不同位置空气间隔装药爆破减振和破碎效果试验

为探究空气间隔装药爆破技术中最优的空气间隔位置,在金堆城南露天矿爆破施工中,分别选取药包上部、中部、底部3种不同空气间隔位置进行爆破试验。利用TC-4850动态测振仪对爆破振动进行监测,通过Split-Desktop 3.0软件对爆破块度进行统计分析,结果表明:药包中部间隔装药爆破的减振和破碎效果优于上部和底部位置。并采用ANSYS/LS-DYNA对三种不同空气间隔位置的爆破进行数值模拟,模拟结果与现场试验结果相符。     

轴向不耦合装药结构形式优化仿真研究

为了改变某隧道平导爆破效果差、爆炸能量利用率低的现状,采用ANSYS/LS-DYNA模拟不同轴向不耦合装药结构形式对爆破效果的影响,优化装药结构,以期达到增强爆破效果,降低粉尘量和岩石大块率的目的。合理的选择数值模拟中的材料模型和算法,是高效模拟分析轴向不耦合装药结构爆破的关键,因此采用ALE算法对孔口空气填塞不耦合,孔口炮泥填塞、上部空气间隔不耦合,孔口水介质填塞、底部水介质间隔不耦合,孔口炮泥填塞、上部水介质间隔不耦合,孔口水介质填塞、中部水介质间隔不耦合和孔口炮泥填塞与中、上部水介质间隔不耦合的装药结构进行数值模拟,并以爆炸应力波云图和最大拉应力来评价炸药爆破效果。数值模拟结果表明:水介质可以降低炮孔壁附近岩石的压力。装药长度1.25m时,孔口炮泥填塞、上部空气间隔不耦合装药结构较孔口空气填塞不耦合装药结构,能提高爆炸能量的利用率;孔口水介质填塞、底部水介质间隔不耦合装药结构和孔口炮泥填塞、上部水介质间隔不耦合装药结构,爆炸能量利用率基本相同;孔口水介质填塞、中部水介质间隔不耦合装药结构的炸药爆炸能量利用率较其余5种装药结构都大,能提高爆炸应力波对岩石的作用,使得爆炸应力波更加均匀作用于岩体,降低大块率产生。此数值模拟结果可为现场爆破方案设计与实施提供依据。     

轴向不耦合装药结构形式优化仿真研究

为了改变某隧道平导爆破效果差、爆炸能量利用率低的现状,采用ANSYS/LS-DYNA模拟不同轴向不耦合装药结构形式对爆破效果的影响,优化装药结构,以期达到增强爆破效果,降低粉尘量和岩石大块率的目的。合理的选择数值模拟中的材料模型和算法,是高效模拟分析轴向不耦合装药结构爆破的关键,因此采用ALE算法对孔口空气填塞不耦合,孔口炮泥填塞、上部空气间隔不耦合,孔口水介质填塞、底部水介质间隔不耦合,孔口炮泥填塞、上部水介质间隔不耦合,孔口水介质填塞、中部水介质间隔不耦合和孔口炮泥填塞与中、上部水介质间隔不耦合的装药结构进行数值模拟,并以爆炸应力波云图和最大拉应力来评价炸药爆破效果。数值模拟结果表明:水介质可以降低炮孔壁附近岩石的压力。装药长度1.25m时,孔口炮泥填塞、上部空气间隔不耦合装药结构较孔口空气填塞不耦合装药结构,能提高爆炸能量的利用率;孔口水介质填塞、底部水介质间隔不耦合装药结构和孔口炮泥填塞、上部水介质间隔不耦合装药结构,爆炸能量利用率基本相同;孔口水介质填塞、中部水介质间隔不耦合装药结构的炸药爆炸能量利用率较其余5种装药结构都大,能提高爆炸应力波对岩石的作用,使得爆炸应力波更加均匀作用于岩体,降低大块率产生。此数值模拟结果可为现场爆破方案设计与实施提供依据。     

空气间隔器在深孔台阶爆破中的应用

叙述了空气间隔器在孔内不同间隔位置对爆破效果的影响,并对相应的爆破机理进行了详细的解释。根据矿山爆破实际,采取了孔口间隔、中间间隔和底部间隔3种不同的空气间隔。顶部使用空气间隔能有效地防止冲孔,但是对减少大块、爆破根底效果不明显;中部使用空气间隔可以有效解决爆破块度问题,但爆破根底仍有残留,同时需另外下发起爆药包,增加了工人的劳动强度。采用底部空气间隔时,在间隔长度H<(14～20)r时,可以减小粉碎区,增大裂隙区,从而有利于克服根底爆破残留。     

地铁区间隧道不同装药结构光面爆破应用研究

为了提高光面爆破效果,以青岛地铁为工程背景,进行了周边孔不同装药结构的光面爆破试验研究.理论分析了连续装药和间隔装药2种装药结构爆破对孔壁的压力情况,从切缝药包爆破裂纹的成缝机理上,解释了切缝药包定向断裂控制爆破技术改善光面爆破效果的原因.通过现场应用得出:当进尺为1 m且岩性较好时,采用连续装药结构,岩性较差时,采用切缝药包连续装药结构;当进尺在1～2m且岩性较好时,采用轴向空气间隔装药结构,岩性较差时,采用切缝药包轴向空气间隔装药.施工中取得了理想的爆破效果,施工经验被青岛其它2条地铁线及相关隧道所吸纳.     

中部空气间隔不同比例装药对炮孔孔壁受力及碎石块度的影响

为分析装药中部不同空气间隔位置对炮孔孔壁受力的影响，以Starfield迭加法为基础，得出中部空气间隔装药爆破时整段孔壁上的冲击压力计算公式。在ANSYS-DYNA中建立多组不同中部空气间隔位置的计算模型，对孔壁及周围岩体的受力和损伤度进行分析。最后，进行现场爆破实验，使用WipFrag软件对碎石块度分布的变化规律进行分析。结果表明：中部空气间隔装药爆破时，孔壁压力整体呈现两端大、中间小的分布特征，装药段孔壁受到的冲击压力达到最大，冲击波以8字型向炮孔周围传播。当空气间隔位置在装药段中点时，上、下段药柱周围岩体受力大致相等，碎石块度相对均匀。因此，垂直台阶进行露天爆破开采时，为降低大块和粉料的产生率，空气柱上、下段可进行等比例装药，倾斜边坡可以适当向上调整空气间隔位置。     

某露天采场深孔台阶爆破空气间隔装药的应用

为了改善某露天采场爆破作业中存在的振动大、大块率高等问题,采用中部空气间隔装药法代替连续装药法并对空气间隔比例进行对比研究。基于ANSYS/LS-DYNA有限元软件构建装药不变条件下空气间隔比例分别为10%、12.5%、15%、17.5%和20%的中部空气间隔方案计算模型进行模拟分析:装药量不变条件下空气层比例为17.5%时,炮孔中、底部有效应力分布均匀,没有出现应力过度集中现象,效果最佳。经过现场试验后证明:采用空气层比例17.5%的中部空气间隔装药爆破后,大块率下降了27.26%、振动降低5%~12%,有效降节约了经济成本。     

节理裂隙岩体空气间隔装药爆破试验研究

为探索节理裂隙岩体空气间隔装药爆破技术的可行性,在贵州某土石方工程爆破施工现场选取岩体节理裂隙发育和岩体相对完整的2种地质区域,分别选取空气层的比例为5%、10%、15%、20%、25%、30%等工况进行混装铵油炸药孔口与孔底空气间隔装药爆破试验,利用Split—Desktop 3.0软件对爆破块度和爆破开挖后根底进行统计分析,得出了不同区域相同空气层位置、比例以及相同区域不同空气层位置、比例下的爆破效果。结果表明:节理裂隙发育区域采用空气间隔装药容易产生根底;岩体完整性对空气间隔装药参数取值有显著影响;岩体节理裂隙发育区域,应当选用较小的空气间隔比例;该试验区域的节理岩体可采用间隔比例为10%～15%的孔口空气间隔装药进行爆破。     

高温钢筋混凝土基础爆破拆除

采用控制爆破拆除高炉基础,针对基础的高温(80-100℃)特点,采取了强制降温、药包隔热等技术措施。通过进行药包耐热模拟试验,确定装药、填塞、连线作业的允许时间。通过合理的施工组织,减少药包在炮孔内的时间,确保了爆破安全。对于厚大基础的爆破拆除,采用较大的孔网参数及空气间隔装药技术,取得了很好的爆破效果。     

水封爆破装药结构优化数值分析及其应用

以温泉隧道为研究背景,从应力、振速变化、动态损伤以及爆后粉尘的角度对药柱上部水间隔、两端水间隔和下部水间隔三种装药结构进行模拟分析,选取最优结构用于工程施工。研究结果表明:(1)药柱底部水间隔装药结构易造成孔口围岩破碎导致爆炸气体流出,降低爆破效果;药柱上部和两端水间隔装药结构爆炸应力持续时间较长,有利于围岩破碎,其中药柱两端水间隔装药结构底部存在水介质,对孔底围岩起到保护作用;(2)采用两端水间隔装药结构能够同时降低炮孔两端围岩振速和所受应力,减少炸药能量流失,使其充分作用于围岩进行破碎,降低炸药单耗;(3)药柱上部水间隔装药结构对孔口围岩损伤最小,导致爆破后岩石块度较大;药柱底部水间隔装药结构形成的整个损伤区域最小,采用这种装药结构炸药单耗偏高;药柱两端水间隔装药结构形成的损伤区域规整,爆破后岩石块度最小;(4)三种装药结构中,下部水间隔结构爆后粉尘浓度最高,两端水间隔装药结构爆破后粉尘浓度稍高于上部水间隔装药结构,但是相差不大,而两端水间隔装药结构的爆破效果要优于上部水间隔装药。综上所述,药柱两端水间隔装药结构最优,可用于工程施工。综上所述,药柱两端水间隔装药结构最优,可用于工程施工。     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

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.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.