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通过单孔爆破振动监测实验,获取点振源的经验格林函数,利用单孔振源的格林函数来叠加合成群孔爆破振动时程。根据经验格林函数法原理建立了相应的爆破振动预测方法,编制了专用的预测分析软件。通过实例验证,若应用电子雷管精确控制起爆时差,预测目标点的群孔爆破振动波形与实测结果相当吻合。该方法获得的爆破振动预测准确度显著高于传统的回归统计分析法,不仅可以预报爆破振动峰值速度,也可对频率及持续振动时间进行预测.充分体现了爆破地震波的时频域信息,爆破振动的预测结果更全面。 相似文献
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为了分析及预测广西某航运过坝工程高边坡爆破振动的传播与衰减规律,进而减弱爆破振动效应,保护既有建(构)筑物,通过无量纲分析,推导出了反映高程效应的爆破振动传播规律预测模型。采用爆破测振仪在爆区附近设置5个监测点,对爆破所产生的振动进行监测、记录。根据实测数据,进行了非线性回归分析,对比了2种不同预测模型的预测精度。研究结果表明:高程对爆破振动效应具有较大的影响,传统预测经验公式的预测精度为83.48%,采用改进后的反映高程效应的模型的预测精确度较高,达97.03%,在复杂环境下,采用综合减振技术具有较好的降振效果。 相似文献
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往复式压缩机出口管线振动的分析与改造 总被引:1,自引:0,他引:1
某厂220×104t/a加氢处理装置在实际生产中发现加氢精制装置高分压力控制不稳,引起往复式压缩机出口管线振动。本文首先对往复式压缩机出口管线振动的原因进行分析,得出压力脉动为主要因素。然后,通过对管系的重要区段进行改造,将往复式压缩机采用的Ⅰ回Ⅰ,Ⅱ回Ⅱ的控制方案改为Ⅱ回Ⅰ的控制方案。并对改造前后的方案分别采用DDC控制系统进行动态模拟实验,得到高分压力随时间变化的关系图,并进行压力不均匀度计算。最后,对比二种方案高分压力随时间变化的关系图以及压力不均匀度,得出Ⅱ回Ⅰ的控制方案比Ⅰ回Ⅰ,Ⅱ回Ⅱ控制方案大大降低管线振动,使压力控制平稳。 相似文献
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振动试验夹具的优化设计及模态试验 总被引:2,自引:0,他引:2
将优化设计引入到夹具的设计环节中,运用拓扑优化和尺寸优化来合理布置材料分布以及优化板件厚度尺寸,提高夹具设计效率和设计质量,采用数字信号处理的方法对加工出来的夹具进行模态试验,将模态试验的结果与有限元模态分析的结果进行对比。证明了优化设计在夹具设计中的可靠性和适用性,为今后夹具的动态设计提供有价值的参考。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献