摘要：Numerous smart card based authentication protocols have been proposed to provide strong system security and robust individual privacy for communication between parties these days. Nevertheless, most of them do not provide formal analysis proof, and the security robustness is doubtful. Chang and Cheng(2011) proposed an efficient remote authentication protocol with smart cards and claimed that their proposed protocol could support secure communication in a multi-server environment. Unfortunately, there are opportunities for security enhancement in current schemes. In this paper, we identify the major weakness, i.e., session key disclosure, of a recently published protocol. We consequently propose a novel authentication scheme for a multi-server environment and give formal analysis proofs for security guarantees.

摘要：We investigated the structural behavior and bearing capacity of system *** research showed that the critical load of a system scaffold structure without diagonal braces is similar to that of a door-shaped steel scaffold *** stiffness between vertical props in system scaffolds can be defined based on a comparison between analytical and experimental *** the number of scaffold stories increases,the critical loads of system scaffolds *** braces markedly enhance the critical load of system *** coupling joint position between vertical props should be kept away from story-to-story joints to prevent a reduction in critical *** critical load of a system scaffold decreases as the quantity of extended vertical props at the bottom of the structure increases.A large Christmas tree set up by system scaffolds under various loads was used as an example for analysis and to check the design of system scaffolds.

摘要：随着化石燃料燃烧导致的二氧化碳排放不断加剧气候变化,且化石燃料储量日益减少,寻求可再生能源已成为一项紧迫的任务.其中,藻类衍生可持续燃料因具有成本优势和可运输性,在解决全球能源危机方面展现出广阔前景,备受关注.利用化学转化技术从微藻中提取脂质,并通过酯交换反应可以将其转化为脂肪酸甲酯,是生产绿色生物燃料的有效途径.这一过程涉及游离脂肪酸、磷脂和甘油三酯的提取,并且生产过程能耗低,成为满足日益增长的能源需求的一种理想解决方案.本文综述了微藻脂质提取和酯交换制备生物燃料的相关研究进展.首先,介绍了微藻脂质的提取方法,包括溶剂提取法、索氏提取法、布利格和戴耶法、超临界二氧化碳提取以及离子液体溶剂法等,并分析了各方法的优缺点.随后,重点阐述了酯交换技术在微藻脂质转化中的应用,包括酸碱催化、酶催化以及原位酯交换反应等,并探讨了这些技术的反应机理、催化剂选择、反应器设计以及生物油生产工艺等方面的研究进展.通过综述上述研究进展,为微藻脂质的生产和应用提供了理论指导.研究表明,通过优化催化剂种类、反应条件以及提取方法,可以有效提高微藻脂质的转化效率和生物油品质.同时,本文也指出了当前微藻脂质生产中面临的挑战,如微藻栽培和生长条件优化、高效转化技术的开发等.随着可持续能源日益受到重视,微藻脂质作为一种可再生能源具有巨大的发展潜力.未来研究应进一步关注微藻的规模化栽培、生长条件优化以及高效转化技术的研发,以提高微藻脂质的产量和品质.同时,应进一步推动和实现微藻生物燃料的实际应用,从而为应对气候变化和能源危机提供有效的解决方案.