Comparison of various safety guidelines for electronic article surveillance devices with pulsed magnetic fields

The paper uses the two methods suggested in both the ICNIRP and proposed IEEE safety guidelines for compliance testing of security systems based on time-varying magnetic fields being introduced for electronic article surveillance (EAS), radiofrequency identification, and other applications. For nonsinusoidal pulses that are often used, the two procedures are to treat the exposure as a multifrequency exposure with various frequency components or to calculate the peak induced current densities or electric fields treating the highest of the pulses of duration t(p) as a single frequency, half sinusoid of the same duration and frequency 1/(2t(p)). Using either of the procedures, the induced current densities (J) or electric fields (E) are compared to the basic restrictions on J or E for compliance testing. Using a heterogeneous, tissue-classified anatomic model of the human body, we calculate the induced J and E for the various tissues for a realistic, EAS system for two typical nonsinusoidal pulses to show that the two methods give substantially different results. While the approximate but simpler method of treating the pulse as a half sinusoid results in peak induced J or E that may be compliant with safety guidelines, the rigorous method of treating such exposures as multifrequency exposures gives induced current densities or electric fields that may be up to twice as large, thus making such systems potentially noncompliant with the safety guidelines. Since it is more accurate, it is suggested that safety assessment based on the Fourier analysis leading to multifrequency components be used for compliance testing of such devices.     

Characterisation of bubble materials

The rapid development of magnetic bubble technology has required growth to exacting specifications of a large number of magnetic films of garnets and some amorphous binary and ternary alloys of rare-earth and transition metals. The characterisation of these films is an essential part in the search for newer materials which hold out promise for better device performance and cost viability. Many methods of films characterisation have been reported from time to time. By and large, these methods can be divided into two groups: one, bulk measurements made on the film and two, measurements made on the domains. We have attempted to collate and briefly introduce various techniques to characterise magnetic bubble materials in this review.     

Organic photoconductors: Dark and photoconduction studies in two p-dimethylamino styryl dyes derived from pyridine-2 and pyridine-4

Results of our experiments on the dark and photoconduction studies in two p-dimethylamino styryl dyes derived from pyridine-2 (PDMS-P2) and pyridine-4 (PDMS-P4) in their pure form without any dopant or additive are reported. Measurements on surface-type (raster pattern) cells show that the dark and photocurrents are dependent on the applied potential, temperature, and the photocurrent on the intensity of the incident radiation and the wavelength. Action spectra of the samples could not be recorded as the intensity of the monochromatic radiation from the monochromator reaching the sample was too low to induce any noticeable photocurrent. The compounds show a low dark conductivity. The dark and photocurrents show a perfect ohmic behaviour in the temperature range studied (288–328 K). Since photoconduction could only be observed in a vacuum, this clearly indicates that the compounds are n-type semiconductors. The observed rise and decay kinetics of the photocurrents indicate the presence of traps in the forbidden zone. The dyes show an enhanced photoconduction on illumination with visible radiation only. The marked open circuit voltage and the short-circuit current observed in these compounds indicate a possible application in solar photovoltaics.     

Dielectric relaxator behaviour of the system Sr1−xLaxTi1−xCoxO3 (x ⩽ 0.40)

The dielectric behaviour of the valence-compensated solid solution Sr_1–x La _x Ti_1–x Co_xO₃ (x=0.05, 0.10, 0.20, 0.30 and 0.40) has been studied as a function of temperature and frequency. Compositions withx=0.20, 0.30 and 0.40 exhibit high values of dielectric constant. This high dielectric constant is due partly to the presence of interfacial polarization, and partly to the formation of grain-boundary barrier layers in these materials. The presence of barrier layers is shown by complex plane impedance analysis.     

非易失性可无限次配置的PLD

一、ispXPGA和ispXPLD产品系列iSPXPGA FPGA(Field Programmable Gate Array 现场可编程门阵列)和ispXPLD PLD(Programmable Logic Device 可编程逻辑器件)产品的种类丰富，并以其强大的功能性获得了广泛的应用。该类产品基于SRAM(Static Random Access Memory 静态随机读写存储器)系列产品，允许被重新配置无     

Magnetic and catalytic properties of sintered nickel catalysts for the methanation reaction

Ni catalysts supported on Al₂O₃, as received commercially and subjected to sintering at 723–973 K, were characterised in terms of distinct magnetic structures. It was found that the Ni on all the catalysts consisted of a mixture of single domain structures, with and without anisotropic effects, and multidomain (ferromagnetic) structures. The formation of the multidomain particles during the sintering process coincides with a decrease in catalytic activity for the reaction CO+3H₂°CH₄+H₂O. From this study it was concluded that the methanation reaction is ‘magnetic-structure’ sensitive.     

General Approach to Dynamic Analysis of Rotorcraft

This paper presents a general‐purpose mathematical formulation for the dynamic analysis of a rotorcraft consisting of flexible or rigid components, or both, that may undergo large rotations. In this formulation, two sets of coordinates are used, namely rigid‐body coordinates and elastic coordinates. The rigid‐body coordinates define the location and the orientation of a body frame with respect to an inertial frame. The rigid‐body rotational coordinates may be Euler angles, Euler‐like angles, or Euler parameters. The elastic coordinates define the elastic deformations with respect to the body frame. Nonlinear strain‐displacement relations are considered in order to be able to incorporate the effect of geometric stiffening. A systematic methodology that combines the traditional finite element and multibody approaches is developed to obtain a set of differential and algebraic equations governing the dynamics of the system. The resulting set of equations is highly nonlinear. Numerical schemes to solve this set of equations are also discussed. The formulation presented is general and allows the development of a modular code. The formulation also allows the code to be updated and grow without reformulation of the problem.     

Valence compensated perovskite oxide system Ca1−xLaxTi1−xCrxO3 Part II Electrical transport behavior

Electrical transport behaviour of the valence compensated system Ca_1–x La _x Ti_1–x Cr _x O ₃ (x 0.50) has been investigated by studying the Seebeck co-efficient, DC and AC conductivity as a function of temperature. Seebeck co-efficient, DC conductivity of different compositions has been measured in the temperature range 300 K–1000 K. AC conductivity for different compositions were determined in the temperature range 100–550 K and frequency range 10 Hz–10 MHz. Positive values of Seebeck co-efficient show that holes are the majority charge carriers. Conduction seems to occur by correlated barrier hopping of holes among Cr³⁺and Cr⁴⁺ions or V_O and V_O . Almost equal values of activation energies obtained for DC conductivity and dielectric relaxation process show that both the processes occur by the same mechanism.     

Rhamnolipid–Metal Ions (CrVI and PbII) Complexes: Spectrophotometric,Conductometric, and Surface Tension Measurement Studies

The formation of rhamnolipid complexes with metal ions of chromium (VI) and lead (II) has been studied spectrophotometrically, conductometrically, and by surface tension measurement. The values of the critical micelle concentration (CMC) of rhamnolipid, obtained by spectroscopic, conductometric, and surface tension measurements, were 5.2 × 10⁵ , 5.0 × 10⁵ , and 5.3 × 10⁵ mol.dm⁻³, respectively, which are in close agreement. An increase in CMC on increasing metal ion content in the rhamnolipid solution and a shift in λ_max in the spectra of rhamnolipid indicated the formation of a complex between rhamnolipid and both the metal ions, namely, chromium (VI) and lead (II). The values of stability constants for the {rhamnolipid–chromium (VI)} and {rhamnolipid–lead (II)} complexes have been determined by spectroscopic data and were as 0.58 × 10⁴ and 0.50 × 10⁴ at 308 K, respectively. The thermodynamic parameters for micellization, namely, free energy change (∆G_mic) , entropy change (∆S_mic) , and heat enthalpy change (∆H_mic) , have been determined by conductivity measurements. An increase in the negative value of ∆G_mic and a decrease in the value of ∆S_mic on increasing metal ion content in the surfactant solution indicated lower micellization of rhamnolipid in the presence of metal ions. The electrostatic attractions and entrapment of chromium (VI) in the micelles of the biosurfactants were found to be responsible for {rhamnolipid–lead (II)} and {rhamnolipid–chromium (VI)} complexes, respectively.