Availability modeling of energy management systems

Energy management system (EMS) computer architectures have changed significantly over the recent past increasing the difficulty and the need for a priori assessment of system performance and dependability. The old practice based on measurements is no longer acceptable because of the flexibility accrued with the deployment of the new distributed computer-based systems. The number of “what if” questions increased since EMS systems are now implemented using multiple workstations that can be interconnected in various different ways.In this paper we show how alternative configurations can be modeled and analyzed, before proposing and purchasing any equipment, with the assistance of Markov reward models. We review the concept of Markov reward models and show how they can be applied in the availability analysis of SCADA/EMS computer systems. The paper also presents a software tool that facilitates automatic generation and solution of large Markov reward models. The input language of this modeling tool uses a variation of stochastic Petri nets called stochastic reward nets, which are also reviewed. We believe this is the first time a detailed quantitative model of a SCADA/EMS computer system is proposed and solved in the general literature.     

Buffer losses vs. deadline violations for ABR traffic in an ATM switch: A computational approach

The B‐ISDN will carry a variety of traffic types: the Variable Bit Rate traffic (VBR), of which compressed video is an example, Continuous Bit Rate traffic (CBR), of which telemetry is an example, Data traffic, and Available Bit Rate traffic (ABR) that represents aggregate data traffic with very limited guarantees on quality. Of these, VBR and CBR have timing constraints and need synchronous bandwidth; data traffic is relatively delay insensitive. In this paper, we consider the VBR, Data and ABR traffic types and obtain the cumulative distribution function (cdf) of the queueing delay experienced by a burst of ABR traffic in the output buffer of an ATM switch. The cdf is used to trade off buffer loss probabilities against deadline violation probabilities through adjusting the buffer size and (delay) deadline values. Large buffers result in low losses but queueing delays can become excessive and cause a high level of deadline violations. Both losses and violations are detrimental and an operating point must be chosen to achieve a balance. In this paper we study the nature of the trade off. We develop a stochastic Petri net model assuming periodic burst arrivals for VBR and Poisson arrival processes for the Data and ABR traffic types at the burst level, and solve the model analytically (numerically) using a decomposition approach. This decomposition, along with the inherent decomposability of the tagged customer approach for obtaining the cdf opens up a possibility of carrying out fast computations using a parallel machine for selecting the operating point each time that a call is admitted. This revised version was published online in June 2006 with corrections to the Cover Date.     

Lane Change Intent Analysis Using Robust Operators and Sparse Bayesian Learning

In this paper, we demonstrate a driver intent inference system that is based on lane positional information, vehicle parameters, and driver head motion. We present robust computer vision methods for identifying and tracking freeway lanes and driver head motion. These algorithms are then applied and evaluated on real-world data that are collected in a modular intelligent vehicle test bed. Analysis of the data for lane change intent is performed using a sparse Bayesian learning methodology. Finally, the system as a whole is evaluated using a novel metric and real-world data of vehicle parameters, lane position, and driver head motion.     

Occupant posture analysis with stereo and thermal infrared video: algorithms and experimental evaluation

Dynamic analysis of vehicle occupant posture is a key requirement in designing "smart airbag" systems. Vision-based technology could enable the use of precise information about the occupant's size, posture, and, in particular, position in making airbag-deployment decisions. Novel sensory systems and algorithms need to be developed for capture, analysis, and classification of dynamic video-based information for a new generation of safe airbags. This paper presents a systematic investigation in which stereo and thermal long-wavelength infrared video-based real-time vision systems are developed and systematically evaluated. It also includes the design of several test beds, including instrumented vehicles for systematic experimental studies for the evaluation of independent and comparative evaluation in automobiles. Results of extensive experimental trials suggest basic feasibility of stereo and thermal long-wavelength infrared video-based occupant position and posture-analysis system.     

Modeling of solidification microstructures in concentrated solutions and intermetallic systems

Most of the theoretical models for the predictions of solidification microstructure and solute segregation are based on the assumption mat the solute distribution coefficient,k, is independent of temperature. For concentrated alloys and for alloys near intermetallic compounds,k may vary significantly with temperature. A theoretical analysis which shows the necessary modifications in the theoretical models which must be made ifk varies with temperature is developed. It is shown that for phase diagrams with linear liquidus and solidus segments, many of the results derived with constantk can be used if the solute distribution coefficientk is replaced by a modified parameterk* which includesk as well as the derivative ofk with composition. The application of the model to concentrated alloys and to compositions near intermetallic phases is discussed. It is shown that the variation ink with temperature can significantly alter the composition dependence of dendritic microstructural scales and change the solute segregation profiles in solidified alloys.     

A case study of long-term RO plant operation without chemical pretreatment

Described herein is a case study of long-term reverse osmosis (RO) plant operation without applying chemical pretreatments to the feed water. This project was undertaken with the financial support from the Department of Bio-Technology, New Delhi, and the work was carried out by a research team from Central Salt and Marine Chemicals Research Institute (CSMCRI), Bhavnagar (Gujarat), India. A prototype plant with a 30,000 L/d capacity was designed, manufactured, installed and operated at the village of Mocha-Gorsar, located in the Porbandar district, to provide drinking water. The village was to be developed as a model Bio-Village where other projects related to village problems are also operated by other research institutes. Thin-film composite (TFC) membrane-based RO technology was indigenously developed by the institute for treatment of brackish water and waste water for the first time in India; it was used successfully in this plant, which gave a typical NaCl rejection of about 95%. This is a typical case study of RO plant installation where physical methods of pretreatment such as sand and micron cartridge filters were used; no chemical pretreatment of feed was employed for long-term brackish water desalination study. The idea was to avoid the usage of chemicals, which concentrate in the effluent water, might affect the environment and may not suit the village community. Plant performance during 24 months of continuous operation with respect to variable feed salinity, membrane cleaning and regenerations is discussed.     

The development of solidification microstructures in the presence of lateral constraints

The effect of a sudden change in cross section on the microstructural development has been investigated by the directional solidification technique. Experiments have been carried out in a transparent model system of succinonitrile-acetone so that the dynamical changes in the interface shapes can be monitoredin situ as the interface travels from a region of uniform cross section to a region of sharply reduced cross section. Different experimental conditions which give rise to initial steady-state planar, cellular, and dendritic interfaces have been investigated. Significant changes in microstructures have been observed as the interface approaches a sharply reduced cross section. The planar interface undergoes transitions to cellular and dendritic morphologies as the cross section is reduced, and reverse transitions are observed as the cross section is then increased gradually to its original value. An initial cellular interface is found to become dendritic as the cross section is reduced, and again it becomes cellular as the cross section is increased. When the experimental conditions are designed to give initial dendritic structures, the change in microstructure is found to occur only when the reduced cross section is of the order of primary dendrite spacing. When the reduced cross section is more than about 5 times the primary spacing, no appreciable change is observed in the dendritic array which travels across the cross-sectional change. The dynamical changes in the interface shape and the microstructural transitions that occur with the change in cross section have been examined quantitatively and discussed. Formerly with Ames Laboratory     

Cellular array morphology during directional solidification

Cellular array morphology has been examined in the shallow cell, deep cell, and cell-to-dendrite transition regime in Pb-2.2 wt pct Sb and Al-4.1 wt pct Cu alloy single-crystal samples that were directionally solidified along [100]. Statistical analysis of the cellular spacing distribution on transverse sections has been carried out using minimum spanning tree (MST), Voronoi polygons, radial distribution factor, and fast Fourier transform (FFT) techniques. The frequency distribution of the number of nearest neighbors and the MST parameters suggest that the arrangement of cells may be visualized as a hexagonal tessellation with superimposed 50 pct random noise. However, the power spectrum of the Fourier transform of the cell centers shows a diffused single-ring pattern that does not agree with the power spectrum from the hexagonal tessellation having a 50 pct superimposed random (uniformly distributed or Gaussian) noise. The radial distribution factor obtained from the cells is similar to that of liquids. An overall steady-state distribution in terms of the mean primary spacing is achieved after directional solidification of about three mushy-zone lengths. However, the process of nearest-neighbor interaction continues throughout directional solidification, as indicated by about 14 pct of the cells undergoing submerging in the shallow cell regime or by an increasing first and second nearest-neighbor ordering along the growth direction for the cells at the cell-to-dendrite transition. The nature of cell distribution in the Al-Cu alloy appears to be the same as that in the Pb-Sb. The ratio between the upper and lower limits of the primary spacing, as defined by the largest and the smallest 10 pct of the population, respectively, is constant: 1.43±0.11. It does not depend upon the solidification processing conditions.     

神经网络计算方法在煤与瓦斯突出预测中的应用

准确确定煤与瓦斯突出是对矿井安全生产十分有益的事。由于影响煤与瓦斯突出的因素很多，用传统方法很难对其进行准确预测。神经网络技术是一门在20世纪80年代中期兴起且在近年迅速发展的前沿交叉学科。它是以模拟大脑的思维方式进行计算的，比较善于处理多因素问题，因此用神经网络技术对煤与瓦斯突出进行预测是有一定的研究价值的。     

Analytical modeling of Junctionless Accumulation Mode Cylindrical Surrounding Gate MOSFET (JAM‐CSG)

This paper presents physics based analytical model for center potential, electric field and subthreshold drain current of Junctionless Accumulation Mode Cylindrical Surrounding Gate MOSFET (JAM‐CSG). The expressions are derived from Poisson's equation in cylindrical co‐ordinate system based on parabolic potential approximation (PPA). The influence of technology parameter variations such as gate length, silicon pillar diameter and oxide thickness on electrical characteristics is studied in detail. Developed analytical model results are validated through the good agreement with simulated data obtained from ATLAS 3D simulator. Copyright © 2016 John Wiley & Sons, Ltd.