802.11e EDCF信道接入机制的仿真研究

为进一步讨论EDCF(增强的分布式协调功能)数学建模的需要，对802．11DCF(分布式协调功能)和802．11e EDCF信道接入机制的性能进行了仿真分析，讨论了2种信道接人机制的差异，并探讨了EDCF提供QoS的原理，仿真结果表明，EDCF可以为无线局域网提供QoS保证，但在高优先级音频流和视频流过多的情况下，系统性能有所下降。     

碱性成纤维细胞因子在博莱霉素致肺纤维化肺血管损伤中的作用

目的探讨碱性成纤维细胞因子(bFGF)在博莱霉素(BLM)致大鼠肺纤维化肺组织中的表达及其在肺血管损伤中的作用。方法于大鼠气管内注射BLM以复制其肺纤维化模型,应用bFGF多克隆抗体按SABC法行免疫组织化学染色,定量图像分析。结果BLM组动物支气管上皮细胞胞浆内、支气管和肺小动脉肌层以及肺泡巨噬细胞胞浆内可见较多棕黄色细颗粒状bFGF阳性表达产物,显著高于对照组(P<0.05)。结论在BLM致大鼠肺纤维化过程中bFGF表达上调,提示bFGF可能参与肺间质纤维化的发病过程。     

预应力混凝土连续梁的荷载平衡法

简要介绍荷载平衡法的概念,通过对简支梁和连续梁等效荷载的分析,说明用荷载平衡方法可以简化预应力连续结构的分析和设计。     

基于双Markov链的效果评估模型研究

当前基于单Markov链的扫雷作战效果评估模型是一个理论意义大于实际的模型,如应用于实际的多Markov扫雷过程则还有相当的距离.文中从正交分解的角度,指出Markov评估模型只能得到定性评估结果.进一步提出了用于定性评估的双Markov模型,计算结果表明:在引入先验知识后,能在小样本数据条件下取得较为准确的评估结果.     

轿车车身制造尺寸质量控制界限的设定研究

针对车身尺寸小样本检测的实际情况，引入小波变换进行滤波，把车身尺寸的原始检测数据经过小波滤波后，分离出趋势项信号与波动项信号，在一定程度上弥补了小样本检测带来的误差，在此基础上对车身制造尺寸质量的控制界限进行修正，给出了应用实例。     

Experimental Study on Heat Transfer Enhancement of Natural Circulation Liquid Cooling System for Electronic Component

NomenclatureH :height of condenser above the evaporatorlevel( m)h:heightof FC- 72 filled in the testloop( m)q:heat flux based on projected surface area( W/cm2 )q CHF:critical heat flux( W/cm2 )Tc:cooling water temperature(°C)Ts:saturation temperature(°C)Tw:wall temperature(°C)ΔTsat:wall superheat( K)ΔTsub:liquid subcooling( K)W:flow rate of FC- 72 ( g/min)z:height of liquid in the downcomer( m)IntroductionDirect or indirect liquid cooling with phase-change by use of dielectric liq…     

Kinetic characteristic for a synchronal rotary compressor

The synchronal rotary compressor is si mple instructure,but it has stronger adaptability for a vari-ety of working medium,so it is a good type as aircompressor,oil pump andrefrigerationsystemcom-pressor.The geometric theory and structure charac-teristics of this mechanis m are introduced[1].Itgives the designing background for the synchronalrotary compressor.The calculational methods of arotary speed of cylinder and relative speed bet weenthe cylinder and bladed rotor are deduced in detail;the…     

沙眼衣原体感染与女性不孕的关系

目的　探讨生殖道沙眼衣原体感染与女性不孕的关系。方法　采用聚合酶链反应 (PCR)技术对 2 0 0例不孕患者及 10 0例正常生育者进行沙眼衣原体及解脲支原体 (UU)检测 ,并进行Logistic回归分析。结果　不孕组沙眼衣原体感染阳性率 (33.0 % )明显高于对照组 (10 .0 % ,P <0 .0 1)。经治疗后 ,沙眼衣原体检测转阴者妊娠率 (5 4 .90 % )明显高于未转阴者 (11.11% ,P <0 .0 5 )。同时证实沙眼衣原体感染与不孕、UU感染、宫颈糜烂相关 (P <0 .0 1)。结论　生殖道沙眼衣原体感染是引起不孕的因素之一。对不孕夫妇进行沙眼衣原体常规检查并及时治疗非常必要     

New Retrieval Method Based on Relative Entropy for Language Modeling with Different Smoothing Methods

A language model for information retrieval is built by using a query language model to generate queries and a document language model to generate documents. The documents are ranked according to the relative entropies of estimated document language models with respect to the estimated query language model. Two popular and relatively efficient smoothing methods, the Jelinek- Mercer method and the absolute discounting method, are used to smooth the document language model in estimation of the document language, A combined model composed of the feedback document language model and the collection language model is used to estimate the query model. A performacne comparison between the new retrieval method and the existing method with feedback is made, and the retrieval performances of the proposed method with the two different smoothing techniques are evaluated on three Text Retrieval Conference （TREC） data sets. Experimental results show that the method is effective and performs better than the basic language modeling approach; moreover, the method using the Jelinek-Mercer technique performs better than that using the absolute discounting technique, and the perfomance is sensitive to the smoothing peramters.     

AIS在船舶避碰中的应用

根据IMO要求，海上航行船舶将陆续安装AIS系统。如何利用AIS系统进行船舶避让，将是驾驶员首先要解决的问题。本文针对ARPA和VHF的局限性及AIS的技术特点，对AIS在船舶避碰中的应用进行了阐述。