基于P-N结的太阳能电池伏安特性的分析与模拟

通过分析实际P-N结与理想模型之间的差别,建立了P-N结二极管及太阳能电池的数学模型;利用Matlab中的系统仿真模块库建立仿真模型,设置参量,求解模型方程并绘制了图形.对太阳能电池在一定光照下旁路电阻及串联电阻取不同数值时对其开路电压、短路电流及填充因子的影响做了模拟,并与实际测得的硅太阳能电池伏安特性进行了比较.模型分析与实验测量的结果表明:等效的旁路电阻和串联电阻分别影响电池的开路电压和短路电流.仿真结果与实验测量结果一致.     

Polarization-dependent carrier dynamics in a passive InAs/InP quantum dot waveguide

We investigate carrier dynamics in a passive InAs/InP quantum dot (QD) waveguide using 255 fs optical pulses at a central wavelength of 1568 nm. We observe strong anisotropy of absorption saturation for different polarizations. Pump-probe measurements indicate the presence of carrier relaxation dynamics on a timescale in the order of tens of picoseconds due to cascaded relaxation of carriers generated by two-photon absorption (TPA) from the bulk region to the QDs via the wetting layer. These relaxation timescales are much longer than in QD amplifiers. Our observations are supported by a rate-equation model which includes TPA, showing good agreement with the pump-probe measurements.     

甜菜糖蜜酒精废液生产菌体蛋白饲料初探

甜菜糖蜜酒精废液含有大量的有机物，pH值低，BOD、CDO值高，直接排和会造成环境的严重污染，又损失了一些有机物，在此废液中可直接接入酵母菌，使其大量繁殖，生产出的菌体粗蛋白含量达41．7％，CDO值降低了20％以上，减轻了环境污染。     

Synchronization of a class of chaotic dynamic systems with controller gain variations

In this paper, the nonfragile control problem for synchronization of a class of chaotic dynamical systems with controller gain variations is studied. Using the Lyapunov method and LMI (linear matrix inequality) technique, a criterion for the existence of the nonfragile controller for synchronization is derived in terms of LMI. To show the effectiveness of the proposed method, the control problem is applied to Genesio chaotic system.     

Alloy formation in mechanically activated mixtures

The physical mixtures of hydroxocarbonates of Cu and Ni with aluminium were activated using a laboratory planetary mill. The chemical reactions and alloy formations as the effects of grinding were followed by the phase analysis of solid products based on the thermogravimetry and X-ray diffractometry. Experimental evidence indicates that the nature of reactions and products of mechanical activation was dependent on the amount of aluminium and time of grinding. This revised version was published online in July 2006 with corrections to the Cover Date.     

<Superscript>40</Superscript>K activities and potassium concentrations in tobacco samples of Mexican cigarettes

Nine brands of tobacco cigarettes manufactured and distributed in the Mexican market were analyzed by γ-spectrometry to certify their non-artificial radioactive contamination. Since natural occurring radioactive materials (NORM) ⁴⁰K, ²³²Th, ²³⁵U, and ²³⁹U (and decay products from the latter three nuclides) are the main sources for human radiation exposure, the aim of this work was to determine the activity of ⁴⁰K and potassium concentration. Averages of ⁴⁰K and potassium concentration were of 1.29±0.18 Bq·g⁻¹, and 4.0±0.57%. The annual dose equivalents to the whole body from ingestion and inhalation of 26 Bq ⁴⁰K were 0.23 μSv and 15.8 μSv, respectively. The corresponding 50 years committed dose equivalents was 0.23 μSv. The total committed dose to the lungs due to inhalation of ⁴⁰K in tobacco was 16 μSv. Potassium concentrations obtained in this work were in the same range of those obtained by INAA, so showing that the used technique is acute, reproducible, and accessible to laboratories equipped with low background scintillation detectors.     

Correlation between Al2O3 particles and interface of Al-Al2O3 coatings by cold spray

Al-Al₂O₃ composite coatings with different Al₂O₃ particle shapes were prepared on Si and Al substrate by cold spray. The powder compositions of metal (Al) and ceramic (Al₂O₃) having different sizes and agglomerations were varied into ratios of 10:1 wt% and 1:1 wt%. Al₂O₃ particles were successfully incorporated into the soft metal matrix of Al. It was found that crater formation between the coatings and substrate, which is typical characteristic signature of cold spray could be affected by initial starting Al₂O₃ particles. In addition, when the large hard particles of fused Al₂O₃ were employed, the deep and big craters were generated at the interface between coatings and hard substrates. In the case of pure soft metal coating such as Al on hard substrate, it is very hard to get proper adhesion due to lack of crater formation. Therefore, the composite coating would have certain advantages.     

Development of a Millimeter Wave Compact Equipment for NDT of Materials

We developed a compact equipment working at 94 GHz to replace the commonly used network analyzer for nondestructive testing of materials. The compact equipment was designed to measure the variations in the amplitude and phase of the reflected signal from the material relative to a reference signal. A good accuracy of the amplitude and phase measurement of the equipment was obtained in the confirmative experiments. The distribution of a drop of water in a wood plate is clearly visible in the millimeter wave images obtained by the amplitude and phase measurement.     

Synthesis and characterization of novel polyimides with 2,2‐bis[4(4‐aminophenoxy)phenyl]phthalein‐3′,5′‐bis(trifluoromethyl)anilide

2,2‐Bis[4(4‐aminophenoxy)phenyl]phthalein‐3′,5′‐bis(trifluoromethyl)anilide (6FADAP), containing fluorine and phthalimide moieties, was synthesized via the Williamson ether condensation reaction from 1‐chloro‐4‐nitrobenzene and phenolphthalein‐3′,5′‐bis(trifluoromethyl)anilide, which was followed by hydrogenation. Monomers such as 2,2‐bis[4(4‐aminophenoxy)phenyl]phthalein‐anilide containing phthalimide groups and 2,2‐bis[4(4‐aminophenoxy)phenyl]phthalein containing only phthalein moieties were also synthesized for comparison. The monomers were first characterized by Fourier transform infrared (FTIR), ¹H NMR, ¹⁹F NMR, elemental analysis, and titration and were then used to prepare polyimides with 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride. The polyimides were designed to have molecular weights of 20,000 g/mol via off‐stoichiometry and were characterized by FTIR, NMR, gel permeation chromatography (GPC), differential scanning calorimetry, and thermogravimetric analysis. Their solubility, water absorption, dielectric constant, and refractive index were also evaluated. The polyimides prepared with 6FADAP, containing fluorine and phthalimide moieties, had excellent solubility in N‐methylpyrrolidinone, N,N‐dimethylacetamide, tetrahydrofuran, CHCl₃, tetrachloroethane, and acetone, and GPC analysis showed a molecular weight of 18,700 g/mol. The polyimides also exhibited a high glass‐transition temperature (290 °C), good thermal stability (～500 °C in air), low water absorption (1.9 wt %), a low dielectric constant (2.81), a low refractive index, and low birefringence (0.0041). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3361–3374, 2003