桥礅柱定向倒塌拆除爆破后坐分析

根据建筑物拆除爆破失稳原理，对桥礅柱定向倒塌控制爆破拆除试爆时产生后坐进行力学分析，得出试爆产生后坐的主要原因是保留支撑截面瞬间强度不够，调整主爆相关参数，使主爆达到预期效果。     

桥洞拆除试爆失败原因分析

文章针对桥洞控爆试爆中出现的问题，从炮眼深度、堵塞质量、装药量和装药密度等方面分析了试爆失败的原因，并给出了调整后的钻爆参数。     

城市复杂环境下90 m钢筋砼烟囱的定向爆破拆除

拟拆除90 m钢筋混凝土烟囱位于宝鸡市区,周边环境复杂,采用单向倒塌控制爆破拆除。分析并确定了烟囱爆破切口的形状、尺寸、爆破参数、起爆网路和爆破安全技术。为了减少炸药用量和减小爆破振动危害,对爆破切口进行预处理。在烟囱倒塌轴线两侧的待爆左右板块中部预先对称开凿1.2~1.5 m宽的缺口,并将烟囱出灰口的门框拆除,割断门框的钢筋,形成宽2.4 m的窗口。复式簇联网路的应用有效提高了网路的准爆性,保证了爆破工作的可靠性。采用开挖减振沟、设置缓冲土垫层等措施降低爆破振动。爆破效果表明,确定的相关参数与安全措施合理有效,保证了邻近建筑物及设施的安全。     

控制爆破在拆除铁路桥梁中的应用

文章针对铁路桥梁试爆中出现的问题,从炮孔深度、炮孔排距、装药量、起爆顺序等方面进行了分析,并给出了调整后的钻爆参数及爆破效果。     

同济医院老门诊楼控爆拆除设计与施工

详细介绍了同济医院老门诊楼控爆拆除的方案选择，爆破参数，起爆网络的设计，以及装药前的试爆，飞石飞散状况观测及飞石对防护材料的破坏性实验，为安全防范飞石危害和降低成本提供有力的依据，爆一结合现场勘测和倒塌过程摄像，对爆破的效果进行了分析和讨论。     

两座60m砖烟囱定向爆破拆除及结果分析

临沧市两座60m砖烟囱的爆破拆除因多方面原因采用了两种方案,这两种方案除切口位置不同外,其余爆破参数保持一致:一号烟囱爆破切口布于底部+0.7 m,向北偏西51°倾倒,对支撑部位的出灰口砖砌封堵;二号烟囱爆破切口布于底部+1.5m,避开了底部烟道口、出灰口对烟囱定向倾倒的影响.两座烟囱的爆破效果大相径庭,一号烟囱因出灰口的影响偏离设计方向约30°,二号烟囱则按设计方向倾倒.通过对比两座烟囱的倒塌,分析烟囱发生偏移的原因,确定砖烟囱较合适的切口圆心角范围,强调爆破前预处理工作的重要性,并为以后类似的工程实例提供参考.     

地下水封洞库施工巷道开挖爆破技术研究

以国内某地下水封洞库的建设为例对施工巷道的开挖爆破技术进行了研究。首先,基于施工巷道的地质构造特征提出了合理的加固和支护建议。其次,在巷道口近区开挖阶段,对全断面爆破和台阶爆破的效果进行了对比分析;在巷道主体的开挖阶段,对人工钻爆和机械钻爆两种爆破方案的爆破效果效率进行了统计与对比分析。最后,对爆破作用下施工巷道的沉降变形进行了监测分析。研究结果表明：施工巷道口近区经预加固后,全断面爆破与台阶爆破均能满足设计和规范要求,但全断面爆破的施工速率更高;进入巷道主体后采用全断面爆破;人工钻爆与机械钻爆各有优劣势,人工钻爆的施工效率更高,机械钻爆的安全性更高。开挖爆破诱发的位移和沉降均满足设计和相关规范的要求。     

复杂环境下大型不规则框架结构厂房爆破拆除

为确保复杂环境下大型不规则框架结构厂房爆破拆除顺利实施,采用了分区、分排、多层延时爆破。根据"回"字型结构特点,划分四个区域,多层布置切口;针对不同的立柱类型,选择合理的爆破参数;同时进行了爆前预处理、试爆及防护。爆破达到了预期目标,保证了周边设施的安全及其它机组正常不间断地运行,爆破振动速度在安全范围内,厂房解体充分,爆堆最大高度12m。     

小浪底进水口工程钻爆

本文结合小浪底进水口一期开挖工程实际钻爆施工实践，总结出适合该工程特点的钻爆参数，有效地指导了施工。     

控制爆破在拆除铁路桥梁中的应用

文章针对铁路桥试爆中出现的问题,从炮孔深度、炮孔排距,装药量,起爆顺序等方面进行了分析,并给出了调整后的钻爆参数及爆破效果。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.