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141.
在宽带网络的竞争中,服务商提供的网络速度,计费服务是否灵活多变,增值业务能否得到用户的认可,是竞争的焦点。本文提出了一种按流量计费和按时间计费均可的认证计费方式,同时可以为用户提供多种服务的软件架构,在小区接入服务和网络管理中,具有良好的扩展性和综合效益。 相似文献
142.
软件无线电是一种新兴技术,通过软件使多种业务、多种标准、多个频段与灵活的无线电系统的组合成为可重新配置和可重新编程的。介绍了软件无线电的概念及系统结构,并进一步讨论了现阶段软件无线电所面临的技术问题以及相应的实现方案。 相似文献
143.
Acoustic emission monitoring and numerical modeling
of FRP delamination in RC beams with non-rectangular cross-section 总被引:1,自引:1,他引:0
A case study concerning both numerical modeling and in-situ monitoring of a retrofitted RC beam with non-rectangular cross-section
is presented. Before retrofitting, non-destructive techniques, such as pull-out and impact tests, were used to estimate the
mechanical parameters of concrete. At the same time, a long-term monitoring with the Acoustic Emission (AE) technique was
carried out in order to investigate on creep effects and microcracking phenomena. Then, after a complete removal of the overload
and retrofitting with FRP sheets, an in-situ loading test was performed. At that stage, the AE technique was again profitably
used for the analysis of the cracking progression leading to FRP debonding. A numerical model of the structure is then proposed
in the framework of the FE discretization with mechanical parameters estimated according to an inverse analysis on the monitored
mechanical behavior of the structure before retrofitting. According to this model it is shown that, when the flexural inertia
of the retrofitted beam is considerably higher than that of the unrepaired beam, snap-back instabilities can take place. Finally,
considering the self-similarity between the acoustic emission phenomenon and seismicity, an analogy between the snap-back
instability of the FRP delamination and that occurring during fault growth is proposed.
Résumé Une étude de cas au sujet de modeler numérique et de surveiller in-situ d’un faisceau monté en rattrapage de RC avec la section transversale non-rectangulaire est présentée. Avant l’adaptation d’un faisceau, des techniques non destructives, telles que des essais à dégagement et à choc, ont été employées pour estimer les paramètres mécaniques du béton. En même temps, une surveillance à long terme avec la technique d’émission acoustique (AE) a été effectuée afin d’étudier sur des effets de fluage et des phénomènes de microfissuration. Puis, après un déplacement complet de la surcharge et l’adaptation ultérieure avec des feuilles de FRP, un essai in-situ de chargement a été réalisé. á cette étape, la technique d’AE a été encore profitablement employée pour l’analyse de la progression de fissures menant au décollement du FRP. On propose alors un modèle numérique de la structure dans le cadre de la discrétisation FE avec des paramètres mécaniques estimés selon une analyse inverse sur le comportement mécanique surveillé de la structure avant l’adaptation ultérieure. Selon ce modèle, on le démontre que, quand l’inertie flexural␣du faisceau monté en rattrapage est considérablement plus haute que cela de la structure non réparé, les instabilités de snap-back peuvent avoir lieu. En conclusion, vu l’auto similarité entre le phénomène d’émission et la séismicité acoustiques, on propose une analogie entre l’instabilité de snap-back du décollement de FRP et cela qui se produit pendant la croissance de défaut.相似文献
144.
Selim Erdoan Sema B Erdemolu Satlm Kaya 《Journal of the science of food and agriculture》2006,86(2):226-232
Fe, Zn, Mn and Cu levels in three Turkish legumes, kidney bean (Phaseolus vulgaris L.), lentil (Lens esculenta) and chickpea (Cicer arietinum), were determined by flame atomic absorption spectrometry. Dissolution conditions in the microwave‐assisted wet digestion method were studied by investigating several variables, including type of acid mixture, acid volume, digestion time, microwave power input and sample weight. Comparison with conventional wet acid digestion was also made. In order to check the element losses during digestion and the accuracy of the results, all tests were repeated after the addition of a spiked standard element solution to the legume sample. The microwave‐assisted digestion procedure optimised for kidney bean was adapted for lentil and chickpea. Fe, Zn, Mn and Cu concentrations (mg per 100 g sample) were determined in kidney bean as 6.27 ± 0.94, 2.23 ± 0.36, 1.64 ± 0.14 and 0.99 ± 0.19, in lentil as 8.24 ± 1.11, 2.46 ± 0.06, 1.17 ± 0.19 and 1.01 ± 0.28 and in chickpea as 6.00 ± 1.40, 2.21 ± 0.14, 1.60 ± 0.43 and 0.58 ± 0.18 respectively. Copyright © 2005 Society of Chemical Industry 相似文献
145.
Sook-Kyung Kim Diane K. Hancock Lili Wang Kenneth D. Cole Prasad T. Reddy 《Journal of research of the National Institute of Standards and Technology》2006,111(4):313-324
Ricin is an abundant protein from the castor bean plant Ricinus communis. Because of its high toxicity and the simplicity of producing mass quantities, ricin is considered a biological terrorism agent. We have characterized ricin extensively with a view to develop Reference Materials that could be used to test and calibrate detection devices. The characterization of ricin includes: 1) purity test of a commercial batch of ricin using electrophoresis in polyacrylamide gels, 2) biological activity assay by measuring its ability to inhibit protein synthesis, 3) quantitation of protein concentration by amino acid analysis, 4) detection of ricin by an immunoassay using a flow cytometer, and 5) detection of ricin genomic DNA by polymerase chain reaction using nine different primer sets. By implementing these five methods of characterization, we are in a position to develop a reference material for ricin. 相似文献
146.
P Yu 《Journal of the science of food and agriculture》2005,85(8):1268-1274
The effects of pressure toasting (100, 118 and 136 °C for 3, 7, 15 and 30 min) on potential protein nutritional value of faba beans were evaluated with the NRC 2001 dairy model, by determining undegraded (RUP) and degraded rumen protein (RDP), undegraded (RUST) and degraded rumen starch (RDST), truly absorbed undegraded protein (ARUP), microbial protein (MCPRDP) synthesized in the rumen from rumen‐available protein, truly absorbed rumen synthesized microbial protein (AMCP), truly absorbed rumen endogenous protein (AECP), total metabolizable protein (MP) in the small intestine, and the protein degradation balance (PDB). The treatments increased RUP, RUST, ARUP and MP (p < 0.001), and decreased RDP, RDST, MCPRDP and PDB (p < 0.001), the effects increasing with increasing temperature and time. The treatments increased (p < 0.001) ARUP without affecting AECP and AMCP, so that the net absorbable total MP in the small intestine was increased. The PDB was reduced (p < 0.001) but never became negative. These results indicated that potential microbial protein synthesis would not be impaired due to sufficient nitrogen in the rumen, but the high positive PDB values with most treatments, except 136 °C for 15 min (PDB 2.0 g kg?1 DM) indicated that there were large potential losses of nitrogen in the rumen, particularly for the control with a value of 88.9 g kg?1 dry matter. It is concluded that predicted potential protein degradation balance and total metabolizable protein supply from faba beans were improved by the treatments. Copyright © 2005 Society of Chemical Industry 相似文献
147.
霉变粉皮的微生物区系分析及防霉措施 总被引:5,自引:0,他引:5
从霉变粉皮的微生物区系分析阐述了防霉措施,抑制芽孢杆菌的最经济方法是控制粉皮的含水量,其次是添加防腐剂。 相似文献
148.
Johanna Dobereiner Segundo Urquiaga Robert M. Boddey 《Nutrient Cycling in Agroecosystems》1995,42(1-3):339-346
The development of sustainable agricultural systems for the tropics requires among other technologies, alternatives for nitrogen fertilizers which are often limited in availability for financial reasons and also represent a major source of groundwater and air pollution. There are many new alternatives for the development of agricultural systems which make use of biological processes in soil. Biological nitrogen fixation (BNF), that is, the biological conversion of atmospheric dinitrogen into mineral N, is the most important alternative among them. Examples are given of the impact of various technologies used in Brazil. Soybean, introduced into the country 30 years ago, is now the second most important export crop, reaching 24 million tons annually with no N fertilizer application. Consequently, Brazil today is the country in the world which uses the lowest amounts of nitrogen fertilizers in relation to phosphate. Alternatives for crop rotations and pastures are also discussed. Possibilities of expanding BNF to cereals and other non-legume crops are gaining new credibility due to the identification of endophytic associations with diazotropic bacteria. The definite proof of substantial BNF in sugar cane with N balance and15N methods in certain genotypes selected under low N fertilizer applications opens up new alternatives for sustainable agriculture and will be the key to viable bio-fuel programmes. 相似文献
149.
Khalid S. Al-Numair Saif Eldein B. Ahmed Abdullah H. Al-Assaf Mohammed S. Alamri 《Food chemistry》2009
Two faba bean (Hudieba-72 and Bsabir) and three white bean (Serge, Giza and RO21) cultivars were sprouted for 6 days. The sprouted grains were dried and milled. Phytic acid and polyphenols contents and hydrochloric acid (HCl) extractability of minerals from the malt flours were determined at intervals of 2 days during sprouting. Phytic acid and polyphenols contents decreased significantly (P ? 0.01) with increase in sprouting time with concomitant increase in HCl extractable major and trace minerals. The contents of both major and trace minerals were slightly increased with sprouting time. When faba bean seeds were sprouted for 6 days, Bsabir had higher extractable Ca, while Hudieba-72 had higher P, whereas Fe and Mn recorded high level in Hudieba-72. When white bean seeds were sprouted for 6 days, RO21 cultivar had higher extractable Ca, while Giza-3 cultivar had higher P, whereas Fe and Mn recorded high levels in Serge and RO21 cultivars, respectively. There was a good correlation between phytate and polyphenols reduction and increase in extractable minerals with increase in sprouting time for all cultivars. 相似文献
150.