Error-resilient video communications over CDMA networks with a bandwidth constraint.

We present an adaptive video transmission scheme for use in a code-division multiple-access network, which incorporates efficient bandwidth allocation among source coding, channel coding, and spreading under a fixed total bandwidth constraint. We derive the statistics of the received signal, as well as a theoretical bound on the packet drop rate at the receiver. Based on these results, a bandwidth allocation algorithm is proposed at the packet level, which incorporates the effects of both the changing channel conditions and the dynamics of the source content. Detailed simulations are done to evaluate the performance of the system, and the sensitivity of the system to estimation error is presented.     

A Heuristic Approach to the Discovery of Macro-Operators

This paper describes a heuristic approach to the discovery of useful macro-operators (macros) in problem solving. The approach has been implemented in a program, MACLEARN, that has three parts: macro-proposer, static filter, and dynamic filter. Learning occurs during problem solving, so that performance improves in the course of a single problem trial. Primitive operators and macros are both represented within a uniform representational framework that is closed under composition. This means that new macros can be defined in terms of others, which leads to a definitional hierarchy. The representation also supports the transfer of macros to related problems. MACLEARN is embedded in a supporting system that carries out best-first search. Experiments in macro learning were conducted for two classes of problems: peg solitaire (generalized Hi-Q puzzle), and tile sliding (generalized Fifteen puzzle). The results indicate that MACLEARN'S filtering heuristics all improve search performance, sometimes dramatically. When the system was given practice on simpler training problems, it learned a set of macros that led to successful solutions of several much harder problems.     

电能变换领域中随机脉宽调制技术研究概况及展望

相较于传统的脉宽调制技术,随机脉宽调制具备有效的谐波频谱分散能力,从而实现机电负载噪声的削弱。随机脉宽调制技术包括起步的随机开关调制、后续的随机脉冲位置与随机开关频率等3个基本方法。随着电力电子技术的整体发展,随机脉宽调制已从传统的载波调制逐渐拓展到空间矢量调制之中,应用范围日趋广泛,谐波频谱分散与功率谱峰值抑制的效果不断提升。同时,新的优化方案不断被提出,对谐波频谱及功率谱的分散效果亦在不断提高。梳理了随机脉宽调制的研究历程,总结了数种典型的随机脉宽调制的基本原理,并对未来随机脉宽调制的研究方向作出展望,为随机脉宽调制技术的深入研究提供参考。     

镍基单晶合金枝晶典型区域相成分最优化测算法

建立了用于测算镍基单晶高温合金枝晶典型区域相成分的最优化数学模型.根据电子探针对枝晶典型区域成分的测定结果,运用BFGS拟Newton法及CONSTR约束优化算法,可以计算枝晶各典型区域中γ和γ＇相成分.以镍基单晶合金CMSX-2和CMSX-4为对象,对优化测算结果进行了分析,证实了该方法的可行性.     

A limit set stabilization by means of the Port Hamiltonian system approach

A solution to the stabilization problem of a compact set by means of the Interconnection and Damping Assignment Passivity‐Based Control methodology, for an affine nonlinear system, was introduced. To this end, we expressed the closed‐loop system as a Port Hamiltonian system, having the property of almost all their trajectories asymptotically converge to a convenient limit set, except for a set of measure zero. It was carried out by solving a partial differential equation (PDE) or single matching condition, which allows the desired energy level or limit set E to be shaped explicitly. The control strategy was tested using the magnetic beam balance system and the pendulum actuated by a direct current motor (DC‐motor), having obtained satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.     

Water–energy–food nexus in a transboundary context: the Euphrates–Tigris river basin as a case study

The interlinkage between water, energy and food security and its transboundary relevance is becoming increasingly important. The paper analyses the evolution of transboundary water resources management in the Euphrates–Tigris basin with specific reference to interlinkages between water, food and energy policies at national and transboundary levels, and it explores how the policy shifts at the highest decision-making level have served to produce synergies for cooperation among the riparians or vice versa.     

Boosted Bayesian network classifiers

The use of Bayesian networks for classification problems has received a significant amount of recent attention. Although computationally efficient, the standard maximum likelihood learning method tends to be suboptimal due to the mismatch between its optimization criteria (data likelihood) and the actual goal of classification (label prediction accuracy). Recent approaches to optimizing classification performance during parameter or structure learning show promise, but lack the favorable computational properties of maximum likelihood learning. In this paper we present boosted Bayesian network classifiers, a framework to combine discriminative data-weighting with generative training of intermediate models. We show that boosted Bayesian network classifiers encompass the basic generative models in isolation, but improve their classification performance when the model structure is suboptimal. We also demonstrate that structure learning is beneficial in the construction of boosted Bayesian network classifiers. On a large suite of benchmark data-sets, this approach outperforms generative graphical models such as naive Bayes and TAN in classification accuracy. Boosted Bayesian network classifiers have comparable or better performance in comparison to other discriminatively trained graphical models including ELR and BNC. Furthermore, boosted Bayesian networks require significantly less training time than the ELR and BNC algorithms.     

Influence of partial replacement of NaCl with KCl on lipid fraction of dry fermented sausages inoculated with a mixture of Lactobacillus plantarum and Staphylococcus carnosus

The effect of partial replacement of NaCl (3% NaCl) with KCl (1.5% NaCl and 1% KCl) on the lipid fraction of dry fermented sausages inoculated with Lactobacillus plantarum and Staphylococcus carnosus as starter culture was analysed. The reduction in salt concentration did not affect the Micrococcaceae count. A positive effect on the intensity of lipolytic activity was observed as a consequence of the decrease in salt level. There was no decrease in the oxidative processes. The higher amounts of volatile fatty acids found suggest that the tested modification enhances some of their mechanisms of synthesis.     

红外反射式光学系统光机结构设计与分析

为实现红外双波段共孔径光学系统,设计出一种采用大孔径、无焦反射式光学系统,并详细介绍该系统结构.中波和长波MTF值在25线对下均大于0.3.考虑到该光学系统野外使用时复杂的运输环境,利用有限元法对简化后的卡塞格林式望远系统进行低阶振动特性和模态特性分析.通过比较2种材料的模态分析计算结果,最终选取铝合金为金属材料,保证1阶固有频率大于50 Hz,满足野外运输条件,说明该系统结构合理可行.