Kaysar Rahman

Function projective synchronization of memristor-based Cohen-Grossberg neural networks with time-varying delays.

AbstractThis paper deals with the problem of function projective synchronization for a class of memristor-based Cohen–Grossberg neural networks with time-varying delays. Based on the theory of differential equations with discontinuous right-hand side, some novel criteria are obtained to realize the function projective synchronization of addressed networks by combining open loop control and linear feedback control. As some special cases, several control strategies are given to ensure the realization of complete synchronization, anti-synchronization and the stabilization of the considered memristor-based Cohen–Grossberg neural network. Finally, a numerical example and its simulations are provided to demonstrate the effectiveness of the obtained results.

Some new semi-implicit finite difference schemes for numerical solution of Burgers equation

Some new liberalized semi implicit finite-difference method is proposed in this paper to solve one dimensional Burgers equation. Numerical results obtained by the present methods have been compared with exact solution and most of the existing numerical methods for different values of Reynolds number Re. The numerical results also show that they are in excellent agreement with the exact solution

RBAC Constraints Specification and Enforcement in Extended XACML

Constraints are considered to be the principal motivation for RBAC model. XACML profile for RBAC can not meet the need of expressing static and dynamic RBAC constraints well. We give the XACML syntax of common static and dynamic Separation of Duty constraints and cardinality constraints of RBAC. We also complement Role Enablement Authority to extend this profile in order to enforce these constraints.

Extending XACML profile for RBAC with semantic concepts

XACML is a widely accepted access control standard on the web. However, XACML policy files are hard to read and maintain, and quite difficult to express RBAC. In this paper, we extend XACML profile for RBAC using OWL in the motivation of simplifying policy administration with semantic concepts, and better synergy between XACML and RBAC. First we partly support RBAC policy of XACML with OWL. Then, we show how to use an OWL-DL reasoner to help XACML PDP to make access control decisions in the extended system architecture.

Attribute based access control constraint based on subject similarity

Access control constraint aims to avoid risky or sensitive set of objects being possessed by similar subjects. In order to improve the flexibility of constraints, this paper first examines potential inner-relationships among subjects, objects, and also the relationships between them in access control respectively, then proposes revised attribute-based access control constraint based on subject similarity. Test results shows this constraint is flexible. It effectively prevents similar subjects plot together to attack the application system.

CP-ABE Access Control Scheme for Sensitive Data Set Constraint with Hidden Access Policy and Constraint Policy

CP-ABE (Ciphertext-Policy Attribute-Based Encryption) with hidden access control policy enables data owners to share their encrypted data using cloud storage with authorized users while keeping the access control policies blinded. However, a mechanism to prevent users from achieving successive access to a data owner’s certain number of data objects, which present a conflict of interest or whose combination thereof is sensitive, has yet to be studied. In this paper, we analyze the underlying relations among these particular data objects, introduce the concept of the sensitive data set constraint, and propose a CP-ABE access control scheme with hidden attributes for the sensitive data set constraint. This scheme incorporates extensible, partially hidden constraint policy. In our scheme, due to the separation of duty principle, the duties of enforcing the access control policy and the constraint policy are divided into two independent entities to enhance security. The hidden constraint policy provides flexibility in that the data owner can partially change the sensitive data set constraint structure after the system has been set up.

Non-zero-sum cooperative access control game model with user trust and permission risk

Cooperative access control game model based on trust and risk is established.Different solutions are presented for the access control game with or without trust.Risky permission set problem is handled by solving the finite multi-stage game.Risk estimation method based on user trust and costs of permission is proposed. In access control, there exists a game between an application system and its user, in which both the system and the user try to maximize their own utility. Establishing a reasonable, general purpose access control game model of cost-benefit analysis is a non-trivial research issue. Considering the practical existence and involvement of user trust and permission risk, we construct a non-zero-sum game model for access control, choosing trust, and risk or cost as metrics in players payoff functions. We analyze the optimal strategies for the application system, the user, and also the Pareto efficient strategy from the viewpoint of both the application system and the user. A Nash equilibrium emerges that improves the rationality of access control decision-making under uncertain situations. In addition, we propose a proper risk estimation method. We also solve the risky permission set problem originated from access control constraints by utilizing optimal strategy in a finite multi-stage game.

Experimental Observation of the Skeletal Adaptive Repair Mechanism and Bionic Topology Optimization Method

Bone adaptive repair theory considers that the external load is the direct source of bone remodeling; bone achieves its maintenance by remodeling some microscopic damages due to external load during the process. This paper firstly observes CT data from the whole self-repairing process in bone defects in rabbit femur. Experimental result shows that during self-repairing process there exists an interaction relationship between spongy bone and enamel bone volume changes of bone defect, that is when volume of spongy bone increases, enamel bone decreases, and when volume of spongy bone decreases, enamel bone increases. Secondly according to this feature a bone remodeling model based on cross-type reaction-diffusion system influenced by mechanical stress is proposed. Finally, this model coupled with finite element method by using the element adding and removing process is used to simulate the self-repairing process and engineering optimization problems by considering the idea of bionic topology optimization.

A New Heuristic Topology Optimization Method Based on Bone Remodeling Model

The law of bone remodeling asserts that the internal trabecular bone adapts to external loadings, reorienting with the principal stress trajectories to maximize mechanical efficiency creating a naturally optimum structure. In this paper a new heuristic topology optimization method based on ordinary differential equations describing bone remodeling process is presented. The basis for numerical algorithm formulation was the phenomenon of bone adaptation to mechanical stimulation. The resulting optimization system allows fulling mechanical theorem for the stiffest design by use of presented heuristic topology optimization approach. Two widely used numerical examples are shown to confirm the validity and utility of the proposed topology optimization method.

Structural Topology Optimization Using Turing Model

In this paper firstly a new hypothetical model of bone remodeling based on bone bioactivity mechanism and Turing reaction-diffusion equations is presented. Secondly this model of bone remodeling is translated to material formation and resorption process of continuum structures, a new heuristic structural topology optimization is presented. Finally short cantilever beam problem, one of the widely used examples in structural topology optimization are carried out by using present method to confirm the validity of the proposed topology optimization method.