Study on dynamic response of embedded long span corrugated steel culverts using scaled model shaking table tests and numerical analyses

A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earth-quakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the cor-rugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground, which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.

Static and Dynamic Analyses of Long-Span Spatial Steel-Cable-Membrane Hybrid Structures

With the increment of the complexity of structural systems and the span of spatial structures, the interactions between parts of the structures, especially between some flexible substructures, become too complex to be analyzed clearly. In this paper, taking an actual gymnasium of a long-span spatial steel-cable-membrane hybrid structure as the calculation model, the static and dynamic analyses of the hybrid structures are performed by employing the global analysis of the whole hybrid structure and the substructural analysis of the truss arch substructure, the cable-membrane substructure, etc. In addition, the comparison of stresses and displacements of structural members in the global and substructural analyses is made. The numerical results show that serious errors exist in the substructural analysis of the hybrid structure, and the global analysis is necessary for the hybrid structure under the excitation of static loads and seismic loads.

Thermal Activation Analyses of Dynamic FractureToughness of High Strength Low Alloy Steels

A formula is derived for determining the influence of temperature and loading rate on dynamic fracture toughness of a high strength low alloy steel (HQ785C) from thermal activation analysis of the experimental results of three-point bend specimens as well as introducing an Arrhenius formula. It is shown that the results obtained by the given formula are in good agreement with the experimental ones in the thermal activation region. The present method is also valuable to describe the relationship between dynamic fracture toughness and temperature and loading rate of other high strength low alloy steels.

Evaluation of Dynamic Soil-Structure Interaction and Dynamic Seismic Soil Pressures Acting on It Subjected to Strong Earthquake Motions

In order to clarify the damage mechanism of the subway structure, the dynamic soil-structure interaction and the dynamic forces acting on the structure, a series of shaking table tests and simulation analyses were performed. The seismic response of the structure and the dynamic forces acting on the structure due to sinusoidal and random waves were investigated with special attention to the dynamic soil-structure interaction. The result shows that the compression seismic soil pressures and extension seismic soil pressures simultaneously act on the sidewalls, and big shear stress also acts on the ceiling slab due to horizontal excitation. The seismic soil pressure could be approximated to hyperbola curve, and reached a peak value with increase of the shear strain of the model ground. In addition, a slide and exfoliation phenomenon between the structure and the surrounding ground was simulated, using the nonlinear analyses. The foundation is provided for amending the calculation method of seismic soil pressure and improving the anti-earthquake designing level of underground structure.

A DYNAMIC ECG MONITORING AND RECORDING SYSTEM

This peper proposes a new type of dynamic ECG (Holier) monitoring andrecording system based on technology or computer controlling and high storage capacitydynamic RAM (DRAM). The system realizes the monitoring and recording ECG signalscontinuously up to 24 hours with the double error criterion ECG data compression algorithm or time error and amplitude error[1], adaptive algorithm for detecting andanalysing the oRS complexes[2] and the technology of high storage capacity DRAM. Itsadvantages are high storage Capacity (4MB), low power dissipation (less titan 30mA).

Parametric analyses on dynamic stall control of rotor airfoil via synthetic jet

The effects of synthetic jet control on unsteady dynamic stall over rotor airfoil are investigated numerically. A moving-embedded grid method and an Unsteady Reynolds Averaged Navier-Stokes（URANS） solver coupled with k-x Shear Stress Transport（SST） turbulence model are established for predicting the complex flowfields of oscillatory airfoil under jet control. Additionally, a velocity boundary condition modeled by sinusoidal function has been developed to fulfill the perturbation effect of periodic jet. The validity of present CFD method is evaluated by comparisons of the calculated results of baseline dynamic stall case for rotor airfoil and jet control case for VR-7 B airfoil with experimental data. Then, parametric analyses are conducted emphatically for an OA212 rotor airfoil to investigate the effects of jet control parameters（jet location, dimensionless frequency, momentum coefficient, jet angle, jet type and dual-jet） on dynamic stall characteristics of rotor airfoil. It is demonstrated by the calculated results that efficiency of jet control could be improved with specific momentum coefficient and jet angle when the jet is located near separation point of rotor airfoil. Furthermore, the dual-jet could improve control efficiency more obviously on dynamic stall of rotor airfoil with respect to the unique jet, and the influence laws of dual-jet＇s angles and momentum coefficients on control effects are similar to those of the unique jet. Finally,unsteady aerodynamic characteristics of rotor via synthetic jet which is located on the upper surface of rotor blade in forward flight are calculated, and as a result, the aerodynamic characteristics of rotor are improved compared with the baseline. The results indicate that synthetic jet has the capability in improving aerodynamic characteristics of rotor.

北极海冰模型研究进展综述

海冰模式是目前国内外北极海冰历史重建、机制分析与预测未来演变的重要工具。通过比较主流海冰模式的关键参数化方案设置的异同,包括主要的热力学与动力学过程、海冰厚度再分布归纳了当前海冰模式的改进情况,回顾了海冰模式结果对于北极关键区域季节变化、年际差异与极端事件成因分析所提供的支持;最后,提炼出海冰模式未来发展的方向,为我国北极海冰模式构建与发展、北极海冰快速变化机制研究和北极海冰精细化预报工作提供参考。

山东港口大厦结构设计

山东港口大厦采用钢管混凝土柱-钢梁-钢筋混凝土核心筒混合结构体系,角部6根斜钢管混凝土柱由下至上逐层缩进,与向上收紧的风帆形态相呼应。结构存在各层楼板局部不连续、跃层柱和高度超限等不规则项,按C级抗震性能目标进行性能化设计,采用SAUSAGE进行罕遇地震作用下的弹塑性分析,找出结构薄弱部位和构件,并采取针对性的抗震加强措施。空中大堂采用“刚柔结合”的钢-索网幕墙体系,介绍了支撑幕墙的主体结构。采用ANSYS对钢管混凝土柱斜柱变直柱节点进行了有限元分析。分析结果表明结构抗震性能良好,满足设定的抗震性能目标。

地震作用下某框架钢结构桥梁的地震动力响应分析

分析结构的地震动反应是进行结构抗震设计的基础。本文对威海某复杂钢框架桥梁结构在不同地震荷载作用下的动力响应进行了有限元分析。为更加清楚地分析结构的地震动反应及破坏机理,提高桥梁结构的抗震性能,本文采用时程分析法,按要求选用了1条人工模拟地震波和2条天然地震波作为地震动输入。在动态分析的基础上,分别计算该桥梁的最大应力和最大挠度。研究发现:在地震作用下,支撑体系及其端部两柱之间的梁是钢结构桥梁的关键构件;结构的最大位移位于钢结构桥端部的悬挑梁处。数值计算结果表明:该钢框架桥分别在X轴方向和Y轴方向输入地震波时,其动态响应不同,但该结构在地震作用下是安全的。

摩托车车架动态特性分析

利用有限元方法对摩托车车架动态特性进行了分析计算 ,并通过实验模态方法进行了相应的实验验证 ,获得了车架模态参数和振型。分析了路面和发动机激励对车架动态特性的影响 ,在考虑到实际安装位置和投入成本的情况下 ,对摩托车车架结构进行了改进 ,在车架尾部和座垫支架左右之间各加一块钢板。在同样的实验条件下 ,对改进摩托车车架动态特性效果进行了实验验证 ,提高了摩托车的乘坐舒适性 。

一种新型旋风分离器气相流场实验研究和数值模拟

对适用于高温高压下的一种新型旋风分离器的气相流场用粒子动态分析仪(PDA)进行了测试。并且用计算流体力学(CFD)软件中的不同湍流模型对其流场进行了数值模拟,得出了该旋风分离器不同的结构和操作条件对其流场的影响规律,同时也找到了适合模拟该种旋风分离器流场的湍流模型——雷诺应力模型(RSM)。

污点分析技术的原理和实践应用

信息流分析可以有效保证计算机系统中信息的保密性和完整性,污点分析作为其实践,被广泛用于软件系统的安全保障技术领域.对近些年来面向解决应用程序安全问题的污点分析技术进行综述:首先,总结了污点分析的基本原理以及在应用中的通用技术,即,使用动态和静态的方法解决污点传播;随后,分析该技术在移动终端、互联网平台上的应用过程中遇到的问题和解决方案,包括解决Android应用隐私泄露与检测Web系统安全漏洞的污点分析技术;最后,展望该技术的研究前景和发展趋势.

动态机械热分析技术在高聚物性能研究中的应用

分析动态机械热分析仪的原理 。

轻质油藏高压注空气加速量热分析实验研究

研究了鄯善轻质油藏实施注空气提高采收率的可行性,进行了鄯善油田原油同空气接触的加速量热分析实验研究,研究了高压注空气提高采收率时鄯善轻质油藏油样在油藏条件下能否自燃的问题,获得了原油与空气反应的动力学参数。研究表明,在油藏温度和压力下,鄯善轻质油藏油样等温老化7.6天后仅使温度增加8～10℃,没有观测到自燃;实际油藏能保持较好的绝热条件,在加速量热分析等温老化中没有观测到自燃并不排除在现场条件下可能发生自燃;鄯善油样与空气的氧化反应,在150～350℃有很高的反应速率,存在键断裂反应;油-空气0级反应的活化能为73.0kcal/mol。研究结果为今后开展注空气设计、优化注空气工艺提供理论和技术依据。

地层沉陷的数值模拟应用研究

系统地总结了近些年来，应用有限元、离散元等数值分析方法研究开采引起地层沉陷的一些成果，用有限单元法分析了辽源矿务局西安煤矿立井保护煤柱开采引起的井筒变形和滑移，在断层与井筒交界处，井筒发生了错动，且周围明显呈现塑性破坏区；用离散单元法研究了地下开采引起地层沉陷的动态发展过程，对指导建（构）筑物下开采具有重要意义。并且表明数值模拟方法对分析含构造岩体地表沉陷是行之有效的。

浓香型白酒糟醅发酵过程中香气成分的变化趋势

采用气相和液相色谱分析方法,跟踪调查了浓香型白酒发酵过程中,糟醅所含酸醛醇酯等各类香气成分的动态变化及其相互关系。研究发现糟醅中乙酸、丁酸、己酸和乳酸的变化趋势与对应的乙酯生成趋势大体一致。但各类香气成分的含量比例及其变化趋势,在糟醅中与在白酒产品中却存在一定的差异性。本文揭示如何增加糟醅中的己酸和降低乳酸,以及进一步弄清白酒蒸馏机理,是提高白酒生产质量的重要技术问题。

基于遥感技术的生态系统服务价值动态评估模型研究

以甘肃省草地生态系统为例,利用多学科的知识综合发展了一个针对生态系统服务价值评估的动态模型,提出了一种适宜于地区性评估技术的单位价值计算方法,并构建以生物量比值系数以及货币变化指数为调节因子的动态监测模型结构.选择建立在植被机理基础上的CASA模型,模拟植被所吸收的光合有效辐射、植被层对入射光合有效辐射等,利用遥感技术反演了甘肃省年际植被净初级生产力NPP,并进行了验证.根据建立的动态模型分别评估了1999年和2002年甘肃省草地生态系统服务价值.结果表明:1985年甘肃省草地生态系统服务价值为283.6×108元,1999年为1 403.7×108元,2002达到1 308.6×108元,全省草地生态系统服务价值呈现逐步增加的趋势.生态系统服务价值存在地域性特征并随时间而变化,目前的生态系统服务价值评估研究存在着众多不确定因素,进一步加快定量化研究深度,同时寻找有效的验证方法将是未来生态学乃至其它相关学科研究的重要主题之一.

大理岩和砂岩动态本构的实验研究

探讨了在Ｈｏｐｋｉｎｓｏｎ压杆装置上进行岩石长杆冲击实验。用多组埋入式聚偏四氟乙烯薄膜应力计，进行了波衰减的测量，获得了大理岩、砂岩在干燥、饱水、饱油情况下的衰减系数。对实测波形运用拉格朗日分析和路径线方法获取了大理岩、砂岩动态本构关系。

液固两相饱和介质动力分析的一种显式有限元法

以经典的Biot液固两相饱和介质动力理论为基础,建立了以固相位移和液相位移为未知量的液固两相饱和介质动力分析的一种显式有限元法。该显式方法克服了隐式方法需要求解联立方程组的缺点,具有节省计算机内存空间和计算时间的优点,可以方便地应用于求解大自由度和介质非线性问题。算例分析表明,该方法具有较高的计算精度。

吉林省中西部棉铃虫发生规律及虫源分析

近年来,棉铃虫在吉林省各地区玉米田为害,成为了潜在的玉米穗部重要害虫。明确棉铃虫在吉林省的种群动态、虫源性质,对其早期预警与综合防控具有重要意义。本研究在吉林省中西部的公主岭市,综合运用常规监测、卵巢解剖、田间调查、气象分析、轨迹分析等技术和方法,对棉铃虫的发生时间、发生世代、虫源地、迁飞情况进行了初步研究。结果表明,8月上旬-10月上旬为棉铃虫成虫发生期,其中8月中旬-9月下旬是发生高峰期。棉铃虫成虫在当地发生2代(第3代和第4代),第3代为迁入世代,第3代高峰期的虫源主要来自于辽宁省部分地区。第4代主体为本地繁殖世代,其为害期正值当地玉米灌浆至蜡熟期。第4代棉铃虫成虫羽化后滞留本地的种群因气候以及食物原因而消亡。迁出期的风向不利于棉铃虫种群回迁。