SiC基底HFCVD金刚石薄膜摩擦磨损性能

利用热丝化学气相沉积技术在碳化硅基底上制备微米金刚石薄膜、纳米金刚石薄膜和金刚石–石墨复合薄膜,采用扫描电子显微镜、原子力显微镜和拉曼光谱仪对不同金刚石薄膜的表面形貌和微观结构进行表征,通过摩擦磨损实验测试金刚石薄膜的摩擦系数并计算其磨损率,对比研究不同种类金刚石薄膜的摩擦磨损性能。结果表明：金刚石–石墨复合薄膜具有较好的摩擦磨损性能,薄膜表面粗糙度为53.8 nm,摩擦系数为0.040,和纳米金刚石薄膜(0.037)相当;金刚石–石墨复合薄膜的磨损率最低,为2.07×10^-7 mm³·N^-1·m^-1。在相同实验条件下,同碳化硅基底的磨损率(9.89×10^-5 mm³·N^-1·m^-1)和摩擦系数(0.580)相比,所有金刚石薄膜的磨损率和摩擦系数均有明显提升,说明在SiC基体表面沉积金刚石薄膜能够显著提高碳化硅材料在摩擦学领域的使役性能。     

Data reconciliation and optimal management of hydrogen networks in a petrol refinery

This paper describes the main problems associated to the management of hydrogen networks in petrol refineries and presents an approach to deal with them with the aim of operating the installation in the most profitable way. In particular, the problems of data reconciliation, economic optimization and interaction with the underlying basic control system are reviewed. The paper provides also a proposal for the implementation of the system and illustrates the approach with results obtained using real data from an industrial site.     

Enhancing the performance of exterior waterborne coatings for wood by inorganic nanosized UV absorbers

Enhancing the durability of the architectural wood coatings is essential for a successful commercialization of the forest products. Therefore, this paper is focused on UV resistant waterborne nanocomposites coatings for exterior uses of wood, which were improved with inorganic UV absorbers such as zinc oxide and titanium dioxide nanoparticles. The performance of such nanocomposites coatings applied on black spruce boards was demonstrated trough accelerated weathering. Artificial aging behavior of the coatings was followed by color, gloss and thickness changes. Scanning electron microscopy and transmission electron microscopy was used to investigate nanoparticles dispersion in nanocomposite dry films. Fourier Transform Infrared Spectroscopy was used to characterize the chemical modification of the weathered coatings surface. The results have shown significant improvement in UV-shielding of the nanocomposites coatings. Depending of aging criteria, a selection of the best nanocomposite coatings formulations for exterior wood could be done.     

Pressure and Temperature Field Measurements of a Lightly Loaded Circumferential Groove Journal Bearing

The current study presents the experimental determination of the lubricant film pressure and temperature distributions on one land of a symmetrical two-land circumferential groove journal bearing (CGJB) operating under low-load steady-state conditions. Film pressure and temperature measurements are done both in axial and circumferential directions. Five axial planes, with three equally spaced pressure tappings per plane, construct the base pressure measurements grid. The pressure tappings circumferential location is shifted 20° from one plane to the neighboring plane. Similarly, the base temperature measurements grid consists of four axial planes, with three equally spaced thermocouples per plane. Hence, by rotating the bearing sequentially, with an angular step of 10°, it is possible to create fine measurement grids. This method of measurement is valid, because the circumferential groove journal bearing's operation is independent on the angle of loading. Two supply pressures were considered for the tests. The higher supply pressure leads to a smoother bearing operation. In the diverging zone, subatmospheric regions were measured. Superposing pressure and temperature fields reveals that the maximum temperatures are encountered in the sharp pressure drop region.     

A dynamic rescheduling algorithm for resource management in large scale dependable distributed systems

Scheduling is a key component for performance guarantees in the case of distributed applications running in large scale heterogeneous environments. Another function of the scheduler in such system is the implementation of resilience mechanisms to cope with possible faults. In this case resilience is best approached using dedicated rescheduling mechanisms. The performance of rescheduling is very important in the context of large scale distributed systems and dynamic behavior. The paper proposes a generic rescheduling algorithm. The algorithm can use a wide variety of scheduling heuristics that can be selected by users in advance, depending on the system’s structure. The rescheduling component is designed as a middleware service that aims to increase the dependability of large scale distributed systems. The system was evaluated in a real-world implementation for a Grid system. The proposed approach supports fault tolerance and offers an improved mechanism for resource management. The evaluation of the proposed rescheduling algorithm was performed using modeling and simulation. We present experimental results confirming the performance and capabilities of the proposed rescheduling algorithm.     

Atanassov’s intuitionistic fuzzy grade of hypergroups

This paper deals with connections between hypergroupoids and Atanassov’s intuitionistic fuzzy sets. First a sequence of join spaces is associated with a hypergroupoid H; the length of the sequence is called Atanassov’s intuitionistic fuzzy grade of H. Second, a theorem about the existence of a hypergroup with Atanassov’s intuitionistic fuzzy grade equal to n is proved. Furthermore, some properties of the complete hypergroups in connection with this argument are presented and discussed.