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排序方式: 共有443条查询结果,搜索用时 15 毫秒
51.
M. Din G.N. Tiwari M.K. Ghosal N.S.L. Srivastava Md. Imran Khan M.S. Sodha 《国际能源研究杂志》2003,27(1):79-92
In this communication, thermal model of a greenhouse has been developed by incorporating the effect of water wall in the north side. Various temperatures, namely plant, water wall and room temperatures as a function of climatic and design parameters have been obtained by solving coupled single-order differential equation using Runge–Kutta method. Numerical methods have been carried out for a typical day of winter for Delhi condition. It has been observed that there is significant effect in the plant, room air and water temperatures due to change in fraction of solar radiation incident on north wall (Fn) and heat capacity of water wall. Experimental validation of the proposed model for a greenhouse with brick north wall has also been carried out. It has been observed that there is a fair agreement between experimental and theoretical values. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
52.
The antioxidant properties and the effect on nitric oxide (NO) production, in lipopolysaccharide-activated macrophages, of 12 traditional vegetables of the Malaysian Malays, including Pithecellobium confertum, Averrhoa bilimbi, Portulaca oleracea, Solanum torvum, Solanum nigrum, Persicaria tenella, Cosmos caudatus, Pandanus amaryllifolius, Curcuma mangga, Ocimum basilicum, Anacardium occidentale and Melicope ptelefolia, were investigated. Antioxidant activity of the methanolic extracts was evaluated by measuring the production of hydroperoxide and its degradation product (malonaldehyde) resulting from linoleic acid oxidation using ferric thiocyanate and thiobarbituric acid methods, respectively. Radical-scavenging potential was also evaluated using the 1,1-diphenyl-2-picrylhydrazyl radical. Griess assay was used to assess NO-inhibitory activity of the extracts. All species, except P. confertum, S. torvum and P. amaryllifolius, showed antioxidant activity. M. ptelefolia, P. oleracea and P. tenella showed in vitro activity on NO inhibition in murine peritoneal macrophages, whereas other plants showed no significant activity. 相似文献
53.
哈伯特储量发现模型是以勘探历史为背景的统计学模型,该模型不仅考虑了以往的发现率,而且考虑了当前的发现率,估算的最终或剩余储量更为准确,可靠,应用此模型对川南P1最终地质储量估算结果表明,在这个区带天然气最终可探明数百亿立方米,目前还有近七分之一的剩余地质储量尚待发现。 相似文献
54.
Ali Özvan İsmail Dinçer Altay Acar Burcu Özvan 《Bulletin of Engineering Geology and the Environment》2014,73(3):801-813
Surface roughness is one of the most important parameters governing the shear strength of rock discontinuities. Roughness types may vary based on genesis, physico-mechanical, and mineralogical properties of rocks. In this study, granite samples representing three different weathering degrees were selected to evaluate the effects of surface roughness and weathering degree on shear strength. To this aim, we determined the profile roughness coefficient (PRC), profile roughness angle (PRA), and joint roughness coefficient (JRC) for the selected fresh and weathered granite joint samples. Values of PRC were in the range of about 1.043–1.073, and PRA and JRC varied in the ranges of 16.67–21.45 and 12–18, respectively. Weathering led to the increment of joint surface roughness of the selected granitic joints due to the higher resistance of quartz crystals in the weathered matrix. However, the increment in surface roughness did not result in an increase in the shear strength. On the contrary, the shear strength of discontinuities dramatically decreased. 相似文献
55.
Khairayu Badron Ahmad Fadzil Ismail Md Rafiqul Islam Khaizuran Abdullah Jafri Din Abdul Rahman Tharek 《International Journal of Satellite Communications and Networking》2015,33(1):57-67
Radio wave propagation plays a very important part in the design and eventually dictates performance of space communication systems. Over time, the requirements of satellite communication have grown extensively where higher capacity communications systems are needed. Escalating demands of microwave and millimetre wave communications are causing frequency spectrum congestion. Hence, existing and future satellite system operators are planning to employ frequency bands well above 10 GHz. The challenge in operating at such high frequencies for communication purposes is that there exists stronger electromagnetic interaction between the radio signals and atmospheric hydrometeors. Such instances will degrade the performance of such high frequency satellite communication systems. The development of a revised model for a better‐improved rain fade prediction of signal propagations in tropical region is considered very important. Researchers and engineers can employ the model to accurately plan the future high frequencies satellite services. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
56.
57.
Parab HJ Huang JH Lai TC Jan YH Liu RS Wang JL Hsiao M Chen CH Hwu YK Tsai DP Chuang SY Pang JH 《Nanotechnology》2011,22(39):395706
The feasibility of using gold nanoparticles (AuNPs) for biomedical applications has led to considerable interest in the development of novel synthetic protocols and surface modification strategies for AuNPs to produce biocompatible molecular probes. This investigation is, to our knowledge, the first to elucidate the synthesis and characterization of sodium hexametaphosphate (HMP)-stabilized gold nanoparticles (Au-HMP) in an aqueous medium. The role of HMP, a food additive, as a polymeric stabilizing and protecting agent for AuNPs is elucidated. The surface modification of Au-HMP nanoparticles was carried out using polyethylene glycol and transferrin to produce molecular probes for possible clinical applications. In vitro cell viability studies performed using as-synthesized Au-HMP nanoparticles and their surface-modified counterparts reveal the biocompatibility of the nanoparticles. The transferrin-conjugated nanoparticles have significantly higher cellular uptake in J5 cells (liver cancer cells) than control cells (oral mucosa fibroblast cells), as determined by inductively coupled plasma mass spectrometry. This study demonstrates the possibility of using an inexpensive and non-toxic food additive, HMP, as a stabilizer in the large-scale generation of biocompatible and monodispersed AuNPs, which may have future diagnostic and therapeutic applications. 相似文献
58.
As networks grow in size and complexity, both the probability and the impact of failures increase. The pre-allocated backup
bandwidth cannot provide 100% protection guarantee when multiple failures occur in a network. In this article, we focus on
how to recover the protecting capabilities of FIPP (Failure-independent path-protecting) p-cycles against the subsequent links
failure on WDM networks, after recovering the working paths affected by the failure of link. Two recovering policies are designed
to recover the protecting capabilities of the FIPP p-cycles if possible, unless there is no sufficient network resource. They
are Cycle Recovery Policy and Path Recovery Policy. In addition, a Cycle Adjust algorithm is proposed and used to recover the affected cycles. The simulation results of the proposed methods are also given. 相似文献
59.
Yuan Hsing Fu Ai Qun Liu Wei Ming Zhu Xu Ming Zhang Din Ping Tsai Jing Bo Zhang Ting Mei Ji Fang Tao Hong Chen Guo Xin Hai Zhang Jing Hua Teng Nikolay I. Zheludev Guo Qiang Lo Dim Lee Kwong 《Advanced functional materials》2011,21(18):3589-3594
A micromachined reconfigurable metamaterial is presented, whose unit cell consists of a pair of asymmetric split‐ring resonators (ASRRs); one is fixed to the substrate while the other is patterned on a movable frame. The reconfigurable metamaterial and the supporting structures (e.g., microactuators, anchors, supporting frames, etc.) are fabricated on a silicon‐on‐insulator wafer using deep reactive‐ion etching (DRIE). By adjusting the distance between the two ASRRs, the strength of dipole–dipole coupling can be tuned continuously using the micromachined actuators and this enables tailoring of the electromagnetic response. The reconfiguration of unit cells endows the micromachined reconfigurable metamaterials with unique merits such as electromagnetic response under normal incidence and wide tuning of resonant frequency (measured as 31% and 22% for transverse electric polarization and transverse magnetic polarization, respectively). The reconfiguration could also allow switching between the polarization‐dependent and polarization‐independent states. With these features, the micromachined reconfigurable metamaterials may find potential applications in transformation optics devices, sensors, intelligent detectors, tunable frequency‐selective surfaces, and spectral filters. 相似文献
60.
Din KS 《The Science of the total environment》2011,409(24):5301-5304
The concentration of 210Po was determined in different foodstuffs of plant origin purchased from markets in Qena City, Upper Egypt. Measurement of 210Po has been carried out using alpha spectrometry technique in different food categories such as vegetables, fruits, cereals beverages and herbs. The general range of 210Po activity levels ranged widely from < 0.010-18.6 ± 0.910 mBq g− 1, with minimum being in cereal samples and maximum being in beverage samples. Tea samples recorded highest activity concentrations of 210Po with lowest value of 10 ± 0.54 mBq g−1 for Crown tea and highest value of 18.6 ± 0.910 mBq g−1 for El maabad tea. The daily intake of 210Po from food consumption reveals that vegetables are the biggest contributors, while beverages are the lowest. The effective ingestion dose has been estimated for Qena City residents and it was found in the range 0.008-38.3 μSv y−1. 相似文献