高跨导常断GaN MODFET

成功地制作出常断ＧａＮ基ＭＯＤＦＥＴ（调制掺杂ＦＥＴ）。该器件的栅长和沟道长度分别为３和５μｍ，其非本征跨导高达１２０ｍＳ／ｍｍ，在正栅偏压为３Ｖ时其电流为３００ｍＡ／ｍｍ。该跨导值与先前报道的栅长分别为１和０．２３μｍ、跨导分别为４５和２４ｍＳ／ｍｍ的器件相比，是相当不错的。     

Fractional-Fourier-transform calculation through the fast-Fourier-transform algorithm

A method for the calculation of the fractional Fourier transform (FRT) by means of the fast Fourier transform (FFT) algorithm is presented. The process involves mainly two FFT's in cascade; thus the process has the same complexity as this algorithm. The method is valid for fractional orders varying from -1 to 1. Scaling factors for the FRT and Fresnel diffraction when calculated through the FFT are discussed.     

ITMA 2007: 非织造产品生产技术(第一部分)

1 总体趋势 1.1 全套生产线的供应 纵观非织造行业的四大集团--Dilo,NSC,Trützschler和Oerlikon Neumag,显然其中每一家都能立刻提供用于加工短纤维非织造布的全套生产线.这四家集团现在都可为客户提供全套技术装备和支持的交钥匙工程服务.     

Segmentation of retinal blood vessels by combining the detection of centerlines and morphological reconstruction

This paper presents an automated method for the segmentation of the vascular network in retinal images. The algorithm starts with the extraction of vessel centerlines, which are used as guidelines for the subsequent vessel filling phase. For this purpose, the outputs of four directional differential operators are processed in order to select connected sets of candidate points to be further classified as centerline pixels using vessel derived features. The final segmentation is obtained using an iterative region growing method that integrates the contents of several binary images resulting from vessel width dependent morphological filters. Our approach was tested on two publicly available databases and its results are compared with recently published methods. The results demonstrate that our algorithm outperforms other solutions and approximates the average accuracy of a human observer without a significant degradation of sensitivity and specificity.     

Influence of carcass weight on instrumental and sensory lamb meat quality in intensive production systems

The effects of cooking viz. pressure-cooking and broiling and storage at 4 °C for six days and -10 °C for 90 days on lipid oxidation and development of cholesterol oxidation products in mutton were studied. Results revealed that cooking of meat significantly increased the total lipids, phospholipids, cholesterol, glycolipids, free fatty acids and glycerides, but they did not change during refrigerated and frozen storage. The TBA values increased on cooking and during storage. However, the values were below the threshold level for rancidity development. The following cholesterol oxidation products were separated by thin layer chromatography cholestanetriol, 7-α-hydroxy cholesterol, 19-hydroxycholesterol, 7-ketocholesterol, cholesterol-α-epoxide, cholesterol-β-epoxide and an unidentified fraction. All these fractions except the unidentified fraction increased on cooking. On refrigerated and even on frozen storage all these fractions increased except the unidentified fraction, which showed a concomitant reduction. The changes in broiled meat were more pronounced compared to pressure-cooked meat. Results clearly indicated that even frozen storage of cooked meat did not prevent the development of cholesterol oxidation products.     

An application of scanning electron microscopy combined with roentgen microanalysis (SEM-EDS) in canine urolithiasis

Urolithiasis is a common diagnostic and therapeutic problem in small-animal veterinary practice. The traditional diagnostic approach usually consists of clinical, radiological and ultrasonographic examination of the patient. The main diagnostic material is still urine sediment, ignoring the fact that presence of crystalluria is not always of pathological significance. In order to establish the most effective therapeutic and preventative strategies, especially in the case of multicomponent stone, it is crucial to define the exact elemental composition of the given stone including crystallization nidus chemical contents. In the course of the research, the usefulness of scanning electron microscopy combined with X-ray-dispersive spectrometry in analysis of canine mixed and compound stones was investigated. The obtained results indicated that the tested method allows one to trace the dynamics of the crystallization process, including crystallization nucleus detection, and concurrently and quantitatively assess the elemental composition of the given urinary concrement. Moreover, the conducted research showed epidemiological data of urolithiasis occurrence in a population of dogs coming from the southern part of Poland.     

An anisotropic microsphere-based approach for fiber orientation adaptation in soft tissue

Evolutionary processes in biological tissue, such as adaptation or remodeling, represent an enterprising area of research. In this paper, we present a multiscale model for the remodeling of fibered structures, such as bundles of collagen fibrils. With this aim, we introduce a von Mises statistical distribution function to account for the directional dispersion of the fibrils, and we remodel the underlying fibrils by changing their orientation. To numerically compute this process, we make use of the microsphere approach, which provides a useful multiscale tool for homogenizing the microstructure behavior, related to the fibrils of the bundle, in the macroscale of the problem. The results show how the fibrils respond to the stimulus by reorientation of their structure. This process leads to a stiffer material eventually reaching a stationary state. These results are in agreement with those reported in the literature, and they characterize the adaptation of biological tissue to external stimuli.     

茂金属耐热聚乙烯管材料的结构与性能

对3种茂金属耐热聚乙烯（PE-RT）管材料（ M 1,M 2和M 3）的基本物性、热性能、相对分子质量及其分布、力学性能、流变性能等进行分析表征,考察了3种PE-RT管材料的性能差异。结果表明: 3种PE-RT管材料均属于中密度聚乙烯产品,熔体流动速率相近;3种PE-RT管材料中,国产料M 1,M 2的分子质量分布较宽,熔点较低,结晶度小,韧性较好;进口料M 3的熔体拉伸强度较大,可拉伸性最佳,弯曲弹性模量高,具有良好的刚性。     

柴油加氢改质装置掺炼催化柴油

为解决中国石油兰州石化公司90万t/a柴油加氢改质装置开工后出现的原料与热量不足的问题,进行了掺炼催化柴油的工业试验。结果表明:当催化柴油掺炼比（质量分数）为10%,裂化反应器第1~第4床层温升依次为7,8,5,6 ℃时,航空煤油收率与柴油转化率最高。与掺炼前相比,掺炼10%催化柴油后,装置能耗由19.48 kg/t（以标准油计）提高至19.96 kg/t;产物中气相、轻重石脑油与航空煤油收率增加;精制柴油收率下降;重石脑油中环烷烃、芳烃质量分数分别提高了2.11,1.67个百分点;航空煤油冰点降低了10 ℃,烟点降低了8.2 mm;精制柴油的质量得到改善。     

热灌装饮料瓶用丙丁共聚聚丙烯的结构与性能

采用高温凝胶渗透色谱（GPC）仪、差式扫描量热（DSC）仪、偏光显微镜等分析了热灌装饮料瓶用丙丁共聚聚丙烯（牌号PB 13 HF,简称试样1）的结构与性能,并与相应的市售产品（牌号为E 980 BHF,简称试样2）性能进行了对比分析。结果表明:试样1与试样2的相对分子质量及其分布相近;与试样2相比,试样1的熔融结晶性能略有提高,热变形温度、拉伸屈服应力、弯曲应力等刚性较好,冲击强度略低,雾度相近。