surface condition along the spray root line. Both are sufficient to determine the wetted surface. A method of high aspect ratio approximation is also investigated. A simple relation is obtained between the wetted surface when moving and at standstill. The calculated shapes of the wetted surface of a planing plate agreed well with experimental results.
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  • 79
    ISSN: 1437-8213
    Keywords: Key words: hydroelastic wave propagation ; frequency response amplitude ; short-term prediction ; reliability analysis system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: This paper deals with the dynamic response and strength of very large floating structures (VLFS) in regular and irregular waves, considering the propagation of the hydroelastic deflection wave of the structure. First, a simplified estimation method is presented for the dynamic response and strength of the structure in regular waves. Then, the validity of the method is demonstrated by comparing its results with analytical results and experimental results for a mat-type floating structure model. Next, a simplified estimation method for dynamic responses under long crested irregular wave conditions is presented by using the above results and by combining them with irregular sea wave spectra. Finally, the applicability of the method is investigated through numerical examples carried out for a 4,800-m class VLFS under trial design. Characteristics of the hydroelastic waves, short-term responses, and reliability levels are numerically identified.
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    Journal of marine science and technology 4 (1999), S. 108-116 
    ISSN: 1437-8213
    Keywords: Key words: computational fluid dynamics, unsteady motion, motion in waves, density function method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: A new computational fluid dynamics simulation method has been developed for the unsteady motion of a ship advancing in waves. The objective is to evaluate the added resistance and predict the performance of a ship in waves. In this study, a finite volume method, in the framework of a boundary-fitted grid system, is employed. The motion of the ship is solved with six degrees of freedom by using the hydrodynamic forces and moments obtained from the solution of the simulation method. The marker–density–function method is employed to calculate the nonlinear free surface. This method is applied to the coupled motion problem of heaving and pitching.
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    Journal of marine science and technology 4 (1999), S. 173-179 
    ISSN: 1437-8213
    Keywords: Key words:H∞ control ; nonlinear system ; ship maneuvering ; saturation element ; ship control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: In designing a control system for large vessels, there are two kinds of nonlinearities which must be considered. One is the nonlinearity in equations of motion and the other is the saturation in control devices such as engine output or rudders. These nonlinearities can strongly affect the performance of the control system. A new method to deal with the nonlinearity of saturation has been proposed in this paper. The saturation is considered as a variation of gain in the system. A control system with gain variation can be designed by H ∞ control theory. As an example, a course-keeping control system for a course-unstable ship has been presented. The results show that the method proposed is effective.
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    Journal of marine science and technology 4 (1999), S. 155-162 
    ISSN: 1437-8213
    Keywords: Key words: microbubble ; bubble ; turbulence ; drag ; frictional resistance ; boundary layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: The time-averaged velocity and turbulence intensity distributions were measured by a laser Doppler velocimeter in a turbulent boundary layer filled with microbubbles. The void fraction distribution was also measured using a fiber-optic probe. The velocity decreased in the region below 100 wall units with an increase in bubble density. This led to a decrease in the velocity gradient at the wall, which was consistent with a decrease in shearing stress on the wall. The turbulence intensity in the buffer layer increased at a low microbubble density, and then began to decrease with an increasing microbubble density. Based on the present measurements, the mechanism of turbulence reduction by microbubbles is discussed and a model is proposed.
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    Journal of marine science and technology 4 (1999), S. 1-6 
    ISSN: 1437-8213
    Keywords: Key words: ship control ; trajectory planning ; avoiding collision ; evolutionary algorithm ; optimization problems ; guidance system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: By taking into account certain boundaries of the maneuvering region, along with navigation obstacles and other moving ships, the problem of avoiding collisions in navigation traffic areas was reduced to a dynamic optimization task with static and dynamic constraints. In heavy navigation traffic areas and within coastal zones, correct selection of a ship's speed, when accompanied by the necessary trajectory changes, is a crucial element of safe navigation. This paper presents a modernized version of the evolutionary ship trajectory planning system in which a new parameter was introduced, namely changes of the ship's speed along particular sections of the trajectory. Generally, a safe trajectory is estimated using specialized genetic operators for modifying the trajectory. Here, an additional operator was added to the system that mutates the ship's speed. Sample results present the safe trajectory for a ferry meeting other moving ships and navigational constraints on its way.
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    Journal of marine science and technology 4 (1999), S. 7-15 
    ISSN: 1437-8213
    Keywords: Key words: nonlinear waves ; wave resistance ; free-surface flow ; computational fluid dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract: A finite difference method based on the Euler equations is developed for computing ship waves and wave resistances. Time marching is carried out using a time-splitting fractional-step method. The second-order central difference is used to discretize the spatial differentials, while the convection terms are discretized by the QUICK scheme. A body- and free-surface-fitted grid system with a cell-centered stencil is used. A Poisson equation for the pressure increment at each time step is solved to enforce mass conservation. The method is validated by comparing the numerical results with the experimental data for a Wigley parabolic hull. The characteristics of ship waves, such as the wave profile along the hull, the wave pattern on the free surface, the pressure distribution on the hull surface, and the wave-making resistance are reasonably predicted. The calculated results are in good agreement with the experimental data.
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    Forschung im Ingenieurwesen 64 (1999), S. 291-295 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Zusammenfassung Der eingeschnürte bzw. engste Strömungsquerschnitt (Vena Contracta) bei der Strömung von Wasser, Luft und von Luft/Wassergemischen durch scharfkantige, kurze Blenden in Rohren wurde gemessen. Bei unterkritischer Einphasenströmung liegt die Kontraktionszahl zwischen 0,62 und eins. Bei Zweiphasenströmung stellt sich eine Kontraktion nur bei Blasen- und bei Sprühströmung ein.
    Notes: Abstract The flow contraction through sharp-edged short orifices respectively the narrowest flow cross-section or the vena contracta has been measured for water, air and air/water mixture. The results demonstrate that the contraction in the case of subcritical single-phase flow is restricted to values between 0.62 and one, while in the two-phase flow it is limited to very narrow ranges of air mass flow qualities where the flow regime is specified as bubbly or spray.
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    Forschung im Ingenieurwesen 64 (1999), S. 296-306 
    ISSN: 1434-0860
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    Description / Table of Contents: Zusammenfassung In der vorliegenden Arbeit wird ein Verfahren zur Lösung der eindimensionalen inversen Wärmeleitungsprobleme dargestellt. Temperaturabhängige Stoffwerte und eine Randbedingung an der leicht zugängigen Außenoberfläche des Körpers sind bekannt. Die Temperatur und die Wärmestrodichte an der Innenoberfläche werden aus dem gemessenen zeitlichen Temperaturverlauf im inneren Punkt der Wand bestimmt. Aus der Lösung des inversen Problems erhält man die Temperaturverteilung in der Wand, die zur Berechnung der Wärmespannungen über Ort und Zeit verwendet wird. Die Berechnung der Temperatur und Spannungsverteilung nach dem vorgeschlagenen Verfahren ist nicht aufwendig und kann online durchgeführt werden. Drei Beispiele bestätigen, daß die vorgeschlagene Methode stabile und genaue Ergebnisee bringt und sich auf zwei- und dreidimensionale Probleme in einfacher Weise erweitern läßt.
    Notes: Abstract A new space marching method is presented for solving the one-dimensional nonlinear inverse heat conduction problems. The temperature-dependent thermal properties and boundary condition on an accessible part of the boundary of the body are known. Additional temperature measurements in time are taken with a sensor located in an arbitrary position within the solid, and the objective is to determine the surface temperature and heat flux on the remaining part of the unspecified boundary. The temperature distribution throughout the solid, obtained from the inverse analysis, is then used for the computation of thermal stresses in the entire domain, including the boundary surfaces. The proposed method is appropriate for on-line monitoring of thermal stresses in pressure components. The three presented example show that the method is stable and accurate.
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    Forschung im Ingenieurwesen 64 (1999), S. 307-316 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Abstract Based on the one-dimensional flow-filament theory on approximation to determine the characteristic lines is presented. Starting from the continuity- and energy equation for the radial- and side channel part, respectively the radial- and side channel stage, the momentum equation together with an energy balance is used to analyze the circulating flow and to obtain the pressure number as a funktion of the delivery number as characteristic size. The results are compared with experiments using water as working fluid. The principle of the combined radial-, side channel is included into the ,,CORDIER“- diagram.
    Notes: Zusammenfassung Auf der Grundlage der eindimensionalen Stromfadentheorie wird eine angenäherte Berechnungsmethode für die Ermittlung der Kennlinien- charakteristiken aufgestellt. Ausgehend von der Kontinuitätsgleichung und des Energiesatzes für den Radial- und Seitenkanalteil bzw. der Radial- und Seitenkanalstufe werden mit Hilfe des Impulssatzes einschließlich einer Energiebilanz die Zirkulationsströmung analysiert und die Druckzahl als Funktion der Lieferzahl als kennzeichnende Größe ermittelt. Zum Vergleich werden Ergebnisse aus experimentellen Untersuchungen an einem Modell mit Wasser als Förderfluid herangezogen. Es erfolgt eine Einordnung des kombinierten Radial-Seitenkanalprinzips in das ,,CORDIER“-Diagramm.
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    Forschung im Ingenieurwesen 64 (1999), S. 317-324 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Abstract Energy systems based on solar collectors or other renewable energy sources are normally regarded as CO2 zero-emission systems because nearly no fossil fuels are used to operate the systems. But the complete evaluation of an energy system concerning its CO2 reduction potential must not be restricted to the emissions during the operation of the system. The cumulative energy demand and the cumulative CO2 emissions during the life cycle have to be considered. In case of a solar collector system, in particular the production-determined emissions and emissions due to the requirement of auxiliary electric power for the collector pump are important. An energy analysis of this kind was performed for solar domestic hot water systems. It is shown that the consideration of the life cycle emissions reduces significantly the CO2 reduction potential of solar collector systems whereby the design of the system has a major influence.
    Notes: Zusammenfassung Solarkollektoranlagen werden ebenso wie andere regenerative Energieanlagen meist als CO2-frei angesehen, da für ihren Betrieb keine fossilen Brennstoffe eingesetzt werden. Die umfassende Beurteilung eines Energiesystems hinsichtlich seines potentiellen Beitrags zur CO2-Minderung darf sich jedoch nicht auf die betriebsbedingten Emissionen beschränken, sondern muß den kumulierten Energieeinsatz und die hiermit verbundenen CO2-Emissionen im gesamten Lebensweg des Systems erfassen. Im Fall einer Solarkollektoranlage zählen hierzu insbesondere die herstellungsbedingten Emissionen und die Emissionen aufgrund des Strombedarfs der Kollektorkreispumpe. Eine solche Analyse wurde für Solarkollektoranlagen zur Brauchwasserbereitung durchgeführt. Es zeigt sich, daß das CO2-Minderungspotential von Solarkollektoranlagen bei Berücksichtigung dieser Emissionen signifikant vermindert wird, wobei die Auslegung der Anlage einen entscheidenden Einfluß besitzt.
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    Forschung im Ingenieurwesen 64 (1999), S. 329-343 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Abstract The characteristic properties for the wetting of a solid by a liquid are the liquid-surface tension σ′, the contact angle ϑ and the solid-surface tension σ‴. For these three properties an empirical equation is developed, which is also applicable to mercury. Many results of various measurements of the three characteristic properties are collected for 14 different solid materials of packing elements and packings. For two above one another lying and two side by side lying particles as spheres or long cylinders the liquid contour was calculated by different authors. Thereby the contact angle was only varied between 0∘ and 90∘. Here the model of Batel [36] for two side by side lying cylinders is extended. The advancing contact angle and the receding contact angle were used. The model was evaluated for contact angles between 5∘ and 175∘. The results shows the importance of the wetting property 0,5( 1 + cos ϑ ).
    Notes: Zusammenfassung Die charakteristischen Größen für die Benetzung eines Feststoffes durch eine Flüssigkeit sind die Flüssigkeits-Oberflächenspannung σ′, der Randwinkel ϑ und die Feststoff-Oberflächenspannung σ‴. Für diese drei Größen wird eine empirische Gleichung aufgestellt, die auch für Quecksilber gilt. Zahlreiche Meßwerte der drei charakteristischen Größen werden für 14 verschiedene Werkstoffe von Füllkörpern und Packungen zusammengestellt. Für zwei übereinander und zwei nebeneinander liegende Teilchen wie Kugeln oder lange Zylinder wurde die Zwickel-Kontur von verschiedenen Autoren berechnet. Dabei wurde der Randwinkel nur von 0∘ bis 90∘ verändert. Das Modell von Batel [36] für zwei nebeneinander liegende Zylinder wird hier erweitert. Dabei werden der Vorrückwinkel und der Rückzugswinkel benutzt. Das Modell wird für Randwinkel von 5∘ bis 175∘ ausgewertet. Die Ergebnisse zeigen die Bedeutung der Benetzungs-Kenngröße 0,5( 1+cosϑ ).
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    Forschung im Ingenieurwesen 64 (1999), S. 325-328 
    ISSN: 1434-0860
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    Description / Table of Contents: Abstract The measurement of mole-fractions for VLE-data points is usually less accurate than measured pressure and measured temperature. Furthermore, the measurement of VLE-data for multi-component mixtures is very time-consuming. To improve the measurements of complete VLE-data points (p,T,{x i },{y i }) an apparatus was developed to take samples of both phases simultaneously from a cell of a VLE-apparatus. With a gas-chromatograph the samples are analysed next to liquid mixtures with known composition to calibrate the analysis. The composition of liquid and vapour phases, can be calculated from the results of gas-chromatic analysis. The developed equations are also valid for calculations of mole-fractions of multi-component mixtures with unlimited number of components.
    Notes: Zusammenfassung Bei der Messung von VLE-Daten sind die gemessenen Werte der Stoffmengenanteile in der Regel mit einer deutlich höheren Unsicherheit behaftet, als der gemessene Druck und die gemessene Temperatur. Zudem stellt die Aufnahme der VLE-Daten von Mehrstoffsystemen häufig ein zeitintensives Problem dar. Zur Verbesserung der Messung von vollständigen VLE-Datensätzen (p,T,{x i },{y i }) wurde ein Probeentnahmesystem entwickelt, das die simultane Entnahme von Proben der flüssigen und gasförmigen Phase aus der Meßzelle einer statischen Phasengleichgewichtsapparatur ermöglicht. Die Proben werden neben den flüssigen Kalibriergemischen mit bekannter Zusammensetzung nach der Entnahme mit einem Gaschromatographen analysiert. Aus den Ergebnissen der Analyse lassen sich unter Berücksichtigung der bekannten Zusammensetzung der Kalibriergemische die Stoffmengenanteile der Komponenten in der flüssigen und gasförmigen Phase berechnen. Die hergeleiteten Beziehungen zur Berechnung der Stoffmengenanteile gelten für Mehrstoffgemische mit beliebig vielen Komponenten.
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    Forschung im Ingenieurwesen 64 (1999), S. 345-359 
    ISSN: 1434-0860
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    Description / Table of Contents: Zusammenfassung Die Kondensation der reinen Kältemittel R12, R134a und ihrer Gemische an einem waagrechten Einzelrohr in freier Strömung wurde experimentell untersucht. Annähernd äquimolare Gemische aus diesen Kältemitteln sind azeotrop. Die Außenfläche des Versuchsrohres war mit einer Kapillarstruktur versehen. Zur Ermittlung der treibenden Temperaturdifferenz wurden Temperaturverläufe längs und am Umfang des Versuchsrohres aufgenommen. Hierzu wurden Thermoelemente in der Rohrwand verschiebbar installiert und das Rohr um seine Achse drehbar in die Anlage integriert. Die mittlere Wandtemperatur, die Dampftemperatur und die aus dem Kondensatstrom gewonnene Wärmestromdichte dienten zur Ermittlung des Wärmeübergangskoeffizienten. Bei der Kondensation reiner Stoffe am verwendeten Rohr ändert sich der Wärmeübergangskoeffizient mit der treibenden Temperaturdifferenz weitgehend in Einklang mit der Nusselt-Theorie. Der Wärmeübergang ist näherungsweise um den Faktor 2 besser als der am vergleichbaren Glattrohr entsprechend dieser Theorie. Das Kältemittel R134a weist unter vergleichbaren Bedingungen einen um etwa 10 bis 15% besseren Wärmeübergang als R12 auf. Der Wärmeübergang von Gemischen hängt entscheidend von den Zusammensetzungen der Phasen ab. Je stärker die Zusammensetzungen der Phasen voneinander abweichen, um so schlechter ist der Wärmeübergang; die Wärmeübergangskoeffizienten liegen stets unterhalb denen des reinen R134a. Im Bereich niedriger Temperaturdifferenzen nimmt der Wärmeübergangskoeffizient bei Gemischen mit der Temperaturdifferenz zu. Dies ist der Bereich der Partialkondensation. Im Bereich größerer Temperaturdifferenzen findet Totalkondensation des Gemisches statt und der Wärmeübergang folgt qualitativ der Nusselt-Theorie.
    Notes: Abstract We experimentally studied free convection condensation heat transfer of pure refrigerants R12, R134a, and their mixtures on a horizontal single tube. Approximately equimolar mixtures of these refrigerants are azeotropic. The outside surface of the tube used had a capillary structure. The tube was integrated in an experimental set-up in a way that allowed its rotation around the axis. Movable thermocouples inserted in the tube wall enabled the determination of the average surface temperature. This temperature, the vapour bulk temperature, and the heat flux obtained from condensate collection served for the determination of the heat transfer coefficient. The condensation heat transfer of the pure refrigerants examined is observed to change with the driving temperature difference largely in accordance with the Nusselt theory. The experimental values of the heat transfer coefficient on the tube used, however, are by a factor of 2 larger than those on a smooth tube according to this theory. Under comparable conditions, the refrigerant R134a shows by 10 to 15% better heat transfer than R12. The heat transfer of mixtures decisively depends on the compositions of their phases. Basically, the stronger the compositions of the phases differ from each other, the lower the heat transfer coefficients; they always lie below those of R134a. In the range of low temperature difference, the heat transfer coefficient of mixtures increases with the temperature difference. This is the region of the so-called partial condensation. At a larger temperature difference, a local total condensation of the mixtures takes place and the heat transfer qualitatively follows the Nusselt theory.
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    Forschung im Ingenieurwesen 65 (1999), S. 13-19 
    ISSN: 1434-0860
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    Description / Table of Contents: Abstract An one-stage radial centrifugal turbine was designed. Measurements of energy characteristics for different number of gude vanes as well as different turbine rotor-types were performed with air. The results of the measurements are presented dimensionless in the shelldiagrams. The experimental data were used in Cordier Diagramm to obtain the relevant comparison to other turbine types. Finally, the particular turbine losses were determined and the Coriolis-force-effect estimated.
    Notes: Zusammenfassung Gebaut wurde eine einstufige, radiale und zentrifugale Versuchsturbine. Die Messungen der Energiekennlinien wurden mit Luft durchgeführt für drei verschiedene Leitschaufelzahlen, sowie für drei Laufradprofile. Die Meßergebnisse werden in dimensionslosen Muscheldiagrammen dargestellt. Die gemessenen Werte sind in einem Cordier Diagramm eingetragen, um einen Vergleich mit anderen Strömungsmaschinen vorzunehmen. Anhand der Verlustanalyse wird versucht, den Einfluß der Corioliskraft näher zu bestimmen.
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    Forschung im Ingenieurwesen 65 (1999), S. 1-12 
    ISSN: 1434-0860
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    Description / Table of Contents: Abstract The expansion flow of this breaker mass flow of side channel compressors decisively influences the intake flow of the gas mass flow in the side channel and so affects the energy transfer and the increase of pressure in the front area of the side channel. This causes a decrease of pressure and losses in this area. By taking measurements of the dynamic pressure fluctuations in the side channel it could be shown that in this area of the side channel the greatest pressure oscillations and with that the highest root main square of the dynamic pressure oscillation occure which finally lead to vortex formation with great losses of pressure. For this reason a decrease of pressure in the inlet area of the side channel is caused which leads to reduction of the increase of pressure. Suggestions for the improvement of the contour of the inlet of the side channel with less decrease of pressure and density are made.
    Notes: Zusammenfassung Die Expansionsströmung des Unterbrechermassenstromes in Seitenkanalverdichtern beeinflußt entscheidend die Eintrittsströmung des Gasmassenstromes im Seitenkanal und beeinträchtigt dadurch die Arbeitsübertragung und die Drucksteigerung im ersten Bereich des Seitenkanals. Dadurch kommt es in diesem Bereich zu Druckabsenkungen und zu Verlusten. Durch Messung der dynamischen Druckschwankungen im Seitenkanal konnte nachgewiesen werden, daß in diesem Bereich des Seitenkanals die größten Druckschwingungen und damit auch die höchsten Effektivwerte der dynamischen Druckschwingung auftreten, die schließlich zur Wirbelbildung mit großen Druckverlusten führen. Dadurch wird die Druckabsenkung im Eintrittsbereich des Seitenkanals hervorgerufen, die zur Verminderung der Druckerhöhung führt. Vorschläge zur Verbesserung der Eintrittskontur des Seitenkanals mit verminderter Druck-und Dichteabsenkung werden unterbreitet.
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    Forschung im Ingenieurwesen 65 (1999), S. 21-30 
    ISSN: 1434-0860
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    Description / Table of Contents: Abstract Thermodynamic evaluation of energy conversion processes requires all energy and entropy fluxes to be known. The basic equations to calculate radiation entropy and the major input functions, namely the spectral and hemispherical distribution of radiation intensity and its degree of polarization, are presented. Furthermore, the entropy production rate due to interaction between radiation and condensed matter is calculated. Minimization of the entropy production rate can be achieved by means of the balance equations.
    Notes: Zusammenfassung Die thermodynamische Beurteilung von Energiewandlungsprozessen erfordert die Kenntnis der mit den jeweiligen Energieströmen einhergehenden Entropieströme. Es werden die Grundlagen zur Berechnung der Strahlungsentropie und der Einfluß der Spektralverteilung, der Richtungsabhängigkeit und des Polarisationsgrades der Strahlung dargestellt. Desweiteren wird die Berechnung der Entropieerzeugungsrate bei der Wechselwirkung zwischen Strahlung und Materie mit Hilfe der Energie- und der Entropiebilanz für diesen Vorgang erläutert. Abschließend wird auf Möglichkeiten zur Minimierung der Entropieerzeugungsrate eingegangen.
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    Forschung im Ingenieurwesen 65 (1999), S. 31-39 
    ISSN: 1434-0860
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    Topics: Technology
    Description / Table of Contents: Zusammenfassung Der Aufsatz fußt auf einem früheren Vorschlag des Verfassers, eine neue Temperaturskala – nach Boltzmann genannt – einzuführen. Nachdem der Vorschlag kurz wiederholt wird, werden einige praktische Konsequenzen aufgezeigt. Insbesondere nimmt das Gesetz für ideale Gase eine einfachere Form an und die molaren Wärmekapazitäten werden zu dimensionslosen Größen. Die universelle Gaskonstante sowie die Boltzmannkonstante werden als überflüssige Umrechnungsfaktoren ausgewiesen. Es wird aufgezeigt, wie eine empirische Skala für die Boltzmanntemperatur hergestellt, und wie mit der neuen Skala Dimensionsanalyse betrieben werden kann. Einige Beispiele aus der statistischen Mechanik belegen, daß die Boltzmanntemperatur bei der Ableitung der grundlegenden Beziehungen gute Dienste leistet. Es wird hervorgehoben, daß der Vorschlag keinen Beitrag zur Theorie der Thermodynamik bringt, sondern lediglich Konsequenzen aus bekannten Tatsachen zieht. Die Boltzmannkonstante wird in der traditionellen Thermodynamik unter Verwendung der barometrischen Höhenformel gemessen. Eine solche Messung ist mit der Boltzmanntemperatur gegenstandslos. Das Ergebnis ist in dieser Betrachtung die Loschmidt-Zahl. Die molare Entropie erweist sich bei Verwendung der Boltzmanntemperatur als eine reine, dimensionslose Zahl, was ihrer Natur am ehesten entspricht. Der Zusammenhang mit der thermodynamischen Wahrscheinlichkeit eines Zustandes wird aufgezeigt. Eine neue Schreibweise der Boltzmannbeziehung: S = k ln W wird angeführt.
    Notes: Abstract The article is based on a previous suggestion by the author to introduce a new temperature scale – named after the German physicist Boltzmann. The proposition is repeated in short, then some practical consequencies are demonstrated. The ideal gas law will take on a simpler form and the molar heat capacities will turn into dimensionless quantities. The universal gas constant and the Boltzmann constant are shown to be superfluous conversion factors. It is further demonstrated how an empirical scale for the Boltzmann temperature can be established and how dimensional analysis can be performed. Some examples from statistical mechanics show that the Boltzmann temperature is well suited when deducing the basic relations in this field. It is emphasized that the proposition does not affect the theory of thermodynamics, it only draws conclusions from well known facts. In traditional thermodynamics the so-called barometric equation is taken to actually measure the Boltzmann constant. Such measurement has no meaning in the Boltz-mann temperature idiom, the result of the measurement is in this notion the Loschmidt (Avogadro) number. The molar entropy becomes a pure, dimensionless number, a property which corresponds well to the real nature of entropy. The relation to the thermodynamic probability of a state is established, and a different form of the Boltzmann equation S=k ln W is given.
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    Forschung im Ingenieurwesen 65 (1999), S. 91-92 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
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    Forschung im Ingenieurwesen 65 (1999), S. 41-47 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Abstract Correlations for the design of side channel machines as pump and compressor are presented, wish allow the calculation of the geometry of the fluid leading components. Sample calculations demonstrate the use of those correlations as well as comparative considerations regarding radial turbo engines. The considerations are based on the use of the “CORDIER”-diagram together with the corresponding characteristic numbers.
    Notes: Zusammenfassung Zur Auslegung von Seitenkanalmaschinen als Pumpe und Verdichter werden Beziehungen zur Ermittlung der geometrischen Abmessungen der fluidführenden Bauelemente aufgestellt und hierzu Zahlenbeispiele eingefügt. Es schließen sich Vergleichsbetrachtungen zu radialen Strömungsmaschinen an. Als Grundlage hierzu dient das „CORDIER“-Diagramm mit den dazu definierten Kennzahlen.
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  • 98
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    Forschung im Ingenieurwesen 65 (1999), S. 91-92 
    ISSN: 1434-0860
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    Forschung im Ingenieurwesen 65 (1999), S. 48-57 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Abstract Scale effects on cavitation phenomena are departures from the classical similarity rules (Thoma number) due to variations in water quality (tensile strength, number and size of nuclei) and Reynolds number (size, flow velocity, viscosity). These scale effects are especially important in the prediction of the prototype cavitation behaviour based on model tests. The presented results obtained on different bodies in test-sections and verified on an impeller show that, after water quality effects have been removed from experimental investigations, clear scaling relations are revealed.
    Notes: Zusammenfassung Bei Kavitationserscheinungen werden Abweichungen von der klassischen Definition der dimensionslosen Kavitationszahl nach Thoma infolge unterschiedlicher Wasserqualität (Zugspannungsfestigkeit, Keimspektrum) und Reynoldszahl (Größe, Strömungsgeschwindigkeit, Viskosität) unter dem Begriff Maßstabseffekte zusammengefaßt. Diese Maßstabseffekte sind insbe- sondere bei der Übertragung von Modellversuchsergebnissen auf die reale Ausführung zu berücksichtigen. Die dargestellten Ergebnisse, welche an stillstehenden Körpern ermittelt und an einem Pumpenlaufrad überprüft wurden, zeigen, daß klare Beziehungen für die Maßstabseffekte abgeleitet werden können, wenn der Einfluß der Zugspannungsfestigkeit berücksichtigt wird.
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    Forschung im Ingenieurwesen 65 (1999), S. 107-112 
    ISSN: 1434-0860
    Source: Springer Online Journal Archives 1860-2000
    Topics: Technology
    Description / Table of Contents: Zusammenfassung Viele Knickprobleme mit strukturellen Verzweigungen weisen eine Skalierungseigenschaft oder Potenzgesetz-Abhängigkeit auf. Mittels einer Dimensionsanalyse wird die allgemeine Skalierungseigenschaft untersucht. Das Konzept einer neuen dimensionslosen Kennzahl, der Antwort-Zahl (response number), die der Autor für die dynamische Plastizierung und das Versagen von Balken,Platten, usw. unter großen dynamischen Lasten vorgeschlagen hat, wird in der vorliegenden Arbeit verallgemeinert und zur Untersuchung von statischen und dynamischen Problemen des elastischen und plastischen Knickens von Stäben, Platten und Schalen angewendet. Strukturelle Verzweigungen bei allgemeinen Knickproblemen treten auf, wenn die Antwort-Zahl einen kritischen Wert erreicht hat.
    Notes: Abstract Many structural bifurcation buckling problems exhibit a scaling or power law property. Dimensional analysis is used to analyze the general scaling property. The concept of a new dimensionless number, the response number-Rn, suggested by the present author for the dynamic plastic response and failure of beams, plates and so on, subjected to large dynamic loading, is generalized in this paper to study the elastic, plastic, dynamic elastic as well as dynamic plastic buckling problems of columns, plates as well as shells. Structural bifurcation buckling can be considered when Rn(n) reaches a critical value.
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