Focused on the abnormal problems of path planning when a custom 6-DOF robot goes passed singular points, this paper makes descriptions based on kinematic analysis and dynamic analysis. It is pointed out that linear interpolation should not be simply abandoned but choose joint motion when singularity problems encounters. Instead, this paper suggests a singularity algorithm to modify the interpolated point sequence in the singular interval after a preliminary path planning of the interpolated point sequences, of which the modification method is called “Bounded Deviation Path Correction Method”(BDPC) in this paper. This algorithm can ensure both the accuracy of the end position and the attitude, and finally realizes the effective and reliable motion planning of the manipulator through the singular interval.

Although the middle position of the O-type 3-position-4-way directional valve with the spool structure is not the working position of the valve, the performance of the middle position is also one of the considerations in the system design. The leakage characteristics of the middle position affect the correctness of the final action of the external load. Leakage effects of the middle position on the action of load under 3 common working conditions were analysed. The results showed that the position of the load actuator moved towards the load direction because of the leakage. The larger the leakage, the faster the response, and the faster the moving speed; the different gaps between different valve ports aggravated the previous phenomenon. The use of a pair of pilot-operated check valves in series and a parallel bypass valve at the inlet and outlet of the actuator could effectively improve the actual cut-off effect of the directional valve.

紫铜管广泛应用于船舶供水海水管路中.通过Ansys流场仿真分析和金相分析,对船舶供水管路弯管处破损原因进行研究.结果表明,在一定范围内启闭阀门时间对弯管处应力和应变影响不大,弯管处存在流速过大现象,存在明显的冲刷腐蚀;通过改进铜管制造工艺、建立管线运行制度控制管路压力冲击、增大管路通径和弯曲半径减小管路冲刷腐蚀都能有效的抑制管路破损.

A superimposed hydraulic back pressure valve with adaptive back pressure was designed. The back pressure of the valve changes as the diving depth of underwater vehicles changes, and is always higher than outboard environmental pressure by an adjustable value, preferred 0.5MPa, to avoid leakage of environmental medium to the inboard hydraulic system. The valve was designed in a pilot-operated style with a flat valve port of main valve. Variable damping plugs were used to easily regulate the dynamic performance of the valve. And an isolation device was adopted to isolate the contact between the inboard and outboard media. The static mathematic models of the valve were established and simulations were carried out. The simulation results show the valve has good pressure stability and flow adaptability, and its back pressure changes with the change of outboard pressure well.

Vehicle cross passages are critical infrastructure for emergency rescue in highway tunnels but how to use them is disputed in the industry. This paper investigates 9 expressway operation and management companies in China and 292 highway tunnels in their charge through site interviews and questionnaires to understand and analyze traffic routes of general vehicles and rescue vehicles and the use of vehicle cross passages during routine operation & maintenance, traffic accident and fire incident handling by each company. The survey results show: it is difficult for large vehicles to pass through vehicle cross passages due to the small radius of turning circle at the corner, and the influence on traffic safety in the adjacent tube is great. It is not recommended to use vehicle cross passages if traffic in the adjacent tube is not interrupted. The use of vehicle cross passages should be limited to rescue vehicles in initial stage of fire incidents.

Mechanical noise is an important part of underwater-radiated noise of naval vessels. With the increasing power of mechanical equipment, the running noise of equipment cannot be ignored. Noise control of ship machinery is mainly carried out in two aspects. One is to control the noise source, and the other is to control the propagation path. The application of vibration isolation device is one of the important measures to control the transmission of mechanical noise. The corresponding natural frequency and mode are obtained through modal analysis, the deformation, impact and other aspects of the vibration isolator are checked, and the stress and strain response of the system under the action of disturbing force is obtained through harmonic response analysis, and the double layer vibration isolation device is tested.

As a kind of widely used industrial equipment for energy exchange, heat exchanger is widely used in daily life. It is a key equipment for heat recovery and is of great significance for energy saving. In this paper, firstly, the heat transfer characteristics of the heat exchanger were analysed. Then the structure, material and performance parameters of the heat exchanger were analysed for the typical titanium alloy shell and plate heat exchanger, and the heat exchanger was checked by ASPEN software. At last, the fatigue analysis under the pressure of 2MPa was carried out for the heat exchanger, and the life, damage, safety factor and fatigue sensitivity curve of the shell plate were obtained, which provides certain reference basis for the structural design and optimization of the heat exchanger.

Six degrees of freedom platform is a kind of space motion simulator, which can complete the simulation of any space motion within its allowed working range. It has been widely used in aerospace, military, automobile manufacturing, entertainment and other fields. The six degrees of freedom platform can simulate the transverse, longitudinal and heave motion of the ship under the influence of ocean environment such as wind, wave and ocean current. In this paper, the composition and structure of six degree of freedom platform are briefly introduced. Then the stress analysis of the key mechanical components of the six degrees of freedom platform shows that the main mechanical components meet the design results. The results of motion interference check show that the structure design is reasonable. Finally, through engineering application and simulation analysis, the control algorithm of six degrees of freedom platform is briefly introduced.

The reciprocating pump has the problem of excessive pulsating pressure due to the inherent characteristics of the equipment, which causes the system to have large vibration and noise in the process of conveying fluid. Aiming at the problem of reciprocating pump pressure pulsation, the solution of reciprocating pump pressure pulsation suppression is put forward in this paper. The comparison test before and after the system improvement shows that the pulsating pressure inside the system has been significantly suppressed, and the pulsating abatement device adopted has a better application prospect.

The characteristics of a pilot-operated pressure-reducing valve for water hydraulics are analysed. The valve operates well with a primary pressure of up to 15MPa, a secondary pressure range of 10MPa to 14MPa, and a flow range of 20L/min to 40L/min. Optimizations are applied to reduce the cavitation noise of the valve and to improve the pressure regulation accuracy of secondary pressure. The first optimization is executed by reducing pressure drop and velocity through the throttle of main spool and the second optimization is carried out by lowering down the steady jet force on both main spool and the pilot spool. The dynamic characteristics of the secondary pressure are obtained by simulations. The results show the valve behaviours better with the improvement structure. The average variation of the secondary pressure is brought down from 0.308MPa to 0.175MPa under different primary pressure conditions and from 0.288MPa to 0.136MPa under different inlet flowrate conditions. The velocity through throttle of the main spool is 31.18% cut down on average.

Copper pipe was widely used in the pipeline of seawater system. Comprehensive characteristics of pipe were analysed. Pressure and velocity were selected as representations of primary static and dynamic characteristics of the pipeline; the breakage reason of water supply pipe was studied through flow field simulation analysis and pipeline metallographic analysis. There was a phenomenon of excessive flow velocity and obvious erosion corrosion in bending pipe; the result showed that erosion corrosion is the direct cause of pipeline breakage. By improving the copper pipe manufacturing press, increasing the pipeline size and bending radius can effectively prevent pipeline damage.

The method of water hammer suppression of the marine moving water system by pump and valves wasstud-ied through transient simulation analysis of Flowmaster. The results show that when the valve is closed rapidly, there is an obvious water hammer in the system. Extend the valve closing time and the two stage closure strategy can be used toeffect-ively suppress the impact of water hammer in the system; the closer of control valve from the pump, the water hammersup-pression effect was better. Pipeline installation of energy storage components can also effectively inhibit the water hammer.

In order to optimize the comprehensive characteristics of a water hydraulic pilot-operated pressure-reducing valve, numerical orthogonal experimental design was adopted. Six parameters of the valve, containing diameters of damping plugs, volume of spring chamber, half cone angle of main spool, half cone angle of pilot spool, mass of main spool and diameter of main spool, were selected as the orthogonal factors, and each factor has five different levels. An index of flow rate stability, pressure stability and pressure overstrike stability (iFPOS) was used to judge the merit of each orthogonal attempt. Embedded orthogonal process turned up and a final optimal combination of these parameters was obtained after totally 50 numerical orthogonal experiments. iFPOS could be low to a fairly low value which meant that the valve could have much better stabilities. During the optimization, it was also found the diameters of damping plugs and main spool played important roles in stability characteristics of the valve.

Comprehensive characteristics of a dynamic flow balance valve of water system were analysed. The flow balance valve can change the drag efficient automatically according to the condition of system, and the effective control flowrate is constant in the range of job pressure. The structure of the flow balance valve was introduced, and the theoretical calculation formula for the variable opening of the valve core was derived. A rated pressure of 20kPa to 200kPa and a rated flowrate of 10m3/h were offered in the numerical work. Static and fluent CFX analyses show good behaviours: through the valve core structure optimization and improve design of the compressive spring, the dynamic flow balance valve can stabilize the flowrate of system evidently. And experiments show that the flow control accuracy is within 5%.

The study has been done with focus on the pneumatic power conversion efficiency by analyzing Perfect Meshing Profile (PMP) correction of the scroll expander with the serious top profile invasion of the inlet port problem in application.The maximal invasion rate reaches 50％,which leads to the increase of inlet air flow friction coefficient.Therefore,on the basis of the circular arc plus line-shaped top profile correction,special correction method for the top profile was proposed.According to the feature of special top profile correction method,it comes to a conclusion that special top profile correction has low invasion rate (the maximum only was 9％) and airflow friction coefficient of the inlet port decreases.In addition,in the intake process,at any time the actual inlet port can remain relatively smoothly,therefore reducing the airstream friction coefficient and the inlet port power loss.And what's more,symmetric synchronous inflation of scroll expander has been accomplished,and consequently the results are smooth power delivery with reducing the mechanical vibration.Theoretically,the scroll expander pneumatic power conversion efficiency has been improved by reducing inlet port inflation power loss.

Hydraulic systems are widely used in industrial applications, but the problem of heating has become an important reason to restrict the promotion of hydraulic technology. The high temperature, will seriously affect the operation of the hydraulic system, even cause stuck and other serious failure. Based on the analysis of the heat damage of the hydraulic system, this paper gives the reasons for this problem, and it is showed by the application that the energy analysis can accurately locate the main reasons for the heating of the hydraulic system, which can give strong practical guidance.

The influence of the compaction period, cement content, and curing period on the strength of solidified soil was studied using an unconfined compressive strength test. The results show that a compaction period that is two long makes the solidified soil more easily compacted, but causes a loss of the cementing strength. According to mechanism analysis, it is found that the strength of the remolded solidified soil is related to the dry density of the sample, and a linear equation is fitted to test data. Based on the test results, it is recommended that solidified soil be used as soon as possible after mixing so as to make full use of cementation of cement. Otherwise, it is necessary to improve the degree of compaction in order to achieve the design requirements.

In order to improve the sealing reliability of the lead wire from the pressure chamber in the high pressure environment and ensure that the electronic equipment used in the downhole tool can work under atmospheric pressure,a kind of inj ection class high pressure sealing connector was designed.The sealing connector which filled with rubber and epoxy resin was analyzed based on the finite element software,and the experimental verification was carried out.Analysis and experiment results showed that when the filling material was rubber,the sealing property was good,but the material was easy to be squeezed out,and 88°was a better choice for the semi-cone angle of shell body.When the filling material was epoxy resin,material protrusion could be avoi-ded,but there would be liquid leaking in a certain pressure range.When the filling material was rubber and epoxy resin,evagination distance decreased with increasing of epoxy resin and the use ratio of epoxy resin 40% was a good choice.High pressure sealing connector mainly relied on first five threads to bear load.The maximum stresses appeared at the minor diameter between first thread and second thread of shell body.The maximum stresses of contact pin appeared at the upper border between rubber and epoxy resin.The researching achievement has certain signifi-cance for design of high pressure sealing connector and selection of filling material.

针对中国大型火电机组小汽轮机排汽连接方式存在的问题进行相应的改进,提出改进后的热经济性计算方法.以国产600 MW超临界机组为例,应用热力系统简捷计算法和等效热降法对改进后的小汽轮机排汽连接系统进行定量计算.研究结果表明,小汽轮机排汽连接方式改进后能有效地提高电厂机组运行的经济性.