Distributed Estimation Via Random Access

In this correspondence, the problem of distributed Bayesian estimation is considered in the context of a wireless sensor network. The Bayesian estimation performance is analyzed in terms of the expected Fisher information normalized by the transmission rate of the sensors. The sensors use a communication scheme known as the type-based random access (TBRA) scheme. Under a constraint on the expected transmission energy, an optimal spatio-temporal allocation scheme that maximizes the performance metric is characterized. It is shown that the performance metric is crucially dependent on the fading parameter known as the channel coherence index. For channels with low coherence indices, sensor transmissions tend to cancel each other, and there exists an optimal finite mean transmission rate that maximizes the performance metric. On the other hand, for channels with high coherence indices, there should be as many simultaneous transmissions as allowed by the network. The presence of a critical coherence index where the change from one behavior to another occurs is established.     

Reduced-Dimensional ESPRIT for Direction Finding in Monostatic MIMO Radar with Double Parallel Uniform Linear Arrays

In this paper, the issue of two-dimensional direction of arrival estimation in monostatic multiple-input–multiple-output (MIMO) radar with double parallel uniform linear arrays is studied, and an algorithm based on estimation of signal parameters via rotational invariance techniques (ESPRIT) is proposed. Through a series of reduced-dimensional transformations, the proposed algorithm has very low complexity due to the low dimension. Meanwhile, the estimation performance of the proposed algorithm is slightly improved compared to the conventional ESPRIT, especially in low signal-to-noise ratio. Furthermore, the algorithm can estimate azimuth and elevation angles without additional pair matching in monostatic MIMO radar. Error analysis of the angle estimation and Cramér–Rao bound are derived. Simulation results verify the usefulness of our algorithm.     

分数阶Fourier变换域中网络流量的自相似特性分析

通过分析网络流量数据在FrFT域的统计特性发现,实际网络流量在FrFT域满足自相似性,进一步地,针对网络流量在FrFT域的“时域”和“频域”展开,分别给出了基于改进的整体经验模态分解—去趋势波动分析（MEEMD-DFA）的Hurst指数估计法以及基于加权最小二乘回归（WLSR）的Hurst指数自适应估计法。实验结果表明,相比于现有估值算法,MEEMD-DFA法具有较高的估计精度,但计算复杂度高;而FrFT自适应估计法则具有更优的估计顽健性,且计算复杂度较低,可作为一种实时在线估计真实网络数据Hurst指数的方法。     

基于2SD315AI的静电除尘用高频高压电源研制

研制了一种新型的用于除尘系统的大功率高频高压供电电源.给出了电源主电路和控制电路的设计过程,着重研究了基于2SD315AI模块的驱动电路设计.电源的主电路由整流电路、逆变电路、高频变压器和高压整流电路组成;控制电路由主控芯片、升压调理电路、驱动电路和故障反馈电路组成.实验结果表明文中设计的控制电路及驱动电路工作稳定,性能较好能够满足大功率高频高压除尘电源的需求.     

采用可见/近红外成像光谱技术的玉米籽粒品种识别

利用地面成像光谱辐射测量系统（Field Imaging Spectrometer System,FISS）获取了5种玉米籽粒的成像光谱数据,经反射率反演、噪声去除和一阶微分处理后,运用Wilk-lambda逐步判别法进行波段选择并建立判别模型。交叉验证结果表明:（1） 平均识别精度为91.6%,除了高油115的识别精度仅有87%外,其他品种的识别精度均在90%以上;（2） 在分类方案、光谱波段数、每类样本数量不变的情况下,分类精度受类别数和类别间可分性的影响;（3） 随着入选波段数的增加模型识别精度逐步提高。因此成像光谱技术在玉米品种的识别以及质量检测方面具有重要的应用前景。     

A family of new complex number chaotic maps based image encryption algorithm

A family of new complex number chaotic maps based image encryption algorithm is proposed in the paper. A family of maps is constructed and proved to be chaotic in the complex number field, and its characteristics are analyzed. Two maps are selected from the chaotic maps family and are utilized to construct pseudorandom keystream sequence. In the proposed encryption algorithm, the pseudorandom keystream sequences are used to scramble and diffuse the plain image data and two entropy coding methods are used to reduce the correlation among the signals. Both theoretical analysis and experimental tests show that the proposed algorithm is secure and efficient.     

印刷油墨清洗剂

文章介绍了印刷油墨的组成及性能，印刷油墨清洗剂的类型、配制方法及其性能特点。并介绍了乳化型油墨清洗剂与半水基油墨清洗剂的区别和联系。     

基于多线程技术的监控系统的设计

详细介绍在32位操作系统Windows95／98下，用C Builder3．0开发基于多线程技术的监控系统的有关方法。     

YJB阜宁组油层精细识别与“假性”干层的认识

YJB阜二、阜一段油藏储层主要发育砂滩、砂坝、河道及泛滥平原等4种沉积微相类型,根据不同砂体的沉积特点及测井响应特征,利用大量的试油、测试及生产动态资料,细分沉积微相砂体类型,建立了油水层精细识别图版,弥补了常规测井资料应用的局限性。同时,结合储层压裂改造效果提出了"假性"干层的新认识,并建立了相应的测井解释图版。通过重新解释,释放了一批"假性"干层的潜力,为老油藏精细评价提供了依据。     

侧钻三分支鱼骨水平井钻完井技术

分支水平井技术已成为块状、多层系油藏开发的重要手段,辽河边台潜山区块应用该技术进行开发,取得了良好效果。为进一步扩大该技术的应用范围,将分支井技术与侧钻技术有机结合,完成了国内第一口侧钻三分支鱼骨水平井。重点介绍了AN3CH井的井身结构优化设计、开窗侧钻工艺和完井技术等方面的关键内容。该试验井的成功,积累了宝贵的实践经验,为今后类似油藏开发提供了一种高效的开发手段,具有一定推广应用价值,可供国内外相关技术人员借鉴。