双路输出降压型控制器可产生准确、高效和可靠的高电流轨-设计要点478

引言 LTC(R)3855能够以上佳的准确度和效率来产生高电流轨,旨在满足当今最先时的网络、电信和服务器应用极其苛刻的要求.     

A model for integrating fixed-, random-, and mixed-effects meta-analyses into structural equation modeling.

Meta-analysis and structural equation modeling (SEM) are two important statistical methods in the behavioral, social, and medical sciences. They are generally treated as two unrelated topics in the literature. The present article proposes a model to integrate fixed-, random-, and mixed-effects meta-analyses into the SEM framework. By applying an appropriate transformation on the data, studies in a meta-analysis can be analyzed as subjects in a structural equation model. This article also highlights some practical benefits of using the SEM approach to conduct a meta-analysis. Specifically, the SEM-based meta-analysis can be used to handle missing covariates, to quantify the heterogeneity of effect sizes, and to address the heterogeneity of effect sizes with mixture models. Examples are used to illustrate the equivalence between the conventional meta-analysis and the SEM-based meta-analysis. Future directions on and issues related to the SEM-based meta-analysis are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adaptive reflex autonomicity for real-time systems

It may appear that for software systems that require strict real-time behavior, the idea of incorporating self-management (and specifically concepts from Autonomic Computing) may add the burden of excessive additional functionality and overhead. However, our experience is that, not only does real-time software benefit from autonomicity, but also the Autonomic Computing initiative (like other initiatives aiming at self-management) requires the expertise of the real-time community in order to achieve its overarching vision. In particular, there are emerging classes of real-time systems for which incorporation of self-management is absolutely essential in order to implement all of the requirements of the system, and in particular the timing requirements.     

Combined crease recovery finishing and pigment printing

The combined application of crease recovery finishing (using a dimethyloldihydroxyethylene urea-based finish) and pigment printing is evaluated in this study. The use of a small amount of ammonium chloride in a combined print–finish process induces significant pigment print paste viscosity losses. However, the catalyst 2-aminoethanesulphonic acid produces negligible viscosity reduction when used in the combined print–finish process, coupled with the desired levels of finish and pigment print performance. Similar dry crease recovery, breaking load, colour strength and colour fastness properties are achieved by using 2-aminoethanesulphonic acid in the combined print–finish process relative to the conventional print–finish process.     

Effects of gas composition on asynchronous error motion in externally pressurized spindles

Stable, externally pressurized aerostatic spindles exhibit picometer-level vibration as a result of the interaction of the high-pressure working fluid and its path through a spindle's compensation features (e.g., grooves, orifices, pockets, etc.). This vibration presents a challenge as end users seek the lowest possible asynchronous error motion in manufacturing, metrology and data storage applications. This technical brief describes experimental testing to quantify this low-level vibration and its significant variation with both supply gas composition and pressure. Of the gases tested, helium and neon generate the lowest vibration while other gases including air lead to an order of magnitude higher vibration. Vibration levels with carbon dioxide and nitrous oxide are an additional order of magnitude higher. At present, the root cause of the vibration amplitude dependence on supply gas composition is unknown although kinematic viscosity and mean free path length correlate well with the results presented here.     

A theoretical framework for multiple neural network systems

Multiple neural network systems have become popular techniques for tackling complex tasks, often giving improved performance compared to single network systems. For example, modular systems can provide improvements in generalisation through task decomposition, whereas multiple classifier and regressor systems typically improve generalisation through the ensemble combination of redundant networks. Whilst there has been significant focus on understanding the theoretical properties of some of these multi-net systems, particularly ensemble systems, there has been little theoretical work on understanding the properties of the generic combination of networks, important in developing more complex systems, perhaps even those a step closer to their biological counterparts. In this article, we provide a formal framework in which the generic combination of neural networks can be described, and in which the properties of the system can be rigorously analysed. We achieve this by describing multi-net systems in terms of partially ordered sets and state transition systems. By way of example, we explore an abstract version of learning applied to a generic multi-net system that can combine an arbitrary number of networks in sequence and in parallel. By using the framework we show with a constructive proof that, under specific conditions, if it is possible to train the generic system, then training can be achieved by the abstract technique described.     

Understanding particle dynamics in erosion testers—A review of influences of particle movement on erosion test conditions

An understanding of particle dynamics is important when determining material erosive wear in any erosion tester, because particle impact conditions are primarily influenced by particle acceleration. A better understanding of particle dynamics in the testers will aid the control of erosion test conditions and therefore improve the accuracy of measurement. In this paper, particle dynamics in the two most popular erosion testers, the centrifugal erosion tester and the gas-blast erosion tester, has been discussed in detail. Mechanisms of particle acceleration in the two types of testers were explored and computational models of particle dynamics were described briefly. A review of the experimental determination of important characteristics of particle dynamics (such as particle velocity, particle trajectory, particle dispersion and particle rotation) showed how they influenced particle movement and therefore the particle impact conditions. In addition, comparison of the particle dynamics in the two types of erosion testers showed that differences of particle acceleration may lead to significantly different results at identical pre-set test conditions. It may be concluded that it is not possible to directly compare the results obtained in different types of erosion testers even under notionally identical test conditions.