Advanced Materials Research Vols. 268-270

Abstract: In the Context of integration of the Tri-networks, digital libraries start running its individual knowledege service to express its using value. Basic on the gereral introduction of integration of the Tri-networks, this paper will discuess the stratiges of running the individual knowledge services.

Abstract: The serial communication between microcomputer and other devices is often used in industrial controls, this paper mainly introduces the realization of RS485 serial communication between a single microcomputer and multiple siemens MicroMaster inverters based on Delphi, and as an example this paper explain the generality of the serial communication between microcomputer and others serial devices.

Abstract: The theory and practice of Institutional Repository in developed countries of Europe and America have clearly demonstrated that the construction of Open Access Institutional Repository aspects has the vital significance in promoting scientific research and improving academic institutions visibility. From Institutional Repository functions, in this article, the author analyzes localization retrieval and browse of a DSpace-based Institutional Repository system to provide reference for our country on the construction and development of the Institutional Repository.

Abstract: Centrifugal pump performance has transient effect obviously during rapid changing period and the pump hydrodynamic performance of transient is different from steady-state process. In order to research the speed regulation characteristics and the inner flow mechanism of the centrifugal pump, numerical method of solving the unsteady fluid flow around the accelerating blade was established. The dynamical changes of the pressure and velocity were simulated by Fluent6.2, using standard k-epsilon turbulence model, PISO algorithm. The dynamic mesh technology and UDF were used to deal with the moving boundary caused by changing speed. Simulation results shown that faster angular acceleration made larger pressure fluctuations. Different regulated time had different influence in the system transient characteristics. And the evolution of the internal flow rate present strong transient performance in the regulating process. The study confirmed the feasibility of dynamic mesh method in solving the transient fluid flow during pump regulating period.

Abstract: In order to study the uncertain nonlinear jamming problem in UCAV’s flight control system, a method using jamming observer to check the system’s jamming was designed. Based on jamming observer, a flight control law was constructed, which reduced the restrictive condition for the jamming. The simulation results show that the adaptive flight control law based on jamming observer, make UCAV’s flight control system have good stability and robustness, it’s a great convenience analyzing the system stability.

Abstract: With the development of Web service theories and technologies, it has been an effective approach to satisfy users’ requirements by service composition. For independent global constraints Web services composition problem, the paper presents an optimization method of Web service composition with constraint using fuzzy Petri net(FPN), which can transforms solving the optimal service composition problem into locating the largest trust value of legal firing sequences in the FPN model. Then we use the cooperative algorithm including simulated annealing and genetic algorithm (SAGA) to find the optimal legal sequences. The experimental results show that the method can not only reduce the time cost, but also find more feasible solutions.

Abstract: At present, developers can rapidly generate applications through Web service composition, the quality of service (QoS) of web service composition is important, but most of the existing composition methods are difficult to balance the QoS indexes (Such as time and price). In this paper, a web service composition method based on the price-time Petri net is proposed, the minimum cost can be obtained by modeling based on price time Petri net, and presents a method of priced state class to analyze the cost of web service composition model. Theoretical analysis and case analysis show that the price-time Petri net method is feasible to study Web service composition with the minimum cost.

Abstract: This paper presented the key problems to shorten “semantic gap” between low-level visual features and high-level semantic features to implement high-level semantic image retrieval. First, introduced ontology based semantic image description and semantic extraction methods based on machine learning. Then, illustrated image grammar on the high-level semantic image understanding and retrieval, and-or graph and context based methods of semantic image. Finally, we discussed the development directions and research emphases in this field.

Abstract: With the widespread use of smart phones in current social, the SMS chat has become a new way of communication among people. However, a variety of advertising, recruitment and some unwelcome sexy messages are being sent to people’s phone. SMS Firewall is a kind of filter software that can obstruct SMS which you defined as harassment. The paper describes how to achieve this function on iPhone OS with some tools like class-dump, Xcode and MobileSubstrate.

Abstract: OFDM is a promising digital communications technique for high data rate transmissions. In this paper, we have analyzed the performance of mobile OFDM systems in the presence of channel estimation error. A new channel estimation error model is presented. Based on the estimation error model, new and simple expressions for the average bit error probability of M-QAM OFDM systems are derived for zero-forcing, minimum mean square error and maximum likelihood receivers. A complex correlation coefficient is used to quantify the quality of the channel estimation scheme. We have shown that if the complex correlation coefficient is a function of the signal to noise ratio, then the inter-carrier interference caused by channel variations is the dominant source of performance degradation. On the other hand, if the channel estimation scheme produces a constant value for the complex correlation coefficient (estimation quality is not a function of the signal to noise ratio), then the channel estimation error will cause an error floor that is larger than the one caused by the inter-carrier interference, and is considered as one of the dominant causes of degradation. And channel estimation using pilot symbols are discussed in terms of different pilot symbol placement schemes.