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131.
132.
Fazal-ur-Rehman M.I. Al-Jarallah F. Abu-Jarad M.A. Qureshi 《Radiation measurements》2005,40(2-6):595-600
A set of five 241Am–Be neutron sources are utilized in research and teaching at King Fahd University of Petroleum and Minerals (KFUPM). Three of these sources have an activity of 16 Ci each and the other two are of 5 Ci each. A well-shielded storage area was designed for these sources. The aim of the study is to check the effectiveness of shielding of the KFUPM neutron source storage area. Poly allyl diglycol carbonate (PADC) Nuclear track detectors (NTDs) based fast and thermal neutron area passive dosimeters have been utilized side by side for 33 days to assess accumulated low ambient dose equivalents of fast and thermal neutrons at 30 different locations around the source storage area and adjacent rooms. Fast neutron measurements have been carried out using bare NTDs, which register fast neutrons through recoils of protons, in the detector material. NTDs were mounted with lithium tetra borate (Li2B4O7) converters on their surfaces for thermal neutron detection via and nuclear reactions. The calibration factors of NTD both for fast and thermal neutron area passive dosimeters were determined using thermoluminescent dosimeters (TLD) with and without a polyethylene moderator. The calibration factors for fast and thermal neutron area passive dosimeters were found to be 1.33 proton tracks and 31.5 alpha tracks , respectively. The results show variations of accumulated dose with the locations around the storage area. The fast neutron dose equivalents rates varied from as low as up to whereas those for thermal neutron ranged from as low as up to . The study indicates that the area passive neutron dosimeter was able to detect dose rates as low as 7 and from accumulated dose for thermal and fast neutrons, respectively, which were not possible to detect with the available active neutron dosimeters. 相似文献
133.
利用二阶行列式的几何意义是有向面积及积分因子的存在性给Green公式一个新的证明.尽管技术上走得远了些,但从概念上揭示了Green公式异常简明的几何意义,即Green公式只是面积的两种不同表达方式.同时这也蕴含了一个更深刻的哲学含义,即一般性隐含于特殊性(或特例)之中. 相似文献
134.
The distortion property of hyperbolic area of planar quasiconformal mappings is studied in this paper.In the case of radial quasiconformal mappings and angular deformed quasiconformal mappings their hyperbolic area distortions are estimated quite sharply.The result can be applied to judge whether the hyperbolic area of a planar subset is explodable. 相似文献
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区间数可能度的二维定义 总被引:1,自引:0,他引:1
利用二维空间的面积,提出了一个新的区间数可能度的定义,并给出了简单实用的计算公式和证明了相关的性质,最后,通过实例说明了该定义的实用性. 相似文献
138.
Enzyme activity of commercial glucose oxidase was enhanced after purification through a strong anionic exchange resin. In order to get a better insight into this phenomenon, surface pressure–area (π–A) isotherms and surface pressure–time (π–t) isotherms was used to study the interaction and the absorption at different pH values of the subphases between octadecylamine and glucose oxidase purified by a styrene system quaternary ammonium type strongly basic anionic exchange resin. Circular dichroism (CD), electrophoresis and enzyme activity measurements were conducted to study these phenomena. A preliminary hypothesis has been suggested to explain why the enzyme activity of purified glucose oxidase was higher than that of the commercial one. 相似文献
139.
The aim of this paper is to study the local and asymptotic behavior of Brownian motion on simply connected nilpotent Lie groups. We carry over a qualitative version of the Erdös-Rényi law of large numbers for Brownian motion to simply connected step 2-nilpotent Lie groups. The method applied gives rise to a proof for qualitative results concerning the modulus of continuity of Brownian motion on simply connected step 3-resp. step 2-nilpotent Lie groups without using the Ventsel-Freidlin theory as in Baldi. 相似文献
140.
Precise control and knowledge of surface structures are essential inorder to meet the requirements of today's and future materials. One possiblegrowth technique capable of meeting the requirements is atomic layer epitaxy(ALE). ALE is based on sequentially applied saturated gas-solid reactions,which provide the means for adsorption controlled material deposition atatomic layer level. In this paper the potentiality of the use of porousmaterials in a detailed study of adsorption controlled growth is discussed.At the same time the study promotes the application of adsorption controlledmaterials processing for advanced catalysts manufacturing. 相似文献