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941.
Using the finite element method (FEM) and boundary element method (BEM) and considering the sound absorption layer which is
covered on the backing of the sonar dome, the interior field in the dome which is excited by the incident plane wave has been
studied. This method is validated by comparing numerical results with that of classic elastic theory. Then the effect of parameters
of the sound absorption layer on interior sound field has been analyzed. The numerical calculation results show that uniformity
of interior sound pressure is improved when the backing is covered with a sound absorption layer. The thicker the layer is,
or the higher the loss factor of layer is, the more uniform the sound field is. 相似文献
942.
机载双站合成孔径雷达(BiSAR)对地面运动目标的检测与成像是雷达成像技术中一个重要研究内容.当地面目标运动时,目标回波信号方位向多普勒频率发生变化,带来图像位置偏移和散焦等问题.文中给出了跟随模式的BiSAR几何结构,在此基础上建立了地面成像区域目标的运动模型,进而研究了目标的不同运动分量对BiSAR成像的影响和BiSAR对动目标的检测和成像技术,并给出了计算机仿真结果. 相似文献
943.
944.
对一采用异型截面拱加固法加固的双曲拱桥进行有限元分析和试验研究,从理论上验证该加固方法的有效性和合理性.在总结已有研究成果的基础上,利用ANSYS分析软件中实体单位对加固后的双曲拱桥进行有限元模拟,假设新老混凝土结合面不产生滑移,且能够共同参与受力.通过计算结果与试验测量值进行对比,证明ANSYS软件中实体单元分析加固后双曲拱桥的可行性. 相似文献
945.
随着我国采用掘进隧道的方法开发地下空间的技术已经建立并不断完善,在保障和项目施工过程中的进度、安全等管理过程中,由于掘进隧道的建设规模越来越大,对于进度和质量要求也越来越高,所以拥有一款能够将管理规范化的盾构协同保障系统成为当前盾构企业的当务之急。上海盾构协同保障系统通过对盾构及相关业务管理的业务过程模型研究,建立协同保障系统的全局数据模型。进而实现整个系统。论文从盾构协同保障管理出发,结合当前国内外的先进管理模式,分析、设计和实现了上海盾构协同保障系统。 相似文献
946.
Fen-Ling Fan Yu-Liang Zou Ai-Qun Ma Hong-Yan Tian Jun-Bo Zhang Xian-Cang Ma Ya-Min Liu Zhi Hu Hong-Mei Wan Yu-Shun Zhang 《西安交通大学学报(英文版)》2010,22(3):192-197
Objective To investigate the change of plasma ghrelin level and explore the related factors of ghrelin alteration in elderly hypertensive patients with psychological distress. Methods A total of 300 elders, who were screened with Hamilton Anxiety Scale (HAMA), Hamilton Rating Scale for Depression (HAMD), and the Symptom Checklist-90 (SCL-90) for psychological stress and somato-psychological manifestations respectively, were divided into hypertension group (n=148) and non-hypertension group (n=152). Their blood samples were collected to measure the plasma level of ghrelin and total cortisol on the same day. Results The incidences of anxiety and depression were 27.7% and 11.7%, respectively, in all the enrolled elders. However, the rates of psychological distress, particularly anxiety, were significantly higher in the hypertensive elders than in the non-hypertensive ones (43.2% vs. 12.5%). Anxiety was positively related to the cortisol level but negatively related to the plasma ghrelin level, and the latter two were negatively correlated with each other. Conclusion Chronic increase of plasma cortisol induced by long-term anxiety can lead to the reduction of ghrelin level, which then adversely affects blood pressure in elders with psychological distress. Therefore, ghrelin might be a selective antihypertensive medicine for hypertensive elders with anxiety. 相似文献
947.
Rong-Guo Fu Li Wang Jian-Ping Zhou Feng Ma Xiao-Dan Liu Heng Ge Jun Zhang 《西安交通大学学报(英文版)》2010,22(3):203-207
Objective To investigate the effect of Levocarnitine on lipid metabolism and nutritional status of maintenance hemodialysis (MHD) patients and possible mechanism. Methods A total of 40 MHD patients [mean age (53.5±7.1) years] who underwent normal hemodialysis more than 6 months were randomly classified into two groups, Levocarnitine supplemented group (LS-G) (n=20; Levocarnitine supplementation after each normal hemodialysis session, at a dose of 1.0 g/day by intravenous administration) and control group (C-G) (n=20; normal hemodialysis). Before treatment, one month and three months after treatment we respectively measured or observed the following items, the tolerance to hemodialysis, carnitine level in plasma, C-reactive protein, IL-6, TNF-α, percentage of neutrophil, and some relevant nutritional parameters, such as lipid profile, transferrin, total protein, albumin and prealbumin levels. Comparative analysis was conducted between the two groups. Results In LS-G three months after treatment, the levels of carnitine, hemoglobin, and prealbumin in plasma were significantly increased (P<0.05), but C-reactive protein, neutrophil percentage, low-density lipoprotein and triglyceride were significantly decreased (P<0.05) in contrast to those in C-G and before treatment. Transferrin, total protein, and albumin were elevated in LS-G, with no statistical significance. Conclusion There was a significant improvement of lipid metabolism and nutritional status for the long-term maintenance hemodialysis patients with Levocarnitine supplementation. And this improvement is related to the decrease of inflammatory factors. 相似文献
948.
Yu-Liang Zou Jun Feng Wen-Li Gou Mei-Li Pei Fen-Ling Fan Zhong-Ming Zhang 《西安交通大学学报(英文版)》2010,22(4):260-264
Objective To study the inhibitory action of docetaxel (DOC) on the proliferation of HeLa and SiHa cells. Methods Cell morphological changes were observed with inverted phase contrast microscope. MTT was adopted to test and calculate the cell inhibition ratio. Flow cytometry was used to detect cell cycle. Results DOC had an obvious concentration-dependent inhibitory effect on the proliferation of both HeLa and SiHa cells. The inhibition ratio of DOC on SiHa was significantly higher than that on HeLa (P<0.05). DOC blocked HeLa at G2/M phase. Under the effect of DOC, the cell cycle of SiHa was not changed much. Conclusion DOC has an obvious inhibitory action on both HeLa and SiHa cells, which shows a promising prospect of DOC in clinical treatment of cervical cancer. 相似文献
949.
AC-13沥青混合料疲劳能耗模型分析 总被引:1,自引:0,他引:1
针对AC-13沥青混合料进行了不同试验条件下的疲劳试验;分析了每次加载下的耗散能与荷载作用次数之间的关系;利用数理统计的方法研究了试验条件对总累积耗散能与疲劳寿命的影响。结果表明:总累积耗散能与疲劳寿命之间的关系与荷载作用模式有关,与试验温度及加载频率无关。 相似文献
950.