平行连杆单摆式文物隔震装置性能分析

馆藏浮放文物隔震装置可有效减小地震对文物的破坏,而我国在这方面的研发比国外要落后。为保护馆藏浮放文物,开发了一种平行连杆单摆式文物隔震装置,采用理论分析与数值模拟相结合的方法,研究了装置的隔震性能。首先对隔震装置进行了简要介绍,阐述其隔震机理;然后基于动力学相关公式,对隔震装置的效果进行了理论分析,并讨论了不同参数条件的影响;在此基础上,建立了隔震装置的有限元模型,进行了时程分析,获得了文物的位移及加速度响应,评价了装置隔震效果。结果表明:该隔震装置较好地利用了平行连杆的平动原理、杠杆平衡原理及单摆隔震原理,可有效减小文物的地震响应,因而具有良好的隔震效果。后续工作将从试验角度进一步验证及完善该隔震装置性能。更多还原     

建筑隔震技术的研究现状

隔震技术是减小建筑物震灾的一种直接且十分有效的方法,随着地震实例对这种技术的检验,愈来愈显示出隔震装置无比的优越性.本文回顾和分析国内外隔震技术研究的进展,介绍隔震技术的原理和方法、多层橡胶垫和阻尼器的性能以及日本在隔震建筑方面的新进展;隔震层位置的设置、隔震建筑的高度及隔震建筑承受地震作用或强风荷载时的性能仍是需继续研究的课题     

大型渡槽隔震研究

尽管隔震技术已经在实际工程中得到广泛应用,但至今为止,尚无大型渡槽应用隔震技术的实例.本文针对大型渡槽的隔震问题进行研究,探讨大型渡槽的隔震机理、隔震装置和隔震目标,提出隔震渡槽的地震反应分析方法,并结合某实际渡槽工程对各种支承方案下渡槽的地震反应及使用隔震技术后渡槽的减震效果进行具体分析.研究结果表明,应用隔震技术可以显著降低渡槽结构的地震应力反应,提高整体渡槽的抗震性能.     

桥梁结构设计中减隔震技术的有效应用

正随着我国社会建设进程的深入以及经济水平的提升,交通行业获得了迅猛的发展,桥梁建设工程项目的数量和规模在不断增加,也使得桥梁结构设计质量得到了社会各界的广泛关注。而减隔震技术作为桥梁结构设计的重要组成部分,对桥梁整体质量以及功能的发挥有着重要影响。本文简单分析了减隔震技术的原理以及应用现状,并简单阐述了桥梁结构设计中减隔震装置的类型及其应用。减隔震技术主要是利用减震以及隔震装置消减进入桥梁结构的能量,从而确保桥梁整体结构的安全性与稳固性,随着我国公路桥梁事业的不断发展,减隔震技术在桥梁结构设计中得到了广泛的认可和应用。     

基于3D－BASIS－ME摩擦摆隔震系统隔震效果分析

摩擦摆隔震系统（FPS）由于其独特的结构形式,具有限位、自动复位以及通过滑动摩擦消耗地震能量等优点,能有效地减少地震作用对上部结构的影响,隔震效果明显,因此近年来得到广泛的应用。为了更深入地研究摩擦摆隔震系统的隔震效果及其影响因素,基于摩擦摆隔震系统的基本特性与隔震机理,利用隔震计算专用软件3D － BASIS －ME 对隔震框架结构在不同地震波作用下的隔震效果进行了分析计算,与文献试验结果进行对比,发现数值结果与试验结果吻合良好,从而验证了3D － BASIS － ME软件计算的准确性与可行性,在此基础上对不同合成刚度的摩擦摆隔震系统的隔震效果进行数值分析,并确定了隔震效果最佳时,隔震系统的刚度范围,其结论可为实际工程的设计提供参考。     

预压弹簧竖向隔震装置的性能试验与数值模拟

为解决已有的竖向隔震装置无法有效协调承载和隔震双重性能需求的难题,提出一种由预压弹簧装置(pre-pressed spring device, PSD)和黏滞阻尼器构成的阻尼竖向隔震支座(damped vertical isolation bearing, DVIB)。阐明DVIB的构造和工作原理,重点考察其中的PSD的竖向隔震机制。通过组合PSD试件的轴向往复加载试验,验证其多阶段受力-位移特性。利用ABAQUS对上述试件开展精细化有限元建模。研究结果表明,由PSD组成的竖向隔震支座拥有竖向承载所需的高承载力与高刚度,且具备用于竖向隔震的低刚度;上述组合PSD试件的有限元模拟结果与试验结果总体吻合较好,为结构层面的竖向隔震设计与分析提供了实施途径。     

层间隔震结构地震反应分析

层间隔震是一种新的隔震设计思想,它将隔震层设置在建筑物某层柱子和楼板之间进行结构的地震反应控制。介绍了层间隔震在某一工程中的应用,采用ETABS有限元分析程序对其进行了动力非线性时程分析,计算结果表明:层间隔震能有效降低结构的地震反应,隔震层的变形控制在安全的范围之内。     

防震减灾中心工程隔震层以下结构设计

北京市防震减灾中心工程在主楼地上结构采用隔震设计分析。采用MidasGen分析软件,通过时程分析方法,计算工程的隔震效果能否满足规范要求,达到预期的隔震效果。同时采用短柱层模拟隔震层的方法建立计算模型,通过不同模型计算结果的分析对比,探讨采用短柱层模拟隔震层方法的可靠性与准确性,论证该方法进行隔震层以下结构设计计算的可行性。基础隔震概念最早是由日本学者河合浩藏于1881年提出的。隔震对低层和多层建筑较为合适,不隔震时基本周期小于1.0s的建筑结构效果最佳。当隔震层位置设置在首层及首层以上时,隔震体系的特点与基础隔震结构有较大差异,隔震层以下的结构设计计算也较为复杂。1.国内外隔震研究的发展状况     

正渗透西北水窖净水装置

水窖是解决西北缺水地区饮用水困难的常见蓄水设施,其水质优劣将影响水窖的有效利用。目前西北家用水窖水质存在杂质多、细菌超标等问题,现有水窖水净化装置多应用于大型水窖,缺少家用水窖的有效净水装置。在对目前水窖水净化方法对比分析的基础上,提出利用正渗透技术,开发家用水窖净水装置。通过净水实验验证,家用水窖净水装置净化效果好、使用方便、可操作性强。通过分析该装置的技术可行性和经济可行性,表明其结构简单、设计合理、成本低廉,在西北缺水地区具有较好的应用前景。     

软件工程化的负荷特性记录系统开发

对实时运行装置的软件开发采用软件工程方法的可行性与必要性进行了阐述，并对由此开发的软件的实时性和可靠性作了分析。介绍了采用软件工程方法开发的负荷特性记录系统的基本构成和设计思想。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.