大面积硅锂漂移探测器制备及其性能

制备了大面积硅锂漂移探测器,其性能为:探测器的灵敏面积123.6 cm~2;灵敏层深度2 mm;在室温和300 V反向偏压的工作条件下漏电流小于20 μA;对~(241)Am 5.486 MeV α粒子的能量分辨(FWHM)为77.67 keV。     

Modelling and Simulation of a Direct Contact Rotary Dryer

A mathematical model able to predict solid and drying gas temperature and moisture content axial profiles along a direct contact rotary dryer was developed. The study was focused on the drying kinetics based on phenomenological models. Two different drying mechanisms in the decreasing drying rate period were tested: proponional to the unbound moisture content and moisture diffusion inside the particle. Experimental data collected in a pilot-scale direct contact rotary dryer was used to validate the model. Soya and fish meals were used as drying material.     

Analysis of MTF degradation in the imaging of cells in a flow system

The time-delay and integration method can be used with a charge-coupled device array to acquire images of cell in a flow cytometer. The loss of high spatial frequency components in images acquired with this technique is studied by deriving the modulation transfer function (MTF) for each of the main causes of image degradation: finite sampling aperture, nonsynchronism between image movement and charge transfer rate, discrete charge motion, transfer inefficiency, and axis misalignment. The system MTF and resolution in the horizontal and vertical directions are then examined.©1994 John Wiley & Sons Inc     

Nonlinear distortion prediction of active filters

The represention of circuit variables in frequency-domain complex matrix and nonlinearities by power series gives rise to a nonlinear distortion prediction technique, the intermodulation-balance method. This operates entirely in the frequency domain. The technique is verified by a single-amplifier filter with a two-tone input signal     

Influence of the surface conditions on permeation in the deuterium–MANET system

The condition of the surfaces is of crucial importance for the deuterium permeation through materials. In this work a study of the surface constants for the adsorption (σk₁) and release (σk₂) of deuterium under different surface conditions on the martensitic steel DIN 1.4914 (MANET) has been carried out. The growth of an oxide surface layer (Cr₂O₃) of about 25–30 nm in a MANET sample, heat treated in an oxidizing environment, compared to the bare MANET that have a ‘natural' oxide of about 5 nm has provoked a reduction of both the permeation rate and the recombination coefficient (about 3 orders of magnitude). In addition, the permeation governing process has changed from diffusion-limited to surface-limited. The measurements of the permeation rate of deuterium were performed by a gas-phase permeation technique over the temperature range 574–746 K and for deuterium driving pressures in the range from 3 to 10⁵ Pa.     

Linear predictive receivers for fading channels

The authors discuss maximum likelihood sequence detection (MLSD) based on prediction techniques for linearly modulated digital signals transmitted over fading channels. Efficient implementations of the sequence detector are investigated and a general formulation for computing the prediction coefficients is derived. Furthermore, the equivalence of different existing prediction-based receivers is shown     

IrLAP protocol performance analysis of IrDA wireless communications

The IRDA IrLAP protocol is analytically modelled. Throughput performance is examined with bit error rate, window size, and turnaround times. It is shown that for the proposed 16 Mbit/s and 127 frame maximum window size extension the link BER quality becomes critical if maximum throughput is to be achieved. A window size of 60 is less sensitive to bit error rate variations. Reducing the minimum turnaround time is always beneficial     

An analysis of distributed feedback structures in ion exchangedwaveguides

The performance of distributed feedback (DFB) structures fabricated on ion exchanged waveguides has been numerically analyzed. Waveguide exchange time, grating order, period, number of periods, grating shape, and grating depth have been included as variables for the analysis. The results are for K⁺-Na⁺-type systems exchanged at 385°C     

Statistical properties of out-of-frame detection schemes fordigital transmission systems

The importance of the misframe times for DS1 frame synchronization has often been addressed in designing and using network elements and mediation units. By extending the work of J. H. Eu and W. W. Rollins (1991), Markov chain first passage time analysis is used to derive higher moments of the misframe times in both random and burst error environments. This methodology is of great value in evaluating frame synchronization techniques for digital transmission systems. By experimenting with several out-of-frame detection schemes and reasonable values for bit error ratio (BER), it is shown that misframe times are always approximately exponentially distributed for all schemes     

Pyrene oxidation as a model reaction for characterizing the mechanism of coke oxidation on Y zeolites

The same effect of temperature on the production of CO, CO₂ and H₂O was found during oxidative treatment of HY zeolites either impregnated with pyrene or coked. Therefore, pyrene oxidation can be used to specify the mechanism of coke oxidation. Three types of reactions can be distinguished: (a) condensation of polyaromatic molecules, (b) oxidation of polyaromatics into aldehydes, ketones, acids and anhydrides and (c) decarbonylation or decarboxylation of oxygenated compounds, all these reactions involving protonic sites.