Applied Mechanics and Materials Vols. 148-149

Abstract: Artificial neural networks can be used for building prognostic models of various engineering problems. This paper presents an example of how we can predict the time of fire resistance based on the given experimental and numerical results. The analyses concerning the behavior of the reinforced-concrete construction elements during the standard fire, together with the basic theoretical information and detailed problem description, as well as the graphical curves for the fire resistance of the reinforced-concrete pillars, are given in the doctoral theses of Prof. Cvetkovska [3]. Using the concepts of artificial neural networks and the results of the performed numerical analyses as input parameters we made the prediction model for determination of the time of fire resistance of reinforced-concrete pillars. The neural network generated excellent results which will be presented further below in this paper.

Abstract: To improve the cooling efficiency of turbine blade, a multidisciplinary design optimization (MDO) system involving aerodynamics, heat transfer and structures has been developed. In this system, a MDO procedure for a turbine blade with complicate internal structure is performed. The structural size of rib turbulators, partitions and trailing edge cooling slots, which serve as design variables, is used for parametric modeling of three dimensional turbine blade. Conjugate heat transfer analysis is employed to get the temperature of the blade. The temperature in the blade body obtained from former coupled analysis is specified as boundary conditions for structural analysis. Meanwhile, a combined algorithm of multi-island genetic algorithm (MIGA) and sequential quadratic programming (SQP) is applied for optimization in specified space. While the flow rate of cooling air remains unchanged, the maximum and average temperatures of the blade decrease under the condition of meeting the strength requirement. The result shows that the cooling efficiency of turbine blade is improved, and the system exhibits higher stability, feasibility and efficiency for engineering applications.

Abstract: An improved particle swarm optimization (PSO) algorithm is designed for the grid based wireless homo-sensor network position problem. The proposed method, called guided method, introduces the simulation of migration process to PSO and its mutation algorithm, using a previous designed sparse position plan to guide the swarm to the optimization solution, and accelerates the search process. Experiments show not only the feasibility and validity of the proposed method but also a marked improvement in performance over traditional PSO.

Abstract: In this paper, the phase transformation behaviors of shape memory alloy (SMA) in the complex stress state are formulated based the one-dimensional phase transformation model supposed by Zhou and Yoon. The stress field near the crack tip of mode II in SMA is described based on linear elastic fracture mechanics. The phase transformation behaviors of SMA near the crack tip of Mode II are numerically investigated.

Abstract: Large scale belt conveyor is a key device to transport bulk-solid material for long distance. It is necessary to build rational virtual prototype model, analysis dynamic performance of belt conveyor. Comparing with traditional physical prototyping and experimental way, shorter design cycle and lower development costs will be got by using virtual prototype. It is helpful to choose the best design which is rational in technique, safe and reliable in running, feasible in economy. Considered actual working conditions, a virtual prototype model is built and validated by dynamics analysis. Three starting methods including direct starting mode, traditional Harrison method and soft starting are compared. The simulation results of virtual prototype show that direct starting method will lead to higher dynamic tension extreme value and larger fluctuation, dynamic tension is significantly reduced with the traditional Harrison method, and the average dynamic tension of soft starting consider the actual condition is dropped to minimum and the whole system is more stable.

Abstract: With the aim of energy-saving and environment protection, Chinese government and energy consumers are focusing on energy recovery from municipal reclaimed water using the heat pump during building heating and cooling. Municipal reclaimed water assembled in treatment units need to be transmitted to satisfy remote heating and cooling demands in large-scale utilization projects, and transmission distance between treatment units and energy consumers is an important problem greatly affecting the efficient and economic performance of a municipal reclaimed water source heat pump system. Three key problems depending on transmission distance were analyzed. Reclaimed water temperature variation along the delivering pipeline was discussed in consideration of the mutual influence between the transmission medium and the circumjacent soil. Energy consumption of the transmission process was calculated based on pipeline frictional resistance, transmission energy consumption ratio was proposed as an evaluation index reflecting the system energy-saving rate; the transmission distance influence on economic performance was evaluated by dynamic investment payback period and internal return rate. A comprehensive model to determine the transmission distance was presented, which can provide a theoretical analysis tool for system design.

Abstract: The sintering behavior and microwave dielectric properties of the 16CaO-9Li2O-12Sm2O3-63TiO2 (abbreviated CLST) ceramics doped by small amount of LBS (Li2O-B2O3-SiO2) glass were investigated in this paper. The adding of LBS glass improved the densification of the CLST ceramics and the sintering temperature of the CLST ceramics had been efficiently lowered to 1000°C. Especially, the 10wt.% LBS doped CLST sintered at 1000°C for 3h has optimum microwave dielectric properties of Kr=69, Q×f=2846GHz, and TCF=9.7ppm/°C, indicating that it could be a suitable candidate for LTCC applications.

Abstract: This paper aimed at constructing a two-tier on-line testing system. Questions were designed based on integration of concept cartoons and multimedia in hopes that the unexplainable contents of an object can be appropriately represented and interpreted through the means of concept cartoons, and that student’s understanding of the questions and interests in test taking can be effectively enhanced through pictorial presentation of concept cartoons. This system was to construct a testing tool through which tests were conducted to explore third graders’ magnetism misconception. The outcomes indicated that incorporation of concept cartoons in multimedia on-line testing can improve accuracy than traditional written test on paper. During the study, 14 magnetism misconceptions entertained by the pupils were identified and classified. Further, the on-line testing tool can attain satisfactory results in system utilization, animation design, attracting students’ attention and enhancing their understanding of the questions. It demonstrated the fact that integration of concept cartoons with two-tier on-line testing can improve question comprehension and students’ attention.

Abstract: In this paper ,we discus a wide class of loss functions for non-negative matrix factorization (NMF) and derive flexible and improved NMF algorithms based alpha-divergences for error measures, which generalize or combine several different criteria in order to extract intrusion signal.

Abstract: ZnS:Fe and ZnS:Fe/ZnS core-shell nanocrystals were synthesized by chemical precipitation method. It was found that the ZnS: Fe based nanocrystals possess zinc blende structure. Compared to ZnS: Fe nanocrystals, the intensity of the X-ray diffraction peaks of ZnS: Fe/ZnS nanocrystals reduced and these peaks moved to lower angles. TEM images show that ZnS: Fe based nanocrystals are spheroidal and the average particles size is about 3~4 nm. PL spectra of ZnS: Fe nanocrystals revealed several mission bands, ~406nm, ~444nm, ~416nm, However, PL spectra of ZnS: Fe/ZnS nanocrystals showed several mission bands, ~420nm, ~432nm, ~449nm.