沂沭断裂带构造地球化学观测结果分析

为了监测郯庐断裂带跨活动断裂地球化学组分变化特征,利用在沂沭断裂带上的安丘—莒县断裂勘选出的5条地球化学观测测线剖面观测资料,分析了不同测线的土壤气体浓度(Rn,CO2和H2)和测值分布特征。结果表明:断裂活动性质、活动强度、构造组合和裂隙分布对跨活动断层的地球化学测项测值分布具有控制作用,地球化学测项测值分布与活动断裂两侧地层结构、类型和密实程度密切相关,跨活动断层不同地球化学测项分布存在一定的相关性。

Two-stage numerical simulation for temperature profile in furnace of tangentially fired pulverized coal boiler

Considering the fact that the temperature distribution in furnace of a tangential fired pulverized coal boiler is difficult to be measured and monitored, two-stage numerical simulation method was put forward. First, multi-field coupling simulation in typical work conditions was carried out off-line with the software CFX-4.3, and then the expression of temperature profile varying with operating parameter was obtained. According to real-time operating parameters, the temperature at arbitrary point of the furnace can be calculated by using this expression. Thus the temperature profile can be shown on-line and monitoring for combustion state in the furnace is realized. The simul-(ation) model was checked by the parameters measured in an operating boiler, (DG130-9.8/540.) The maximum of relative error is less than 12% and the absolute error is less than 120℃, which shows that the proposed two-stage simulation method is reliable and able to satisfy the requirement of industrial application.

The Precursory Meanings of the Deviation of the Magnitude-Frequency Distribution of Earthquakes from the Gutenberg-Richter Law

The Gutenberg-Richter law (G-R law) of the magnitude-frequency distribution of earthquakes has been an important base in seismology for a long time. However, the actual magnitude-frequency distribution usually deviates from the G-R law. Based on the experimental results of three different rock samples, which contain macro-asperity, compressional en-echelon fault and model-Ⅲ shear fault, the correlative coefficient (r) was calculated by fitting the sequences of the acoustic emissions with the G-R law in every scanning time window. We investigated the changes of the correlative coefficient, which describes the actual deviation of magnitude-frequency distribution of earthquakes from the G-R law within the specific scanning time window. According to the results of the rock samples containing macro-asperity and compressional en-echelon fault respectively, the value decreases prior to the rock fracture, meaning that the deviation of magnitude-frequency distribution from the G-R law tends to be larger. The result of the model-Ⅲ shear fault didn’t show obvious decrease before the final rock fracture. Actually, the studies of some earthquakes also show deviation before the occurrence of moderate earthquakes. The results obtained in this paper will provide us with some useful clues for studying precursors before the occurrence of moderate earthquakes with the data of regional earthquake activities.

Stretch rate and deformation for pre-stretching aluminum alloy sheet

Numerical simulation combined with experimental test was carried out to analyze the pre-stretching process of the 7075 aluminum alloy sheet,from which the stress variation curves and residual stress of aluminum alloy sheet in different stretch rates were obtained.The results show that the residual stress in length direction is released after unloading the stretch force,while the residual stress in width direction is released during the stretching process.The study of residual stress elimination is beneficial for optimizing stretch rate on the basis of residual stress distribution law.By comparing the variation principle of residual stress in length direction,the size range of three deformation areas and elimination percentage of residual stress were obtained.The residual stresses of clamping area and transition area are not eliminated effectively,so sawing quantity should be the sum of both the areas.The elimination rate of residual stress in even deformation area could reach 90% after choosing a proper stretch rate,which is verified by both simulation and experiment.

Composite failure prediction of π-joint structures under bending

In this article, the composite π-joint is investigated under bending loads. The ＂L＂ preform is the critical component regard- ing composite π-joint failure. The study is presented in the failure detection of a carbon fiber composite π-joint structure under bending loads using fiber Bragg grating （FBG） sensor. Firstly, based on the general f＇mite element method （FEM） software, the 3-D finite element （FE） model of composite π-joint is established, and the failure process and every lamina failure load of composite π-joint are investigated by maximum stress criteria. Then, strain distributions along the length of FBG are extracted, and the reflection spectra of FBG are calculated according to the strain distribution. Finally, to verify the numerical results, a test scheme is performed and the experimental spectra of FBG are recorded. The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions, and the computational error of failure load is less than 6.4%. Furthermore, it also verifies the feasibility of the damage detection system.