基于微观仿真的路段行程时间预测方法

实时路段行程时间预测是动态交通分配中路径选择的关键技术之一,采用微观交通仿真手段和指数平滑方法估计路段行程时间,在路段行程时间估计模型中考虑了交叉口排队延误、信号控制延误和交叉口内转向行程时间,提出了基于灰色等维新息GM(1,1)模型的路段行程时间预测方法,根据路段行程时间的历史数据和实时采集数据,滚动预测未来的路段行程时间,通过实例应用证明了模型有很好的预测精度.     

多跨系杆拱桥吊杆疲劳性能研究

以某三跨系杆拱桥为例,提出了一种拱桥吊杆的疲劳分析方法.对桥梁结构建立有限元模型求得各吊杆的索力影响线.依据交通量调查和交通量各参数的统计资料,将车辆概括为几种典型车型并计算其各参数的概率密度函数.基于蒙特卡罗方法模拟产生了通过桥梁的双向多车道车流作为疲劳荷载.针对典型吊杆的影响线加载模拟车流,得到杆件应力历程,用雨流法统计应力历程可以得到应力幅值谱.按照线性累积损伤理论和总交通量预测结果,计算得到各吊杆的在指定时间的累计损伤.     

城市区域交通信号智能控制及其微观仿真研究

城市交通的智能控制与管理是智能交通系统（ITS）的重要组成部分,也是当前研究的热点问题．针对交通问题复杂性、随机性和离散性的特点,采用自适应实数遗传算法对交叉路口信号灯进行优化,并以微观交通仿真系统代表真实交通系统来验证控制方案的优劣．开发了基于遗传优化的微观交通仿真系统,描述了该系统的子模型及实现方法;将该系统对一小型区域内信号灯的控制参数（周期,绿信比和相位差）进行同步优化,并通过微观交通仿真模型进行仿真实验;证实该方法能够在一定的范围内提高路网的通行能力,减少停车延误时间,从而缓解交通拥堵．     

铁路客运专线车站乘客集散微观仿真模型

为优化铁路客运专线车站的设计,研究了考虑不同发车频率的客流生成机制,应用标准的马尔可夫决策过程描述了乘客在车站内的集散过程,提出了基于逻辑网络和点阵的设备控制表示方法,建立了铁路客运专线车站乘客集散微观仿真模型.仿真发现:当行人移动空间在0.5 m2左右时,流量达到峰值,速度分布在20～80 m*min-1,并随密度增加呈指数递减趋势;在相同客流输入条件下,不同设施上的客流集散规律不同;通过对行人复杂行为的仿真,成功再现了客流集散中的自组织现象,有效避免了交通流基本图模拟现实交通中的不适应取值范围.结果表明模型具有较高的可靠性和实用性.     

白藜芦醇对急性胰腺炎治疗作用的研究现状与展望

关于急性胰腺炎(acute pancreatitis, AP)发病机制的研究,一直是国内外学者探讨的热点.对于AP发病的机制,目前主要有胰酶自身消化学说、微循环障碍学说、炎症因子与细胞介质学说、细胞内钙超载学说、肠道细菌易位与"二次打击"学说、氧化应激与NO作用学说等.白藜芦醇因具有抗炎、抗氧化、抑制血小板凝集、改善微循环等药理作用而受到临床工作者的广泛关注,是一种具有良好应用前景的天然药物.近年来,本课题就白藜芦醇对重症急性胰腺炎的治疗作用进行了大量深入的研究并做了系统的文献分析,认为白藜芦醇可以从多个环节发挥作用,从而起到缓解AP造成的胰腺损害及由此引发的多器官功能损伤.     

糖皮质激素预处理对兔心肌缺血再灌注损伤的保护作用

目的 探讨糖皮质激素对心肌缺血-再灌注损伤的保护作用.方法 将18只家兔应用冠状动脉左前降支结扎术造成心肌缺血模型,随机分成3组:心肌缺血再灌注损伤模型组(模型组)、糖皮质激素一次大剂量保护组(大剂量组)以及糖皮质激素多次小剂量保护组(小剂量组),每组6只.应用BL-420生物信号采集系统观察记录心电图ST段改变,分别在缺血前、缺血15 min以及再灌注30 min取血测定血浆丙二醛(MDA)浓度;缺血区心肌标本制作冰冻切片,行组织化学染色,观察缺血区琥珀酸脱氢酶活性变化.结果 糖皮质激素的大、小剂量保护组再灌注过程中ST段恢复的时间较短,快于模型组;大剂量组血清MDA水平低于小剂量组(P<0.05),且两组均低于模型组(P<0.01);大剂量组缺血心肌琥珀酸脱氢酶活性高于小剂量组,且两组均明显高于模型组.结论 糖皮质激素对心肌缺血-再灌注损伤可以起到有效的保护作用,一次大剂量的治疗保护效果要好于多次小剂量.     

Protective effect of glutamine pretreatment on ischemia-reperfusion injury of spinal cord in rabbits

Objective To investigate the effect of glutamine (Gln) on the content of reduced glutathione hormone (GSH) and aminoglutaminic acid (Glu) of spinal cord following ischemia-reperfusion injury. Methods Totally 40 healthy adult male rabbits were randomly divided into five groups: sham-operation group (S group), ischemia-reperfusion injury group (I/R group), low-dose glutamine group (L Gln group), median-dose glutamine group (M Gln group) and high-dose glutamine group (H Gln group). After glutamine preconditioning, the model of spinal cord ischemia-reporfasion injury was established according to Zivin's method. The general status of animals was observed and the changes of Jacobs scoring were recorded in each group. Malondialdehydes (MDA), GSH, Glu and superoxide dismutase (SOD) activity in lumbar spinal cord tissues were determined using chemical colorimetry. The neuron number and deviation rate in spinal cord anterior horn were observed histopathologically. Results There was no significant difference between L Gin group and I/R group in behavior scoring, SOD activity, content of MDA and Glu, neuron number and deviation rate of spinal cord (P>0.05); however, there was a significant difference in GSH content of spinal cord (P<0.05). M Gln group and I/R group differed significantly (P<0.05) in behavior scoring, SOD activity, content of MDA, Glu, GSH, neuron number and deviation rate of spinal cord. Between H Gln group and M Gln group, there was no significant difference in behavior scoring, content of MDA and Glu, SOD activity, neuron number and aberration rate in spinal cord (P>0.05), whereas there was a significant difference in SOD activity and Giu content (P<0.05). Conclusion Pretreatment with medium-dose glutamine has a protective effect on spinal cord ischemia-reporfasion injury in rabbits, which may be related to the maintenance of GSH content, increase of SOD activity and reduction of MDA.     

Effect of ulinastatin on hepatic ischemia-reperfusion injury in rats

Objective To investigate the effect of ulinastatin (UTI) on hepatic ischemia-reperfusion injury in rats. Methods Totally 24 adult Sprague-Dawley rats were randomly divided into 3 groups: sham-operated control group (SO group), ischemia-reperfusion group (I/R group) and ulinastatin group (UTI group). Liver in I/R group underwent 1 h of reperfasion after 30 min of ischemia. In UTI group, UTI (2×104 U/kg) was administered to rats 30 min before modeling. The levels of alanine aminotransferase, aspartate aminotransferase and tumor necrosis factor-alpha (TNF-α) in serum were measured and the levels of nitric oxide and malondialdehyde in liver were determined. The histological changes of liver were observed. Results The levels of alanine aminotransferase, aspartate aminotransferase and TNF-α in serum were significantly increased in I/R group compared with those in UTI group (P<0.05). The levels of nitric oxide and malondialdehyde in liver were significantly higher in I/R group than in UTI group (P<0.05).Histological examination of liver indicated that the damages were more severe in I/R group than in UTI group.Conclusion UTI has the ability to inhibit the production of TNF-α and oxyradical, and ameliorate microcirculatory dysfunction in rats with hepatic ischemia-reperfasion injury.     

综合识别指标在桥梁结构损伤识别中的应用

提出一种应用振动模态频率变化值和静力位移变化值之比而建立的综合识别指标对桥梁损伤进行分析与评定.试验结果表明,应用该方法能够对损伤的位置和程度进行准确的定位和评估.既安全又方便,可为现在的桥梁检测提供参考.     

负分层次三维纳米／微米氢氧化铝、氧化铝组装分化体系的建立及其微观机制研究

项目类型：面上项目 项目编号：50974026 项目摘要：本项目拟采用两条途径建立分层次三维纳米／微米氧化铝组装体系．在组装机制研究中重点研究铝源种类和表面活性剂类型对组装体系微观结构及性能的影响,探讨相关的组装机理,建立相应的组装模型．在分化机制研究中重点研究溶剂类型、改性剂种类及添加量等工艺参数对相结构演变以及微观形貌演变的影响,