钢筋混凝土排架的控爆拆除

本文研究了爆破拆除钢筋混凝土建筑物时建筑结构的失稳条件,对钢筋混凝土排架的控制爆破拆除进行了设计计算,并分析了拆除爆破效果和拆除爆破对钢筋混凝土基础的影响。     

钢筋混凝土水塔爆破预拆除方案的设计方法

钢筋混凝土水塔爆破拆除前,预拆除的安全稳定分析和最优预拆除方案的合理设计是爆破拆除水塔的关键.针对目前钢筋混凝土结构水塔预拆除理论存在的不足,文章通过计算最小和最大保留面积,提出了进行预拆除方案的设计步骤、方法和相应的稳定性演算公式.同时,探讨了爆破预拆除保留面积的优化问题.解决了爆破前预拆除的安全稳定与起爆后的顺利倒塌之间的矛盾.通过实例证明完全可以指导实践.     

拆除爆破工程安全管理的特点与对应措施

总结了拆除爆破工程安全管理的特点,指出爆破拆除工程的安全管理应有风险意识,给出了爆破拆除项目风险管理的方法,提出了爆破拆除工程实施过程中应注意的安全问题.     

不同基坑支撑拆除方式对比研究

目前基坑支撑拆除主要采用机械拆除和爆破拆除2种方式,以上海地区2个大型基坑支撑拆除为背景,通过采用振动监测仪监测施工所产生的振动、走访调查施工所产生的噪音对周边居民的影响、实际记录施工工期等方法,对比分析了不同拆除方式的振动危害、噪音危害、工期、飞石危害、经济成本、施工安全性,从而多角度总结了基坑支撑机械拆除与爆破拆除...     

层次分析法在拆除爆破影响因素分析中的应用

介绍了层次分析法的基本原理及其在拆除爆破效果影响因素分析中的作用,并用此原理,建立了影响拆除爆破因素的层次结构模型。通过计算各因素对拆除效果影响的程度权值,找出了影响拆除爆破的主要因素,为拆除爆破工程设计与爆破效果分析提供参考。     

层次分析法在拆除爆破影响因素分析中的应用

介绍了层次分析法的基本原理及其在拆除爆破效果影响因素分析中的作用,并用此原理,建立了影响拆除爆破因素的层次结构模型。通过计算各因素对拆除效果影响的程度权值,找出了影响拆除爆破的主要因素,为拆除爆破工程设计与爆破效果分析提供参考。     

危险品工房(设备)销爆拆除分步操作方法探讨

文章分析了危险品工房（设备）销爆拆除时存在的安全问题,阐述了销爆拆除过程中,隔离、清扫、冲洗、燃烧处理、化学处理、设备拆除、时效处理等重要环节的拆除步骤和注意事项,探讨了一种安全、高效、彻底、环保的完整拆除方法。     

110m烟囱及皮带走廊控制爆破拆除

根据待拆除烟囱、皮带走廊的结构特点、拆除要求及其周围的施工环境条件,制定了两座烟囱单独定向爆破拆除,而煤仓和皮带走廊采用毫秒延时起爆技术同时爆破拆除的设计方案;同时进行了爆破参数、爆破网路等的合理设计和精心施工,加强安全防护,拆除爆破达到了预期效果。     

复杂环境条件下热风炉的爆破拆除

热风炉的结构比较特殊,加之环境复杂,所以采用爆破方法拆除时难度较大.介绍了对热风炉的爆破拆除方法.实践证明,爆破非常成功.这种爆破拆除方法打破了传统的拆除方法,对以后的类似工程具有指导意义.     

电厂大型厂房大解体式爆破拆除

焦作电厂老厂主厂房结构复杂,相邻构筑物多,拆除工期紧.决定采用大解体控制爆破拆除技术进行拆除.主体拆除前,先对一些结构进行了预拆除.采用非电加强双向多回路网格式爆破网路,一次起爆了1.5万个药包和686 kg炸药,成功地爆破拆除了3万多m2主厂房.爆破后解体充分,爆破震动小,爆堆高度1～3 m,为后期的清运提供了良好的条件.     

Early fatigue crack growth as the damage accumulation process

A probabilistic approach to modeling of the initial stage of fatigue crack growth is suggested based on the concepts of continuum damage mechanics. The material is presented as a set of microstructural elements with randomly distributed properties. Both the grains and intergranular boundaries are considered as the elements of microstructure. The parameters of resistance of each element to damage accumulation are considered as random variables. These parameters are distributed among the elements independently that allows to model the damage process in polycrystalline materials. The damage measure depends on the characteristic normal and tangential stresses in order to take into account the tensile and shear fracture modes for each element of microstructure. It is assumed that a nucleus of a crack is initially present near the body surface as a single completely ruptured element. The final damage of an element is considered as the crack advancement. The crack is modelled as a sequence of ruptured grains for the transgranular fracture, and as a sequence of couples of neighboring ruptured grains when the intergranular rupture is considered. Numerical simulation is performed to illustrate feasibility of the proposed model. In particular, non-planar crack propagation, blunting, kinking and branching of cracks at the early stage is demonstrated. The non-monotonous pattern of the short crack growth process is observed. Statistical scattering of the current crack size and the crack growth rate as functions of the cycle number and the crack depth is studied.     

A Grid as Smart as the Internet

A new era of electricity is dawning that combines the decarbonization of the grid with the extensive electrification of all sectors of society. A grid as smart as the internet is needed to harness the full potential of renewables, accommodate technology disruptions, embrace the rise of prosumers, and seamlessly integrate nano-, mini-, and micro-grids. The internet is built upon a layered architecture that facilitates technology innovations, and its intelligence is distributed throughout a hierarchy of networks. Fundamental differences between data flows and power flows are examined. The current operating paradigm of the grid is based on the conviction that a centralized grid operator is necessary to maintain instantaneous power balance on the grid. A new distributed paradigm can be realized by distributing this responsibility to sub-grids and requiring each sub-grid to maintain its net power balance. A grid as smart as the internet based on this new paradigm, as well as a hierarchical network structure and a layered architecture of operating principles, is presented.     

旋转机械升降速过程的双谱-FHMM识别方法

结合双谱和因子Markov模型，提出了一种基于双谱的特征提取建立机组各状态相应的因子隐Markov模型状态识别法，并成功地应用到旋转机械升降速过程的故障诊断中，同时还与基于双谱的特征提取的HMM状态识别法进行了比较，实验结果表明该方法是有效的。     

Inflation waves in non-linear distensible tubes

A mathematical model for large amplitude wave propagation in a thin walled distensible tube is developed. The tube wall is considered as a membranic shell made of an incompressible, non-linear viscoelastic material with cylindrical orthotropy. The fluid is regarded as incompressible and inviscid and the flow is quasi-one-dimensional. The case of a pressure step applied at one end of a uniform straight tube is solved as an example. The system of partial differential equations, describing the motions of the fluid and the wall, are integrated numerically by using a two-step explicit scheme. Flow and deformation variables as well as the wave velocity are determined in time and space.     

Synthesis of Hydrogen‐Substituted Graphyne Film for Lithium–Sulfur Battery Applications

Graphyne (GY) is a new type of carbon allotrope, which is viewed as a rapidly rising star in the carbon family referred to as 2D carbon allotropes due to its extraordinary properties. Considering the dynamic nature of the alkyne metathesis reaction, a hydrogen‐substituted graphyne (HsGY) film is successfully synthesized on a gas/liquid interface using 1,3,5‐tripynylbenzene (TPB) as the precursor. The synthesized HsGY film is used as a sulfur host matrix to be applied in lithium–sulfur batteries (LSBs). The HsGY@S electrode is prepared using S₈ as sulfur source and presents excellent electrochemical performance.     

疏水缔合两亲聚合物凝胶的形成规律及性能

基于疏水缔合两亲聚合物具有良好的耐温抗盐性能,研究了以其为主剂的新型凝胶体系.利用黏度法筛选出体系的最优配方:两亲聚合物主剂的相对分子质量为750×10<'4>、浓度1000mg/L,交联剂乌洛托品、间苯二酚、助剂柠檬酸的最佳用量分别为0.3%、0.02%、O.3%(质量分数,下同),且最佳体系的储能模量G'大于损耗模...     

浅谈符号图形的发展及其在平面设计中的运用

符号最终目的不是单纯的作为一种记号 ,而是通过表现记号达到理解交流其中的内容。符号的最大特征就是从个别当中提取出具有普遍性的东西 ,它作为人类共通的语言超越了国度、种族与历史 ,使人们互相理解。它可以作为一种独立的视觉语言在平面设计中运用     

Middle-field formulation for the computation of wave-drift loads

New formulations of second-order wave loads contributed by a first-order wave field are developed by applying two variants of Stokes’s theorem and Gauss’s theorem to a formulation consisting of direct pressure integrations on a body’s hull which is called the near-field formulation. In addition to this direct formulation and the formulation derived from the momentum theorem called the far-field formulation, for the computation of drift (surge/sway) forces in horizontal directions and drift (yaw) moment around the vertical axis, one of new formulations is defined on the control surfaces surrounding the body and called the middle-field formulation. After a brief summary of both pressure-integration (near-field) and momentum (far-field) formulations, the development of the middle-field formulation involving control surfaces is described and complemented in detail in the appendices. The application of the new formulation shows that the near-field and far-field formulations are mathematically equivalent for wall-sided, as well as non-wall-sided bodies and under the condition that the mean yaw moments are expressed with respect to a space-fixed reference point. It is shown that the middle-field formulation is as robust as the far-field formulation and as general as the near-field formulation of second-order loads on a single body as well as on multiple bodies. Furthermore, the extension to the computation of a second-order oscillatory load, which is so far accessed only by the near-field formulation, is envisioned.     

Numerical analysis of spontaneously condensing phenomena in nozzle of steam-jet vacuum pump

The primary fluid in a steam-jet vacuum pump is not assumed as a perfect gas as general research in the present study. A mathematic model based on the wet steam model for transonic flow is proposed to investigate the flow behaviours of primary fluid in the nozzle of a steam-jet vacuum pump. The simulation based on a wet steam model was carried out to predict the flow characteristics of primary fluid along the nozzle axis by a commercial computational fluid dynamics (CFD) code (FLUENT6.3). The simulation results showed that there was spontaneous condensation as the supersonic flow passing through the nozzle and the simulation results had a good agreement with the experimental data. It is found from the numerical simulation results that the steam flow characteristics in nozzle are quite different from a wet steam model and a perfect gas assumption: the outlet pressure of the nozzle predicted in the present study is higher than that as the primary fluid assumed as perfect gas, the outlet velocity is about 10% lower than that as the primary fluid assumed as a perfect gas, and the temperature at the outlet of the nozzle is much higher than that as the primary fluid assumed as a perfect gas. The simulation results demonstrate that the thermo-positive process due to steam condensation would hinder the supersonic expanding flow process in nozzle and depress the efficiency of the nozzle which would affect the pumping performance of steam-jet pump.     

一种运动估计算法的性能评估方法

同时考虑算法的精度和效率,以常用的基于梯度的运动估计算法为例,提出了一种运动估计算法的性能评估方法.在该方法中,以表征算法精度的偏差为横坐标,以表征算法效率的执行时间为纵坐标,构建了一个偏差一时间二维性能评估坐标系,通过设置算法的不同参数,绘制偏差一时间性能评估曲线.性能评估实例表明了所提出的偏差-时间性能评估方法在评估基于梯度的运动估计算法性能时的有效性.