单输入中立型时滞系统的镇定

本文考虑了单输人中立型时滞系统的镇定问题。利用Byrnes等人提出的中立型时滞系统的模型,我们证明:如果系统是非奇异的,则系统可镇定的充要条件是其谱可镇定。     

基于宽带毫米波工作体制的雷达目标识别方法探讨

对基于宽带毫米波工作体制的雷达目标特征获取和识别方法进行了综合分析和探讨.表明:在毫米波照射下,雷达目标可模型化为由多个散射中心组成的扩展目标;只要发射信号有足够的带宽,就可以从回波信号中获得各散射中心的空间分布、类型等特征;仿真结果说明,这种方法对高频区复杂目标的识别是有效的.     

Computerised trace method for establishing equations for dimensions and tolerances in design and manufacture

A computerised trace method has been developed for determining the relationships of assembly requirements with design dimensions and tolerances of the components in an assembly, and the relationships of design specifications and machining allowance requirements with manufactured dimensions and tolerances of the component in a process plan. This method traces from the proposed components or planned operations only the dimensions and tolerances that affect the given requirement, and therefore the equations for design or for manufacture can be established simultaneously and accurately. Hence it is possible to establish constraints for the optimisation of dimensions and tolerances for design or for manufacture.     

大港油田CNG加气站技术特点

天然气作为我国最主要能源之一，其应用领域在不断地扩展。由于天然气受管网敷设的限制。在压缩、储运等方面的技术也引起了众多企业的重视，并成为一些企业发展的战略目标。2004年大港油田依靠地域和气源的优势，建成了天津市首座CNG加气站。经过一年来的生产运行，显现出较好的经济效益和良好的发展前景。从环保性、安全性和经济性等方面阐述了CNG技术特点和发展的优势，对大港油田已建CNG加气站的主要设备、工艺流程、技术特点以及市场发展前景进行了较详尽的阐述。     

One-, two-, and three-photon pumped lasing in a novel liquid dye salt system

We report the observation of one-, two-, and three-photon pumped lasing in the same medium, a novel liquid dye salt system when excited by pulsed 0.532-, 1.06-, and /spl sim/1.49-/spl mu/m coherent radiation pulses, respectively. Since the gain medium is a liquid and not a solution, it contains a significantly higher effective dye concentration and, therefore, is highly suitable for multiphoton pumped lasing and optical power limiting applications. The lasing spectra, temporal waveforms, near- and far-field intensity distributions, and output/input efficiency were measured under the conditions of one-, two-, and three-photon pump configurations.     

基于过程能力指数的刀具寿命研究

利用Glejser检验方法拟舍出刀具磨损过程残差模型，在此基础上，计算换刀时刻的过程能力指数，并且根据企业所要求的最低过程能力指数，计算刀具的质量寿命，提出将刀具的切削寿命和质量寿命结合起来进行换刀决策的方法。     

燃煤电厂脱硫技术与脱硫泵

研究了我国能源消费的情况以及二氧化硫（SO2）排放量;介绍了现有的烟气脱硫（FGD）技术;对脱硫泵的要求,脱硫泵的结构型式以及现场应用,设计有关问题,提出了脱硫泵发展趋势,对开发、研究脱硫泵提供了有价值的方法和资料.     

3DFD Simulation of Asymmetric Wave Field by Side-wall Acoustic Tool in Open and Cased Wells

1. Introduction Side-wall acoustic logging tools, such as the Segmented Bond Tool (SBT) from Baker Atlas and the tools for open hole measurements, utilize acoustic transducers mounted on six pads to make compensated acoustic velocity and attenuation measurements which are not affected by mud weight, gas cut, fast formation effects, casing surface conditions or reasonable tool de- centralizing. Studies on the wave fields generated by these tools are very important to tool design and data int…     

A novel approach to detecting DDoS Attacks at an Early Stage

Distributed Denial-of-Service (DDoS) attacks pose a serious threat to Internet security. Most current research focuses on detection and prevention methods on the victim server or source side. To date, there has been no work on defenses using valuable information from the innocent client whose IP has been used in attacking packets. In this paper, we propose a novel cooperative system for producing warning of a DDoS attack. The system consists of a client detector and a server detector. The client detector is placed on the innocent client side and uses a Bloom filter-based detection scheme to generate accurate detection results yet consumes minimal storage and computational resources. The server detector can actively assist the warning process by sending requests to innocent hosts. Simulation results show that the cooperative technique presented in this paper can yield accurate DDoS alarms at an early stage. We theoretically show the false alarm probability of the detection scheme, which is insensitive to false alarms when using specially designed evaluation functions. This work is partially supported by HK Polyu ICRG A-PF86 and CERG Polyu 5196/04E, and by the National Natural Science Foundation of China under Grant No. 90104005.