Limiter discriminator detection of narrow‐band duobinary FSK in a land mobile channel

Error rates (BER) for narrow‐band duobinary FM with discriminator detection and integrate and dump (LDI) post‐detection filtering in land mobile channel characterized by fading and Doppler frequency shift are obtained. The fading process is assumed to be much slower than data rate, allowing the fading process to be analysed in a quasistatic manner as it passes through the narrow‐band filter. A simulation model was constructed using the signal processing simulator, and the simulated error rate results are shown to agree well with the calculated error rate results. Copyright © 2004 John Wiley & Sons, Ltd.     

Electric and fluid field analysis of side-drive micromotors

Motive torque, axial force, and viscous drag torque in variable-capacitance side-drive micromotors are analyzed by finite-element modeling of electric and fluid fields. For electric field modeling, the focus is on surface-micromachined salient-pole polysilicon micromotors with 12 stator poles and eight rotor poles, and their three-dimensional geometry is considered. Comparison with results of two-dimensional in-plane and axial-plane analysis of the same motors indicates that 3-D finite-element analysis (FEA) of the electric field is required to accurately calculate the motive torque and axial force acting on the rotor. The 3-D results are in good agreement with available experimental data. For fluid field modeling, a simple axisymmetric model geometry that consists of a thin flat disk is used, and the bushing, stator, and bearing are added incrementally. The viscous drag coefficient from steady-state FEA is within 30% of the value estimated from experimental measurement     

Environmentally-affected indentation fracture in poly(ethersulphone) and poly(methyl methacrylate)

The effect of plasticization on the ductile-to-brittle fracture transitions (DBFT) in the ball indentation of poly (ethersulphone) (PES) and poly(methyl methacrylate) (PMMA) has been studied. The DBFT in various organic liquids are governed by a size effect related to the indenter radius, in accordance with the Puttick theory of fracture transitions. In addition, abrasive wear rates of the polymers in these liquids are shown to correlate with the critical indenter radius needed to produce a fracture transition, owing to the connection with fracture toughness.     

A new method of preserving chicken eggs at environmental temperature

A new method of preserving eggs at room temperature is discussed. The method consists in the "plastification" in situ of the shell, using a liquid synthetic polyvinyl chloride acetate plastic. The plastified eggs and controls were stored under laboratory conditions at 22 degrees C, and the following variables were studied in relation to time: pH of the thick and fluid white, and of the yolk, loss of weight, diameter, yolk index and Haugh units. The results indicated that this new method preserves edible eggs for periods longer than 135 days.     

Mössbauer and X-ray photoelectron spectroscopic studies of heat-treated calcium borate glasses containing iron

⁵⁷Fe Mössbauer and X-ray photoelectron spectroscopic studies have been carried out on a number of iron-containing calcium borate glasses which show large changes in d.c. conductivity upon annealing. The Mössbauer spectra of the unannealed glass samples are compatible with the presence of predominantly ferric iron in a six-co-ordinate oxygen environment. Upon annealing a partial ordering of the glassy phase is found as indicated by a reduction in the linewidth of the Mössbauer resonances. Longer annealing times lead to the precipitation ofα-Fe₂O₃ clearly identified by the gradual appearance of a six-line magnetically split pattern in the Mössbauer spectra. These changes are qualitatively correlated with changes in d.c. conductivity of the samples. The binding energies and full width at half maxima of representative core levels of each element present show a remarkable consistency for all samples. Moreover the 2p spectra of iron incorporated in the glassy phase are essentially similar to that of the precipitated Fe₂O₃.     

Electrical and mechanical properties of carbon pellets from acid (HNO3)treated self-adhesive carbon grain from oil palm empty fruit bunch

Factors such as its natural properties, low cost and availability in large quantities as a by-product may give oil palm empty fruit bunches (EFB) a great potential as a candidate precursor for solid carbon products. Self-adhesive carbon grains (SACG) were prepared from EFB by a low temperature pre-carbonization process. Green pellets were prepared from SACG and SACG treated with nitric acid having concentration of 1, 3 and 5 Molar (M). Carbon pellets were produced by carbonization of green pellets up to 1000°C in a nitrogen environment using multi-step heating profile. Measurements on carbon pellets show that the electrical conductivity (), hardness (H) and Young's modulus (Y) follow the linear equations /[10^–3 × (m )^–1] = 0.57M + 4.74, H/[Vickers hardness] = 27M + 148 and Y/[GPa] = 2.6M + 5.0, respectively. This indicates that nitric acid systematically affected the properties of the product. The behavior that , H and Y increase linearly with M seems to be associated with the effect of acid treatment on the weight loss, lignocellulosic structure and particle size of the SACG.     

A new very high-speed phase comparator

The paper represents further work on phase-comparison techniques by the same author. Efforts to shorten fault clearance times are reported. The basic theory and principle of operation of a new technique of symmetrical phase-comparison for use either in phase-comparison carrier or distance protection schemes is outlined; this is defined by the no-time-delay measuring technique, in which the comparator can detect the instant of fault inception when the phase displacement between the two relaying signals exceeds the trip angle of the system and delivers a trip issue with no time delay. One of its most important advantages is the possibility of minimal fault detection times over the whole of the area covered by a particular relaying characteristic.An example is given of the application of the comparator to a mho characteristic distance relay (90° trip angle) for the protection of a typical 500 kV double-circuit transposed line section of 100 km length. The relay circuitry is described. Steady state and dynamic fault tests were performed using the protective gear test bench. The results confirm the validity of the measuring concept.     

High velocity SAW using aluminum nitride film on unpolished nucleation side of free-standing CVD diamond

High performances surface acoustic wave (SAW) filters based on aluminium nitride (AlN)/diamond layered structure have been fabricated. The C-axis oriented aluminum nitride films with various thicknesses were sputtered on unpolished nucleation side of free-standing polycrystalline chemical vapor deposition (CVD) diamond obtained by silicon substrate etching. Experimental results show that high order modes as well as Rayleigh waves are excited. Experimental results are in good agreement with the theoretical dispersion curves determined by software simulation with Green's function formalism. We demonstrate that high phase velocity first mode wave (so-called Sezawa wave) with high electromechanical coupling coefficient are obtained on AlN/diamond structure. This structure also has a low temperature coefficient of frequency (TCF), and preliminary results suggest that a zero TCF could be expected.