摘要:

The candidate battery systems for electric vehicles have been evaluated on a common basis. The batteries with the highest probability of successful development and commercialization appear to be lead‐acid, nickel‐iron, nickel‐zinc, zinc‐chlorine, lithium‐metal sulfide, and sodium sulfur. The relative development risk was assessed and compared to the desirability of the corresponding batteries. No clear‐cut ’’winner’’ can be projected since each advanced battery has less than 50% probability of successful development. The overall probability that at least one of the batteries will be successfully developed by 2000 AD is judged greater than 75%.

ISSN:0094-243X    

DOI:10.1063/1.32335

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Most approaches to the assessment of fatique damage have been aimed at detecting fatigue cracks in the metal. This paper describes techniques for measuring the early accumulation of surface have stemmed from our investigations of exoelectron emisson (i.e. enhanced photoemission), which ocurs when the surface deformation produces microcracks in the natural the surface oxide film. Direct observations in a photoelectron microscope have shown that the oxide is ruptured by crystallagraphic slip in the underlying metal, so that the intensity of exoelectron emission is intimately related to the amount of fatigue deformation. An ultraviolet laser scanning system provides quantitative information on the distribution and extent of the deformation. An ultraviolet laser scanning system provides quantitative information on the distribution and extent of the deformation. The remaining fatigue life may be predicted from a quantitative assessment of damage. An electrochemical method, now being developed, provides a simpler means of measuring the development of microcracks in the surface oxide. The basic principle is to measure the flow of charge during electrochemical reoxidation of these microcracks. The distribution of the fatique damage is again revealed by a simple scanning procedure. Fatigue cracks only &angupr;50 &mgr;m in length have been detected in aluminum and the electrochemical reoxidation currents again provide a method of predicting fatigue life.

ISSN:0094-243X    

DOI:10.1063/1.32336

出版商:AIP    

年代:1981

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.32337

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An important challenge to the automotive industry is to develop a detailed understanding of the combustion of a wide variety of fuels. The development of accurate theories for combustion demands that the predictions of these theories be compared in detail to experiments. Recent advances in laser technology now permit one to measure accurately and nonintrusively both temperatures and species concentrations in combustion systems. An application of these measurements is given here to obtain a systematic comparison between a recent laminar methane‐air flame theory and measured temperature and species concentration profiles. These measurements are obtained by both laser Raman spectroscopy and laser induced fluorescence spectroscopy. The results show a good agreement between the theoretical predictions and the measured concentrations of CH4, O2, H2O, CO2and OH in several CH4‐air flames. An application of a sensitivity analysis to the kinetic reaction mechanism in the burned gas region of one of these flames allows a new value of the rate constant for the H+O2+M→HO2+M reaction to be inferred from the spectroscopic data.

ISSN:0094-243X    

DOI:10.1063/1.32338

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Ceramic ZrO2, TiO2and related oxides with suitable O2‐sensitive electrical properties have found important applications in devices for measuring exhaust‐gas O2concentration. For example, such devices are key components in feedback control systems that would maintain the intake air‐to‐fuel ratio near the stoichiometric value where regulated emissions can be minimized. The physical principles underlying the operation of ZrO2based O2‐concentration cells and TiO2‐based resistive devices for the stoichiometric application are described. Finally, a device based on electrochemical O2pumping is discussed which may be useful for A/F control in the fuel‐efficient lean region.

ISSN:0094-243X    

DOI:10.1063/1.32339

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In the automotive industry, solid surface effects are encountered in areas such as exhaust gas catalysis and sensing, corrosion, adhesion, friction and wear. Transition metals are involved in all of these types of interfaces. Our surface and interface physics programs are designed to characterize relevant physical phenomena in the atomistic sense. Transition metals are characterized in large part by their d‐electron behavior. The localized nature of the d‐orbitals has necessitated the formulation of a self‐consistent local orbital method in order to compute surface electronic structure. Results for the (100) surfaces on work functions agree well with experiment. We found a surprisingly large density of surface states, i.e., localized to the surface region, on palladium, copper, and silver. One‐fifth to one‐fourth of the electrons in the surface layer are in surface states on these metals. A prominent surface state band found theoretically on copper has subsequently have been observed by Heimannetal., and Kevan and Shirley via angular photoemission. It is clear that henceforth surface states will have to be considered in the analysis of physical and chemical processes on transition metal surfaces.

ISSN:0094-243X    

DOI:10.1063/1.32340

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A review article is presented of the author’s work on light emission from electron tunneling junctions. The light emission arises from the radiative decay of junction surface plasmon modes excited by tunneling electrons. The coupling out of the light is assisted by roughness and resonant particle scattering schemes. As a consequence of the quantum nature of the light generation process, there is a fundamental relation between the applied voltage and the observed emission spectrum. Because of the limited tunneling electron‐surface plasmon coupling, these thin‐film light sources have photometric brightnesses of only a few foot‐Lamberts. Other avenues of research for brighter thin‐film light sources are: development of metal electrodes having a lower surface plasmon frequency excitation of electronic transitions.

ISSN:0094-243X    

DOI:10.1063/1.32341

出版商:AIP    

年代:1981

数据来源: AIP