The thermal stability of Ni-11 wt% P metallic glass

A study of the crystallization of the metallic glass Ni₈₁P₁₉ was undertaken. A portion of the crystallization time-temperature-transformation curve was determined and compared with curves published by other authors. The composition and structure of the as-received metallic glass was determined. Crystallization kinetics of the glass and activation energy data were determined. Crystallization of the glass involved nucleation and growth of the crystalline phase from both the surface of quenched-in crystals and the bulk of the material. The activation energies obtained were similar for incubation, nucleation and growth. This along with supporting experimental evidence suggests that there is no activation barrier to nucleation and that all stages of crystallization are controlled by diffusion.     

The pattern of residual muscle paralysis in poliomyelitis

Rural schoolchildren between the ages of 6 and 18 years were screened for residual paralysis following poliomyelitis; 503 (0.85%) out of a total of 58,592 were victims. Of these, only 16 (3.8%) had received poliomyelitis vaccine, while the remainder had not been immunised. The disease had occurred before the age of 4 years in nearly 90%, the lower limbs being affected (98%) more often than the upper (2%). In the lower limbs, the quadriceps, hip adductors and tibialis anterior were frequently affected. The muscles supplied by the L4 and L5 spinal segments were most commonly involved, while those supplied by L1 and S3 were least. Some order does exist in the apparently irregular distribution of paralysis after poliomyelitis.     

Optimization of ingredients for the manufacture of soft-serve ice-cream (Softy) by response surface methodology (RSM)

Soft ice-cream samples were prepared with different proportions of cream and skimmed milk powder (SMP) and were examined for quality by physico-chemical parameters and sensory attributes. The specific proportions of cream and SMP were designed using the central composite rotatable design (CCRD). Response surface analysis indicated that sensory flavour, texture and overall acceptability (OAA) scores of soft ice-cream varied from 7.12 to 8.86, 6.66 to 8.03 and 6.90 to 8.45, respectively. The differences in the sensory scores for respective attributes were highly significant ( P ≤  0.01). The soft ice-cream containing a minimum level of 3.24% cream and 4.94% SMP resulted in a product having a minimum of 4.3% fat, 5.7% lactose and 33% total solids, with a minimum OAA score of 8. The derived mathematical second-order polynomial models against cream (X) and SMP (Y) were found to be adequate as coefficients of multiple determinants ( R ²) were more than 80% except for melting resistance.     

An Improved On-Wafer Measurement Method for PHEMT Modeling for Millimeter Wave Application

An improved on-wafer measurement method by using coaxial calibration instead of on-wafer calibration for PHEMT modeling is proposed in this paper. The advantage is that S-parameters of PHEMT device can be measured on wafer without impedance standard substrate (ISS) after the S-parameters of the microprobes have been determined. Excellent agreement is obtained between on-wafer calibration measurement and coaxial calibration measurements, respectively.     

A new method for pHEMT noise-parameter determination based on 50-/spl Omega/ noise measurement system

A new method for determining the four noise parameters of pseudomorphic high electron-mobility transistors (pHEMTs) based on a 50-/spl Omega/ noise measurement system without a microwave tuner is presented. The noise parameters are determined based on the noise correlation matrix technique by fitting the measured noise figure of the active device. On-wafer experimental verification up to 26 GHz is presented and a comparison with a tuner-based method is given. The scaling rules for noise parameters have also been determined. Good agreement is obtained between simulated and measured results for 2/spl times/20 /spl mu/m, 2/spl times/40 /spl mu/m, and 2/spl times/60 /spl mu/m gatewidth (number of gate fingers /spl times/ unit gatewidth) 0.25-/spl mu/m double-heterojunction /spl delta/-doped pHEMTs.     

Viscosity of homogeneous polymer blends: An altered free-volume state model

An altered free-volume state (AFVS) model was developed for the zero-shear viscosity of homogeneous polymer blends. The model involves a single adjustable parameter and is capable of predicting several complex features of the blend viscosity-composition behavior. These include negative and positive deviations from additivity, maxima, minima, and sigma-shaped curves. The validity of the model was tested by comparison of the model predictions with experimental data for several homogeneous blend systems. It is shown that the model is valid within a broad molecular weight range and is more accurate than some of the currently accepted models such as the kinetic network model. Besides, it appears that the AFVS model also may be applicable to blends of incompatible polymers under certain conditions.     

A versatile power converter for high-frequency link systems

A single-phase high-frequency link appears to be an attractive alternative to the DC link commonly used in power conversion systems. The authors propose a power converter suitable for one-step conversion of the single-phase high-frequency link voltage to the three-phase low-frequency voltages typically required for interfacing with system sources and loads. The converter utilizes zero voltage switching principles to minimize switching losses and uses an easy-to-implement technique of pulse density modulation for the control of the amplitude, frequency, and waveshape of the synthesized low-frequency signals. Adaptation of the proposed topology for power conversion to single-phase AC and DC voltage or current outputs is shown to be straightforward. The feasibility of the proposed power circuit and the control technique have been experimentally verified     

Heavy media separation of SRC-II feedstocks: 1. Effect on coal properties

The objectives of this investigation were to determine the effects of coal preparation on the properties of Run-of-Mine (ROM) and washed Powhatan and Ireland Mine coals and to assess the potential effects on SRC-II liquefaction yields. The effect of washing on the two coals was found to be quite similar. For both coals, the properties were altered more significantly by changes in separation media gravity than by changes in the coal size. The elemental composition of the Powhatan and Ireland washed coals was correlated with carbon content. It was shown that both the hydrogen and oxygen levels increased linearly with the carbon content of the coal samples. However, the $\text{H}\text{C}$ and $\text{O}\text{C}$ ratios were not changed significantly by coal cleaning. Only small variations in the nitrogen and organic sulphur levels were observed while the sulphate sulphur and chlorine levels were not affected by coal cleaning. The major impact of the coal cleaning was to reduce the pyritic sulphur (and hence the total sulphur) content of the coals. Most of the pyritic sulphur was shifted into the middling coal and refuse fractions while the clean coals had much lower contents and the pyritic sulphur level decreased with increasing carbon content. Coal cleaning did not significantly alter the maceral contents of vitrinite, exinite, total reactive macerals (TRM), or the reflectance of vitrinite; all these parameters varied over a very narrow range, probably within the precision of the measurement technique.