ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Hall-effect characterization in semiconductor heterostructure junctions using polarized laser signal : The 40th annual conference on magnetism and magnetic materials (1996)

How, Hoton ; Fang, Ta-Ming ; Lu, Feng ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 79 (1996), S. 4759-4761

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: We describe a new technique which exploits the ac Hall effect in the characterization of layered semiconductor structures. The method employs laser signals in the presence of a dc magnetic bias field. Upon incidence the polarization of the optical signal is rotated via a Lorentz force due to the ac Hall effect. As such, the reflected waves carry information on the Hall mobility of the charge carriers. The calculations show that ac Hall reflection warrants sufficient intensity to be measured. Our theory is complete in the sense that depth profiling has been explicitly incorporated in the formulation. © 1996 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.361663

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2

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Strong room-temperature infrared emission from Er-implanted porous Si (1995)

Namavar, Fereydoon ; Lu, Feng ; Perry, Clive H. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 77 (1995), S. 4813-4815

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: This communication demonstrates a strong, room-temperature (RT), infrared (IR) (1.54 μm) emission from Er-implanted red-emitting (peaked at 1.9 eV) porous silicon (Er:PSi). Erbium was implanted into porous Si, bulk Si, and quartz with a dose of 1015/cm2 at 190 keV and annealed for 30 minutes in N2 at temperatures ranging from 500 °C to 900 °C under identical conditions. No RT IR emission was observed from Er implanted quartz and silicon after annealing at 650 °C (although after annealing at 900 °C very weak emission was observed from quartz at 9 K). The highest RT emission intensity at 1.54 μm was from Er:PSi with a peak concentration of 1.5×1020/cm3 and annealed at 650 °C. Even the luminescence intensity from Er:PSi annealed at 500 °C was 26 times higher than that observed from Er-implanted quartz at 400 keV and annealed at 900 °C. A reduction in photoluminescence (PL) intensity of about a factor of two from Er:PSi over the 9 to 300 K temperature range was observed which is consistent with Er in wide band gap materials. © 1995 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.359403

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3

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Photoluminescence spectra from porous silicon (111) microstructures: Temperature and magnetic-field effects (1992)

Perry, Clive H. ; Lu, Feng ; Namavar, Fereydoon ; [et al.]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 60 (1992), S. 3117-3119

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ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: Visible and near-infrared (IR) photoluminescence emission spectra (0.9–3.0 eV) from p-type porous Si(111) microstructures are reported as a function of temperature and magnetic field. The visible peak located at 1.84 eV at 4 K shifted to ∼1.56 eV at 575 K where it disappeared; the intensity reached a maximum value at ∼150 K. The photoluminescence spectrum showed no measurable shift in the peak position with magnetic field from 0 to 15 T. Strong IR intrinsic band-to-band emission above and below the bulk silicon band gap at ∼1.09 eV at 300 K was observed. This luminescence was found to be enhanced by two orders of magnitude or more over the IR spectrum from an unanodized wafer.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.106770

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4

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Massive dolomitization of a late Miocene carbonate platform: a case of mixed evaporative brines with meteoric water, Nijar, Spain (1998)

Lu, Feng H. ; Meyers, William J.

Oxford UK : Blackwell Science Ltd, UK

Sedimentology 45 (1998), S. 0

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ISSN: 1365-3091

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences

Notes: Late Miocene platform carbonates from Nijar, Spain, have been extensively dolomitized. Limestones are present in the most landward parts of the platform, in stratigraphically lower units and topographically highest outcrops, suggesting that dolomitizing fluids were derived from the adjacent Nijar Basin. The dolomite crystals range from 〈10 to ≈100 μm existing as both replacements and cements. Na, Cl and SO4 concentrations in the dolomites range from 200 to 1700 p.p.m., 250–650 p.p.m., and 600–7000 p.p.m., respectively, comparable with other Tertiary and modern brine dolomite values, and also overlapping values from mixing-zone dolomites. Sr concentrations range between 50 and 300 p.p.m., and the molar Sr/Ca ratios of dolomitizing fluids are estimated to range between 7× seawater brine to freshwater ratios. The δ18O and δ13C of the dolomites range from −1·0 to +4·2‰ PDB, and −4·0 to +2·0‰ PDB, respectively. 87Sr/86Sr values (0·70899–0·70928) of the dolomites range from late Miocene seawater to values greater than modern seawater.Mixtures of freshwater with seawater and evaporative brines probably precipitated the Nijar dolomites. Modelled covariations of molar Sr/Ca vs. δ18O and Na/Ca vs. δ18O from these mixtures are consistent with those of the proposed Nijar dolomitizing fluids. Complete or partial dolomite recrystallization is ruled out by well preserved CL zoning, nonstoichiometry and quantitative water–rock interaction modelling of covariations of Na vs. Sr and δ18O vs. δ13C. The possibility of multiple dolomitization events induced by evaporative brines, seawater and freshwater, respectively, is consistent with mineral-mineral mixing modelling.The basin-derived dolomitizing brines probably mixed with freshwater in the Nijar Basin or mixed with fresh groundwater in the platform, and were genetically related either to deposition of the Yesares gypsum or the Feos gypsum. Dolomitization occurred during either the middle Messinian or the early upper Messinian. Nijar dolomitization models may be applicable to dolomitization of other late Miocene platform carbonates of the western Mediterranean. Moreover, the Nijar models may offer an analogue for more ancient evaporite-absent platform carbonates fringing evaporite basins.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3091.1998.0142e.x

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5

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Influence of Shot Peening on Fatigue Properties in Ultra-High Strength Steels (2005)

Gao, Yu Kui ; Wu, Xue Ren ; Lu, Feng ; [et al.]

s.l. ; Stafa-Zurich, Switzerland

Materials science forum Vol. 490-491 (July 2005), p. 448-453

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ISSN: 1662-9752

Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: The characteristics of compressive residual stress fields induced by shotpeening in 40CrNi2Si2MoVA, 16Co14Ni10Cr2Mo, 30CrMnSiNi2A and 0Cr13Ni8Mo2Al ultra-high strength steels, which are used widely in aeronauticalindustry were investigated, and the change of surface integrity including surfaceresidual stress, surface roughness as well as its effects on fatigue properties wereinvestigated. The results show that the fatigue limits of ultra-high strength steels canbe increased by shot peening because the surface integrity can be ameliorated by shot peening, and that for a given steel there is a appropriate peening intensity under which the fatigue property of this steel is optimum. Finally, a judgement for the optimization condition of shot peening process is proposed based on a theory of micro-meso processes of fatigue crack initiation and experimental results. The technique should be considered to be optimum, if the fatigue crack source of shot peened specimen has been moved to the internal matrix metal region beneath the hardened layer; and its apparent fatigue limit has been improved and got to a value, which is near to that predicted according to the concept of surface/internal fatigue limit

Type of Medium: Electronic Resource

URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/10/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.490-491.448.pdf

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6

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Structure and property changes in certain materials influenced by the external qi of qigong (1999)

Yan, Xin ; Lin, Hui ; Li, Hongmei ; [et al.]

Springer

Materials research innovations 2 (1999), S. 349-359

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ISSN: 1433-075X

Keywords: Key words Qigong ; Qi ; Material structure ; Material property ; Raman ; Water ; Protein ; Liposome ; Saline ; Glucose

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Temperature, time, pressure (or stress) are considered important factors in changing the Gibbs free energy and optimizing the structure and properties of materials during materials processing. The effects of some other variables, including the magnetic field, electrical field, electromagnetic and ultrasonic radiation, and chemical reactions have also been well characterized. These factors have been widely applied in materials processing, and their limitations have been discovered. Thus additional factors and innovative techniques are constantly being sought to overcome those limitations. This paper presents such an innovative technique called qigong. Three sets of materials-related experiments conducted by qigong doctor Yan and his collaborators are described in which for the first time the effects of qi on inanimate matter samples with no mechanical or electrical connection to the system are revealed on laboratory instruments. These experiments show that external qi of qigong produces significant structural changes in water and aqueous solutions, alters the phase behavior of dipalmitoyl phosphatidyl choline (DPPC) liposomes, and enables the growth of Fab protein crystals. These results demonstrate objective phenomena resulting from qigong and the potential of this ancient technology system, even in material processing. Important attributes of qi are summarized and the possible implications of these results from the materials perspective are discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s100190050113

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7

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Robot Pose Estimation in Unknown Environments by Matching 2D Range Scans (1997)

Lu, Feng ; Milios, Evangelos

Springer

Journal of intelligent and robotic systems 18 (1997), S. 249-275

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ISSN: 1573-0409

Keywords: robot pose estimation ; aligning scans ; rotation search ; reference scan

Source: Springer Online Journal Archives 1860-2000

Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract A mobile robot exploring an unknown environment has no absolute frame of reference for its position, other than features it detects through its sensors. Using distinguishable landmarks is one possible approach, but it requires solving the object recognition problem. In particular, when the robot uses two-dimensional laser range scans for localization, it is difficult to accurately detect and localize landmarks in the environment (such as corners and occlusions) from the range scans. In this paper, we develop two new iterative algorithms to register a range scan to a previous scan so as to compute relative robot positions in an unknown environment, that avoid the above problems. The first algorithm is based on matching data points with tangent directions in two scans and minimizing a distance function in order to solve the displacement between the scans. The second algorithm establishes correspondences between points in the two scans and then solves the point-to-point least-squares problem to compute the relative pose of the two scans. Our methods work in curved environments and can handle partial occlusions by rejecting outliers.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1007957421070

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8

Electronic Resource

A Conceptual Model for a Feature-Based Virtual Network (2000)

Zhou, Chenghu ; Lu, Feng ; Wan, Qing

Springer

Geoinformatica 4 (2000), S. 271-286

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ISSN: 1573-7624

Keywords: network ; data model ; feature ; object-oriented analysis ; virtual network

Source: Springer Online Journal Archives 1860-2000

Topics: Geography

Notes: Abstract Networks can be used as a model for the representation and analysis of the physical world. Traditional GIS data models need to be improved if GIS is to be more suitable for network modeling. This paper proposes a feature-based object-oriented data model for transportation networks. It breaks the limitations of the arc-node planar graph model in feature description and topology expression of complicated networks. The basic classes in the data model are explicitly defined. The difference and relationship between physical networks and virtual networks, and the topology representation in virtual networks are discussed. An object-oriented network analysis method is used to construct virtual networks over physical networks in order to make abstract networks more suitable for analysis, and includes a detailed example of a multi-modal traffic network.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009853309757

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