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The basic structure,types,properties and future research directions of polyamide thermoplastic elastomer are reviewed,and the synthesis method of polyamide thermoplastic elastomer is emphasized. The synthetic methods of polyamide thermoplastic elastomers mainly include the following: dibasic acid synthesis method, isocyanate synthesis method, anionic polymerization synthesis method, one-step synthesis method, transesterification method, dynamic vulcanization process. For each synthesis method, the existing problems are explained separately, and solutions to the corresponding problems are proposed. As a new type of thermoplastic elastomer, polyamide elastomer has excellent physical and chemical properties, such as good flexibility, high tensile strength, high low-temperature impact resistance, chemical resistance and weather resistance, and easy processing molding, applicable to various fields, is a major mainstream of thermoplastic elastomers in the future. At present, my country's demand for polyamide elastomers is increasing year by year,but the domestic industrialization of the elastomers has not yet been popularized. Therefore, it is of great value to develop a green, environmentally friendly and industrialized synthetic process in the future. [ABSTRACT FROM AUTHOR]

Valve-closing analysis is used to obtain the optimal valve-closing scheme in maintenance of water distribution networks, which is significant for water supply security. A new pipeline analysis model, unit-valve graph, is presented based on the traditional node-link graph model, which has much less features and concise topology. As a pseudo-dual graph of the original node-link graph, the unit-valve graph classifies the network regions isolated by valves as vertexes, and takes valves as edges. An efficient isolated unit constructing algorithm is designed based on the node-link graph, which helps to build the unit-valve graph. Further more, an efficient valve closing algorithm based on the unit-valve graph is developed. Experimental results show that the new algorithm has a remarkable advantage in terms of efficiency compared with the traditional algorithm and get a correct valve closing scheme even in the case of multi point construction. [ABSTRACT FROM AUTHOR]

Currently, many universities are using traditional manual way to purchase reagents and consumptive materials, which cause long procurement cycle and high procurement costs. Therefore, it is necessary to centralize procurement of reagents and consumptive materials with the help of network. From innovating traditional procurement mode and improving procurement management, using the method of centralized bidding and e-commerce procurement, we can shorten procurement cycle, reduce procurement costs, and achieve maximum benefit. The centralized procurement network of reagents and consumptive materials which according to centralized procurement management process of universities has established a management information system and centralized procurement system. The user orders online goods and setting the time and place of delivery that can reduce the cost of procurement and improve purchasing efficiency, avoid all sorts of integrity risk and also provide data for users to use reagent consumables, then the reagents and consumptive materials purchase, use and disposal can be scientific, networked and fine management. [ABSTRACT FROM AUTHOR]

To resolve the difficult problem of soft tissue segmentation of MRI images of the segmentation of the multi target region of interest in the MRI images with complex targets and fuzzy boundary, this paper proposed a novel MRI image segmentation method, based on anisotropic diffusion and spatial fuzzy C-means clustering (SFCM). It preprocessed the images using the nonlinear and anisotropic diffusion, resolving the problem of weakening the image details while removing the noise. It designed space function combining with the neighborhood space, improving traditional FCM objective function. It used the spatial information of the image to achieve the accurate classification of every object in image was an effective solution to the isolated area correctly classified. After that, it obtained complete and continuous segmented regions. Finally, it utilized the fitting curve of histogram to initialize the classification number and the initial cluster centers, accelerating the algorithm iterative to the optimal solution, and also reducing the run time. The experiments show that the possibility of find a best solution is improved by introducing the method of MRI image segmentation method based on anisotropic diffusion and spatial FCM, so as to the processing of MRI images segmentation which has overlapped grayscale, discontinuous objects and fuzzy boundary. [ABSTRACT FROM AUTHOR]

To improve predicting accuracy further, this paper modified original Pareto dominance relation among the candidate solutions, and proposed a new method named d-Pareto dominance prediction using nearest neighbor. Combined with the characteristics of multi-objective optimization, it described the framework of d-Pareto and the conclusion that a d-Pareto dominance prediction could obtain a lower average prediction error rate comparing with Pareto demonstrated dominance prediction. Besides, it also explored the interaction between d-Pareto dominance prediction and multi-objective evolutionary algorithms. Experiments on several classic MOPs were conducted and the simulation results show that prediction of d-Pareto dominance is feasible and effective. [ABSTRACT FROM AUTHOR]

For quantitative-based and relationship-based embedding methods can not resist brightness enhancement and common attacks respectively, this paper proposed a hybrid quantization and relationship color image watermarking algorithm. Firstly, it subdivided each component of the color image to non-overlapping blocks of size 8x8 and performed 1-level discrete wavelet transform (DWT) for each selected block by using a key, and then did singular value decomposition (SVD) on the low and high frequency sub-band, respectively. Finally, the biggest singular value of low and high frequency sub-band exploited quantification and relationship method to embed preprocessed watermarking, respectively. Experimental results show that the proposed algorithm has low complexity and good transparency. Compared with other algorithms, it has better robustness performance. [ABSTRACT FROM AUTHOR]

Abstract:In the fields of scientific computing, big data processing, and artificial intelligence, it is very important to study the relevant application load, analyze the load I/O pattern to reveal the application load change law, etc., which is very important to guide the performance optimization of the cluster storage system. At present, there are many kinds of applications and the applications are updated rapidly and iteratively. The complex environment makes the feature mining of application load full of challenges. To address the above problems, we collected the application log information of five Lustre cluster storages in the production environment for 326 days, explored and analyzed the access and load charateristics of the application load, and verified and supplemented the existing observations. Through horizontal, vertical, and multi-dimensional comparative analysis and information mining of the application log information, we summarize four findings, explore the relationship between the relevant findings and previous research work, and then combine the actual production environment with the corresponding system optimization strategies. Feasible implementation schemes are given, which provide relevant references and suggestions for users, maintainers, upper application developers, multi-tier storage system designers, and other personnel. At the same time, because of the complex practical application environment and time-consuming work of system optimization, a system automation optimization framework (SAOF) is designed and implemented. SAOF can provide functions such as resource reservation and bandwidth limitation for specified application loads. Preliminary tests show that SAOF can provide automatic QoS guarantees for different tasks according to system resources and task load requirements. [ABSTRACT FROM AUTHOR]

Thrust vectoring can provide fighter with advantages regarding performance, survivability and detectability. Two types of fluidic control Convergent-Divergent nozzle thrust vector technology, which are Shock Vectoring controlling and Throat Shift, are numerically simulated and their performances are analyzed. A nozzle with fixed geometry from nozzle inlet to throat, and fixed length of divergent flap is researched. The relative position of the secondary injecting flow is fixed, and the injecting direction is always vertical to the nozzle main flow. The nozzle flow fields are obtained via CFD numerical simulation. It can be seen from the results that, Throat Shift method is suitable for the nozzle expansion ratio less than 1.5, and Shock Vectoring controlling method is contrary to Throat Shift method, which is suitable for the nozzle expansion ratio greater than 1.5. The Throat Shift method can restrict the nozzle mass flow besides thrust vectoring. The main influence of the secondary mass flow is the ratio of secondary total pressure to main flow total pressure. [ABSTRACT FROM AUTHOR]

Evacuation in an emergency is a complex behavior. When evacuation individuals are intelligent agents, an intelligent decision-making model is necessary to describe such a behavior. This paper elaborates how a modular model based on cellular automation is constructed with the advantages of information expression of cellular automation and behavioral expression of robots. The description of evacuation is realized through the assembly of such modules as evacuation time model, direction selection model and passage attraction model. When the model is used for describing the evacuation process of a hypermarket, the analog simulation and the data analysis show that it is effective in the descriptions of individual and group evacuations. [ABSTRACT FROM AUTHOR]

By using low temperature gasification, many kinds of biomass materials can be transformed into a gaseous mixture. This gaseous mixture includes combustible and incombustible gases. If the concentration of an individual component could be controlled, there is a possibility of using the gaseous mixture to fuel the internal combustion engine and finally to generate electricity. Furthermore, the utilizing of biomass fuel as an energy resource of internal combustion engine leads to a decrease in the emission of CO2, NOX, SOX, and particulate matters into the atmosphere. The components of biogas vary with the reactants and the reaction conditions. However, they usually include hydrogen (H2), carbon monoxide (CO), CH4, carbon dioxide (CO2), nitrogen (N2), and some other hydrocarbons. Under many conditions, the main components of biogas are CH4 and H2, as well as incombustible component CO2. Some researchers have carried out experimental researches to introduce the design and construction of internally circulating fluidized-bed gasifier (ICFG), to investigate the feasibility of gasifying manure compost using ICFG, and to evaluate the effects of pressure balance, reaction temperature, and steam ratio on the performance of the gasifier. The temperature conditions of the experiments were between 600°C and 700°C The results showed that the concentration of the components varied much with the reaction conditions. Different fuel components led to a different influence on combustion. Hydrogen has a much faster combustion velocity than CH4. As a result, combustion happens quickly with the increase in hydrogen composition in the fuel mixture. Meanwhile, carbon dioxide is an inert gas. It could cause an extinguishing of the flame if the composition of CO2 is too high. However, it is very difficult to avoid carbon dioxide in biogas. Moreover, the presence of CO2 leads to less input energy in fuel mixtures. Therefore, the combustion temperature will decrease. As a result, NOx emission will decrease. Since the influences of hydrogen and carbon dioxide on combustion are different, and the presence of CO2 also has benefits on engine performance, it is necessary to find out the balance point between combustion and exhaust emissions of the internal combustion engine which is fueled with the mixture of hydrogen, CH4 and carbon dioxide. And the main objective of the work in this paper is to research the influence of fuel components on engine operation stability. The experimental researches of engine operation stability were carried out based on a small-sized spark ignition engine fueled with simulated biogas, which includes hydrogen, CH4, and carbon dioxide. The influences of equivalence ratio, H2 concentration and CO2 concentration on combustion stability were investigated under wide opening throttle valve (WOT) and maximum brake torque (MBT) conditions. The results showed that engine operation stability was strongly influenced by fuel composition. Under low H2 concentration conditions, CO2 concentration played a dominant effect on combustion stability, and its increasing could induce the increase in cyclic variation and the occurrence of partial burn. However, under high H2 concentration, the effect of CO2 concentration on combustion gradually weakened. By adjusting fuel composition, the operation stability of biogas engines can be improved. [ABSTRACT FROM AUTHOR]

The experimental investigation of blockerless cascade thrust reverser based on secondary injection was conducted on the dual flow transonic and supersonic cascade test facility. Effect of parameters including fan outlet pressure ratios, secondary pressure ratios, secondary injection positions and secondray injection angles on the performance of blockerless cascade thrust resver were studied. The final results show that fan outlet pressure ratios and secondary pressure ratios has some complex relationship. When secondary pressure ratio less than a certain value, cascase reverse mass flow decreases with the increase of fan outlet pressure ratio, however if secondary pressure ratio esceed the value, it would present a opposite trend. In the whole experimental conditions, there exist a best secondary injection position (58.77 mm ≤ Xj ≤ 77.87mmgle (θ - 60°) achieving highest thrust reverse. [ABSTRACT FROM AUTHOR]

Jet attachment is a critical restriction for the usage of counter-flow thrust vectoring nozzle, which will lead to the control invalidation of vector thrust. Therefore more attention should be paid to jet attachment phenomenon and detachment control. Based on CFD technology, the jet attachment mechanism, characteristic and forming course were investigated, and two methods for jet detachment were proposed. One is to increase suction pressure, and the other is to enhance nozzle pressure ratio(NPR). The results show that jet detachment would be successfully achieved by implement of suction pressure and NPR control. However, hysteresis phenomenon existed in the suction pressure control course. The jet attachment suction pressure was 60.68kPa, while detachment pressure 65.86kPa. [ABSTRACT FROM AUTHOR]