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应力状态 3

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Determination of effective stress parameter of unsaturated soils: A Gaussian process regression approach

Pijush Samui, Jagan J

《结构与土木工程前沿（英文）》 2013年第7卷第2期页码 133-136 doi: 10.1007/s11709-013-0202-1

摘要： This article examines the capability of Gaussian process regression (GPR) for prediction of effective stress parameter ( ) of unsaturated soil. GPR method proceeds by parameterising a covariance function, and then infers the parameters given the data set. Input variables of GPR are net confining pressure ( ), saturated volumetric water content ( ), residual water content ( ), bubbling pressure ( ), suction ( ) and fitting parameter ( ). A comparative study has been carried out between the developed GPR and Artificial Neural Network (ANN) models. A sensitivity analysis has been done to determine the effect of each input parameter on . The developed GPR gives the variance of predicted . The results show that the developed GPR is reliable model for prediction of of unsaturated soil.

关键词： unsaturated soil effective stress parameter Gaussian process regression (GPR) artificial neural network (ANN) variance

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The formation mechanism and the influence factor of residual stress in machining

null

《机械工程前沿（英文）》 2014年第9卷第3期页码 265-269 doi: 10.1007/s11465-014-0311-0

摘要：

Residual stresses generated in cutting process have important influences on workpiece performance. The paper presents a method of theoretical analysis in order to explicate the formation mechanism of residual stresses in cutting. An important conclusion is drawn that the accumulated plastic strain is the main factor which determines the nature and the magnitude of surface residual stresses in the workpiece. On the basis of the analytical model for residual stress, a series of simulations for residual stress prediction during cutting AISI 1045 steel are implemented in order to obtain the influences of cutting speed, depth of cut and tool edge radius on surface residual stress in the workpiece. And these influences are explained from the perspective of formation mechanism of residual stress in cutting. The conclusions have good applicability and can be used to guide the parameters selection in actual production.

关键词： residual stress analytical model strain plastic cutting parameter

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Stress-strain relationship with soil structural parameter of collapse loess

SHAO Shengjun, YU Qinggao, LONG Jiyong

《结构与土木工程前沿（英文）》 2008年第2卷第3期页码 293-293 doi: 10.1007/s11709-008-0100-0

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Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

《结构与土木工程前沿（英文）》 2007年第1卷第3期页码 281-285 doi: 10.1007/s11709-007-0036-9

摘要： Structure modal parameter online identification was used to monitor the structural health as evidenced by changes in the vibration characteristics. The natural excitation technique and the eigensystem realization algorithm were combined to identify the modal parameters in the time domain of a structure excited by simulated ambient vibrations. The mass-normalized mode shapes were obtained from the eigen-sensitivity analysis. The experimental modal analysis was performed on a two-story steel braced frame model excited by simulated ambient vibrations and hammer impacts. The mass-normalized mode shapes were acquired by changing the structural mass and by eigen-sensitivity analy sis. From finite element analysis results and the experimental data, it is shown that this method is effective.

关键词： eigensystem realization eigen-sensitivity analysis realization algorithm vibration effective

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Damage-constitutive model for seawater coral concrete using different stirrup confinements subjected to axial loading

《结构与土木工程前沿（英文）》 2023年第17卷第3期页码 429-447 doi: 10.1007/s11709-022-0913-2

摘要： Recently, the application of detrital coral as an alternative to natural aggregates in marine structures has attracted increased attention. In this study, research on the compressive performance of coral aggregate concrete (CAC) confined using steel stirrups with anti-rust treatment was experimentally conducted. A total of 45 specimens were cast, including 9 specimens without stirrups and under different strength grades (C20, C30, and C40) and 36 specimens under different strength grades (C20, C30, and C40). Moreover, three stirrup levels (rectangular, diamond-shaped compound, and spiral stirrups) and different stirrup spacings (40, 50, 60, and 70 mm) were used. Subsequently, the stress−strain curves of specimens subjected to axial loading were measured. The effects of the stirrup spacing and stirrup configurations on the stress and strain were investigated, respectively, and the lateral effective stress of the different stirrups was calculated based on the cohesive-elastic ring model and modified elastic beam theory. Moreover, a damage-constitutive model of CAC considering the lateral stress was set up based on damage mechanics theory. The results indicated an increase in the stress and strain with a decrease in the stirrup spacing, and the adopted stirrup ratio had a better strengthening effect than the different concrete grades, and the variation in the deformation was restricted by the performance of coral coarse aggregate (CA). However, an increment in the lateral strain was observed with an increase in the axial strain. The lateral stress model showed a good agreement with the experimental data, and the proposed damage-constitutive model had a good correlation with the measured stress−strain curves.

关键词： coral aggregate concrete stress−strain curves lateral effective stress peak stress axial−lateral curves damage-constitutive model.

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大型镍矿深部高应力矿体充填法开采关键技术与对策

杨志强,高谦,陈得信,郭慧高

《中国工程科学》 2014年第16卷第8期页码 38-44

摘要：

金川镍矿是我国最大的硫化铜镍矿，以地应力高、矿体厚大和矿岩不稳固著称国内外采矿界。该矿体开采难度之大、充填成本之高备受国内外采矿界关注。近年来，随着矿床开采深度逐年增加已接近千米，采场面积超过1×10⁵ m²，高温、高压和高渗压的“三高”采矿环境日趋显著，不仅提高了采矿成本，而且还给矿山安全高效生产带来巨大压力。本文首先概述金川深部矿床采矿技术条件，然后明确采矿生产面临巷道和采场稳定性控制技术难题，分析采场围岩变形和岩层移动所潜在的灾变失稳风险。最后提出了金川深部矿体安全高效开采亟待攻克的技术难题，为金川深部资源开发能力和综合利用指明了方向。

关键词：金川镍矿深部开采高应力关键技术研究方向

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单缝桥梁在温度作用下的结构受力计算

赵怡彬,邵旭东

《中国工程科学》 2012年第14卷第10期页码 103-112

摘要：

桥台处伸缩缝问题是长期困扰工程界的难题，它会带来跳车、桥梁局部损坏、伸缩缝装置经常更换等各种问题。为有效解决这一问题，提出了一种适用于大中型桥梁的新型结构体系——单伸缩缝桥梁（单缝桥）。在考虑接线路面裂缝开展的情况下，建立了温度作用下单缝桥的简化计算模型，推导了单缝桥受力、变形的理论公式，用Fortran90编制程序，进行计算。以一座总长280 m的单缝梁桥为例，温度降低20 ℃时，接线路面钢筋最大应力为148 MPa，最大裂缝宽度为0.185 mm，符合规范要求；台后结构对主梁产生的附加应力仅为0.105 MPa，影响很小。通过对影响单缝桥性能的因素：支座类型、配筋率、接线路面长度、摩擦系数、土体刚度、桥长、温差等进行分析，绘制图表，得到以下主要结论：温降时，接线路面受拉，混凝土开裂，是较不利的状况；30 m长的接线路面可以满足结构受力和变形的需要；选择摩擦系数较小的支座和减少接线路面与垫层的摩擦力可以减少结构内力，在接线路面与垫层间推荐加铺土工格栅。

关键词：单缝桥梁温度作用受力与变形理论公式参数分析

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Processing parameter optimization of fiber laser beam welding using an ensemble of metamodels and MOABC

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0703-5

摘要： In fiber laser beam welding (LBW), the selection of optimal processing parameters is challenging and plays a key role in improving the bead geometry and welding quality. This study proposes a multi-objective optimization framework by combining an ensemble of metamodels (EMs) with the multi-objective artificial bee colony algorithm (MOABC) to identify the optimal welding parameters. An inverse proportional weighting method that considers the leave-one-out prediction error is presented to construct EM, which incorporates the competitive strengths of three metamodels. EM constructs the correlation between processing parameters (laser power, welding speed, and distance defocus) and bead geometries (bead width, depth of penetration, neck width, and neck depth) with average errors of 10.95%, 7.04%, 7.63%, and 8.62%, respectively. On the basis of EM, MOABC is employed to approximate the Pareto front, and verification experiments show that the relative errors are less than 14.67%. Furthermore, the main effect and the interaction effect of processing parameters on bead geometries are studied. Results demonstrate that the proposed EM-MOABC is effective in guiding actual fiber LBW applications.

关键词： laser beam welding parameter optimization metamodel multi-objective

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Estimation of the minimum effective dose of tramadol for postoperative analgesia in infants using the

null

《医学前沿（英文）》 2012年第6卷第3期页码 288-295 doi: 10.1007/s11684-012-0208-4

摘要：

Tramadol is a potent analgesic. However, the analgesia efficacy of tramadol, particularly its minimum effective dose (MED), is not clear. The aim of this study is to find MED of tramadol for postoperative analgesia in infants. The continual reassessment method (CRM) was performed to find MED. Infants undergoing surgeries were included in the 3 phases of this series. In each phase, 24 participants were allocated a different tramadol dose. Pain intensity was measured by face, legs, activity, cry, consolability (FLACC) measurement at 3-hour intervals. Tramadol was considered ineffective if the FLACC score was higher than 4 in 10 at anytime. In phase 1, seven dose levels were used within the range 0.1–0.4 mg?kg^-1·h^-1. Phase 1 was insufficient to identify the MED, and we increased the dose to 0.4–0.8 mg?kg^-1·h^-1 in phase 2. Phase 2 was insufficient to identify the MED. In phase 3, local anesthetic wound infiltration was introduced, and the tramadol dose levels tested were the same as in phase 1. The successful analgesia probability of tramadol 0.4 mg?kg^-1?h^-1 was 82.1% (95% CI, 0.742–0.925) in phase 1. In phase 2, it was 84.7% (95% CI, 0.789–0.991) with the dose 0.8 mg?kg^-1?h^-1. Phase 1 and phase 2 were insufficient to identify the MED. In phase 3, the successful analgesia probability for dose 0.35 mg?kg^-1?h^-1was 96.7% (95% CI, 0.853–0.997).We have demonstrated that tramadol provides insufficient analgesia for surgeries considered to cause moderate-to-severe postoperative pain in infants if used as the sole analgesic, and that local anesthetic wound infiltration enhances the efficacy of tramadol.

关键词： tramadol minimum effective dose postoperative analgesia infants continual reassessment method

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Developing effective tumor vaccines: basis, challenges and perspectives

XU Qingwen, CHEN Weifeng

《医学前沿（英文）》 2007年第1卷第1期页码 11-19 doi: 10.1007/s11684-007-0003-9

摘要： A remarkable advance in tumor immunology during the last decade is the elucidation of the antigenic basis of tumor recognition and destruction. A variety of tumor antigens have been identified using several strategies including conventional experiments and newly developed bioinformatics. Among these antigens, cancer/testis antigen (CT antigen) is considered to be the most promising target for immunotherapy by vaccination. Successful immunotherapy of tumors requires understanding of the natural relationship between the immune system and tumor in the status of differentiation, invasion and maturation. Continued progress in development of effective cancer vaccines depends on the identification of appropriate target antigens, the establishment of optimal immunization strategies without harmful autoimmune responses and the ability of manipulating tumor microenvironment to circumvent immune suppression and to augment the anti-tumor immune response.

关键词： development conventional identification elucidation Successful immunotherapy

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新安江模型参数有效优化及不确定性评估

王文川,程春田,邱林,杨斌斌

《中国工程科学》 2010年第12卷第3期页码 100-107

摘要：

应用新安江模型进行水文模拟时，由于模型本身的不足及参数多、信息量少等原因，会出现率定的最优参数组不唯一、不稳定等问题。考虑到以往的参数优选，都只得出一个参数组，不能反映出其不确定性状况。提出应用基于马尔可夫链蒙特卡罗（MCMC）理论的SCEM-UA算法，通过双牌流域以1 h为时段间隔的36场典型洪水数据对新安江模型参数进行优选和不确定性评估。结果表明，该算法能很好地推出新安江模型参数的后验概率分布；率定和检验结果分析也表明，应用SCEM-UA算法对新安江模型进行优选和不确定评估是有效和可行的。

关键词：新安江模型参数率定不确定性评估 SCEM-UA

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非饱和土的塑性体应变与剪应变的相互作用原理

王靖涛

《中国工程科学》 2007年第9卷第11期页码 11-15

摘要：

将岩土塑性体应变与剪应变的相互作用原理拓展到了非饱和土领域。除了塑性体应变与剪应变的相互作用外，在非饱和土中出现了两类新的相互作用，吸力-塑性体应变和孔隙气压力-塑性体应变。吸力具有二重性质，其对塑性体应变作用包括两个相反的方面。基于吸力性质，阐明了非饱和土的一些独特的性质，诸如有效应力参数的物理涵义，吸力对体积变化和前期固结压力的影响和湿陷机理等。另外，应用拓展的塑性体应变与剪应变相互作用原理，从理论上证明了非饱和土的临界状态线是存在的和唯一的，以及它与应力历史无关。

关键词：塑性体应变与剪应变的相互作用原理非饱和土基质吸力有效应力原理

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1000 MW ultra-supercritical turbine steam parameter optimization

FENG Weizhong

《能源前沿（英文）》 2008年第2卷第2期页码 187-193 doi: 10.1007/s11708-008-0030-5

摘要： The 2 × 1000 MW ultra-supercritical steam turbine of Shanghai Waigaoqiao Phase III project, which uses grid frequency regulation and overload control through an overload valve, is manufactured by Shanghai Turbine Company using Siemens technology. Through optimization, the steam pressure is regarded as the criterion between constant pressure and sliding pressure operation. At high circulating water temperature, the turbine overload valve is kept closed when the unit load is lower than 1000 MW while at other circulating water temperatures the turbine can run in sliding pressure operation when the unit load is higher than 1000 MW and the pressure is lower than 27 MPa This increases the unit operation efficiency. The 3D bending technology in the critical piping helps to reduce the project investment and minimize the reheat system pressure drop which improves the unit operation efficiency and safety. By choosing lower circulating water design temperature and by setting the individual Boiler Feedwater Turbine condenser to reduce the exhaust steam flow and the heat load to the main condenser, the unit average back pressure and the terminal temperature difference are minimized. Therefore, the unit heat efficiency is increased.

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Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

《机械工程前沿（英文）》 2020年第15卷第1期页码 55-65 doi: 10.1007/s11465-019-0545-y

摘要： When a fast-steering mirror (FSM) system is designed, satisfying the performance requirements before fabrication and assembly is vital. This study proposes a structural parameter design approach for an FSM system based on the quantitative analysis of the required closed-loop bandwidth. First, the open-loop transfer function of the FSM system is derived. In accordance with the transfer function, the notch filter and proportional-integral (PI) feedback controller are designed as a closed-loop controller. The gains of the PI controller are determined by maximizing the closed-loop bandwidth while ensuring the robustness of the system. Then, the two unknown variables of rotational radius and stiffness in the open-loop transfer function are optimized, considering the bandwidth as a constraint condition. Finally, the structural parameters of the stage are determined on the basis of the optimized results of rotational radius and stiffness. Simulations are conducted to verify the theoretical analysis. A prototype of the FSM system is fabricated, and corresponding experimental tests are conducted. Experimental results indicate that the bandwidth of the proposed FSM system is 117.6 Hz, which satisfies the minimum bandwidth requirement of 100 Hz.

关键词： fast-steering mirror structural parameter PI controller bandwidth notch filter

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Energy efficient cutting parameter optimization

Xingzheng CHEN, Congbo LI, Ying TANG, Li LI, Hongcheng LI

《机械工程前沿（英文）》 2021年第16卷第2期页码 221-248 doi: 10.1007/s11465-020-0627-x

摘要： Mechanical manufacturing industry consumes substantial energy with low energy efficiency. Increasing pressures from energy price and environmental directive force mechanical manufacturing industries to implement energy efficient technologies for reducing energy consumption and improving energy efficiency of their machining processes. In a practical machining process, cutting parameters are vital variables set by manufacturers in accordance with machining requirements of workpiece and machining condition. Proper selection of cutting parameters with energy consideration can effectively reduce energy consumption and improve energy efficiency of the machining process. Over the past 10 years, many researchers have been engaged in energy efficient cutting parameter optimization, and a large amount of literature have been published. This paper conducts a comprehensive literature review of current studies on energy efficient cutting parameter optimization to fully understand the recent advances in this research area. The energy consumption characteristics of machining process are analyzed by decomposing total energy consumption into electrical energy consumption of machine tool and embodied energy of cutting tool and cutting fluid. Current studies on energy efficient cutting parameter optimization by using experimental design method and energy models are reviewed in a comprehensive manner. Combined with the current status, future research directions of energy efficient cutting parameter optimization are presented.

关键词： energy efficiency cutting parameter optimization machining process