发射区硼掺杂浓度对横向PNP晶体管高低剂量率辐射损伤的影响

本文研究了发射区重硼掺杂和轻硼掺杂横向PNP晶体管的高低剂量率辐照损伤特性。实验结果表明,随总剂量的增加,晶体管基极电流增大,电流增益下降,且轻掺杂PNP晶体管的退化更为严重。文中讨论了辐照感生缺陷在发射区重掺杂和轻掺杂晶体管退化中的作用,特别是氧化物正电荷的双重作用。最后,文章详细论述了高低剂量率辐照下,重掺杂PNP晶体管集电极电流IC的辐照响应。     

The short of it: Abbreviating the temporal discounting procedure.

A typical temporal discounting procedure determines the present, subjective value (indifference point) of a delayed outcome at 5 to 8 different delays to that outcome. These indifference points are used to determine a single index of discounting called a discounting rate. One concern that remains in the collection of this data is the high number of trials or choices, resulting in participant fatigue or other factors that may affect the validity of the data. In this report, we propose an abbreviated alternative to the more comprehensive and time-consuming discounting procedure. Specifically, we propose that fewer indifference points can be used to determine statistically equivalent discount rates with no loss in data sensitivity. We reanalyzed temporal discounting data obtained with 7 indifference points, and estimated discount rates from all combinations of 2, 3, and 4 of the 7 indifference points. Results indicate that valid and sensitive discounting indices can be obtained with fewer indifference points, and the most appropriate sets of indifference points are highlighted. The proposed abbreviated procedure is likely to be particularly useful when time constraints or participant fatigue is a concern as well as in repeated-measures contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A review of the IEA/NEA Projected Costs of Electricity – 2015 edition

The IEA/NEA recently issued their eighth edition of the Study on the “Projected Costs of Generating Electricity” – 2015 edition. The Study is mainly concerned with calculating the levelised cost of electricity (LCOE). The LCOE calculations are based on a levelised average life time cost approach using the discounted cash flow (DCF) method. The analysis was this year, and for the first time, performed using three discount rates (3%, 7%, and 10%). The LCOE can serve as a tool for calculating the cost of different generation technologies. However the Study's usefulness is affected by its narrow base of a limited set of countries that are not necessarily representative. It ignored the negative role of subsidies and did not provide a methodology for selective application of the discount rates and costing of carbon. The global power generation scene is changing. Generation growth in OECD countries has become very limited; simultaneously there is rapid growth of varying renewables (VRE) generation which needs special criteria for assessing its system cost. All this demands a rethinking of the application and usefulness of the LCOE in future generation planning.     

First time home buyers in metropolitan Perth 1979 – 1984

Abstract

Since 1979 interest rates on housing loans have risen sharply affecting the ability of many households to buy their first home. This article documents the changes in the socio-economic profiles of first home buyers using building society funds in metropolitan Perth between 1979 and 1984.

It also comments on how building societies have reacted to changes in the financial market which have made housing loans from savings Banks more attractive to 1st home buyers.

The article concludes by looking at Govt. assistance to 1st home buyers in terms of the concept of neutrality.     

Investigations into the correlation of component failure rates to system supply availability in asset management methods

Liberalization has increased economic pressure on network operators, urging them to compromise between cost savings and supply reliability. In this context, the detailed and quantitative evaluation of supply reliability is gaining ever more importance—especially its application in comprehensive asset management methods. However, the large number of components especially in medium voltage distribution networks leads to high computation times for such probabilistic reliability analyses. A recent research project deals with investigations into a forecast of system supply reliability performance following a simplified methodology. Developing different forecasting methods, also several aspects of significant importance for the calculation of supply reliability in MV distribution systems in general were identified. Especially for electrical networks of a certain size, the overlapping of independent single failures, as well as complex failures play an important role. This paper presents the background of the reliability centered asset management approach as well as the general idea and different approaches to the forecasting methods in theory briefly. Following, the application on two different example networks demonstrates the approaches and the achieved results, and reveals also the relevance of overlapping and complex failures in these results.     

Effects of gage length, loading rates, and damage on the strength of PPTA fibers

Axial tension and transverse compression experiments on single fibers were performed to investigate the mechanical behavior of three high-performance fibers (Kevlar^®, Kevlar^® 129, and Twaron^®) with diameters in the order of 9-12 μm. The single fibers were manufactured from 1998 through 2008. A miniaturized tensile Kolsky bar was used to determine the tensile response of PPTA single fibers at a high strain rate. Gage length and strain rate were found to have minimum effects on the tensile strength of PPTA single fibers. Manufacturing time over a decade was found to have negligible effects on the tensile strength of the fibers. Initial transverse compression on the fibers reduces their ultimate tensile strengths. A high resolution scanning electron microscope (SEM) was also used to examine the fracture modes of transversely deformed fibers. Different types of fracture morphology were observed.     

Time-varying discrete-time linear systems with bounded rates of variation: Stability analysis and control design

This paper investigates the problems of robust stability analysis and state feedback control design for discrete-time linear systems with time-varying parameters. It is assumed that the time-varying parameters lie inside a polytopic domain and have known bounds on their rate of variation. A convex model is proposed to represent the parameters and their variations as a polytope and linear matrix inequality relaxations that take into account the bounds on the rates of parameter variations are proposed. A feasible solution provides a parameter-dependent Lyapunov function with polynomial dependence on the parameters assuring the robust stability of this class of systems. Extensions to deal with robust control design as well as gain-scheduling by state feedback are also provided in terms of linear matrix inequalities. Numerical examples illustrate the results.     

An assessment of the skid resistance effect on traffic safety under wet-pavement conditions

Pavement-tire friction provides the grip that is required for maintaining vehicle control and for stopping in emergency situations. Statistically significant negative correlations of skid resistance values and wet-pavement accident rates have been found in previous research. Skid resistance measured with SCRIM and crash data from over 1750 km of two-lane rural roads in the Spanish National Road System were analyzed to determine the influence of pavement conditions on safety and to assess the effects of improving pavement friction on safety. Both wet- and dry-pavement crash rates presented a decreasing trend as skid resistance values increased. Thresholds in SCRIM coefficient values associated with significant decreases in wet-pavement crash rates were determined. Pavement friction improvement schemes were found to yield significant reductions in wet-pavement crash rates averaging 68%. The results confirm the importance of maintaining adequate levels of pavement friction to safeguard traffic safety as well as the potential of pavement friction improvement schemes to achieve significant crash reductions.     

Modeling Federal Funds rates: a comparison of four methodologies

Monthly Federal Fund interest rate values, set by the Federal Open Market Committee, have been the subject of much speculation prior to the announcement of their new values each period. In this study we use four competing methodologies to model and forecast the behavior of these short term Federal Fund interest rates. These methodologies are: time series, Taylor, econometric and neural network. The time series forecasts use only past values of Federal Funds rates. The celebrated Taylor rule methodology theorizes that the Federal Fund rate values are influenced solely by deviations from a desired level of inflation and from potential output. The econometric and neural network models have inputs used by both the time series and Taylor rule. Using monthly data from 1958 to the end of 2005 we distinguish between sample and out-of-sample sets to train, evaluate, and compare the models’ effectiveness. Our results indicate that the econometric modeling performs better than the other approaches when the data are divided into two sets of pre-Greenspan and Greenspan periods. However, when the data sample is divided into three groups of low, medium and high Federal Funds, the neural network approach does best. An earlier version was presented at the 2007 International Joint Conference on Neural Networks in Orlando. We are thankful to the Larry Medsker, regional editor of Neural Computing and Applications, and to two anonymous referees for very insightful comments that helped us improve the final version.     

湿表面换热器的线性理论和简化计算方法

湿表面传热的数学描述和求解比干表面要复杂得多，但在应用了线性饱和线的简化理论，并引入了温表面温度、湿态放热系数和湿态比热等概念后，得到了与于表面换热器微分方程类似的形式，从而看出完全可以用干表面换热器的计算方法近似计算湿表面换热器的传热性能。