关于密封垫片压缩回复性能名词术语的探讨

密封垫片的压缩回复性是一项十分重要的性能.目前国内对＂回复＂和＂回弹＂两个概念没有很好地区别,以致普遍采用＂回弹率＂这一术语.讨论了＂回弹率＂和＂回复率＂的区别,并建议采用＂回复率＂或＂复原率＂替代＂回弹率＂.     

A novel representation of tandem systems with inter-stage storage applied to on-line system monitoring

One of the goals of operating a tandem manufacturing system with finite inter-stage storage and asynchronous operations is to meet the demand without over-producing, under-producing or carrying large quantities of material in storage. We believe that analysing the operation of such a system on a real-time basis helps achieve this goal. The first step in this real-time analysis would be to quantitatively associate the causes and effects of over-production or under-production as they occur. This requires determining the cumulative effect that the performance that any stage has on the system, based on its history, the current system state and the interrelationships between the stages. This paper proposes a method which first represents uniquely and completely each stage and surrounding storage as an element. While this system, which consists only of this simple type of element functions in exactly the same way as the original one, each element is put into an ideal world for decoupled measurement. Though an element behaves in exactly the same way whether it is in the ideal world or in the real world, the elapsed times in the two worlds since the beginning of production can be different, since the responses (occurrences and durations of the blockings and starvations) of the two worlds can be different. A phase parameter is introduced for each element to represent this difference. Once the formation of the phase parameter of the output element is formulated, quantitative relationships between causes and effects of over-producing or under-producing can be explained as they occur.     

再论先进制造技术及其发展趋势

此文是《先进制造技术及其发展趋势》的深化与补充。首先,指出制造业在国家发展中所占的战略地位。接着,从三个方面十二点详细地分析了先进制造技术发展的特色与趋势:产品本身,“精”、“极”、“文”;制造过程,“绿”、“快”、“省”、“效”;制造方法,“数”、“自”、“集”、“网”、“智”,并强调上述这些方面均应基于“制造”与“机械”这两个基点之上。最后,提出了先进制造技术发展的指导思想与我国应该优先发展的方向,强调必须自主创新,必须“以人为本”。     

Single-Electron Characteristics of a ФЭУ-184U Photomultiplier Tube

Single-electron and time characteristics of a -184U photomultiplier tube with a uviol window are presented. The -184U single-electron resolution can reach a value of 63–64%, and, in case of single-electron light-striking of the photocathode, the photoelectron transit time distribution (full width at half maximum) is 6 ns.     

从e-商务到e-工厂的NW/IT变革 e-时代的10年发展

从1993年美国国防部DARPANet、能源部BITNet、国家自然科学基金会NFSNet搭桥并网,1994年解密为商用internet,到装上欧洲19国CERN开发的WWW,开展全球e-m、e-a、e-3b业务,形成“信息高速公路”上的“新经济”和“知识经济”。这“e-时代”10年发展的趋势是:“e-商务”经由e-efg落实到“透明工厂”,再发展到“e-工厂”,应证了马克思的经典论点“工具的革新是生产力中最重要的”,美国人的现代观点“硅谷是美国的工艺心脏”。     

Automated Devices for the Testing of Mill Rolls

Multichannel -type devices developed at TsNIITMASh for the automated ultrasonic inspection of cylindrical objects, such as mill rolls, shafts of turbines and compressor units, circular welded joints of thick-walled shell rings, etc., are described. These devices feature from two to eight acoustoelectronic channels. Acoustic contact occurs through industrial water. The testing is performed under workshop conditions; the object being inspected is rotated by a turning lathe or any other handling mechanism. Sonication is simultaneously performed by piezoelectric transducers (PETs) with input angles of 0, 40, 50, 60, and 70° and also by surface and head waves in order to reveal surface and subsurface flaws. A wide-span eddy-current transducer of special design is also used for this purpose. All data are stored in flash memory and retrieved on a PC located in an office. The inspection results are displayed as C- and B-type scanning defectograms. Moreover, it is possible to obtain an isometric image of flaw zones. -type devices have been used for over one and a half years in two workshops at OAO Severstal'.     

“本地连接”常见故障的成因及解决方法

在网络连接配置和使用中,"本地连接"是很常见的一种故障.文内从"本地连接"受限、"本地连接"丢失和"本地连接"冗余这三种常见故障入手,详细分析了它们的成因、排除的思路及解决的方法.     

Molecular dynamics simulation of polyethylene under cyclic loading: Effect of loading condition and chain length

Two nano-blocks of polyethylene (PE) are made and subjected to cyclic deformation with various loading conditions, i.e., strain vs. stress control, zero lateral strain vs. zero lateral stress, and different load amplitude by using the coarse grained molecular dynamics simulation. The one block is filled with 1000 random coil chains of [-CH₂-]³⁰⁰ (long chain), while the other 10 000 chains of [-CH₂-]³⁰ (short chain). The random coil chains are freely grown and relaxed in a simulation box of , then compressed to and relaxed to obtain a stress-free equilibrium. Under the zero lateral stress condition, σ^′=0, the long-chain block shows a leaf-like hysteresis curve both in the stress- and strain-controlled cyclic loading. The area of the hysteresis loop increases as the maximum load is changed to , and , respectively. The “Mullin's effect” is also observed, i.e., the stress-strain curve depicts lower path in the 2nd or later loading, although the target is never a rubber with filler. Under the zero lateral strain condition, ε^′=0, the long-chain block shows little hysteresis with the stress amplitude of 100 MPa, while it shows rapid or unstable elongation around at ε=0.35 in the simulation of ε_max=0.5 and . The short-chain block also shows unstable elongation under the ε^′=0 condition even with the stress amplitude of 100 MPa, noting that it has an upper yield point of at ε=0.35 and lower one around at ε=1.6. On the other hand, the short-chain block is stretched without remarkable stress increase up to the strain around 1.0, under the lateral condition of σ^′=0. Then the block shows “strain hardening” and comes up to the external stress of 100 MPa. It is worth noting that the block shows a leaf-like hysteresis in the 2nd or later cycle; the stress goes back to zero around ε=1.0 in the unloading process and rises up immediately when the load is reversed, as same as the long-chain block.     

磁控溅射制备Cr7C3多层复合镀层及其耐磨性能

Using closed field unbalanced magnetron sputtering ion plating technique, Cr₇C₃ multilayer graded composite coatings was preparated by adjusting sputtering process parameters. The microstructure of the coatings was analyzed by a X-ray diffraction. Surface and cross-sectional morphologies were observed by the transmission electron microscopy. Adhesion, hardness, and friction and wear behaviors were tested. Wear scars was observed by the optical microscope. Results indicate that the Cr₇C₃ coatings microstructrue is amorphous phase structrue, mainly consists of primary Cr₇C₃ particles, a small amount of Cr₃C₂ and others particles, and is fine, dense and uniform. The coatings has good adhesion and high hardness, good payload carrying capacity and life reliability, excellent friction coefficient and wear resistance performance, and the sliding dry friction coefficient is stabilized in the range 0.15~0.10, the wear rate is about 2.26×10^-16 m³/(N·m) in air.     

Portable Electromagnetic-Acoustic Thickness Meters (EMAT)

Two varieties of contactless electromagnetic-acoustic portable thickness meters with autonomous power supply, created on the basis of up-to-date digital technologies, are described. The instruments implement a new highly efficient design of magnetic field concentrator developed on the basis of new magnetic materials. The -- thickness meter is equipped with a powerful microprocessor-based data processing system, which expands the capabilities of the instrument. The -100 thickness meter is a small-size and small-weight instrument. The main advantage of both instruments is that they can be operated on corroded untreated surfaces without the use of a contact fluid. Both instruments are suitable for testing through coatings of considerable thickness (up to 2 mm) and can be operated under workshop and field conditions.     

Error Corrections in a Sampling Sliding Along a Pulse Envelope Based on Decoding Tables

Code combinations of 2 ⁿ symbols +1 and –1 suggested for identification of characteristic features leading edge, trailing edge, maximum, minimum, horizontal portion, start of leading edge, end of leading edge, start of trailing edge, and end of trailing edge in a binary-code envelope of a pulse measured by an eddy-current transducer (ECT) scanning a tested surface generate a group code. This group code ensures for four levels of noise immunity the maximal likelihood in identification of reference sequences distorted by noise. The structure of a product code, which is also generated by the reference fragments, results in a higher capability of correcting for errors in moving samplings of signal envelopes, in particular, it reduces the degree of uncertainty in identification of the most important features of ECT pulses. The paper suggests simple decoding algorithms and regular logical structures that provide a high efficiency of the procedure eliminating errors in binary sequences of coded envelopes.     

Measurement of Sub-Nanometer Lubricant Films Using Ultra-Thin Film Interferometry

The ultra-thin film interferometric method of measuring the thickness of very thin films in lubricated contacts has been refined so as to be able to measure films down to 0.3nm with a standard deviation of 0.15nm. The main remaining source of measurement variation for films below 3nm thick is the surface roughness of the contacting solids. This modified technique has been applied to study the film-forming properties of three fluids, hexadecane, a dilute solution of surfactant in hexadecane, and cyclohexane. Purified hexadecane shows a very slightly enhanced oil-film thickness below 1nm. The long-chain surfactant forms a boundary film 2nm thick. Cyclohexane behaves as though it forms a surface layer about 1nm thick with viscosity three times the bulk fluid viscosity.