Advanced Materials Research Vols. 295-297

Abstract: In this paper, we use Acoustical BEM to predict the muffling effect of an air filter improvement with Helmholtz resonator of a domestic commercial vehicle. The result shows that the method works at some frequency range, which means there is a peak value of transmission loss close to the wanted frequency. And the position of the Helmholtz resonator is optimized.

Abstract: From an analysis of random process with modal analysis method, formulas of related parameters for an analysis of structural dynamic reliability have been deduced first in the paper, accordingly, prepares “the PMDK dynamic reliability analysis program” by Fortran programming language. Next, Some parameters for vehicular load probability distribution model have been derived by a method of unconstrained planning, Combining with an observation data for vehicle distribution at a long-span old bridge, the author has obtained the model in this paper. Finally, author has calculated a dynamic reliability for the long-span old bridge under a specific vehiclar load by the program and studied a relationship between dynamic reliability and displacement as well as sectional position and influences of damping and elastic modulus on its dynamic rerliability. Meanwhile the author also has studied a relationship between dynamic reliability and time and influences of structural unilateral and bilateral reliability.At last all aboved conclusions have been confirmed by Monte Carlo method.

Abstract: The mechanical performance and durability of hardened granular- cement paste material such as mortar and concrete are affected by its earlier stage behavior which is defined in terms of consistency and/or workability. Therefore understanding the behavior of the mixture during this early period is a crucial requirement for the technical and economical success of professional production sites. This paper presents a numerical approach based on Discrete Element Method (DEM) to simulate the macroscopic behavior of a fresh granular-cement paste mixture in which the pasty behavior is dominant. The research approach is based on a conceptual idea where the particle-paste interaction system is explicitly modelled by means of a two phase particle interaction system. The effect of the characteristics of paste on the macroscopic fresh behavior of a mixture has been studied and compared by the mini slump cone test regarding the excess paste theory. Modelling and experimental laboratory test results show good agreement.

Abstract: Fresh granular-pasty materials are considered as an intermediate class between solid and fluid. These materials are capable of showing their rheological behavior which can be close to either a pasty or granular system depending on properties and proportion of ingredients in the mixture. Therefore, quantification of such dependencies is a crucial factor in order to be able to predict the performance of this type of material. In this study a two phase model is considered in which a mixture is decomposed into a paste and a granular phase. The relation between the aggregate grading and the consistency of the mixture has been investigated for a concrete in which the pasty behavior is dominant. It was found that if the volume and property of the paste that remains after filling the space in between the aggregates in compacted state is kept constant, the consistency of a mixture can be characterized by the number of aggregates corresponding to each grain size regarding the sieve analysis test. The paper presents a modelling approach and experimental results.

Abstract: Aiming at the installation location measuring requirement of cone rod located at some kind of laser target for inertial confinement fusion, a non-contact five-coordinate measuring machine is exploited and built. According to the projection characteristic of spatial line, the mathematical model of spatial angle between the cone rod and support rod is established. Based on this projection method, the direction vector of cone rod centerline can be obtained by testing the cone rod from two perpendicular directions with CCD camera. LOG operator is applied to detect the edge of image. The experiments illustrate the measuring accuracy of angle can reach 0.1 degree with the projection method.

Abstract: For any On-orbit Space camera, the influence of flutter on the imaging process of TDICCD space camera is inevitable, thus causing the decline of image quality. This paper briefly introduces the principle of TIDCCD camera and how flutter affects the imaging process. Then through the analysis and calculation of practical program, we find the acceleration criterion to avoid the blur of image quality.

Abstract: Based on the dynamic model of the nonlinear vibration system which driven by double exciting motors, the rotate speed difference and phase difference state space equations have been deduced. According to the design feature of the nonlinear vibration system and the vibration synchronization requirement of double exciting motors, the approach control synchronization strategy has been deduced with sliding mode reaching law. The practical examples and tests shows that the reaching law synchronization controller can effectively control the double exciting motors to realize the synchronization movement, and the synchronization controller has stronger robustness. The analysis result can provide the theoretical and test basis for the further exploitation of synchronization vibrating machine.

Abstract: From the theory of structure-bone sound radiation, the properties of vibration and noise of scroll compressor are analyzed, and the relationship of them is researched. On the basis of the analysis, the feasibility for measuring noise level using vibration signal is demonstrated. Then, the noise radiant efficiency curve is plotted using the test data, and disadvantages of this mean are pointed out. At last, a new method of measuring noise level using vibration signal, which is proved in practice effectively, is presented based on neural network.

Abstract: The effect of flotation parameters such as flotation consistency, temperature, flotation time, air to pulp ratio, velocity of pulp flow (turbulence level), and pH on old newspaper/old magazine deinking efficiency was studied by using a laboratory deinking cell developed by ourselves. The optimized flotation conditions were: flotation consistency 1.2%, 50°C, 6min, air to pulp ratio 50%, velocity of pulp flow 3.5m/s and pH 8.5. By using the optimized flotation conditions, the deinked pulp brightness could reach 59.15%ISO, 10.18%ISO higher than that of the control, the effective residual ink concentration was 234.65 mg/kg, which less heavily than 875.56 mg/kg of the control, theoretical deinking efficiency was up to 84.42%.

Abstract: To study artificially produced and actively controlled water hammer wave caused by hydraulic vibration exciter, a mathematical model was established and an experimental system was designed to verify it. Through the given partial differential equations, a computer code based on the method of characteristics was developed to calculate transient pressure distributed along the pipe under different rotational frequency of vibration exciter. The numerical simulation indicates that there is a simple harmonic vibration rising at the cross sections along the pipe, corresponding to different excitation pressure at every cross section. In addition, the excitation pressure can also be adjusted by system pressure via overflow valve. So, this work is expected to serve for the optimum design of the hydraulic excitation system and play a theoretical guiding role to experimental research in future.