基于DSP的平地机行走智能控制系统设计

国产平地机作业过程完全依靠驾驶员手动控制发动机的油门和挡位,劳动强度大、作业效率低、作业精度很难保证.为了提高平地机的作业效率和作业精度以TMS320LF2407A微处理器为控制核心,采用智能控制技术和CAN总线技术,设计了一种液力机械传动平地机行走智能控制系统,实现了平地机作业过程中的自动换挡和恒速控制.试验结果表明:该系统具有良好的工作稳定性和可靠性.     

PQl90型全液压平地机液压控制系统的设计

本文提出了一种新型全液压平地机液压系统方案，着重介绍了行驶、停车、行车制动、作业四大系统，这些系统中开发与利用了多项具有国际领先的新技术，如PLC速度控制，双管回路、停车制动器、多路阀回路等，解决了原国产机操作困难、因速度控制不当造成熄火、易打滑、难制动、噪声大等许多缺陷，对于提高我国对此方面工程机械液压系统设计有重要指导意义。     

基于Automation Studio铲运机转向液压系统设计

以ACY-6型地下铲运机液压转向系统为研究对象,该系统采用铰接液压转向系统,转向液压系统与工作液压系统采用双泵合流技术,分析该系统的工作原理,并对动作执行机构及所受载荷进行分析,在此基础上,应用Automation Studio仿真软件搭建转向液压系统机械-液压耦合仿真模型,对系统动态工作过程进行仿真,获取了原地转向工况下转向系统与执行机构的特性曲线,为实现该种车辆液压转向系统的优化设计获得理论参考和技术支撑,具有一定的工程应用价值。     

自卸车液压系统对转向系统性能影响分析

为应对自卸车恶劣行驶工况并减轻驾驶员的操作强度,在重型载重汽车上,全液压转向系统得到普遍应用,而液压系统对转向系统性能具有重要影响。根据全液压转向系统的结构特点和性能特征,基于ADAMS搭建转向液压系统和机械机构的分析模型,针对转向、转向盘角阶跃输入、过路障等几种工况进行虚拟试验分析。针对以上工况下,转向系统的响应时间、车辆行驶过程中转向机构所受到的冲击载荷进行分析;并分析系统的结构参数对响应时间和冲击载荷等的影响。由分析结果可知:液压系统使得转向系统反应时间延长;同时,液压系统能够有效地缓冲转向机构受到的冲击载荷。在实际转向液压系统设计中,合理选择转向器与转向动力缸间的液压胶管几何尺寸,使转向液压系统既能有效地吸收车轮遇到的冲击载荷,又不至于严重影响转向系统的响应速度。     

基于负载敏感技术的液压助力转向系统研究

针对传统液压助力转向系统的压力和流量损失问题,设计了基于负载敏感技术的液压助力转向系统。基于仿真软件AMESim对负载敏感泵和液压助力转向系统进行了建模。仿真结果表明:当在直线行驶工况下,该系统以低压、小流量的待机状态输出;当有转向需求时,系统能根据转阀开启阀度,快速调节泵出口的压力和流量,并且能够满足助力需求。基于负载敏感技术的液压助力转向系统在车辆行驶过程中能减小能量消耗,达到节能的目的。     

路面条件对铰接车液压转向系统动态性能的影响研究

为了分析自卸车液压转向系统在车辆运行过程中的性能,采用AMESim/SIMPACK联合仿真方法建立了自卸车液压转向系统的联合仿真模型,进行车辆在不同路面条件下液压转向系统分析,得到油缸位移及压力、车辆转向角的变化过程。可为车辆转向性能的预测提供一种很好的分析方法。     

轮式装载机转向液压系统的振动控制

分析了装载机转向液压系统的工作原理及振动机理,提出了一种基于优化主控制阀节流槽阀口配置控制转向液压系统振动的方法,对装载机转向液压系统中流量放大阀的主阀节流槽阀口进行了全新设计.试验表明,应用新主阀的装载机转向液压系统的振动得到有效控制.     

FW-6型地下工程服务车全液压转向系统设计与仿真

FW-6地下工程服务车是一种井下用铰接式车辆,其转向系统采用全液压转向形式.简要介绍该车转向液压系统的工作原理;提出该车转向液压系统的组成方案,详细阐述该车液压转向系统的设计计算以及关键液压元件的选型;建立该车全液压转向系统的数学模型,利用SIMULINK工具建立其仿真分析模型,并对其进行动态特性仿真.仿真结果表明FW-6地下工程服务车转向液压系统的设计方案是合理可行的.同时,该仿真模型对铰接车辆转向液压系统的设计也具有重要的参考价值.     

全液压转向器数学模型的建立与仿真

在介绍全液压转向器工作原理的基础上，建立了全液压转向系统的数学模型，并利用MATLAB／Simulink仿真工具箱搭建了系统的数字仿真模型，对液压转向系统的静态特性与动态特性进行了分析，并运用传递函数法对液压转向系统的结构特性进行分析，得到了其结构参数对液压转向系统性能的影响规律。     

平地机复合变速系统参数匹配CAD软件的开发

针对平地机液压机械复合变速系统参数匹配计算过程复杂等问题,采用VC++语言开发了一套匹配计算软件.并进行了模拟计算,证明该软件具有实用价值.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。