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Fan W.,Beihang University | Xu Z.,Beijing University of Technology | Xu Z.,Beijing Municipal Institute of Labour Protection | Wang W.-X.,Hong Kong University of Science and Technology
Environmental Pollution | Year: 2014

Jinzhou Bay in Northern China has been seriously contaminated with metals due to the impacts of smelting activities. In this study, we investigated the relationship between metal accumulation in a deposit-feeding polychaete Neanthes japonica and metal concentration and geochemical fractionation (Cd, Cu, Pb, Zn and Ni) in sediments of Jinzhou Bay. Compared with the historical data, metals in the more mobile geochemical fraction (exchangeable and carbonate fractions) were gradually partitioned into the more stable fraction (Fe-Mn oxides) over time. Metal concentration and geochemical fractionation in sediment significantly affected metal bioavailability and accumulation in polychaetes, except for Ni. Metal accumulation in polychaetes was significantly influenced by Fe or Mn content, and to a lesser degree by organic matter. Prediction of metal bioaccumulation in polychaetes was greatly improved by normalizing metal concentrations to Mn content in sediment. The geochemical fractionation of metals in sediments including the exchangeable, organic matter and Fe-Mn oxides were important in controlling the sediment metal bioavailability to polychaetes. © 2014 Elsevier Ltd. All rights reserved. Source


Pang L.,Beijing Municipal Institute of Labour Protection | Pang L.,Beijing Institute of Technology | Zhang Q.,Beijing Institute of Technology | Wang T.,Beijing Municipal Institute of Labour Protection | And 2 more authors.
Safety Science | Year: 2012

A laneway support system provides an available way to solve problems related to ground movements in underground coal mines, but also poses another potential hazard. Once a methane/air explosion occurs in a laneway, inappropriate design parameters of the support system, especially the support spacing, likely have a negative influence on explosion disaster effects. The commercial software package AutoReaGas, a computational fluid dynamics code suitable for gas explosions, was used to carry out the numerical investigation for the methane/air explosion and blast process in a straight laneway with different support spacing. The validity of the numerical method was verified by the methane/air explosion experiment in a steel tube. Laneway supports can promote the development of turbulence and explosion, and also inhibit the propagation of flame and shock wave. For the design parameters in actual laneway projects, the fluid dynamic drag due to the laneway support plays a predominant role in a methane/air explosion. There is an uneven distribution of the peak overpressure on the same cross section in the laneway, and the largest overpressure is near the laneway walls. Different support spacing can cause obvious differences for the distributions of the shock wave overpressure and impulse. Under comparable conditions, the greater destructive effects of explosion shock wave are seen for the laneway support system with larger spacing. The results presented in this work provide a theoretical basis for the optimized design of the support system in coal laneways and the related safety assessments. © 2011 Elsevier Ltd. Source


Li X.,Beijing Municipal Institute of Labour Protection
Journal of Sound and Vibration | Year: 2013

A scaling approach is proposed for the vibration analysis of line-coupled plates at high frequencies. It extends earlier scaling approaches for an isolated system to coupled systems. Based on the power flow balance in the plate assembly, a general scaling law is derived and a scaled model is built accordingly. Due to the dynamic similitude in a statistical sense, the scaled model is able to simulate the dynamics of the original system at high frequencies. Numerical examples validate the efficiency of the approach and suggest the application of finite element methods in the high-frequency vibration analysis. © 2013 Elsevier B.V. All rights reserved. Source


Li X.,Beijing Municipal Institute of Labour Protection
Journal of the Acoustical Society of America | Year: 2010

This paper is concerned with the ensemble statistics of the dynamic responses of a random system subjected to harmonic excitations. Random point process theory is employed to derive general scaling laws with the Gaussian orthogonal ensemble assumption about the system natural frequencies. A scaled model is built to simulate the high-frequency vibrations of the original system. Specific forms of the scaling laws are presented for a mass-loaded plate regarding the scaling factors for the structural parameters. The ensemble statistics predicted from the scaled model are compared favorably with those obtained from the original system. © 2010 Acoustical Society of America. Source


Li X.,Beijing Municipal Institute of Labour Protection
Journal of the Acoustical Society of America | Year: 2010

This analysis presents a scaling approach to predict high-frequency mean responses of vibrating systems. The basis of the approach lies in the dynamic similitude between the original systems and the scaled models. A general scaling law is formulated using Skudrzyks mean-value theorem and its specific form is derived for the case of a flexural plate. Modal density is scaled down to reduce the computational cost in the high-frequency mean response prediction. Different scaling procedures are numerically experimented and some insights are given about the accuracy of the scaling approach as compared with a dense finite element analysis. © 2010 Acoustical Society of America. Source

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