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221.
针对现代通信网业务量在幅度和时间尺度上的突发特性,提出了一种综合稳定分布和高斯自相似分布的模型,即基于α-Stable自相似过程的模型来同时反映业务量的两种突发特性,并通过仿真证明了它非常适合于现代通信网的业务量,该模型可以根据不同的性能需要来产生相应的模拟业务量,从而对网络业务量性能相关的研究有一定的实用价值。 相似文献
222.
鞋样设计CAD系统中需要检测直线 ,而检测直线的方法多种多样 ,选用Hough直线检测法的主要原因是Hough直线检测法受噪声和断线的影响较小 .利用各种仿真图对该算法进行测试 ,结果证明Hough直线检测法切实具有极佳的抗干扰能力 ,可达到较高的准确度 .此外 ,Hough直线检测法不仅可应用于鞋样设计CAD系统中 ,它在服装样片等许多CAD设计系统中同样具有实际应用价值 相似文献
223.
ZHAO Zhibin YAO Lan YANG Xiaochun LI Binyang YU Ge 《武汉大学学报:自然科学英文版》2006,11(5):1383-1388
In this paper we propose a Filter-based Uniform Algorithm (FbUA) for optimizing top-κ query in distributed networks, which has been a topic of much recent interest. The basic idea of FhUA is to set a filter at each node to pre vent it from sending out the data with little chance to contrib ute to the top-κ result. FbUA can gain exact answers to top-κ query through two phrases of round trip communications between query station and participant nodes. The experiment results show that FbUA reduces network bandwidth consumption dramatically. 相似文献
224.
本文运用损伤力学及可靠性方法,分析疲劳循环中防爆膜爆破压力的变化规律,给出安全寿命的计算方法及算图。通过疲劳断口的电镜扫描试验,证明防爆膜的疲劳破坏是由存在于金属内部的微裂纹和杂质所引起。 相似文献
225.
226.
介绍了分解协调控制原理在油泵实验台多功能仪中的具体实现,设计了提取串行同步数据的电路,分析了其工作原理及应用。 相似文献
227.
Duan Jinqing Zhang Xinian Liu Hongbin Liu Zheng Liu Guozhen Lu Hongrnin Liu Junxin Ge Rili 《中国工程科学》2006,4(2):187-191
Study Objective : To evaluate the treatment effect of HAPE with HBO in situ at an extreme altitude of 4636 m. To investigate the relationship between pulmonary hypertension (PH) and HAPE. To emphasize the importance of the treatment in situ. Methods: The 32 patients from the plateau of 4636 - 5130 m (the barometric pressure: 57.41 - 53.28 kPa/431.6 - 400.6 mmHg(1 mmHg = 133.3224 Pa), the partial pressure of oxygen: 12.0 - 11.6 kPa/90.0 - 87.0 mmHg) were treated in situ of 4636 m altitude with HBO. Before and after the treatment, the clinical symptoms / signs, radiographic evidence, SaO2, and MPAP were compared. Results: The clinical symptoms/signs, and all the targets of the patients were improved dramatically (p 〈 0.001). Conclusions: Treating HAPE with HBO is the most effective method among various therapies in situ at an extreme altitude. The pulmonary -artery pressure was significantly decreased. All eases showed improved immediately. Among the subjects, 11 eases (34.3 %) were cured at once. The therapy made it possible for patients to get further treatment at a lower altitude area with prospective good results. We suggested that treating HAPE with HBO should be the first choice in situ. There must be PH in the patients of HAPE, but the reverse is not the true. The PH is a mechanism of normal compensation of the body exposing in the hypoxie environment. It is very necessary for us to explore the threshold of PH when a HAPE happens. 相似文献
228.
综合多种健美操教学方法,分析其优劣,提出在健美操教学中应当根据教学目的、内容与教学对象,适时调整教学方法,以发挥每种教学方法的优势,提高教学效果. 相似文献
229.
Jing Li XiaoMan Liu YueTong Ji ZhenHui Qi Yan Ge JiaYun Xu JunQiu Liu GuiMin Luo JiaCong Shen 《科学通报(英文版)》2008,53(16):2454-2461
Glutathione peroxidase (GPx, EC1.11.1.9), an important anti-oxidative selenoenzyme, can catalyze the reduction of harmful hydroperoxides with concomitant glutathione, thereby protecting cells and other biological issues against oxidative damage. It captures considerable interest in redesign of its function for either the mechanism study or the pharmacological development as an antioxidant. In order to develop a general strategy for specifically targeting and operating selenium in active sites of enzymes, the catalytically essential residue selenocysteine (Sec) was first successfully bioincorporated into the catalytic center of subtilisin by using an auxotrophic expression system. The studies of the catalytic activity and the steady-state kinetics demonstrated that selenosubtilisin is an excellent GPx-like biocatalyst. In comparison with the chemically modified method, biosynthesis exhibits obvious advantages: Sec could be site-directly incorporated into active sites of enzymes to overcome the non-specificity generated by chemical modification. This study provides an important strategy for specifically targeting and operating selenium in the active site of an enzyme. 相似文献
230.
Ge Changchun Xia Yttanluo Chen Limin Laboratory of Special Ceramics Powder Metallurgy 《北京科技大学学报》1991,(Z2)
Si3N4 ceramics with AZ-type non-toxic, non-oxide additives canbe highly densified. In this work densification behavior and mechanism ofSi3N4 with AZ-type additives were investigated. 相似文献