散癖平胃方对人胃癌细胞SGC-7901侵袭转移的影响

目的观察散癖平胃(SPPW)方对人胃癌细胞SGC-7901侵袭转移能力的影响。方法 SPPW方含药血清干预人胃癌细胞SGC-7901 48h后,应用黏附实验、侵袭实验及迁移实验,检测SPPW方对人胃癌细胞SGC-7901侵袭转移能力的影响。应用实时定量聚合酶链反应(real-time PCR)检测SPPW对与侵袭转移有关的MMP-2和MMP-9mRNA表达的影响。结果 SPPW方各组含药血清干预人胃癌细胞48h后,SGC-7901细胞黏附抑制率、侵袭抑制率及迁移抑制率均增加且呈剂量依赖关系,与阴性对照组比较有统计学差异(P<0.01或P<0.05)。SPPW方三个剂量组对MMP-2mRNA的表达无统计学差异,对MMP-9mRNA的表达具有统计学差异(P<0.01)。结论 SPPW方可抑制人胃癌细胞SGC-7901黏附、侵袭和迁移能力,其抑制有明显的剂量依赖性,其抑制的机制可能与下调MMP-9的表达有关。     

Formula One与Delphi的集成

阐述在Delphi中通过ODBC方式，Formula One与数据库联结的建立方法，结合例程讨论了数据文件的读写、数据交换、格式设置及报表处理技巧，为Delphi与第三方控件的集成提供一种思路．     

Magic Formula轮胎模型参数辨识的一种混合优化方法

Magic Formula(MF)轮胎模型能够准确描述轮胎的侧偏特性,广泛应用于车辆动力学的研究。由于MF轮胎模型参数多,且高度非线性,从大量的试验数据中准确辨识这些参数相当困难。提出一种基于遗传算法和数值优化算法的混合优化方法,采用由粗到精的辨识过程,先利用遗传算法得出近似最优解,再利用数值优化算法辨识出精确的参数。利用辨识出的参数计算轮胎的侧偏特性,计算结果与试验数据吻合良好,表明该方法是辨识MF轮胎模型参数的有效手段。     

关于细化铁路曲线上建筑限界加宽的建议

通过分析某中间站低站台与SS9G型机车脚蹬刮擦事故，指出铁路曲线上建筑限界垂向加高及降低的重要性。根据《铁路技术管理规程》和GB146．2—1983标准轨距铁路建筑限罗酚相关规定，建议加入铁路曲线建筑限界垂向加高及降低的规定和计算公式，细化曲线上建筑限界加宽办法。     

Optimal tyre usage for a Formula One car

Variations in track temperature, surface conditions and layout have led tyre manufacturers to produce a range of rubber compounds for race events. Each compound has unique friction and durability characteristics. Efficient tyre management over a full race distance is a crucial component of a competitive race strategy. A minimum lap time optimal control calculation and a thermodynamic tyre wear model are used to establish optimal tyre warming and tyre usage strategies. Lap time sensitivities demonstrate that relatively small changes in control strategy can lead to significant reductions in the associated wear metrics. The illustrated methodology shows how vehicle setup parameters can be optimised for minimum tyre usage.     

Effect of the front and rear weight distribution ratio of a Formula car during maximum-speed cornering on a circuit

Because Formula cars are lighter than ordinary cars, the optimal settings for this type of car are thought to be different from those of a ordinary car. The front and rear weight distribution ratio of a vehicle is an important parameter that exerts a significant influence on critical cornering. The tendency of a ordinary car to under-steer during critical cornering is determined by the front and rear weight distribution ratio of the vehicle. Specifically, when the front of an ordinary FR (front-engine, rear wheel drive) vehicle is slightly heavier than the rear, the car tends to understeer during critical cornering. However, the optimal weight distribution ratio for critical cornering is not obvious for a formula car because of its lightness. This observation was investigated using a driving course similar to a real driving course to perform a maximum speed cornering simulations. It was found that a front to rear weight distribution ratio of 40:60 resulted in the fastest lap time. This ratio also gave the best results in the maximum-speed driving experiment performed using a driving simulator. Moreover, the maximum lateral acceleration during turning, the driving force, and the load movement of the inside and outside wheels was calculated using experimental driving force data and the concept of a tire friction circle. As a result, driving mechanics have been determined for a vehicle having a front/rear weight distribution ratio of 40:60 while traveling at maximum speed.     

长呼线和马惠线夏季运行方式对比分析

长呼线和马惠线都是输送长庆油田原油的长输管道。马惠线采用裸管,夏季采用常温输送方式,而长呼线采用保温管道,夏季却采用加热输送方式。文中从所输油品物性,管道沿线地温、管线总传热系数、油品输送距离等方面对比分析长呼线和马惠线的差异,探讨限制长呼线夏季常温输送可行性的因素,提出了长呼线夏季运行方式的优化方案,建议长呼线夏季采用首站不加热、中间站加热的运行方式。     

电动方程式赛车悬架系统设计与仿真

依托电动方程式赛车比赛要求,选取适合电动方程式赛车的悬架类型,对悬架进行合理的设计,并进行车轮定位参数的设定和刚度计算等,然后使用CATIA软件对悬架重要零部件进行建模,导入ANSYS软件对悬架的重要部件进行受应力分析。分析结果表明,此悬架系统重要部件刚度强度符合要求,赛车安装后可以安全行驶。     

Flexural buckling of circular concrete-filled stainless steel tubular columns

Concrete-filled steel tubular (CFST) columns are currently used in offshore structures and oil and gas drilling platforms, from which the external steel tubes become at risk due to the aggressive ocean climate and/or sea water. Therefore, the CFST columns in corrosive environment lose their excellent mechanical performances and safety as the thicknesses of steel tubes decrease due to corrosion. This has recently led to the introduction of the concrete-filled stainless steel tubular (CFSST) columns, which benefit from the stainless steel as a superior metallic corrosion resistant material. Accordingly, CFSST short columns have recently attracted the scientific community. However, circular CFSST slender columns have received very little attention. Currently, this paper provides a nonlinear finite element (FE) inelastic analysis for the axially-loaded circular CFSST slender columns to substitute the lack in their behaviour; especially when the relative cheap lean duplex stainless steel material (EN 1.4162) is utilised. The FE models are firstly validated by using the available test results in literature. This validation stage is, then, followed by a parametric analysis to explore the fundamental behaviour of such columns considering the most important factors. The paper divides the slender columns into intermediate length and long columns based on the type of the overall buckling that takes place, and then the behavioural differences between both types are clearly addressed. The obtained FE axial strengths are additionally compared with those predicted by the European (EC4) and American (AISC) specifications. Based on these comparisons, a formula, based on Eurocode 4, is suggested for the routine compressive design practice of these columns, which is found to fit well with the axial strengths of current slender columns which utilise the lean duplex stainless steel material.     

绝缘缓冲橡胶垫板低温性能影响因素研究

高寒地区高速铁路扣件系统中的橡胶垫板性能受低温影响较大。通过不同配方和不同工艺的绝缘缓冲橡胶垫板的低温脆性试验研究了绝缘缓冲橡胶垫板低温性能的影响因素。研究结果表明:胶料中顺丁橡胶(BR)的含量越高,绝缘缓冲橡胶垫板的低温性能越好;增塑剂DOP,DOS和45#变压器油对绝缘缓冲橡胶垫板在-60℃的低温性能不利;选用不同生产厂家的炭黑对绝缘缓冲橡胶垫板低温性能的影响没有本质区别;低温慢速硫化工艺相对于高温快速硫化工艺更有利于绝缘缓冲橡胶垫板的低温性能。