Technology Evaluation of Hydrogen Light-Duty Vehicles

This study analyzed candidate hydrogen-fueled vehicles for near and long-term use associated with their efficiency, performance, and emissions. Various types of hydrogen-fueled vehicles were assessed using Argonne National Laboratory's Powertrain System Analysis Toolkit vehicle simulation model. These include hythane- and hydrogen-fueled internal combustion engines (ICEs), hydrogen-fueled hybrid electric propulsion, and direct hydrogen fuel cells. Vehicle sizes and configurations, consistent with the available component models/data, were simulated to compare efficiency and emissions with baseline conventional vehicles. The simulations provided salient information on the vehicle characteristics, performance, and efficiency, as functions of operating conditions on standard driving cycles. It was found that substantial gains in fuel economy can be achieved through hybridization both for conventional and fuel cell vehicles. When hybridized, hydrogen ICE configurations achieve similar fuel economy to gasoline counterparts. The results also confirm that ICE hybrid electric vehicles (HEV) achieve higher fuel economy than fuel cell configurations and comparable results with fuel cell HEV. Comparison of efficiency results for various driving cycles further indicates that cycles with low power demand are most suited for hybrid operations.     

Palladium‐Catalyzed [2+1] Cycloadditions Affording Vinylidenecyclopropanes as Precursors of 7‐Membered Carbocycles

Palladium(II) acetate in association with secondary phosphine oxides provides an efficient catalytic system for [2+1] cycloadditions starting from oxanorbornene derivatives and tertiary propargyl esters giving rise to vinylidenecyclopropanes. This reaction is specific to bidentate phosphinito–phosphinous acid ligands generated from secondary phosphine oxides. The [2+1] cycloaddition was found broad in scope with a high tolerance to various functional groups. Moreover, vinylidenecyclopropanes were straightforwardly converted into oxabicyclo[3.2.1]oct‐2‐ene derivatives through a palladium‐catalyzed ring‐expansion. Finally, the oxa bridge cleavage of oxatricyclic compounds yields functionalized 7‐membered carbocycles.

     

A domain-specific language to design false data injection tests for air traffic control systems

International Journal on Software Tools for Technology Transfer - The ADS-B—automatic dependent surveillance-broadcast—technology requires aircraft to broadcast their position and...     

Beneficial Effect of Pt and of Pre-Oxidation on the Oxidation Behaviour of an NiCoCrAlYTa Bond-Coating for Thermal Barrier Coating Systems

The oxidation behaviour of a thermal barrier coating (TBC) system is a major concern as the growth of the thermally grown oxide (TGO) layer on the bond-coating creates stresses that greatly favour the thermal barrier spallation. To delay the loss of the thermal protection provided, research has focused on the bond-coating composition and microstructure as well as on the parameters required for a suitable pre-oxidation treatment before the deposition of the ceramic top coat. Platinum is known to enhance the oxidation/corrosion resistance of MCrAlY coatings. The effect of Pt on the oxidation behaviour of a NiCoCrAlYTa coating was assessed in this study. In addition, pre-oxidation treatments were conducted to determine if the oxidation behaviour of the modified NiCoCrAlYTa coating could be further improved.     

真空渗碳后的淬火工艺

本文论述了经低压真空渗碳后的工件淬火时选择油淬或气淬的原因及影响因素.通过采用变速驱动(VSD)、选择适合的钢材、新型混合气体等新的技术手段,真空渗碳加气淬可以有效地减小工件地变形并显著地提高热处理质量及其稳定性.可以应用于绝大部分汽车齿轮工件的热处理.     

Advanced burner-rig test for oxidation-corrosion resistance evaluation of MCrAlY/superalloys systems

Protective coatings are used on gas turbine components to enable them to survive in engine-operating conditions. This study presents a recently developed cyclic burner-rig test that is used to simulate helicopter engine conditions and to assess the oxidation and hot corrosion behaviour of MCrAlY coatings on nickel-base superalloys. A diluted sea-salt solution is atomised into the burner-rig to simulate hot-corrosion. Each cycle lasts 1 h with temperatures varying in the range of 900 °C to 1000 °C followed by 15 min cooling to room temperature. Specimens are tested up to 1000 such cycles. Three different NiCoCrAlYTa coating thicknesses are used to determine the influence of the Al reservoir on the lifetime of the coated MC2 superalloy. The evolving microstructural features are identified using high resolution scanning electron microscopy and energy dispersive spectroscopy and compared with isothermal testing in pure oxidising conditions. The NiCoCrAlYTa microstructure obtained after the burner-rig test has typical features of a Type 1 hot corrosion degradation, with internal oxidation and nitruration and a front of chromium and yttrium-rich sulphides. This type of advanced burner-rig test cycle is successful in reproducing the accelerated combined hot-corrosion/oxidation damage.     

Micro-diffraction Investigation of Localized Strain in Mesa-etched HgCdTe Photodiodes

We present an x-ray micro-diffraction investigation of localized strain and lattice disorientation in HgCdTe layers with a submicronic resolution using a synchrotron white beam in Laue configuration. Diffraction peak displacement mapping evidences bending of the crystal planes around mesa-etched photodiodes, with strong dependence upon the processing steps. The etching step by itself does not induce any deformation within the layer, while the passivation step leads to sufficient strain for plastic deformation to occur at the lateral edges of the etching. The annealing step is found to have a healing effect on the layer, which reduces the overall deformation and even re-crystallizes plastically deformed areas of the layer.     

Statistical analysis of a database of absorption spectra of phytoplankton and pigment concentrations using self-organizing maps

We present a statistical analysis of a large set of absorption spectra of phytoplankton, measured in natural samples collected from ocean water, in conjunction with detailed pigment concentrations. We processed the absorption spectra with a sophisticated neural network method suitable for classifying complex phenomena, the so-called self-organizing maps (SOM) proposed by Kohonen [Kohonen, Self Organizing Maps (Springer-Verlag, 1984)]. The aim was to compress the information embedded in the data set into a reduced number of classes characterizing the data set, which facilitates the analysis. By processing the absorption spectra, we were able to retrieve well-known relationships among pigment concentrations and to display them on maps to facilitate their interpretation. We then showed that the SOM enabled us to extract pertinent information about pigment concentrations normalized to chlorophyll a. We were able to propose new relationships between the fucoxanthin/Tchl-a ratio and the derivative of the absorption spectrum at 510 nm and between the Tchl-b/Tchl-a ratio and the derivative at 640 nm. Finally, we demonstrate the possibility of inverting the absorption spectrum to retrieve the pigment concentrations with better accuracy than a regression analysis using the Tchl-a concentration derived from the absorption at 440 nm. We also discuss the data coding used to build the self-organizing map. This methodology is very general and can be used to analyze a large class of complex data.     

Definition of spacing constraints for the car sequencing problem

A car sequencing problem deals with the ordering of a list of vehicles to be produced on an assembly line so that the overall capacity of each work station is not exceeded. Some types of vehicles require several time-consuming operations to be done on a work station and will naturally overload that work station. Such vehicles are spaced out in the sequence, by means of a set of spacing constraints, in order to cope with the momentary increase of workload that they create. Two questions arise: which type of vehicles should be subject to the spacing constraints and by which distance should they be spaced out in the sequence. In practice as well as in the car sequencing literature, there does not exist a methodical way to answer the first question and the existing methods for the second one is no longer adequate due to the increased diversity of cars produced in an assembly line. In this paper, we propose two new methods to answer these questions with a special emphasis on the first one. The performance of the proposed methods is illustrated using a real case study.