一种改进的WSN成簇算法

从保证无线传感器网络(WSN)感知覆盖性能角度出发,分析节点剩余能量、重叠感知覆盖率与簇头选择的关系,改进LEACH协议中簇头阈值选择前的信息采集过程,提出一种适用于高密度随机部署的WSN成簇算法。实验结果表明,该算法可有效保持网络感知覆盖率,从而延长网络寿命。     

基于混沌级联的语音频域实时加密系统

针对现有语音实时保密通信系统中系统空载密钥泄漏现象导致容易遭受基于自适应同步控制方法攻击的问题,采用混沌级联对语音频域进行实时加、解密。该方案实现零密钥泄漏,有效抵御了基于自适应同步控制方法的攻击。系统测试分析结果表明,该方案是有效、安全的,优于基于单组混沌系统对时域的加密方法。     

基于误差补偿的复杂场景下背景建模方法

在基于子空间学习的背景建模方法中,利用背景信息对前景误差进行补偿有助于建立准确的背景模型.然而,当动态背景（摇曳的树枝、波动的水面等）和复杂前景等干扰因素存在时,补偿过程的准确性和稳定性会受到一定的影响.针对这些问题,本文提出了一种基于误差补偿的增量子空间背景建模方法.该方法可以实现复杂场景下的背景建模.首先,本文在误差补偿的过程中考虑了前景的空间连续性约束,在补偿前景信息的同时减少了动态背景的干扰,提高了背景建模的准确性.其次,本文将误差估计过程归结为一个凸优化问题,并根据不同的应用场合设计了相应的精确求解算法和快速求解方法.再次,本文设计了一种基于Alpha通道的误差补偿策略,提高了算法对复杂前景的抗干扰能力.最后,本文构建了不依赖于子空间模型的背景模板,减少了由前景信息反馈引起的背景更新失效,提高了算法的鲁棒性.多项对比实验表明,本文算法在干扰因素存在的情况下仍然可以实现对背景的准确建模,表现出较强的抗扰性和鲁棒性.     

工程火警监测的计算机自动处理

阐述了采用红外摄象及计算机自动处理技术,对工程火警进行监测。采用图值,面积、形状智能识别和实时行程编码技术,系统的识别可靠性大为提高。     

Reducing the overhead of dynamic compilation

The execution model for mobile, dynamically‐linked, object‐oriented programs has evolved from fast interpretation to a mix of interpreted and dynamically compiled execution. The primary motivation for dynamic compilation is that compiled code executes significantly faster than interpreted code. However, dynamic compilation, which is performed while the application is running, introduces execution delay. In this paper we present two dynamic compilation techniques that enable high performance execution while reducing the effect of this compilation overhead. These techniques can be classified as (1) decreasing the amount of compilation performed, and (2) overlapping compilation with execution. We first present and evaluate lazy compilation, an approach used in most dynamic compilation systems in which individual methods are compiled on‐demand upon their first invocation. This is in contrast to eager compilation, in which all methods in a class are compiled when a new class is loaded. In this work, we describe our experience with eager compilation, as well as the implementation and transition to lazy compilation. We empirically detail the effectiveness of this decision. Our experimental results using the SpecJVM Java benchmarks and the Jalapeño JVM show that, compared to eager compilation, lazy compilation results in 57% fewer methods being compiled and reductions in total time of 14 to 26%. Total time in this context is compilation plus execution time. Next, we present profile‐driven, background compilation, a technique that augments lazy compilation by using idle cycles in multiprocessor systems to overlap compilation with application execution. With this approach, compilation occurs on a thread separate from that of application threads so as to reduce intermittent, and possibly substantial, delay in execution. Profile information is used to prioritize methods as candidates for background compilation. Methods are compiled according to this priority scheme so that performance‐critical methods are invoked using optimized code as soon as possible. Our results indicate that background compilation can achieve the performance of off‐line compiled applications and masks almost all compilation overhead. We show significant reductions in total time of 14 to 71% over lazy compilation. Copyright © 2001 John Wiley & Sons, Ltd.     

不规则柱状节理玄武岩变形参数反分析研究

在力学分析时,柱状节理玄武岩可视为玄武岩刚性材料与节理面接触材料的复合型二元介质,其物理力学特性主要由节理面控制。同时,节理面法向刚度K n和切向刚度K s选取标准直接影响到等效岩体变形模量。结合白鹤滩水电站坝址区柱状节理玄武岩原位变形载荷试验,基于广义回归神经网络(GRNN)及三维离散元模拟(3DEC)方法进行节理变形参数的反分析,分析计算结果与实测结果吻合较好。     

黄河中游府谷至吴堡未控区降雨径流关系初探

通过三种方法分析了2012年7月下旬发生在黄河中游府谷—吴堡区间两次洪水的来源与组成,并与多场历史相似洪水对比,结果表明:该区间未控区为典型超渗产流区,其洪峰流量、径流总量与降雨量、降雨强度有密切关系;未控区是吴堡站洪水的主要来源区之一,对洪水预报精度和预见期有较大影响。初步建立了该未控区降雨径流关系。     

秦巴地区生态分区的初步研究

秦巴地区在我国生态保护中具有重要的战略意义,其生态分区可为生态系统管理和自然资源可持续利用提供科学依据。针对秦巴地区存在的水污染、水土流失和地质灾害等生态环境问题,以该地区的地形特征、植被状况、气候条件和人类活动因子等作为生态分区指标,并采用主成分分析的定量分析方法,建立了指标体系。利用GIS技术中的空间分析和叠加分析技术,将秦巴地区划分成3个一级分区、5个二级分区和11个三级分区。依据分区结果,对各个分区的生态特征及问题进行了分析,提出了生态环境保护建议。     

HNST500环保型连续式逆顺流稻谷保质干燥机的研发

首次设计了HNST500环保型连续式逆顺流高水分稻谷保质干燥机,该机采用4级逆流干燥、4级顺流干燥(共计8级干燥),4级缓苏,1级逆流冷却、1级顺流冷却(共计2级冷却),逆流和顺流交替进行,每一级逆流和顺流干燥后设置一级缓苏,干燥缓苏级数随降水幅度的增大而增加.通过生产试验证实了该机具有热效率高、节能明显、干燥后品质好、环保、无污染、连续生产一次性降至安全水分等特点.     

我国收入差距扩大的因素分析与政策建议

收入差距问题已经成为当前社会关注的热点问题之一,严重影响到社会的稳定和国家的长治久安。为此,针对我国收入差距的现状、形成收入差距的因素进行深层次分析,并提出推进市场化改革、缩小人力资本差异、完善税收制度等解决思路,以期对缩小我国收入差距有所启迪。