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101.
GUAN Ai-hong WANG Yu-hua 《光电子快报》2008,4(1):42-44
The impacts of interband and intraband erosstalk are studied and compared experimentally. Results show that interband crosstalk can be removed with narrow-band filters and has no influence on signal. Intraband crosstalk will result in signal eye diagram close and BER increasing. When the polarization states of signal and crosstalk align, intraband crosstalk seriously decreases signal quality. But when they misalign, it has little influence. Coherent and incoherent crosstalk are studied experimentally. Results show that coherent crosstalk is less harmful to system performance than incoherent crosstalk. 相似文献
102.
Solar cells based on halide perovskites have recently been attractive due to their excellent power conversion efficiency (PCE), lower cost and simple manufacture. Here, a series of halide perovskites (ABX3: A = CH3NH3, CH(NH2)2, Cs, Rb; B = Pb, Sn, Ge; X = I, Br, Cl, F) were investigated by Density Functional Theory (DFT) calculations, together with Shockley-Queisser Maximum Solar Cell Efficiency (S-Q) and Spectroscopic Limited Maximum Efficiency (SLME) mathematical models. The results indicate that: the electronic structure of germanium perovskites bears a close similarity to that of lead perovskites with a small energy difference between the nonbonding orbital and antibonding orbitals, but with a large energy difference comparing with that of tin perovskites (0.6–1.7 eV for CsGeI3 at Z point of the Brillouin zone, 0.7–1.4 eV for CH3NH3PbI3 and 1.4–2.2 eV for CH3NH3SnI3 at R point of the Brillouin zone), which is attributable to the atomic level, where the 4s orbital energy of Ge (−11.5 eV) is close to the 6s orbital energy of Pb (−11.6 eV), but the 5s orbital energy of Sn (−10.1 eV) is significantly high. Therefore, germanium perovskites possess as high absorption coefficient around solar spectrum as lead perovskites, while tin perovskites only have low absorption coefficient, which makes the short-circuit current of CsGeI3 and CH3NH3PbI3 (0.017 Acm−2 and 0.016 Acm−2, simulated by SLME with a 200 nm absorber under AM1.5G) are higher than that of CH3NH3SnI3 (0.015 Acm−2) even if the bandgap of CsGeI3 and CH3NH3PbI3 (1.51 eV and 1.55 eV) are larger than that of CH3NH3SnI3 (1.21 eV). Meanwhile, the effective mass of electrons and holes are approximate for germanium perovskites and lead perovskites (0.14:0.19 for CsGeI3 and 0.12:0.12 for CH3NH3PbI3), indicating a balanced electrons and holes transport, whereas the electrons transport is much slower than the holes transport for tin perovskites due to the effective mass of electron is much larger than that of hole (0.17:0.04 for CH3NH3SnI3). As a result, the PCE of CsGeI3 (27.9%) and CH3NH3PbI3 (26.7%) is higher than that of CH3NH3SnI3 (19.9%). 相似文献
103.
104.
军用夜视仪器是高新技术装备,要求有好的可靠性做保证。通过对军用夜视仪器的可靠性现状分析,结合国外的先进经验,介绍了可靠性的研究方法。 相似文献
105.
A comparison of biological activities of a new soya biopeptide studied in an in vitro skin equivalent model and human volunteers 总被引:1,自引:1,他引:1
Andre-Frei V Perrier E Augustin C Damour O Bordat P Schumann K Förster T Waldmann-Laue M 《International journal of cosmetic science》1999,21(5):299-311
During aging, the epidermis and dermis become thin and an efficient anti-aging product should be able to stimulate the metabolism of senescent fibroblast and keratinocytes, in order to increase the quantity of extra-cellular matrix components such as collagen and glycosaminoglycans. A study performed in parallel on an in vitro skin equivalent model, and in vivo, with human volunteers, demonstrated the efficacy of one specific soya biopeptide for anti-aging properties. Such a biopeptide induces a significant increase of glycosaminoglycans synthesis in vitro and in vivo after a one-month treatment. We also showed that this new cosmetic ingredient is able to stimulate favourably the collagen synthesis in vitro and in vivo. This study provided the proof for anti-aging properties of a new soya biopeptide and also validated the skin equivalent model developed for this experimentation as an alternative method to animal or human testing for some cosmetic efficacy evaluations. 相似文献
106.
建国50周年的今天,我国的葡萄酒工业有了突破性的发展,从产量、工艺、设备、基地建设、科学文化等各方面的发展足以证明我国的葡萄酒工业会更加美好 相似文献
107.
勘测关键技术及其综合应用研究,系国家“八五”科技攻关208-02-05专题。该专题研究结合锦屏一、二级等工程,专业面广,应用性强,研究工作难度大,是当前水电工程地质勘探技术中的薄弱环节,是关系到前期工作进展和工程经济效益的重大课题。其研究内容包括:岩心定向技术、砂卵石层取心技术,地应力测试与分析新技术,岩体裂隙结构面的计算机处理系统、岩溶探测新技术、高分辨率工程地震勘探技术、3000系列测井仪的改 相似文献
108.
109.
Amal Al-Abri Yassine Jamoussi Naoufel Kraiem Zuhoor Al-Khanjari 《Telematics and Informatics》2017,34(6):878-893
There are a number of approaches to learning such as traditional approaches (teacher-centered) and collaborative approaches (learner-centered). Nowadays, the concepts of collaboration and social interactions are the major trends in education. Therefore, many researchers embrace these concepts to offer the educational field enhanced learning environments which are supported by communication and collaboration techniques. The adaptation causes the existence of varied approaches which are addressing the collaborative learning techniques. As a result, there is a need for a mechanism to study those approaches and highlight their eminence. The aim of this paper is to give a comprehensive overview about the state-of-art in collaborative learning, especially by integrating social media tools. To do so, the study adopts a classification framework based on four different views (subject, purpose, method, and tool). The framework has been used to compare ten collaborative e-learning approaches. The finding indicates the potential of all approaches in developing an online learning environment for remote collaborative learning despite the lack of fulfilling all the requirements highlighted in the four views. 相似文献
110.
Henrique Damasceno Vianna Jorge Luis Victória Barbosa 《Telematics and Informatics》2017,34(8):1419-1432
Non-communicable diseases burden is well-known and care for these diseases goes beyond patients’ engagement, extending to their family, friends, and acquaintances. The ability of social relations in alleviating the harmful effects of health risks is known as social support. Computing can be used to promote social support to enhance the care of non-communicable diseases. However, it is unclear how computing obtains such enhancement. This paper presents a systematic review, in the form of a mapping study, aiming to answer how computing enhances non-communicable diseases care by using social data and by promoting social support. It also looks for available computing models focused on social support promotion in non-communicable diseases care. The study was guided by a two-phase process review, resulting in 38 reviewed papers from journals, conferences, and chapters in the period from 2010 to 2016. In general, the reviewed papers focus on controlled trials, frameworks and systems, knowledge discovery, simulation models or social media usage analysis. Knowledge discovery was the predominant subject, followed by social media usage analysis, and frameworks and systems. 相似文献