Computer Simulation of Thermal-Mechanical Processing

AlterationIntroductionThereisastrongini6ractionamongtemPetalrefield,strCssfield,andmicrosttuctutulaltOrationinm8terialsduringtheirhotworking[l'2].Especiallyduringthecoolingprocess,inwhichtemPeratorechangnsgreatly,intendionsbecomemorecomplexbecauseoftransformationoccurmnce.Duringthehotdeformation,thingswillaPpearsuchas:a.hotdeformation,relatedtostressfieId,changesessentiallytheshaPeofmaterialsandcausesthevariationofthecontactstatebetWeenthedieandsample,resultinginchangeofthethermalboundnyco…     

跨世纪档案人才的培训与教育工作

阐述了跨世纪档案人才的培训目标、素质条件、选拔原则、培训内容及培训措施。     

国有小型运输企业股份合作制改造的思考

对国有小型运输企业实行股份合作制进行了探讨     

Dynamic response of offshore jacket structures under random loads

In this paper, the dynamic response of a scale model of a jacket offshore structure is investigated both theoretically and experimentally. The experiments were conducted both in air and in water. The in-water experiments were done in the towing tank of Memorial University to simulate the realistic operating conditions. The model was subjected to random wave loads. Froude's law of modeling was used to obtain the dimensions of the scale model based on the dimensions of an existing structure. The effects of varying the structure's weight, and the characteristics of the wave loading were investigated. The structure's weight was changed by adding weights to the structure's deck. A finite element model was designed to determine the dynamic response of the model. Excellent agreement between the experimental and theoretical results was obtained.The reaction force at the foundation was estimated from strain measurements and compared with the finite element calculations. Fair agreement was obtained.This work is the first stage of a project whose objective is to develop a method for structural damage detection using the free vibration response of the structure. The free vibration response will be obtained from the stationary random response of the structure using the random decrement method. Having an accurate model to describe the dynamic response of the structure is the first step in this study.     

Analysis on Ground Surface Deformation and Influence of Construction Parameters Caused by Two Different Shield Machines in Double-tube Tunnelling北大核心CSCD

Based on a shield-driven running tunnel project of Hangzhou Metro Line 2, this paper carries out field measuring of the ground surface deformation caused by two different shield machines in double-tube tunnelling in soft soil areas, obtains the laws of the surface deformation caused by shield-driven double-tube tunnelling and verifies the applicability of the modified Peck formula to double-tube tunnelling. The results show that in soft soil areas the impacts on ground surface deformation caused by different shield construction parameters in the previously and subsequently excavated tunnels are different, while the surface deformation changes sharply before and after the shield machine passing through the cutting face, and a rebound phenomenon occurs when the shield tail passes through the cutting face due to the influence of the grouting; The cutterhead torque of the shield machine in soft soil areas can be composed of five calculation factors, and the calculation results are in good agreement with the measured values. The larger the opening rate of the shield cutterhead is, the larger the average torque value will be, the higher the percentage of large ground loss rate will be, and the larger the maximum ground surface settlement will be; The ratio of cutterhead torque T to mucking volume per ring Q is used as the control parameter for analyzing the ground surface settlement, and a certain positive correlation between the ratio and the surface settlement value is determined, the smaller the cutterhead opening rate is, the more accurate the fitting results will be. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Chaotic movement of vortices in superconductors of high-Tc superconducting maglev system at a high speed

Vortex motion in superconductors of higb-Tc superconducting maglev system is studied by a computational simulation.The vortex system is treated in a similar fashion,as a system where defects arc arrang...     

灰铸铁飞轮疲劳失效分析

大马力飞轮是商用车一款大马力发动机的零部件,其搭载大马力发动机为商用车提供动力总成。飞轮在工作期间,因经常与离合器摩擦,售后市场出现离合器打滑,起步困难、抖动较大等整车问题,拆解后发现,飞轮表面出现磨损不平、表面微裂纹为主要的失效形态的现象。     

Multiaxial stress creep rupture mechanisms of AZ31 magnesium alloy

The maximum principal stresses, von Mises effective stresses and principal facet stresses at the time of creep rupture were compared in uniaxial, biaxial, and triaxial stress states for AZ31 magnesium alloy. The creep rupture of this alloy was experimentally controlled by cavitation, which was the result of a low damage tolerance, λ. Creep deformation could be correlated with the von Mises effective stress parameter. The failure-mechanism control parameter governing the stress state coincided with the experimental results of the rupture of the materials under multiaxial stress states. Finally, the theoretical prediction based on constrained cavity growth and continuous nucleation agreed with the experimental rupture data to within a factor of three.     

Correcting injection pressure maladjustments to reduce NOX emissions by marine diesel engines

Emissions from the exhausts of marine diesel engines comprises several different gases including NO_X. These are currently regulated at the international level under Regulation 13 of ANNEX VI of MARPOL 73/78, but this regulation only applies to new engines and is based on bench tests, for only a single engine designated the “parent engine”. Here, the need to take measurements from across their whole range and once in operation on board a vessel is examined. This would not only improve assessment of new equipment against the current regulation, but would also detect defects in the functioning of the engine.     

Implementation of discharging/charging current sensorless state-of-charge estimator reflecting cell-to-cell variations in lithium-ion series battery packs

This paper offers novel insights to the design and implementation of an innovative state-of-charge (SOC) estimator for the lithium-ion (Li-Ion) series battery pack. The most interesting feature of this approach is that it can utilize information from each filtered terminal voltage of the Li-Ion cells connected in series for SOC estimation of the battery pack. Without actual sensing each discharging/charging current (DCC) applied to the Li-Ion cells, it is possible to extract each DCC estimation from the corresponding filtered terminal voltages with an equivalent electrical circuit model (EECM) identification of all Li-Ion cells in the battery pack. There are two advantages to SOC estimation of the battery pack with this approach. First, the proposal can be implemented simply and effectively, reducing the computational steps required for SOC estimation. By reducing computational steps, the proposal is expected to be more cost-effective. Second, the approach guarantees an improved SOC performance, even if the battery pack results in inevitable cell-to-cell variation among Li-Ion cells. Accordingly, there are fewer differences to previously estimated DCCs among Li-Ion cells. Specifically, all values from the estimated DCCs are properly compensated for by simultaneous parameter modification according to each cell’s electrochemical characteristics. Experimental results clearly demonstrate that our DCC sensorless SOC estimator provides robust SOC performance for the battery pack. This approach considered an experimental battery pack (12S1P) connected in series using 2.6 Ah LiCoO2 cells produced by Samsung SDI.