一种宽频带,近场馈电的机械扫描平面（圆盘）反射器天线

本文分析了一种宽频带，近场喇叭馈电的平面圆盘反射器机械扫描天线。天线的组成见图1。平面圆盘被处在近场区域中的喇叭照射．并绕着喇叭轴旋转使圆盘散射场形成的波瓣在水平面内扫描。采用矢量Kirchhoff公式计算由喇叭照射在圆盘表面引起的磁场，并应用物理光学方法计算圆盘产生的散射场，即圆盘的散射波瓣，其中还包括喇叭的直接辐射场。计算结果基本上与实测结果吻合。因此本文的方法可用于宽频带，机械扫描平面反射器天线的设计。     

Geometric Simultaneity and the Continuity of Special Relativity

In this note I briefly discuss some aspects of relative geometric simultaneity in special relativity. After saying a few words about the status and nature of Minkowski spacetime in special relativity, I recall a uniqueness result due to David Malament concerning simultaneity relative to an inertial worldline and an extension of it due to Mark Hogarth and I prove an extension of it for simultaneity relative to an inertial frame in time-oriented spacetimes. Then I point out that the uniqueness results do not generalise to definitions of simultaneity relative to the rotating disk. Finally, I evaluate some recent claims of Selleri in the light of the results. Whilst some of his claims are supported by the approach taken here, the conclusion he draws from these claims, that special relativity harbours a discontinuity and so stands in need of replacement, does not follow and is rejected.     

矩阵码盘及其矩阵狭缝的检测

在介绍矩阵码盘的基础上，分析常规矩阵码盘和非常规矩阵码道图案方向的确定方法，提出矩阵码盘码道间相位关系误差的检测方法－－角量比较法和线量比较法以及矩阵码盘码道间、圈间关系误差的检测方法，阐述了阵狭缝间裂相相位关系、圈与圈之间关系误差的检测方法－－角量比较法和线量比较法，并分析在不同一刻划直径上的码间，圈间相位关系误差的检测方法，最后对测量误差进行了讨论。     

On the dielectric susceptibility of classical Coulomb systems

This paper reports exact and numerical results on the shape dependence of the dielectric susceptibility of the one-component plasma (O.C.P.) in two dimensions. Some apparently conflicting predictions of phenomenological electrostatics and statistical mechanics are resolved. We prove indeed that, for a disk shaped two-dimensional one-component plasma at the particular temperatureT ₀ =q ² (2K _B )^–1, the Clausius-Mossotti relation is exactly fulfilled. It yields a value of the susceptibility which is twice that given by the second moment Stillinger-Lovett sum rule. Similar results are reported for the strip geometry. These discrepancies are explained in terms of shape dependent versus shape independent thermodynamic limits. We report also exact and numerical results on the size dependence of the dielectric susceptibility of the systems quoted above.     

Kinetic analysis of the hydrogen oxidation reaction on Pt-black/Nafion electrode

The hydrogen oxidation reaction on Pt-black/Nafion electrode was investigated using a rotating disk electrode and cyclic voltammetry technique. The voltammetric results demonstrated that the electrode can be prepared with good reproducibility and that Pt-black particles without direct contact with Nafion were still electrochemically active in taking part in the H-adsorption/desorption process. For hydrogen oxidation, the limiting current density was reduced by the presence of Nafion coating. The H₂ diffusion resistance in Nafion film was avoided when the film thickness was less than 0.2 μm for a Pt-black loading of 20 μg. Moreover, the uncertainties in the kinetic results were discussed.     

Electric mass transfer of sodium chloride through cation-exchange membrane MK-40: A rotating membrane disk study

An experimental device consisting of a rotating membrane disk with horizontally positioned cation-exchange membrane MK-40 is described. The device’s design makes it possible to simultaneously obtain current-voltage curves (CVC) and dependences of effective transport numbers for ions of electrolyte and water dissociation products on the current density. Partial CVC are calculated and limiting current densities and diffusion layer thickness are determined at various disk rotation rates. At current densities below the limiting value, the disk’s CVC obey regularities of electrodiffusion kinetics. Upon raising the current density further, the salt ion fluxes increase due to a decrease in the effective diffusion layer thickness, which is caused by the emergence in the near-membrane region of a space charge and electroconvection. At high current densities there occur oscillations of the potential jump that are caused by hydrodynamic instability of the near-membrane solution layer.     

Investigation on the Electrochemical Polymerization of Catechol by Means of Rotating Ring—disk Electrode

The electrolysis of catechol was studied in the pH values of 1 to 10. The results from the rotating ring-disk electrode (RRDE) experiments show that at low pH values,the electrochemical polymerization of catechol was performed by one step,and at higher pH values,the electrochemical polymerization of catechol was carried out by two steps,i.e.oxidation of catechol and followed by polymerization.The intermediates generated at the disk were detected at the ring electrode in the ring potential region of -0.2 to 0 V(vs.Ag/AgCl).One of reasons for the decrease in the ratio of ir to id with increasing the ring potential is caused by formation of positively charged intermediates at the disk electrode.This ratio increases with increasing the rotation rate of the RRDE,which indicates that the intermediates are not stable.A shielding effect during polymerization of catechol was observed when the ring potential was set at 0.1 V (vs.Ag/AgCl).The electron spin resonance(ESR) of polycatechol show that polycatechol possesses unpaired electrons.The images of polycatechol films synthesized at differentconditions are described.     

Flow Injection Analysis of Chloramphenicol by Using a Disposable Wall‐Jet Ring Disk Carbon Electrode

A preanodized screen‐printed ring disk carbon electrode was applied to the determination of chloramphenicol (Ph? NO₂, CAP) by flow injection analysis (FIA). By setting up the first irreversible reduction reaction of Ph? NO₂ to Ph? NHOH at the disk electrode, the following reversible oxidation of hydroxylamine (Ph? NHOH) to the nitroso (Ph? NO) derivative can be monitored/collected at the ring electrode for CAP analysis. The interference from dissolved oxygen and others can thus be avoided by using this approach and precise CAP determination can be easily performed by FIA under aerobic conditions. Preanodization treatment helps to lower the overpotential of the electrochemical reaction of CAP and favors the selective detection in aqueous medium. Under the optimum conditions, ten repetitive determinations at 1 μM and 10 μM CAP resulted in relative standard deviations of less than 4%, indicating good reproducibility of the system. A linear calibration range of 0.1–20 μM with a detection limit of 0.074 μM (S/N=3) was obtained. Veterinary pharmaceutics were finally analyzed by this sensor to validate its practical applicability.     

Flame atomic absorption determination of palladium in solutions after preconcentration using octadecyl silica membrane disks modified by thioridazine.HCl

A new simple and reliable method for rapid and selective extraction and determination of trace level of Pd(II) ion is developed. Palladium ions are adsorbed quantitatively during passage of aqueous samples through octadecyl silica membrane disks modified with thioridazine·HCl (TRH). The influence of flow rates of eluent and sample solution, amount of ligand, types and least amount of eluent, and pH of samples were studied. Almost all matrix elements were found to pass through the disk to drain. Break through volume and limit of detection of the membrane disks modified by 5 mg of TRH was found to be 1.0 l and 12 μg l⁻¹, respectively. The retained Pd(II) ions are then stripped from the disk with a minimal amount of sulfite solution as eluent and subsequently measured by atomic absorption spectrometry. The proposed method permitted large enrichment factors of about 100 and higher. The method was applied to the recovery of Pd(II) ions from different industrial samples and waters.