环切杆状发射装药的点传火试验研究

针对环切杆状发射药装药,设计了两种点传火方案进行试验验证:方案1#是中心传火管;方案2#是在中心传火管上端增加一个点火药包,以便加强弹丸底部装药的点火。通过100 mm火炮弹道试验负压差的分析,两种点传火方案均能满足点传火技术要求,方案2#负压差较方案1#负压差小,射击安全性提高。对点火延迟时间的分析发现,点火延迟时间越短,起始燃气生成速率越高,越易生成较大的压力波。     

震源药柱用低爆速炸药的研制

文章根据地震勘探震源药柱对低爆速炸药的要求 ,确定炸药的组分、配方及其混药工艺 ,产品经 2 3m井下传爆试验表明 ,该炸药爆速满足 16 0 0 m· s-1～ 2 30 0 m· s-1的要求 ,起爆和传爆性能可靠     

对塑料导爆管标准修改的建议

针对即将修订的塑料导爆管标准 WJ2 0 19- 91,对其中爆速和抗拉强度两项指标进行了讨论。建议规定导爆管的平均爆速必须在 16 0 0 m· s-1～ 2 0 0 0 m· s-1之间 ,且同时将导爆管按爆速大小分为高爆速、中爆速和低爆速三种类别 ,其平均爆速分别为≥ 190 0 m· s-1、170 0 m· s-1～190 0 m· s-1、16 0 0 m· s-1～ 170 0 m· s-1;并规定同一批导爆管爆速极差不大于 10 0 m· s-1。抗拉强度分成高强度、中强度和普通强度三类 ,其抗拉强度分别为≥ 180 .0 N、12 0 .0 N～ 180 .0 N、6 8.6N～ 12 0 .0 N。     

活性炭净化废水处理研究

通过动态实验优选出粒状活性炭水处理工艺 ,设计出适合于家庭和饮食摊、店餐具洗涤废水处理的净化装置“净化节水器” ,并进行了试运行。实验表明 ,洗餐具净化水处理单元操作的最佳工艺参数为 :混凝剂投加量30mg·L- 1 ,反应池流速 0 .0 3m·s- 1 ,消毒剂用量 2 5mg·L- 1 ～ 30mg·L- 1 。“净化节水器”初步使用效果良好 ,为水资源重复利用和消毒灭菌提供了途径     

国际单位制中具有专用名称的导出单位

计量类别单位名称符号同基本单位的关系频率赫兹 Hz s~-1力牛顿 N m·kg·s~-z压力帕斯卡 Pa m~-1·kg·s_~2能功,热量焦耳 J m~2·kg·S~-2功率,辐射通量瓦特 W m~2·kg·s-2电量,电荷库仑 C s·A电位,电位差,电动势伏特 V m~2·kg·s~-3·A~-1电容法拉 F m~-2·kg~-1·s~4·A~2     

锆金属粉尘云最小点火能和最低着火 温度的试验研究

为研究锆金属粉尘云燃烧的基础特性参数,从而为其安全性能提供依据,采用哈特曼管试验系统和最低着火温度测定系统分别对锆金属粉尘云的最小点火能（MIE）和最低着火温度（MIT）开展试验研究。分别研究了锆金属粉尘云质量浓度、点火延迟时间和喷粉压力对MIE的影响,以及粉尘云质量浓度对MIT的影响。结果得出:中位径为33.49 μm的锆金属粉尘云的MIE在1~3 mJ之间;在50~500 g/m³质量浓度范围下,随着质量浓度增大,MIE先减小后增大,在质量浓度为400 g/m³时达到最小;点火延迟时间从10 ms增至180 ms,MIE先减小后增大,在60 ms时达到最小;喷粉压力从0.4 MPa增至1.0 MPa,MIE先减小后增大,在0.6~0.8 MPa间达到最小。该粒度锆金属粉尘云的MIT为210 ℃左右,在一定浓度范围下,MIT随粉尘浓度的增加而减小。     

硼系高能点火药对太安燃烧转爆轰的影响

文章研究了硼系高能点火药对PETN燃烧转爆轰的影响.试验证明高能点火药剂BKF1在有外界加强约束的条件下,能够使装药压力小于13.8 MPa的PETN完全燃烧转爆轰;对改性后的BKF2进行PETN燃烧转爆轰试验,在相同条件下,BKF2使PETN燃烧转爆轰的概率远远大于BKF1 .     

快淬速度对(Nd,Pr)10.5(FeCoZr)83.5B6显微结构和磁性能的影响

采用部分过快淬加后续晶化退火处理工艺,研究了快淬速度对低稀土含量双相复合(Nd,Pr)10.5(FeCoZr)83.5B6合金显微结构和粘结磁体磁性能的影响.合金快淬转轮线速度为24,26,28和30 m·s-1,退火温度655～715℃,退火时间5～20min.快淬速度直接影响条带的显微结构和磁体磁性能.以26m·s-1速度快淬出的条带,快淬态由非晶和微晶混合组成,在700℃经10min晶化处理,可获得平均晶粒尺寸约30nm的均匀、细小显微组织,磁性能也最佳.用3.25wt%环氧树脂粘结的磁体磁性能为Br=0.703T,Hci=544 kA·m-1,Hcb=351 kA·m-1,(BH)m=70 KJ·m-3.     

聚萘醌电流变液体的性能研究

以聚萘醌为分散相 ,对溴二苯甲烷和二甲基硅油为分散介质 ,聚硅氧烷侧链高分子液晶为添加剂 ,配制成电流变液体 (ER液体 ) ,应用德国RV2 0电流变仪测试性能 ,研究其ER效应 ,以求获得高性能的ER液体。结果表明 ,该ER液体有很强的ER效应。 77℃ ,电场强度 (E)由 0增至DC2 0 0 0V/nm ,剪切速率为 30 0s- 1时 ,剪切应力由 30Pa增至 90 0 0Pa ,表观粘度由 4 0mPa·s增至 30 0 0 0mPa·s ;剪切速率为 5 0 0s- 1时 ,剪切应力由 30Pa增至 15 0 0 0Pa ,表观粘度由 4 0mPa·s增至2 35 0 0mPa·s。 4 4℃ ,同样条件下 ,剪切速率为 6 0s- 1时 ,剪切应力由 2Pa增至 2 4 0 0 0Pa ,表观粘度由 4 5mPa·s增至 2 2 0 0 0mPa·s     

不同宽度及放置角度下聚甲基丙烯酸甲酯的燃烧传热特性

研究了宽度分别为2 cm、3 cm、5 cm和8 cm的聚甲基丙烯酸甲酯(PMMA)在放置角度为0°、15°、30°和45°的情况下燃烧传热特性。通过图像分析、红外热像、热电偶测温等技术对火焰形态及燃烧特性参数(火蔓延速度、火焰倾角、火焰高度以及火焰温度等)进行了表征。研究发现,有机玻璃燃烧过程中,热解前锋呈现出U型的特点,宽度越大,其U型演变时间越长。放置角度越大时,火蔓延速度对宽度的敏感性越大,即宽度越大火蔓延速度越大。这主要由于,随着宽度和放置角度的增加,火焰倾角变得越来越小,火焰与材料表面更加贴近,从而促进热量的传递。研究同样发现,在相同放置角度下,平均火蔓延速度受平均火焰高度以及上下波动程度的影响;火焰温度基本上不受宽度影响等特点。     

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.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

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.……     

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.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.