Fragility Curves of Existing RC Buildings Based on Specific Structural Performance Levels

In seismic risk mitigation policies, fragility functions of existing buildings play a fundamental role. In this paper, a procedure to develop analytical fragility curves for Moment Resisting Frame Reinforced Concrete buildings is presented. The design of the selected building typologies was performed according to the codes at the time of construction using force-based methods and the state of the practice at the time of construction. A total of 216 building classes were defined, considering different ages, number of storeys, infill panels, plan dimensions, beam stiffness, and concrete strength. The investigated buildings can be considered low-engineered buildings, using no seismic codes or old seismic codes. The seismic capacity of the selected models representing the existing RC buildings has been evaluated through non-linear dynamic simulations. Seismic response has been analyzed, considering various peak and integral intensity measures and various response parameters, such as ductility demands and Interstorey Drift Ratio (IDR). A new relationship among structural performance, damage levels and interstorey drift ratios for each studied type is introduced, which is calibrated using the damage levels described in EMS98. It is important to highlight that in this study, different thresholds of IDR have been associated with different typologies, considering their different ductility member levels after their different structural responses. Fragility Curves (FCs) for the studied structural types are set up, developed and discussed.

Multireference configuration interaction potential curve and analytical potential energy function of the ground and low-lying excited states of CdSe

The potential energy curves （PECs） of the ground state （^3∏） and three low-lying excited states （^1∑, ^3∑,^1∏） of CdSe dimer have been studied by employing quasirelativistic effective core potentials on the basis of the complete active space self-consistent field method followed by multireference configuration interaction calculation. The four PECs are fitted to analytical potential energy functions using the Murrel-Sorbie potential function. Based on the PECs, the vibrational levels of the four states are determined by solving the Schrodinger equation of nuclear motion, and corresponding spectroscopic constants are accurately calculated. The equilibrium positions as well as the spectroscopic constants and the vibrational levels are reported. By our analysis, the ^3∏ state, of which the dissociation asymptote is Cd（^1S） ＋ Se（^3p）, is identified as a ground state of CdSe dimer, and the corresponding dissociation energy is estimated to be 0.39eV. However, the first excited state is only 1132.49cm^-1 above the ground state and the ^3∑ state is the highest in the four calculated states.

Gravitational Perturbation of Hydrogen Spectrum in the Space Curved by Intense Laser Pulses

The energy level shifts of hydrogen in the space curved by the intense short laser pulses are studied. It shows that for present power level of laser pulses, the magnitude of the energy level shifts in a highly excited hydrogen atom is detectable.

Attenuation-type and failure-type curve models on accumulated pore water pressure in saturated normal consolidated clay

Based on dynamic triaxial test results of saturated soft clay,similarities of variations between accumulated pore water pressure and accumulated deformation were analyzed.The Parr's equation on accumulated deformation was modified to create an attenuation-type curve model on accumulated pore water pressure in saturated normal consolidation clay.In this model,dynamic strength was introduced and a new parameter called equivalent dynamic stress level was added.Besides,based on comparative analysis on variations between failure-type and attenuation-type curves,a failure-type curve model was created on accumulated pore water pressure in saturated normal consolidation clay.Two models can take cycle number,coupling of static and dynamic deviator stress,and consolidation way into consideration.The models are verified by test results.The correlation coefficients are more than 0.98 for optimization of test results based on the two models,and there is good agreement between the optimized and test curves,which shows that the two models are suitable to predict variations of accumulated pore water pressure under different loading cases and consolidation ways.In order to improve prediction accuracy,it is suggested that loading cases and consolidation ways should be consistent with in-situ conditions when dynamic triaxial tests are used to determine the constants in the models.

An eikonal equation based path planning method using polygon decomposition and curve evolution

Path planning is a key technique of autonomous navigation for robots,and the velocity field is an important part.Constructing velocity field in a complex workspace is still challenging.In this paper,an inner normal guided segmentation algorithm in a complex polygon is proposed to decompose the complex workspace in this paper.The artificial potential field model based on probability theory is then used to calculate the potential field of the decomposed workspace,and the velocity field is obtained by utilizing the potential field of this workspace.Path optimization is implemented by curve evolution,during which the internal force generated in the smoothing process of the initial path by a mean filter and the external force is obtained from the gradient of the workspace potential field.The parameter selection principle is deduced by analyzing the influence of several parameters on the path length and smoothness.Simulation results show that the designed polygon decomposition algorithm can effectively segment complex workspace and that the path optimization algorithm can shorten and smoothen paths.

An Efficient Approach to Pulmonary Vessels Extraction Based on Curve Evolution

Pulmonary vessels extraction is a challenging task in clinical medicine. Many pulmonary diseases are accompanied by the changes of vessel diameters. The vessels and their branches, which exhibit much variability, are most important in performing diagnosis and planning the follow-up therapies. In this paper, we propose an efficient approach to pulmonary vessels extraction based on the curve evolution. This approach models the vessels as monotonically marching front under the speed field integrating both the region and the edge information where a new region speed function is designed and integrated with the edge based speed function. Due to the region based speed term, the front could even propagate in small narrow vessel branches. To further improve the segmentation results, a multi-initial fast marching algorithm is developed to fast implement the numerical solution, which may avoid the monotonically marching front leaking out of the weak boundary too earlier and also reduce the computational cost. The validity of our approach is demonstrated by CT pulmonary vessels extraction. Experiments show that the segmentation results by our approach, especially on the narrow thin vessel branches extraction, are more precise than that of the existing method.

小级差需求下基于故障首半波比较的快速电流保护

基于时间级差配合的梯级电流保护受限于出口线路保护动作时间,为缩短保护研判时间,提升配电网多级配合能力,提出一种小级差需求下基于故障首半波比较的快速电流保护方法。对传统电流保护动作时间进行分析,采用整定值构建模板曲线,与故障电流采样值进行多点动态比较,基于有效值爬坡效应及采样值越限效应构建新的保护启动判据、考虑保护算法延迟及干扰点的影响构建新的动作判据,综合加快电流保护判别速度。利用PSCAD/EMTDC软件仿真验证了所提方法在不同类型故障、不同故障时刻、负荷突增、干扰影响等工况下的有效性,结果表明所提方法的动作时间不超过10 ms,有利于小级差更加灵活和可靠的整定。

多年调节综合利用水库多级调度图编制研究

承担多项兴利任务的多年调节水库,需综合考虑入库径流和不同任务要求编制多级调度图。提出了改进典型年法编制多年调节综合利用水库的多级调度图,即对不同来水水平年,根据水库各项兴利任务的设计保证率和年保证供水过程,将综合供水进行对应分级,拟定各级供水过程的供水系数,计算得到多级综合供水过程和年需供水量;利用长系列入库径流资料,根据各级供水任务年需供水量选取典型年,按相应需供水过程进行供水;考虑多年调节水库蓄供水特性,采用不同起调水位编制各调度线,上调度线典型年从蓄水期末水库位于正常蓄水位起调,下调度线和连枯年份调度线典型年从供水期末水库位于死水位起调,逆时序绘制各典型年水库蓄水指示线,分别取上、下包线,得到上、下调度线和连枯年份调度线;通过计算分界库容,拟定不同兴利任务的分界调度线,协调不同兴利任务。综合四条调度线,编制得到多年调节综合利用水库的多级调度图。选取某多年调节综合利用水库,按照流程编制其水库多级调度图,利用调度图进行长系列径流调度,经统计,所编制调度图满足各兴利部门设计保证率要求,多级调度图可有效指导水库运行,提高综合利用水库效益。

基于PS-Level Set的嘴唇几何形状定位模型

针对面向唇读的水平集模型在嘴唇分割中存在边界过收敛和过早收敛的问题,文中提出了一种改进的基于先验知识的水平集模型(简称为PS-Level Set)来进行嘴唇几何形状的定位.PS-Level Set模型利用改进的差值能量函数引入嘴唇形状的先验信息.在曲线演化过程中,反复比较演化曲线和先验曲线的差距,使曲线的演化形状逐渐逼近先验模型形状,从而更精确地收敛于目标物体实际轮廓.实验表明,用PS-Level Set模型定位嘴唇几何形状的准确率比用水平集模型提高了8.38%.

基于混叠模态Lamb波能量衰减特性的液位检测研究

提出了一种利用混叠模态Lamb波检测液位的方法。利用具有单侧液体负载的Lamb波的频散方程求得了相速度频散曲线,分析了波的离面位移和接收信号能量衰减的关系,选择激励了对液位变化敏感的Lamb波模态。仿真计算了不同角度入射波对应的混叠接收时域信号及其对应的能量。实验测试结果表明,包含B4模态波为主的混叠波的检测区分度远高于其他模态混叠波和纵波,该结果与理论计算相符。

基于Level Set方法的曲线演化

Level Set方法是一种描述曲线以曲率相关的速度演化的有力工具,最近几年在医学图像处理、自然现象的模拟以及计算机视觉等领域得到了广泛的应用.其中,曲线演化后的平滑算法和轮廓跟踪方法是Level Set方法实际应用中的两个关键算法.给出了一种平滑Level Set距离函数的简单方法.该方法只采用内插值的方式,消除平面上的全部孤立点以及部分可能产生歧义的点,在允许存在部分冗余点的情况下,利用曲线轮廓跟踪算法,得到平面上所有曲线的轮廓.经过实验验证,该方法简单、高效,适应范围广.

分散决策下分布式光伏储能系统外部性价值量化评估

近年来,随着分布式光伏补贴的逐渐下降和储能技术的日益成熟,分布式光伏储能系统已逐渐成为能源结构转型的关键性环节之一。然而,不同于传统集中式优化规划框架,大规模分布式光伏储能用户分散决策模式下其自利性行为对整体系统运行效率的影响及其外部性价值评估方法仍有待进一步研究。为此,构建了计及分布式光伏储能投资决策的双层模型来模拟需求侧市场成员分散决策行为与系统整体运行的交互关系,以量化分析分布式光伏储能系统的外部性价值。进而,从个体层和系统层两维度设计了市场运营评估指标体系。最后,基于实际系统数据验证了所提模型的有效性。

基于改进的level set嘴唇轮廓定位方法

根据嘴唇的几何分布特性,提出一种基于多方向的水平集方法(Multi-Level set)来进行嘴唇轮廓的定位。Multi-Level set方法通过对嘴唇图像多个方向的滤波得到新的边缘检测函数来增强嘴唇轮廓的梯度信息,然后利用能量函数最小化来使初始曲线向嘴唇轮廓靠近,达到说话人嘴唇轮廓的精确定位。实验证明用Multi-Level set方法定位嘴唇轮廓的准确率比level set提高了7.32%。

双Level Set遥感影像建筑物检测

对传统的基于梯度的Level set方法和基于区域的Chan-Vese分割模型进行分析,提出结合局部梯度和同质区域全局均值信息的双水平集遥感影像分割模型,并利用变分法得到曲线的演化方程。该模型引入一种内部约束能量项近似地表示符号距离函数,使算法摆脱了重新初始化符号距离函数的缺陷,提高了曲线的演化速度,且可以同时分割出多类目标。在建筑物检测中可以同时检测出建筑物的向阳区域、屋顶和阴影区域。实验表明,该方法是一种有效的建筑物检测方法。

洞庭湖生态水位与生态需水量研究

为保护洞庭湖生态系统,基于洞庭湖鹿角、杨柳潭和南咀水文站1961~2020年逐日水位监测数据,开展洞庭湖生态水位和生态需水量的研究。运用天然水位资料法、湖泊形态法、生物空间最小需求法、年保证率法、最低年平均水位法和频率曲线法等6种分析方法计算得出洞庭湖生态水位,利用功能法计算得出洞庭湖生态需水量。结果表明:(1)洞庭湖东、南、西3个湖区最低生态水位分别为24.20,27.78,29.42 m,适宜生态水位分别为25.80,29.07,30.08 m。(2)洞庭湖东、南、西3个湖区最低生态需水量分别为6.31亿,10.02亿,3.83亿m^(3),适宜生态需水量分别为12.66亿,13.99亿,4.61亿m^(3),洞庭湖最低与适宜生态需水量分别为20.16亿m^(3)和31.26亿m^(3)。研究成果可为洞庭湖区域水资源合理配置、湖区生态系统健康运转和洞庭湖治理与保护提供参考依据。

数字化转型程度影响企业风险承担水平机制探讨——基于企业内部控制质量中介效应的实证检验

数字化转型程度关联企业风险承担水平的变化具有其内在规律性。笔者基于企业委托代理理论和内部控制理论,以2010—2020年中国A股非金融行业和非信息产业上市公司的相关有效数据,运用固定效应模型实证检验了企业数字化转型程度与企业风险承担水平之间的关联及其变化。检验结果证实:企业数字化转型程度与企业风险承担水平之间的关联性曲线呈正U型,即企业数字化转型的初始阶段,其风险承担水平随着企业数字化转型程度的提高而降低,而当企业数字化转型达到一定阶段后,企业风险承担水平开始伴随企业数字化转型程度的提高而提高;数字化转型程度对企业风险承担水平的影响通过关键变量——企业内部控制质量发挥中介效应完成;数字化转型程度对企业风险承担水平的影响在不同情境下具有显著的异质性。本研究基于企业内部控制质量中介效应的实证检验,揭示了数字化转型程度对企业风险承担水平的影响机制,研究结论丰富了企业管理创新和企业风险防范相关领域的现有文献,有助于为政府推行数字经济以及企业实施数字化转型提供理论依据。

零知识证明中椭圆曲线运算的硬件加速方法研究

目的:针对零知识证明协议纯软件部署存在的低时延、低功耗服务要求难以满足,以及硬件加速芯片协议适配性差和开发周期长的问题,提出了一种用于零知识证明的椭圆曲线点加计算流式计算架构。方法:实现了点加计算的硬件设计,对高位模运算设计了低时延、可扩展的硬件计算单元,在点加计算的各个计算阶段间规划数据流实现了流水设计,使用OpenCL与HLS,在基于FPGA的异构计算平台上,对不同规模的点乘、多标量乘法计算任务进行了软硬件协同加速。结果:在AMD Xilinx Alevo U50数据中心加速卡上,多标量乘法运算相比于AMD Ryzen 95900X(3.7 GHz)CPU单核及12核运行分别获得了41.5倍及3倍的加速比,硬件加速模块相比于纯软件方式获得了最高12.42倍的能效提升。结论:该计算架构有效提高了硬件资源利用率,降低了椭圆曲线运算时延以及功耗开销。

两种河床式水电站调度曲线的分析与研究

为了分析低水头、日调节或径流式水电站的出力情况,研究适用于水电站的发电调度运行方式曲线,笔者研究分析折线形和山峰形两种出力限制曲线,对两种曲线合理性进行分析和验证,并提出应用建议。结果表明,两种曲线均可以大幅提高水电站及电网调度对短期(日内)预想出力的预测精度。两种曲线均可适用于低水头、径流式水电站在不同水头条件的调度需求,有一定借鉴意义。

基于组合模型的居民消费水平预测

投资、出口、消费是发展经济的“三驾马车”。其中,消费是社会再生产过程中的重要环节,也是最终环节。因此,利用1992年至2021年我国居民消费水平,构建基于模型和二次曲线模型的组合模型,对我国居民消费水平进行预测。结果显示:组合模型的MAPE为2.88%;2022年至2030年我国居民消费水平近似呈直线式增长。