Khalil Shujaee

Delay independent stability conditions and decay estimates for time-varying functional differential equations

This paper presents sufficient delay independent conditions that guarantee stability of nonlinear time varying functional differential equations (FDEs). Estimates on the rate of decay of solutions are also obtained. >

eWellness: Building a Smart Hospital by Leveraging RFID Networks

The application of radio frequency identification (RFID) sensor networks pervasively to the hospital environment has the potential to improve efficiencies in operational aspects through accurate capture of fine grained data. The sensor nodes generate large amounts of real or near real-time data. Understanding and managing these data in the context of the hospital pose challenges for the middleware which has to connect sensor networks with hospital applications. In this paper we propose an edgeware paradigm of organizing hospital RFID sensor data based on the notion of an event. The event is defined and its properties are discussed. A three layered event representation and reasoning model is developed to map raw sensory information to semantic events in the application domains. A prototype system, called eWellness is build for the test of the local hospital

Collaborative information assurance capacity building at a consortium of colleges and universities

The objective of this project was to investigate, build and develop Information Assurance (IA) capacity at consortium of colleges and universities. This primary objectives of this project were (i) develop Information Security (IS) modules that are geared towards lower level undergraduate courses; and (ii) incorporate early research experiences that are vital towards building a cadre of high quality graduates who would be able to apply this knowledge in their workplaces. To date, we have developed a comprehensive curriculum for IS at consortium. We have achieved the first level Information Assurance Courseware Evaluation and are working toward the second phase of this project.

Free-surface Flow Simulations Using Parallel Finite Element Method

In this paper, we present recent results in numeri cal simulation of free-surface flows using the paral lel finite element method. In our approach, the gov erning equations are the Navier-Stokes equations written for two incompressible fluids. We solve these equations over a non-moving mesh. An inter face function with two distinct values serves as a marker identifying the location of the free-surface. This function is transported throughout the com putational domain with a time-dependent advec tion equation. The stabilized finite element method is used to discretize the governing equations. The finite element formulations are implemented in parallel using Message Passing Interface libraries. High performance computing tools and optimized techniques are utilized to solve applications on un structured meshes with more than one billion tetra hedral elements. Numerical examples include the simulation of sloshing in tanker trucks and ships hydrodynamics.

Architecting an Event-based Pervasive Sensing Environment in the Hospital

Radio frequency identification (RFID) sensor networks are increasingly being applied to the hospital environment. Capture of fine grained operational data in this environment can promote meaningful process reengineering with the objective of improving efficiencies in operational aspects. The RFID sensor nodes generate large amounts of fine grained real time data, related to resources and processes within the hospital environment. Understanding and managing these data in the context of the enterprise applications pose challenges for the middleware which has to connect sensor networks with enterprise applications. In this paper, we propose an architectural solution based on the notion of an event. The primary characteristics of an event are discussed and a three layered event representation model is developed to map raw sensory information to semantic events. A generalized event ontology language is proposed

Parallel simulation of two-phase flow problems using the finite element method

Parallel computation of unsteady, two-phase flow problems are performed using stabilized finite element method. The finite element formulations are written for fix meshes and are based on the Navier-Stokes equations and an advection equation governing the motion of the interface function. The interface function, with two distinct values serve as an marker identifying each fluid This function is advected with fluid velocity through out the computational domain. To increase the accuracy of the method, an interface-sharpening/mass conservation algorithm is designed. The method has been implemented on the CRAY T3E and also IBM SP/6000 using the MPI libraries. We show the effectiveness of the method in simulating complex 3D problems, such as two-fluid interface in a centrifuge tube, operation stability of a partially-filled tanker truck driving over a bump and hydrodynamics stability of ships.

Vibrational feedback control of time delay systems

This paper applies vibrational feedback control to time-lag systems. Both stabilization and transient issues are discussed. An illustrative example is given which demonstrates that the proposed controller: 1) provides superior system gain and phase margin in comparison to time invariant controllers when applied correctly; 2) is not robust with respect to unknown delays; and 3) does not have zero placement capabilities, in the sense defined in the paper.

Outlier detection in network data using the Betweenness Centrality

Outlier detection has been used to detect and, where appropriate, remove anomalous observations from data. It has important applications in the field of fraud detection, network robustness analysis, and intrusion detection. In this paper, we propose a Betweenness Centrality (BEC) as novel to determine the outlier in network analyses. The Betweenness Centrality of a vertex in a graph is a measure for the participation of the vertex in the shortest paths in the graph. The Betweenness centrality is widely used in network analyses. Especially in a social network, the recursive computation of the betweenness centralities of vertices is performed for the community detection and finding the influential user in the network. In this paper, we propose that this method is efficient in finding outlier in social network analyses. Furthermore we show the effectiveness of the new methods using the experiments data.

Stability of fast almost periodic systems with special classes of time varying delay

This paper develops stability criteria for fast oscillating linear systems with time varying state delay. The results are compared to known results for constant delay and for zero delay.<<ETX>>

Reliability-based optimization aimed for task allocation in heterogeneous distributed computing systems

This paper investigates the problem of allocating parallel application tasks to processors in heterogeneous distributed computing systems. The authors are proposing a simple, fast and effective algorithm to find the best possible solution with low computation time. The proposed algorithm uses the Correlation Density Rank (CDR) algorithm on the Virtual Allocation Network (VAN) in order to obtain reliability-based influence coefficients. Those coefficients are used to construct a simple linear programing as a new framework. We study the performance of the proposed algorithm over a wide range of parameters including problem size, the ratio of average communication time to average computation time, and task interaction density. The applicability and effectiveness of our algorithm is demonstrated by comparing with recently published related algorithms, which are found in the literature.