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751.
利用沪宁高速公路扩建工程铣刨旧料为原材料,采用WLB10泡沫沥青发生装置,对沥青发泡的性能进行了研究,并探讨了泡沫沥青冷再生混合料配合比设计方法,通过对泡沫沥青再生混合料与热拌沥青混合料性能的比较,提出了泡沫沥青再生的使用范围。 相似文献
752.
753.
在《公路桥规》(JTJD62-2004)给出的钢筋混凝土构件纵向受拉钢筋最小配筋率的基础上,本文充分考虑到组合梁的横截面几何特性,用Mathematica4.0计算任意截面梁纵向受拉钢筋最小配筋率,并对其在旧桥改造中的应用特例进行分析,可供工程技术人员参考使用。 相似文献
754.
电动助力转向技术发展的新动向 总被引:2,自引:0,他引:2
1EPS概述按照转向动力源来分,目前汽车转向系统分为纯人力转向和动力辅助转向,后者又经历了机械机构助力转向、液压助力转向和电动助力转向3个阶段。目前,电动助力转向(ElectricalPower Steering,EPS)已部分取代液压动力转向(Hydrau licPowerSteering,HPS),正成为世界汽车技术发展的热点。EPS是一种直接依靠电力提供辅助扭矩的动力转向系统,它用电动机提供助力,助力大小由电控单元(ECU)控制,系统主要由扭矩传感器、转角传感器、车速传感器(可与其他系统共用)、电动机、减速机构和电子控制单元等组成,其基本工作原理是:装在转向器上… 相似文献
755.
756.
Detection of weak underwater signals is an area of general interest in marine engineering. A weak signal detection scheme
was developed; it combined nonlinear dynamical reconstruction techniques, radial basis function (RBF) neural networks and
an extended Kalman filter (EKF). In this method chaos theory was used to model background noise. Noise was predicted by phase
space reconstruction techniques and RBF neural networks in a synergistic manner. In the absence of a signal, prediction error
stayed low and became relatively large when the input contained a signal. EKF was used to improve the convergence rate of
the RBF neural network. Application of the scheme to different experimental data sets showed that the algorithm can detect
signals hidden in strong noise even when the signal-to-noise ratio (SNR) is less than −40d B. 相似文献
757.
It can be beneficial to reduce vibrations in shipboard piping, so the authors designed a new kind of piping damper with a
plunger-type accumulator. Special requirements for the piping damper included low impact displacement, low speed, as well
as an appropriate locking speed. Inside the damper, a plunger-type accumulator was installed and on the outside of the piston
rod, a tube with exposed corrugations was added. Between the piston and the cylinder, a clearance seal was added. Using mathematical
modeling, the effects of the dynamic performance of the damper’s impact displacement on vibrations were observed. Changes
to the clearance between the piston and the cylinder, the stiffness of the spring in the accumulator, the throttle valve size,
and locking speed resistance of the damper were respectively simulated and studied. Based on the results of the simulation,
dampers with optimal parameters were developed and tested with different accumulator spring stiffnesses and different throttles.
The simulation and experimental results showed that parameters such as seal clearance between piston and cylinder, accumulator
spring stiffness and throttle parameters have significant effects on the damper’s impact displacement, low speed resistance
and locking speed. 相似文献
758.
水下潜器改进S面控制及控制系统仿真(英文) 总被引:1,自引:0,他引:1
S surface controllers have been proven to provide effective motion control for an autonomous underwater vehicle (AUV). However,
it is difficult to adjust their control parameters manually. Choosing the optimum parameters for the controller of a particular
AUV is a significant challenge. To automate the process, a modified particle swarm optimization (MPSO) algorithm was proposed.
It was based on immune theory, and used a nonlinear regression strategy for inertia weight to optimize AUV control parameters.
A semi-physical simulation system for the AUV was developed as a platform to verify the proposed control method, and its structure
was considered. The simulation results indicated that the semi-physical simulation platform was helpful, the optimization
algorithm has good local and global searching abilities, and the method can be reliably used for an AUV. 相似文献
759.
边界任意弹性约束薄板的横向振动(英文) 总被引:1,自引:0,他引:1
This paper presents an analytical study on the influence of edge restraining stiffness on the transverse vibrations of rectangular
plate structure. An improved Fourier series method was employed to analyze the transverse vibration of plate structure with
general elastically restrained boundary conditions. A linear combination of a double Fourier series and eight auxiliary terms
was sought as the admissible function of the flexural displacement of the plate, each term being a combination of a polynomial
function and a single cosine series expansion. The auxiliary terms were introduced to ensure and improve the smoothness of
the original displacement function and its derivatives at the boundaries. Several numerical examples were given to demonstrate
the validity and accuracy of the current solution. The influences of translational and rotational stiffness on the natural
frequencies and mode shapes of plate were analyzed by numerical results. The results show that the translational stiffness
has bigger influence on the natural frequencies than the rotational stiffness. It is generally well known that little change
of the rotational stiffness has little influence on the mode shapes of plate. However, the current work shows that a very
little change of rotational stiffness value may lead to a large change of the mode shapes of a square plate structure. 相似文献
760.
水面无人船的发展与使命(英文) 总被引:5,自引:0,他引:5