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Changes in the expression of platelet-derived growth factor in astrocytes in diabetic rats with spinal cord injury

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Chinese Medical Journal 2010年第12期123卷 1577-1581页

作者： WU Qiong-hua CHEN Wei-shan CHEN Qi-xin WANG jian-hong ZHANG Xiao-ming Department of Orthopedics Second Affiliated Hospital ZhejiangUniversity School of Medicine Hangzhou Zhejiang 310009China Department of Anatomy and Cell Biology Zhejiang UniversitySchool of Medicine Hangzhou Zhejiang 310058 China

Background Prospective mortality studies in the United States revealed that the mortality was elevated in diabetics compared to normal individuals following chronic spinal cord injury （SCI）. Our study was conducted to investigate the levels of platelet-derived growth factor （PDGF） of astrocytes in SCI in streptozotocin （STZ）-induced diabetic rats. Methods Thirty male Sprague-Dawley （SD） rats were randomly divided into 3 groups： SCI group, diabetic SCI group, and sham operation control group. We employed STZ-induced diabetic SD rats and a weight-drop contusion SCI model. The rats were sacrificed on day 7 after the induction of SCI. Immunohistochemistry and Western blotting analysis were used to detect the PDGF expression level. Basso, Beattie and Bresnahan locomotor rating scale （BBB） was also used to evaluate the neurological recovery level of the rats. Results PDGF positive astrocyte numbers were significantly higher and PDGF staining was more intensive in astrocytes in the SCI group than in the diabetic SCI group （P〈0.05）. The diabetic SCI group showed a slower recovery of motor function with a lower BBB score 7 days after acute spinal injury. Conclusions PDGF is an important factor for the recovery of neurological function after acute spinal injury and hyperglycemia in diabetic rats could depress the expression of PDGF in injured spinal cord. This may help to explain the slower recovery and higher mortality in diabetics after SCI.

关键词： platelet-derived growth factor spinal cord injury diabetes mellitus rat

抗差估计及Allan方差在车载组合导航系统中的应用研究

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兵工学报 2013年第7期34卷 889-895页

作者：吴有龙王晓鸣曹鹏南京理工大学机械工程学院江苏南京210094

针对组合导航系统中全球定位系统(GPS)信号易丢失和干扰、惯性导航系统(INS)无法长时间单独工作的问题,通过采用带故障检测和隔离的导航算法解决GPS数据异常的问题,有效提高系统的可靠性;同时当GPS卫星信号短时间丢失时,利用Allan方差... 详细信息

针对组合导航系统中全球定位系统(GPS)信号易丢失和干扰、惯性导航系统(INS)无法长时间单独工作的问题,通过采用带故障检测和隔离的导航算法解决GPS数据异常的问题,有效提高系统的可靠性;同时当GPS卫星信号短时间丢失时,利用Allan方差分析方法确定惯性传感器误差并进行补偿,使纯INS能够在一定精度内独立工作相对长的一段时间。车载试验结果表明:该方法能够保证组合导航系统的可靠性,且在GPS信号短时间丢失情况下提高了纯惯导系统的导航性能。

关键词：兵器科学与技术组合导航故障检测故障隔离 Allan方差

New self-calibration schemes for accelerometers of platform

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New self-calibration schemes for accelerometers of platform

谐振式MEMS压力传感器的制作及圆片级真空封装

第26届中国控制与决策会议

作者： Li Chan cao Yuan Ding Zhi-jian Cai Hong College of Aerospace Science and Engineering National University of Defense Technology

To guarantee success of precision navigation, it is necessary to carry out in-field calibration for the accelerometers of platform inertial navigation system（INS） before a mission is launched. Traditional continuous self-calibration methods are not fit for accelerometers’ fast calibration because the platform misalignments have to be estimated precisely and the nonlinear coupling terms will affect accuracy. Focusing on this field, the present paper proposes new fast self-calibration methods for the accelerometers of platform INS. Continuous calibration schemes are designed and optimized by the genetic algorithm（GA） to improve the observability of parameters. Simulations are conducted to analyze the performance and the sensitivity of the proposed methods. It is proved that the proposed methods can estimate the accelerometer parameter more precisely and more practical to deal with urgent situations than traditional methods.

关键词： accelerometers self-calibration platform INS the genetic algorithm

来源： cnki会议评论

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光学精密工程 2014年第5期22卷 1235-1242页

作者：陈德勇曹明威王军波焦海龙张健中国科学院电子学研究所传感技术国家重点实验室北京100190

为了提高传感器的品质因数,有效保护谐振器,提出了一种基于绝缘体上硅(SOI)-玻璃阳极键合工艺的谐振式微电子机械系统(MEMS)压力传感器的制作及真空封装方法。该方法采用反应离子深刻蚀技术(DRIE),分别在SOI晶圆的低电阻率器件层和基底... 详细信息

为了提高传感器的品质因数,有效保护谐振器,提出了一种基于绝缘体上硅(SOI)-玻璃阳极键合工艺的谐振式微电子机械系统(MEMS)压力传感器的制作及真空封装方法。该方法采用反应离子深刻蚀技术(DRIE),分别在SOI晶圆的低电阻率器件层和基底层上制作H型谐振梁与压力敏感膜;然后,通过氢氟酸缓冲液腐蚀SOI晶圆的二氧化硅层释放可动结构。最后,利用精密机械加工技术在Pyrex玻璃圆片上制作空腔和电连接通孔,通过硅-玻璃阳极键合实现谐振梁的圆片级真空封装和电连接,成功地将谐振器封装在真空参考腔中。对传感器的性能测试表明:该真空封装方案简单有效,封装气密性良好;传感器在10kPa^110kPa的差分检测灵敏度约为10.66 Hz/hPa,线性相关系数为0.99999 542。

关键词：微电子机械系统谐振式压力传感器绝缘体上硅(SOI) 阳极键合真空封装

Atmospheric Sulfur Deposition for a Red Soil Broadleaf Forest in Southern China

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Pedosphere 2004年第3期14卷 323-330页

作者： XUCheng-Kai HUZheng-Yi CAIZu-Cong WANGTi-jian HEYuan-Qiu caoZhi-Hong StateKeyLaboratoryofSoilandSustainableAgriculture InstituteofSoilScienceChineseAcademyofSciencesNanjing210008（China） DepartmentofAtmosphericScience NanjingUniversityNanjing210093（China）

A two-year study in a typical red soil region of Southern China was conductedto determine 1) the dry deposition velocity (V_d) for SO_2 and particulate SO_4^(2-) above abroadleaf forest, and 2) atmospheric sulfur fluxes so as to estimate the contribution of variousfractions in the total. Using a resistance model based on continuous hourly meteorological data,atmospheric dry sulfur deposition in a forest was estimated according to V_d and concentrations ofboth atmospheric SO_2 and particulate SO_4^(2-). Meanwhile, wet S deposition was estimated based onrainfall and sulfate concentrations in the rainwater. Results showed that about 99% of the drysulfur deposition flux in the forest resulted from SO_2 dry deposition. In addition, the observeddry S deposition was greater in 2002 than in 2000 because of a higher average concentration of SO_2in 2002 than in 2000 and not because of the average dry deposition velocity which was lower for SO_2in 2002. Also, dry SO_2 deposition was the dominant fraction of deposited atmospheric sulfur inforests, contributing over 69% of the total annual sulfur deposition. Thus, dry SO_2 depositionshould be considered when estimating sulfur balance in forest ecological systems.

关键词： atmospheric sulfur deposition dry deposition velocity particulateSO_4^(2-) red soil, SO_2

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基于支持向量机的语义视频摘要

北京邮电大学学报 2006年第4期29卷 94-98页

作者：曹建荣蔡安妮北京邮电大学电信工程学院

针对如何在语义层次上形成视频摘要问题,提出了一种基于支持向量机的风光纪录片语义视频摘要算法.利用支持向量机对镜头关键帧进行语义分类,对每类镜头关键帧根据引入的镜头“重要性”函数提取构建视频摘要的帧.改变重要性函数阈值的大... 详细信息

针对如何在语义层次上形成视频摘要问题,提出了一种基于支持向量机的风光纪录片语义视频摘要算法.利用支持向量机对镜头关键帧进行语义分类,对每类镜头关键帧根据引入的镜头“重要性”函数提取构建视频摘要的帧.改变重要性函数阈值的大小,可以方便地得到不同粒度的视频摘要.实验结果表明,该算法形成的视频摘要较好地表达了视频的内容.

关键词：支持向量机语义视频摘要

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微聚焦菲涅尔波带板聚焦特性研究

物理学报 2008年第5期57卷 3044-3047页

作者：董建军曹磊峰陈铭谢常青杜华冰中国工程物理研究院激光聚变研究中心绵阳621900 中国科学院微电子研究所北京100029

通过激光轰击Ti平面靶,用微聚焦菲涅尔波带板做成像器,测到了在放大倍数为6.6倍时X射线焦斑图像.利用Fresnel-Kirchhoff衍射积分公式数值模拟了微聚焦菲涅尔波带板的点扩展函数,模拟结果表明该微聚焦菲涅尔波带板在两倍焦距处强聚焦.改... 详细信息

通过激光轰击Ti平面靶,用微聚焦菲涅尔波带板做成像器,测到了在放大倍数为6.6倍时X射线焦斑图像.利用Fresnel-Kirchhoff衍射积分公式数值模拟了微聚焦菲涅尔波带板的点扩展函数,模拟结果表明该微聚焦菲涅尔波带板在两倍焦距处强聚焦.改变物距和像距但保持透镜的物像距公式,也可得到类似的结果.模拟和实验表明微聚焦波带板可以应用于X射线点对点成像,实现激光等离子体X射线高空间分辨成像.

关键词：菲涅尔波带板 Fresnel-Kirchhoff衍射数值模拟点扩展函数

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密度梯度薄板超高速撞击特性的实验研究

物理学报 2014年第2期63卷 206-215页

作者：侯明强龚自正徐坤博郑建东曹燕牛锦超中国空间技术研究院北京卫星环境工程研究所可靠性与环境工程技术重点实验室北京100094 中国空间技术研究院通信卫星事业部北京100094

以二级轻气炮作为加载手段,在撞击速度范围为4.0—7.0 km/s内获得了Ti6Al4V/Ly12 Al/聚酰胺纤维密度梯度薄板的穿孔特性、验证板损伤特性和弹道极限特性.与Ly12 Al薄板的相应实验结果的对比显示,在相同撞击速度下,该密度梯度薄板的穿孔... 详细信息

以二级轻气炮作为加载手段,在撞击速度范围为4.0—7.0 km/s内获得了Ti6Al4V/Ly12 Al/聚酰胺纤维密度梯度薄板的穿孔特性、验证板损伤特性和弹道极限特性.与Ly12 Al薄板的相应实验结果的对比显示,在相同撞击速度下,该密度梯度薄板的穿孔直径更大,且随撞击速度的增大而增加;其验证板上的撞击坑尺寸小,且随撞击速度的增大而减小;其弹道极限比Ly12 Al薄板的弹道极限高50%以上.分析认为,超高速撞击下Ti6Al4V/Ly12 Al/聚酰胺纤维密度梯度薄板中高阻抗的Ti6Al4V产生的峰值冲击压力比Ly12 Al薄板的峰值冲击压力高,这增强了对弹丸的破碎能力;而其中的聚酰胺纤维层延长了冲击波在薄板中的传播时间,增大了冲击波的耗散,使撞击过程中转化的不可逆功增多,从而消耗了弹丸更多的动能.使用这种密度梯度材料作为防护屏具有很好的抗撞击能力,在航天器空间碎片防护工程应用中具有很大的潜力.

关键词：超高速撞击密度梯度材料弹道极限空间碎片

Analysis of Accuracy of a High-speed Mobile Platform Control System

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厦门大学学报（自然科学版） 2002年第S1期41卷 38-39页

作者： RUAN jian, YUAN Ju-long, ZHANG Li-bin, JI Shi-ming, LI Sheng (College of Mechanical & Electrical Engineering, Zhejinag University of Technology, Hangzhou 310014, China)

The efficient manufacture technique involves a high-speed control of platform mobile system. A linear acutor is presented in this paper. The linear acutor is constructed as a linear stepper motor. However, to sustain both high accuracy and high speed for the position and speed control, A single-stack computer system is constructed and a special control algorithm is prescribed to controled the linear actuator continuously. In this paper, the nonlinear errors resulted from the magnetic saturation and the hysteresis is anaysis and discussed. In the view of electromagnetic propotional control, the actuator is a stage proportional magnet, because the driving current to the linear acuator changes for a number of cycles and a series of reset points will occur as the current undergoes cyclic changes. At each reset point the original starting characteristics of the system are re-established. A large number of reset points across the full stroke of the platform results in a significant reduction in the nonlinear behavior. The stage control is first discussed. Experiments carried out to obtain the characteristics of the mobile platform control system. It is demonstrated that with the introduction of stage control, nonlinearities, such as saturation and hysteresis, are greatly reduced, system stiffness is increased, and the positioning accuracy and resolution are improved. The effect of dither due to a "digital fragment" signal is also examined and found to be crucial in reducing the hysteresis and in improving the resolution accuracy.

关键词： high-speed control mobile platform nonlinearities