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Conservation laws for energy and momentum in curved spaces

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j.urnal of Zhej.ang University-Science A(Applied Physics & Engineering) 2007年第4期8卷 665-668页

作者： LóPEZ-BONILLA j. MORALES j. OVANDO G. Section of Postgraduate Studies and Research Superior School of Mechanical and Electrical EngineeringNational Polytechnic InstituteCP 07738Mexico Division of Basic Sciences and Engineering Autonomous Metropolitan UniversityCP 02200Mexico

In arbitrary Riemannian 4-spaces, continuity equations are constructed which could be interpreted as conservation laws for the energy and momentum of the gravitational field. Special attention is given to general relativity to obtain, of natural manner, the pseudotensors of Einstein, Landau-Lifshitz, Moeller, Goldberg and Stachel, and also the conservation equations of Komar, Trautman, DuPlessis and Moss.

关键词： Noether theorem Lagrangians in curved spaces Energy and momentum in Riemannian spaces Rund-Lovelock identities

Acoustic Measurements for Determination of the Materials Damping Using A Sound Source Localisation System

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Acta Metallurgica Sinica(English Letters) 2013年第2期26卷 113-121页

作者： j. Gken j. Swiostek H. Hurdelbrink U. Keil Faculty of Maritime Studies University of Applied Sciences Emden/Leer Bergmannstr. 36 26789 LeerGermany Stalomax TM Company of High-Precision Mechanics ul. Parkingowa 45 37450 Stalowa WolaPoland

Noise measurements are especially a problem when the obj.ct under investigation is largely dimensioned and can only be measured from the distance. To obtain information about the location of noise generation, a measurement technique which makes sound visible in order to introduce further specific technical measures is advantageous. The question is if the time dependence of the signal got from such a non touching and non destructive acoustic method has the potential to calculate the materials damping from. Using a small sound source localization system （Microflown^TM probe）, specimens of magnesium alloys with different grain sizes obtained by hydrostatic extrusion were investigated. It has been demonstrated that the fine grained microstructure led to a lower damping and its dependence on the strain was reduced. In this context, acoustic measurements by a sound source localisation system which makes materials characterization possible could be used as a quality tool to detect changes in highly stressed components. This approach allows to promote a selective substitution of conventional materials by more innovative ones. The offshore sector is considered to be a field of application： Wind turbines produce noise emission which stems mainly from turbulences at the tips of the rotor blades and vibrations of components inside the nacelle （e.9. gearbox, generator, ...）. If the vibration amplitudes are too high, microcracks of components can lead to failure over the long term. The monitoring of microstructural changes using a larger type of a sound source localisation system is considered as an innovative technical approach with respect to maintenance activities.

关键词： Magnesium Noise measurements MicroflownTM Damping

Inherent robust stability of driver support systems

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Science China(Technological Sciences) 1999年第4期42卷 437-448页

作者：王龙 j. Ackermann Robust Control Group Institute of Robotics and System Dynamics German Aerospace Research CenterD-82230 Wessling Germany)

Presented are the fact that the transfer function from the front steering angle to yaw rate is strictly positive real, irrespective of the uncertain mass and uncertain velocity, how to determine the positivity margin for this transfer function (some stabilization results are obtained), and how to check the positivity of a controller family. Furthermore,by exploiting the intrinsic structure of system equations and uncertainties, a nonconservative PID stabilization criterion for driver support systems is established. Some interesting results on positivity and connections of PID controllers are shown. Finally, some extreme point results on PID α-stabilization are obtained. These results give certain explanations and j.stifications for the simulation results performed at German Aerospace Research Center.

关键词： driver support systems PID controllers positivity uncertain parameters stabilization car steering systems parameter space extreme point results.

Large open-circuit voltage polymer solar cells by poly(3-hexylthiophene) with multi-adducts fullerenes

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Science China Chemistry 2012年第5期55卷 743-748页

作者： HEEGER Alan j. Department of Physics University of California Santa Barbara USA

Polymer solar cells (PSCs) made by poly(3-hexylthiophene) (P3HT) with multi-adducts fullerenes, [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), PC61BM-bisadduct (bisPC61BM) and PC61BM-trisadduct (trisPC61BM), were reported. Electrochemistry studies indicated that PC61BM, bisPC61BM and trisPC61BM had step-up distributional lowest unoccupied molecular orbital (LUMO) energy. PSCs made by P3HT with above PC61BMs show a trend of enlarged open-circuit voltages, which is in good agreement with the energy difference between the LUMO of PC61BMs and the HOMO of P3HT. On the contrary, reduced short-circuit currents (j.c) were observed. The investigation of photo responsibility, dynamics analysis based on photo-induced absorption of composite films, P3HT:PC61BMs and n-channel thin film field-effect transistors of PC61BMs suggested that the short polaron lifetimes and low carrier mobilities were response for reduced j.c. All these results demonstrated that it was important to develop an electron acceptor which has both high carrier mobility, and good compatibility with the electron donor conj.gated polymer for approaching high performance PSCs.

关键词： fullerene derivative large open circuit voltage polaron lifetime charge carrier mobility

High-resolution Induan-Olenekian boundary sequence in Chaohu, Anhui Province

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Science China Earth Sciences 2005年第3期48卷 291-297页

作者： Hans j. Hansen Geological Institute Copenhagen University Oster Voldgade 10 DK-1350 Copenhage Denmark

The West Pingdingshan Section in Chaohu, Southeast China’s Anhui Province is one of the potential GSSP candidates for the Induan-Olenekian boundary. Extensive study has been done on the Induan-Olenekian boundary strata at the section to meet the requirements of defining the GSSP precisely. This paper focuses on the boundary strata at the section to present a review of the main results achieved in recent years. The Induan-Olenekian boundary strata here cover an interval of about four meters at the West Pingdingshan Section, in which the key indices of defining the boundary and the chief transitional processes of some parameters at the boundary are included. The relationship between the boundaries defined by ammonoids and by conodonts is well clarified at the section. The magnetic polarity analysis shows that the boundary interval belongs to a normal polarity zone. Both the carbonate and organic carbon isotopes com- positions experienced a significant conversion in the boundary interval.

关键词： Lower Triassic, Induan-Olenekian boundary, GSSP, candidate, Chaohu of China.

Segregation of F-2 interspecific hybrid growth performance and wing color patterns relative to parental species in the Papilio machaon species group （Lepidoptera： Papilionidae）

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Insect Science 2007年第5期14卷 389-400页

作者： j. MARK SCRIBER Department of Entomology Michigan State University East Lansing Michigan USA

A strange Papilio female specimen with a prominent yellow wing band type very much like P. brevicauda （and also seen in P. machaon, and P. zelicaon） was captured in the forested mountains of southwest Vermont, USA. Despite its brevicauda-like appearance, it had mt-DNA of P. polyxenes. In eastern North America the P. brevicauda （Maritime Provinces of Canada） is currently believed to reflect previous （ancient） hybridization between ancestral P. machaon and P. polyxenes. It is uncertain whether the brevicauda-like wing trait features in the odd Vermont female may be a result of some introgression of P. machaon or P. brevicauda with P. polyxenes in eastern North America as seen also in the Ozark Mountains with P. j.anae. Nonetheless, the significance of wing trait analyses in relation to hybrid zones with P. polyxenes remains relevant. The segregation of wing color patterns and hostplant use abilities （efficiencies and growth rates） were examined for laboratory hand-paired F-2 hybrids of P. zelicaon ~ Papilio polyxenes relative to the parental species and primary hybrids. The black adult color pattern characterizing P. polyxenes is presumed to be inherited as a simple autosomal dominant. These hybrids were examined to determine：（i） how F-1 primary hybrid offspring perform relative to the parental types in survival, growth rates, and growth efficiencies; and （ii） whether these larval traits and the adult color patterns might be linked with wing morphology in the F-2 hybrids. While the F-1 hybrids grew as well as the P. polyxenes parent （P. zelicaon was significantly less efficient and slower in growth than either of these）, we could not convincingly determine whether the growth performances of the F-2 segregants were linked with the parental wing patterns.

关键词： hybrid swarms feeding efficiencies autosomai trait genetics Papilio polyxenes,Papilio zelicaon Papilio brevicauda

Impacts of climate warming on hybrid zone movement： Geographically diffuse and biologically porous ＂species borders＂

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Insect Science 2011年第2期18卷 121-159页

作者： j. Mark Scriber Department of Entomology Michigan State University East Lansing Michigan McGuire Center for Lepidoptera and Biodiversity Flonda Museum of Natural History University of Florida Gainesville Florida USA

The ecology and evolutionary biology of insect-plant associations has real- ized extensive attention, especially during the past 60 years. The classifications （categorical designations） of continuous variation in biodiversity, ranging from global patterns （e.g., lat- itudinal gradients in species richness/diversity and degree of herbivore feeding specialization） to localized insect-plant associations that span the biospectrum from polyphenisms, polymorphisms, biotypes, demes, host races, to cryptic species, remain academically contentious. Semantic and biosystematic （taxonomical） disagreements sometimes detract from more important ecological and evolutionary processes that drive diversification, the dynamics of gene flow and local extinctions. This review addresses several aspects of insect specialization, host-associated divergence and ecological （including ＂hybrid＂） speciation, with special reference to the climate warming impacts on species borders of hybridiz- ing swallowtail butterflies （Papilionidae）. Interspecific hybrid introgression may result in collapse of multi-species communities or increase species numbers via homoploid hybrid speciation. We may see diverging, merging, or emerging genotypes across hybrid zones, all part of the ongoing processes of evolution. Molecular analyses of genetic mosaics and genomic dynamics with ＂divergence hitchhiking＂, combined with ecological, ethological and physiological studies of＂species porosity＂, have already begun to unveil some answers for some important ecological/evolutionary questions. （i） How rapidly can host-associated divergence lead to new species （and why doesn＇t it always do so, e.g., resulting in ＂incom- plete＂ speciation）？（ii） How might ＂speciation genes＂ function, and how/where would we find them？（iii） Can oscillations from specialists to generalists and back to specialists help explain global diversity in herbivorous insects？（iv） How could recombinant interspecific hybridization lead to divergence an

关键词： cryptic species divergence hitchhiking ecologiealspeciation host associateddivergence mosaic genomes range limits recombinant hybrid species phylogeography,polyspecialists species boundaries

Large eddy simulation of turbulent diffusion flame combustion using a conserved scalar methodology

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航空动力学报 2007年第7期22卷 1106-1117页

作者： K. Wang Z. Yang j. j. McGuirk Department of Aeronautical and Automotive EngineeringLoughborough University Loughborough Leicestershire LE11 3TU UK

The present paper describes an LES prediction of turbulent diffusion flame combustion in a simplifled axi-symmetric combustor *** calculations are carried out using a well-tested finite volume incompressible LES code which has been modified to handle variable density and reacting *** basic mixture fraction conserved scalar method *** with the chemical state relationships described by fast *** turbulence-chemistry interaction is modelled by a sub-grid PDF method and the PDF is assumed to follow a Beta-function *** LES predictions have been time-averaged over 3.5 flow-through times to generate the mean radial profiles of mixture fraction,product mass fraction,temperature,axial velocity and axial *** agreement of the LES predictions with the experimental data is good for all the above quantities at four different axial positions with largest differences at the first measurement *** LES method also provides information on the unsteady nature of turbulent diffusion *** turbulent reacting flows with large density ratio,it was found necessary to use a relaxation method in order to remove unphysical high-frequency fluctuations and to maintain numerical stability.

关键词：大涡模拟湍流扩散数量方法论弛豫法燃烧理论

Laser cut hole matrices in novel armour plate steel for appliqué battlefield vehicle protection

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Defence Technology（防务技术） 2016年第5期12卷 351-359页

作者： Daniel j. THOMAS Engineering Manufacturing Centre College of Engineering Swansea University Swansea UK

During this research, experimental rolled homogeneous armour steel was cast, annealed and laser cut to form an appliqué plate. This Martensitic–Bainitic microstructure steel grade was used to test a novel means of engineering lightweight armour. It was determined that a laser cutting speed of 1200 mm/min produced optimum hole formations with limited distortion. The array of holes acts as a double-edged solution, in that they provide weight saving of 45%, providing a protective advantage and increasing the surface area. Data collected were used to generate laser cut-edge hole proj.ctions in order to identify the optimum cutting speed, edge condition, cost and deformation performance. These parameters resulted in the generation of a surface, with less stress raising features. This can result in a distribution of stress across the wider surface. Provided that appropriate process parameters are used to generate laser cut edges, then the hardness properties of the surface can be controlled. This is due to compressive residual stresses produced in the near edge region as a result of metallurgical transformations. This way the traverse cutting speed parameter can be adj.sted to alter critical surface characteristics and microstructural properties in close proximity to the cut-edge. A relationship was identified between the width of the laser HAZ and the hardness of the cut edge. It is the thickness of the HAZ that is affected by the laser process parameters which can be manipulated with adj.sting the traverse cutting speed.

关键词： Armour steels Defence systems Steel processing Armour engineering