多自由度振动系统响应集的支撑超平面法

对激励由凸集合建模的线性振动系统提出了响应集的概念，将数学上的微分包含问题简化为求解多自由度振动系统的响应集问题。在此基础上，利用凸集的性质提出了一种求解响应集的支撑超平面法，它是利用响应集的支撑超平面将问题转化为求解一类优化问题的解。对于三种典型的凸集载荷分别给出了各自的响应集，并比较和分析了它们的结果。

内近似约束空间整合的灵活性资源集群响应方法

针对规模化灵活性资源的管理需求,提出了一种内近似约束空间整合的灵活性资源集群响应方法。首先,建立储能、温控负荷和电动汽车充电桩的通用模型,并通过紧凑型约束空间描述其响应特性。其次,采用一种基于内近似与闵可夫斯基和的约束空间整合方法,实现对多个灵活性资源响应特性的整体描述。然后,采用一种灵活性资源集群的双层响应方法,既可利用整合后的等效模型形成集群的整体响应策略,又可根据个体特性和整体特性的映射关系,直接得到群内各个灵活性资源的响应策略。最后,通过仿真验证了所提方法的有效性。

基于参数序列化技术的电动汽车集群响应控制策略

为了对集群电动汽车充电负荷进行有效控制,提出了一种基于参数序列化技术,即能量状态优先队列(ESPL)的电动汽车集群响应控制策略。首先,类比热力学可控负荷诸如热泵的温度优先队列方法,确定电动汽车充电模型;继而定义了可与热泵的温度类比的电动汽车能量状态值,并将可与热泵开关状态类比的电动汽车充电状态作为控制对象,提出了用于对电动汽车群体进行控制的ESPL方法,与电动汽车预测模型相互配合,对电动汽车群体进行了有效控制。算例通过构造电动汽车目标功率,验证了此集群响应控制策略的有效性。

基于暖通负荷集群响应能力的电力系统频率控制策略

为提升系统频率稳定水平,提出了一种基于暖通空调负荷集群响应能力的电力系统频率控制策略,采用建筑采暖热泵作为可控负荷参与系统调频服务。首先,通过构建等值热力学参数模型来描述热泵的控制温度动态过程。进而根据用户温度舒适范围确定单体热泵的调频可控域,判断热泵是否可参与调频响应,保障热泵工作过程中的控制温度满足用户需求。同时,构建暖通空调负荷集群的频率调节架构,对集群频率调节能力进行量化。通过引入热泵温度状态SOT(state of temperature)参数与响应时间裕度作为频率控制参数,确定热泵的状态切换顺序,提出一种基于暖通空调负荷状态切换顺序的系统频率控制策略。通过仿真验证了所提出频率控制策略的有效性。

初级视皮层神经元集群对拓扑特征响应的可视化表征

神经元集群响应的高维特性是脑机制研究面临的主要困难之一.拓扑特征是图像的基本特征之一,为了有效表征高维的神经元集群响应的拓扑特征特性,提出了一种基于三维自组织映射网络采用RGB颜色特征表征神经元集群响应的动态可视化方法,分析多通道微电极阵列采集的大鼠初级视觉皮层(V1区)神经元集群信号,进而研究了V1区神经元集群对图形拓扑特征的响应特性.通过与主成分分析(PCA)方法进行对比发现:该方法能够有效表征V1区神经元集群对拓扑结构的时序动态响应特征,表征方式形象直观,具有一定的优越性.

基于集群响应的规模化电动汽车充电优化调度

大规模电动汽车(EV)的充电需求和充电负荷分布将呈现出规律性,从群体的角度对EV进行优化调度,可以降低问题的维度,提高优化计算的效率。基于区域EV的集群响应特性,建立了以负荷峰谷差最小化为目标的EV群体充电概率分布模型。在此基础上,根据EV群体对充电电价的灵敏度,建立EV集群响应的实时电价模型,通过电价对EV的充电行为进行有序引导,从而实现电网的"移峰填谷"策略。以典型的区域配电网负荷数据为例,验证了文中EV充电优化调度方法的有效性。最后,对EV群体响应实时电价的灵敏度,以及不同灵敏度下EV群体和代理商的节省成本进行讨论。

基于异常行为特征的僵尸网络检测方法研究

基于僵尸网络通信及网络流量的异常行为,可以有效检测出僵尸频道。介绍了通过对主机响应信息的异常分析,进而判断出当前IRC频道是否为一个僵尸频道的检测算法。由此引入了基于异常行为的僵尸频道检测模型,该模型分类提取IRC频道的主机响应信息,结合检测算法分析得出结论。实验结果验证了该模型的有效性。

面向电力系统扰动过程的动态特征研究

对电力系统实际运行过程中时常会发生的单一故障和由单一故障导致的连锁故障等演化过程中的动态特征进行研究,提取出能够反映电网动态特性的特征量,并采用蒙特卡罗方法对电网故障模式搜索方法进行了研究,建立了用于故障特征分析的样本集。同时采用相对变化率方法,在原始特征集中选取能够表征系统动态特性的特征量构建了动态响应特征集。研究结果为后继的大电网故障动态演化机理的研究奠定了基础。

鸽子视顶盖颜色信息的解码

研究了鸽子视顶盖神经元对颜色信息的编码机制并解码了三种颜色刺激。首先,针对鸽子视网膜四种类型敏感细胞设计了红、绿、蓝三种色块刺激模式。然后,对视觉实验采集到的神经元响应信号绘制其刺激后时间直方图(peri-stimulus time histogram,PSTH)。确定出神经元有效响应区间后发现,视顶盖神经元以集群的方式对颜色信息进行编码,对于不同的顶盖神经元,三种色块刺激的PSTH曲线存在不同的响应规律;对于同一个顶盖神经元,多次实验下三种色块刺激的PSTH曲线有着近乎一致的规律。最后,分别采用主成分分析法(primary component analysis,PCA)和等度规映射法(isometric mapping,ISOMAP)对集群特征进行降维,采用概率型神经网络(probabilistic neural network,PNN)对三种色块进行解码,结果表明,不同的特征降维方法,都具有较高的识别率,再次验证了鸽子视顶盖神经元是以集群的方式对颜色信息进行编码。

Mechanical properties of epoxy asphalt mixture pavement with lightweight aggregate applied on bascule bridge

The high temperature anti-rutting performance,water stability and low temperature bending property of epoxy asphalt mixture with 0%,15%,25%,40%,and 70% granulated and circular lightweight aggregates by weight are tested,respectively.The dynamic responses under the vehicle load and in the opening process are analyzed to obtain the mechanical responses of pavements by using the finite element method.The complicated structure including a steel deck and a waterproof adhesive layer is made to verify the bond strength of the 2451-type epoxy asphalt binder.Research results show that the epoxy asphalt mixtures with lightweight aggregate replacement percentages from 0% to 70% all satisfy the requirements for steel bridge pavements.The epoxy asphalt mixture with a 70% circular lightweight aggregate replacement percentage is recommended because of its smaller density when compared with other epoxy asphalt mixtures.The shear stress increases with the increase in the opening angle and achieves its maximum at the maximum opening angle of 85°.Test results show that the Tianjin Bascule Bridge can be used for first opening after a 3 d pavement conditioning.

Research on velocity and acceleration geophones and their acquired information

Based on the research of two geophone types （10 Hz moving-coil velocity and piezoelectric acceleration） and their velocity and acceleration parameters, frequency response functions have been determined, as well as the differences between them. Also, shock- vibration tests have been accomplished, not only to explain the two shock response signal differences, but also to analyze the response signal characteristics and its ability to carry information. In addition, seismic data acquisition experiments have been carried out under comparable conditions in the field. A contrast analysis of shot gathers and stack profiles acquired with the two geophone types is given in this paper. The results show that the acceleration signal from the acceleration geophone has a better advantage in terms of high signal-to-noise ratio, high accuracy, high resolution, and quantity of information to better meet current and future requirements for seismic exploration.

Click-Formed Polymer Gels with Aggregation-Induced Emission and Dual Stimuli-Responsive Behaviors

Stimuli-responsive polymer gels have recently attracted great attention due to their heat/solvent resistance,dimensional stability,and unique sensitivity to external stimuli.In this work,we synthesized thiol-functionalized tetraphenylethylene(TPE)and constructed polymer gels through thiol-ene click reaction.The synthetic process of the polymer gels could be monitored by fluorescence emission of TPE moieties based on aggregation-induced emission mechanism.In addition,due to the dual redox-and acid responsiveness of the polymer gels,in the presence of dithiothreitol and trifluoroacetic acid,fluorescence quenching of the polymer gels can be observed.This stimuli-responsive characteristics endows the polymer gels with potential applications in fluorescent sensing and imaging,cancer diagnosis and selfhealing materials.

Broadband seismic illumination and resolution analyses based on staining algorithm

Seismic migration moves reflections to their true subsurface positions and yields seismic images of subsurface areas. However, due to limited acquisition aperture, complex overburden structure and target dipping angle, the migration often generates a distorted image of the actual subsurface structure. Seismic illumination and resolution analyses provide a quantitative description of how the above-mentioned factors distort the image. The point spread function （PSF） gives the resolution of the depth image and carries full information about the factors affecting the quality of the image. The staining algorithm establishes a correspondence between a certain structure and its relevant wavefield and reflected data. In this paper, we use the staining algorithm to calculate the PSFs, then use these PSFs for extracting the acquisition dip response and correcting the original depth image by deconvolution. We present relevant results of the SEG salt model. The staining algorithm provides an efficient tool for calculating the PSF and for conducting broadband seismic illumination and resolution analyses.

Agent-Based Simulation for Interconnection-Scale Renewable Integration and Demand Response Studies

This paper collects and synthesizes the technical requirements, implementation, and validation methods for quasi-steady agent-based simulations of interconnectionscale models with particular attention to the integration of renewable generation and controllable loads. Approaches for modeling aggregated controllable loads are presented and placed in the same control and economic modeling framework as generation resources for interconnection planning studies. Model performance is examined with system parameters that are typical for an interconnection approximately the size of the Western Electricity Coordinating Council(WECC) and a control area about 1/100 the size of the system. These results are used to demonstrate and validate the methods presented.

An adaptive range-query optimization technique with distributed replicas

Replication is an approach often used to speed up the execution of queries submitted to a large dataset.A compile-time/run-time approach is presented for minimizing the response time of 2-dimensional range when a distributed replica of a dataset exists.The aim is to partition the query payload(and its range) into subsets and distribute those to the replica nodes in a way that minimizes a client's response time.However,since query size and distribution characteristics of data(data dense/sparse regions) in varying ranges are not known a priori,performing efficient load balancing and parallel processing over the unpredictable workload is difficult.A technique based on the creation and manipulation of dynamic spatial indexes for query payload estimation in distributed queries was proposed.The effectiveness of this technique was demonstrated on queries for analysis of archived earthquake-generated seismic data records.

Crack detection using integrated signals from dynamic responses of girder bridges

An innovative approach for the identification of cracks from the dynamic responses of girder bridges was proposed.One of the key steps of the approach was to transform the dynamical responses into the equivalent static quantities by integrating the excitation and response signals over time.A sliding-window least-squares curve fitting technique was then utilized to fit a cubic curve for a short segment of the girder.The moment coefficient of the cubic curve can be used to detect the locations of multiple cracks along a girder bridge.To validate the proposed method,prismatic girder bridges with multiple cracks of various depths were analyzed.Sensitivity analysis was conducted on various effects of crack depth,moving window width,noise level,bridge discretization,and load condition.Numerical results demonstrate that the proposed method can accurately detect cracks in a simply-supported or continuous girder bridges,the five-point equally weighted algorithm is recommended for practical applications,the spacing of two discernable cracks is equal to the window length,and the identified results are insensitive to noise due to integration of the initial data.

Engineering Design Optimization Based on Intelligent Response Surface Methodology

An intelligent response surface methodology (IRSM) was proposed to achieve the most competitive metal forming products, in which artificial intelligence technologies are introduced into the optimization process. It is used as simple and inexpensive replacement for computationally expensive simulation model. In IRSM, the optimal design space can be reduced greatly without any prior information about function distribution. Also, by identifying the approximation error region, new design points can be supplemented correspondingly to improve the response surface model effectively. The procedure is iterated until the accuracy reaches the desired threshold value. Thus, the global optimization can be performed based on this substitute model. Finally, we present an optimization design example about roll forming of a "U" channel product.

Effects of Heat Softening on Initiation of Landslides

Effects of heat softening on the initiation of slide surface(shear banding) in clayey slopes during fast deformation were discussed.Controlling equations considering heat,pore pressure and mechanical movement were presented.By perturbation method,the instability condition of localized zone(i.e.criterion for initiation of shear banding) for thermal related soils,such as clayey slope,was obtained.It is shown that slide surface initiates once the thermal-softening effects overcome the strain-hardening effects whether it is adiabatic or not.Without strain hardening effects,strain rate hardening obviously plays a role in initiation of shear band.During initiating process,heat is trapped inside the shear band,which leads rapidly to a pore pressure increase and fast loss of strength.The localized shear strain is concentrated in a narrow zone with a width of several centimeters at most and increases fast.This zone forms the sliding surface.Temperature can increase more than 2?C,pore pressure can increase 160% in about 0.1s inside this zone.These changes cause the fast decrease in friction-coefficient by about 36% over the initial value.That is how shear band initiated and developed in clayey slopes.

Characterization of Welding Induced Anisotropy in Steel by Magnetic Barkhausen Noise

Residual stress continues to be important issues in shipbuilding. This paper demonstrates how the heat affected zone that results from welding could be identified nondestructively using MBN （magnetic Barkhausen noise） technique. A stress concentration region was created by placing a weld bead on a marine steel plate used in ship construction. MBN measurements were made on the back surface of the welded plate along the weld direction and perpendicular to it in a line that crosses the weld bead. The stress distribution as deduced from the MBN measurements was found to be anisotropic in the material of the heat affected zone. The heat induced anisotropy was completely eliminated by shot peening the HAZ material as revealed by MBN intensity. It was concluded that the directional MBN measurements could be used to characterize the induced anisotropy and hence assess the thermal residual stresses distribution near a localized stresses concentration regions imposed by welding.

Ensemble Simulations of a Nonlinear Barotropic Model for the North Atlantic Oscillation

A numerical ensemble-mean approach was employed to solve a nonlinear barotropic model with chastic basic flows to analyze the nonlinear effects in the formation of the North Atlantic Oscillation （NAO）. The nonlinear response to external forcing was more similar to the NAO mode than the linear response was, indicating the importance of nonlinearity. With increasing external forcing and enhanced low-frequency anomalies, the effect of nonlinearity increased. Therefore, for strong NAO events, nonlinearity should be considered.