Time-domain dynamic constitutive model suitable for mucky soil site seismic response

Soil nonlinear behavior displays noticeable effects on the site seismic response.This study proposes a new functional expression of the skeleton curve to replace the hyperbolic skeleton curve.By integrating shear modulus and combining the dynamic skeleton curve and the damping degradation coefficient,the constitutive equation of the logarithmic dynamic skeleton can be obtained,which considers the damping effect in a soil dynamics problem.Based on the finite difference method and the multi-transmitting boundary condition,a 1D site seismic response analysis program called Soilresp1D has been developed herein and used to analyze the time-domain seismic response in three types of sites.At the same time,this study also provides numerical simulation results based on the hyperbolic constitutive model and the equivalent linear method.The results verify the rationality of the new soil dynamic constitutive model.It can analyze the mucky soil site nonlinear seismic response,reflecting the deformation characteristics and damping effect of the silty soil.The hysteresis loop area is more extensive,and the residual strain is evident.

Fast measurement and prediction method for electromagnetic susceptibility of receiver

Aiming at evaluating and predicting rapidly and accurately a high sensitivity receiver’s adaptability in complex electromagnetic environments,a novel testing and prediction method based on dual-channel multi-frequency is proposed to improve the traditional two-tone test.Firstly,two signal generators are used to generate signals at the radio frequency(RF)by frequency scanning,and then a rapid measurement at the intermediate frequency(IF)output port is carried out to obtain a huge amount of sample data for the subsequent analysis.Secondly,the IF output response data are modeled and analyzed to construct the linear and nonlinear response constraint equations in the frequency domain and prediction models in the power domain,which provide the theoretical criteria for interpreting and predicting electromagnetic susceptibility(EMS)of the receiver.An experiment performed on a radar receiver confirms the reliability of the method proposed in this paper.It shows that the interference of each harmonic frequency and each order to the receiver can be identified and predicted with the sensitivity model.Based on this,fast and comprehensive evaluation and prediction of the receiver’s EMS in complex environment can be efficiently realized.

Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.

三参数Normal-Ogive模型参数估计的SAEM算法

Normal-Ogive模型是项目反应理论的代表性模型之一,其参数估计主要是基于MCMC抽样实现的,但MCMC抽样的不足是计算效率较低。针对这一问题,本文以混合模型(mixture model)的视角,通过变量扩充,提出三参数normalogive(3PNO)模型题目参数估计的随机逼近EM(stochastic approximation EM,简称SAEM)算法,并通过Monte Carlo模拟对SAEM算法的主要影响因素、计算效率、估计的返真性进行验证。模拟研究的结果表明:SAEM算法能够准确实现3PNO模型题目参数估计的计算,并且具有较高的计算效率,表现出优良的计算性质。

Finite Mixture Normal Models, with Application to Dose-Response Studies

In this paper, we consider the risk assessment problem under multi-levels and multiple mixture subpopulations. Our result is the generalization of the results of [1-5].1 Finite Mixture Normal ModelsIn dose-response studies, a class of phenomena that frequently occur are that experimental subjects (e.g., mice) may have different responses like ’none, mild, severe’ after a toxicant experiment, or ’getting worse, no change, getting better’ after a medical treatment, etc. These phenomena have attracted the attention of many researchers in recent years. Finite

A HIGH ACCURATE TIME-DOMAIN-ADVANCE INTEGRATION METHOD FOR TRANSIENT ELASTODYNAMIC PROBLEMS

All step-by-step integration methods available at present for structural dynamic analysis use the displacement, velocity, and acceleration vectors computed at a previous interval for evaluating those at an advanced time step. Hence, an accumulated error will be definitely introduced after such integration. This paper presents a novel time-domain-advance integration method for transient elastodynamic problems in which the exact initial conditions are strictly satisfied for the solutions for each time step. In this way, the accumu- lated error can be eliminated and the approximate solutions will converge to the exact ones uniformly on the whole time domain. Therefore. the new method is more accurate. When applying to a structural dynamic problem, the present mehtod does not have to use the initial acceleration as is required by most other algorithms and the corresponding computation can be avoided. The present method is simple in representation, easy to be programmed, and especially suitable for accurate analyses of long-time problems. The comparison of numerical results with exact ones shows that the present method is much more accurate than some most widely used algorithms.

Artificial Neural Network-Based Development of an Efficient Energy Management Strategy for Office Building

In the current context,a smart grid has replaced the conventional grid through intelligent energy management,integration of renewable energy sources(RES)and two-way communication infrastructures from power gen-eration to distribution.Energy management from the distribution side is a critical problem for balancing load demand.A unique energy manage-ment strategy(EMS)is being developed for office building equipment.That includes renewable energy integration,automation,and control based on the Artificial Neural Network(ANN)system using Matlab Simulink.This strategy reduces electric power consumption and balances the load demand of the traditional grid.This strategy is developed by taking inputs from an office building electricity consumption behavior study,a power generation study of a solar photovoltaic system,and the supply pattern of a grid in peak and non-peak hours.All this is done in consideration of the Indian scenario,where real-time data of month-wise ANN-based intelligent switching has been established for intermittent renewable sources and peak load reduction,as well as average load reduction,has been demonstrated along with the power control loop without the battery system.

Analysis on advanced transient EM detectability of coal mine roadway

The hidden water-bearing structures near the roadway tunnelling face are very likely to cause water seepage accidents in coal mines.Currently,transient electromagnetic(EM)technology has be-come an important method to detect water damage in advance of roadway excavation.In this paper,the time-domain finite element algorithm based on unstructured tetrahedron grids is used to accurate-ly simulate the geological body in front of the roadway excavation face and analyze its response.The authors detect the distance between the roadway excavation face and the low-resistivity water-bearing body,the resistivity difference between the low-resistivity body and surrounding rock,and the influence of the size of the low-resistivity body on the transient EM response.Furthermore,the common types of low-resistivity bodies in the roadway drivage process are used for modeling to analyze the attenuation of the detected EM response when there are low-resistivity bodies in front of the roadway.The research in this paper can help effectively detecting the water-bearing low-resistivity body in front of the roadway drivage and lay a foundation for reducing the risk of water seepage accidents.

Comparison of the time-domain electromagnetic field from an infinitesimal point charge and dipole source

An electromagnetic field is generated through the accelerating movement of two equal but opposite charges of a single dipole. An electromagnetic field can also be generated by a time-varying infinitesimal point charge. In this study, a comparison between the electromagnetic fields of an infinitesimal point charge and a dipole has been presented. First, the time-domain potential function of a point source in a 3D conductive medium is derived. Then the electric and magnetic fields in a 3D homogeneous lossless space are derived via the relation between the potential and field. The field differences between the infinitesimal point charge and the dipole in the step-off time, far-source, and near-source zones are analyzed, and the accuracy of the solutions from these sources is investigated. It is also shown that the field of the infinitesimal point charge in the near-source zone is different from that of the dipole, whereas the far-source zone fields of these two sources are identical. The comparison of real and simulated data shows that the infinitesimal point charge represents the real source better than the divole source.

IRT框架下的SQRT/EM参数估计方法及应用研究

在项目反应理论(ItemResponseTheory,IRT)框架下,根据统计检验方法,提出了一种新的参数估计方法———SQRT/EM方法.现以双参数Logistic模型为例进行了蒙特卡洛模拟研究,结果显示:SQRT/EM方法有以下3个优点:①参数估计结果与同类流行软件Bilog相比,修复能力相当或略高;特别是样本容量大时表现更好;②能处理含有特殊反应模式的情况;③项目数、人数很少时参数估计的结果较稳定.

2PL模型的EM缺失数据处理方法研究

项目反应理论(IRT)模型是教育统计与测量中一种十分重要的模型,它包含项目参数和能力参数.目前一种常用的估计IRT模型项目参数的方法是由Woodruff和Hanson(1997)应用EM算法给出的,它用于完全反应数据,而把能力参数看作缺失数据.本文将Woodruff的方法推广到处理缺失反应的情况,基本思想是把能力参数和缺失反应均看作缺失数据,再运用EM算法估计参数.通过模拟研究,在不同被试人数和不同缺失比例的情况下,本文比较了我们给出的方法和BILOG-MG软件的缺失数据处理方法的参数估计效果.结果表明,在大多数情况下,本文提出的方法能得到更好的估计.

脱落酸与Em基因的表达调控

Em基因的表达受ABA诱导 ,干旱和盐胁通过增加ABA含量或改变植物细胞对ABA的敏感性而诱导Em基因的表达。植物Em基因启动子存在 3个功能区 :5′远端AT富集区通过影响转录调节表达量 ,作用类似于非专一性增强子 ;ABA应答元件ABRE在ABA存在的情况下与转录因子EmBP 1相互作用能显著增强Em基因的表达 ;

恩格列净通过上调Epac1表达抑制炎症反应减轻2型糖尿病大鼠肾损伤

目的 观察恩格列净(EM)对2型糖尿病(T2DM)大鼠肾损伤的治疗效果,并探讨其可能存在的机制。方法 将SD雄性大鼠随机分为正常对照(NC)组、 T2DM组和EM组,每组6只。T2DM组和EM组,给予腹腔注射链脲佐菌素(STZ)建立T2DM模型,记录各组大鼠空腹血糖(FBG)和体质量。EM组给予EM溶液灌胃,其余两组予以等量的羧甲基纤维素钠溶液灌胃,给药12周。记录大鼠体质量和FBG后处死大鼠,留存腹主动脉血液和肾脏组织。全自动生化分析仪检测血清肌酐(Scr)、血尿素氮(BUN)、尿酸(UA)、甘油三酯(TG)、总胆固醇(TC);行Masson染色、过碘酸希夫(PAS)染色、 HE染色观察肾脏组织学变化,透射电镜观察肾脏超微结构变化;免疫组织化学染色法检测大鼠肾脏组织中环磷酸腺苷直接激活的交换蛋白1(Epac1)、肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)、白细胞介素18(IL-18)的表达和分布。结果 与NC组相比,T2DM组大鼠体质量下降,FBG、 Scr、 BUN、 UA、 TC、 TG水平明显升高;肾小球基底膜增厚,足细胞足突融合,排列紊乱,内皮细胞窗孔消失;Epac1蛋白表达水平下降,TNF-α、 IL-1β、 IL-18的蛋白表达水平明显增高。与T2DM组相比,EM组大鼠体质量上升,FBG、 Scr、 BUN、 UA、 TC、 TG水平降低;肾损伤减轻,Epac1蛋白表达水平升高,TNF-α、 IL-1β、 IL-18的表达显著降低。结论 EM能够改善T2DM肾损伤。这种治疗效果是通过上调Epac1蛋白表达,抑制炎症反应介导的。

基于模糊Petri网和马尔科夫链理论的水电厂设备故障应急响应模型

为保证水电厂设备安全,避免因故障导致意外事故,基于模糊Petri网和马尔科夫链理论设计水电厂设备故障应急响应模型。确定加权因子命题阈值,结合传感器收集的初始信号,在滤波器的作用下还原信号特征,基于模糊Petri网提取水电厂设备故障特征。设计故障分类器,建立概率转移矩阵,设置概率转移矩阵的条件,面对动态解码,给定模型参数,计算马尔可夫模型下的连续变量密度函数,修正比例因子的状态系数,得到设备故障分类结果。建立设备故障应急响应模型,输出设备故障状态下的应急响应结果。实验结果显示,该模型在四种故障类型中的分类精度分别为98.8%、98.6%、98.7%、98.8%,可见该模型分类精度较好。

TIME-DOMAIN RESPONSES OF IMMERSING TUNNEL ELEMENT UNDER WAVE ACTIONS

The time domain responses of the tunnel element under wave actions during its immersion are investigated based on the linear wave diffraction theory. The integral equation is derived by using the time-domain Green function that satisfies the free water surface condition in the finite water depth, and is solved by the boundary element method. The motion equations of the tunnel element are solved by the fourth order Runge-Kutta method. A comparison between the computed and measured results reveals that the numerical model can effectively simulate the motion responses of the tunnel element and the cable tensions when the motions of the tunnel element are within some limit. Taking the tunnel element of 100 m in length, 15 m in width and 10 m in height as an example, the computational results of the motion responses of the tunnel element and the cable tensions in different immersing depths are obtained under different incident wave conditions.

横风荷载下电磁悬浮EMS型磁浮车辆动态响应特性分析

强烈的横风荷载会影响磁浮列车横向稳定性和安全。为全面了解横风荷载下电磁悬浮(EMS)型磁浮车辆的动态响应特性,建立了一个精细化的3D磁浮车辆多体动力学模型,并利用CFD(计算流体运动学)方法获得了磁浮车辆的气动载荷系数。基于"中国帽子风"阵风风速曲线计算生成横风荷载,进而通过时域动力学仿真,最终获得磁浮车辆车体与悬浮架的动态响应,并从车体位移、电磁悬浮系统和关键部件等方面细致全面地分析了横风荷载下EMS型磁浮车辆动态响应特性。

Fransdimensional Bayesian inversion of timedomain airborne EM data

To reduce the dependence of EM inversion on the choice of initial model and to obtain the global minimum, we apply transdimensional Bayesian inversion to time-domain airborne electromagnetic data. The transdimensional Bayesian inversion uses the Monte Carlo method to search the model space and yields models that simultaneously satisfy the acceptance probability and data fitting requirements. Finally, we obtain the probability distribution and uncertainty of the model parameters as well as the maximum probability. Because it is difficult to know the height of the transmitting source during flight, we consider a fixed and a variable flight height. Furthermore, we introduce weights into the prior probability density function of the resistivity and adjust the constraint strength in the inversion model by changing the weighing coefficients. This effectively solves the problem of unsatisfactory inversion results in the middle high-resistivity layer. We validate the proposed method by inverting synthetic data with 3% Gaussian noise and field survey data.

Detecting damage to offshore platform structures using the time-domain data

A new method that uses time-domain response data under random loading is proposed for detecting damage to the structural elements of offshore platforms. In our study, a time series model with a fitting order was first constructed using the time-domain of noise data. A sensitivity matrix consisting of the first differential of the autoregressive coefficients of the time series models with respect to the stiffness of structural elements was then obtained based on time-domain response data. Locations and severity of damage may then be estimated by solving the damage vector whose components express the degrees of damage to the structural elements. A unique aspect of this detection method is that it requires acceleration history data from only one or a few sensors. This makes it feasible for a limited array of sensors to obtain sufficient data. The efficiency and reliability of the proposed method was demonstrated by applying it to a simplified offshore platform with damage to one element. Numerical simulations show that the use of a few sensors’ acceleration history data, when compared with recorded levels of noise, is capable of detecting damage efficiently. An increase in the number of sensors helps improve the diagnosis success rate.

Unsplit-field higher-order nearly PML for arbitrary media in EM simulation

An unsplit-field higher order nearly perfectly matched layer(NPML)based on the auxiliary differential equation approach is introduced in three-dimensional finite-difference timedomain lattices.The proposed scheme has the advantage of both the NPML scheme and the higher order concept in terms of the improved absorbing performance and considerable computational efficiency.By incorporating with the generalized material independent concept,the proposed implementation is indepen dent of the material’s type.Thus,it has the advantages of terminating arbitrary media without changing the updated equations in the PML regions.Its effectiveness and efficiency is further demonstrated through numerical examples.

Nonlinear Time-Domain Theory for the Simulation of Moored Floating Body Motion

Nonlinear wave loads can induce low-frequency and high-frequency resonance motions of a moored platform in deep water. For the analysis of the nonlinear response of an offshore platform under the action of irregular waves, the most widely used method in practice is the Cummins method, in which the second-order exciting forces in the time domain are computed by a two-term Volterra series model based on incident waves, first-order body motion response, and quadratic transfer functions(QTFs). QTFs are bichromatic waves acting on a body and are computed in the frequency domain in advance. For moving bodies, QTFs are related to the first-order body response, which is to be determined in the simulation process of body motion response but is unknown in the computation procedure of QTFs. In solving this problem, Teng and Cong(2017) proposed a method to divide the QTFs into different components,which are unrelated to the body response. With the application of the new QTF components, a modified Cummins method can be developed for the simulation of the nonlinear response of a moored floating platform. This paper presents a review of the theory.