底层硬质合金间隔分布自润滑涂层的制备及其摩擦磨损性能研究

为了提高45钢的减摩和润滑性能,选择石墨和YG8硬质合金棒作为电极材料,利用电火花沉积在45钢基体表面制备底层硬质合金间隔分布的自润滑涂层,使用扫描电子显微镜、Image J软件以及EDS对涂层形貌、组成成分进行观察和研究,利用HSR-2M型摩擦磨损试验机进行摩擦磨损试验,分析了相同条件下自润滑涂层、基体和石墨涂层的摩擦磨损性能以及不同条件下自润滑涂层的摩擦磨损性能。厚度75μm、表面粗糙度1.679μm的自润滑涂层均匀、致密,摩擦系数和磨损量相较于基体和石墨涂层明显下降。在载荷为40N和往复摩擦频率为400t/min时,自润滑涂层的摩擦系数最小分别为0.213和0.225。研究结果表明,涂层的耐磨性和润滑性能受底层硬质合金、往复摩擦频率以及载荷的影响,原因是底层硬质合金层不仅能为顶层石墨涂层提供支撑,同时还能与石墨结合生成新的润滑膜,提高自润滑涂层的耐磨性和润滑性。     

环氧树脂复合涂层耐磨性的研究

研究了石墨含量对环氧树脂复合涂层的滚动磨损和冲刷磨损性能的影响。结果表明,随石墨含量的增加,涂层的滚动磨损量减少。在砂粒高速冲刷时,石墨存在反而使耐冲刷磨损性能恶化。随石墨含量增加,低角度冲刷时磨损量增加的更快。     

锡青铜-钢背双金属固体自润滑复合材料的摩擦性能研究

采用粉末冶金工艺制备含石墨固体润滑剂的锡青铜-钢背复合材料,研究了石墨含量对材料的硬度、显微组织和摩擦磨损性能的影响,并考察了摩擦磨损机制。结果表明:在含石墨的青铜-钢背双金属材料中,随着石墨含量的增加,材料的硬度逐渐降低,摩擦磨损性能逐渐改善,但是其显微组织的均匀性也逐渐变差;在石墨含量为3%～5%(质量分数)时,双金属材料既具有较好的摩擦磨损性能,同时表面铜合金层与钢背的黏结强度也很高;随着速度和负荷的增加,材料的摩擦因数降低,磨损增加;摩擦过程中,石墨在摩擦面上成膜是材料具有减摩自润滑性能的主要原因。     

青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能

在MM-200摩擦磨损试验机上研究了青铜-石墨热喷涂层在干摩擦和水润滑条件下的摩擦磨损性能,采用扫描电镜(SEM)对磨损表面形貌进行了观测和采用X射线能谱分析(XPS)分析了涂层成分。结果表明,在水润滑条件下涂层摩擦因数和磨损率均低于干摩擦条件下;在水润滑条件下磨损机制为轻微磨粒磨损和犁削磨损,在干摩擦下主要是较为严重的粘着磨损和犁削。这是由于水润滑降低了摩擦副界面温度,提高了石墨润滑膜的韧性,改善了润滑效果,从而阻止了粘着磨损的发生,水还促进了钢偶件表面致密氧化膜的形成,从而减轻磨损。因此水润滑对涂层磨损性能有较大影响。     

锡青铜基自润滑复合材料摩擦磨损性能研究

采用冷压烧结方法制备了短碳纤维增强锡青铜基自润滑复合材料和ZQSn663锡青铜,对其力学性能及摩擦磨损性能进行了对比研究,并对磨损机制进行了讨论.结果表明,当碳纤维体积分数小于12%时,锡青铜自润滑复合材料的力学性能优于ZQSn663锡青铜,磨损率和摩擦因数低于ZQSn663锡青铜.当碳纤维体积分数达到12%时,复合材料的摩擦磨损性能达到最佳.扫描电镜和EDS分析结果表明,ZQSn663锡青铜的磨损是以粘着和磨粒磨损共存的机制,以粘着磨损为主;锡青铜自润滑复合材料的磨损是粘着磨损和氧化磨损共同作用的结果.     

合金成分和石墨形貌对镍-铁-石墨-硅合金摩擦磨损性能的影响

采用中频感应炉在氩气保护下熔炼制备出不同成分的镍-铁-石墨-硅合金自润滑材料,通过摩擦磨损试验,研究了石墨形貌和合金成分对其摩擦磨损性能的影响。结果表明:在干摩擦和油润滑两种摩擦磨损条件下,材料的摩擦因数均与石墨的面密度相关,石墨的面密度越大,摩擦因数越小,而与石墨的形貌和铁含量无关;材料的磨损率随着材料硬度值的增大而减小,石墨球化后和合金中铁含量的增加均使合金的磨损率大为降低。     

青铜粉对聚四氟乙烯基复合材料摩擦学性能影响的研究

通过向聚四氟乙烯材料加入不同质量比的青铜粉和氧化铅制备了3种自润滑复合材料,并与不加青铜粉的填充氧化铅的聚四氟乙烯材料进行实验研究,研究了青铜粉及其含量对聚四氟乙烯基复合材料摩擦学性能的影响,并探讨了填料的减磨机理。结果表明:在干摩擦条件下,在一定范围内,随着青铜粉含量的增加,填充氧化铅的PTFE基材料的摩擦磨损性能有所降低;在油润滑条件下,填充氧化铅的PTFE基材料的摩擦磨损性能相对干摩擦有所提高,且在一定范围内,随着青铜粉含量的增加,填充氧化铅的PTFE基材料的摩擦磨损性能有所提高;填料的减磨机理与“第三体”有关,而“第三体”又与材料的基体组分有关。     

含碳固体自润滑青铜轴承材料的研制

对青铜－石墨和青铜－碳纤维两种固体润滑轴承材料的物理机械性能及摩擦学性能的试验结果表明：青铜－碳纤维材料具有与青铜－石墨材料相当的摩擦磨损性能和比其更为出色的机械性能：以碳纤维代替石墨加入青铜中。未对摩擦对偶件带来特殊的使用要求；说明青铜－碳纤维有可能成为比青铜－石墨更为优异的新型轴承材料。     

镍包石墨自润滑涂层摩擦磨损性能研究

选用镍包石墨粉末,采用氧-乙炔火焰喷涂技术制备镍包石墨自润滑涂层.在球-盘摩擦磨损试验机上探讨了室温条件下镍包石墨自润滑涂层的摩擦磨损性能.运用扫描电镜、X 射线衍射仪等微观分析手段,对涂层的磨痕表面形貌、磨损颗粒的成分组成及形貌进行了分析.研究发现:镍包石墨自润滑涂层平稳摩擦时的摩擦因数在0.25～0.35之间;开始磨损时,以磨粒磨损为主,严重磨损时以疲劳磨损为主,伴有少量的磨粒磨损.     

热喷涂MoS2/PA(聚酰胺)复合涂层的摩擦学性能及磨损机理研究

利用热喷涂技术在45钢上制备了MoS2／PA(聚酰胺)复合涂层，考察了不同填料含量复合涂层的摩擦磨损性能，采用SEM分析涂层及对偶磨损表面形貌，并探讨了填料对复合涂层摩擦磨损性能的影响机制。结果表明：填料含量大于39／6时，虽然摩擦因数较小，但磨损率很大，且大于纯PA涂层的磨损率；当填料含量小于3％时，涂层摩擦学性能有所提高。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

基于多目标非支配解提取法的电力系统无功优化

针对传统的电力系统多目标粒子群优化算法采用权重系数法将多目标转化为单目标,从而忽视了各目标函数间的竞争关系这一问题,提出将非支配解提取法运用到电力系统多目标无功优化中,并设定了一套提取规则,以电力系统中的有功网损、电压偏差和电压稳定裕度为目标,使目标在充分竞争的情况下得出Pareto最优解,利用IEEE-14节点系统对多目标非支配解提取法的电力系统无功优化进行了仿真测试。研究结果表明,该算法一次运行可以得出多组非支配解,既有偏向单个目标的解也有兼顾所有目标的解,克服了权重系数法的盲目性和单一性,可使电力决策者根据实际问题选择最优解,具有较好的灵活性与多样性。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.