System simulation model for high-pressure metal hydride hydrogen storage systems

On-board hydrogen storage systems employing high-pressure metal hydrides promise advantages including high volumetric capacities and cold start capability. In this paper, we discuss the development of a system simulation model in Matlab/Simulink platform. Transient equations for mass balance and energy balance are presented. Appropriate kinetic expressions are used for the absorption/desorption reactions for the Ti_1.1CrMn metal hydride. During refueling, the bed is cooled by passing a coolant through tubes embedded within the bed while during driving, the bed is heated by pumping the radiator fluid through same set of tubes. The feasibility of using a high-pressure metal hydride storage system for automotive applications is discussed. Drive cycle simulations for a fuel cell vehicle are performed and detailed results are presented.     

Filtering error estimates and order of accuracy via the Peano Kernel Theorem

The Peano Kernel Theorem is introduced and a frequency domain derivation is given. It is demonstrated that the application of this theorem yields simple and accurate formulas for estimating the error introduced into a signal by filtering it to reduce noise. The concept of the order of accuracy of a filter is introduced and used as an organizing principle to compare the accuracy of different filters.     

Initial feasibility of a researcher configurable computerized self-monitoring system

This study sought to evaluate the feasibility of a researcher configurable self-monitoring program. An initial prototype of the program was developed as a Windows-based drag and drop flow chart interface for the researcher to construct the self-monitoring or diary protocol to be scheduled and displayed to the subject on a Pocket PC. The usability of the desktop researcher interface was evaluated in a small sample of medication trial researchers whose ratings of the prototype were generally positive and provided directions for improvement. The subject interface was then evaluated in an “analog” drug trial of 49 smokers using nicotine gum. These subjects were randomly assigned to either paper-based log or Pocket PC self-monitoring for 3 weeks. Pocket PC subjects were significantly more compliant than the log subjects on recording in the second (65% vs. 39%) and third (69% vs. 39%) weeks of the trial but did not differ from the log condition on total recording entries, likely due to the restrictions on retrospective recording in the Pocket PC program. This study provides support for the feasibility of a researcher configurable electronic diary system which should substantially reduce the programming barriers to electronic self-monitoring and increase the use of real-time monitoring in clinical and research venues.     

Solid-state intermetallic compound layer growth between copper and 95.5Sn-3.9Ag-0.6Cu solder

Long-term, solid-state intermetallic compound (IMC) layer growth was examined in 95.5Sn-3.9Ag-0.6Cu (wt.%)/copper (Cu) couples. Aging temperatures and times ranged from 70°C to 205°C and from 1 day to 400 days, respectively. The IMC layer thicknesses and compositions were compared to those investigated in 96.5Sn-3.5Ag/Cu, 95.5Sn-0.5Ag-4.0Cu/Cu, and 100Sn/Cu couples. The nominal Cu₃Sn and Cu₆Sn₅ stoichiometries were observed. The Cu₃Sn layer accounted for 0.4–0.6 of the total IMC layer thickness. The 95.5Sn-3.9Ag-0.6Cu/Cu couples exhibited porosity development at the Cu₃Sn/Cu interface and in the Cu₃Sn layer as well as localized “plumes” of accelerated Cu₃Sn growth into the Cu substrate when aged at 205°C and t>150 days. An excess of 3–5at.%Cu in the near-interface solder field likely contributed to IMC layer growth. The growth kinetics of the IMC layer in 95.5Sn-3.9Ag-0.6Cu/Cu couples were described by the equation x=x_o+Atⁿexp [−ΔH/RT]. The time exponents, n, were 0.56±0.06, 0.54±0.07, and 0.58±0.07 for the Cu₃Sn layer, the Cu₆Sn₅, and the total layer, respectively, indicating a diffusion-based mechanism. The apparent-activation energies (ΔH) were Cu₃Sn layer: 50±6 kJ/mol; Cu₆Sn₅ layer: 44±4 kJ/mol; and total layer: 50±4 kJ/mol, which suggested a fast-diffusion path along grain boundaries. The kinetics of Cu₃Sn growth were sensitive to the Pb-free solder composition while those of Cu₆Sn₅ layer growth were not so.     

Social Transmission of Flavor Preferences in Two Species of Hamsters (Mesocricetus auratus and Phodopus campbelli).

Golden hamsters (Mesocricetus auratus) and dwarf hamsters (Phodopus campbelli) interacted with a conspecific demonstrator that had recently consumed a flavored food. When given a choice between their demonstrator's flavor and another flavor, the dwarf hamsters preferred the flavor their demonstrator had eaten. Golden hamsters did not prefer their demonstrators' diets when the demonstrators were unrelated adults or littermates, but they did when the demonstrator was their mother. Videotaping the interactions between demonstrators and observers revealed that adult golden hamsters did not investigate foods hoarded by their demonstrators whereas dwarf hamsters did. These results are interpreted in terms of the stimuli that activate feeding behavior systems in these 2 hamster species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tetramethylammonium 3-aminopropyl dimethylsilanolate—aminopropyl dimethylsilanolate—a new catalyst for the synthesis of high purity,high molecular weight α,ω-bis(aminopropyl) polydimethylsiloxanes

Tetramethylammonium 3-aminopropyl dimethylsilanolate, readily prepared from bis(3-aminopropyl) tetramethyldisiloxane and tetramethyl-ammonium hydroxide pentahydrate, has been found to serve as a highly effective catalyst for the ring opening polymerization of cyclic siloxanes with an end blocker such as bis(3-aminopropyl) tetramethyldisiloxane to give aminopropyl terminated linear polydimethylsiloxanes. By following a novel two stage procedure, even high molecular weight (5,000–55,000 g/mol) silicone diamines were able to be prepared in a high state of purity; chain extension reactions of these diamines with diisocyanates gave a series of high molecular weight silicone polyureas with good elastomeric properties.     

Effect of ethanol on low density lipoprotein and platelet composition

The present study was designed to investigate the effect of ethanol (EtOH) dose on low density lipoprotein (LDL) and platelet composition. Male squirrel monkeys were divided into three groups designated Control, Low, and High EtOH, and fed isocaloric liquid diets containing 0%, 12%, and 24% of calories as EtOH, respectively. After four months of treatment, monkeys fed the 12% alcohol dose had LDL and platelet cholesterol concentrations similar to Controls. By contrast, platelet membranes from High EtOH animals contained significantly more cholesterol which was associated with higher levels of plasma LDL cholesterol and apolipoprotein B. Blood platelet count, size, and mass were similar for all groups and circulating platelet aggregates were absent in the two alcohol cohorts. Despite elevations in platelet cholesterol mass and thromboxane A₂ (TXA₂) precursor, phospholipid arachidonate, platelet responsiveness, measured as thromboxane formed in response to a collagen challengein vitro, and the cholesterol/phospholipid molar ration, were not significantly altered by high dose alcohol. Normal platelet activity in High EtOH monkeys may have resulted from a significant increase in the platelet phospholipid polyunsaturated/saturated fatty acid ratio and a non-significant increase in platelet phospholipid mass, both of which would have a fluidizing effect on platelet membranes. Our data indicate that low EtOH intake has no effect on platelet composition and function while unfavorable platelet cholesterol enrichment following consumption of high dose ethanol may arise from elevations in plasma LDL. Potentially thrombogenic (TXA₂ formation, platelet aggregate formation) consequences of increased platelet cholesterol in squirrel monkeys fed high levels of alcohol may be averted by compensatory physicochemical changes in platelet membrane lipid composition although persistent elevations in circulating LDL may contribute to increased risk of cardiovascular disease.     

An adaptive approach to human decision making: Learning theory, decision theory, and human performance.

Describes a general model of decision rule learning, the rule competition model, composed of 2 parts: an adaptive network model that describes how individuals learn to predict the payoffs produced by applying each decision rule for any given situation and a hill-climbing model that describes how individuals learn to fine tune each rule by adjusting its parameters. The model was tested and compared with other models in 3 experiments on probabilistic categorization. The 1st experiment was designed to test the adaptive network model using a probability learning task, the 2nd was designed to test the parameter search process using a criterion learning task, and the 3rd was designed to test both parts of the model simultaneously by using a task that required learning both category and cutoff criteria. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regression analyses of repeated measures data in cognitive research.

Repeated measures designs involving nonorthogonal variables are being used with increasing frequency in cognitive psychology. Researchers usually analyze the data from such designs inappropriately, probably because the designs are not discussed in standard textbooks on regression. Two commonly used approaches to analyzing repeated measures designs are considered in this article. It is argued that both approaches use inappropriate error terms for testing the effects of independent variables. A more appropriate analysis is presented, and two alternative computational procedures for the analysis are illustrated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accelerated Aging in 3-mol%-Yttria-Stabilized Tetragonal Zirconia Ceramics Sintered in Reducing Conditions

The aging behavior of 3-mol%-yttria-stabilized tetragonal zirconia (3Y-TZP) ceramics sintered in air and in reducing conditions was investigated at 140°C in water vapor. It was observed by X-ray diffraction (XRD) that 3Y-TZP samples sintered in reducing conditions exhibited significantly higher tetragonal-to-monoclinic transformation than samples with similar density and average grain size values but obtained by sintering in air. This fact is explained by the increase of the oxygen vacancy concentration and by the presence at the grain boundary region of a new aggregate phase formed because of the exolution of Fe²⁺ ions observed by X-ray photoelectron spectroscopy.