浅谈PCMW工法在基坑支护工程中的施工工艺及质量控制

PCMW工法作为支护的新技术、新工艺,因其施工速度快、效果好以及止水质量容易保证等优点,已经开始广泛应用在难度较大、施工要求高的基坑支护工程中。结合具体工程实例,介绍了PCMW工法施工工艺以及质量控制方法。     

T型梁桥新增体外预应力施工控制

根据T形梁桥新增体外预应力工程施工特点,阐述了体外预应力施工过程中的施工平台设计、施工组织管理、施工工艺和主要质量控制点等内容,并针对工程中容易出现的问题,制定了相应的技术措施.     

对开路面弯道制动ABS控制策略研究

在对开路面弯道制动工况下分析了轮胎受力情况,提出一种基于转角预测前馈、路径偏移量反馈的车辆最佳滑移率动态调节方法,在SIMPACK中建立汽车多体模型,在MATLAB/Simulink中搭建控制系统,并进行了虚拟在环试验。试验结果显示,与传统ABS相比,所提出的控制方法可以显著改善车辆的侧偏位移、横摆角速度以及制动时方向的稳定性,保证了制动效能,使车辆侧向稳定性得到显著提高。     

双套拱塔斜拉桥索力张拉优化及控制

为研究双套拱塔斜拉桥施工控制技术,尤其是塔间索及斜拉索的张拉方案合理性及张拉控制方法,以小凌河大桥为背景,采用MIDAS Civil有限元软件建立该桥空间计算模型,进行施工过程的模拟计算,根据计算结果对拉索安装和张拉方案进行了优化。优化后,赋予塔间索初张拉无应力长度,二次调索时调整到成桥状态的无应力长度;斜拉索自内而外安装并张拉,索力小于250kN的斜拉索,调整其初张拉无应力长度使索力满足测量要求,其他斜拉索直接张拉到设计的无应力长度。监控结果表明,采用优化后的索力张拉方法对该类桥梁进行施工控制,整个施工过程中结构安全、受力明确,得到的成桥索力误差小。     

Technical Note: Force Control in Electrohydraulic Active Suspensions Revisited

The inner loop control for the actuator force can be quite simply compensated by means of a correction term to the desired force signal at the input. The correction requires only a measurement of the actuator piston velocity and is employed to cancel the loop disturbance caused by the oil flow to the actuator. Although an additional time constant is introduced by the integration in the inner loop force control, the overall performance is nevertheless quite close to that of an ideal optimal system.     

Development of advanced driver assistance systems with vehicle hardware-in-the-loop simulations

This paper presents a new method for the design and validation of advanced driver assistance systems (ADASs). With vehicle hardware-in-the-loop (VEHIL) simulations, the development process, and more specifically the validation phase, of intelligent vehicles is carried out safer, cheaper, and is more manageable. In the VEHIL laboratory, a full-scale ADAS-equipped vehicle is set up in a hardware-in-the-loop simulation environment, where a chassis dynamometer is used to emulate the road interaction and robot vehicles to represent other traffic. In this controlled environment, the performance and dependability of an ADAS is tested to great accuracy and reliability. The working principle and the added value of VEHIL are demonstrated with test results of an adaptive cruise control and a forward collision warning system. On the basis of the ‘V’ diagram, the position of VEHIL in the development process of ADASs is illustrated.     

A fundamental investigation of tilt control systems for narrow commuter vehicles

One way of addressing traffic congestion is by efficiently utilizing the existing highway infrastructure. Narrow tilting vehicles that need a reduced width lane can be part of the solution if they can be designed to be safe, stable, and easy to operate. In this paper, a control system that stabilizes the tilt mode of such a vehicle without affecting the handling of the vehicle is proposed. This control system is a combination of two different types of control schemes known as steering tilt control (STC) and direct tilt control (DTC) systems. First, different existing variations of both STC and DTC systems are considered and their shortcomings analysed. Modified control schemes are then suggested to overcome the deficiencies. Then a new method of integrating these two control schemes that guarantees smooth switchover between the controllers as a function of vehicle velocity is proposed. The performance of the proposed STC, DTC, and integrated systems is evaluated by carrying out simulations for different operating conditions and some experimental work. The design of a second-generation narrow tilting vehicle on which the developed control system has been implemented is presented.     

Vibration control in train–bridge–track systems

To study the problems associated with vibration control of train–bridge–track systems a mathematical model with the capability of representing supplementary vibrational control devices is proposed. The train system is assumed as rigid bodies supported on double-deck suspension mechanism with semi-active features. The bridge system is modeled using the modal approach. Vibration control for bridge responses is provided by tuned mass dampers. A non-classical incremental Eigen analysis is proposed to trace the system characteristics across the time. In an example, the capability of the proposed model in investigating the vibration control prospects of a bridge–train system is shown. The results indicate the effectiveness of active suspension mechanism in reducing train's body movements, particularly the pitching angle and the vertical accelerations. Accordingly, the results also verify the potential of TMD devices in reducing the bridge responses at resonance motions.     

Human driving data-based design of a vehicle adaptive cruise control algorithm

This paper presents a vehicle adaptive cruise control algorithm design with human factors considerations. Adaptive cruise control (ACC) systems should be acceptable to drivers. In order to be acceptable to drivers, the ACC systems need to be designed based on the analysis of human driver driving behaviour. Manual driving characteristics are investigated using real-world driving test data. The goal of the control algorithm is to achieve naturalistic behaviour of the controlled vehicle that would feel natural to the human driver in normal driving situations and to achieve safe vehicle behaviour in severe braking situations in which large decelerations are necessary. A non-dimensional warning index and inverse time-to-collision are used to evaluate driving situations. A confusion matrix method based on natural driving data sets was used to tune control parameters in the proposed ACC system. Using a simulation and a validated vehicle simulator, vehicle following characteristics of the controlled vehicle are compared with real-world manual driving radar sensor data. It is shown that the proposed control strategy can provide with natural following performance similar to human manual driving in both high speed driving and low speed stop-and-go situations and can prevent the vehicle-to-vehicle distance from dropping to an unsafe level in a variety of driving conditions.     

Lateral dynamics emulation via a four-wheel steering vehicle

In this paper, we examine the lateral dynamics emulation capabilities of an automotive vehicle equipped with four-wheel steering. We first demonstrate that the lateral dynamics of a wide range of vehicles can be emulated, either with little or with no modification on the test vehicle. Then we discuss a sliding mode controller for active front and rear wheel steering, in order to track some given yaw rate and side-slip angle. Analytically, it is shown that the proposed controller is robust to plant parameter variations by±10%, and is invariant to unmeasurable wind disturbance. The performance of the sliding mode controller is evaluated via computer simulations to verify its robustness to vehicle parameter variations and delay in the loop, and its insensitivity to wind disturbance. Finally, the emulation of a bus, a van, and two commercially available passenger vehicles is demonstrated in an advanced nonlinear simulator.