基于UIO的摆式列车倾摆控制系统执行机构的故障检测

提出了一种利用未知输入观测吕（ＵＩＯ）对摆式列车倾摆控制系统执行机构进行故障检测的方法。该方法是干扰解耦原理的一个应用,通过一个全阶未知输入观测器使残差对未知输入不敏感,而对故障敏感,通过一个简单阈值逻辑来检测故障,通过计算机仿真证明了该方法的有效性。     

中国城市道路交通实时自适应控制与管理系统研究

针对中国城市道路交通的特点往交通控制系统的问题和未来发展的需要,提出了适用于中国城市的实时自适应控制与管理系统。     

Situation and prospects of shipboard integrated power system reconfiguration technology北大核心CSCD

当前,船舶综合电力系统(IPS)正朝着复杂化、模块化、自动化方向发展,研究快速、稳定、能够应对各种突发状况的船舶综合电力系统重构技术对保障船舶安全和可靠航行具有重要意义。首先,综述当前国内外在船舶综合电力系统重构技术方面的研究进展,讨论集中式重构和分布式重构的特点,并对数学优化算法、启发式算法、人工智能算法等进行归纳总结;然后,分析面对多重并发故障时重构技术所面临的困难与挑战,提出需重点关注混杂系统建模和分层分布式重构框架的建立;最后,从重构模型建立、算法优化、分布式架构等方面对未来船舶综合电力系统重构的发展提出设想和建议。     

走滑断层错动量大小对铁路隧道结构安全性影响的数值分析北大核心CSCD

走滑断层错动容易使穿越活动断裂带的隧道结构遭受严重的破坏。以某铁路隧道穿越某断裂带为工程背景,采用有限差分数值模拟手段,通过分析不同走滑断层错动量下隧道结构的位移、应力和应变,对隧道结构的安全性进行评判。研究表明:走滑断层错动时,除纵向位移外,随着错动量的增加,隧道结构位移越大,且走滑断层错动对在断层区和上盘区域的隧道结构影响最大;在走滑断层错动量>0.6 m后,隧道结构应力受错动量的影响较小,且隧道结构开始破坏,随着错动量增加,破坏范围增大。     

中国城市网约车服务对公交使用量的影响

城市网约车服务的蓬勃发展对包括公共交通在内的传统出行方式将产生影响.本文针对公交使用量的影响问题，运用109个城市数据做实证分析，并从网约车进入时长和城市类别做异质性检验.研究结果表明：网约车服务进入城市对城市公交使用量有明显的负向影响，且负向影响在超大型城市中更为严重；随着时间推移，网约车服务对公交使用量的负向影响呈现先增强后减弱的规律.研究结论揭示了中国城市网约车对公交的影响规律，对交通管理者制定相关政策具有参考意义.     

Ship resistance in random ice field of small ice floes made of the substitute material北大核心CSCD

［Objectives］This study focuses on the feasibility of a ship resistance model test in an ice field of small ice floes made of substitute material in order to reveal the resistance components and thereby provide technical support for the design of ice-going ships. ［Methods ］ Ship resistance test in ice floes made of polypropylene (PP) instead of natural refrigerated ice is conducted. By adjusting the sizes, shapes, numbers of ice floes, the random ice field with a given concentration is generated. The geometric phase transition theory predicts that there exists a critical concentration which divides the random ice field into discrete phase (concentration is less than critical value) and connected phase (concentration is greater than critical value). ［Results］The main components of ice resistance in the discrete phase are open water resistance and ship-ice collision resistance, while ice resistance in the connected phase includes ice friction resistance, open water friction resistance and collision resistance. If the fractal dimension of the random ice field is used to redefine the ice resistance coefficient, it is nearly constant in the trial range (speed 0.3–0.9 m/s) when the concentration is smaller than the critical value. When the concentration is greater than the critical value, the ice friction resistance is inversely proportional to speed. ［Conclusions］Polypropylene can replace frozen ice in the prediction of ice resistance. The pure ice resistance of an ice field is divided into two components: ice resistance arising from collision and ice friction resistance arising from accumulation. © 2022 Journal of Clinical Hepatology. All rights reserved.     

汽车轮胎滚动阻力试验机测试方法分析

为了对汽车轮胎滚动阻力测试方案的可行性进行预先评估,基于检测设备的结构模型,提出了一种运用位移量对轮胎滚动阻力进行仿真分析的新方法。在简述滚动阻力有限元测试模型构建过程的基础上,通过改变轮胎的外部使用参数,分析传感器板在不同工况下位移场的分布情况,制定了设备的测试方案。以传感器的安装位置作为目标检测点,建立轮胎滚动阻力位移场与控制参数之间的关系曲线。最后将采集的数据经过平均滤波处理,与实验室的实测数据进行了趋势性对比。结果表明：采用该测试方法,轮胎滚动阻力随着轮胎负载和速度的增加而增大,随着气压的变大而减小;仿真结果和试验数据在相同工况下的变化趋势基本一致;该测试方法合理、可行。     

路基和基层加固注浆材料的研究和应用

选用快硬硫铝酸盐水泥作为注浆材料基体,开展了缓凝剂品种、掺量和矿物外加剂掺量对注浆材料性能影响的研究,确定了路基加固用注浆材料和基层加固用注浆材料的最优配比：缓凝剂宜选用NMS,掺量为2‰;路基加固用注浆材料中1号矿物外加剂掺量为5％;基层加固用注浆材料中1号矿物外加剂掺量为20％。所制备的路基加同用和基层加固用注浆材料能较好地解决传统注浆材料凝结时间不易控制、强度稳定性差等问题,且实际工程应用效果良好。     

Shifting control of an automated mechanical transmission without using the clutch

The automated mechanical transmission (AMT) is gaining popularity in the automotive industry, due to its combination of the advantages of mechanical transmissions (MT) and automatic transmissions (AT) in terms of fuel consumption, low cost, improved driving comfort and shifting quality. However, the inherent structural characteristics of the AMT lead to disadvantages, including excessive wear of the clutch plates and jerk and traction interruption during the shift process, that severely affect its popularity in the automatic transmission industry. The emerging technology of shifting control without the use of the clutch is a promising way to improve the shifting transients of AMTs. This paper proposes a control algorithm that combines speed and torque control of the AMT vehicle powertrain to achieve shifting control without using the clutch. The key technologies of accurate engine torque and speed control and rapid position control of the shift actuators are described in detail. To realize accurate engine speed control, a combined control algorithm based on feed-forward, bang-bang and PID control is adopted. Additionally, an optimized closed-loop position control algorithm based on LQR is proposed for the shift actuators. The coordinated control algorithm based on engine and shift actuator control is described in detail and validated on a test vehicle equipped with an AMT. The results show that the coordinated control algorithm can achieve shifting control without the use of the clutch to improve driving comfort significantly, reduce shift transients and extend the service life of the clutch.     

Influence of the accelerating operation mechanism on the combustion noise in DI-diesel engines

This paper focuses on the mechanisms of combustion noise during the accelerating operation of multi-cylinder diesel engines using testing technology for the transient conditions of IC engines. Based on impact factors, such as the gas dynamic load and cylinder pressure oscillations, tests and analysis of the combustion noise during transient and steady-state conditions for different loads are made on four-cylinder naturally aspirated engines, turbocharged engines, EGR-introduced engines, and high pressure common rail engines. The laws of combustion noise difference for the same engine speed and load are researched during transient and steady-state conditions. It is found that during transient conditions, the maximum pressure rise rate and the high frequency oscillation amplitude of the cylinder pressure are all higher than those observed during steadystate conditions for the same engine speed and load. With their joint action, the combustion noise during transient conditions is greater than that during steady-state conditions. Turbocharging is useful in reducing the combustion noise during transient conditions. Turbocharging has a better effect on the control over the combustion noise during transient conditions with a constant engine speed and an increasing torque than in conditions with a constant torque and an increasing engine speed. One of the main reasons for different control effects on the combustion noise is that turbocharging causes different wall temperatures inside combustion chambers. The introduction of the appropriate EGR is helpful in the reduction of the combustion noise during transient conditions. The key to the control of combustion noise with EGR during transient conditions is whether a real-time adjustment to the EGR rate can be made to achieve the optimization of the EGR rates for different transient conditions. By means of analyzing the differences in the combustion noise between the transient and steady-state conditions for different pilot injection controls, we obtain a strategy for controlling the combustion noise during transient conditions with a pilot injection. Compared with the steady-state conditions, a larger pilot injection quantity and a longer interval between the main injection and pilot injection should be selected for transient conditions, and this is verified through tests.