Hydrothermal synthesis and photoluminescence behavior of CeO<Subscript>2</Subscript> nanowires with the aid of surfactant PVP

Well-crystalline CeO₂ nanowires were prepared via a surfactant-assisted hydrothermal process. Reaction temperature and reaction time were changed for the determination of optimal synthesis parameters. The as-obtained products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and field emission scanning electron microscopy (FESEM). The results show that single crystal CeO₂ nanowires with high yield and good uniformity can be obtained hydrothermally at 180°C for 12 h with the aid of 2.0 g surfactant (polyvinyl pyrrolidone, PVP). The role of PVP was then discussed and a possible growth mechanism was proposed. Moreover, room temperature photoluminescence (PL) spectra were obtained for these CeO₂ nanowires, which are believed to be related to the abundant defects in these nanostructures.     

汽车制动性系统检测常见问题及解决措施

汽车制动性能的好坏,直接关系到行车安全,它是汽车安全行驶中的重点项目之一.对其进行及时准确的检测是保证道路交通安全的必要手段.文章针对路试检验汽车制动性能的常见问题进行了探讨.     

地源热泵系统的推广优势及存在的问题

地源热泵系统为一种能提供新型的清洁可再生能源的环保系统.简要介绍了地源热泵系统的定义、类型、组成及工作原理,对比传统的空气源热泵的优缺点,详细阐述了地源热泵系统的众多优势,并指出了其在发展和推广应用中所面临的多方面问题,对地源热泵系统的推广应用提出了一些建议.随着技术的不断完善,地源热泵系统必然有着很好的发展前景.     

Improved spectrum sharing algorithm based on feedback control information in cognitive radio networks

In order to avoid the system performance deterioration caused by the wireless fading channel and imperfect channel estimation in cognitive radio networks, the spectrum sharing problem with the consideration of feedback control information from the primary user is analyzed. An improved spectrum sharing algorithm based on the combination of the feedback control information and the optimization algorithm is proposed. The relaxation method is used to achieve the approximate spectrum sharing model, and the spectrum sharing strategy that satisfies the individual outage probability constraints can be obtained iteratively with the observed outage probability. Simulation results show that the proposed spectrum sharing algorithm can achieve the spectrum sharing strategy that satisfies the outage probability constraints and reduce the average outage probability without causing maximum transmission rate reduction of the secondary user.     

浅谈沥青路面常见病害成因及防治对策

文章介绍了沥青路面常见病害的形式及其成因,并简要探讨了病害防治的对策。     

Preparation of superhydrophobic silver nano coatings with feather-like structures by electroless galvanic deposition

Superhydrophobic silver nanocoatings with feather-like morphology are fabricated on copper substrates by electroless galvanic deposition. The coating exhibit superhydrophobicity with a contact angle of 156.4° and glide angle of 4° without any further surface modification. Scanning electron microscope (SEM), X-ray diffraction (XRD) and contact angle measurements are used to investigate the morphology, crystal structure and superhydrophobicity, respectively, of the coatings. The coatings exhibit high thermal stability; their water contact angle did not change when the coatings were heated to 200°C for 2 h. The mechanism of superhydrophobicity of the silver coating is discussed based on the work of Amirfazli, Wenzel and Cassie.     

高校图书馆借阅超期的原因与对策

当前高校图书馆借阅超期较为普遍,通过问卷调查得知读者的借阅超期大多无恶意行为。针对这种情况以及高校图书馆自身的条件和特点,实施"告知服务"可减少借阅超期行为,以此提高图书的利用率。     

Anonymous multipath routing protocol based on secret sharing in mobile ad hoc networks

Because the intrinsic characteristics of mobile ad hoc networks(MANETs) cause several vulnerabilities,anonymous routing protocols attract much more attention in secure mobile ad hoc networks for the purposes of security and privacy concerns.Until recently,lots of anonymous routing protocols have been proposed.However,most of them are single path or use one path at a time,and the multipath schemes can not thwart both the passive attacks and active attacks simultaneously.Thus an anonymous multipath routing protocol based on secret sharing is proposed.The protocol provides identity anonymity,location anonymity,data and traffic anonymity by employing cryptograph technology and secret sharing in MANET communication process.Meanwhile,a hash function is introduced to detect active attacks in the data transmission process.The protocol can effectively thwart various passive attacks and reduce the successful probability of active attacks(such as interception and physical destroy attacks).Simulation results show that the proposed scheme provides a reasonably good level of network security and performance.     

论水泥搅拌桩在高速公路软基处理中的施工工艺

介绍了采用水泥搅拌桩处理祁临高速公路临汾北环段第四合同段软质地基的施工方法、施工要求及质量控制。     

基于GO-FLOW法的苹果冷链物流系统安全性评价

应用系统可靠性理论,利用GO-FLOW方法对苹果冷链物流系统进行安全性分析和风险评价,进行GO-FLOW程序运算,分析系统各环节的可靠性和故障率,找出了影响系统安全性的关键环节并提出了解决思路.