卫生陶瓷成型开裂缺陷的研究

介绍了卫生陶瓷在成型工序中开裂缺陷的特征，产生原因以及克服的方法．并指出保持泥浆的稳定性和规范的操作方法是克服开裂缺陷的关键。     

Application of bridging-law concepts to short-fibre composites Part 3: Bridging law derivation from experimental crack profiles

This is the third paper in a series of four where notch sensitivity, fracture energy and bridging laws are studied in short-fibre polymer composites. Here, bridging laws are derived from experimental crack-opening profiles in centre-hole notched tensile specimens. The materials studied are three types of commercial glass–mat composites with different reinforcement structures and matrices. The materials have softening bridging laws and the calculated fracture energies from bridging laws are in good agreement with values determined directly by experiment. The calculated maximum local bridging stress is found to be higher than the uniaxial tensile strength. An outline of a failure criterion for notched specimens based on the crack-bridging approach is presented.     

Pore pressure development in hybrid fibre-reinforced high strength concrete at elevated temperatures

The present experimental work investigates the build-up of pore pressure at different depths of High Strength Concrete (HSC) and Hybrid-Fibre-Reinforced High Strength Concrete (HFRHSC) when exposed to different heating rates. First, the effect of the measurement technique on maximum pore pressures measured was evaluated. The pressure measurement technique which utilised a sintered metal and silicon oil was found to be the most effective technique for pore pressure measurement. Pore pressure measurements carried out showed that addition of polypropylene fibres is very effective in mitigation of spalling and build-up of pore pressure inside heated HSC. Addition of steel fibres plays some role in pore pressure reduction at relatively higher pressures in deeper regions of concrete during fast heating. Pore pressure development is highly influenced by the rate of heating with fast heating leading to higher pore pressures in the deeper regions of concrete compared to slow heating.     

表面活性剂对微细涤纶纤维的吸附研究

分别采用亚甲基蓝两相滴定法和表面比电阻法研究了表面活性剂在微细涤纶纤维表面的吸咐。研究发现：阴离子表面活性剂在微细纤维上的等温吸附线基本符合Brunauer的第四种类型；阴离子表面活性剂对纤维表面的吸附能力与结构有很大关系；表面比电阻法证明了在微细涤纶纤维上确实发生了表面活性剂的吸咐，从而使得纤维表面电荷增加，使表面电阻相对下降。     

清梳联合机工艺技术与设备创新探讨

通过利用AFis纤维检验仪对清梳联各单机在制品的测试结果 ,得出了清梳联工程中棉结、杂质的变化规律 ,并对清梳联工程中清棉打手的组合结构、清梳除杂分配、清梳联短绒控制、生条定量控制、排尘、滤尘与空调系统等重要问题进行了讨论。     

Design and development of long-period grating sensors for temperature monitoring

Long Period Gratings (LPGs) have been developed using carbon dioxide laser in a standard optical fibre. LPGs with a periodicity of 600 μm and grating length of 24 mm have been inscribed on standard single mode fibre. Such gratings have been used in designing temperature sensors and temperature is monitored up to 80°C. The sensitivity of such type of sensor is 0·06 nm/°C where as for standard Fibre Bragg Grating (FBG) it is 0·011 nm/°C. The LPG performance is also evaluated after γ-ray irradiation for total dose of 5 KGy and has not shown any effect on transmission spectrum.     

MODELLING THE TENSILE FRACTURE BEHAVIOUR OF THE REINFORCING FIBRE YARNS IN CERAMIC MATRIX COMPOSITES

Abstract— Using experimentally determined data on fibre radius distributions, yarn geometry, matrix and fibre elastic moduli and frictional shear stress at the matrix/fibre interface (obtained by nano-indentation experiments), the failure probability of the composite fibre yarns (after matrix cracking) is estimated. Each fibre is divided into a fixed number of segments above and below the matrix crack. The failure probability on every segment of each fibre is computed using Weibull fibre strength statistics. A fibre is assumed to be broken when the cumulative failure probability for the complete yarn reaches a value of 0.5. The segment and fibre are then selected at "random", according to their individual failure probabilities. After fibre failure, the broken fibre can only carry the frictional load and the load drop is transferred to its neighbours according to their distances to the broken fibre. The remote stress is then modified to match again the cumulative failure probability of 0.5 and a new fibre is broken. This procedure is repeated until all the fibres are broken. In this way, it is possible to obtain the "characteristic" load carried by the yarn and its corresponding elongation. Fibre extraction and pull-out behaviour are also considered. The roles of different load-transfer laws (from global to highly localised) are examined. The model is applied to simulate the fracture tensile behaviour of individual yarns of SiC/SiC ceramic-matrix composites. The results are compared with those obtained from tensile experiments on SiC/SiC individual yarns. The computed fracture morphology, in terms of individual pull-out lengths, is also compared to the actual SEM fractography of a woven SiC/SiC composite.     

Initial deployment of fibre in the local network for narrowband use in Spain: Technology,engineering and cost

This paper covers: (1) the field trials, with fibre in the local network systems, being conducted in Spain and intended for delivery telephone-based services to residential customers; (2) the technical and functional requirements of these types of system intended for commercial (regular) deployment to be started around late 1993/early 1994, and (3) the most relevant initial deployment scenarios and persubscriber investment aspects. The field trials are located in Madrid and in Barcelona: their rationale, technical characteristics and the lessons learned so far are described. Such trials are providing insight into what requirements and objectives are anticipated to be needed should such new technology be an actual alternative to copper-based subscriber loops. The requirement for such fibre in the local network systems intended for regular deployment in the near term are indicated, including technical and functional requirements of the optical line terminals (OLTs) (at local exchanges) and optical network units (ONUs) (located near customer premises); transmission requirements and optical distribution network (ODN) requirements and design aspects. For starting regular deployment, three preferred scenarios are identified. The chief parameters affecting persubscriber investments are illustrated including the number of fibres per ONU, and the number of users being served from each ONU. It is shown that in order to achieve cost parity with copper loop (which requires an initial investment of between $600 and $800) a capacity of some 60 narrowband (64 kb/s) channels per ONU should be required.     

Radiation-hardness studies of high OH content quartz fibres irradiated with 500 MeV electrons

We investigated the darkening of nine high OH⁻ fibre types irradiated with 500 MeV electrons from the Linac Injector of LEP (LIL) at CERN. The transmission of Xe light was measured in situ in the 350–800 nm range. The induced attenuation at 450 nm is typically 1.52±0.15 dB/m for a 100 Mrad absorbed dose. Two-parameter fits for darkening and recovery are presented. After irradiation the tensile strength remains essentially unchanged. For Polymicro quartz core fibres the tensile strength is typically 4.6±0.4 GPa.