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21.
本文比较全面地考虑了钢筋混凝土梁板结构实际设计时的全部必要约束,给出了一套(单跨矩形和T形梁、单向板、按弹性理论计算的双向板和矩形等截面连续梁)简单实用的近优化设计的解析公式,为编制其优化设计的实用程序和图表提供了根据. 相似文献
22.
J Lamoril C Andant C Bogard H Puy L Gouya JM Pawlotsky V Da Silva JC Soulé JC Deybach Y Nordmann 《Canadian Metallurgical Quarterly》1998,27(3):848-852
From 1995 to 1997, we prospectively evaluated the prevalence of hepatitis C virus (HCV) RNA in 124 patients with porphyria cutanea tarda (PCT) from Northern France (83 sporadic and 41 familial PCT). Serum samples were analyzed for ferritin, transaminases, HCV antibodies, and HCV RNA. In addition, genotyping of HCV and searches for HCV infection risk factors (blood transfusion, iv drug abuse, and surgical intervention) were performed. Twenty-six of 124 patients (21%; 95% CI: 13.9-28) were positive for serum HCV antibodies. All of them were also positive for HCV RNA. The prevalence of HCV infection was higher in the sporadic PCT group (26.5%, 22 out of 83) than in the familial PCT group (9.7%, 4 out of 41). Risk factors for hepatitis C infection were found to be significantly increased in the HCV-positive group when compared with the HCV-negative PCT group. In all HCV-positive patients with a risk factor, the suspected date of exposure to the virus always preceded the clinical onset of PCT. The HCV genotype pattern in PCT patients was similar to that observed in nonporphyric HCV patients in western European countries. Serum ferritin level was increased in both HCV-positive and HCV-negative porphyric patients. Transaminase levels were significantly higher in HCV-infected PCT patients. Sixty-seven out of 124 patients were retrospectively studied for hepatitis G virus (HGV) infection. Six of these 67 patients (8.9%; 95% CI: 2.1-15.8) were positive for HGV RNA. None of the six HGV-infected patients were positive for HCV RNA. The HGV-infected patients did not differ statistically from those without HGV infection with regard to age, ferritin, transaminase levels, and PCT treatment. These results support the view that sporadic cases of HGV infection may occur frequently. This study of a large cohort of HCV and PCT patients further documents an increasing gradient in HCV prevalence from northern to southern Europe, and shows that HCV infection acts as a triggering factor of PCT. Finally, the HGV prevalence found in the PCT patients was comparable with that found in French blood donors, suggesting that HGV is not a PCT triggering factor. 相似文献
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Kyeongho Lee Yeshik Shin Sungjoon Kim Deog-Kyoon Jeong Kim G. Kim B. Da Costa V. 《Solid-State Circuits, IEEE Journal of》1998,33(5):816-823
In a high-resolution flat panel system, a conventional interface that directly connects a liquid crystal display (LCD) controller to a flat panel cannot overcome the problems of excess EMI (electromagnetic interference) and power caused by full-swing transmission signals in parallel lines. This paper presents a high-speed digital video interface system implemented with a low-cost standard CMOS (complimentary metal-oxide-semiconductor) technology that can mitigate EMI and power problems in high-resolution flat panel display systems. The combined architecture of the high-speed, small number of parallel lines and low-voltage swing serial interface can support resolutions from VGA (640×480 pixels) up to XGA (1024×768 pixels) with significant power improvement and drastic EMI reduction. To support high-speed, low-voltage swing signaling and overcome channel-to-channel skew problems, a robust data recovery system is required. The proposed digital phase-locked loop enables robust skew-insensitive data recovery of up to 1.04 GBd 相似文献
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The combination of the techniques of expert systems and neural networks has the potential of producing more powerful systems, for example, expert systems able to learn from experience. In this paper, we address the combinatorial neural model (CNM), a kind of fuzzy neural network able to accommodate in a simple framework the highly desirable property of incremental learning, as well as the usual capabilities of expert systems. We show how an interval-based representation for membership grades makes CNM capable of reasoning with several types of uncertainty: vagueness, ignorance, and relevance commonly found in practical applications. In addition, we show how basic functions of expert systems such as inference, inquiry, censorship of input information, and explanation may be implemented. We also report experimental results of the application of CNM to the problem of deforestation monitoring of the Amazon region using satellite images 相似文献
25.
一种铁氧体移相驱动器专用集成电路 总被引:1,自引:1,他引:0
介绍了SA018铁氧体移相驱动器专用集成电路的工作原理,电路设计和实验结果。该电路的内部电路设计有双路激励驱动器,放大器,积分器和双路高速比较器等功能单元。将铁氧体移相器的激励驱动器和相位控制器融于一体,大大减少了铁氧体移相器的外围设计。 相似文献
26.
络合沉淀法制备BaTiO_3超细粉末 总被引:4,自引:1,他引:3
在分析BaTiO_3前驱体形成机理的基础上,提出了以草酸作为络合剂,用络合沉淀法制备超细BaTiO_3新工艺。用化学分析法测定产物Ba/Ti比,用XRD、TEM、BI-90激光散射粒度仪对产物的晶型、粒度及形貌进行表征。结果表明:采用该法合成的前驱体,微观组分确定,粒径小,粒度分布窄,近似球形,煅烧后为高纯超细BaTiO_3粉末。 相似文献
27.
采用空心光纤自诊断、自修复智能结构的研究 总被引:17,自引:1,他引:16
为了对复合材料结构的损伤进行自修复,提出了利用空心光纤实现智能复合材料结构中难度较大的自修复功能,对其中的一些关键技术进行了初步的研究。利用空心光纤作为输送修复结构胶液的通道,当结构的关键部位出现损伤时,内含胶液的空心光纤网络可以检测出结构损伤的位置,并输出胶液对损伤进行修复,从而实现对复合材料结构损伤的自诊断及自修复功能。 相似文献
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