Effect of engine-based thermal aging on surface morphology and performance of Lean NOx Traps

A small single-cylinder diesel engine is used to thermally age model (Pt + Rh/Ba/γ-Al₂O₃) lean NO_x traps (LNTs) under lean/rich cycling at target temperatures of 600 °C, 700 °C, and 800 °C. During an aging cycle, fuel is injected into the exhaust to achieve reproducible exotherms under lean and rich conditions with the average temperature approximating the target temperature. Aging is performed until the cycle-average NO_x conversion measured at 400 °C is approximately constant. Engine-based NO_x conversion decreased by 42% after 60 cycles at 600 °C, 36% after 76 cycles at 700 °C and 57% after 46 cycles at 800 °C. The catalyst samples were removed and characterized by XRD and using a microreactor that allowed controlled measurements of surface area, precious metal size, NO_x storage, and reaction rates. Three aging mechanisms responsible for the deactivation of LNTs have been identified: (i) loss of dispersion of the precious metals, (ii) phase transitions in the washcoat materials, and (iii) loss of surface area of the storage component and support. These three mechanisms are accelerated when the aging temperature exceeds 850 °C—the γ to δ transition temperature of Al₂O₃. Normalization of rates of NO reacted at 400 °C to total surface area demonstrates the biggest impact on performance stems from surface area losses rather than from precious metal sintering.     

下一代显示接口新标准--DisplayPort

随着显示技术逐渐转移到高性能的平板以及微电子技术,业界需要一种可扩充、开放产业标准的数字接口,以及可以把功能升级的解决方案。这种可升级的显示接口,应能满足企业以及一般消费者的各种需求。DisplayPort就是这种下一代的显示接口,可以为PC、监视器、显示面板、投影仪、以     

Physical Properties of Vegetable Oil and Chlorinated Ethene Mixtures

Laboratory experiments were conducted to investigate the abiotic interactions of soybean oil (SoyOil) and chlorinated ethene (CE) nonaqueous phase liquids (NAPLs). The mixed NAPL density and interfacial tension behaved ideally, as predicted by the volume ratio. The mixed NAPL viscosity increased exponentially from that of the pure CE to that of pure SoyOil as the volume fraction increased. The measured contact angle was highly variable and was unpredictable as a function of the volume composition of the mixed NAPL. The physical property effects indicate that the mobilization of residual CE NAPLs because of SoyOil injection is unlikely. Equilibrium dissolution of CEs from the NAPL mixtures behaved linearly as a function of the mole fraction. Dissolved SoyOil in simulated groundwater enhanced the dissolution of trichloroethene (TCE) during flow tests, increasing the effluent TCE concentration from 141?to?202?mg/L. The ready intermingling of the CE dense nonaqueous phase liquids (DNAPLs) and SoyOil indicate that such interactions may be significant at sites where vegetable oil is injected into DNAPL source areas to enhance in situ anaerobic bioremediation.     

Childhood Sexual and Physical Abuse and the 1-Year Prevalence of Medical Problems in the National Comorbidity Survey.

In a population sample (N = 5,877; ages 15 to 54), the authors found childhood sexual and physical abuse to be associated with the 1-year prevalence of serious health problems for both men and women. The authors also found that participants' psychiatric disorders partially mediated the effects of physical and sexual abuse on adult health. However, childhood abuse continued to independently influence health status after the authors controlled for psychiatric disorders. Contrary to expectations, individuals who experienced a combination of sexual and physical abuse did not have a higher frequency of health problems than those who experienced either type of abuse alone. Implications for these findings are discussed, including possible mechanisms that may account for the association between childhood abuse and adult health problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of sample size in the nucleation kinetics of phase transformations in steel alloys

Certain commercial steel alloys exhibit a two-step phase transformation process during solidification when substantial undercooling of the liquid allows access to the metastable phase. This two-step transformation leads to a desirable microstructure under certain conditions. Electrostatic Levitation (ESL) and Electromagnetic Levitation (EML) are two methods of containerless processing used to study how nucleation and growth kinetics influence the transformation delay between phases. Because the two facilities show substantially different delay results, the test environment differences have been analyzed to determine the root cause of this deviation. In particular, the difference in sample size between ESL and EML is examined and modeling shows that this difference is not the controlling factor in determining transformation delay behavior.     

Development of a measure for the information technology infrastructure construct

The goal of this research was to operationalize the information technology infrastructure (ITI) concept by identifying its underlying dimensions and establishing a valid and reliable measure for the construct. In order to accomplish this task with the highest degree of certainty, two approaches were sequentially applied: exploratory factor analysis and confirmatory factor analysis. In evaluating the confirmatory factor model, a step-by-step process was employed, assessing unidimensionality, reliability, discriminant validity, and nomological validity. The dimensions of ITI were determined to be: Chief Information Officer, IT Planning, IT Security, Technology Integration, Advisory Committee, Enterprise Model, and Data Administration. Researchers may now make use of this validated ITI measure to conduct investigations of ITI and other organizational measures. Implications of the ITI measure with other organizational initiatives such as electronic commerce and knowledge management are explored.     

A real-time vision module for interactive perceptual agents

Abstract. Interactive robotics demands real-time visual information about the environment. Real-time vision processing, however, places a heavy load on the robot's limited resources, which must accommodate multiple other processes running simultaneously. This paper describes a vision module capable of providing real-time information from ten or more operators while maintaining at least a 20-Hz frame rate and leaving sufficient processor time for a robot's other capabilities. The vision module uses a probabilistic scheduling algorithm to ensure both timely information flow and a fast frame capture. In addition, it tightly integrates the vision operators with control of a pan-tilt-zoom camera. The vision module makes its information available to other modules in the robot architecture through a shared memory structure. The information provided by the vision module includes the operator information along with a time stamp indicating information relevance. Because of this design, our robots are able to react in a timely manner to a wide variety of visual events.     

Rapid Anisotropic Diffusion Using Space-Variant Vision

Many computer and robot vision applications require multi-scale image analysis. Classically, this has been accomplished through the use of a linear scale-space, which is constructed by convolution of visual input with Gaussian kernels of varying size (scale). This has been shown to be equivalent to the solution of a linear diffusion equation on an infinite domain, as the Gaussian is the Green's function of such a system (Koenderink, 1984). Recently, much work has been focused on the use of a variable conductance function resulting in anisotropic diffusion described by a nonlinear partial differential equation (PDE). The use of anisotropic diffusion with a conductance coefficient which is a decreasing function of the gradient magnitude has been shown to enhance edges, while decreasing some types of noise (Perona and Malik, 1987). Unfortunately, the solution of the anisotropic diffusion equation requires the numerical integration of a nonlinear PDE which is a costly process when carried out on a uniform mesh such as a typical image. In this paper we show that the complex log transformation, variants of which are universally used in mammalian retino-cortical systems, allows the nonlinear diffusion equation to be integrated at exponentially enhanced rates due to the nonuniform mesh spacing inherent in the log domain. The enhanced integration rates, coupled with the intrinsic compression of the complex log transformation, yields a speed increase of between two and three orders of magnitude, providing a means of performing rapid image enhancement using anisotropic diffusion.     

Low temperature UV/ozone oxidation formation of HfSiON gate dielectric

Physical and electrical properties of hafnium silicon oxynitride (HfSi_xO_yN_z) dielectric films prepared by UV ozone oxidation of hafnium silicon nitride (HfSiN) followed by annealing to 450 °C are reported. Interfacial layer growth was minimized through room temperature deposition and subsequent ultraviolet/ozone oxidation. The capacitance–voltage (C–V) and current–voltage (I–V) characteristics of the as-deposited and annealed HfSi_xO_yN_z are presented. These 4 nm thick films have a dielectric constant of 8–9 with 12 at.% Hf composition, with a leakage current density of 3×10⁻⁵ A/cm² at V_fb+1 V. The films have a breakdown field strength >10 MV/cm.