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Search Results: 1 - 10 of 87218 matches for " 胡宏 "
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关于二阶线性递归序列乘积的和式(英文)

南京师范大学学报(自然科学版) , 2006,
Abstract: 设{wn}是二阶线性递归序列,n为整数.根据二阶线性递归序列的定义和性质,给出了关于二阶线性递归序列乘积的和式sm,k,tm,k的定义,研究了关于二阶线性递归序列的和式sm,k,tm,k,得到了关于和式sm,k,tm,k的重要结论.本文的主要结论推广了melhamrs的二个结果.
Ag嵌入ZnO(10 0)表面的第一性原理研究
Ag Incorporation on ZnO(10 0) Surface: First Principles Study
 [PDF]

, 陈兰丽
Applied Physics (APP) , 2014, DOI: 10.12677/APP.2014.48018
Abstract:
基于密度泛函理论,采用第一性原理计算了Ag嵌入ZnO(10 0)面的几何结构和导电性以及电子结构,分析了Ag掺杂ZnO(10 0)面的表面结构弛豫和Ag嵌入ZnO (10 0)不同层的形成能情况。计算结果表明:和纯净ZnO(10 0)相比,Ag嵌入ZnO(10 0)受结构弛豫影响比较明显。同时发现,Ag嵌入ZnO(10 0)第一层的形成能最低,因此,Ag嵌入在第一层的情况最稳定,这表明Ag原子更容易集中在表面层,而不是占据体内位置。通过对纯净和掺杂体系的态密度图分析发现,Ag嵌入ZnO(10 0)表面表现为p型特征,有利于p型的制备。然而,Ag嵌入ZnO(10 0)第一层的离化能较高,不利于p型导电。
Based on the density function theory, we have performed first principles calculations of energetic stability and conductive properties and electronic structure of Ag incorporation on ZnO (10 0) surface, and after calculations, we have analyzed the relaxation of the structure and formation energy of Ag incorporation on ZnO (10 0) surface at different layers. Our results show that com-pared with pure ZnO (10 0), there is an obvious effect on the relaxation of the structure for Ag incorporation on ZnO (10 0) surface. Simultaneously, we found that the formation energy of the Ag incorporation on the first layer is the lowest in all cases. Therefore, Ag incorporation on the first layer is the most stable, which indicates that Ag atom prefers to collect in the surface layer instead of the bulk. And we found that the system for Ag incorporation on ZnO (10 0) surface demonstrates as p-type, which is in favors of fabricating p-type material. However, the ionization of Ag incorporation on ZnO (10 0) surface is much higher, which hinders the electronic ionize.

N-S共掺ZnO的电子结构和光学性质的第一性原理研究
First-Principles Investigation of Electronic Structure and Optical Properties in N-S Codoping ZnO
 [PDF]

, 陈兰丽
Applied Physics (APP) , 2014, DOI: 10.12677/APP.2014.44007
Abstract:

为了分析纯净ZnO和N元素的掺入对S掺杂ZnO的电子结构和光学性质的影响,基于密度泛函理论采用第一性原理计算方法,我们研究了各种复合体的缺陷形成能、离化能、态密度、导电率、介电函数和吸收系数。结果发现:3N-S共掺ZnO不仅能提高N受主溶解度,而且可以引起浅受主能级。这表明3N-S共掺能够得到高质量稳定p型ZnO。同时,随着N原子的增加,体系的离化能迅速降低,而体系的导电率增强。另外,通过对介电函数和吸收系数的计算,结果表明3N-S共掺ZnO在低能区有非常奇特的特性。希望不久我们的理论结果能够为实验提供理论依据。
To analyze the electronic structures and optical properties of pure-ZnO and N-S codoped ZnO, the defect formation and ionization energy, density of states, conductivity, dielectric constant and adsorption coefficient of varies complexes were calculated by the first-principles calculation methods based on Density Functional Theory (DFT). It is found that 3N-S codoping in ZnO not only enhances N acceptor solubility, but also leads to shallower acceptor energy, demonstrating that 3N-S codoping can obtain a high-quality and more stable p-type ZnO. Furthermore, as the incorporation of N atoms is increasing, the ionization energies of the complexes are sharply decreasing, and the conductivity of the system is enhanced. In addition, the calculation of the dielectric functions and adsorption spectrum shows that 3N-S codoped ZnO has interesting characteristic in the low-energy region. We expect that this theory study might be helpful for the experimental results.

N掺杂ZnO (100)表面对其电学性质的影响
Influence of N Doping on Electronic Properties of ZnO Surface
 [PDF]

, 陈兰丽
Advances in Condensed Matter Physics (CMP) , 2014, DOI: 10.12677/CMP.2014.34007
Abstract:
基于密度泛函理论的第一性原理计算了N掺杂ZnO (100)表面的形成能和电学性质。首先,我们分析了N掺杂ZnO (100)表面不同层时的结构弛豫情况,接着计算了N掺杂表面的形成能和电子结构。结果表明N掺杂后体系发生较大的晶格畸变。N掺杂块体ZnO的形成能比掺杂表面时的形成低。结果表明N很容易聚集在体内而不是表面。从N掺杂ZnO (100)表面的电子结构中得知,体系的费米能级向价带移动,这主要归因于N-p态,同时体系表现为p型特征。
A theory of formation energy and electronic properties of N doping ZnO (100) surface is proposed on the first principles based on density function theory. First, we have analyzed the relaxation of the structure of N doping ZnO (100) surface at different layers. Later, we have calculated the formation energy and electronic structure of N doping ZnO (100) surface. The results show that there is a large lattice distortion after N doping. And the formation energy is lowest in the bulk ZnO when N is doped in the bulk ZnO. The results show that N atom easily accumulates in the body instead on the surface layers. The calculated electronic structure shows that the Fermi level shifts into the valence band which is contributed by N-p states, and the system after doping demonstrates as p-type.
严重事故时蒸汽发生器传热管蠕变断裂风险评估
Quantitative Risk Assessment of Induced Steam Generator Tube Rupture in Severe Accident
 [PDF]

文超, 彭常
Nuclear Science and Technology (NST) , 2015, DOI: 10.12677/NST.2015.33008
Abstract:
严重事故时,一回路将会出现蒸汽自然循环冷凝回流现象;高温蒸汽不断进入热管段,波动管和蒸汽发生器传热管,最终可能导致蒸汽发生器传热管发生蠕变断裂失效。本文首先使用严重事故分析计算严重事故时传热管蠕变断裂参数和传热管断裂的概率。然后使用简化二级概率安全分析模型评估传热管蠕变断裂导致的大量早期释放频率。最后评价一回路卸压和恢复二次侧给水等严重事故缓解措施对防止蠕变断裂的有效性。可以发现在中压和高压的情况下,一回路卸压和恢复二次侧给水能够有效地防止传热管蠕变断裂,降低大量早期释放频率。
Under severe accident conditions with countercurrent natural circulating high temperature gas in the hot leg, surge line and steam generator tubes, SG tubes integrity could be threatened by creep rupture, particularly if cracks are present in the tube walls. In this study, the first step we performs thermal-hydraulic analysis to predict the creep rupture parameter of the tubes in severe accident. The next step we applies the creep rupture models to test the potential for the degraded SG to rupture before the hot leg. Then, the mean of the SG tube rupture probability was applied to estimate large early release frequency in simplified Level-2 PSA model, and the overall LERF (Large and Early Release Frequency) risk due to the Induced SGTR was calculated. In the final step, implementation of severe accident management guidance, such as the RCS depressurization and refilling to SG, is evaluated using PSA approach. It can be found that strategy of RCS depressuriza-tion and refilling to SG can mitigate the severe accident process under the condition of high and medium pressure, and reduce LERF effectively.
论跨国公司海外R&D投资对投资母国的影响
,
科技进步与对策 , 2008,
Abstract: 当跨国公司在海外扩张R&D活动的时候,跨国公司母国也面临着一些收益和成本问题。对于整个世界经济而言,R&D的国际化应该有助于加速创新过程。通过将更多国家创新体系紧密联系起来,R&D国际化为更多的知识和技术跨国界交流活动提供了便利。跨国公司R&D知识流动技术交流
数据网络及其发展

科技进步与对策 , 2000,
Abstract: 阐述了数据网络及其业务的发展趋向,IP业务的特点及其迅速增长的现状;探讨了ATM网络的优势;就IP技术的发展趋势:IP/ATM相结合和IPoverSDH两种技术模型作了比较。中国地质大学汉口分校,湖北武汉430030
丁基罗丹明B-硫氰酸盐-吐温-20体系高灵敏分光光度法测定微量硒的研究
李晓明,
分析化学 , 1989,
Abstract: 本文叙述了在吐温-20存在下用硫氰酸盐和丁基罗丹明B形成缔合型三元配合物测定微量硒(Ⅳ)。配合物的最大吸收波长为600nm,硒含量在0-5μg/25ml服从朗伯比尔定律,其ε600=6.4×105,重现性好,选择性高,是目前测定微量硒的一种高灵敏度的新的分光光度法,已用于水样中微量硒的测定。
铁炭微电解法降解布洛芬的研究
,
环境工程学报 , 2013,
Abstract: 药品和个人护理用品(PPCPs)是一类新兴有机污染物,对环境存在潜在的威胁,已引起国内外的广泛关注。以典型PPCPs物质-布洛芬(2-(4-异丁基苯基)丙酸)作为研究对象,采用铁炭微电解法对其进行降解处理,考察了影响布洛芬去除效率的主要因素,确定了各影响因素的最佳操作条件为:离子浓度0.8g/L,反应时间120min,铁屑用量1.5g/L,铁炭质量比2:1,pH为4.0;在此条件下,布洛芬去除率可达80%以上,布洛芬降解过程符合一级反应动力学。
电动与渗透反应格栅联合修复镉污染地下水实验

环境工程学报 , 2009,
Abstract: 通过实验方法研究了地下水中镉污染的电动力学修复效果,并分析其迁移变化特征。实验结果表明,电动修复中由于阴阳两极的氧化还原反应造成电极附近pH值产生明显变化,其中阳极附近的pH值由开始时的7.0逐渐变小到6.8,而阴极附近则相反,由开始时6.9逐渐增大到9.1,表明土壤的酸碱条件变化明显。Cd浓度变化反映在自然渗透条件下含水层中重金属污染物的迁移能力较弱,阳极附近地下水中Cd的去除率仅8.4%,而在电场作用下地下水中重金属的浓度发生明显变化,使得重金属污染物能在电极附近富集而被去除,当实验电场强度为0.5V/cm时,Cd在阴极的累积使得阳极附近地下水中去除率为72.9%,说明电动修复重金属Cd污染地下水的效果明显好于自然渗透状态。
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