基于MMS替代协议的变电站安全通信技术研究及应用

目前,绝大多数变电站基于IEC61850标准建设,站内通信协议主要包括制造报文规范(MMS)、面向通用对象的变电站事件(GOOSE)、采样测量值(SMV)等,在工程应用实践中逐渐暴露出一些不足与安全隐患.为此,基于MMS替代协议,重点介绍了其实现的功能与安全防护技术.在功能方面,MMS替代协议增加了多个服务,并优化了现有MMS协议的不足;在安全防护技术方面,MMS替代协议的应用层实现了基于SM2算法与调度证书的双向身份认证,杜绝未授权设备的非法接入、攻击,从协议源头杜绝设备连接的不安全性;MMS替代协议的传输层实现了基于SM2算法与调度证书的全链路加密、认证,确保传输数据报文防伪造、防抵赖、防窃取,保护数据报文的机密性、完整性.测试结果表明MMS替代协议在工程应用中具有一定的参考意义.     

小波分析与漏磁检测信号处理

详细介绍了小波分析的基本理论,并将其引入到钢管漏磁探伤信号的分析中,可以去除噪声、压缩数据和检测奇异性,而且为缺陷的定性和定量分析提供了新的判定方法.     

Matching ultrasonic transducer using two matching layers where one of them is glue

The aim of this work is to propose an original solution to the acoustic impedance mismatch between a PZT transducer and a water load. The characteristic acoustic impedance of the PZT is around 33 MRayl. Theoretically, a quarter-wave layer with characteristic acoustic impedance equal to 7 MRayl is necessary to match the transducer to water. In practice, it is difficult to find a material with this particular impedance. Two or more quarter-wave layers may also be used. The following proposed solution consists in using two matching layers where one of them is the glue. Moreover, their thicknesses are not equal to a quarter of their individual wavelength. Once the glue is taken as the first matching layer, the specific material of the second layer can easily be found. In this work, the second layer, which is also the front layer, is made of glass. The thickness of each matching layer is then calculated as a function of the characteristic acoustic impedance of the two layers. The influence of the thickness of these layers is discussed. The proposed matching configuration is analyzed and theoretical results have been carefully and successfully compared with measurements.     

The Structure of the Irreversibly Bound Adhesion Promoter-Substrate Interfacial Layer of γ-Aminopropylsilanetriol on Crystalline Si, as Measured by XPS and FTIR

The irreversibly bound interfacial layer deposited by the γ-aminopropysilanetriol adhesion promoter onto a crystalline silicon substrate, which remains even after profuse washing, was found by XPS to have resulted from the fragmentation and rearrangement of the original γ-aminopropylsilanetriol molecule. A mechanism is proposed, involving the homolytic scission of the terminal N-C bond. One of the subsequent reactions is believed to involve hydrogen loss by abstraction and the formation of a terminal vinyl group, which bonds to the substrate. Support for this mechanism is found in IR spectroscopy of this layer.     

Factors influencing the formation of elongated morphologies in immiscible polymer blends during melt processing

The morphology of the dispersed phase in immiscible polymer blends plays an important role in the determination of the final physical properties. This paper considers factors that influence the final state of deformation of the dispersed phase, and in particular, the formation of fibers and lamellae. Blends of polyethylene and nylon-6 were extruded by ribbon extrusion at different draw ratios. Prior to single-screw extrusion the materials were blended in a co-rotating twin-screw extruder, and the size of the dispersed phase was studied as a function of the viscosity ratio. As the blends are extruded into ribbons and drawn through the calender rolls, the morphology of the dispersed phase undergoes drastic transformations. The fiber formation is enhanced by increasing the draw ratio. At high draw ratios, long thin fibers are observed. Some biaxial deformation is obtained for the noncompatibilized systems when the extruded materials enter the calender with the maximum closing pressure applied to the rolls. The same effect is observed for the compatibilized systems with lower values of the viscosity ratio. As a general rule, it has been observed that the final dispersed phase deformation is diminished in interfacially compatibilized systems.     

EXPERIMENTAL STUDY ON MIXING: POWER CONSUMPTION AND DEGREE OF SUSPENSION

An experimental study on mixing, degree of suspension and power consumption in solid-liquid suspensions was done. A system similar to those found in anaerobic fermentation processes of animal manures was used, and an existing mixing equipment was adapted for the study. Power consumption and degree of suspension for both mechanical mixing and mixing by gas was determined. The influence of variables such as geometry, solids concentration, stirrer velocity, and gas velocity was studied, discussed, and compared to data from the literature. Best results were obtained for gas mixing, the power consumption being about one fourth of that required by mechanical agitation. Finally, extended correlations relating Power and Reynolds numbers for mechanical mixing and mixing by gas are proposed.     

共沉淀法制备三元系铋基焦绿石型陶瓷粉体

采用改进的Mergen A．方案，用氧化锌、三氧化二铋、三氧化二锑为原料，氨水、草酸铵和碳酸铵分别为沉淀剂，盐酸为溶剂，用共沉淀法成功制备了亚微米级颗粒、高活性的铋基Bi1.5ZnSb1.5O7（BZS）焦绿石型介电陶瓷粉体。探讨了用不同的沉淀剂、在不同的烧结温度所得产物的形态。结果表明氨水做沉淀剂在570℃就可生成纯的焦绿石结构。与Mergen A方法相比成本大大降低，可以使瓷片组织的均匀性提高，电性能得到改善，电压梯度下降。     

釜式内电解法处理高浓度制药废水

提出了釜式内电解的方法 ,成功解决了以往塔式内电解中铁屑结块问题。研究了釜式内电解的最佳工艺条件。用该法对实际高浓度制药废水进行了处理 ,可生化性明显提高     

Decentralized observers with consensus filters for distributed discrete-time linear systems

This paper presents a decentralized observer with a consensus filter for the state observation of discrete-time linear distributed systems. Each agent in the distributed system has an observer with a model of the plant that utilizes the set of locally available measurements, which may not make the full plant state detectable. This lack of detectability is overcome by utilizing a consensus filter that blends the state estimate of each agent with its neighbors’ estimates. It is proven that the state estimates of the proposed observer exponentially converge to the actual plant states under arbitrarily changing, but connected, communication and pseudo-connected sensing graph topologies. Except these connectivity properties, full knowledge of the sensing and communication graphs is not needed at the design time. As a byproduct, we obtained a result on the location of eigenvalues, i.e., the spectrum, of the Laplacian for a family of graphs with self-loops.     

The morphology of MoS2, WS2, Co–Mo–S, Ni–Mo–S and Ni–W–S nanoclusters in hydrodesulfurization catalysts revealed by HAADF-STEM

HAADF-STEM studies have provided detailed morphological insight regarding MoS₂, WS₂, Co–Mo–S, Ni–Mo–S and Ni–W–S nanostructures in graphite-supported catalysts. It is found that the technique allows the catalytically active edges to be imaged even for single layer metal sulfide structures. Unpromoted MoS₂ and WS₂ are predominantly present as slightly truncated triangular clusters containing only a single S–M–S layer (M = Mo, W). The addition of promoter atoms results in more heavy truncations consistent with the expected tendency for the Co–Mo–S structures to expose promoted S-type edges at the expense of unpromoted Mo-type edges. However, the HAADF-STEM (High-Angle Annular Dark-field Scanning Transmission Electron Microscopy) results show for the first time that Co–Mo–S and Ni–W–S may also expose extended high index truncations.