胶带运输系统安全性的模糊综合评判

安全性评价是提高企业安全管理水平的重要措施之一,结合平顶山煤业(集团)有限责任公司一矿的生产实际,建立了安全性评价指标体系.应用模糊数学理论,对胶带运输系统的安全性进行了模糊综合评判,指出了影响运输安全的主要因素中存在的问题,并提出了相应的改进措施.     

Rapid analysis of tetracaine for a tape stripping pharmacokinetic study using short‐end capillary electrophoresis

A rapid and simple short‐end (reverse) capillary zone electrophoresis method was developed and validated for the separation and quantification of tetracaine in skin using tape samples. The separation was performed in a 485 mm (400 mm to window) × 50 µm internal diameter fused silica capillary using a background electrolyte of phosphoric acid–Tris pH2.5 at –25 kV. The extraction of tetracaine from tape samples was achieved using methanol diluted to 50% with water before injection. Procaine was the internal standard. The migration times for procaine and tetracaine were 1.25 and 1.36 min, respectively. The limit of quantification for tetracaine was 50 µg, with a signal‐to‐noise ratio greater than 10. The calibration curve was linear from 50 to 1200 µg with r² greater than 0.99. The CV for both within‐ and between‐assay imprecision and the percentage inaccuracy for the quality control samples including lower and upper limits of quantitation were <12.1% and <11%, respectively. The absolute mean recovery of tetracaine was >97%. The accuracy and selectivity of this method allowed the rapid measurement of tetracaine in tape samples obtained from a skin tape stripping study of local anaesthetics in healthy subjects. Copyright © 2008 John Wiley & Sons, Ltd.     

Coated conductors containing grains with big aspect ratios

It is shown that the critical currents of high‐T_csuperconducting tapes fabricated by the coated conductor technologies are enhanced considerably if grain arrangements with large effective grain boundary areas are used. Increasing the aspect ratios of the grains reduces the deleterious effects of the grain boundaries. A practical road to competitive high‐T_ccables is proposed.     

126Ce的EC/β＋衰变

利用187 MeV的40Ca离子轰击同位素靶92Mo,由熔合蒸发反应生成目标核126Ce。藉助氦喷嘴快速带传输系统和X-X-t与X-γ-t符合测量,首次建立了126Ce的EC/β＋衰变纲图。建议了可能属于126Ce一个高自旋同核异能态的衰变,其β衰变后布居在与126La的高自旋同核异能态相关的低位能级区,测定的半衰期是57（9）s。也建议了可能属于126Ce基态的衰变,其β衰变后布居在与126La的低自旋同核异能态相关的低位能级区,它的半衰期被测定为12（4）s。但偶-偶核126Ce存在高自旋同核异能态的物理原因还有待进一步探究。     

Calculation of AC losses in HTSC wires with arbitrary current voltage characteristics

A method for the calculation of magnetic field dynamics and AC losses in superconductors with smooth current–voltage characteristics is described. It is based on an integral equation for the current density, recently used by Brandt for magnetic relaxation. Brandt's equation is generalized to include arbitrary external magnetic fields and transport currents. One of the benefits of the integral equation formulation is that no boundary conditions ‘at infinity' are required, thus restricting the calculation region to the conductor cross section. The method is applied to superconducting tapes in oblique external fields. A further extension of the theory is shown to be applicable to the calculation of coupling losses in twisted multifilamentary superconductors.     

Heat propagation and stability in a small high Tc superconductor coil

Using a Bi-based small high T_c superconductor (HTSC) coil, we have studied its stability against a local disturbance and current-induced quench in the helium gas cooling condition. While the stability margin of HTSC coil against a local disturbance was very large, quench current was limited by a catastrophic temperature rise which originated from the nonlinear characteristic of the Joule heating. The crucial parameter for the quench becomes the nonlinear resistance in HTSC as a function of temperature and transport current. It has been shown that the dynamic characteristics of the quench can be described quantitatively by the simplified one-dimensional heat balance equation.     

AC losses in multifilamentary Bi(2223) tapes with an interfilamentary resistive carbonate barrier

For the most common AC application frequencies, the main component of the AC losses in multifilamentary Bi(2223) tapes are caused by hysteresis- and coupling losses. These losses can be reduced enhancing the matrix resistivity and applying a twist to the filaments. We report on the AC loss properties of 37-filament tapes with AgAu (8 wt.%) matrix, and novel 19-filament tapes with SrCO₃ barriers between the filaments. We performed transport AC loss and magnetic AC loss measurements in parallel and perpendicular magnetic fields. Both kinds of tapes were also prepared with filament twists below a twist pitch of 20 mm. The influence of the different tape modifications on the AC loss behaviour is presented and compared with theoretical models to understand the effect of the resistive matrix. In the case of magnetic AC loss measurements, reduced AC losses due to decoupled filaments were observed for the twisted tapes with a resistive matrix in low parallel fields.     

带状螺旋线研究中的坐标变换

分析了带状螺旋线行波管中电磁场分量在柱坐标系下的Floquet形式，证明适当的坐标变换是电磁场分量写成变量分离形式的充分条件.螺旋带平面展开后，应用坐标变换得到的电磁场分量变量分离形式是去除面电流分布假设的理论基础.计算并分析了一个典型结构的色散和耦合阻抗，计算结果与实验结果有很好的一致. 关键词： 螺旋带 坐标变换 色散 耦合阻抗     

Optimization of the two-phase separation process in flow-injection analysis with an electron-capture detection system

A liquid-gas-phase tubing separator was designed and its operation studied in comparison with a PTFE tape-based separator. The relative efficiencies of the two separators were compared after injection into the carrier solution of a sample containing free chlorine using a chromatographic electron-capture detector for detection in the gaseous phase. The membrane separator contained porous PTFE tape whereas the tubular separator consisted of microporous PTFE membrane tubing. The two separators were compared with respect to sensitivity and reproducibility, simplicity of design and liability to interferences. Linear ranges and free chlorine detection limits were established for each of the two separators, that of the PTFE tape-based separator being 100 μg 1^?1 and that of the tubing device 50 μg 1^?1.