复杂环境下62m高烟囱的拆除爆破及安全控制

为了拆除周边环境复杂的62m高砖混结构烟囱,采用了定向爆破技术。针对烟囱直径尺寸大、厚度宽、结构强度高的结构力学特点以及周边环境特点,预先开凿大尺寸导向窗,适当减少了爆破面积;通过设计合理的钻孔和爆破切口,确定炸药单耗和起爆方式;采用减振以及安全技术措施,确保了烟囱爆破拆除顺利实施。尤其针对个别炮孔中炸药单耗大的情况,为控制产生的飞石以及落地碰撞产生个别飞散物,在爆破位置采取三层柔质覆盖材料直接或间接进行近体防护。爆破取得了预期效果,可为类似爆破工程提供参考。     

复杂环境下62m高烟囱的拆除爆破及安全控制

为了拆除周边环境复杂的62m高砖混结构烟囱,采用了定向爆破技术。针对烟囱直径尺寸大、厚度宽、结构强度高的结构力学特点以及周边环境特点,预先开凿大尺寸导向窗,适当减少了爆破面积;通过设计合理的钻孔和爆破切口,确定炸药单耗和起爆方式;采用减振以及安全技术措施,确保了烟囱爆破拆除顺利实施。尤其针对个别炮孔中炸药单耗大的情况,为控制产生的飞石以及落地碰撞产生个别飞散物,在爆破位置采取三层柔质覆盖材料直接或间接进行近体防护。爆破取得了预期效果,可为类似爆破工程提供参考。     

180m高钢筋混凝土烟囱三段单向控制爆破拆除

对复杂环境下180m高钢筋混凝土烟囱,采用三段单向分次控制爆破拆除。采用复式梯形爆破切口,确保烟囱倒塌方向;铺设黄土缓冲垫层和个体特殊防护措施,有效地控制烟囱倒塌触地振动;采用刚性和柔性复合式措施防控爆破飞石;采用高空吊篮法进行高空爆破切口施工。爆破后,烟囱倒塌方向准确,周边建筑物和设施安然无恙,取得了良好的爆破效果,达到了安全、精细和快速爆破拆除的目的,为以后类似爆破工程提供参考。     

180m高钢筋混凝土烟囱三段单向控制爆破拆除

对复杂环境下180m高钢筋混凝土烟囱,采用三段单向分次控制爆破拆除。采用复式梯形爆破切口,确保烟囱倒塌方向;铺设黄土缓冲垫层和个体特殊防护措施,有效地控制烟囱倒塌触地振动;采用刚性和柔性复合式措施防控爆破飞石;采用高空吊篮法进行高空爆破切口施工。爆破后,烟囱倒塌方向准确,周边建筑物和设施安然无恙,取得了良好的爆破效果,达到了安全、精细和快速爆破拆除的目的,为以后类似爆破工程提供参考。     

180m高钢筋混凝土烟囱爆破拆除

介绍了在复杂环境中,采用控制爆破技术爆破拆除180 m钢筋混凝土烟囱的工程实例,论述了工程方案的确定,参数设计及主要安全措施.针对烟囱尺寸大、钢筋密、混凝土强度高的结构特点,预先开凿大尺寸导向窗减少了爆破面积.特别针对烟囱高度特别高,自重大的特点,针对性进行防护土堤的设计.通过多角度观察,确认防护土堤有效地控制了爆破次...     

210m钢筋混凝土烟囱高位缺口控制爆破拆除实践

结合一座210 m高钢筋混凝土烟囱控制爆破拆除工程,介绍了烟囱高位缺口爆破的参数设计和安全措施。受倒塌场地条件的限制,设计利用100 m高度位置的检修平台处作为高位爆破缺口进行分段分次爆破拆除;由于爆破缺口位置较高,设计采用了利于准确定向的倒梯形缺口,并对缺口参数和爆破参数进行了优化选取;为了保证缺口爆破和整体倒塌效果,对内衬和背部钢筋等进行了预处理施工;同时针对高缺口爆破飞石较远、上段倒塌触地震动较大等爆破危害采取了覆盖防护、控减震沟和铺缓冲层等有效防护措施。爆破倒塌过程对下段烟囱形成了撕裂破坏,但整体爆破效果良好。     

突变截面高烟囱分段爆破拆除及振动控制

为了达到安全拆除180m钢筋混凝土烟囱的目的,根据烟囱截面尺寸变化差异大、周围环境复杂和倒塌空间不足的特点,结合复杂环境下突变截面高烟囱分段爆破拆除工程实例,采用两次高位切口单向控制爆破拆除技术,上部切口采用倒梯形爆破切口,下部切口采用正梯形爆破切口。通过精心设计、施工,实现了烟囱准确定向并有效控制了烟囱的后坐。根据理论计算公式校核了爆破振动和塌落触地振动速度以及爆破飞石距离。采取铺设缓冲垫层、开挖减振沟等措施减小振动,并通过分析爆破振动监测数据,证实了这些措施对振动控制的有效性和实用性,可为同类工程提供参考。     

分段控制爆破技术在210m烟囱拆除中的应用

根据国家相关政策,某电厂现有一座高210 m烟囱需要进行爆破拆除。介绍了分段控制爆破技术在实际工程中的具体应用。通过在烟囱100 m处和底部开设倒梯形爆破切口、梅花形布孔,确保烟囱倒塌方向;爆破采用毫秒延时起爆、在烟囱倒塌方向开挖减震沟、烟囱触地地面铺设松软黄土缓冲层、倒塌方向三面搭设防护屏障等措施有效地控制了爆破振动和飞石危害,达到了比较理想的效果。     

突变截面高烟囱分段爆破拆除及振动控制

为了达到安全拆除180m钢筋混凝土烟囱的目的,根据烟囱截面尺寸变化差异大、周围环境复杂和倒塌空间不足的特点,结合复杂环境下突变截面高烟囱分段爆破拆除工程实例,采用两次高位切口单向控制爆破拆除技术,上部切口采用倒梯形爆破切口,下部切口采用正梯形爆破切口。通过精心设计、施工,实现了烟囱准确定向并有效控制了烟囱的后坐。根据理论计算公式校核了爆破振动和塌落触地振动速度以及爆破飞石距离。采取铺设缓冲垫层、开挖减振沟等措施减小振动,并通过分析爆破振动监测数据,证实了这些措施对振动控制的有效性和实用性,可为同类工程提供参考。     

复杂环境下150m砼烟囱两段单向控制爆破技术

介绍了在周围环境不能满足烟囱整体定向倾倒的复杂条件下,采用两段单向控制爆破技术对150m高钢筋混凝土烟囱实施拆除。通过开设定向窗、减荷槽,采用倒梯形爆破切口,选择合理的爆破参数及精细化施工等确保了烟囱倒塌方向准确,有效地控制了烟囱后坐。通过铺设缓冲垫层、搭设防护屏障、开挖减振沟等措施有效控制了爆破触地振动及飞石等危害,达到了设计效果,可为类似爆破工程提供参考。     

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.