Experimental and theoretical study on vibration control of base-isolation with energy transducer

In order to evaluate the effects of structural control and energy transition for the base-isolation with energy transducer （BIET）, shaking table tests on a steel frame model （BIET system） with scale of 1：4 were conducted and the results were compared with the lead rubber beating （LRB） isolation system for the same model. Then numerical analysis of the system was carried out, in which the improved Wen analytic model was used to simulate the hysteretic law of transducers. The results show that the structural system can transform the partial earthquake energy to hydraulic energy ; furthermore, the effect of structural control can reach or be close to that of the LRB isolation system. The agreements between numerical analysis results and those of shaking table tests demonstrate the accuracy of the numerical model.

Effects of Strain Rate and Fiber Content on the Dynamic Mechanical Properties of Sisal Fiber Cement-Based Composites

In this paper,a split Hopkinson pressure bar(SHPB)was used to investigate the dynamic impact mechanical behavior of sisal fiber-reinforced cement-based composites(SFRCCs),and the microscopic damage evolution of the composites was analyzed by scanning electron microscopy(SEM)and energy-dispersive X-ray spectrome-try(EDS).The results show that the addition of sisal fibers improves the impact resistance of cement-based composite materials.Compared with ordinary cement-based composites(OCCs),the SFRCCs demonstrate higher post-peak strength,ductility,and energy absorption capacity with higher fiber content.Moreover,the SFRCCs are strain rate sensitive materials,and their peak stress,ultimate strain,and energy integrals all increase with increasing strain rate.From the perspective of fracture failure characteristics,the failure of OCCs is dominated by the brittle failure of crystal cleavage.In contrast,the failure mode of the SFRCCs changes to microscale matrix cracks,multi-scale pull-out interface debonding of fibers(fine filaments and bundles),and mechanical interlock.This research provides an experimental basis for the engineering application of high-performance and green cement-based composites.

The SLA （Second Law Analysis） in Convective Heat Transfer Processes

In all convective heat transfer situations, losses occur in the flow field （by dissipation） as well as in the temperature field （by conduction）. Typically these losses are more or less quantified by the friction factorfwith respect to losses in the flow field, and the Nusselt number Nu for the heat transfer quality. Assessing the process of convective heat transfer as a whole, then becomes problematic because two different non-dimensional quantities, f and Nu, have to be combined somehow. From a thermodynamics point of view, there is a reasonable alternative： Since all losses become manifest in corresponding entropy generation rates, these rates are determined in the velocity as well as in the temperature field. Based on the integration of the entropy generation fields, an energy devaluation number is introduced. It basically determines how much oftbe so-called entropic potential of the energy involved in a convective heat transfer process is used within it. This approach is called SLA （second law analysis）.

Experimental and simulation studies on similitude design method for shock responses of beam-plate coupled structure

The similitude theory helps to understand the physical behaviors of large structures through scaled models. Several papers have studied the similitude of shock issues. However, the dynamic similitude for shock responses of coupled structures is rarely incorporated in open studies. In this paper, scaling laws are derived for the shock responses and spectra of coupled structures. In the presented scaling laws, the geometric distortion and energy loss are considered. The ability of the proposed scaling laws is demonstrated in the simulation and experimental cases. In both cases, the similitude prediction for the prototype's time-domain waveform and spectrum is conducted with the scaled model and scaling laws. The simulation and experimental cases indicate that the predicted shock responses and spectra agree well with those of the prototype, which verifies the proposed scaling laws for predicting shock responses.

Simplified Step-by-Step Nonlinear Static Program Investigating Equilibrium Conditions of Electrons in Atom and Ionization Energies: Case Study on Argon

For investigation of equilibrium conditions of electrons in an atom, and Ionization Energies of Elements, a simplified deterministic static model is proposed. The electrons are initially uniformly and sparsely arranged on the outer surface of nucleus. Then, by taking into account the nucleus-electron interaction (attractive and repulsive) and the mutual electron-electron repulsions, and by a simple step-by-step nonlinear static analysis program, all the electrons are found to equilibrate on the outer surface of the same sphere, which is concentric and larger than nucleus. In a second stage, starting from an equilibrium sphere of electrons, one of the electrons is subjected to gradual forced removal, radially and outwards with respect to nucleus. Within each removal step, the produced work increment is determined and the increments are summed. When no more significant attraction is exerted by nucleus to removed electron, the total work gives the Ionization Energy. After removing of single electron, the remaining electrons fall on a lower shell, that is, they equilibrate on the outer surface of a smaller concentric sphere. For nucleus-electron interaction, an L-J (Lennard-Jones) type curve, attractive and repulsive, is adopted. When the parameter of this curve is n > 1.0, the Ionization Energy exhibits an upper bound. As parameter n increases from 1.0 up to 2.0, the attractive potential of L-J curve is gradually weakened. The proposed model is applied on Argon. It is observed that, as the number of electrons increases, the radius of equilibrium sphere increases, too, whereas the attractive nucleus-electron potential is reduced;thus the Ionization Energy is reduced, too. Particularly, as the number of electrons and the radius of equilibrium sphere exceed some critical values, the above two last quantities exhibit abrupt falls. A regular polyhedron is revealed, which can accommodate Elements up to atomic number Z = 146, that is 28 more than Z = 118 of existing last Element, as guide for initial locations of electrons in the above first program.

Carnot Factor of a Vapour Power Cycle with Regenerative Extraction

The present paper describes the energy analysis of a regenerative vapour power system. The regenerative steam turbines based on the Rankine cycle and comprised of vapour extractions have been used industrially since the beginning of the 20th century, particularly regarding the processes of electrical production. After having performed worked in the first stages of the turbine, part of the vapour is directed toward a regenerative exchanger and heats feedwater coming from the condenser. This process is known as regeneration, and the heat exchanger where the heat is transferred from steam is called a regenerator (or a feedwater heater). The profit in the output brought by regenerative rakings is primarily enabled by the lack of exchange of the tapped vapour reheating water with the low-temperature reservoir. The economic optimum is often fixed at seven extractions. One knows the Carnot relation, which is the best possible theoretical yield of a dual-temperature cycle;in a Carnot cycle, one makes the assumption that both compressions and expansions are isentropic. This article studies an ideal theoretical machine comprised of vapour extractions in which each cycle partial of tapped vapour obeys these same compressions and isentropic expansions.

Second law analysis of Blasius flow with nonlinear Rosseland thermal radiation in the presence of viscous dissipation

In the present article,we perform the second law analysis of classical Blasius flow accounting the effects of nonlinear radiation and frictional heating.The two-dimensional boundary layer momentum and energy equations are converted to self-similar equations using similarity transformations.The set of resultant ordinary differential equations are solved numerically.The numerical results obtained from solutions of dimensionless momentum and energy equations are used to calculate the entropy generation number and Bejan number.The velocity profile f'(ξ),temperature distributionθ(ξ),entropy production number Ns and Bejan number Be are plotted against the physical flow parameters and are discussed in detail.Further,for the sake of validation of our numerical code,the obtained results are reproduced using Matlab built-in boundary value solver bvp4c resulting in an excellent agreement.It is observed that entropy generation is increasing function of heating parameter,Prandtl number,Eckert number and radiation parameter.Further,it is observed that entropy generation can be minimized by reducing the operating temperatureΔT=T_(w)−T_(∞).

A local energy-preserving scheme for Klein Gordon Schrdinger equations

A local energy conservation law is proposed for the Klein--Gordon-Schrrdinger equations, which is held in any local time-space region. The local property is independent of the boundary condition and more essential than the global energy conservation law. To develop a numerical method preserving the intrinsic properties as much as possible, we propose a local energy-preserving （LEP） scheme for the equations. The merit of the proposed scheme is that the local energy conservation law can hold exactly in any time-space region. With the periodic boundary conditions, the scheme also possesses the discrete change and global energy conservation laws. A nonlinear analysis shows that the LEP scheme converges to the exact solutions with order O（τ2 ＋ h2）. The theoretical properties are verified by numerical experiments.

Approach in High Precision Topic-Specific Resource Discovery on the Web

The Internet presents numerous sources of useful information nowadays. However, these resources are drowning under the dynamic Web, so accurate finding user-specific information is very difficult. In this paper we discuss a Semantic Graph Web Search (SGWS) algorithm in topic-specific resource discovery on the Web. This method combines the use of hyperlinks, characteristics of Web graph and semantic term weights. We implement the algorithm to find Chinese medical information from the Internet. Our study showed that it has better precision than traditional IR (Information Retrieval) methods and traditional search engines. Key words HITS - evolution web graph - power law distribution - context analysis CLC number TP 391 - TP 393 Foundation item: Supported by the National High-Performance Computation Fund (00303)Biography: Ye Wei-guo (1970-), male, Ph. D candidate, research direction: Web information mining, network security, artificial intelligence.

我国主要河川径流演变规律与归因及其区域特征

从径流演变规律主要分析方法和主要河川径流演变规律、径流主要归因方法和主要河川径流归因分析、案例分析、我国主要河川径流演变规律与径流归因分析区域分布特征4个方面系统总结和梳理了我国近年来在主要河川径流演变规律与归因及其区域特征研究方面取得的主要研究成果。结果表明:Mann-Kendall非参数趋势检验方法是较为常用的径流演变规律分析方法,水文模型法、统计分析方法和Budyko假设的流域水热耦合平衡方法是进行径流变化归因分析的常用方法,其中Budyko假设的流域水热耦合平衡方法应用较为广泛;我国主要河川径流量除西北诸河和西南河流源区部分河流呈增加趋势外,其他区域河川径流大多呈减少趋势;人类活动是引起我国主要河川径流变化的主要原因。

“4·29”特别重大房屋倒塌事件舆情主题聚类及演化研究

研究房屋倒塌突发事件舆情主题及演化规律,可为应急主管部门引导和调控舆情提供实践指导。以长沙“4·29”特别重大房屋倒塌事件为对象,收集新浪微博平台上事件发生后8 d内的网民评论,运用词频逆文本频率(Term Frequency-Inverse Document Frequency,TF IDF)算法提取关键词,计算共现频率并刻画共现网络关系,耦合困惑度与K均值聚类(K Means)算法进行舆情主题聚类;采用对应分析方法,识别舆情主题的相关性,探究舆情主题随时间的热度变化趋势,揭示房屋倒塌事件舆情主题演化规律。结果表明:通过聚类得到的7个舆情主题依据相关性可耦合为救援善后T_(1)、调查追究T_(2)、安全防范T_(3)三大主题;以流言传播、官方召开发布会为最佳节点,将舆情传播划分为演化特征不同的前期、中期和后期。其中,前期主题T_(1)占优,中期主题T_(2)、T_(3)占优,后期主题T_(1)再次占优。通过类比分析化工爆炸事件舆情演化特征,验证了主题T_(1)、T_(2)、T_(3)对突发公共事件舆情演变起关键作用,满足公众对主题T_(1)、T_(2)和T_(3)的信息诉求是舆情平缓的关键。研究成果可为类似突发公共事件舆情治理提供参考。

光伏建筑研究文献计量学分析——基于2003-2023年WOS核心合集数据库

在建筑上安装光伏是建筑业降碳减碳最有效的途径,了解国内外光伏建筑的发展动态对我国部署光伏具有重大意义。对Web of Science中的核心合集数据库中5 275篇关于光伏建筑的文献进行计量研究分析。采用CiteSpace 6.2.2版本和战略咨询智能支持系统对相关文献进行了发文机构、发文量、国家地区、关键词共现、关键词突现、关键词聚类和关键词时间线图分析。研究发现,光伏建筑主要分为热效能、可再生能源管理和光伏发电系统三大研究领域,近些年的研究热点集中在光伏发电的能源管理问题和光伏发电量问题上。

冲击荷载下加卸载效应对冲击性岩石力学特性的影响

为研究矿井基本顶周期来压对冲击性矿柱动力学特性的影响,采用一维动静组合加载SHPB实验装置对循环加卸载预处理过的冲击性砂岩开展动态冲击实验,实验中预先设置3种不同的轴向循环阈值:6、12、18 MPa,然后进行不同冲击气压条件下的动态压缩实验。探讨了不同循环阈值和冲击气压下冲击性砂岩动态力学响应特性、能量演化规律及碎块分布特征。研究结果表明:岩样动态应力−应变曲线整体划分为弹性阶段、屈服阶段和破坏阶段。动态应力−应变曲线起始阶段近似直线,不存在静态单轴压缩中的裂隙压密阶段。平均动态抗压强度、平均动态弹性模量和平均动态变形模量随循环阈值增大先增大后减小;而平均动态峰值应变随循环阈值增大先减小后增大。临界阈值处岩样平均动态抗压强度、平均动态弹性模量和平均动态变形模量最大,平均动态峰值应变最小。反射能和耗散能密度随循环阈值增大先减小后增大;而透射能随循环阈值增大先增大后减小。临界阈值处岩样反射能和耗散能密度最小,透射能最大。冲击荷载下岩样呈4种破坏形态:粉碎破坏、岩块碎裂、岩块侧面剥落脱离、岩块劈裂。各冲击气压下岩样分形维数随循环阈值增大先减小后增大,随耗散能密度增加呈非线性增长。冲击性岩石致密性越好,冲击破坏时剧烈程度越弱,碎块块度越大,耗散能密度越小,分形维数越小。研究结果表明矿井基本顶周期来压小于冲击性矿柱损伤门槛值时,周期来压可提高岩层密实性,进而影响动态冲击时的破坏程度。

原油和烃源岩中三、四金刚烷类化合物的绝对定量与热演化研究

金刚烷类化合物独特的稳定性使其在评价高–过成熟油气的成熟度和来源等方面具有较大的应用前景。单、双金刚烷类化合物的易挥发性会影响其定量结果,而三、四金刚烷类化合物具有更强的稳定性,可以弥补单、双金刚烷类化合物的不足。三、四金刚烷类化合物在原油和烃源岩中的浓度普遍较低且缺乏绝对定量检测方法,极大地阻碍了三、四金刚烷类化合物的定量分析与应用研究。本研究通过人工高温熟化原油、柱层析除去芳烃类杂质干扰和气相制备色谱提纯等过程,得到了3种三金刚烷类化合物(三金刚烷、9-甲基三金刚烷和9,15-二甲基三金刚烷),建立了一套能够高效识别三、四金刚烷类化合物的气相色谱质谱–质谱(GC-MS-MS)绝对定量检测方法。原油和干酪根的黄金管封闭体系热模拟实验结果表明,三、四金刚烷类化合物产率分别在Easy Ro为3.1%、3.7%(原油)和3.1%、4.0%(干酪根)达到最大,而后开始裂解。根据金刚烷类化合物的裂解演化规律构建了2类三金刚烷类指标,有效拓宽了金刚烷类指标在指示成熟度方面的应用范围。

不同高度移动火源条件下隧道内无烟低温区域预测研究

为了得到隧道内不同高度移动火源火灾烟气的蔓延规律,采用FDS全尺寸数值模拟对隧道内移动火源火灾烟气蔓延全过程进行模拟,之后采用量纲分析的方法,分析无烟低温区域的长度与无量纲火源功率和无量纲火源移动速度之间的函数关系,对数值模拟所得数据进行处理并分析。研究结果表明:火源移动速度越快,低温无烟区长度越长,火源高度越高,低温无烟区的长度越短;低温无烟区长度与无量纲火源功率的1/3次方和无量纲火源移动速度呈非线性关系,并进一步建立隧道火灾无烟低温区长度的预测模型。研究结果可为发生火灾后人员的疏散路径规划、隧道通风系统的设计及优化提供理论支撑。

穿心电加热管道仿真和集输规律分析

随着外围油田深入开发,零散区块不断开采,穿心电加热技术得到了广泛应用。由于电线插入后管道内流体流动和传热的规律尚不明确,因此现场主要依靠保持电加热系统高功率运行来保证原油的安全输送,能耗浪费严重。针对穿心电加热管道的环空结构,基于质量、动量和能量守恒定律,分析电线插入管道后带来的摩擦和加热效应,建立了穿心电加热管道稳态温度和压力计算模型。结合智能算法校核摩阻和总传热系数,实现了不同功率下穿心电加热管道沿线水热力参数的准确计算;同时分析了含水率、输量、起点温度、功率和加热方式对电加热管道温度、压力、维温功率和维温能耗的影响情况。利用大庆油田电加热管道现场数据对模型进行了验证,结果显示:压力平均误差为7%,温度平均误差为4.16%,能够对生产起到指导作用,基本满足生产需要;此外,增大输量有助于节能降耗,全线维温是最节能的运行方式。

拉拔过程中全长灌浆锚固系统能量演化规律

锚固系统的拔出破坏实质上是能量驱动的失稳破坏,能量演化规律能充分反映锚固系统的承载性状和失效破坏过程。为了揭示循环荷载作用下全长灌浆锚固系统变形破坏过程中的能量转化机制及损伤劣化过程,文章基于热力学第一定律,给出了锚固系统在拉拔过程中的输入能、弹性能、耗散能、阻尼能以及损伤能等能量计算公式,并结合某项目全长灌浆锚索的现场拉拔试验,系统地研究了拉拔过程中全长灌浆锚固系统内部的能量演化规律。研究结果表明:1)随着循环次数和拉拔荷载的增加,输入能、弹性能、阻尼能以及损伤能均在逐渐增加,当拉拔荷载接近于极限抗拔力时,损伤能会呈现出急速增加的现象;2)在拉拔过程中,弹性能的变化幅度较小,其占比始终维持在50%左右;3)阻尼能和损伤能的演化是一个“此消彼长”的过程,阻尼能的占比曲线呈倒“U”型,其占比总体来说维持在20%以下,而损伤能的占比曲线大体呈“U”型,且其随着荷载比的变化幅度相对较为明显;4)全长灌浆锚固系统在拉拔过程中会产生较大的塑性损伤能,该过程实际上是不断损伤、刚度逐渐劣化的过程。本文成果对全长灌浆锚固系统的设计、施工、检验及监测预警具有一定借鉴意义。

西鞍山铁矿深部立井围岩稳定性数值模拟分析

针对西鞍山铁矿辅助井开挖诱致井筒围岩变形破坏问题,以700~1000m深度范围辅助井掘进为依托,运用FLAC3D有限差分模拟软件对竖井开挖过程进行了三维数值分析,阐明了不同深度辅助井开挖诱致井筒围岩变形破坏演化特征,揭示了辅助井掘进过程井筒掘进工作面支护效应下围岩应力及位移释放规律,分析获得了辅助井掘进诱致井筒围岩弹性应变能积聚、迁移与释放演化机理。研究表明:在辅助井开挖过程中,井筒围岩塑性区破坏方式以剪切破坏为主,塑性区范围随着竖井掘进深部的增加不断增加,且最大主应力峰值位置位于井筒围岩弹、塑性区交界处;井筒围岩径向位移随深度呈线性增加,最大径向位移值为90.64 mm,且最小水平主应力方向围岩位移大于最大水平主应力方向;随着竖井掘进深度增加,井筒掘进工作面以上距其2m位置井筒围岩应力释放率达到95%,且井筒围岩径向位移随距井筒掘进工作面距离增加呈非线性增加,并在距井筒掘进工作面24m处径向位移达到最大;受开挖扰动影响,井筒围岩弹性应变能密度呈非线性增加,并根据岩爆判据预测竖井掘进至1050m处井筒围岩存在岩爆发生可能性。

基于专利计量的金华市清洁能源产业创新研究

文章基于专利计量方法,结合社会网络分析和可视化分析揭示金华市清洁能源产业创新发展态势。结果表明:产业领域专利申请整体呈指数增长趋势;水能是专利申请量最多的领域,太阳能、氢能和生物质能技术领域具备较高的关注度和技术研发热度;企业是产业发展的主要推动者,大专院校和科研单位专利产出能力较低,高价值专利培育不足;专利合作网络规模较小,但活跃创新主体区域分布集中,技术聚集度较高,部分主体间已形成较为稳定的合作关系;产业技术融合趋势日益明显,各个子领域之间的交叉与合作呈现出增长态势。因此,建议优化产业技术布局,提升高价值专利培育能力,拓展合作网络,提升产业竞争力。

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