Implementing Discretionary Access Control with Time Character in Linux and Performance Analysis

DAC （Discretionary Access Control Policy） is access control based on ownership relations between subject and object, the subject can discretionarily decide on that who, by what methods, can access his owns object. In this paper, the system time is looked as a basic secure element. The DAC_T （Discretionary Access Control Policy with Time Character） is presented and formalized. The DAC_T resolves that the subject can discretionarily decide that who, on when, can access his owns objects. And then the DAC_T is implemented on Linux based on GFAC （General Framework for Access Control）, and the algorithm is put forward. Finally, the performance analysis for the DAC T Linux is carried out. It is proved that the DAC T Linux not only can realize time constraints between subject and object but also can still be accepted by us though its performance have been decreased.

Pass/Fail and Discretionary Grading: A Snapshot of Their Influences on Learning

This article provides a snapshot of pass/fail and discretionary grading approaches, highlighting the advantages and disadvantages of each. Norm-referenced and criterion-referenced grading practices and their associations with learning are identified. A brief historical backdrop illustrates how grading practices have evolved. The inherent subjectivity of grading is emphasized. Pass/fail grading supports intrinsic motivation and self-direction, but limits opportunities for recognizing excelling students. Discretionary grading, which includes letter (F- to A+) and numeric (0% to 100%) representations, supports extrinsic motivation and self-improvement, but promotes unhealthy competition. Both approaches have merit and can effectively measure student achievement in nursing education programs.

Discretionary Power in the Course of Granting Graduate Degree in America and Its Enlightenments

Graduate education is the key support to the national competitive and technological levels. Therefore, the system of granting graduate degree was clearly guaranteed in the national level. For example, there are Education Law and Higher Education Law in China; the people＇ s education right is protected by federal constitution in the United States, and also universities or institutes have their own charters to claim the relative rights. The system safeguards the legitimacy of degree granting, but also gives a considerable discretionary power to the granting units who can grant or cancel the degree.

Managing Discretionary Services: A Review and Research Opportunities

Discretionary services typically refer to professional work and complex service work by physicians,software developers,web designers,lawyers,or financial analysts,where there are no standard working processes and customer perceived quality of service increases with the time spent on it.Recently,research on these services,especially the corresponding speed-quality tradeoff problem,has gained more and more attention.This paper reviews both the analytical models and the empirical studies in this area,highlighting their contributions and pointing out potential directions for future research.

Optimal Policies for Inventory Systems with Discretionary Sales,Random Yield and Lost Sales

We determine replenishment and sales decisions jointly for an inventory system with random demand, lost sales and random yield. Demands in consecutive periods are independent random variables and their distributions are known. We incorporate discretionary sales, when inventory may be set aside to satisfy future demand even if some present demand may be lost. Our objective is to minimize the total discounted cost over the problem horizon by choosing an optimal replenishment and discretionary sales policy. We obtain the structure of the optimal replenishment and discretionary sales policy and show that the optimal policy for finite horizon problem converges to that of the infinite horizon problem. Moreover, we compare the optimal policy under random yield with that under certain yield, and show that the optimal order quantity （sales quantity） under random yield is more （less） than that under certain yield.

A Logic-Based Safety Analysis Algorithm for Discretionary Access Control

For the issue of the discretionary access control（DAC） model safety analysis,a logic method is proposed.This method takes the GD model as the classic DAC model and Prolog as the basic language to describe system states and state transfer rules.A general program based on this logic method is proposed for DAC safety analysis,but this program may never be terminal for some safety analysis goal.The safety analysis algorithm is achieved by simplifying the general program according to the property of the DAC model state transfer rules.This safety analysis algorithm is easier to understand and implement than the previous algorithms and its time complexity is O（N＋M＋T）,in which N,M,and T are the numbers of the rights with copy flag,the policies for right transferring,and the policies for right permitting,respectively.

THE OPTIMIZATION PATH OF THE DISCRETIONARY REQUIREMENTS OF CHINA'S ENVIRONMENTAL LITIGATION INJUNCTION

The 19th National Congress of the Communist Party of China pointed out that the construction of ecological civilization is a millennium plan for the sustainable development of the Chinese nation.Constructing ecological civilization and adhering to green development is the basic strategy of adhering to and developing socialism with Chinese characteristics in the new era.In the litigation system of China,it is the behavior preservation system that corresponds to the litigation injunction.In civil litigation,the main legal basis for the preservation of civil action is the part on the preservation of acts in the provisions of article 100 of the Code of Civil Procedure,which refers to the obstacles to the performance of future judgments or the further infringement caused to the parties.The court shall,on the application of a party or in accordance with its authority,order the other party to make certain acts or prohibit certain acts.The injunction of environmental litigation is an important preventive measure to give full play to the concept of plain environmental justice.

“国家在战争或武装冲突中使用核武器的合法性问题咨询意见案”述评

针对世界卫生组织要求就"国家在战争或武装冲突中使用核武器的合法性问题"发表咨询意见的请求,国际法院以"不属于其职权范围"为由,在其司法实践中第一次决定拒绝发表咨询意见。在分析国际法院推理的基础上,本文指出,国际法院的决定尽管有其不足,但它将决定建立在"联合国体系"和"专业性原则"这两个规范性概念的基础上,目的在于维护国际法体系的统一性;基于同样原因,国际法院没有将隐含权力理论适用于本案。

办公自动化系统安全模型研究

给出了办公自动化系统的技术特征和安全需求,就相关的几种主要安全模型进行了分析对比,得出结论:RBAC安全模型最适合办公自动化系统的安全访问控制。

An Efficient Role and Object Based Access Control Model Implemented in a PDM System

An effective and reliable access control is crucial to a PDM system.This article has discussed the commonly used access control models,analyzed their advantages and disadvantages,and proposed a new Role and Object based access control model that suits the particular needs of a PDM system.The new model has been implemented in a commercial PDM system,which has demonstrated enhanced flexibility and convenience.

Stock transferability,the managerial learning effect and corporate innovation

This paper considers stock halts to study the impact of stock liquidity loss on the managerial learning effect based on stock prices.We examine stock halts’impact on corporate innovation and find that discretionary halts hinder innovation.We also find that discretionary halts reduce information quality and increase financial constraints and agent costs.Cross-sectional tests show that this negative impact is more pronounced in samples with high shareholding ratios by large shareholders,institutional investors and private firms.The results indicate that the loss of non-institutional stock trading rights,represented by discretionary stock halts,affects revelatory price efficiency in the secondary market,hinders managers’learning effect and affects enterprises’production and operation decisions.These findings have policy implications for stock circulation-right protection and Chinese capital-market reform.

Modelling lane-changing execution behaviour in a connected environment:A grouped random parameters with heterogeneity-in-means approach

Lane-changing is performed either to follow the route to a planned destination(i.e.,mandatory lane-changing)or to achieve better driving conditions(i.e.,discretionary lane-changing).A connected environment is expected to assist during lane-changing manoeuvres,but it is not known well how driving aids in a connected environment assist lane-changing execution.As such,this study investigates the impact of a connected environment on lanechanging execution time during mandatory and discretionary lane-changing manoeuvres.To this end,this study designed an advanced driving simulator experiment where 78 drivers performed these manoeuvres on a simulated motorway in three randomised driving conditions.The conditions were baseline(without driving aids),a fully functioning connected environment with a perfect supply of driving aids,and an impaired connected environment with delayed driving aids.The lane-changing execution time has been modelled by a random parameters hazard-based duration modelling approach,which accounts for the panel nature of data and captures the unobserved heterogeneity.Results suggest that,compared to the baseline condition(i.e.,a non-connected environment),most of the drivers in the connected environment take more time to complete their lane-changing manoeuvres,indicating drivers’safer lane-changing execution behaviour in the connected environment.The communication delay driving condition has been found to have more deteriorating effects on mandatory lanechanging manoeuvres than discretionary lane-changing manoeuvres.This study concludes that(i)the connected environment increases safety margin during both lane-changing manoeuvres,and(ii)a higher magnitude of safety margin is observed during mandatory lane-changing manoeuvres whereby drivers have a higher need for assistance.