Simulation of mixed gas formation for a spray-wall complex guided LPG direct injection engine

To obtain an ultralean air-fuel ratio and to reduce engine-out NOX and HC emissions induced by the richer mixture near the spark plug, a spray and wall complex guided combustion system has been developed by utilizing the fuel characteristics of LPG. The new combustion system configuration is optimized by using a commercial CFD code, FIRE V2013, and the reliability of the system has been experimentally demonstrated by Plane Laser-Induced Fluorescence (PLIF). The mixture formation in the new combustion system under part load (2,000 rpm) is numerically simulated. With an injection timing of 40°CA BTDC, the LPG spray which is injected from two upper holes, reaches the ignition point, and the other part of the LPG spray which is injected from the bottom hole, is directed to the ignition point through the vertical vortices at the same time. At the ignition timing of about 20°CA BTDC, the two-part mixtures have been shown to form a stable and richer stratified mixture around the ignition point, and the maximum global air-fuel ratio reaches to 60: 1.     

A new model for temporal–spatial stochastic analysis of vehicle–track coupled systems

The vehicle–track coupled system has a random nature in the time–space domain. This paper proposes a computational model to analyse the temporal–spatial stochastic vibrations of vehicle–track systems, where the vehicle–track system is divided into a vehicle subsystem, track subsystem, and interfacial subsystem between the wheel and rail. In this model, the time-varying randomicity of dynamical parameters of the vehicle system, correlation, and randomness of the track structural parameters in the time–space joint dimensions, and randomness of the track random irregularities are considered. A probability dimension-reduction method was used to randomly combine different random variables. Furthermore, the probability density evolution method was applied to solve the delivery problem of probabilities between excitation inputs and response outputs. The temporal–spatial stochastic vibrations of the vehicle–track system with different coefficients of variation were studied, in which we assumed that the dynamic parameters obeyed the normal distribution, and the stochastic simulation method of the track random irregularities is probed into. The calculated results from this model are consistent with the actual measured results and physical conceptions. Thus, the temporal–spatial stochastic evolutionary mechanism can be explored, and the limits of dynamic indices can be formulated by using this developed model.     

布达佩斯城市交通发展战略与启示

分别从概况、战略目标、实施策略等3个方面对布达佩斯城市交通发展的总体战略及公共交通、道路网络、静态交通、步行及自行车交通、交通管理等发展战略进行了阐述。由此得出,居民出行线路上任何一种交通方式的低效都将破坏整个交通链的效率,只有整个交通链所有交通环节的和谐发展,才能够使公共交通在运输服务上较小汽车具有竞争力;只有综合利用公共交通与私人交通,才能使城市交通与土地利用相协调。最后,结合布达佩斯和国内实践经验,总结提出了一种包含人口、经济、地理、环境、技术、制度等要素的“六棱形”城市交通发展战略规划模型。     

Modeling research on manufacturing execution system based on large-scale system cybernetics

A cybernetics model of manufacturing execution system(MES CM) was proposed and studied from the viewpoint of cybernetics.Combining with the features of manufacturing system, the MES CM was modeled by"generalized modeling"method that is discussed in large-scale system theory.The mathematical model of MES CM was constructed by the generalized operator model, and the main characteristics of MES CM were analyzed.     

快速老化小鼠的学习记忆缺陷及其生化机制

目的用快速老化小鼠(SAMP8)模拟老年痴呆,观察其学习记忆能力,并探讨其学习记忆能力下降的可能机制。方法采用10月龄SAMP8,并用同龄抗快速老化小鼠(SAMR1)作为正常对照。用水迷路检测近记忆以及空间学习记忆能力。用生物化学方法检测大脑皮层线粒体膜电位和ATP酶活力,观察线粒体功能;检测皮层和海马胆碱乙酰基转移酶(ChAT)和乙酰胆碱酯酶(AChE)的活力,观察中枢胆碱能神经功能;检测血清超氧化物歧化酶(SOD)活力和丙二醛(MDA)含量,观察其全身性氧化应激状况。结果与SAMR1相比,SAMP8出现明显的衰老体征,其近记忆和空间学习记忆能力明显减弱,具有衰老和痴呆特征;皮层线粒体膜电位和ATP酶活力显著降低,海马ChAT活力显著下降,AChE活力显著升高,血清SOD活力稍有增高。结论SAMP8可以很好地模拟老年痴呆,其机制包括大脑皮层线粒体功能降低、海马胆碱能神经功能下降以及氧化应激等。     

新时期高职院校党建工作存在的问题及对策

文章通过分析目前高职院校党建工作存在的发展不平衡、学生党员入党前后的形象不和谐、学生党员整体作用不明显等问题,提出了深入基层宣传、抓好学生党员再教育、推进党员责任区工作、发挥教师党员教书育人作用以及加强流动党员管理等对策。     

现浇薄壁筒桩技术及其施工工艺

介绍现浇混凝土薄壁筒桩技术以及与其它形式桩基技术的比较.     

饲料加硼对摄入过量氟的实验大鼠骨损伤的预防作用

目的探讨饲料加硼对过量氟摄入的大鼠骨损伤的预防作用。方法24只4-5周龄Sprague-Dawley(SD)大鼠分为:对照组(喂饲基础饲料,饮蒸馏水)、过量氟组[喂饲基础饲料,饮含100mg/LF-(氟化钠221mg/L的蒸馏水)]、硼预防组(喂饲加硼饲料,饮含100mg/LF-的蒸馏水)。实验3月后测量大鼠血清氟、硼含量及血清碱性磷酸酶(alkaline phosphatase,AKP)活性、骨氟和骨总RNA含量、胫骨纵径横径和干重及骨密度(bone mineral density,BMD),并检测大鼠股骨生物力学特性。结果和对照组比较,过量氟组大鼠血清氟、骨氟含量和血清AKP活性显著增高;骨总RNA含量、全身骨骼平均BMD和胫骨BMD降低;胫骨纵径、横径和干重减小;股骨最大负荷减低,最大形变增加。相比过量氟组,硼预防组大鼠血清氟和骨氟含量及AKP活性明显下降;骨总RNA含量、全身骨骼平均BMD、腰椎和胫骨BMD显著增高;胫骨纵径、横径和干重,股骨最大负荷明显增加。3组大鼠血清硼含量无显著性差异。结论大鼠摄入过量氟可出现明显的骨损伤,饲料加硼对此有一定的预防作用。     

基于决策偏好的ETC系统评价指标体系及评价方法

为更好地反映不同决策者对电子收费系统（ETC）评价的偏好,从政府、运营者和付费者三个主要利益主体的角度对ETC系统的评价指标及评价方法进行了研究。根据评价指标体系筛选原则,确定了基于决策偏好的ETC系统评价指标体系;通过综合分析成本-效益法（CBA）和数据包络分析法（DEA）的各自特点,依据基于决策偏好所确定的评价指标,同时引入当前一些比较好的算法来优化CBA,DEA和AHP法,建立数学模型,从而确立了基于决策偏好的综合评价方法。该方法较为全面地对ETC系统社会经济影响进行评价,所建立的指标体系和方法能更直观、更可靠地反映出决策者的决策偏好。     

中国铁路提速后技术进步对产出贡献的测算

选取我国铁路提速后1997~2007年间的相关数据,采用基于科布——道格拉斯生产函数的Solow余值法,将有限分布滞后模型和半参数回归模型引入计算模型,对数据进行拟合,计算得到铁路提速后技术进步、固定资本投入以及人力资本投入对产出的贡献率,并根据计算结果提出促进我国高速铁路建设的相关对策建议.