Editor’s note

正Because modern communication networks are expected to deliver increasingly high data rates at a decreasing cost per bit,the spectral efficiency of communication systems must be further improved to facilitate emerging ubiquitous services.Furthermore,because future communication networks will comprise a large     

Survivability-oriented optimal node density for randomly deployed wireless sensor networks

The survivability is usually critical for wireless sensor networks,which are often deployed in the unattended harsh environment.Lots of technical schemes to improve the survivability depend on the redundant resources of the sensor networks.The amount of resources is usually determined by the node density during the deployment phase.For the random deployment and random node failures,the quantitative relation between the survivability and the node density is studied.Based on the conditional survivability,the node density to meet the required survivability level is presented.Finally,the survivability for unpredictable failures and the optimal node density to maximize the price–performance ratio are also discussed.     

HTTP-SoLDiER: An HTTP-flooding attack detection scheme with the large deviation principle

HTTP-flooding attack is a much stealthier distributed denial of service （DDoS） attack, challenging the survivability of the web services seriously. Observing the web access behavior, we find that the surfing preference of normal users is much more consistent with the webpage popularity than that of malicious users. Based on this observation, this paper proposes a novel detection scheme for HTTP-flooding （HTTP-SoLDiER）. Specifically, HTTP-SoLDiER first quantifies the consistency between web users surfing preference and the web- page popularity with large-deviation principle. Then HTTP-SoLDiER distinguishes the malicious users from normal ones according to the large-deviation probability. In practice, the webpage popularity plays a key role in attack detection of HTTP-SoLDiER. Due to the never-ending updating of the webpage content and the disturbance induced by attackers, the webpage popularity often varies over time. Thus, it is critical for HTTP-SoLDiER to dynamically update the webpage popularity. We design a reversible exponentially weighted moving average （EWMA） algorithm to solve the problem. Finally, we evaluate the effectiveness of this scheme in terms of true positive （TF） and false positive （FP） probabilities with NS-3 simulations. The simulation results show that HTTP-SoLDiER can detect all random HTTP-flooding attackers and most of the perfect-knowledge HTTP-flooding attackers at little false positive.     

改性环氧带锈涂料的研究

研究了以改性环氧树脂和聚乙烯醇缩丁醛为基料的钢铁带锈涂料 ,通过对成膜物质、转化剂、渗透剂、颜料等的研究 ,得到了集稳定、转化、渗透为一体的多功能涂料。经过实验测试 ,该涂料的各项性能指标均达到了设计要求 ,并且本工艺方案简单易行、省时高效 ,具有较高的实用价值。     

从481—2B型废催化剂中回收钼工艺述评

钼酸铵是一种主要的化工原料，本文对从工业生产的废催化剂中回收钼的工艺进行了比较系统的概括，对各种工艺进行了比较，并给出了最佳的工艺条件。     

A 6-bit 2 GS/s ADC in 65 nm CMOS

A 6-bit 2 GS/s ADC was implemented using a 65 nm digital CMOS technology.The design is based on a single-channel flash ADC architecture,and utilizes interpolating and averaging techniques.A two-stage CML-CMOS high-speed hybrid comparator is designed for optimal speed and power performance.The total power consumption of the converter is 52 mW and the area is 0.24 mm2.The ADC achieves 42.5 dB SFDR and5.2 bit ENOB at input frequency of 123 MHz,and at Nyquist frequency 37.67 dB SFDR and 4.9 bit ENOB.     

改造医院信息系统加强医院控费管理

通过对各检查科室程序和HIS系统部分程序修改,只有交费或记账的患者才能打印报告,从而使得漏费控制从"事后控制"转变为"事前控制",为医院创造可观的经济效益。同时实现了两者无缝联接,达到信息共享。     

基于Windows内核进程监控机制的研究与实现

互联网技术的不断发展对信息系统的安全提出了更高的要求,需要对系统提供更多方面的防护机制,而系统进程则是其中防范的一个方面。本文在Windows内核驱动程序理解的基础上,对系统进程监控技术进行了深入研究,采用事件触发的机制和技术,实现了对系统进程实时可靠的监控。     

浅谈加强技术改造的适时与必要

分析了我国技术比较落后、资金相对紧张的现状，指出必须提高技术改造投资在固定资产投资中的比重，加大技术改造的力度。     

Crystallization behavior,mechanical properties,and environmental biodegradability of poly(β‐hydroxybutyrate)/cellulose acetate butyrate blends

The miscibility, crystallization behavior, tensile properties, and environmental biodegradability of poly(β‐hydroxybutyrate) (PHB)/cellulose acetate butyrate (CAB) blends were studied with differential scanning calorimetry, scanning electron microscopy, wide‐angle X‐ray diffraction, and polarizing optical microscopy. The results indicated that PHB and CAB were miscible in the melt state. With an increase in the CAB content, the degree of crystallinity and melting temperature of the PHB phase decreased, and this broadened the narrow processability window of PHB. As the elongation at break increased from 2.2 to 7.3%, the toughness and ductility of PHB improved. From the degradation test, it could be concluded that degradation occurred gradually from the surface to the inside and that the degradation rate could be adjusted by the addition of the CAB content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2116–2122, 2003