Causal consistency is one of the important projects to ensure data consistency in distributed storage.The current research focuses on causal consistency including optimization of clock method,design of the protocol and the optimization of operation transaction sequence.In the actual cloud environment,in addition to clock skew and query amplification,there are also insecure factors such as Trojans and untrusted third parties,which will destroy the causal consistency metadata stored by users,and the consistency of user’s operating results,even affect the availability of the storage environment.From the perspective of performance improvement and security in distributed storage,the clock synchronization,data replications,analysis and design of server protocol,related research progress of the serialization of operational affairs were introduced combined with consensus mechanisms such as blockchain.At the same time,their principlest,advantages,limitations,and different utilities in terms of security constraints were discussed,and then the future development trends and follow-up research directions were point out at last,which would provide a reference and help for the research in this field.

In order to solve the problem of metadata propagation overhead,operation delay and remote update visibility latency in the current causal consistency model,a causal consistency model for distributed data stores based on the shared graph and partial replication strategy was proposed.This model was based on the topology of the shared graph,and each data center stored an arbitrary subset of the data.At the same time,the global stabilization strategy combining shared stable vector and hybrid logical clocks was proposed to provide data consistency guarantees on the premise of ensuring causality.The theoretical analysis and experimental results show that the proposed model can effectively balance the remote update visibility and the metadata overhead compared with the existing models while reducing the operation delay.

<正>明代从朱元璋时就大量出现官僚腐败现象,宣告了明代教育的破产。虽然腐败的现象非常普遍,但明代的政权却长达270余年。这种奇怪的背反,表明了教育史的研究,不能停留在历史现象的叙述上,而应该去追溯这些现象背后的意义和原因。第一,过于单一的办学目标,限制了学校教育的功能,也限制了办理学校的灵活性。导源于"诱以利禄之途"的习惯思想,

<正>同唐宋时代相比,明代的国子监在办学形式上趋于简单化。一方面,从宋以来逐渐模糊的国子学与太学之间的界限,在明代被完全取消,过去国子学、太学、四门学的教育职责由作为具体教育机构的国子监独立承担;另一方面,算学、律学、书学等被排除在国子监之外。因此,在明代",国子监"与‘"太学"在指称的对象上完全一致,从而使国子监由唐宋时代的中央学校管理机构转化为比较单一的教育机构。

随着社会经济的发展,特许经营这一分销方式以其独特的经营优势取得了世人瞩目的成功。近几年来,特许经营以其快速的融资方式和共赢的盈利理念为越来越多的商业人士所重视。但是,由于特许经营方式在中国市场历史较短,很多问题屡见不鲜。本文通过对我国特许经营中特许方和受许方的问题分析,探讨特许经营发展中面临的新问题的实质以及解决这些问题的对策。

明代朝觐考察制度是明代统治者针对地方官员的一项重要的人事管理制度,也是明代官吏考核制度的一个重要组成部分。它建制完备,贯穿了明代的整个历史进程,其在中国古代官吏考核制度发展史上具有承前启后、继往开来的重要地位和作用。这一制度的制定和实施,不仅直接关系到各级地方官吏的切身利益和各项政令的下达实施,同时也促进了明代当时吏治的整饬和官员队伍体系的更新换代,并为其后的清代所效法。但明中叶以后,由于吏治的日趋腐败和制度的逐步僵化,使得朝觐考察过程中考察不公、处罚不严等诸多弊端逐渐显现,直至明亡。