钻井泵十字头表面耐磨性增强技术及对比分析

钻井泵的十字头易磨损失效,目前主要采用表面改性技术来提高其耐磨性能。针对巴氏合金浇注、电弧喷涂、等离子喷焊和高速激光熔覆4种表面改性技术,从磨损机理、涂层结合强度、涂层材料及质量等技术角度对其进行对比分析。分析结果可为钻井泵十字头的表面耐磨技术评价体系建立及其应用提供参考。     

环氧类玻璃高分子材料的热回收性能研究

采用动态交联技术制备了环氧类玻璃高分子材料（EPV）,将其制得的片材在不同模压条件下进行重复加工,考察了模压温度、模压时间和模压压力对EPV回收材料性能的影响。结果表明：重复加工没有造成EPV回收材料的降解;模压温度越高,模压时间越长,模压压力越大,越有利于EPV的愈合和重塑;在模压温度为180℃,模压压力为20 MPa,模压时间为10 min的较佳条件下,重复加工的EPV回收材料力学性能与初始EPV片材的接近。     

感应式球形电机结构设计与参数分析

针对目前多自由度电机结构复杂,控制难度高的问题,提出一种新型多自由度球形感应电机。该电机由三个空间对称分布的弧面定子驱动球形转子实现多自由度运行。首先,介绍了电机的基本结构和运行原理并对根据直线感应电机的设计理对电机主要参数进行计算;然后,建立Ansoft/Maxwell有限元仿真模型对电机进行稳态磁场仿真;同时对电机在不同转子参数以及不同激励时的稳态运行特性进行分析,为这类电机的优化设计与运动控制提供依据。结果表明:在额定激励下,感应式球形电机单个定子可产生1N·m的稳态转矩,稳定转速可达350r/min,满足多自由度运行要求。     

双电机驱动关节的线性化控制研究

本文基于齿轮传动系统存在的齿隙非线性问题,提出了一种双电机驱动双主动齿轮啮合同一从动齿轮的驱动方案。设计了双电机协调控制算法,包括力矩线性化控制算法与单速度环速度反馈线性化控制算法,解决了电机齿轮传动系统运动过程中的齿隙非线性问题。本文首先介绍了双电机消隙原理与控制方案,然后建立双电机系统控制模型进行分析,最后搭建仿真模型进行控制方案的验证。仿真结果表明,本文所提出的双电机控制方案可以有效地解决齿轮传动中的齿隙非线性问题。     

基于遗传算法与模糊PID复合控制的电机调速研究

为了加强永磁同步电机调速系统的智能控制,提出了一种基于遗传算法与模糊PID智能控制的永磁同步电机调速控制策略。首先建立永磁同步电机的基本模型,利用遗传算法对模糊PID控制器进行改进,优化其参数选择和提高控制效率,并搭建Simulink仿真模型和实验验证模型。其结果得到:利用遗传算法能够迅速得到模糊PID控制器的最佳匹配初始参数,且在电机启动阶段和突加干扰阶段,遗传改进模糊PID控制系统相比于传统的PID控制系统其转速、转矩以及三相电流输出均表现出更加稳定以及波动更小。系统出现干扰后,在该组合智能控制作用下系统在极短时间内恢复稳定,其动态响应速度显著快于传统PID控制方法。结果表明该基于遗传算法与模糊PID控制系统能够对永磁同步调速系统进行有效控制,进而使系统具有较优异的启动特性和动态稳定。     

直流电机电刷磨损预测的粒子滤波方法

针对直流电机电刷磨损的跟踪与预测问题,提出了一种改进型粒子滤波器的电机电刷磨损状态演变预测方法。首先建立直流电机的动态模型,通过电刷磨损仿真分析获得一定时间间隔的电流输出数据,此输出数据作为测量数据用作为预测模型的输入。接着,根据测量数据的变化规律建立电机电刷磨损预测的模型形式,然后通过采用所提出的多项式重采样粒子滤波方法来预测电机电刷磨损状态的演变。案例数据分析结果表明,所提出的基于粒子滤波的电刷磨损预测方法是有效的且计算过程简便。     

变速永磁同步发电机系统稳压控制（连载之五）直接电压控制在发电机系统中的应用

在所研究的具有强弱磁能力变速永磁同步发电机的270V直流电能系统中,应用PWM整流器,提出直接电压控制技术,设计了直流母线电压PI控制器,并结合有源阻尼技术,在Matlab/Simulink仿真及测试平台中加以实现。最后,对本系列连载所研究的各类控制算法的性能进行对比研究。     

Fatigue Delamination Characteristics of Plasma Sprayed Coatings under Fretting

FRETTING is referring to a reciprocating motion withthe small displacement between two components incontact[1].Fretting wear is superficial materialremoval during the fretting.It severely reduces theperformance,efficiency and service lifetime of thecomponents[2],Thermal spraying has been employedto enhance the fretting wear resistance of components,and the fretting wear behavior of the coatings has beenalso explored.However,the experimental results wereoften contradictive and confusing.On …     

Effect of pre-annealing on thermal stability of amorphous Zr-Cu-Ni alloy

The influence of pre-annealing on thermal stability of the amorphous Zr70Cu20Ni10 alloy was reported by em-ploying the differential scanning calorimetry (DSC) and high-resolution transmission electron microscopy (HRTEM) tech-niques. It has been observed that the supercooled liquid region decreases with increasing the annealing time under isothe-mal conditions, indicating that the thermal stability of the amorphous Zr70Cu20Ni10 alloy decreases gradually. HRTEM ob-servations reveal that there exist some ordered atomic clusters in the amorphous matrix at the relaxation stage. These or-dered atomic clusters can be regarded as precursors for the precipitation of the crystalline phases in the subsequent crystal-lization process. The reasons resulting in the decrease in thermal stability of the amorphous Zr70Cu20Ni10 alloy with anneal-ing time are discussed through the Gaussian decomposition for the radial distribution function of the amorphous Zr70Cu20Ni10 alloy.     

Effect of copper addition on the thermal contraction of indium melt clusters

The structure of In-1%Cu and In-5%Cu (mass fraction) alloy melts were studied at different temperatures above liquidus by using a high-temperature X-ray diffractometer and were compared with that of pure In melt. Experimental results show that with the addition of 1% Cu or 5% Cu, the thermal contraction phenomenon of atom clusters occurs in melts with the temperature increasing like pure In melt. With the addition of 1% Cu, the thermal contraction of atom clusters increases and the contraction is not homogeneous in the whole measurement temperature range. The sudden change and noticeable contraction can be found in the range of 280-390℃. The temperature range of the sudden change is lower than that of pure In melt. With the addition of 5% Cu, the thermal contraction of atom clusters decreases and the contraction is not consistent in the whole measurement temperature range. The anomalous change can be measured at about 600 ℃. At the same superheating temperature, the nearest interatomic distance r1 of