国家标准馆馆藏最新国外标准

1.ISO 535-2014纸和纸板.水吸收性的测定.Cobb法2.ISO 1813-2014皮带传动.包括宽截面带及六角带的多楔带、有接头三角皮带、三角皮带.抗静电带的导电性:特性和试验方法3.ISO 2351-3-2014螺钉和螺母用装配工具.机动旋具头.第3部分:六角凹头螺钉用螺丝刀4.ISO 2476-2014顺丁橡胶(BR).溶液聚合型.评定规程5.ISO 3925-2014非密封放射性物质.鉴别和证书     

Butterfly线性阵列音箱系统

Butterfly蝶式线阵列音箱系统是专为户外演出而设计的,包括C.D.H.483全频音箱、C.D.L.1815超低频音箱、V.I.P.设计软件及运输系统和配套的附件。C.D.H.483全频音箱是三分频二通道的设计,高频部     

2007年到期的中国名牌产品目录

1.大米2.小麦粉3.糖(白糖、精果、果冻) 4.派类食品5.低温肉制品6.农用塑料大棚膜7.果汁类饮料8.黄酒9.皮衣10.t车1 1.液体洗涤剂1 2.笔(铅笔、自来水笔、回珠笔、记号笔) 1 3.炊具(电饭锅、压力锅、不粘锅) 14.家用燃气灶具15.真丝绸面料16.针织品(内衣袜子) 17.裤子1日.羊绒大衣19.黄金首饰20.乒乓球运动器材21.保险柜/箱22.程控文换机23‘铿离子充电电池24.大中型客车25.汽车玻璃26.铝合金车轮27.全钢子午线轮胎28.实木复合地板29.文联聚乙烯电力电缆30.钢丝绳31.磁性材料32.铝合金建筑型材33硬质合金34.高纯阴极铜35.人造金刚石36.税控…     

应用微量元素进行酒类的内涵防伪

人体是由多种元素构成.其中微量元素占人体总重量的0.005%.微量元素包括七十种元素.其中有14种是人体必须的微量元素.包括有铁、锌、碘,铜、氟.虽然这些微量元素的含量各不相同.在人体内极少.却与人体生命活动息息相关并是不可缺少的元素.它们参与人体的多种机体代谢活动,除促进人体生命活动的微量元素外.在微量元素里还存在一小都分对人体有害的微量元素.它们分别是铅.汞.锻.铋.锑、镉这些微量元素会损害人体神经.     

国家标准馆馆藏最新国外标准

1.ISO 124-2014胶乳,橡胶.固态物质总含量的测定2.ISO 1096-2014胶合板.分类3.ISO 2403-2014纺织品.棉纤维.马克隆尼值的测定4.ISO 2795-2014滑动轴承.烧结轴套.尺寸和公差5.ISO 10245-2-2014起重机.限定及指示设备.第2部分:移动式起重机6.ISO 12505-1-2014造口术辅助器用皮肤屏障.试验方法.第1部分:尺寸,表面p H值和吸水性     

国家标准馆馆藏最新国外标准

1.ISO 128-24-2014技术制图.表示法的通用原则.第24部分:机械工程制图线2.ISO 834-10-2014耐火试验.建筑构件.第10部分:确定对结构钢构件应用防火材料贡献率的专门要求3.ISO 2322-2014丁苯胶(SBR).乳液和溶液聚合型.评估规程4.ISO 2393-2014橡胶试验混合料.制备,混合和硫化.设备和规程5.ISO 2929-2014油槽车排吸油用橡胶软管和软管组     

WC-Co(Ni,Fe)硬质合金比磁饱和的标记、单位和换算

在推证了铁磁材料的饱和磁化强度MS或饱和磁极化强度JS和磁饱和状态下的磁感应强度BS间的定量关系的基础上,得到了WC-Co(Ni,Fe)硬质合金的MS,BS和JS分别与合金密度ρ的比值即标称比磁饱和(通称"磁饱和")间的数值换算关系为:BS/ρ(T.m3.kg-1)=JS/ρ(T.m3.kg-1)=μ0.MS/ρ(A.m2.kg-1)=μ0σ(A.m2.kg-1),JS/ρ(4π×10-7T.m3.kg-1)=σ(4π×10-7T.m3.kg-1)=MS/ρ(A.m2.kg-1)=σ(A.m2.kg-1),BS/ρ(×10-7T.m3.kg-1)=4πσ(×10-7T.m3.kg-1)=4π.MS/ρ(A.m2.kg-1)=4πσ(A.m2.kg-1)。因此,采用σ(A.m2.kg-1,4π×10-7T.m3.kg-1)和4πσ(×10-7T.m3.kg-1,A.m2.kg-1)作为比磁饱和的标记和单位并恪守上述各磁学量的换算关系,能确保其中σ的绝对值与单位质量合金的磁矩值一致,并能对比磁饱和数值进行有效的评估和对比。     

耐候钢排水管案例

钢材强度高,有延展性.价格也便宜.这使它成为一种很重要的材料.不幸的是.在潮湿的空气中.普通钢材易生锈并且会不断地生锈。在钢材中加入不少于12%的铬后.它就再不生锈.但其价格更加昂贵.多年后美国钢铁业发现.在普碳钢中加入少于10%的铜和少量磷.就可以使钢材生锈的速度减半,他们把这     

国家标准馆馆藏最新国外标准

1.ISO 289-1-2014未硫化橡胶.用剪切圆盘型粘度计测定.第1部分:穆尼粘度的测定2.ISO 834-11-2014防火试验.房屋建筑构件.第11部分:结构钢构件防火评估的具体要求3.ISO 3691-5-2014工业车辆.安全性要求和鉴定.第5部分:步进卡车4.ISO 5721-2-2014农用拖拉机.操作者视野用要求、试验规程和验收准则.第2部分:侧面和后方视野     

数列极限的若干计算法

计算数列极限有着多种多样的方法,除了要熟练运用极限的四则运算法则,极限和无穷小量之间的关系和初等函数的连续性以外,还要掌握和运用较多的方法和技巧.其主要方法有:1.四则运算法.2.利用重要极限求数列极限.3.单调有界数列法.4.利用定积分求数列极限.     

Schädigungsverhalten metallischer Hülsen in CFK‐Bolzenverbindungen

The excellent specific and mechanical properties of fibre reinforced plastics (FRP), especially in respect of substituting of primary metal structures, caused an increasing demand in the aircraft construction industry. The material requirements demanded from conventional rivet connections, for example the lockbolt system, increased contemporaneously. Unfortunately, rivet holes of the mating parts interfere with the natural fibre patterns and thereby causing certain imperfections in the material. In addition, the fitting of the lockbolt could lead to undesirable delamination and fibre disruptions around the corner of the rivet hole. This has a further adverse impact on the joint strength. The insertion of a steel sleeve leads to a radial expansion of the sleeve during the fitting of the lockbolt. Thus, critical shear stress can be avoided during the bolt fitting. The increased complexity of the whole joint structure requires compliance with strict process limits, otherwise damages to the sleeve and, consequentially, to the entire compound are likely. The aim of this study is a detailed characterization of the sleeve material and of the entire process including the process limits. The finite element method is used as an important tool for assisting in the select correct process parameters. Based on the results of tensile tests, a certain material model on the basis of one failure criterion was defined for the steel sleeve and then implemented in the simulation of the bolt fitting. Within the setting of an unfavourable combination of process parameter, the numerical results evidence a realistic failure of the sleeve when compared with results from experimental tests.     

Formation of the reaction zone between tin‐copper brazing fillers and aluminum‐silicon‐magnesium alloys: Experiments and thermodynamic analysis

A primary challenge in brazing is the controlled formation of phases resulting from interactions of elements of the liquid filler metal with those of the base material. The morphology of the brazed joint, which is decisive for the mechanical properties of the joint, is influenced by present elements and process parameters such as brazing temperature and time. Furthermore, the wetting of the base material is a crucial factor in joining of aluminum because of the low wettability of the alumina layer by molten brazing filler metals. In order to remove the alumina and prevent reoxidation of the substrate surface, the brazing process can be conducted in vacuum or inert gas atmosphere. Again, selection of process parameters is crucial for the quality of the brazed seam. In this work, we focus on the influence of the process parameters on the wetting behavior and the formation of aluminum‐copper phases theoretically by means of thermodynamic calculations using a CALPHAD database as well as by means of in‐situ observations in the large‐chamber scanning electron microscope (LC‐SEM) and by brazing experiments. Both the critical temperatures with respect to the wetting and the reaction kinetics as well as the crucial stages of the brazing process and the resulting phases were determined.     

空心微珠填充聚氨酯泡沫塑料的力学性能

对不同密度和不同填充质量比的空心玻璃微珠填充聚氨酯泡沫塑料进行拉、压实验,研究了微珠对复合泡沫塑料力学性能的影响。实验结果表明:复合泡沫塑料拉伸曲线特征与普通泡沫塑料类似,但具有不同于普通泡沫塑料的压缩应力-应变特性;材料密度越大,微珠对胞体壁的增强效果越好;微珠团聚和界面粘结不良将可能导致材料力学性能的下降。根据有限元模拟结果和试件破坏形貌的观察探讨了材料的变形和破坏机制。      

Specific Features of the Behavior of Ceramics Based on ZrO2 with an Admixture of 9 Mole% CeO2 in the Process of Deformation

For zirconia ceramics stabilized with 9 mol.% CeO ₂, we study specific features of the processes of deformation and formation of the zones of transformation of the tetragonal phase into the monoclinic phase under the action of mechanical stresses. It is shown that, at room temperature, this transition occurs explosively (autocatalytically) and is accompanied by the formation of large zones of the -phase in the form of strips on the surface of tension of the specimen and the appearance of a nonlinear sawtooth section in the stress–strain diagram. As the testing temperature increases, the degree of autocatalyticity decreases together with the degree of nonlinearity and the diagrams lose their sawtooth character. At the same time, the strength of the material becomes almost four times higher at ~ 200°C and then decreases to the initial level at 400°C. It is assumed that this Type of mechanical behavior can be explained by changes in the mechanisms of hardening of ceramics.     

On fracture initiation toughness and crack sharpness for Mode II cracks

Fracture toughness of brittle materials is calibrated in experiments where a sample with a preexisting crack is loaded up to a critical point of the onset of static instability. Experiments with ceramics, for example, exhibit a pronounced dependence of the toughness on the sharpness of the crack/notch: the sharper is the crack the lower is the toughness. These experimental results are not entirely compatible with the original Griffith theory of brittle fracture and Linear Elastic Fracture Mechanics which both ignore the crack sharpness.To explain the experimental observations qualitatively we earlier considered Mode I cracks [Volokh KY, Trapper P. Fracture toughness from the standpoint of softening hyperelasticity. J Mech Phys Solids 2008;56:2459-72.] and in the present work we extend our considerations to Mode II cracks. We simulate pure shear of a thin plate with a small crack of a finite and varying sharpness. In simulations we introduce the failure energy as a limiter for the stored energy of the Hookean solid. The energy limiter induces softening, indicating material failure. Thus, elasticity with softening allows capturing the critical point of the onset of static instability of the cracked plate, which corresponds to the onset of the failure propagation at the tip of the crack. In numerical simulations we find that the magnitude of the fracture toughness can not be determined uniquely because it depends on the sharpness of the crack: the sharper is the crack the lower is the toughness.Based on the obtained results we argue that a stable magnitude of the toughness of brittle materials can only be reached when a characteristic size of the crack tip is comparable with a characteristic length of the material microstructure, e.g. grain size, atomic distance etc. In other words, the toughness can be calibrated only under conditions where the hypothesis of length-independent continuum fails.     

An experimental and numerical study of the dynamic behaviour of a counter-flow evaporator

The dynamic behaviour of a counter-flow, water-heated evaporator is studied experimentally and numerically. The frequency distribution of the random oscillations of the mixture-vapour transition point and the superheat temperature at the exit of the evaporator is obtained for steady operation of the system. These oscillations are well correlated. The transition point movement is found to cause fluctuations in the refrigerant temperature over 1 m downstream of its range of motion. Step changes in the refrigerant flow rate and the heating water flow rate demonstrate the non-linear characteristics of the evaporator where the time constants for step increases and step decreases of the same magnitude differ significantly. The distributed model predicts the variation of the superheat temperature and the evaporator pressure following step changes in the inputs with good accuracy.     

An estimate of the errors of a detector of micrometeoroid and technogenic particles

The characteristics of the methods and instruments for recording high-speed particles, which determine the main errors of measurements, based on a solution of the equation of the kinetics of a shock plasma and the theory of shock waves and the equivalent circuits of the ionization and capacitor converters of the parameters of the particles are considered. Calculations of the random errors of the integral method of recording the parameters of the particles are presented. The most reliable estimate of the parameters of the particles is obtained, taking into account the noise properties of the ionization-type converter. __________ Translated from Izmeritel’naya Tekhnika, No. 12, pp. 58–62, December 2005.     

Fundamental mechanisms and their interactions in shear‐clinching technology and investigation of the process robustness

The compliance with increasingly stricter emission standards is a challenge for the automotive industry, which requires the utilization of lightweight materials e. g. aluminium and high‐strength steels. Hereby, the load‐optimized design of body parts and the reduction of wall thicknesses are enabled. But, due to the use of dissimilar materials, common joining technologies are reaching their limits. On the one hand, joining by welding is often not possible because of different melting temperatures. On the other hand, joining by forming with additional fasteners increases the cycle time and the costs. However, joining by forming without fasteners is often limited by the mechanical properties of the joining partners. The innovative shear‐clinching technology combines shear‐cutting and clinching in a single stage process and thereby enables joining by forming of materials with high differences regarding their mechanical properties. However, by the combination of the sub‐processes cutting and joining, the complexity of the technology is increased. Thus, within the scope of this work, the fundamental mechanisms in shear‐clinching and their interactions as well as the robustness of the process are analysed, in order to promote the applicability of the technology.     

Discussion of the feasibility of the Einstein refrigeration cycle

A careful modelling of the thermodynamic properties of the water–ammonia–butane system, the working fluid mixture used in the Einstein cycle, with the Patel–Teja cubic equation of state is performed. Numerical simulation is used to investigate the feasibility limits of this refrigeration cycle. Two modified configurations of the cycle are considered. A conflict between the evaporator and the condenser/absorber operating conditions is noted. The condenser/absorber operation needs a higher system pressure, which limits the refrigeration temperature in the case of air-cooling. On the other hand, the condensation of ammonia and the presence of a small quantity of water in the evaporator limit also the refrigeration temperature. In the case of a water-cooled machine, with a condenser/absorber temperature of 30 °C, the cycle COP reaches 0.19 which is still low.     

EURAXLES – A global approach for design,production and maintenance of railway axles: WP1 – Advances in fatigue load analysis and reliability assessment of railway axles

The work presented in this paper was led within the collaborative project “Euraxles” of the FP7 program of the European Commission. It aimed at developing processes and methods that contribute to the minimization of the risk of fatigue failure of railway axles in service. This paper focuses on the development of a method to assess the reliability of axles according to fatigue damage. The proposed approach is mainly based on the stress strength interference analysis (SSIA) and the fatigue‐equivalent‐load (FEL) methods. It aims at calculating the axles’ probability of fatigue failure, by characterizing the variability of real in‐service loads and the scatter of the axles fatigue strength, and at evaluating more accurately the actual design margins. First of all, the main lines of the stress strength interference analysis method are recalled. This method aims at evaluating the in‐service reliability of components for their design or their homologation. It is used in many industries for various applications (mechanical components or systems, electronic elements, etc.). In the second part, the fatigue load analysis method that is proposed for railway axles is described. It starts with a post‐processing of an axle load measurement: from a time signal of forces applied to both wheels fitted on the axle, fatigue cycles of bending moment applied to the axle are identified and transformed into a cyclic equivalent load, the M_eq, which is a measurement of the severity of the initial variable load. Then, virtual but realistic load spectra are generated, thanks to a classification operation followed by a random draw of elementary load data that considers the operation and maintenance conditions of the axle. All the spectra are then analysed thanks to the fatigue‐equivalent‐load method in order to build the distribution of in‐service load severities that gives a picture of the stress to which the axles are submitted. In the third and last part of the paper, the methods are applied to real data of “Société nationale des chemins de fer français” (SNCF), the French national railway operator. Sensitivity analyses are performed in order to quantify the effect on the M_eq of variations of parameters and to verify the convergence and robustness of the process. Finally, results obtained for a passenger coach are given. The comparison between the distribution of load severities and the normative load, defined as according to european standards EN13103, shows that, for the studied axle, the normative load is very conservative. Using the axles fatigue limits identified on full‐scale tests, a stress strength interference analysis is performed to calculate the probability of failure of the axle.