Applied Mechanics and Materials Vols. 157-158

Abstract: Following the adequate model of the reciprocating compressor piping system and the compressor design parameters, operating conditions and gas parameters, the mechanical system of compressor piping, gas-column system, pressure pulsations and of vibration response are numerically simulated. And the main factor bringing to the compressor piping system vibration is identified. A reasonable way to controlling piping vibration is developed to achieve a better efficiency. Keywords: Compressor; Pipe vibration; Vibration Analysis; numerical simulation.

Abstract: In order to investigate the effect of the suture density on the mechanical properties of bioprosthetic heart valve, we establish the spherical leaflets models via computer aided design. Finite element analysis is used simulate the mechanical performance of bioprosthetic heart valve when leaflet is closed. The analysis results show that suture density has a significant effect to the stress state of valve, which may lead not only to different stress peak values, but also to different stress distributions. High or low density suture isn’t appropriate for long-term durability of the bioprosthetic heart valve. Suture density tests are needed to perform on the valves to find satisfactory suture density for better mechanical properties of the bioprosthetic heart valve.

Abstract: The Design of intelligence pipeline leakage detector is nondestructive inspection using leakage detection principle to the internal metal defects, corrosion of pipeline.The detector adopts discrete sampling, realizing 12-bits high-speed multichannel-data collection through the FPGA, amount of the data can be up to 1024 road; and store mass data through ARM at the same time, shared data will be uploaded to the computer of control center through the network, the intelligent data analysis system engineering real-time analysis and quantitative identification, judge pipeline safety operation, provides the basis for safe duty time and maintenance cycle.

Abstract: By constructing a multistage floating-bed system by combination of macrophytes, aquatic animals and aquamats ecobase for ecolgical restoration in a eutrophic urban river, the improvement of water quality and the dynamic variation of phytoplankton was investigated. The results showed that the average removal rates were 9.85%, 15.86%, 24.47% and 12.75%, respectively. phytoplankton quantity was decreased by 22.82×104ind./L and Shannon-Weiner Index was increased by 0.11 averagely, after the restoration work in the demonstration area comparing to control area. The negative correlation between Shannon-Weiner Index of phytoplankton and TN(-0.77, P<0.01) showed that multistage system might effect phytoplankton indirectly through removing nutrients from river, which indicated that the employment of ecological restoration technology of multistage floating-bed system was effective in raising the ecological recovery efficiency of polluted water bodies.

Abstract: In this paper, we designed the variable FU array consisting of single FU for transform in H.264. The paper highlights the design of FU array which can accommodate the operation block of various sizes. We implemented the FU array processor, and some experiments are conducted so as to verify the architecture. The proposed variable FU array can be extended to FU array that will give a scalability feature to coding tools of MPEG-1/2/7/21 and H26x.

Abstract: The paper adopts multi-boy dynamics software and simulates and analyzes the banana type vibrating screen. The paper obtains the result of vibration amplitude of vibrating screen at its working through computing；we can get the resonance by analyzing the amplitude curve , which is a significant guidance for design, improvement and maintenance.

Abstract: The abrasive wear and the wear resistance of composite nickel + SiC coatings are investigated. The coatings are deposited by the method for electroless nickel plating EFTTOM-NICKEL developed in TU-Sofia. Nanosized particles of SiC are used as a strengthened material. The size of the particles is 35-40 [nm]. The thickness of the coatings is 50 [µm]. The investigation of the coatings deposited on the different roughness surfaces is performed. Some of the samples are thermal processed at 300°C, 6 hours after deposition process. The methods for wear resistance testing is developed and the experimental results for the dependence of the massive wear, wear speed, intensity of wear and wear resistance on the friction road and the time of a contact interaction are obtained.

Abstract: The sliding frictional contact problem for a laterally graded half-plane has been considered. Two finite element (FE) models, in macro and micro scales have been developed to investigate the effective parameters in contact mechanics of laterally graded materials loaded by flat and triangular rigid stamps. In macro scale model, the laterally graded half-plane is discretized by piecewise homogeneous layers for which the material properties are specified at the centroids by Mori-Tanaka method. In micro scale model, functionally graded material (FGM) structure has been modeled as ideal solid quadrant particles which are spatially distributed in a homogeneous matrix. Boundary conditions and loading is the same in both models. The microstructure has modeled as rearrangement and sizes changing of particles are possible to provide the possibility of crack nucleation investigation in non-singular regions. Analyses and comparison of the results showed that micro and macro scale results are in very good agreement. Also, increasing the grains aspect ratio and using optimum distribution of grains decrease stress distribution roughness on the surface. Therefore, the possibility of surface cracking far from stamp’s edges decreased.

Abstract: An aero dynamical finite element model on rotary hammering test stand was established in this paper. The external flow field of the model was analyzed by CFD module of ANASYS-FLOTRAN. The distribution of flow velocity and that of flow pressure were obtained, which were analyzed to provide theoretical references for optimum design of impact plate.

Abstract: The prestressing wires of prestressed concrete cylinder pipe (PCCP) provide core concrete with compressive stress to resist internal pressure. Broken wires resulting from corrosion and embrittlement may cause cracking in pipe wall and increase the risk of failure with time. In order to reveal the mechanism of longitudinal cracking in PCCP with broken wires, a simplified model is developed and the maximum number of broken wires to preclude onset of longitudinal cracking can be determined conveniently by the equations derived in this paper. Verification against results of finite element analysis shows that the presented method has decent accuracy for appropriate effective pipe length and wall thickness. By comparing the calculated maximum number of broken wires with the actual number of broken wires detected by inspection and monitoring technologies, longitudinal cracking in prestress loss zone can be predicted, thus aiding condition assessment of PCCP.