高强混凝土框架节点单向荷载的有限元分析

论述了单调荷载下高强钢筋混凝土框架节点的非线性受力性能。高强混凝土选用基于等效单轴应变的增量式正交异性混凝土模型，及高强混凝土单轴受力下的应力-应变关系．钢筋应力-应变关系采用了弹塑性模型，高强混凝土和钢筋之间采用双垂直弹簧模型，编制了二维非线性有限元分析程序，并用此程序计算了在单调荷载下的这4个高强混凝土框架节点试件屈服荷载、极限荷载并绘出骨架曲线，计算结果与试验结果吻合较好。     

基于多反馈环结构提高硬件储备池记忆能力

针对单反馈环硬件储备池记忆能力不足的问题,提出一种基于多反馈环结构提高储备池记忆能力的方法.通过增加反馈环将更早输入信号产生的响应重新注入回储备池,使更早期的输入信号也影响储备池的内部动态,从而增强储备池的记忆能力.仿真研究了单个和多个反馈环结构的储备池的记忆能力及其在需要更长记忆能力的NARMA30任务中的预测性能.结果表明,把反馈环增加到10个,虚节点数为50时储备池的记忆能力由单反馈环的18.2提高到40.2.仅用两个反馈环,虚节点数为1000时NARMA30预测的归一化均方根误差可从单反馈环的0.27降到0.09.说明通过合理设置多个反馈环的参数,可以设计出任务需要的特定记忆能力,部分解决了储备池的适应性问题.     

高性能混凝土剪力墙抗震性能的试验研究

基于低周循环荷载下聚丙烯纤维高性能混凝土剪力墙的试验结果,研究了高性能混凝土剪力墙的抗震性能,并得出了一些有益的结论。最后,就高性能混凝土的剪力墙抗震设计提出了一些建议。     

基于阵列漏磁信号分析的无刷直流电机高阻接触故障诊断研究*

无刷直流电机具有效率高、能量密度高、噪音低等优点进而被广泛应用于汽车、工业自动化、航空航天等领域。高阻接触（high resistance connection, HRC）故障是电机的典型故障之一,该故障严重时会导致急剧温升乃至火灾,因而无刷直流电机的HRC故障研究具有重要的意义。通常采用电流电压信号分析的方法诊断HRC故障,但现有的方法仍存在局限与不足。针对此问题,设计了一种新的结合阵列漏磁信号分析和机器学习的方法实现无刷直流电机HRC故障的定位和定量分析。首先通过安装在电机外壳的霍尔传感器阵列采集多通道漏磁信号,利用神经网络分析漏磁信号的时域特征实现电机HRC故障检测和定位。在确定故障相之后,利用另一个神经网络模型分析漏磁信号频域特征实现HRC故障的定量分析。实验结果表明,提出的方法检测和定位故障的精度为9875%,故障定量分析的平均均方根误差为0018 Ω。该方法具有非侵入式测量、易于实现、效率高等优点,对提升无刷直流电机HRC故障检测精度和效率具有促进作用。     

Intelligent assistance for older adults via an admittance-controlled wheeled mobile manipulator with task-dependent end-effectors

The increase in the ageing population worldwide poses a severe challenge in assisting older individuals to live independently, including the provision of mobility assistance and support in daily activities. In this paper, a practical robotic system is developed to provide intelligent support for older persons using a wheeled mobile manipulator (WMM), consisting of an omnidirectional mobile platform and a robotic arm. We focus on two critical needs: (1) mobility assistance, and (2) object manipulation support. The tasks are not executed simultaneously and each uses a task-dependent end-effector. Learning from demonstration, or kinesthetic teaching, is adopted to help the WMM to learn an elderly or disabled user’s walking pattern or an able-bodied person’s object manipulation skill. The robotic system can assist the user in conducting a number of daily operations. For mobility assistance, the WMM is reconfigured into a smart walker, where a novel variable admittance control is adopted to detect the user’s walking intention. A learning approach based on dynamic movement primitives is implemented to capture and adapt the WMM to the user’s walking pattern. For object manipulation support, a demonstrator first collaborates with an elderly user to conduct the task, and then the WMM takes the role of the demonstrator to assist the user. The Gaussian mixture model and Gaussian mixture regression are used to learn and reproduce the demonstrator’s experience, respectively. The advantages and effectiveness of the proposed approach are experimentally demonstrated with a four-wheel omnidirectional WMM.     

洛氏硬度计的稳定性检测

使用数理统计的方法研究了洛氏硬度计HRC和HRB两种标尺的硬度检测结果的稳定性。结果表明:洛氏硬度计的HRC标尺运行平稳可靠,可满足进出口金属材料的日常检测需求,而HRB标尺的稳定性相对较差;对于检验业务繁忙的实验室,建议在两台硬度计上分别检测HRC和HRB两种硬度,或加强期间核查和计量的频次,确保硬度计的稳定性。     

Optimization of wear and friction characteristics of Phyllanthus Emblica seed oil based lubricant using response surface methodology

The escalating prices, rapid diminution of fossil fuels, tenacious regulations of the authorities, etc. enforced towards the alternate biogenic fuel for lubrication. The present study assessed the lubricity characteristics of Phyllanthus Emblica seed oil based lubricants by using a pin on disc (POD) tester. The design of experimentations has been carried out using response surface methodology (RSM). The value of parameters such as blend ratio, load and sliding speed ranges from 0 to 20%, 50 to 100?N and 1.3 to 3.8?m/s, respectively, are used to assess the value of specific wear rate (SWR) and coefficient of friction (COF). Test results illustrate that the adhesive wear occurred during the experiments. It has been observed that AB10 shows the probable results in terms of wear and friction characteristics as compared to other lubricant variants at low load and high sliding velocity conditions and perform as an excellent lubricant additive. This contributes towards the replacement of petroleum based lubricants. Analytical ferrography and total acid number (TAN) analysis of the used oil was also done to study the wear debris in the oil.     

烧结钢洛氏硬度HRC与孔隙度的关系

阐述了烧结钢硬度测试的特点,建立了基体洛氏硬度与其表观硬度和孔隙度的函数关系,并做了实验验证,最后进行了分析与讨论。     

热轧卷板开平板在直缝埋弧焊管中的应用

介绍了热轧卷板开平板和中厚板的区别,阐述了热轧卷板开平板生产直缝埋弧焊管的难点,并提出了解决难点的有效措施。通过介绍巨龙钢管有限公司用热轧卷板开平板生产的直缝埋弧焊接钢管的情况,指出国内企业采用热轧卷板开平板和JCOE工艺生产管线用直缝埋弧焊管是可行和可靠的,同时也增加了制管企业在钢板原料上的选择空间。     

Microform Calibration Uncertainties of Rockwell Diamond Indenters

National and international comparisons in Rockwell hardness tests show significant differences. Uncertainties in the geometry of the Rockwell diamond indenters are largely responsible for these differences. By using a stylus instrument, with a series of calibration and check standards, and calibration and uncertainty calculation procedures, we have calibrated the microform geometric parameters of Rockwell diamond indenters. These calibrations are traceable to fundamental standards. The expanded uncertainties (95 % level of confidence) are ±0.3 μm for the least-squares radius; ±0.01° for the cone angle; and ±0.025° for the holder axis alignment calibrations. Under ISO and NIST guidelines for expressing measurement uncertainties, the calibration and uncertainty calculation procedure, error sources, and uncertainty components are described, and the expanded uncertainties are calculated. The instrumentation and calibration procedure also allows the measurement of profile deviation from the least-squares radius and cone flank straightness. The surface roughness and the shape of the spherical tip of the diamond indenter can also be explored and quantified. Our calibration approach makes it possible to quantify the uncertainty, uniformity, and reproducibility of Rockwell diamond indenter microform geometry, as well as to unify the Rockwell hardness standards, through fundamental measurements rather than by performance comparisons.