Gamma irradiation of cowpea (Vigna unguiculata L. Walp) seeds: effect on colour,cooking quality and pasting characteristics

Cowpea seeds were treated to various gamma irradiation doses, and their colour, cooking quality and pasting properties studied. Irradiation at 50 kGy resulted in significant browning (indicated by decreases in L colour value) of cowpea seeds. At 2 and 10 (but not at 50) kGy, irradiation led to significant reduction in cooking time of cowpea seeds possibly through irradiation‐induced degradation of starch and pectic substances (indicated by decreases in peak and final viscosities) leading possibly to enhanced heat and mass transfer within the seed cotyledon and cell wall, respectively. At 50 kGy, the cooking time of cowpea seeds was prolonged significantly owing possibly to extensive polymer cross‐linking occurring within the seeds at this high dose. Splitting of cowpea cotyledons during cooking decreased significantly at 50 kGy, but was unaffected at 2 and 10 kGy. Irradiation resulted in significant leaching of nutrients from cowpea seeds during cooking in a dose‐dependent manner.     

Gamma norm minimization based image denoising algorithm

Focusing on the issue of rather poor denoising performance of the traditional kernel norm minimization based method caused by the biased approximation of kernel norm to rank function,based on the low-rank theory,a gamma norm minimization based image denoising algorithm was developed.The noisy image was firstly divided into some overlapping patches via the proposed algorithm,and then several non-local image patches most similar to the current image patch were sought adaptively based on the structural similarity index to form the similar image patch matrix.Subsequently,the non-convex gamma norm could be exploited to obtain unbiased approximation of the matrix rank function such that the low-rank denoising model could be constructed.Finally,the obtained low-rank denoising optimization issue could be tackled on the basis of singular value decomposition,and therefore the denoised image patches could be re-constructed as a denoised image.Simulation results demonstrate that,compared to the existing state-of-the-art PID,NLM,BM3D,NNM,WNNM,DnCNN and FFDNet algorithms,the developed method can eliminate Gaussian noise more considerably and retrieve the original image details rather precisely.     

脉冲中子水流测井技术在注聚井注入剖面测试中的应用

注聚井注入剖面测井受粘度等诸多因素影响,一直是近年来需要测井技术人员解决的一个测试难题.文章介绍了脉冲中子水流测井技术-测井仪器的工作原理、测试方法及其测试应用效果,说明该技术不仅可以准确测量注聚井注入剖面,而且可以在注聚井找窜、找漏、判断漏点位置等方面具有指导作用,有效解决了注聚井的测试难题,为油田开发提供了可靠的科学数据资料.     

A new inexpensive method for the preparation of acicular precursors for magnetic recording media

Magnetic materials meant for audio/video recording applications necessitate that polycrystalline materials be in acicular shape. So preparation of acicular precursors for magnetic storage materials assumes significance. The employment of aqueous solutions do not produce needle shape crystallites. Glycerol is one of the complexing media used for the precipitation of ferrous oxalate dihydrate. An inexpensive method using starch for preparation of acicular particles is described. The influence of an additive namely Gd on acicularity is also investigated.     

Solution growth of cadmium telluride

Cadmium telluride crystal has been grown by solution method from Te-rich (Cd_0·3Te_0·7) melt. Ingots having 9 mm diameter and length up to 30 mm were grown by cooling the melt slowly (1°C/h) under a vertical temperature gradient of about 30°C/cm. As-grown ingots were characterized for optical transmission and resistivity. The middle portion of the ingots exhibited better optical transmission properties. Resistivity (p-type) was found increasing, towards the last-to-grow end, from 10³ to 10⁶ Θ-cm. Surface barrier type of detectors, made from low resistivity (≅ 10⁴Θ-cm) materials, were found suitable for detection ofX- and low energy gamma radiations. In case of high resistivity (≅10⁶Θ-cm) detectors, the performance was seen to be affected by polarization. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

欠采样频率估计方法

基于时延和旋转不变子空间技术(ESPRIT),本文提出了一种新的欠采样宽频带信号频率的高分辨估计方法.文中,欠采样所引入的频率模糊由增加的延迟通道提供的信息加以消除,并提出了相应的频率解模糊算法.为进一步降低运算量,文中给出了该频率估计方法的简易算法,增强了方法的实用性.文末推导给出频率估计的CRLB,并通过数值仿真实验验证了本文算法的有效性.     

Preparation and characterization of the copolymers obtained by grafting of monoacryloxyethyl phosphate onto polytetrafluoroethylene membranes and poly(tetrafluoroethylene‐co‐hexafluoropropylene) films

Two fully fluorinated polymers, poly(tetrafluoroethylene) (PTFE) membranes and poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP) films, were modified by graft copolymerization with monoacryloxyethyl phosphate (MAEP) in an aqueous solution at ambient temperature using gamma irradiation. The modified membranes were characterized by XPS, FTIR, and phosphate analysis. A correlation between peak heights in the FTIR PAS spectra and the overall grafting yield was found. Neither the surface coverage (as obtained from XPS multiplex scans) nor the overall grafting yield (as obtained from phosphate analysis) showed simple correlations on the monomer concentrations (20–40%) or the irradiation doses (25–150 kGy) within the ranges investigated. Similar surface coverage was achieved on the PTFE membranes and on the FEP films. In contrast, the overall grafting yields were significantly higher for the PTFE membranes than for the FEP films. The high porosity of the PTFE membranes is the most likely explanation for these differences in grafting. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2550–2556, 2002     

一种适合于教学的放射性同位素密度计

提出了一种适合于核工程与核技术专业本科生实验教学的放射性同位素密度计，简要介绍仪器系统的工作原理与组成。     

S7505颜色传感器及其在彩色密度计设计中的应用

介绍了S7505颜色传感器的特性,结合印刷颜色检测的特点给出了S7505传感器在彩色密度计设计中的使用方法及电路。实验证明,该电路在检测微弱光时能较好地满足测色需要,实现了印刷中三原色的检测,且在稳定性和精度上达到了设计要求。为S7505颜色传感器的使用提供了应用实例。     

A composite cylinder model for the prediction of residual stresses in gamma-titanium composites

An experimental study of the residual stress formation and evolution in γ-titanium-based composite material was completed for some important processing and heat treatment conditions. A concentric cylinder model based on Norton’s creep law with the coefficients replaced by new terms related to time and temperature was developed by a combination of viscoplasticity and thermoelastic analysis of concentric cylinder domains representative for the matrix and the fiber. The x-ray diffraction (XRD) technique was used to measure average residual stresses at the neighborhood of Saphikon fibers. The composite was fabricated by hot isostatic pressing. The residual stress at the matrix decreased as the temperature of the heat treatment increased up to an optimum value, after which the residual stress started to build up despite the increase in the annealing temperature. This phenomenon was depicted through the numerical model as well as in the XRD.