The uplift capacity of single-plate helical pile in shallow dense sand including the influence of installation

The helical pile has been used to resist the tension for a long time. However, the prediction of the uplift capacity of helical piles including the influence of installation is still a challenge in design. Based on the change in stress according to Mohr-Coulomb failure criterion, a simple theoretical method has been developed, which can calculate the uplift capacity of shallow pre-embedded circular plate anchors and the uplift capacity of helical piles installed by torque and compression. In order to analyse the influence of installation process of a single-plate helical pile on its uplift capacity and verify the theoretical model, a series of model tests have been conducted in dense saturated sand. The single-plate helical piles with different out diameters of helixes have been installed with different installation speeds, and then, the single-plate helical piles have been moved up monotonically. The test results show that the installation speed and the size of the out diameter of the helix have significant influence on the uplift capacity of the helical piles, and the results of the theoretical method have a good fit with the test results. Using this simple theoretical method, the designer can easily predict the uplift capacities of helical piles, which includes the influence of installation.     

带有改编能力限制的编组计划优化模型及算法

本文用一个非线性０－１规模模型，来描述带有改编能力限制的技术直达列车编组计划问题。能力约束增加了该问题的计算难度。这是一个ＮＰＣ问题。因此，获得一个全局最优解是困难的。本文用模拟退火算法解该问题。该算法可以以很高的概率获得全局最优解。文末列出了两个数值例子，并分别同了考虑和不考虑改编能车约束两种情况下的计算结果。     

接地线对微机继电保护设备的抗扰度影响试验分析

为了提高电子设备电路系统工作的稳定性，同时泄放由静电感应在机箱上积累的电荷，避免电荷积累形成的高压导致设备内部放电而造成干扰，为设备和操作人员提供安全保障，接地是一项极其必要的措施。但在干扰情况下，接地线的接地效果及其对设备的影响到底怎样，还并未做过详细试验。针对与此，对微机继电保护设备采用不同接地线时所能承受的干扰电压进行试验，并总结分析，提出设计及工程人员实际工作中应注意的问题。     

盾构穿越始发段土体加固区时土体沉降扰动分析

在整个盾构的掘进施工过程中,其始发段施工是事故频发的危险区段。为此,以武汉市地铁江汉路到积玉桥越江段施工为背景,选用FLAC3D软件对盾构穿过始发段全过程的土体扰动规律进行分析。数值仿真分析结果表明:在始发阶段盾构经过土体加固区时,土体横断面沉降槽呈现正态分布规律;将土体加固后,加固区的地表沉降很小,表明加固区土体受到的盾构施工扰动效应较非加固区明显减小;盾构中部通过加固区和非加固区分界面时地表沉降增加速率最大,盾构机前部和尾部通过时地表沉降增加的速率较小;盾构掘进过程中非加固区土层的沉降槽均呈现正态分布,盾构掘进主要影响盾构开挖洞口横向两侧18~22 m范围内土体,以及纵向15~20 m范围内的土体。     

货物列车编组计划国内外研究综述

货物列车编组计划(TFP)在铁路运输组织工作中具有非常重要的作用,其编制是一项复杂的课题。目前,在编组计划编制理论和方法研究上取得了丰硕的成果。本文从研究对象、建模方法、求解算法分别介绍国内外TFP的研究现状;在此基础上,对比并评述国内外编组计划在编制流程、构成内容和建模方法3个方面的特点;最后探讨在优化方法和优化内容上进一步研究的思路。     

考虑横向漂移的船舶路径跟踪自抗扰控制

针对船舶运动系统中内部动态不确定和外部干扰等问题,进行了欠驱动船舶路径跟踪的自抗扰方法研究。利用Backstepping设计参考航向角,并通过线性扩张状态观测器对流干扰和横向运动引起的横向漂移进行估计。其次,根据自抗扰算法对航向进行控制,采用线性扩张状态观测器对外界干扰及内部不确定项进行估计。最后仿真结果表明,在风流干扰下所设计的控制器仍能使船准确地跟踪上参考路径,验证了所提控制方案的有效性。     

Vehicle platoon formation using interpolating control: A laboratory experimental analysis

This work addresses the formation phase of automatic platooning. The objective is to optimally control the throttle of vehicles, with a given arbitrary initial condition, such that desired ground speed and inter-vehicular spacings are reached. The steering of the vehicles is also controlled, because the vehicles should track a desired path while forming the platoon. In order to address the platoon formation problem, a cooperative strategy is formed by constructing a discrete state space model which represents the dynamics of a set of n vehicles. Once this model is set, a control method known as Interpolating Control, which aims at regulating to the origin an uncertain and/or time-varying linear discrete-time system with state and control constraints, is utilized. The performance of this control method is evaluated and compared with other approaches such as Model Predictive Control (MPC).Simulations are conducted which suggest that the Interpolating Control approach can be seen as an alternative to optimization-based control schemes such as Model Predictive Control, especially for problems for which finding the optimal solution requires calculations, where the Interpolating Control approach can provide a straightforward sub-optimal solution.In the experimental part of this work, the control algorithms for the platoon formation and path tracking problems are combined, and tested in a laboratory environment, using three mobile robots equipped with wireless routers. Validation of the proposed models and control algorithms is achieved by successful experiments.     

VVL耦合喷油策略对GDI汽油机混合气形成的影响

利用三维仿真软件Ansys Fluent建立了GDI汽油机的仿真计算模型,就变气门升程耦合不同喷油策略对缸内气流运动和混合气形成的影响进行了模拟计算。结果表明,与大气门升程工况相比,小气门升程工况的缸内湍流运动强度、燃油蒸发和湿壁情况以及点火时刻混合气质量都明显改善;在小气门升程工况,采用两段喷油会缩短油气混合时间,过度推迟二次喷油时刻会恶化混合气质量和燃油湿壁情况;在大气门升程工况,两段喷油会改善混合气均匀性,随着二次喷油时刻推迟,燃油蒸发量增加,湿壁情况加剧,混合气质量得到改善;小气门升程工况下采用二次喷油时刻为470°曲轴转角,前后两次喷油量比例为7∶3的两段喷油方案在燃油蒸发和湿壁以及点火时刻缸内混合气质量这几个方面的效果都很好,是最合理的方案。     

基于数据链的航母编队评估指标体系研究*

数据链是航母编队的中枢系统,对作战指控过程有重要作用,各作战单元与指控中心之间的情报传递与命令下达等信息均通过数据链进行传输,因此,对航母编队作战效能评估也应当建立在数据链性能指标上。论文以航母编队防空作战为例,分析了在防空作战过程中,数据链性能指标对指挥质量及效能指标的影响,建立了防空作战评估指标体系。     

初探高职工业设计专业《平面构成》课程教学改革与创新

文中介绍了平面构成的概念、目的,通过分析平面构成现存的问题及高职平面构成面临的新问题,探索高职工业设计专业《平面构成》课程教学改革与创新。