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301.
302.
本文针对横向磁通永磁电机的功率因数,研究了最大转矩电流比控制方法,实现了横向磁通永磁电机最大转矩电流比控制仿真系统.仿真结果表明了该方法对提高横向磁通永磁电机动态性能和改善系统的功率因数的有效性. 相似文献
303.
中控交通综合管理信息系统以HIMS为依托,能完成对各种设备,交通事故统计等进行管理,生成对应的报表,系统基于.NET Framework环境,C#语言开发,采用分层架构设计,加入ASP.NET 2.0、Sql Server 2000、AJAX、NHibernate等技术,最终给用户提供简单易懂的管理界面,可以满足高速公路日常运营的无纸化办公管理. 相似文献
304.
基于动车组车体结构改进的低阶模态分析 总被引:1,自引:0,他引:1
车体前三阶模态特别是一阶垂向弯曲模态是车体设计中需要控制的一个重要参数.车体结构的改进设计,必然会使引起车体的振动模态数改变.因此分析出车体各大部件的结构变化对于车体低阶模态的影响因素及其规律,为车体创新性设计提供了一个可参考的设计原则. 相似文献
305.
To explore the significance of sacroiliac joint aerocele in the diagnosis of ankylosing spondylitis, the data of 196 patients
with ankylosing spondylitis (AS) were collected during December of 2008 to May of 2009. And 50 patients with osteoarthritis
(OA), 15 patients with sclerosing osteitis (SO) and 47 patients with sacroiliac joint tumors were investigated as the control
groups. The feature of sacroiliac joint aerocele in computed tomography (CT) images was observed carefully. In AS group there
were 130 patients (66.3%) diagnosed as AS according to CT results, and 32 of them (24.6%) were observed with aerocele within
sacroiliac joint cavity, majority of whom were earlier AS patients with slight bone destruction. Other 66 patients were diagnosed
as early AS according to magnetic resonance imaging (MRI) and ultrasonography. CT examination showed that the 66 patients
did not have apparent bone destruction, of whom, 26 (39.4%) patients had aerocele within sacroiliac joint cavity. Among the
control groups of 15 (15/50, 30.0%) patients with OA, 5 (5/15, 33.3%) patients with SO were observed sacroiliac joint aerocele.
The 47 patients with sacroiliac joint tumors were observed with bone or cartilage destruction, but without signs of sacroiliac
joint aerocele. The sacroiliac joint aerocele in CT images of AS patients usually appeared as spots, streaks, small or larger
round blocks, and it often happened in patients with earlier stage of diseases. Sacroiliac joint aerocele may be useful to
early diagnosis of AS. 相似文献
306.
To explore the possible mechanism of osteogenesis for deciduous teeth stem cells (DTSCs) in vivo/ vitro, stem cells from goat
deciduous teeth (SGDs) were firstly isolated, induced and transplanted into immunocompromised mice. The SGDs’s mineralization
pattern and osteogenesis were compared with bone marrow messenchymal stem cells (BMMSCs) from goats. SGDs have similar osteogenic
differentiation pattern in vitro and bone-like tissue formation mechanism in vivo to BMMSCs; moreover SGDs have stronger alkaline
phosphatase (ALP) gene expression and osteopontin (OPN) gene expression levels than BMMSCs; also SGDs can form more bone-like
tissues than BMMSCs when cell-scaffold compounds are transplanted into immunocompromised mice. This pre-clinical study in
a large-animal model confirms that DTSCs may be an appropriate source of stem cells in repairing bone defects with tissue
engineering. 相似文献
307.
Collaborative spectrum sensing is proposed to improve the detection performance in cognitive radio (CR) networks. However,
most of the current collaborative sensing schemes are vulnerable to the interference of the malicious secondary users (SUs).
In this paper we propose a reputation-based collaborative spectrum sensing scheme to improve the security of cooperative sensing
by mitigating the impacts of misbehaviors. The fusion center calculates the reputation rating of each SU according to their
history reports to weight their sensing results in the proposed scheme. We analyze and evaluate the performance of the proposed
scheme and its advantages over previous schemes in expansibility and integrity. Simulation results show that the proposed
scheme can minimize the harmful influence from malicious SUs. 相似文献
308.
结合嘉陵江草街航电枢纽模型试验,研究枢纽下游局部冲刷对河床变形带来的影响,初步分析了枢纽建成后下游河床冲淤变化机理,从而有利于预测枢纽建成后下游河床冲淤变形趋势. 相似文献
309.
研究了流-固耦合相互作用的声散射问题.基于DtN映射方法,将无界区域化为有界区域,证明了等价性;基于变分原理,证明了求解这类声散射问题的一种自然边界元与有限元耦合的求解方法,并证明了解的存在性和惟一性. 相似文献
310.