Simulation of abuse tolerance of lithium-ion battery packs

A simple approach for using accelerating rate calorimetry data to simulate the thermal abuse resistance of battery packs is described. The thermal abuse tolerance of battery packs is estimated based on the exothermic behavior of a single cell and an energy balance than accounts for radiative, conductive, and convective heat transfer modes of the pack. For the specific example of a notebook computer pack containing eight 18650-size cells, the effects of cell position, heat of reaction, and heat-transfer coefficient are explored. Thermal runaway of the pack is more likely to be induced by thermal runaway of a single cell when that cell is in good contact with other cells and is close to the pack wall.     

Electrical properties of metal/Langmuir-Blodgett (polymeraldine base) layer/metal devices

Metal-insulator-metal structures have been fabricated by sandwiching polyemeraldine base Langmuir-Blodgett (LB) films between metals like silver and indium vacuum-deposited onto indium-tin-oxide (ITO) glass. These devices have been found to exhibit insulating properties in the absence of a metal oxide layer. Current (I)-voltage (V) and capacitance (C)-voltage (V) measurements have been carried out on such devices. It is seen that these devices show rectification behavior at about 3 V for both forward and reverse bias conditions. However, at low voltages, nonlinear and asymmetric behaviors have been observed, whereas plot of log 1 versus V^1/4 indicates linear characteristics at high fields. The value of the barrier height has been found to be about 1.2 V in agreement with literature, implying Schottky behavior. © 1997 John Wiley & Sons, Inc.     

Corrosion protection of steel by polyaniline (PANI) pigmented paint coating

The corrosion performance of polyaniline (PANI) pigmented coating on steel has been studied by electrochemical impedance spectroscopy (EIS) in 3% NaCl and 0.1N HCl solutions. Initially, the impedance values were found to decrease due to the corrosion of steel in pin holes of the coating. However, on increased exposure time, the impedance values were found to increase due to the formation of passive film on the exposed steel in pin holes. These studies have shown that the polyaniline pigmented coatings are able to protect the steel both in acid and neutral media.     

Approximation Algorithms for Average Stretch Scheduling

We study the basic problem of preemptive scheduling of a stream of jobs on a single processor. Consider an on-line stream of jobs, and let the ith job arrive at time r(i) and have processing time p(i). If C(i) is the completion time of job i, then the flow time of i is C(i) − r(i) and the stretch of i is the ratio of its flow time to its processing time; that is, . Flow time measures the time that a job is in the system regardless of the service it requests; the stretch measure relies on the intuition that a job that requires a long service time must be prepared to wait longer than jobs that require small service times. We present the improved algorithmic results for the average stretch metric in preemptive uniprocessor scheduling. Our first result is an off-line polynomial-time approximation scheme (PTAS) for average stretch scheduling. This improves upon the 2-approximation achieved by the on-line algorithm srpt that always schedules a job with the shortest remaining processing time. In a recent work, Chekuri and Khanna (Proc. 34th Ann. Symp. Theory Comput., 297–305, 2002) have presented approximation algorithms for weighted flow time, which is a more general metric than average stretch; their result also yields a PTAS for average stretch. Our second set of results considers the impact of incomplete knowledge of job sizes on the performance of on-line scheduling algorithms. We show that a constant-factor competitive ratio for average stretch is achievable even if the processing times (or remaining processing times) of jobs are known only to within a constant factor of accuracy.     

MOSFET-like CNFET based logic gate library for low-power application: a comparative study

The next generation of logic gate devices are expected to depend upon radically new technologies mainly due to the increasing difficulties and limitations of existing CMOS technology. MOSFET like CNFETs should ideally be the best devices to work with for high-performance VLSI. This paper presents results of a comprehensive comparative study of MOSFET-like carbon nanotube field effect transistors (CNFETs) technology based logic gate library for high-speed, low-power operation than conventional bulk CMOS libraries. It focuses on comparing four promising logic families namely: complementary-CMOS (C-CMOS), transmission gate (TG), complementary pass logic (CPL) and Domino logic (DL) styles are presented. Based on these logic styles, the proposed library of static and dynamic NAND-NOR logic gates, XOR, multiplexer and full adder functions are implemented efficiently and carefully analyzed with a test bench to measure propagation delay and power dissipation as a function of supply voltage. This analysis provides the right choice of logic style for low-power, high-speed applications. Proposed logic gates libraries are simulated using Synopsys HSPICE based on the standard 32 nm CNFET model. The simulation results demonstrate that, it is best to use C-CMOS logic style gates that are implemented in CNFET technology which are superior in performance compared to other logic styles, because of their low average power-delay-product (PDP). The analysis also demonstrates how the optimum supply voltage varies with logic styles in ultra-low power systems. The robustness of the proposed logic gate library is also compared with conventional and state-art of CMOS logic gate libraries.     

One-pass wavelet decompositions of data streams

We present techniques for computing small space representations of massive data streams. These are inspired by traditional wavelet-based approximations that consist of specific linear projections of the underlying data. We present general "sketch"-based methods for capturing various linear projections and use them to provide pointwise and rangesum estimation of data streams. These methods use small amounts of space and per-item time while streaming through the data and provide accurate representation as our experiments with real data streams show.     

Effects of Lime Amendment on the pH of Engineered Soil Mix for the Purposes of Bioretention

Storm-water management strategies increasingly focus on the implementation of infiltration-based best management practices (BMPs) such as swales, bioretention basins, and rain gardens. The surface vegetation and underlying soil in these BMPs remove a variety of pollutants including heavy metals and nutrients from urban storm-water runoff. The successful attenuation of these storm-water stressors is largely influenced by the physical and chemical properties of the soils used in these systems. Controlled-condition research is being conducted using pilot-scale swales and rain gardens at U.S. EPA’s Urban Watershed Research Facility in Edison, N.J. to evaluate their performance and collect data that would help in understanding the engineering design. The first phase of this research was to evaluate and select the most appropriate soil media for use in infiltration-based BMPs for the efficient removal of heavy metals and nutrients. The objective of this laboratory incubation study was to determine how the acidic pH of an engineered infield soil media could be improved to the target pH range (5.5–7.0) suitable for heavy metals adsorption using dolomitic limestone amendments (CaCO3.MgCO3). Lime additions to the acidic infield mix resulted in neutral or slightly basic soil conditions after only 48?h of incubation. The soil response to various lime additions appeared to stabilize after more than 100?h of incubation. These results could potentially be applied to bioretention facilities to improve the sorption characteristics of the soil media.     

What's new: finding significant differences in network data streams

Monitoring and analyzing network traffic usage patterns is vital for managing IP Networks. An important problem is to provide network managers with information about changes in traffic, informing them about "what's new". Specifically, we focus on the challenge of finding significantly large differences in traffic: over time, between interfaces and between routers. We introduce the idea of a deltoid: an item that has a large difference, whether the difference is absolute, relative or variational. We present novel algorithms for finding the most significant deltoids in high-speed traffic data, and prove that they use small space, very small time per update, and are guaranteed to find significant deltoids with pre-specified accuracy. In experimental evaluation with real network traffic, our algorithms perform well and recover almost all deltoids. This is the first work to provide solutions capable of working over the data with one pass, at network traffic speeds.