城市配网自动化可靠性评估与成本效益分析

实施城市配电网自动化是提高电力系统可靠性的重要技术手段。论述配网自动化技术的机理和特点,探讨配网自动化对可靠性的影响,并对传统的配电网可靠性评估方法进行修正,建立配网自动化可靠性评估模型;通过成本效益分析法,分析配网自动化的经济效益;最后,以某实际配电系统为例验证评估方法的综合效果以及成本效益间的经济性关系。实施配网自动化改造可有效提高其可靠性和经济效益。     

On the Survivability of Self-repairing Control System for a Hybrid Underwater Vehicle

A hybrid remotely operated underwater vehicle （HROV） capable of working to the full ocean depth has been developed. In order for the vehicle to achieve a certain survivability level, a self-repairing control system （SRCS） has been designed. It consists of two basic technologies, fault diagnosis and isolation （FDI） and reconfigurable control. For F＇DI, a model-based hierarchical fault diagnosis system is designed for the HROV. Then, control strategies which reconfigure the control system at intervals according to information from the FDI system are presented. Combining the two technologies, it can obtain the fundamental frame of SRCS for the HROV. Considering the hazardous underwater environment at the limiting depth and the hybrid operating modes, an assessment of the HROV＇ s survivability is vitally needed before it enters operational service. This paper presents a new definition of survivability for underwater vehicles and develops a simple survivability model for the SRCS. As a result of survivability assessment for the SRCS, we are able to figure out the survivability of SRCS and make further optimization about it. The methodology developed herein is also applicable to other types of underwater vehicles.     

高职院校学生党建工作与就业工作契合研究

大学生就业是民生之本,是关乎社会和谐稳定的"民心工程",也是关乎高职院校生存和发展的"生命线"。高职院校人才培养工作就是要以就业为导向,不断提升学生的就业竞争力,培养能够满足社会生产第一线需要的实用技能型人才。党建工作作为人才培养工作的重要组成部分,应与就业工作有效契合,实现彼此间的相互促进,构建两者双赢新模式,为两者的工作思路带来更加广阔的发展空间。     

基于资源分布规律的信息系统风险量化模型

为了实施信息系统的风险度量,首先基于信息流的资源分布规律,参考风险评估要素改进模型,得到具有体系性和完整性的风险分布;在获取风险分布后,基于资源保护角度,考虑安全保护等级,运用层次分析法、多级模糊综合评判、函数级数展开、F-统计量等方法和工具对资源的安全属性所面临的风险进行量化,给出系统的风险量化指标体系,重点考虑风险之间的相关性,构建相关性准则,并得到其计算量为o(Si)。     

Electromagnetic wave absorbing properties of Cr2AlB2 powders and the effect of high-temperature oxidation

The electromagnetic (EM) wave absorbing properties of Cr₂AlB₂ powders and those after high-temperature oxidation were investigated. Coupling of magnetic and dielectric loss enables Cr₂AlB₂ with good absorption properties. The minimum reflection loss (RL) value is −44.9 dB at 8.5 GHz with a thickness of 2.7 mm, and the optimized effective absorption bandwidth (E_AB) is 4.4 GHz (13.0-17.4 GHz) with a thickness of 1.6 mm. After oxidation at 750, 900, and 1000°C for 2 h, the minimum RL values, respectively, are −23.9 dB (17.5 GHz, 1.5 mm), −41.4 dB (16.5 GHz, 1.5 mm), and −39.5 dB (8.0 GHz, 3.0 mm); and the corresponding E_AB values, respectively, are 3.8 GHz (13.6-17.4 GHz, 1.7 mm), 4.1 GHz (13.5-17.6 GHz, 1.6 mm), and 4.4 GHz (13.0-17.4 GHz, 1.7 mm). With an absorber thickness of 1.5-4.0 mm, the E_AB with a RL value of less than −10 dB can be tuned in a broad-frequency range 5.0-18.0 GHz, which basically covers C (4-8 GHz), X (8-12 GHz), and Ku (12-18 GHz) bands. These results demonstrate that Cr₂AlB₂, as a high-efficient and oxidation-resistant absorber, is a promising candidate for microwave absorption applications and can retain good EM wave absorbing properties after high-temperature oxidation.     

基于射钉法的小方坯凝固过程数值模拟

结合方坯连铸机二冷各段的实际情况，在二冷各段末对铸坯进行射钉取样，利用硫印法测定方坯二冷区内目标点凝固壳的厚度，建立了方坯传热数学模型，并利用射钉结果修正数学模型中的各段的传热系数，提高数学模型的准确性。将射钉法确定的坯壳厚度与数学模型计算结果相比较，结果表明，利用修正过的数学模型可以模拟整个铸机的传热凝固过程。     

奥氏体耐热不锈钢310S的抗高温氧化性能研究

采用增重法研究了奥氏体耐热不锈钢310S在700、900和1000℃空气中高温氧化动力学,并结合X射线衍射(XRD)、扫描电镜(SEM)及能谱分析(EDS)等手段,对氧化膜的形貌和组成进行了分析。结果发现,700℃时氧化速率比较稳定且氧化增重较小,其余温度下氧化增重较大且遵循抛物线规律。该钢中Cr在高温时容易形成FeO·Cr2O3、FeO·Fe2O3和尖晶石结构(FeCr2O4,NiCr2O4)等保护性氧化膜,是310S钢具有良好的抗高温氧化性能的重要原因。     

利用变频调速器对砂布砂纸生产线进行恒张力控制

本文根据弹性力学中的虎克定律，结合砂布砂纸生产特点，分析计算了生产线中基体、应变、速度、张力、转速等参数之间的关系，建立了砂布砂纸生产线中传动辊转速（频率）运动方程。然后利用此规律通过交流变频调速器对电机转速的控制，实现了砂布砂纸生产线的恒定张力控制。系统控制简捷、稳定，调节方便，节约能耗，重复性好，实用性强。     

几种行之有效的液压系统故障诊断方法

给出了大型装备液压系统故障诊断的一般步骤,列举了直接诊断法、原理诊断法、因果图法等几种实用的故障诊断方法。