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701.
Measurements show that the dynamic charge acceptance (DCA) of flooded SLI lead-acid batteries during micro-cycling in conventional and micro-hybrid vehicles is strongly dependent on the short-term history, such as previous charge or discharge, current rate, lowest state of charge in the last 24 h and more. Factors of 10 have been reported. Inhomogeneous current distribution, especially as a result of acid stratification, has been suggested to explain the DCA variability.This hypothesis was investigated by simulation of a two-dimensional macrohomogeneous model. It provides a spatial resolution of three elements in horizontal direction in each electrode and three elements in vertical direction. For an existing set of parameters, different current profiles were analyzed with regard to the current distribution during charging and discharging.In these simulations, a strong impact of the short-term history on current, charge and acid density distribution was found as well as a strong influence of micro-cycles on both charge distribution and acid stratification. 相似文献
702.
James W. McCauley Parimal Patel Mingwei Chen Gary Gilde Elmar Strassburger Bhasker Paliwal K.T. Ramesh Dattatraya P. Dandekar 《Journal of the European Ceramic Society》2009,29(2):223-236
In the early 1970s in Japan, the United States and France it was found that additions of nitrogen into aluminum oxide resulted in new spinel-like phases. At about the same time there was much increased interest in oxynitrides, stimulated by Professor K. Jack in the UK and Y. Oyama in Japan. Following these activities a major research program in this area was initiated at the Army Materials and Mechanics Research Center in Watertown, Massachusetts in 1974. These efforts resulted in the first complete Al2O3–AlN phase equilibrium diagram and a process to reactively sinter to nearly full density, translucent aluminum oxynitride spinel ceramic, which was named AlON. Subsequently, the Raytheon Company further developed AlON into a highly transparent material (ALON?) with many applications including transparent armor and EM domes and windows, among others—the technology was recently transferred to the Surmet Corporation. This paper will review the early history, phase equilibrium, crystal chemistry, and properties of this material, along with more recent work in our laboratory on transient liquid phase sintering and new data on lattice parameter measurements. In addition, recent results of collaborative work on AlON's dynamic mechanical properties using plate impact, Kolsky bar and edge-on impact (EoI) experimental techniques, including preliminary modeling at the microstructural scale of AlON in the EoI test, will be presented. 相似文献
703.
O. Lupan L. Chow E. Monaico V. ?ontea A. Naitabdi A. Schulte 《Materials Research Bulletin》2009,44(1):63-163
Nanostructured ZnO thin films have been deposited using a successive chemical solution deposition method. The structural, morphological, electrical and sensing properties of the films were studied for different concentrations of Al-dopant and were analyzed as a function of rapid photothermal processing temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron and micro-Raman spectroscopy. Electrical and gas sensitivity measurements were conducted as well. The average grain size is 240 and 224 Å for undoped ZnO and Al-doped ZnO films, respectively. We demonstrate that rapid photothermal processing is an efficient method for improving the quality of nanostructured ZnO films. Nanostructured ZnO films doped with Al showed a higher sensitivity to carbon dioxide than undoped ZnO films. The correlations between material compositions, microstructures of the films and the properties of the gas sensors are discussed. 相似文献
704.
Tatiana K. Madsen Frank H. P. Fitzek Ramjee Prasad Gerrit Schulte 《Wireless Personal Communications》2005,35(1-2):135-151
The paper presents a new approach investigating mobile ad hoc network connectivity. It is shown how to define and evaluate the connectivity probability of a mobile network where the position of the nodes and the link quality changes over time. The connectivity probability is a measure that can capture the impact of the node movement on the network connectivity. A number of mobility models is considered ranging from the classical Random Direction model to the Virtual World model based on the mobility measurements of a multi–player game. We introduce an Attractor model as a simple way to model non–homogeneous node distribution by incorporating viscosity regions in the simulation area. Methods of ergodic theory are used to show the correctness of the approach and to reduce the computational time. Simulation results show how the node density distribution affects the network connectivity. 相似文献
705.
706.
Bar D Tauer LW Bennett G González RN Hertl JA Schukken YH Schulte HF Welcome FL Gröhn YT 《Journal of dairy science》2008,91(6):2205-2214
The objective of this study was to estimate the cost of generic clinical mastitis (CM) in high-yielding dairy cows given optimal decisions concerning handling of CM cases. A specially structured optimization and simulation model that included a detailed representation of repeated episodes of CM was used to study the effects of various factors on the cost of CM. The basic scenario was based on data from 5 large herds in New York State. In the basic scenario, 92% of the CM cases were recommended to be treated. The average cost of CM per cow and year in these herds was $71. The average cost of a CM case was $179. It was composed of $115 because of milk yield losses, $14 because of increased mortality, and $50 because of treatment-associated costs. The estimated cost of CM was highly dependent on cow traits: it was highest ($403) in cows with high expected future net returns (e.g., young, high-milk-yielding cows), and was lowest ($3) in cows that were recommended to be culled for reasons other than mastitis. The cost per case of CM was 18% higher with a 20% increase in milk price and 17% lower with a 20% decrease in milk price. The cost per case of CM was affected little by a 20% change in replacement cost or pregnancy rate. Changes in CM incidence, however, resulted from changes in these factors, thus affecting whole-farm profitability. The detailed results obtained from this insemination and replacement optimization model can assist farmers in making CM treatment decisions. 相似文献
707.
M. Brass T. Pritzel E. Schulte J. U. Keller 《International Journal of Thermophysics》2000,21(4):883-898
A static method has been used to obtain vapor–liquid equilibrium data for the systems ammonia (NH3)–water (H2O)–potassium hydroxide (KOH) and ammonia–water–sodium hydroxide (NaOH) at temperatures of 303 and 318 K and pressures from 0.1 to 1.3 MPa. The salt concentration in the liquid phase was chosen in the range from 2 to 60 mass% salt in water. In both systems NH3–H2O–NaOH and NH3–H2O–KOH, solid–liquid–vapor equilibria were observed. In the NH3–H2O–KOH system, liquid–liquid–vapor equilibrium was observed at 318 K and 1.1 MPa but at yet unknown concentrations of the liquid phases. 相似文献
708.
Liu J Redmond MJ Brodsky EK Alexander AL Lu A Thornton FJ Schulte MJ Grist TM Pipe JG Block WF 《IEEE transactions on medical imaging》2006,25(2):148-157
Time-resolved contrast-enhanced magnetic resonance (MR) angiography (CE-MRA) has gained in popularity relative to X-ray Digital Subtraction Angiography because it provides three-dimensional (3-D) spatial resolution and it is less invasive. We have previously presented methods that improve temporal resolution in CE-MRA while providing high spatial resolution by employing an undersampled 3-D projection (3D PR) trajectory. The increased coverage and isotropic resolution of the 3D PR acquisition simplify visualization of the vasculature from any perspective. We present a new algorithm to develop a set of time-resolved 3-D image volumes by preferentially weighting the 3D PR data according to its acquisition time. An iterative algorithm computes a series of density compensation functions for a regridding reconstruction, one for each time frame, that exploit the variable sampling density in 3D PR. The iterative weighting procedure simplifies the calculation of appropriate density compensation for arbitrary sampling patterns, which improve sampling efficiency and, thus, signal-to-noise ratio and contrast-to-noise ratio, since it is does not require a closed-form calculation based on geometry. Current medical workstations can display these large four-dimensional studies, however, interactive cine animation of the data is only possible at significantly degraded resolution. Therefore, we also present a method for interactive visualization using powerful graphics cards and distributed processing. Results from volunteer and patient studies demonstrate the advantages of dynamic imaging with high spatial resolution. 相似文献
709.
Ionic liquid matrixes (ILM) have been shown to allow very homogeneous sample preparations, facilitating relative quantifications using internal standards in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). In the present work, the ability to perform quantifications of peptides without using internal standards in these matrixes was investigated. Linear correlations between peptide amount and signal intensities could be observed when increased molar matrix-to-analyte ratios were applied. The dynamic range of linearity was approximately 1 order of magnitude. The method was applied successfully to monitor the time-dependent evolution of substrates and products in trypsin-catalyzed digests of single peptides and peptide mixtures. Thus, ionic liquid matrixes allow quantitative MALDI-MS without the need for internal standards, making the method a suitable tool for the fast screening of new enzymes or the search for substrates or inhibitors. 相似文献
710.
Exact geometric calibration of optical devices like projectors or cameras is the basis for utilizing them in quantitative metrological applications. The common state-of-the-art photogrammetric pinhole-imaging-based models with supplemental polynomial corrections fail in the presence of nonsymmetric or high-spatial-frequency distortions and in describing caustics efficiently. These problems are solved by our vision ray calibration (VRC), which is proposed in this paper. The VRC takes an optical mapping system modeled as a black box and directly delivers corresponding vision rays for each mapped pixel. The underlying model, the calibration process, and examples are visualized and reviewed, demonstrating the potential of the VRC. 相似文献