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  • Articles  (2,746)
  • Springer  (2,491)
  • Wiley  (255)
  • MDPI Publishing
  • Oxford University Press
  • 1985-1989  (2,746)
  • Technology  (2,746)
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  • Articles  (2,746)
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  • 1
    Electronic Resource
    Electronic Resource
    Offsets of curves on rational B-spline surfaces (1989)
    Springer
    Engineering with computers 5 (1989), S. 39-46 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The construction of offset curves is an important problem encountered often in design processes and in interrogation of geometric models. In this paper the problem of construction of offsets of curves lying on the same parametric surface is addressed. A novel algorithm is introduced, whose main feature is the use of geodesic paths to determine points of the offset. The offset is then approximated in the underlying surface parameter space by B-splines interpolating data points obtained by traveling a known distance along the geodesics departing from corresponding points of the progenitor in a direction perpendicular to the latter. A comprehensive error checking scheme has been devised allowing adaptive improvement of the approximation of the offset. The applicability of the algorithm is demonstrated by number of numerical examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01201996
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  • 2
    Electronic Resource
    Electronic Resource
    Factors that affect planning in a knowledge-based system for mechanical engineering design optimization with application to the design of mechanical power transmissions (1989)
    Springer
    Engineering with computers 5 (1989), S. 47-62 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Intelligent computer-aided design (CAD) emulates the human activity of design so that production planning, decision making, and inventive design can be performed by computers. Based on the history of human experience in engineering design, a formalized and systematic approach to design should include procedures from (1) conceptual design, (2) layout design, and (3) numerical optimization. The highest level within such a system should be responsible for specifying and symbolically optimizing skeleton structures of generic (nonspecific) elements within the design process that are eventually to be specified uniquely (pinned down) and ultimately optimized numerically. Planning plays a key role in such a system. Planning has been utilized as a tool for process organization within the knowledge domains of chemical engineering, electrical engineering, manufacturing, as well as for general problem formulation and solution. State estimation, subtask scheduling, and constraint propagation have been found to be factors of prime importance in this type of problem. Problems associated with the implementation of a planning strategy within a knowledge-based system for mechanical engineering design optimization are discussed. A hypothesis for planning is put forth and examined within the context of a model of the mechanical design optimization process. An example that demonstrates the applicability of this approach to mechanical power transmission design is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01201997
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  • 3
    Electronic Resource
    Electronic Resource
    Object-oriented knowledge frameworks (1989)
    Springer
    Engineering with computers 5 (1989), S. 79-89 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper introduces a strategy for the construction of object-oriented knowledge frameworks. Global control programs, which are traditionally used for manipulating structured representations, have been replaced by domain-specific resources. This new approach offers increased efficiency and simplified development of knowledge-based expert systems for problem domains that deal with a variety of complex structured information. A theoretical foundation is laid for the representation of knowledge, starting with the adoption of a simple schema for structuring stereotypical information. Data and method abstraction is achieved by installing knowledge frames into part of an object-oriented class system that supports procedural attachment and object communication. This allows frame specialization using domain-specific resources and subsequent construction of modular systems with these specialist frames. Editors are introduced for the alteration of data primitives used in declarative representation. Algorithms, which operate on these data primitives, are given for frame instantiation, data access, and user-directed inference. Examples from structural engineering are used throughout the paper to illustrate the practical application of object-oriented knowledge frameworks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01199071
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  • 4
    Electronic Resource
    Electronic Resource
    Improved optimum structural design by passive control (1989)
    Springer
    Engineering with computers 5 (1989), S. 13-22 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The problem of optimum structural design by passive control is stated in a nonlinear programming form. A solution procedure, based on a successive selection of design and control variables, is presented. Neglecting the implicit analysis equations, the solution becomes independent of the control variables and a lower bound (LB) on the optimum can easily be obtained. The control variables are then selected to satisfy all constraints. If this cannot be achieved, the LB constraints are modified and the control variables are chosen for the revised optimal design. These two steps are repeated until the final optimum is reached. Employing the proposed procedure on various structural systems subjected to static loads showed that the final optimum has been achieved after a very small number of iteration cycles. The numerical examples illustrate a solution with two types of control devices: a linear spring device and a limited displacement device. It has been found that the final optimum is often identical or close to the initial LB solution. Savings of 14 to 63 percent in weight, compared with conventional optima without control, have been demonstrated for some common structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01201994
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  • 5
    Electronic Resource
    Electronic Resource
    An expert system for field inspection of concrete dams: Part 1, engineering knowledge (1989)
    Springer
    Engineering with computers 5 (1989), S. 23-38 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper covers in more detail the material that was introduced in Ref. [1] and describes the final engineering reasoning and knowledge used for an expert system to assist during the field inspection of existing concrete dams. The knowledge base of this expert system was created by combining the traditional expert system approach with the reasoning procedures of qualitative physics. The traditional expert system approach was used to identify the shallow knowledge pertaining to the problem, and qualitative physics was used to identify the deep knowledge. The deep knowledge structured and organized the identification and representation of the shallow knowledge. The expert system uses shallow knowledge to combine a qualitative expert reasoning with a quantitative procedural evaluation of the stability of a dam. The present paper concentrates on the description of the engineering knowledge and Ref. [2] will concentrate on the artificial intelligence issues associated with the knowledge acquisition and representation associated with this expert system. The validation process compared results obtained by the expert system with those obtained by independent field inspection experts. Some of the results are presented here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01201995
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  • 6
    Electronic Resource
    Electronic Resource
    An expert system for setting time steps in dynamic finite element programs (1989)
    Springer
    Engineering with computers 5 (1989), S. 205-219 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract An expert system, ETUDES—Expert Time integration control Using Deep and Surface Knowledge System, which addresses the determination of the timestep for time integration of linear structural dynamic equations is described. This time-step may also be applicable for a moderately nonlinear simulation of the same structure. The program also determines whether an explicit or implicit method is most efficient for the particular simulation. A production rule programming system written in OPS5 is used for the implementation of this prototype expert system. Issues relating to the expert system architecture for this application, such as knowledge representation and structure, as well as domain knowledge are discussed. The prototype is evaluated by measuring it's performance in various benchmark model problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274213
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  • 7
    Electronic Resource
    Electronic Resource
    h andh-p version error estimation and adaptive procedures from theory to practice (1989)
    Springer
    Engineering with computers 5 (1989), S. 221-234 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this paper we introduce techniques that allow us to define a posteriori error estimators via well-known recovery techniques. These allow us to construct a posteriori error estimators for relatively general problems. Further, we introduce new adaptive procedures that make use of these estimators and, in particular, describe anh-p procedure that is simple to implement and that, as numerical experiments have shown, attains an accelerated rate of convergence expected from theh-p version.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274214
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  • 8
    Electronic Resource
    Electronic Resource
    Announcement (1989)
    Springer
    Engineering with computers 5 (1989), S. 259-259 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274217
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  • 9
    Electronic Resource
    Electronic Resource
    AnO(N) algorithm to automatically generate geometric triangulations satisfying the Delaunay circumsphere criteria (1989)
    Springer
    Engineering with computers 5 (1989), S. 177-193 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper presents an algorithm for the generation of Delaunay triangulations for general nonmanifold geometric models. Octree concepts are used for point placement and providing the linear, with respect to the number of elements, growth rate of the algorithm. Compatibility and classification procedures are used in conjunction with point injection procedures to ensure that the final Delaunay triangulation is a geometric triangulation of the domain of interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274211
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  • 10
    Electronic Resource
    Electronic Resource
    Automatic mesh generation for complex three-dimensional regions using a constrained Delaunay triangulation (1989)
    Springer
    Engineering with computers 5 (1989), S. 161-175 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper describes a method for generating tetrahedral meshes. The algorithm, based on the Delaunay triangulation, can treat objects of essentially arbitrary complexity. In order to preserve the surface triangulation of solid objects, it is necessary to override the Delaunay property and redefine the triangulation when points are introduced that are close to solid boundaries. Details of this constrained Delaunay algorithm are presented and an efficient implementation of the triangulation method is described. Techniques for controlling the distribution of mesh points and tetrahedron quality are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274210
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  • 11
    Electronic Resource
    Electronic Resource
    Knowledge-based control for finite element analysis (1989)
    Springer
    Engineering with computers 5 (1989), S. 195-204 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper shows that control logic may be separated from analysis software and that a knowledge-based expert system can use this logic to perform interactive computation. Heuristics that control a simple interactive finite element analysis program are represented using a rule-based format and are used by a goal-driven logic processor to invoke analysis activity. Traditional algorithm-oriented control and the proposed knowledge-based control are compared in a simple displacement computation scenario to identify the advantages/disadvantages of the two approaches. General activities and constraints, practical methods of reasoning and representation, and knowledge-based expert systems are discussed with emphasis on applications to interactive finite element analysis. An analysis control expert system has been developed for use in the numerical analysis of two-dimensional linear problems in solid and structural mechanics. An example problem is used to clarify the methods used to direct activity and to identify the problems associated with conditional task processing for interactive analysis. The main difference between the analysis program described in this paper and conventional analysis programs is related to the control architecture. The general conclusion of this paper is that knowledge-based control is more effective and flexible than algorithm-oriented control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274212
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  • 12
    Electronic Resource
    Electronic Resource
    Adaptive multiple-levelh-refinement in automated finite element analyses (1989)
    Springer
    Engineering with computers 5 (1989), S. 235-247 
    Details
    ISSN: 1435-5663
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper discusses an automatic, adaptive finite element modeling system consisting of mesh generation, finite element analysis, and error estimation. The individual components interact with one another and efficiently reduce the finite element error to within an acceptable value and perform only a minimum number of finite element analyses. One of the necessary components in the automated system is a multiple-level local remeshing algorithm. Givenh-refinement information provided by an a posteriori error estimator, and adjacency information available in the mesh data structures, the local remeshing algorithm grades the refinement toward areas requesting refinement. It is shown that the optimal asymptotic convergence rate is achieved, demonstrating the effectiveness of the intelligent multiple-level localh-refinement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274215
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  • 13
    Electronic Resource
    Electronic Resource
    Therapeutic laser guidelines: On the effects of laser radiation on human skin-fibroblast metabolism in culture (1989)
    Springer
    Lasers in medical science 4 (1989), S. 31-40 
    Details
    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Summary A promising field of laser utilization is the modification of cell behaviour. Acting on cell biological functions it might be possible to use them to improve medical therapies. This possibility suggests investigation of dosimetry guidelines employing different wavelenghts, power and exposure durations for future potential use of lasers in medicine. In this line of investigation, structural organization and viability of fibroblast has been studied, thus observing that the cell number remains unaltered by low density laser irradiation. Nevertheless, results observed in metabolism variation suggest that, with appropiate irradiation-protocol an efficient modality for enhancement or modulation of cell activity can be found, and thereafter used for therapeutical pourposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276668
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  • 14
    Electronic Resource
    Electronic Resource
    Experimental effects of Argon and CO2 lasers on skin and vessels (1989)
    Springer
    Lasers in medical science 4 (1989), S. 95-103 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Summary Response of rabbit ear blood vessels and defects on the pig skin to Argon and CO2 lasers, (1 to 4 Watts and 0,1 to 0,2 sec pulses), were analysed. Examining lesion depth and its diameter, it was seen, using both lasers, that when power and time exposure increased, lesion depth increased as well, At the same time, when power was increased and the time of irradiation was constant, the diameter of the lesion remained approximately the same. Histologically, by using Argon laser at 1'5 W, there is no evidence of skin lesion but vessel coagulation occurs. On the other hand, more power (3 to 4 W) produces skin destruction. CO2 laser at 1'5 W causes skin destruction while 3 W penetrates deeper, cutting all tissues and producing vessel-wall fragmentation and haemorrhage. In contrast to CO2 laser, which definitly stops blood circulation by cutting the vessels, Argon laser entails many recurrences and vessels re-start circulation; a fact which is not desirable in cutaneous vascular disorders treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276673
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  • 15
    Electronic Resource
    Electronic Resource
    The present state of safety laws and regulations in the FRG (1989)
    Springer
    Lasers in medical science 4 (1989), S. 213-213 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276688
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  • 16
    Electronic Resource
    Electronic Resource
    Title: Development of national safety regulations for medical use of lasers in the Netherlands (1989)
    Springer
    Lasers in medical science 4 (1989), S. 235-238 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Until now there are no national safety regulations for the medical use of lasers in the Netherlands. However, a committee of experts from hospitals, Health Council of the Netherlands, TNO Medical Technology Unit and industry is preparing recommendations. Their work is based on MPE values and special measurements that are performed to assess divergence and intensity distribution of laser beams, as well as optical and thermal properties of materials that are used in the clinical setting. The final intention of the committee is to advise government and hospitals on technical, environmental and administrative measures for the safety of the various medical laser applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276691
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  • 17
    Electronic Resource
    Electronic Resource
    The accident prevention regulation “Laser Radiation” (VGB 93) — Special regulations for the safe use of laser products in the Federal Republic of Germany (1989)
    Springer
    Lasers in medical science 4 (1989), S. 243-249 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Accident prevention regulations, e.g. VBG 93 “Laser Radiation”, are a national particularity in the FRG. The regulations issued by the injuries insurance institutes are binding upon employers and employees. The apparatus and equipment safety law makes the VBG 93 obligatory also for manufacturers and importers. National and international standards are referred to in relevant context in the VBG 93. The VBG 93 is also used by the governmental authorities for the protection of labour. The medical apparatus decree has to be observed also for medical application. Some important aspects of the VBG 93 will be described in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276693
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  • 18
    Electronic Resource
    Electronic Resource
    Proposal for dosimetry of non-ionizing radiation (1989)
    Springer
    Lasers in medical science 4 (1989), S. 329-340 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In general “Dose” by itself as an amount of energy is not a relevant parameter for the description of penetration by non-ionizing (laser) radiation. But dosimetry should not only include the measurements of relevant parameters and its relatioships to tissue effects but also include all possibilities of measurements and relationships which help to control the biological result on tissue by irraditation with non-ionizing laser radiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276699
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  • 19
    Electronic Resource
    Electronic Resource
    Laser therapeutic guidelines used in the Lisbon Institute of Ophthalmology (1989)
    Springer
    Lasers in medical science 4 (1989), S. 361-365 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In this paper the Author presents the guidelines of laser therapy in the Lisbon Institute of Ophthalmology, with spetial referance to the laser parameters, the ocular pathology imposing laser therapy and the necessary conditions for safety of the patient and of the doctor, operating with laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276703
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  • 20
    Electronic Resource
    Electronic Resource
    Study of laser-tissue interactions through Raman spectroscopy (1989)
    Springer
    Lasers in medical science 4 (1989), S. 41-61 
    Details
    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A review is presented of Raman spectroscopic applications in the study of laser-tissue interactions. The basic definitions of Raman spectroscopy are given with emphasis to those concepts and techniques which are relevant to biomedical material characterization. Representative problems from current literature will be discussed, like atherosclerosis of human vessels, eye lens aging, formation and diagnosis of cataracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276669
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  • 21
    Electronic Resource
    Electronic Resource
    Comparison of lasers for photodynamic therapy with a phthalocyanine photosensitizer (1989)
    Springer
    Lasers in medical science 4 (1989), S. 7-12 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Three different lasers were compared under the same conditions for their effectiveness at producing photodynamic damage to normal colon following sensitization with aluminium sulphonated phthalocyanine (AlSPc). One laser was an argon ion pumped continuous wave (CW) dye laser and the other two were pulsed at 10 kHz (copper vapour laser pumped dye laser, and 5 Hz (flashlamp pumped dye laser). The CW and 10 kHz laser were equally effective at producing damage. The 5 Hz laser failed to produce a photodynamic effect, although occasionally caused a photomechanical effect when the laser fibre was placed touching the colonic mucosa. Quantitative analysis suggests that the high energy pulses of the flashlamp pumped dye laser saturate AlSPc, so very little of the available energy can be used to produce a photodynamic effect, in contrast to the two other lasers which do not produce saturation conditions.
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    URL: http://dx.doi.org/10.1007/BF02032503
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  • 22
    Electronic Resource
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    Effect of the non-contact mode of YAG laser on pulmonary tissues and its comparison with electrodiathermy: An anatomo-pathological study (1989)
    Springer
    Lasers in medical science 4 (1989), S. 17-23 
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    ISSN: 1435-604X
    Keywords: YAG Laser/Electrodiathermy ; Pulmonary tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract An anatomo-pathological study was undertaken to evaluate the early effects of high and low powered non-contact mode of YAG laser on pulmonary tissue and to compare these effects with those resulting from electro-diathermy. In 40 patients with bronchial carcinoma, thoracotomy was carried out using conventional surgical methods, the part of the lung destined to be excised was then exposed to: Non-contact YAG laser of high or low power (Group A, n=15); cutting/ or coagulation electro-diathermy (Group B,n=15); and mixed (blend) cutting and coagulation electro-diathermy (Group C,n=10). The results indicated that high power non-contact YAG laser is capable of incising the pulmonary parenchyma without bleeding or air leak, only the larger and sub-segmental vessels and bronchial branches needed suturing. This was not the case for electro-diathermy, either in its cutting or blend form. The low power laser was capable of sealing off the superficial bleeding vessels and contracting the alveolar sacs, thus preventing bleeding and air leak. Only the superficial bleeding could be stopped by coagulation diathermy which had no effect in preventing air leak from the parenchyma. Microscopically, apart from evaporation, laser produced charring and coagulative necrosis in the remaining exposed tissue. No evaporation of tissue occurred with electro-diathermy (either in its cutting, blend or coagulation mode). Only a very limited charring and coagulative necrosis was present in the remaining tissues exposed to coagulation electro-diathermy.
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    URL: http://dx.doi.org/10.1007/BF02032505
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  • 23
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    Open lung surgery with Nd-YAG Laser (1989)
    Springer
    Lasers in medical science 4 (1989), S. 13-16 
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    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Open lung surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We report on nineteen patients who successfully underwent open lung performance with a Nd-YAG laser in the period December 1987 to August 1988. Reasons for laser operations were lung metastases (twelve cases), lung fibrosis (five patients), one lung cyst and one tuberculoma. We used the Nd-YAG laser in non-contact mode, with focus hand-piece spot size of 1.5 mm, a continual 1064 nm wavelength and a power output 90 W. In these nineteen cases we performed 35 laser photoablations of lung tissue. All patients healed without any serious complications. The major advantage of Nd-YAG laser beam in open lung surgery is in the rapid sealing effect of small airways and of blood vessels up to 3 mm. The Nd-YAG laser seems to be very suitable for operations in lung periphery.
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    URL: http://dx.doi.org/10.1007/BF02032504
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  • 24
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    Book reviews (1989)
    Springer
    Lasers in medical science 4 (1989), S. 65-65 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02032510
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  • 25
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    Meetings announcements (1989)
    Springer
    Lasers in medical science 4 (1989), S. 71-72 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032512
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  • 26
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    Photodynamic treatment of cholesteatoma of the ear induced experimentally in rabbits: Preliminary report (1989)
    Springer
    Lasers in medical science 4 (1989), S. 111-113 
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    ISSN: 1435-604X
    Keywords: Cholesteatoma ; Haematoporphyrin ; Photo-dynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In a previous project on haematoporphyrin (HP) uptake by experimentally induced cholesteatoma of the rabbit, it was shown that HP concentration was remarkably high in the cholesteatoma, with a peak at three hours after intravenous administration of the drug. On the basis of these results an attempt was made to destroy the matrix of cholesteatoma by means of photodynamic therapy. Cholesteatomas were induced bilaterally in the ears of eight rabbits which were divided into two groups, according to the interval between HP administration (5 mg/kg body weight) and irradiation. The irradiation was carried out with light at 600–680 nm, filtered from the emission a quartz halogen lamp (dose rate 300 mW cm−2; total dose 120 J cm−2). The first group was submitted to photodynamic therapy after three hours and the second after twelve hours. In both groups half the rabbits were sacrificed at 24 h and half at 48 h post-irradiation. Histological studies showed significant vascular lesions, necrosis of the wall of the cholesteatoma, interstitial extravasation of blood, and oedema in a high percentage of the animals. The lesions were much greater in animals sacrificed at 48 h after photodynamic therapy.
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 137-138 
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    Topics: Medicine , Physics , Technology
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    The role of the CO2 laser in out-patient oral surgery (1989)
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    Lasers in medical science 4 (1989), S. 151-154 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The treatments of 250 patients with the CO2 laser is described. The procedures were performed under local anaesthesia with minimal instrumentation apart from the laser. Operations were rapid and relatively bloodless, and excellent cosmetic and functional results were obtained. In the post-operative period there was minimal oedema and no significant bleeding. Post-operative pain was also minimal allowing patients to resume their normal diet on the first post-operative day and to return to work. The experience gained with this first group of patients suggests that ideal cases for treatment by this modality include leukoplakia, haemangiomas, epulis and prosthesis fibromas. The CO2 laser is now being used to a lesser extent on in-patients and on those with malignant lesions.
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    Laser-induced fluorescence used in localizing atherosclerotic lesions (1989)
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    Lasers in medical science 4 (1989), S. 171-181 
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    Keywords: Autofluorescence ; Laser-induced fluorescence ; Laser-induced breakdown spectroscopy ; Atherosclerosis ; Tissue diagnostics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We have investigated laser-induced fluorescence frompost mortem human arteries in order to find spectroscopic properties allowing discrimination between normal and atherosclerotic vessel wall. A pulsed nitrogen laser emitting light at a wavelength of 337.1 nm was used as an excitation source. The fluorescence spectrum from 370 to 700 nm was captured and analysed by an optical multichannel analyser. Dimensionless contrast functions were formed by using characteristic spectral features at 390, 415, 480, 580 and 600 nm. All samples were investigated in scans across a region where normal as well as diseased vessel wall appeared. The types of plaque were histopathologically divided into four groups, of which three could be singled out using one or more of our spectroscopic criteria. We also investigated the different layers of the normal and diseased vessel wall in order to determine the various contributions to the fluorescence signal. Furthermore, plasma emission spectra were recorded while ablating the normal as well as the diseased vessel wall with an excimer laser, emitting radiation at 308 nm, thus detecting the change in spectral characteristics during the ablation process down into deeper layers.
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 203-204 
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    Photodynamic therapy for the treatment of advanced gastrointestinal tumours (1989)
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    Lasers in medical science 4 (1989), S. 183-186 
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    Keywords: Photodynamic therapy ; Gastrointestinal tumour ; Advanced lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In the study, 120 patients with advanced gastrointestinal tumours were treated by PDT; 5 mg/kg of HpD was intravenously given 48–72 h prior to PDT. The light source was an argon dye laser with an output beam of 630 nm. The irradiation time varied from 15–25 min with a power of 100–350 mW cm−2. The entire tumour was irradiated with a light dose of 100–250 J cm−2. Of the 120 patients, 20 had cancer of esophagus, 72 had cancer of the gastric cardia, 18 had cancer of the stomach and 10 had cancer of the rectum. Eighty-eight patients (73.3%) had a response to PDT. Twelve patients with CR were followed up for one to five years, two patients died during the two years after PDT.
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    Identification of brain tumours in rats using laser-induced fluorescence and haematoporphyrin derivative (1989)
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    Lasers in medical science 4 (1989), S. 241-249 
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    Keywords: Brain tumour ; Rat ; Detection ; Fluorescence ; Laser ; Haematoporphyrin derivative
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Laser-induced fluorescence has been used for the identification of brain tumours in rats, which have been previously given tumour-seeking haematoporphyrin derivative. A pulsed nitrogen laser (λ=337 nm) was used in conjunction with an optical multichannel analyzer. For both inoculated RG-2 and TCVC rat-brain-tumour models, the blue autofluorescence was strongly reduced in the tumour compared with normal brain tissue, and at the same time the characteristic red-drug signal increased. The contrast between tumour and normal tissue was strongly enhanced by forming the ratio between the two signals. Implications for possible improvement of tumour delineation in brain tumour surgery are discussed.
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    New laser literature (1989)
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    Lasers in medical science 4 (1989), S. 285-287 
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    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02032461
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    A single transcutaneous light irradiation to injured peripheral nerve: Comparative study with five different wavelengths (1989)
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    Lasers in medical science 4 (1989), S. 259-263 
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    Keywords: Low-level laser irradiation ; Peripheral nerve injury ; Single effect of 632.8, 660, 830, 880 and 950 nm wavelengths
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Twenty rats underwent a crush injury to their sciatic nerve, followed immediately by a single low-power coherent or non-coherent irradiation administered transcutaneously on the projection of an injured peripheral nerve. Five wavelengths were tested: 632.8, 660, 830, 880 and 950 nm. The electrical activities of the crushed nerve, immediately after irradiation and on the following first, third and seventh day post-crush, were compared to the precrush activity. The results indicate that energy at the wavelength of 632.8 nm (CW He-Ne laser), delivered transcutaneously (10 J cm−2 at each point) along the projections of the nerve, prevents the drop in the functional nerve activity as measured by the combined action potential (AP) after crush injury. Other wavelengths were either less effective (660 nm) or totally ineffective under the same conditions. The beneficial effects were temporary and lasted only one day after injury and the single irradiation session.
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    New laser literature (1989)
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    Lasers in medical science 4 (1989), S. 199-202 
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    Report on the photodynamic therapy dosimetry meeting: April 1989 (1989)
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    Lasers in medical science 4 (1989), S. 211-220 
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    Argon laser therapy of port-wine stains—Prediction of the effect by transcutaneous microscopy (1989)
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    Lasers in medical science 4 (1989), S. 237-240 
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    Keywords: Argon laser ; Port-wine stains ; Transcutaneous microscopy
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract Sixty-two consecutive patients presenting with facial port-wine stains were examined by transcutaneous microscopy prior to argon laser treatment. The capillary morphology was classified and the late outcome was independently examined and scored. It was found that capillary appearances do have some value in predicting a favourable response and in predicting scarring.
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    Argon laser treatment of solid Ehrlich carcinoma tumours sensitized with some porphyrin compounds (1989)
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    Lasers in medical science 4 (1989), S. 265-268 
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    Keywords: Argon laser, Photodynamic therapy ; Cancer
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    Notes: Abstract The effect of continuous-wave argon laser radiation on the growth of solid Ehrlich carcinoma was studied in mice. To enhance the tumour sensitivity to laser radiation, compounds of a porphyrin series were given to animals prior to the laser treatment. Out of 14 substances tested, tetraphenylporphyn-sulphonate and its palladium complex had the most pronounced photosensitizing activity comparable with that of haematoporphyrin derivative (HPD). Metallic complexes of tetraphenylporphyn and protoporphyrin were less active. It is concluded that porphyrins are promising sensitizers for photodynamic therapy (PDT).
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    Meetings announcements (1989)
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    Lasers in medical science 4 (1989), S. 289-290 
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    Photodynamic therapy in the treatment of malignant tumours of the upper aerodigestive tract (1989)
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    Lasers in medical science 4 (1989), S. 279-284 
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    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Haematoporphyrin ; Argon dye laser ; Early stage esophageal cancer ; Head and neck cancer ; Squamous cell carcinoma ; Adenocarcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This is the report of a pilot study in which the technique of photodynamic therapy (PDT)—in which malignant tissues are destroyed by light after being previously photosensitized by haematoporphyrin or its derivative—was performed using a high power argon-dye laser system which operated at 630±5 nm and optical fibres with either a microlens or a diffusing tip. A total of thirty-seven patients were utilized for this study, including twenty-five patients affected by esophageal carcinoma, five by recurrences of head and neck cancer, four by gastric cancer and three by lung cancer. Among the sixteen cases with superficial or localized cancer of the esophagus, complete and partial responses were observed in seven and six patients, respectively. In advanced and recurring cancers less satisfactory results were obtained. Thus, PDT seems to be useful in cases of small superficial cancers, either primary or recurrent after previous treatments.
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    Product data models (1989)
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    Research in engineering design 1 (1989), S. 43-50 
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    ISSN: 1435-6066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Product data models can be viewed as a class of semantic data models which take into account the needs of engineering data. In this paper the characteristics for semantic data models defined by Peckham and Maryanski [8] are taken as a starting point. The relevance of these characteristics to product data is shown. The capabilities of a prototype product description system are described in relation to the same characteristics. Additional data modeling characteristics such as parametrization and data sharing, which have been introduced to support engineering design, are then described. These can be viewed as extending beyond the accepted capabilities of semantic data models.
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    A review of research in mechanical engineering design. Part I: Descriptive, prescriptive, and computer-based models of design processes (1989)
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    Research in engineering design 1 (1989), S. 51-67 
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This is the first of a two part paper summarizing and reviewing research in mechanical engineering design theory and methodology. Part I includes: 1) descriptive models; 2) prescrptive models; and 3) computer-based models of design processes. Part II, which will appear in the next issue of this journal, will include: 4) languages, representations, and environments for design; 5) analysis in support of design; and 6) design for manufacture and the life-cycle. For each major area, we discuss the current topics of research and the state of the art, emphasizing recent significant advances. We also discuss the important open research issues in each area. The six categories are certainly not mutually exclusive nor even collectively exhaustive; however, some organization is necessary, and these categories have been effective in making sense of a body of research that is expending rapidly in many exciting and promising directions. The mechanical engineering design research community has made major advances over the last few years. The research community in mechanical engineering design has made significant progress not only in advancing our knowledge of design, but also in clarifying the research methods necessary to study design. Great progress is being made toward a better understanding of design, and hence toward better design tools.
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    Synthesis of schematic descriptions in mechanical design (1989)
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    Research in engineering design 1 (1989), S. 3-18 
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    ISSN: 1435-6066
    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 article describes a schematic synthesis problem and one of its solution techniques. The problem domain consists of devices that can be described as networks of lumped-parameter, idealized elements in the translational-mechanical, rotational-mechanical, fluidmechanical, and electrical media. Such devices include speedometers, accelerometers, pneumatic cylinders, and pressure gauges. Design problems in this domain are specified by an input quantity, an output quantity, and the desired relationship between the input and output. The solution technique is based on three steps: 1) generate a candidate design, 2) derive and classify the behavior of the candidate, 3) based on the derived behavior and domain knowledge, modify the candidate (if possible) to bring it in line with the specification. The key idea behind this techniques is that an abstract characterization of the essential properties of the candidate design expedites the analysis and modification. The results of this work are aimed at computer tools for preliminary mechanical design.
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    CO2 lasers thermal changes on laryngeal tissue after different application modes (1989)
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    Lasers in medical science 4 (1989), S. 83-89 
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    Topics: Medicine , Physics , Technology
    Notes: Summary Standardized operations including incisions and ablations were carried out on pigthroats immediately prior to evaluation of the depths of thermal damage zones measured with a unit of 30 mikrons. The following parameters were applied on the tissue: 1) Continuous versus single pulse mode. 2) equal energy impacts with variation of time and power density. 3) super pulse versus non super pulse. In the 1st series the tissue damage for all tissues examined were significantly lower in the single pulse mode than in the continuous mode. In the 2nd series the pooled material showed a significance in favour of short impacts with high power density although the total energy required for a single operation was up to 40% higher in the high power/short time series. The 3rd series showed no significance in differences between super pulse and nonsuper pulse damage when applying the same average output on the laryngeal tissues involved.
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    Requirements of an up to date fibre optics delivery system for laser medicine (1989)
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    Lasers in medical science 4 (1989), S. 105-109 
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    Notes: Abstract The possibility of the potential as well as the safety of an optical fibre delivery system for laser medical applications is reviewed. Fibre directional couplers and connectors are suggested to be developed in view of this power laser application. Finally a special fibre probe radiating a corolla shaped beam for laser angioplasty is briefly described.
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    Sapphire and metal tip recanalisation: Implications for safety (1989)
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    Lasers in medical science 4 (1989), S. 119-127 
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    Notes: Abstract The characteristics of two modified fiber tips, the metal laser probe and the rounded sapphire contact probe, were examined in vitro and in vivo with respect to some of the risks of laser angioplasty. Both probes have an atraumatic, blunt shape. The laser beam profile of the sapphire contact probe looses its focussing properties in water. In vitro, we found a large temperature gradient from the front to the rim of the probe. Ablative temperatures were reached at the tip whereas the temperature of the metal connector near the rim of the sapphire crystal rose only 30 °C in blood when 15 W Nd-YAG was applied for 1 s. In contrast, the metal laser probe reached temperatures over 500 °C in an in vitro tissue/blood environment when 10 W was applied for 5 s. The metal probe ablated both in the forward and the radial direction. In a rabbit model there was a large variation in temperature of the metal in vivo (70 – 320 °C). The highest temperatures were associated with acute complications. However, in spite of transmural coagulation necrosis the artery wall remained functionally intact during a follow up period of up to 56 days.
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    Medical laser safety in the United Kingdom (1989)
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    Lasers in medical science 4 (1989), S. 177-179 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Following a brief historical introduction the current status of Medical Laser Safety legislation and practise in the United Kingdom is outlined. Manufacturing and Administrative measures are specified both for public hospitals and private clinics
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    Respiration triggered CO2 laser application in the Larynx — a a possibility to reduce the smoke inhalation of patients ? (1989)
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    Lasers in medical science 4 (1989), S. 139-141 
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    Notes: Abstract The following is a report on a CO2 laser-respiration-triggering with its application in the larynx causing a reduction in the smoke load of the patient. From the result observed — an impro — ved suction capability and a reduced smoke-intensity in the ex —pired respiratory gas — it would appear that this method were suitable for practical application.
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    Medical laser in Greece (1989)
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    Lasers in medical science 4 (1989), S. 381-384 
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    Notes: Abstract Although Laser technology has been around in Greece for quite some time, the medical and surgical application of Lasers has only recently started. However, the future seems to be promising due to the existence of advanced Laser Institutes, especially in Crete, the recent creation of the “Greek Medical Laser Society”, the increasing number of well trained physician, in the field of Laser and the expected close cooperation of all of the above.
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    Laser balloon angioplasty: An optical and thermal analysis (1989)
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    Lasers in medical science 4 (1989), S. 63-82 
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    Notes: Abstract Our theoretical assessment of laser balloon angioplasty (LBA) begins with a solution of the popular P1 (diffusion) approximation to the radiative transport equation to map the optical field in an axisymmetric, finite annulus surrounding an infinitely long hollow cylindrical vessel. The inner surface is irradiated by diffuse light at 1.06 μm and delivered by a spiral segment of fiberoptic positioned centrally inside an inflated balloon. The present model considers only a single layer of optically homogenous arterial wall because the hollow is presumbly filled with a non-absorbing and non-scattering fluid. The cylindrical enclosure collects reflected light and redirects it back onto the inner surface. Our model accounts for this ‘integrating’ behavior, unique to enclosures. Absorption of the laser light then raises tissue temperature. The resultant transient and spatial temperature distribution is calculated with an implicit Finite Difference algorithm based on the heat conduction equation. Multiple concentric layers, each with different thermal properties from the other, are considered. However, changes in optical and thermal properties with temperature, and thermal phase transitions have been omitted in the present model. Finally, the Arrhenius rate process integral is applied for damage calculations. The temperature patterns of three delivery dose patterns — constant 22.5W (20s), ramp sequences of 40W(5s)-30W(5s)-10W(10s), and 35W(5s)-25W(5s)-15W(10s) — suggest that the second ramp dose may be most efficacious because it generates the longest temperature ‘plateau’ at the intimal-medial junction. Simulations of a hot metallic probe have a consistently higher surface damage than that obtained by LBA of equivalent energy output.
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    Application of 308 nm excimer laser radiation for ocular surgery — Safety considerations (1989)
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    Lasers in medical science 4 (1989), S. 129-138 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Transmitting 308 nm excimer laser radiation via quartz fibers allows one to perform several surgical procedures inside the eye and on the cornea. A special application tip has been developed for each procedure. 308 nm radiation may damage the lens and the retina of the eye. UV absorbing drugs have been successfully used in in-vitro experiments to reduce the UV exposure of intraocular structures sensitive to 308 nm radiation.
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    Beam delivery systems (1989)
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    Lasers in medical science 4 (1989), S. 155-158 
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    Notes: Abstract Fibre optic systems, micromanipulator optics and articulated arms are described with particular emphasis on safety,limitations and areas of likely failure.
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    Experience with laser safety in the USA-a review (1989)
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    Lasers in medical science 4 (1989), S. 165-175 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Following several research programs in the 1960's aimed at studying the adverse biological effects of lasers and other optical radiation sources, laser occupational exposure limits were set and general safety standards were developed. Today, the experience from laser accidents and the development of new lasers and new applications have altered the format of the exposure limits and the safety procedures. It is critically important to distinguish between different biological injury mechanisms. The biological effects of ultraviolet radiation upon the skin and eye are additive over a period of at least one workday, and require different safety procedures. The scattered UV irradiance from excimer lasers may be quite hazardous, depending upon wavelength and action spectra. Since laser technology is young, the exposure of an individual in natural sunlight must be studied to evaluate the potential for chronic effects. The safety measures necessary in the use of lasers depend upon a hazard evaluation. The appropriate control measures and alternate means of enclosure, baffling, and operational control measures are presented. Present laser safety standards are explained briefly. Eye protective techniques and eyewear are considered for a variety of sources. The optical properties of enclosure materials are also discussed.
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    Laser safety regulations and recommendations in Denmark (1989)
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    Lasers in medical science 4 (1989), S. 201-204 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The Danish National Regulations are worked out by The Ministry of Labour. The regulations are not expressed in a clear form and guidelines for laser use in medical treatment rest more or less on the interpretation of legal and ethical regulations for medical personnel applicable in other areas. These regulations will be presented. Common Laser regulations for the EEC in cooperation with the ELA are suggested.
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    Laser Safety Standards and Safety Regulations for medical practise (1989)
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    Lasers in medical science 4 (1989), S. 229-234 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A short survey on the development of the Laser Safety Regulations and Standards in the GDR is given. The last step is the adaptation of the IEC 325 document as the basis of national Laser Safety Standards. This basis is completed by guide-lines covering the general national requirement as well as special regulations for safe use of lasers in medical practise.
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    French standards on medical laser equipment (1989)
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    Lasers in medical science 4 (1989), S. 253-259 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In France, the safety problems resulting from the therapeutic use of Laser are controled by two Standards NFC 74-311 and 312 These one are analysed. On the other hand an User's Guide which will be in the next edition as as appendice of the NFC 74-312 Standard is presently under consideration by the French committe. This one is analysed.
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    New directions in Medical laser concept: role of laser-tissue interaction modelization and feedback control (1989)
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    Lasers in medical science 4 (1989), S. 317-327 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Thermal lasers are used in many specialties. Clinical use of lasers is complicated by variations in tissue characteristics or hazards such as movement. Pionners in this field, relying on experimental work, have mastered the therapeutic use of lasers. Nevertheless, teaching such poorly defined technique has proved to be very difficult. To widespread the use of lasers, it is necessary to work in new directions. The goal is to give the practitioner a real medical tool, which should be cheap, easy and safe to use.
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    Endoscopic laser therapy (E.L.T.) at the National Cancer Institute, Milan: Current trends and new ideas (1989)
    Springer
    Lasers in medical science 4 (1989), S. 351-358 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Presently, ELT is used 1) for the palliation of symptoms related to advanced cancer and 2) for the cure of benign tumors, vascular lesions, and early cancers in high surgical risk patients. The clinical use of new laser applications such as lithotripsy, hyperthermia, fluorescence, and tissue welding will parallel the development of new technologies in laser sources, optic fibers, and endoscopes.
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    Laser training and accredentiation in Denmark (1989)
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    Lasers in medical science 4 (1989), S. 375-379 
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    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02276706
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    Fields of training in the Laser Platform of Rueil-Malmaison (1989)
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    Lasers in medical science 4 (1989), S. 397-399 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Our Laser Platform reaches more than 9 years of surgical experience, using the CO2 and the Nd:YAG lasers in a multidisciplinary way. By the end of September 1988, 2609 surgical laser procedures have been performed. Bronchoscopic and GI endoscopic laser procedures are not included in this data. Since 3 years, the laser sessions of the annual French Surgical Association Congress are under our responsability. This paper relates the previous laser workshops programs and details the forthcoming workshop on Lasers in Proctology.
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    In comparison: 1.064 μm-1.318 μm Nd-YAG continuous wave lasers. In vitro and in vivo experiments for endoscopic tumour therapy in the gastrointestinal tract (1989)
    Springer
    Lasers in medical science 4 (1989), S. 25-31 
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    ISSN: 1435-604X
    Keywords: 1.318μm Nd-YAG laser ; Laser tissue effects ; New wavelength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract In in vitro and animal experiments the tissue effects of the 1.318μm Nd-YAG laser were compared to those of the standard 1.064μm Nd-YAG laser in order to evaluate the advantages of the new wavelength with a ten times higher absorption in water for gastroenterological tumour treatment. Under irradiation parameters related to clinical endoscopic practice, the laser of the wavelength 1.318μm needs for both vaporization and coagulation significantly less energy than the 1.064μm laser. Since vaporization at 1.318μm is always accompanied by a higher coagulation effect compared to 1.064μm the risk of late necrosis and resulting perforation appears to be increased.
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    A mathematical model for interstitial laser treatment of tumours using four fibres (1989)
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    Lasers in medical science 4 (1989), S. 41-53 
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    ISSN: 1435-604X
    Keywords: Mathematical model ; Laser surgery ; Optical fibres ; Tumours ; Thermal diffusion ; Multiple fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A mathematical model is employed to discuss the region treated by local hyperthermia, when the source of heat is a laser whose energy is directed into the treatment region through four optical fibres ending at the corners of a square. If treatment is over a period that is substantially longer than the time for the temperature distribution to reach equilibrium, a steady state model using four point sources can be employed to obtain a general idea of the temperatures reached and the region treated for different power levels and sizes of square. For shorter times, and for more accurate estimation of the regions treated, numerical calculation on a computer is essential. The details of the calculation depend on individual cases, but we demonstrate here that such computations are possible, and present a series of typical results. A comparison is made with the results of a series of experiments on canine liver, showing that it is possible to obtain good qualitative and numerical agreement.
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    A mathematical analysis of the results of experiments on rats' livers by local laser hyperthermia (1989)
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    Lasers in medical science 4 (1989), S. 55-64 
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    ISSN: 1435-604X
    Keywords: Laser hyperthermia ; Mathematical model ; Tumours ; Optical coefficients ; Optical fibres ; Thermal diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A time dependent mathematical model of optical energy transfer and heat conduction in tissue with strong anisotropic scattering is used to analyse the results of experiments (1) in which the livers of rats were treated by local laser hyperthermia. Good qualitative agreement to the temperature distribution is possible, but satisfactory quantitative agreement is only possible if allowance is made for temperature dependence of the optical and thermal parameters. Analysis of the volume of tissue killed by the treatment shows a marked departure from the rule used in conventional hyperthermia to determine the region treated; the reason for this is not clear, but a number of possibilities are suggested.
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    Editorial (1989)
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    Lasers in medical science 4 (1989), S. 1-2 
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    Topics: Medicine , Physics , Technology
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    URL: http://dx.doi.org/10.1007/BF02276662
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    Metamodel: A key to intelligent CAD systems (1989)
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    Research in engineering design 1 (1989), S. 19-34 
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    ISSN: 1435-6066
    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 introduce the metamodel as a new modeling framework for design objects based on General Design Theory, a mathematical model of design. Using General Design Theory, the metamodel concept can serve three functions: (1) as a central modeling mechanism to integrate models, (2) as a mechanism for modeling physical phenomena, and (3) as a tool for describing evolving design objects. Modeling with multiple points of view is realized by representing physical phenomena that occur in the deisng object and by constructing models with knowledge of physics and design from the metamodel. We illustrate the first and second functions of metamodels with an example based on naive physics, and we illustrate the third function of the metamodel through design experiments. Finally, we present two systems to illustrate how the metamodel mechanism can be implemented.
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    A framework for design problem-solving (1989)
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    Research in engineering design 1 (1989), S. 75-86 
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    ISSN: 1435-6066
    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 develop atask-structure for design problem-solving. The task-structure of a complex problemsolving activity such as design is a hierarchical organization of subtasks. For each task in the task-structure, we can then proceed to investigate whatmethods may be available, and what knowledge and inference requirements each of these methods have. Some of the methods may be domain-specific, some of them more generic in character, some may involve traditional computational techniques, and some others may involve searching in a problem space for solutions to the task. However, this systematic process of identifying tasks, methods, and subtasks will help us to see how design as a general problem is solved not by one method or technique but by an opportunistic exploitation of whatever methods are available (i.e., theknowledge required for using a method is available) to help accomplish a subtask. Thus, in principle, very different methods and knowledge can be brought into play in as flexible a way as applicable. For design problem-solving, we provide such an analysis for a family of design methods that we callpropose-verify-critique-modify methods. We end with remarks about how these methods can be flexibly integrated in a control structure that matches the subtasks with methods for which knowledge is available.
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    Announcements (1989)
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    Research in engineering design 1 (1989), S. 145-146 
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    ISSN: 1435-6066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
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    Kinetic model of a DC oxygen glow discharge (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 189-206 
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    ISSN: 1572-8986
    Keywords: Glow discharge ; singlet oxygen ; negative ion ; oxygen atom ; kinetic model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A simple kinetic model predicting the concentration of oxygen atoms, metastable singlet molecules O2(a 1Δ) and negative ions O — in the positive column of a DC glow discharge is developed. The calculated O and O2(a 1Δ) concentrations are compared to previously reported measurements for pressuresp=0.2–2 Torr and discharge currentsI=10–80 mA. The electron density calculated from the continuity equationj=n e e v d agrees well with experiment. The rate coefficients for electron impact processes used in the balance equations of O, O2(a 1Δ), and O− were taken from the literature as a function of the reduced electric fieldE/N forE/N=40–80 Td. A reasonable agreement is obtained between the model and the experiment with a set of 10 reactions for the production and destruction of the above-mentioned species
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    Gas-phase reactions in plasmas of SF6 with O2: Reactions of F with SOF2 and SO2 and reactions of O with SOF2 (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 409-420 
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    ISSN: 1572-8986
    Keywords: Gas flow reactor ; plasma chemistry of SF6/O2 ; rate coefficients ; experimental
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The plasma chemistry of SF6/O2 mixtures is particularly complicated because of the large number of possible reactions. Over a wide range of conditions, products including SF4, SOF4, SOF2, and SO2F2 can be formed but thre is considerable uncertainty about the major reactions which contribute to the formation of these species. In this work reactions of oxygen atoms with SOF2 and fluorine atoms with SOF2 and SO2 have been studied in order to determine the principal sources of SO2F2 in these plasmas. Reactions were studied at 295 K in a gas flow reactor sampled by a mass spectrometer. No reaction could be detected between oxygen atoms and SOF2, which for the conditions employed, means that the upper limit for the reaction rate coefficient is 1×10−14 cm3 sec−1. The reaction of fluorine atoms with SOF2 was studied with the helium bath gas number density ranging from 3.1×1016 to 2.0×1017 cm−3. Within this range the rate coefficient increased with increasing [He] from (4.1 to 10.8)×10−14 cm3 sec−1. SO2 was found to react with fluorine atoms with a rate coefficient which appeared to be independent of the helium bath gas number density over the range given above. The possibility that this reaction occurred entirely on the walls of the reactor is discussed.
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    Drag on a metallic or nonmetallic particle exposed to a rarefied plasma flow (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 387-408 
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    ISSN: 1572-8986
    Keywords: Particle drag force ; free-molecule flow regime ; pressure effect ; two-temperature plasma ; analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Drag force on a metallic or nonmetallic spherical particle exposed to a plasma flow is studied for the extreme case of a free-molecule regime. Analytical expressions are derived for the drag components due to, respectively, atoms, ions, and electrons and for the total drag on the whole sphere due to all the gas species. It has been shown that the drag is proportional to the square of the particle radius or the drag coefficient is independent of the particle radius. At low gas temperatures with a negligible degree of ionization, the drag is caused mainly by atoms and could be predicted by using the well-known drag expression given in ordinary-temperature rarefied gas dynamics. On the other hand, the drag is caused mainly by ions at high plasma temperatures with a great degree of ionization. The contribution of electrons to the total drag is always negligible. Ignoring gas ionization at high plasma temperatures would overestimate the particle drag. There is a little difference between metallic and nonmetallic spheres in their total drag forces, with a slightly higher value for a metallic sphere at high plasma temperatures, but usually such a small difference could be neglected in engineering calculations. The drag increases rapidly with increasing gas pressure or oncoming speed ratio. For a two-temperature plasma, the drag increases at low electron temperatures but decreases at high electron temperatures with the increase in the electron/heavy-particle temperature ratio.
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    Aspects of the chemistry of SF6/O2 plasmas (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 483-496 
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    ISSN: 1572-8986
    Keywords: Low-pressure plasma ; rate coefficients ; analytical/experimental
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The production ofSOF 4 initiated by the reaction of F atoms withSOF 2 has been studied in a gas-flow reactor at 295 K for helium bath gas number densities in the range (3.0–27.0)×1016 cm−3. The effect of O atoms on the formation ofSOF 4 has been analyzed in terms of the competing reactionsSOF 3+F→SOF4 andSOF 3+O→SO 2 F 2+F. This analysis leads to the conclusion that the rate coefficients for these two processes are equal within an uncertainty of about 50%. Furthermore, both experiment and calculations indicate that the rate coefficient for reactions between F atoms andSOF 3 is close to its high-pressure limit under the conditions employed. The experiments set a lower limit on this rate coefficient of 5×10−11 cm3 s−1, while calculations based on unimolecular rate theory suggest that it may be greater than 1×10−10 cm3 s−1. These results make it clear that the two reactions shown above cannot explain the relative abundances ofSOF 4 andSO 2 F 2 which are observed inSF 6/O 2 plasmas. This suggests thatSF 2 is a major precursor in the sequence of reactions following the dissociation ofSF 6.
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    Rf plasma processing of silica (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 371-386 
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    ISSN: 1572-8986
    Keywords: rf plasma ; silica ; thermal decomposition and reduction ; modeling and experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The processing of silica in an rf plasma was studied with a new experimental system, the process being carried out entirely in the vapor phase. SiO and Si were obtained by either thermal decomposition of SiO2 or reduction by H2. No other reducing material (which, like C, may become a contaminant) was used. The products were collected along the reactor length and analyzed afterward. Temperatures in the reaction zone were measured spectroscopically. The high reaction rates occurring in the gas phase did compensate for the low residence times. A diffusional model for the buildup of solid reaction products is discussed. Vapor phase plasma reduction of silica with hydrogen proved to be more effective than thermal decomposition and nuch more effective than heterogeneous processing. The efficiency evaluation was made on the laboratory-scale level.
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    A novel approach for introducing particulate matter into thermal plasmas: The triple-cathode arc (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 465-481 
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    ISSN: 1572-8986
    Keywords: High-intensity arcs ; powder processing ; anode heat transfer ; spectroscopic temperature measurement ; thermal plasmas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A coalesced high-intensity dc discharge is maintained between three cathodes and a single anode, stabilized by using resistors on each cathode leg. Jets of plasma gas are produced from either the cathode area or the anode area of the device. Cathode jets are generated by the self-induced pumping at the cathode tips and augmented by central gas injection. Arc voltage-current characteristics show classical convection-stabilized arc behavior. Anode heat transfer rates may be substantially increased by central gas injection toward the anode. Temperature fields in the coalesced, axially symmetric portion of the arc are determined spectrometrically and compared to those of a classical single-cathode free-burning arc.
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    Thermal plasma composition in the presence of easily and noneasily ionized components (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 445-463 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; equilibrium composition ; metal halide discharge ; easily and noneasily ionized components
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The influence of easily and noneasily ionized components on equilibrium particle density ratios in thermal plasmas has been investigated. Particular emphasis is given to the modeling of metal halide discharges with iodine as a halide. The calculations were done for “standard” air with lithium or iodine, “standard” argon with aluminum, and with a mixture of aluminum and iodine. The system setup is in agreement with spectroscopic results for an open-chamber gas-stabilized d.c. arc, with a pressure of 1×105 Pa and temperatures corresponding to the radial distribution of temperature for this type of discharge. It is shown that the behavior of the plasma core is dominated by the easily ionized component (Li or Al) while the periphery is characterized by the noneasily ionized component (iodine).
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    Production of XeO* in a CW microwave discharge (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 497-511 
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    ISSN: 1572-8986
    Keywords: Microwave discharge ; XeO ; emission spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A low-power CW microwave discharge at 2.45 GHz was used to produce XeO* excimer molecules. It was found that a total gas pressure between 5 and 20 Torr, absorbed power of about 20–100 W, and an oxygen-to-xenon ratio of 1∶100 maximized the XeO(1S−1D) green emission at 5200 to 5600 Å. The XeO* emission appeared in the cooler parts of the discharge near the containment tube walls and in the electric field nodes of the TM012 resonant mode.
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    A review of the EPRI-sponsored workshop on research opportunities for Plasma Processing (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 3S 
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
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    Important announcement (1989)
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    Plasma chemistry and plasma processing 9 (1989), S. 1-1 
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    ISSN: 1572-8986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
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    URL: http://dx.doi.org/10.1007/BF01015822
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    On the effect of low-energy ion bombardment on polystyrene and polymethylmethacrylate etch rates in rf plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 3-12 
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    ISSN: 1572-8986
    Keywords: Etching ; polystyrene ; polymethylmethacrylate ; ion bombardment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The effect of low-energy ion bombardment on CD4/O2 and CF3X (X=F, Cl, Br) plasma etching has been assessed by applying controlled rf bias voltages on polystyrene (PS) and polymethylmethacrylate (PMMA) samples. In both cases ion bombardment has been found to have a “chemical” effect. In the case of CF4/O2 discharges, ion bombardment has been found to change the relative etching efficiency of different mixtures. In the case of CF3X plasmas, ion bombardment has been found to alter PMMA and PS etch rates in a different way. In particular, the ratios between CF4 and CF3X (X=Cl, Br) etch rates of PS have been found to decrease with increasing bias voltage. This effect has been tentatively attributed to an ion bombardment-induced enhancement of the reaction between the aromatic ring and halogen molecules formed in CF3Cl and CF3Br discharges.
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    Characterization of silicon nitride particles synthesized in an atmospheric-pressure convection-stabilized arc (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 73-93 
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    ISSN: 1572-8986
    Keywords: Thermal plasma ; Si3N4 synthesis ; product morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Silicon nitride powders were synthesized in an atmospheric-pressure convection-stabilized arc using silicon and ammonia as reactants. The morphology and particle size distributions of the silicon nitride particles were characterized by SEM, TEM, and electron diffraction analyses. The silicon nitride particles collected in the plasma reactor were formed by either gas-condensed phase reactions or chemical vapor reactions. The morphologies of the particles formed by gas-condensed phase reactions consisted of β-Si3N4 prisms, α-Si3N4 matte, α-Si3N4 needles, and spaghetti-like whiskers. For the homogeneously nucleated particles, the morphologies included dendrites, needles, platelets, and amorphous particles. Most of the particles formed were aggregates with particle size distributions ranging from 500 to 1500 Å depending on the location of injection of the reactants.
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    Cathode erosion in inert gases: The importance of electrode contamination (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 121-132 
    Details
    ISSN: 1572-8986
    Keywords: Electrode erosion ; plasma torches ; magnetic rotation ; contamination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Experimental results are presented for electrode erosion on copper electrodes in magnetically rotated arcs in argon and helium. Measurements were also made of the arc voltage and velocity. The effects due to the contamination of the electrode surface by either a native contaminant layer (copper oxide and carbon traces) or the continuous injection of very small amounts of various diatomic gases (nitrogen, oxygen, chlorine, and carbon monoxide) into the inert plasma gases were determined. The erosion rates for pure argon were significantly higher than those for pure helium (13.5 μg/C for argon and 1 μg/C for helium) and with both gases, very high arc velocities were measured initially (〉60 m/s for argon and 〉160 m/s for helium) when a natural contaminant layer was still present on the cathode. The removal of this layer resulted in lower velocities (2m/s for argon and 20m/s for helium) and higher erosion rates. The removal of the layer was much faster with argon, due possibly to higher electrode surface current densities for argon arcs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015830
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    Temporally resolved laser diagnostic measurements of atomic hydrogen concentrations in RF plasma discharges (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 157-164 
    Details
    ISSN: 1572-8986
    Keywords: Two-photon laser-induced fluorescence (TALIF) ; laser diagnostic ; RF plasma discharge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Ground-state atomic hydrogen produced in radio-frequency plasma discharges (20 KHz-5 MHz) has been detectedin situ using two-photon absorption laser-induced fluorescence (TALIF). Atomic ground-state concentration measurements have demonstrated excellent spatial resolution in the interelectrode gap of a planar discharge configuration with 10 nsec temporal resolution at all phases of the RF driving voltage waveform. Concentrations were measured in gas mixtures of helium and hydrogen down to 2×1013 H atoms/cm3.
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    URL: http://dx.doi.org/10.1007/BF01054278
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    Deposition of organosilicone plasma polymer onto cellulose networks (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 225-234 
    Details
    ISSN: 1572-8986
    Keywords: Coatings ; electron microscopy ; fibers ; fibrils ; paper sheets ; plasma ; polymers ; polymerization ; organosilicones ; pores ; surface properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The deposition of organosilicone plasma polymers on the surface of paper has been examined by scanning and transmission electron microscopy. Plasma polymer was deposited on fibers and fibrils near the surface of the sheet, the coating thickness being highest in those regions which were directly exposed to the plasma. As the coating thickness was increased, pores in the paper surface closed.
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    URL: http://dx.doi.org/10.1007/BF01054283
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    Probe measurements in argon plasma jets operated in ambient argon (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 329-341 
    Details
    ISSN: 1572-8986
    Keywords: Plasma jets, argon atmosphere ; temperatures and velocities ; probe measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Measurements of local enthalpies and velocities have been performed in plasma jets generated by a DC plasma spray torch, using an enthalpy probe. The torch has been operated in an argon confined atmosphere at different currents and argon flow rates.(1) The validity of the measured enthalpy and velocity profiles has been checked by performing energy flux and mass flux balances, which show reasonable agreement between the input quantities, measured independently, and those obtained by integrating over the experimental profiles. The data are compared with those obtained by operating the same torch in ambient air. The results show that temperatures and velocities measured in pure argon are substantially higher than those in air, and consequently, the jets in argon appear wider and substantially longer.
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    URL: http://dx.doi.org/10.1007/BF01054288
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    Homogeneous nucleation of particles from the vapor phase in thermal plasma synthesis (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 355-369 
    Details
    ISSN: 1572-8986
    Keywords: Plasma synthesis ; homogeneous nucleation ; ultrafine powders
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Particle nucleation and growth are simulated for iron vapor in a thermal plasma reactor with an assumed one-dimensional flow field and decoupled chemistry and aerosol dynamics. Including both evaporation and coagulation terms in the set of cluster-balance rate equations, a sharply defined homogeneous nucleation event is calculated. Following nucleation the vapor phase is rapidly depleted by condensation, and thereafter particle growth occurs purely by Browntan coagulation. The size and number of nucleated particles are found to be affected strongly by the cooling rate and by the initial monomer concentration. An explanation is presented in terms of the response time of the aerosol to changing thermodynamic conditions.
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    URL: http://dx.doi.org/10.1007/BF01083672
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    Nonequilibrium effects in thermal plasma chemistry (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 435-443 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; nonequilibrium ; finite rates ; dissociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Numerical calculations have been performed to assess the potential significance of nonequilibrium effects on chemical reactivity in thermal plasmas The calculations consider situations in which the electron temperature and/or the electron density are elevated above their equilibrium values corresponding to the local gas temperature. Such nonequilibrium may occur in the plasma torch itself or could be purposefully imposed by a controlled hybrid discharge in a downstream reactor region so as to augment reactivity over a longer residence time. The calculations account for finite ionization/recombination rates of atomic and molecular species, electron-impact dissociation, dissociative recombination, dissociative attachment, and predissociation effects, as well as thermal reactions between neutral chemical species. As an example of the possible nonequilibrium enhancement of molecular decomposition, initial consideration has focused on the dissociation rates of diatomic species where heavy particle reaction rates and cross sections can be reasonably estimated. The results show that for O2 or H2 in argon at moderate temperatures, electron-temperature elevation can give rise to a notable enhancement of the dissociation rate, in comparison with the equilibrium case. Depending on the situation, it is found that either relatively energetic electron-impact dissociation or dissociative attachment (for O2) can dominate the enhanced dissociation rate—which can be more than a factor of 2 greater than in the absence of a discharge. Similar effects would be expected for the decomposition of more complicated molecules.
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    URL: http://dx.doi.org/10.1007/BF01023912
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    Plasma-assisted etching of aluminum in CCl4−Cl2 mixtures (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 513-525 
    Details
    ISSN: 1572-8986
    Keywords: Aluminum etching ; clean-aluminum etching kinetics ; plasma etching ; CCl4−Cl2 discharges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The etching of aluminum has been studied in a diode reactor fed with CCl4−Cl2 mixtures. The overall reaction has been found to be influenced by the contemporaneous deposition of low-volatile etch products and/or a chlorocarbon polymer film originating from the polymerization of CClx species. A simple approach is described which allows the chemical contribution to the etch process to be distinguished from the physical one of through-film diffusion. The etching of a “clean” Al surface is shown to be controlled by chlorine chemisorption at low temperature.
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    URL: http://dx.doi.org/10.1007/BF01023917
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    Microwave heating systems for atmospheric pressure: Nonequilibrium plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 55S 
    Details
    ISSN: 1572-8986
    Keywords: Nonequilibrium plasma ; microwave discharge ; atmospheric pressure ; large volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Nonequilibrium plasma-chemical processing is attracting increasing interest because of the possibility of creating mixtures of active species that would not be available in thermal equilibrium. For significant throughput of reactants it would be advantageous to create nonequilibrium plasmas in large volumes of atmospheric-pressure mixtures of gases. Techniques for accomplishing this are very limited at present. Here we describe a novel microwave approach to creating nonequilibrium plasmas in large volumes of atmospheric-pressure gases using pulses of microwave radiation with very high peak power that are focused by quasi-optical techniques at one or more points in the interior of the reaction chamber. A new type of microwave source, the Plasma Electron Microwave Source (PEMS), is able to produce the required power levels by storing cw microwave power in a mirror-confined, relativistic-electron plasma and periodically transforming a fraction of that stored energy into intense microwave pulses. This approach avoids many of the limitations inherent in resonant cavity approaches and is expected to permit ultrahigh purity discharges to be produced.
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    URL: http://dx.doi.org/10.1007/BF01015873
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    Some characteristics of transferred-Arc plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 65S 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arcs ; plasma radiation ; plasma heat transfer ; plasma columns ; plasma stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Although the theoretical foundations of the characteristics of transferred arcs were established more than three decades ago, the design of reator systems based on this method of plasma are generation is still in an early stage of development. Although deceptively simple in concept, attempts to use transferred arcs im practical applications at scales of arc length and power somewhat larger than those previously studied in the laboratory soon revealed that considerably more information was required on the arc's unique properties before a sound reactor design could be carried out. This was principally due to the much higher temperature levels (up to 20,000 K) with consequent much higher radiative power achieved in this type of arc, as well as the fluid mechanical effects of the high-velocity plasma gas flowing in the latter. These, in turn, had profound effects on the various modes of heat transfer occurring in the system, on the stability of the arc, on the injection of the material to be treated, and on the overall efficiency of energy utilization in the whole system. The objective of this paper is to summarize the experimental evidence concerning transforred arc characteristics which have been obtained by the author and his colleageus during recent years.
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    URL: http://dx.doi.org/10.1007/BF01015874
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    Particle behavior in thermal plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 167S 
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    ISSN: 1572-8986
    Keywords: Thermal plasmas ; heat, mass, and momentum transfer ; material processing ; overview
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this overview, effects exerted on the motion and on heat and mass transfer of particulates injected into a thermal plasma are discussed, including an assessment of their relative importance in the context of thermal plasma processing of materials. Results of computer experiments are shown for particle sizes ranging from 5–50 μm, and for alumina and tungsten as sample materials. The results indicate that (i) the correction terms required for the viscous drag and the convective heat transfer due to strongly varying properties are the most important factors; (ii) noncontinuum effects are important for particle sizes 〈10 μm at atmospheric pressure, and these effects will be enhanced for smaller particles and/or reduced pressures; (iii) the Basset history term is negligible, unless relatively large and light particles are considered over long processing distances; (iv) thermophoresis is not crucial for the injection of particles into thermal plasmas; (v) turbulent dispersion becomes important for particle 〈10 μm in diameter; and (vi) vaporization describes a different particle heating history than that of the evaporation process which, however, is not a critical control mechanism for interphase mass transfer of particles injected into thermal plasmas.
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    URL: http://dx.doi.org/10.1007/BF01015878
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    Methane polymerization with a hollow cathode: Influence of the cathode metal (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 527-543 
    Details
    ISSN: 1572-8986
    Keywords: Plasma polymer ; hollow cathode ; CH• radical ; molecular spectroscopy ; platinum catalyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Methane, mixed with argon, has been polymerized by means of a hollow-cathode discharge system. Two types of cathodes were studied; one was made of a solid solution of 81% tungsten and 19% platinum, while the other was of pure tungsten. Under identical operating conditions, a higher polymer yield was found in the case of the platinum cathode (90% against 70% for tungsten). The work function of the solid solution was estimated to be 6.3 eV, compared with 4.4 eV for tungsten. In terms of the data available, the thermionic current, which is the main source of energetic electrons, is about one order of magnitude lower for the solid solution cathode when compared with the tungsten cathode thermionic current. However, the polymer yield observed is higher in the former case. The concentration of the CH• species in the hollow cathode was found to differ greatly for the cathodes tested and was about 5 times higher in the case of tungsten-platinum cathodes. Since no excited platinum vapor could be detected in the gas phase, the increase in CH• concentration was attributed to a catalytic effect of the cathode inside surface. An evaluation of the plasma polymer deposition rate yields 70 nm·s−1 for the platinum-tungsten type hollow cathode and 42 nm·s−1 for the tungsten one. In both cases, the deposition rate is much higher than those obtained from the most widely used methods for plasma polymer deposition (0.10–1.0 nm·s−1) implying methane-argon mixtures, and is comparable to the results obtained with a new type of plasma polymer deposition reactor described in the literature.
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    URL: http://dx.doi.org/10.1007/BF01023918
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    Plasma arc process systems, reactors, and applications (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 85S 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasma ; plasma reactors ; waste treatment ; metals recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Thermal plasma arc systems are being applied to a wide variety of high-temperature applications. The use of electricity is proving to be a cost-effective alternative for the treatment of industrial wastes, recycling of scrap, upgrading of existing metallurgical processes, and new methods for the production of materials. Thermal plasma arc reactors are classified according to; (1) the mode of arc attachment, as nontransferred and transferred: and (2) the site for energy and/or mass transfer, as dispersed phase or condensed phase (bulk, film and packed bed). Unique features in the design of plasma reactor systems and applications in waste treatment and metals production are discussed.
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    URL: http://dx.doi.org/10.1007/BF01015875
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    In memoriam (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 433-433 
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    ISSN: 1572-8986
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01083677
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    Synthesis of ammonia in high-frequency discharges. II. Synthesis of ammonia in a microwave discharge under various conditions (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 421-432 
    Details
    ISSN: 1572-8986
    Keywords: Ammonia synthesis ; microwave discharge ; NHx radicals ; nitrogen-hydrogen reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The synthesis of ammonia from nitrogen-hydrogen plasma prepared using microwave discharge was studied by changing some experimental conditions, such as pressure (260–2600 Pa), power input (30–280 W), and nitrogen-hydrogen mixing ratio [H2/(N2+H2)=0−1.0]. The ammonia yield increased with decreasing pressure and saturated at lower pressures. When the power input and the nitrogen-hydrogen mixing ratio were changed, the maximum yield of ammonia was obtained at the optimum experimental conditions (power input ≈150W; H2/(N2+H2)≈0.75). Amounts of NH, H, and H2 in the plasma also changed by changing the experimental conditions. From the changes in ammonia yield and amounts of NH, H, and H2 by changing the experimental conditions, it is suggested that ammonia molecules are formed by the reaction of NH radicals not only with hydrogen atoms but also with hydrogen molecules. Otherwise, the formation and the decomposition of ammonia would occur simultaneously.
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    URL: http://dx.doi.org/10.1007/BF01083676
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    Two-dimensional electromagnetic field effects in induction plasma modelling (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 25-44 
    Details
    ISSN: 1572-8986
    Keywords: Modelling ; induction plasmas ; flow and temperature field ; two-dimensional electromagnetic fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Based on the electromagnetic vector potential representation, a two-dimensional, axisymmetric model is proposed for the calculation of the electromageetic fields in an inductively coupled, radiofrequency (r.f.) plasma. A comparative analysis made between the flow, temperature, and electromagnetic fields obtained using this model and those given by our earlier one-dimensional electromagnetic fields model show relatively little difference between the temperature fields predicted by the two models. Significant differences are observed, however, between the corresponding flow and electromagnetic fields. The new model offers an effective means of accounting for variations in the coil geometry on the flow and temperature fields in the discharge and for achieving a better representation of the electromagnetic fields under higher frequency conditions (f〉10 MHz).
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    URL: http://dx.doi.org/10.1007/BF01015825
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    Initial stages of soot formation in thermal pyrolysis of acetylene. I. Mechanism for homogeneous pyrolysis of acetylene (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 95-104 
    Details
    ISSN: 1572-8986
    Keywords: Acetylene ; carbene ; mechanism ; pyrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A probable mechanism for the homogeneous pyrolysis of acetylene, using carbene reactions, is considered. Analysis of the energetics for the probable mechanism of the initiation reactions shows the rearrangement C2H2→∶CCH2 to be the most probable. Using the energetic barriers for simple carbene reactions and formation enthalpies for more complicated carbenes, we evaluated the activation energies for the reactions mechanism. The vibrational excitation of the products of carbene reactions is taken into account. Calculations of the acetylene conversion kinetics and yields of the main gas-phase pyrolysis products, based on the carbene molecular mechanism, show significantly better agreement with available experimental data as compared to those based on traditional radical mechanisms. The calculated time for the appearance of aromatic products is close to the measured induction times for the appearance of soot particles.
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    URL: http://dx.doi.org/10.1007/BF01015828
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    Initial stages of soot formation in thermal pyrolysis of acetylene. II. A model for the incipience and growth of soot particles (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 105-120 
    Details
    ISSN: 1572-8986
    Keywords: Soot particles ; nucleation ; surface growth ; coagulation ; size distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model is developed which describes simultaneously occurring processes of the initial hydrocarbon pyrolysis, nucleation, surface growth, and coagulation of soot particles. The model permits one to find the size distribution of the “primary” soot particles up to size 30–40 nm using a relatively small set of equations. The computed time dependence of soot particle concentration agrees satisfactorily with available experimental data. The existence of two limiting stages of the soot formation is revealed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015829
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    Calculation of transport coefficients of air plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 133-154 
    Details
    ISSN: 1572-8986
    Keywords: Thermodynamic and transport properties ; calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper is devoted to results of calculation of the main transport coefficients of air plasmas: electrical and thermal conductivities and viscosity. These calculations are performed for pressures between 1 and 200 atm and for temperatures varying from 1000 to 30,000 K. The computational methods proposed by Devoto from the classical formalism described by Hirchfelder et al. are used. Collision integrals for interactions between charged particles are calculated using the formalism of Mason et al. to account for the fact that, in most of the situations considered here, the number of charged particles in the Debye sphere is weak.
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    URL: http://dx.doi.org/10.1007/BF01015831
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    Kinetic study of low-pressure H2 multipole discharge (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 165-188 
    Details
    ISSN: 1572-8986
    Keywords: Low-pressure multipole discharge ; kinetic equilibrium among species ; electron energy distribution function ; Balmer line profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper is devoted to the study of kinetic equilibrium among electrons, H2 molecules, H atoms, and positive H+, H 2 + , and H 3 + ions in a multipole discharge working under low-pressure (1- to 15-m Torr) and moderated current conditions. In such a discharge used either as a H+ or a H− ion source or for plasma-surface interactions, the dependence of the densities of these species versus experimental parameters is of a great interest. In the present situation, the electron energy distribution function (e.e.d.f.) is largely nonmaxwellian. The kinetic model that determines the densities of the plasma species is self-consistently coupled to the e.e.d.f. calculated through the use of the Boltzmann equation. The influence of the main processes, volume ones, and those involving plasma walls is emphasized. An attempt is made to use the profiles of Balmer lines obtained experimentally in order to determine absolute concentrations of H atoms and H 2 + ions. Results derived from the experiment are compared to results of the model. Such an analysis of Balmer line shapes appears to be an interesting way to determine, by anin situ nonintrusive method, the absolute concentration of H atoms.
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    URL: http://dx.doi.org/10.1007/BF01054279
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    Heterogeneous effects in the process of ozone synthesis in electrical discharges (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 235-255 
    Details
    ISSN: 1572-8986
    Keywords: Ozone synthesis ; heterogeneous catalysis ; silica ; semicorona discharges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Catalytic effects of solid surfaces in the synthesis of ozone have been examined under semicorona discharges conditions. It was found out that in the presence of a granular dielectric (silica) in the discharge gap, the ozone formation was accelerated and higher ozone concentrations were obtained. The mechanism of catalytic effects of silica is discussed.
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    URL: http://dx.doi.org/10.1007/BF01054284
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    Silicon nitride synthesis in an atmospheric pressure convection—Stabilized arc (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 277-289 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; synthesis of Si3N4 ; experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Submicron α-, β-, and amorphous-phase silicon nitride particles have been synthesized in an experimental plasma reactor, using metallic silicon and ammonia as reactants. Injection of ammonia at different locations of the reactor results in different yields. A maximum yield of 85 wt% has been achieved by injecting NH3 at both downstream and upstream locations of the reactor. The powders synthesized in this way contained approximately 60 wt% silicon nitride in crystal form with equal amounts of α and β phases. The remainder consisted of the amorphous phase. The average size of the particles ranged from 50 to 90 nm, with a standard deviation of 1.47–1.87 depending on the location of ammonia injection. Seeding with 1 and 10 wt% of preexisting silicon nitride particles for fostering heterogeneous nucleation did not improve the yield, but it changed the particle size distribution.
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    URL: http://dx.doi.org/10.1007/BF01054286
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