The vibration reduction effects of a new vibration module which was composed of double-layer tubular structures and the middle filling material were investigated with the methods of numerical ...simulation and experiment. The attenuation decibels of the vibration levels were measured and analyzed under various working conditions. It is testified that results of numerical simulation of the soil vibration which are in good agreement with the measured data are credible. It is indicated by the analysis results that the vibration isolation module has good effect on damping vibration in each frequency band. The results can provide references for the design of vibration isolation modules for pier foundation.
In order to improve the efficiency of the hedge trimmer, and meet the fast, efficient and safe performance of the hedge trimmer . In this paper, the design and theoretical research of its ...electro-hydraulic control system are carried out. On the basis of using SolidWorks to complete the three-dimensional model of the whole machine, the control system scheme is completed with the hydraulic system, and the main electronic control components are selected. Determine its pin assignment based on function and selected controller and complete the transfer of information between the control system modules via CAN bus communication technology. And through the labview to test its debugging process, and finally complete the actual verification of the machine, the results show that the CAN communication of the electronic control system is normal, all parts work well, can meet the pruning requirements, the electronic control system is effective and feasible.
Surface seawater and boundary layer air samples were collected on the icebreaker Xuelong (Snow Dragon) during the Fourth Chinese Arctic Research Expedition (CHINARE2010) cruise in the North Pacific ...and Arctic Oceans during 2010. Samples were analyzed for organochlorine pesticides (OCPs), including three isomers of hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and two isomers of heptachlor epoxide. The gaseous total HCH (HCHs) concentrations were approximately four times lower (average 12.0 pg m3) than those measured during CHINARE2008 (average 51.4 pg m3), but were comparable to those measured during CHINARE2003 (average 13.4 pg m3) in the same study area. These changes are consistent with the evident retreat of sea ice coverage from 2003 to 2008 and increase of sea ice coverage from 2008 to 2009 and 2010. Gaseous -HCH concentrations in the atmosphere were typically below the method detection limit, consistent with the expectation that ocean currents provide the main transport pathway for -HCH into the Arctic. The concentrations of all dissolved HCH isomers in seawater increase with increasing latitude, and levels of dissolved HCB also increase (from 5.7 to 7.1 pg L1) at high latitudes (above 73°N). These results illustrate the role of cold condensation processes in the transport of OCPs. The observed airsea gas exchange gradients in the Arctic Ocean mainly favored net deposition of OCPs, with the exception of those for -HCH, which favored volatilization.
In this paper, the loop-tree basis function combined with the precondition, namely, incomplete Cholesky (IC), is used to analyze the scattering problems from conducting objects.
Contact algorithm between different bodies plays an important role in solving collision problems. Usually it is not easy to be treated very well. Several ones for material point method were proposed ...by Bardenhangen, Brackbill, and Sulsky\cite{Bardenhagen2000,Bardenhagen2001}, Hu and Chen\cite{Hu_Chen2003}. An improved one for three-dimensional material point method is presented in this paper. The improved algorithm emphasizes the energy conservation of the system and faithfully recovers opposite acting forces between contacting bodies. Contrasted to the one by Bardenhagen, both the normal and tangential contacting forces are more appropriately applied to the contacting bodies via the contacting nodes of the background mesh; Contrasted to the one by Hu and Chen, not only the tangential velocities but also the normal ones are handled separately in respective individual mesh. This treatment ensures not only the contact/sliding/separation procedure but also the friction between contacting bodies are recovered. The presented contact algorithm is validated via numerical experiments including rolling simulation, impact of elastic spheres, impact of a Taylor bar and impact of plastic spheres. The numerical results show that the multi-mesh material point method with the improved contact algorithm is more suitable for solving collision problems.
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