基于状态观测器的不确定时变时滞系统的H∞控制

研究一类不确定时变时滞系统基于状态观测器的H∞控制问题用线性矩阵不等式(LMI)方法设计出线性动态输出反馈控制器,闭环系统从扰动输入到受控输出之间传递函数的H∞范数不大于给定的指标值γ.数值实例及仿真结果表明了该方法的有效性和可行性.     

高压大功率器件用6 kV/180℃高温反偏测试装置研制

高温反偏测试(hightemperaturereversebias,HTRB)作为功率器件可靠性测试的重要环节,其测试装置的精度和功能决定了对被测器件老化程度判定的准确性.针对高压大功率器件对测试装置空间、精度以及可靠性的需求,自主研制出了电压等级6 kV、环境温度180℃的高温反偏测试装置.此外,该测试装置还集成了温...     

地面目标与背景的红外辐射对比度特性

红外系统对处于地面背景中的目标探测,很大程度上取决于目标本身与周围背景之间的红外辐射特征差异,即两者之间的辐射对比度。简要讨论了辐射对比度与目标发射率及目标背景温差的关系。分析了影响地面建筑物及水泥地面温度的各种因素,建立了基于一维有限差分法的计算温度的模型并利用MATLAB得以实现。计算了目标与背景在8~14 ?滋m波段上的红外辐射对比度。结果表明在不同情况下同一目标与背景的红外辐射对比度变化较大,不同方位墙面与背景的对比度具有不同的变化趋势。     

浅论市政施工企业的集约化项目管理

近年来我国经济增速放缓,基础建设领域投资规模下降,市政工程施工行业市场竞争更加激烈,工程项目施工利润越来越薄,为应对市场形势的变化,市政施工企业转变以往单纯依靠规模效益求发展的粗放型经营管理方式已势在必行。实施集约化项目管理,是施工企业经营管理全面转型升级的一种有效途径和方式。笔者从市政工程项目管理工作实践出发,阐述了市政施工企业集约化项目管理方面的一些观点和看法。     

国产催化剂在50dam3/h制氢装置中的应用

介绍了国产催化剂HP-3,JX-5A,JX-4C,Z417/Z418和KBL-101在中国石油天然气股份有限公司锦西石化分公司50 dam3/h制氢装置的首次组合应用情况,并针对装置的设计和实际的操作条件、产品质量和总能耗等方面进行了对比分析.结果表明:①该氢气设计纯度为99.90％(摩尔分数),而实际纯度为99.56％,比设计值低0.34百分点,实际产品中甲烷与氮气的摩尔分数比设计值略高0.34百分点,一氧化碳与二氧化碳的实际值比设计值低,说明变压吸附过程设计合理;②制氢设计总能耗为55 083.2 MJ/t,实际总能耗47 224.6 MJ/t,两者相差不大,其中燃料气单耗占制氢装置总能耗比例较大,而实际燃料气单耗比设计燃料气单耗低7 858.6 MJ/t.该装置实际生产参数与设计参数一致,装置设计合理,满足生产要求.     

Graphene nanosheets-poly(o-aminophenol) nanocomposite for supercapacitor applications

Graphene nanosheets-poly(o-aminophenol) (POAP/GNS) nanocomposite was fabricated on a platinum surface by potential cycling. Voltammograms of the POAP/GNS/Pt electrode showed an excellent capacitive behavior accompanied with a redox transition with a mid-peak potential of 295 mV. The POAP/GNS nanocomposite displayed a specific capacitance as high as 281.1 F g⁻¹ at 0.1 A g⁻¹ which is almost three times higher than that of pure graphene. The specific energy and power of the nanocomposite material were 25.0 Wh kg⁻¹ and 34.8 W kg⁻¹, respectively. The nanocomposite retained more than 99% of the initial capacitance after 1200 charge/discharge cycles.     

真空钙热还原法制备金属钛粉的研究

在真空炉中(30~40 Pa)1273 K下,将物料放入螺纹密封的石墨坩埚中进行不同时间下的还原反应。本文采用热力学分析及X射线衍射、扫描电子显微镜及能量弥散X射线谱等方法与手段,系统研究了金属钙(Ca)与反应器中的氧气(O2)、氮气(N2)、二氧化钛(TiO2)的反应和还原时间及还原产物的预处理对得到金属钛粉(Ti)的影响。通过热力学研究,在温度低于钙的熔点(1115 K)时,密封容器内的O2与Ca的反应及N2与Ca的反应满足反应发生的热力学条件。当温度达到1273K时,Ca的饱和蒸气压p*≈p系,有利于整个气固反应进行。实验研究表明,在还原反应发生前,反应器内的O2,N2与Ca反应完全。将在1273 K下还原时间为4 h得到的还原产物在酸洗前真空挥发处理还原产物表面大量的Ca时,金属单质Ti再次被氧化成低价氧化物,最终得不到金属Ti粉。将反应时间延长至6 h时,酸洗过滤后得到形状不规则、纯度达到98.64%的Ti粉。     

供电辅控设备的研制

燃气轮机发电机组返厂维修期间,供电辅控设备对整个动力系统的功能进行补充,保证了系统全年不间断工作的需求。供电辅控设备的散热能力关系到电气部件良好的传热性能和可靠性,根据散热要求,计算得出进风口临界面积为42 cm2,实际设计为121 cm2,满足设备散热要求。整套设备的控制系统由单片机及其接口电路组成,采集器将数据采集信息处理程序软件固化在存储器内,通过控制器实现指令的接收与传递。整套供电辅控设备机电一体化程度高,提高了动力系统缺少燃气轮机发电机组时的工作能力及稳定性。     

Structural Analysis of Cold-Sprayed Nickel-Based Metallic and Metallic-Ceramic Coatings

Powder type and composition have a very important role in the production of metallic and metallic-ceramic coatings by using the low-pressure cold spray process. Furthermore, structure and mechanical properties of Cu and Cu + Al₂O₃ coatings are strongly influenced by powder characteristics of Cu particles. The aim of this study was to evaluate the effect of different particle types of Cu powder and different compositions of added Al₂O₃ particles on the microstructure, fracture behavior, denseness, and mechanical properties, i.e., hardness and bond strength. Spherical and dendritic Cu particles were tested together with 0, 10, 30, and 50 vol.% Al₂O₃ additions. Coating denseness and particle deformation level increased with the hard particle addition. Furthermore, hardness and bond strength increased with increasing Al₂O₃ fractions. In the comparison between different powder types, spherical Cu particles led to the denser and less oxide-contenting coating structure due to the highly deformed particles.     

Digital twin-based framework for wireless multimodal interactions over long distance

Wireless multimodal interactions over long distance (WMILD) would give rise to numerous thrilling applications, such as remote touching and immersive teleoperations. However, long distances can induce large propagation delays, which makes it difficult to meet the ultra-low latency requirements in haptic-visual interactions. Considering existing works mainly focused on the wireless access part, this paper designs an end-to-end framework for general WMILD applications based on the digital twin (DT) technology and proposes an intelligent resource allocation and parameter compression scheme to guarantee WMILD performance under constraint network resources. In the framework, user device can acquire real-time remote interactions by performing local interactions with nearby base station (BS), where a DT of the remote side is deployed to predict the remote haptic-visual feedbacks. A reliable DT updating process is carefully designed to guarantee the DT accurately model its dynamic physical counterpart. To optimize the updating reliability, we formulate the resource allocation and parameter compression to be a constraint-Markov decision problem, under the constraints on energy consumption, multimodal interactions and updating latencies. Then, a safe deep reinforcement learning algorithm is proposed to adapt resources and compression according to the dynamic DT updating workload, multimodal data-streams and remote transmission capacities. Simulation shows the framework can achieve high updating reliability compared with baselines.