深隧排水折板型竖井泄流消能的试验研究

针对深隧排水系统竖井泄流过程中高速气-水两相流动特性进行了水力模型试验研究,观测竖井内水流下泄过程中的型态,分析最大泄流量与折板间距的关系,计算不同工况下的竖井消能率,并揭示折板型竖井在泄流过程中的消能机理. 试验结果表明:竖井在泄流过程中存在3种水流型态:撞壁受限流、临界流和自由跌水流;泄流过程中水跃是水流在折板上消能的主要原因,水流流至井底与反向流体互相撞击破碎使竖井达到最终消能的目的;当竖井直径D = 0.4 m、折板间距d介于16.02～24.56 cm时,竖井最大泄流量介于（8.7～14.7） × 10?3 m3/s,且d与最大泄流量Q_m存在线性关系;根据能量守恒定律推导出消能率公式,得到d = 19.4 cm、倾角θ = 10° 时的竖井消能率为最优;竖井盖板开孔直径 Ф 对竖井顶部压强的影响较大,当 Ф ≥ 4 cm时,竖井顶部相对压强基本为0,并且具有一定倾角的折板有利于加速竖井的泄流过程;上、中、下折板冲击力（F_u、F_m、F_d）呈现F_u > F_m > F_d 的分布规律,上、中、下折板最大面荷载分别为42.8、30.7、22.8 kN/m2. 深隧排水折板型竖井最佳泄流量和最优消能率的试验研究成果对深隧竖井工程的设计与运行提供了一定参考价值.      

NEW WIND-INDUCED RESPONSES ANALYSIS METHOD OF SPATIAL STRUCTURES IN FREQUENCY DOMAIN WITH MODE COMPENSATION

IntroductionIn response to the demand for architecture anduse function,the span of stadiums or gymnasiumsis enlarging,which inevitably tends to involvelight- weigh roofs,such as membrane.Thesestructures with long natural periods is sensitive towind vibrations,therefore the effects of windloads,especially of dynamic wind loads,are be-coming significant at their design stage.It isknown that these types of structures are apt tohave many natural frequencies in a narrow frequen-cy range.This fact d…     

Radar Emitter Signal Recognition Based on Complexity Features

Intra-pulse characteristics of different radar emitter signals reflect on signal waveform by way of changing frequency, phase and amplitude. A novel approach was proposed to extract complexity features of radar emitter signals in a wide range of signal-to-noise ratio ( SNR), and radial basis probability neural network (RBPNN) was used to recognize different radar emitter signals. Complexity features, including Lempel-Ziv complexity (LZC) and correlation dimension (CD), can measure the complexity and irregularity of signals, which mirrors the intra-pulse modulation laws of radar emitter signals. In an experiment, LZC and CD features of 10 typical radar emitter signals were extracted and RBPNN was applied to identify the 10 radar emitter signals. Simulation results show that the proposed approach is effective and has good application values because average accurate recognition rate is high when SNR varies in a wide range.     

Superconducting Energy Storage Flywheel——An Attractive Technology for Energy Storage

Flywheel energy storage(FES) can have energy fed in the rotational mass of a flywheel,store it as kinetic energy,and release out upon demand.The superconducting energy storage flywheel comprising of magnetic and superconducting bearings is fit for energy storage on account of its high efficiency,long cycle life,wide operating temperature range and so on.According to the high temperature superconducting(HTS) cooling mode,there are zero field cooling(ZFC) bearings and field cooling(FC) bearings.In practice,th...     

Computational Fluid Dynamics Uncertainty Analysis for Simulations of Roll Motions for a 3D Ship

The roll motions are influenced by significant viscous effects such as the flow separation.The 3D simulations of free decay roll motions for the ship model DTMB 5512 are carried out by Reynold averaged NavierStokes(RANS) method based on the dynamic mesh technique.A new moving mesh technique is adopted and discussed in details for the present simulations.The purpose of the research is to obtain accurate numerical prediction for roll motions with their respective numerical/modeling errors and uncertainties.Errors and uncertainties are estimated by performing the modern verification and validation(VV) procedures.Simulation results for the free-floating surface combatant are used to calculate the linear,nonlinear damping coefficients and resonant frequencies including a wide range of forward speed.The present work can provide a useful reference to calculate roll damping by computational fluid dynamics(CFD) method and simulate a general ship motions in waves.     

中强白噪声对豚鼠内耳的损害——动物试验研究之一

<正> 噪声是国际重大公害,到处存在,多方危害于人,唯听觉器官首当其冲,常酿成耳聋。噪声耳聋的根本问题在预防,防护之本在降低其强度;欲达到此目的需耗费巨额资金,至今世界各国均难完全办到,故不得不辅以个人防护;个人防护办法不少,可惜迄今尚乏真正方便,舒适而有效者,究其原因,实与其发病机制,及病理改变尚未被彻底探明有关。为此我们设计了一组试验拟观察在中强噪声间断作用下豚鼠内耳感觉装置的损害规律,现将其部分结果总结报告如下。     

Regenerative braking algorithm for an ISG HEV based on regenerative torque optimization

A novel regenerative braking algorithm based on regenerative torque optimization with emulate engine compression braking (EECB) was proposed to make effective and maximum use of brake energy in order to improve fuel economy. The actual brake oil pressure of driving wheel which is reduced by the amount of the regenerative braking force is supplied from the electronic hydraulic brake system. Regenerative torque optimization maximizes the actual regenerative power recuperation by energy storage component, and EECB is a useful extended type of regenerative braking. The simulation results show that actual regenerative power recuperation for the novel regenerative braking algorithm is more than using conventional one, and life-span of brake disks is prolonged for the novel algorithm.     

Influence of nonassociativity on the bearing capacity factors of a circular footing

Numerical computations using the finite difference code FLAC (fast Lagrangian analysis of continua)are presented to evaluate the soil bearing capacity factors N'c, N'q and N'r for circular smooth and rough footings.The influence of nonassociative flow rule on the ultimate bearing capacity of a circular footing is investigated. The footing rests on the surface of a homogeneous soil mass and a Mohr-Coulomb yield criterion have been assumed for the soil behavior. The values of ultimate bearing capacity factors N'c, N'q and N'r are obtained for a wide range of values of the friction angle for five different values of the dilation angle. The values from the numerical simulation are found to decrease significantly with the increase of nonassociativity of the soil. The results are compared with those derived from existing classical solutions.     

高速列车气动噪声数值仿真

建立了高速列车组包括头车、中间车、尾车及外部空间在内的气动噪声计算物理模型,从声学理论出发,结合列车实际运行的边界条件,运用以稳态结果作为初始值进行瞬态计算,预测了高速列车气动噪声,并对采用直接瞬态法计算气动噪声的可行性进行了分析计算.研究结果表明气动噪声分布于很宽的频带内,无明显的主频,属于宽频噪声.在低频中气动噪声...     

盾构隧道联络横通道的振动台试验与数值模拟

联络横通道与隧道主体形成的空间交叉结构是隧道抗震的薄弱环节. 为探讨联络横通道采用刚、柔两种连接形式时对盾构隧道地震响应的影响,以相似理论为基础,通过室内土工试验确定了振动台试验中地层和结构相似模型的材料参数及配比,分别建立了振动台试验结构模型和数值分析模型;将第1组试验得到的地层卓越频率15.0 Hz作为其余试验工况和数值计算中地震动频率的输入依据,通过试验和数值计算相结合分析的方法对主隧道与联络横通道的地震响应规律进行了研究. 研究结果表明:结构与相同深度位置地层的加速度响应变化规律基本相同,离地面越近,地层加速度的放大效应越明显;联络横通道采用刚性连接时,其最大应变反应出现在结构的拱顶和两侧拱脚处,而采用柔性连接可较好的降低结构各处的应变反应,且输入地震峰值加速度越大其减弱效果越明显;主隧道横断面上,靠近联络横通道连接处的位置易受其影响而产生应力突变,采用刚性连接时,其受到的影响更大;振动台试验与数值结果规律基本一致,采用刚性连接时,联络横通道对主隧道纵向的影响范围约为3.0倍联络横通道宽度,而采用柔性连接时其影响范围则减小至1.5～2.0倍.      

Numerical study on vortex induced vibration of a flexible plate behind square cylinder with various flow velocities

The vortex induced vibration （VIV） of a flexible plate behind the square head with various flow velocities is simulated. The closely coupling approach is used to model this fluid-structure interaction problem. The fluid governed by the incompressible Navier-Stokes equations is solved in arbitrary Lagrangian-Eulerian （ALE） frame by the finite volume method. The structure described by the equations of the elastodynamics in Lagrangian representation is diseretized by the finite element approach. The numerical results show that the resonance occurs when the frequency of vortex shedding from square head coincides with the natural frequency of plate. And tile amplitude of both the structure motion and the fluid load keeps increasing with the time. Furthermore, it is also found that in particular range of flow velocity the vibration of the plate would reach a periodical state. The amplitude of plate oscillating increases with the growth of velocity, while the frequency is locked.     

Finite Element Simulation of Processes Involving Moving Heat Sources. Application to Welding and Surface Treatment

IntroductionAwiderangeofweldingorsurfacetreatmentprocessesinvolvetheuseofaheatsourcemovingataconstantspeedoverthesurfaceofthecomPonent.ThreedimensionalcomPutationofresidualstressesanddistortionsinducedbythiskindofprocesses,usingtheusualfiniteelementmethod,needsveryrefinedmeshesinordertocorrectlydescribethepropertiesandstressgradientsintheheataffCctCdzonealongthepathoftheheatsource.Inthispaper,wediscussthedifferentnumericalaPproaches,imPlementedinSYSWELD@software,whichcanbeusedtodorealisti…     

基于霍夫蕨的实时对象跟踪方法

基于霍夫变换方法难以在保持高检测精度的同时满足跟踪的实时性,且难以适应初始训练样例十分有限的情况,为解决上述问题,提出一种基于霍夫蕨的对象跟踪方法.该方法以随机蕨作为基础检测结构,将对象的局部表观作为学习数据,在其每个叶节点中计算并保存霍夫空间中属于目标对象的投票概率,在运行时通过在线学习该检测器和对象模型,适应对象表观的变化.结合对TLD跟踪框架的改进,实现了无约束环境下长时间的可视跟踪.在Babenko视频序列集上的实验结果表明,提出的对象跟踪方法在普通PC上的平均运行速率为3帧/s,平均准确率为87.1%,总体上优于现有的跟踪方法.      

基于能量的网壳结构协调抗震性能分析

为了揭示地震作用下网壳结构各局部间受力状态及该变化与结构承载能力间的关系,对有限元全荷载域动力时程分析应变能数据进行了再建模,在此基础上应用能量参数系统研究了地震作用下网壳结构各杆件内力重分布.研究结果表明,网壳结构在工作状态下各单元间能够协调、稳定地共同承担外荷载;当结构失效后,各单元间协调变形的稳定性被破坏,基于协调变形可以判断网壳结构的工作状态;在水平向动荷载作用下,单层网壳中下部指数应变能较大,径杆最大值出现在第5环,约为第1环的13倍;三向地震波作用下,中上部指数应变能较大,径杆最大值出现在第2环,约为第6环的15倍.      

落石冲击力评定的离散元颗粒流数值模拟

为使落石冲击力评定更合理、有效,以离散元模型(DEM)为理论基础,利用颗粒流(PFC)单元法研究垂直下落条件下落石对结构的冲击力,分析了落石高度、重力及回填土厚度对冲击力的影响规律.将PFC数值模拟结果与其他几种落石冲击力计算方法所得结果进行比较,结果表明:落石冲击力与落石高度及重力均呈明显的线性关系,落石冲击力随落石高度线性变化幅度与落石重力有关,而落石冲击力随落石重力线性变化幅度与回填土厚度有关;回填土厚度为0.6 m时的冲击力比无回填土时减小50%~60%,回填土厚度大于2.0 m时,缓冲幅度趋于稳定,说明回填土厚度有一个合理范围,超出时,结构总荷载会增大;离散元颗粒流数值模拟方法通过阻尼设置来模拟空气在落石下落过程中产生的作用,使得在评定大体积落石从较高高度下落时产生的冲击力更加合理.      

复杂断面地铁隧道开挖优化及对建筑物的影响

基于FLAC3D,建立了复杂断面隧道和建筑物的三维数值模型,以沉降量和结构应力最小为优化目标, 对5种工法方案进行了优化,以确定最优工法.用最优工法开挖隧道,预测开挖引起的塑性破坏区,并提出有针 对性的预加固措施.在对塑性破坏区进行预加固的条件下,预测各开挖段地表和建筑物基础的沉降特征及最大 沉降量,对比分析地表沉降曲面与建筑物基础沉降曲面的差异,评价整个开挖过程中建筑物和隧道关键结构的 安全性.数值模拟结果与实测数据规律一致,为复杂断面地铁隧道开挖的环境控制提供了重要的技术支持.      

直线型公交停靠站通行能力计算方法

为了提高公交停靠站通行能力计算方法的精确性,针对目前城市的公交运行现状,使用时空分布图分析了公交车在直线式停靠站的服务过程,在此基础上,综合考虑停靠站排队概率和停靠时间分布,推导了公交停靠站通行能力计算模型.对杭州市公交车停靠时间的分布函数进行了拟合,对数正态分布的拟合程度最优, 2个交通时段的K-S检验值分别为0.083 9和0.050 6.用MATLAB编程得到不同分布参数下的通行能力结果表明:随着停靠时间对数平均值μ的增加,不同泊位数停靠站的通行能力减少了44.4%~47.3%;通过VISSIM仿真得到了停靠站的通行能力,模型计算值与仿真结果的平均误差为6.5%.      

自然对流影响结冰的数值模拟及实验研究

为了了解在结冰过程中水的自然对流对蓄冰桶内温度分布的影响以及水的实际的流动情况,利用数值模拟软件对竖直铜管结冰过程进行了研究,通过实验对数值模拟得出的温度分布进行了验证。从数值模拟计算得出:靠近管壁的底角出现了和主流区流动相反的漩涡,且随着时间的推移漩涡不断向上移动;纵向温度分布出现了翻转现象,径向温差很小;且密度翻转现象对冰层的轮廓有影响,使得冰层出现倒锥形。     

热再生沥青混合料低温抗裂性能全程评价

为了评价热再生沥青混合料全寿命周期内的低温抗裂性能,以含有不同比例RAP的再生沥青混合料为研究对象,通过STOA和LTOA试验模拟混合料在不同使用阶段的老化,以极限应变和应变能密度为指标,采用低温弯曲试验对再生沥青混合料的低温抗裂性能进行了评价.试验结果表明:RAP 含量低于40% 的再生沥青混合料的低温抗裂性能与普通沥青混合料相当;受再生剂扩散作用的影响,STOA 后再生沥青混合料低温抗裂性能变化幅度较小,LTOA 过程中低温抗裂性能的变化规律与普通混合料相近;RAP 含量达 50% 时,再生沥青混合料老化前后的低温抗裂性能均较差.     

双馈感应发电机动态模型的研究

从电机学基本原理出发，建立了用电压源代替转子绕组电气注入的双馈感应发电机3阶动态模型．该模型阶数较少，物理意义明确，适用于描述调速范围较大的双馈感应发电机，例如大型变速恒频风力发电机组中的双馈感应发电机，并且应用MATLAB对该动态模型进行了仿真研究，仿真结果表明了该模型的正确性。