Computer Engineering Commons^™

Analysis Of Images Of Cells With Neurites, Florence Cloppet, Georges Stamon

Turkish Journal of Electrical Engineering and Computer Sciences

This study is concerned with the segmentation of cytological images and extraction of cellular entities in order to provide quantitative data about the number of cells in culture (statistical tests, morphology, model of evolution, etc). This quantitative supply is useful in biology to evaluate the consequences of the application of active substances on morphological changes and cellular viability. It is related to the conception of a system dedicated to automatic analysis of cell images, in order to evaluate the effects of drugs on the morphology of neuronal cells. We use a cooperative region / contour segmentation, which gives closed polygonal …

Imaging Electrical Current Density Using Nuclear Magnetic Resonance, B. Murat Eyüpoğlu, Ravinder Reddy, John S. Leigh

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, images of nonuniform and uniform electric current density in conductor phantoms, which contain magnetic resonance active nuclei, are produced using Magnetic Resonance Imaging (MRI). A standard spin echo pulse sequence is used, with the addition of a bipolar current pulse. The flux density parallel to the main magnetic field, generated by the current pulse, is encoded in the phase of the complex MR image. The spatial distribution of magnetic flux density is extracted from the phase image. Current density is calculated using the magnetic flux density. This fairly recent technique is known as Magnetic Resonance Current Density …

Use Of The Magnetic Field Generated By The Internal Distribution Of Injected Currents For Electrical Impedance Tomography (Mr-Eit), Y. Zi̇ya İder, Özlem Bi̇rgül

Turkish Journal of Electrical Engineering and Computer Sciences

In two dimensional conventional Electrical Impedance Tomography (EIT), volume conductor is probed by means of injected currents, and peripheral voltage measurements are used as input to the reconstruction algorithm. The current that flows in the 2D object creates magnetic fields that are perpendicular to the plane of imaging. Such magnetic fields can be measured using magnetic resonance tomography. In this study, use of this magnetic field generated by the injected currents, for the purpose of reconstructing the conductivity distribution, is studied. Sensitivity matrix relating the magnetic field to the element conductivities is calculated using the Finite Element Method and Biot-Savart …

Fdtd Evaluation Of The Sar Distribution In A Human Head Near A Mobile Cellular Phone, Selçuk Paker, Levent Sevgi̇

Turkish Journal of Electrical Engineering and Computer Sciences

In this study, Finite-Difference Time-Domain (FDTD) method is used to calculate the Specific Absorbtion Rate (SAR; defined as the power absorbed by unit mass of the tissue) distribution in a human head near a hand-held cellular phone. A three dimensional FDTD algorithm is built in cartesian coordinates. A discrete human head model, derived from a Nuclear Magnetic Resonance (NMR) image by semi-automatic algorithm, is located within FDTD volume together with a discrete hand-held receiver model. FDTD simulations are carried out for both european GSM (operating at 900MHz) and DECT (operating at 1.8GHz) systems with a quarter-wavelength antenna, mounted on top …

Cardiac Passive Acoustic Localization: Cardiopal, Yildirim Bahadirlar, Hali̇l Özcan Gülçür

Turkish Journal of Electrical Engineering and Computer Sciences

A novel non-invasive system is proposed as an adjunct diagnostic tool for cardiac disorders, which is based on processing of the heart sounds acquired using a specially designed 2-D passive acoustic array. In addition to the acoustic array, the system consists of a personal computer, specially developed instrumentation and interface hardware and an adaptive array processing scheme. A signal model is constructed in accordance with the basic assumptions made for very near-field low frequency sources. The multiple signal characterization (MUSIC) method together with the model is used for the localization of assumed point sources in the heart. Locations of the …

Integrating Security Into The Curriculum, Cynthia E. Irvine, Shiu-Kai Chin, Deborah Frincke

Electrical Engineering and Computer Science - All Scholarship

The number of skilled practitioners of computer security who are able to address the complexities of modern technology and are familiar with successful approaches to system security is very small. People want security but are faced with two difficulties. First, they do not know how to achieve it in the context of their enterprises. They may not even know of a way to translate organizational procedures into policies, much less implement a set of mechanisms to enforce those policies. Second, they have no way of knowing whether their chosen mechanisms are effective. The recent US Presidential Commission on Critical Infrastructure …

Stackguard: Automatic Adaptive Detection And Prevention Of Buffer-Overflow Attacks, Crispin Cowan, Calton Pu, David Maier, Heather Hinton, Jonathan Walpole, Peat Bakke, Steve Beattie, Aaron Grier, Perry Wagle, Qian Zhang

Computer Science Faculty Publications and Presentations

This paper presents a systematic solution to the persistent problem of buffer overflow attacks. Buffer overflow attacks gained notoriety in 1988 as part of the Morris Worm incident on the Internet. While it is fairly simple to fix individual buffer overflow vulnerabilities, buffer overflow attacks continue to this day. Hundreds of attacks have been discovered, and while most of the obvious vulnerabilities have now been patched, more sophisticated buffer overflow attacks continue to emerge.

We describe StackGuard: a simple compiler technique that virtually eliminates buffer overflow vulnerabilities with only modest performance penalties. Privileged programs that are recompiled with the StackGuard …

Object-Oriented Computer Simulations Of Physical Systems Using Dual Reciprocity Boundary Element Methodology, J. Friedrich

Turkish Journal of Electrical Engineering and Computer Sciences

Models of physical systems are essential in every engineering field. This work deals with computer simulations of physical systems that can be mathematically modelled by differential equations together with sufficient boundary conditions. The computer simulations are based on object-oriented technology and the dual reciprocity boundary element method which is a universal solution scheme for various types of partial differential equations (e.g. Laplace, Poisson, diffusion, convection-diffusion, and steady Navier-Stokes equation). This technique fulfills efficiency criteria like precision, robustness, versatility, programmability, user-friendliness, need of computational time and computer memory to a very high degree. This is demonstrated by three examples: Laplace's solution …

Distribution System Planning Usign Mixed Integer Programming, Belgin Türkay

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an improved mathematical model to optimise the size and locations of substations and the network routing problem. The model was formulated to minimise the total cost of the network by determining the optima of the substation locations and power, the load transfers between the demand centers, the feeder routes and the load flow in the network subject to a set of constraints. The computational results of a devised sample problem indicate that the developed optimisation model and its code are adequate for computer aided planning of distribution systems.

Analysis Of Nonlinear Sustained Oscillations In Discrete Systems With Backlash And Resolution By Using A Discretization-Oriented Describing Function, M. De La Sen, A. Pena, J. Esnaola

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a discretization-oriented describing function is derived for nonlinear devices combining backlash and quantization (resolution) while being subject to discretization through a sampler and zero-order hold. Such a describing function is frequency-dependent so that the overall nonlinearity, which includes both resolution and backlash, is interpreted as possessing nonlinear inertia. That nonlinear inertia is generated by the sampling process, since it does not appear if the system is continuous. The presence of nonlinear sustained oscillations (limit cycles) is investigated through simulations.

Signal Injection With Perceptual Criteria, T. Engi̇n Tuncer

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a novel method for increasing the coding performance and information transmission capacity is presented. This method is mainly based on perceptual modelling of input signal such as speech or audio. Presented approach may be seen as an alternative to transforms which dynamically change analysis window for better energy compaction. A perceptual model is established in order to obtain a global masking threshold in frequency below which sounds become inaudible. Certain criteria are developed for identifying the signal injection bands. A new multiband filter design method which is a generalization of windowing method is used to separate the …

State Of Art In Realistic Head Modeling For Electro-Magnetic Source Imaging Of The Human Brain, Nevzat G. Gençer, İ. Oğuz Tanzer, M. Kemal Özdemi̇r, Can E. Acar, Mert Sungur

Turkish Journal of Electrical Engineering and Computer Sciences

Electric currents produced by the neural activity in the brain create electric potentials on the scalp and magnetic field distribution outside the scalp. Measuring electric and magnetic fields provides a means to understand the spatio-temporal distribution of the neural activity. The representations of the intracellular electric current of active cell populations based on bimodal data are called electro-magnetic source image (EMSI). With the recent development of large arrays of magnetic sensors, and systems for measuring scalp voltages at more than 100 locations, it is now feasible to implement computational methods that employ numerical models which incorporate the correct geometry and …

Electromagnetic Beam Directing Means-Sample Analysis System Stage, And Method Of Use, Daniel W. Thomspon, Darin W. Glenn, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

Disclosed is an electromagnetic beam directing means for use with sample analysis systems, such as relfectometers, ellipsometers and polarimeters and the like, use of which facilitates investigation of sample systems which are not mounted to a sample analysis system sample system supporting stage. The present invention eliminates the requirement os extensice sample analysis system component realignment when alternatingly performing analysis of sample systems mounted upon, and mounted other than upon, a sample analysis system sample system supporting stage.

Cognitive Agents, Michael N. Huhns, Munindar P. Singh

Faculty Publications

Several researchers have proposed using cognitive concepts as a semantic basis for agent communications (M.N. Huhns and M.P. Singh, 1997). One of the leading candidates for such a semantics is based on Arcol, the communication language used within Artimis. Interestingly, this application (not only of Arcol, but also in general) appears extremely misguided. The intentional concepts are well suited to designing agents, but are not suited to giving a basis to a public, standardizable view of communication. A challenge for using the cognitive concepts is that although they are natural in several respects and can guide implementations, full blown implementations …

Personal Assistants, Michael N. Huhns, Munindar P. Singh

Faculty Publications

Already there are simple personal agents to help with some of our shopping. There are agents to track stocks in our portfolios, advise us on how to use particular software products, and arrange meetings within corporate workgroups. However, none of these agents takes more than one aspect of our activities into account, nor do they adapt easily to our preferences. Personal assistants, on the other hand, are agents that can represent individuals on the Web. They help users in their day-to-day activities, especially those involving information retrieval, negotiation, or coordination. A personal assistant might schedule a meeting and then, based …

Workflow Agents, Michael N. Huhns, Munindar P. Singh

Faculty Publications

Software agents as user agents, resource agents, and brokers may be able to enhance usefulness of workflow applications. Workflow technology is important to network computing because workflows exist naturally wherever distributed resources are interrelated. The problem with current workflow technology is that it is often too rigid. The lack of freedom accorded to human participants causes workflow management systems to appear unfriendly. As a result, they are often ignored or circumvented. This rigidity also causes productivity losses by making it harder to accommodate the flexible, ad hoc reasoning of human intelligence. Another challenge is that system requirements are rarely static. …

Anthropoid Agents, Michael N. Huhns, Munindar P. Singh

Faculty Publications

In the study of agents on the Internet, we often ascribe to them human qualities, such as beliefs and intentions. These qualities are best understood as metaphors that give developers a way to talk about and design the capabilities and applications of agents. Despite all the progress in computing, users have been slow to accept the technology. They have often accepted what was thrown at them, but only under economic duress. Bringing the technology closer to their emotional needs might ease this resistance. So how can we put a human face on computing? Maybe by putting an animated face on …

A Multithreaded Scheduler For A High-Speed Simulator, Gene Saghi, Kirk Reinholtz, Paul Savory

Department of Industrial and Management Systems Engineering: Faculty Publications

The Cassini spacecraft is on its journey to Saturn to perform a close-up study of the Saturnian system; its rings, moons, magneto-sphere, and the planet itself. Sequences of commands will be sent to the spacecraft by ground personnel to control every aspect of the mission. To validate and verify these command sequences, a bit-level, high-speed simulator (HSS) has been developed. To maximize performance, the HSS is implemented with multiple threads and runs on a multiprocessor system. A key component of the HSS is the scheduler, which controls the execution of the simulator. The general framework of the scheduler can be …

Agent Jurisprudence, Michael N. Huhns, Munindar P. Singh

Faculty Publications

The agent metaphor comes packaged with a number of powerful abstractions. Some of these are psychological, such as beliefs, knowledge, and intentions-abstractions that were traditionally studied in AI. However, there are a number of other abstractions that the agent metaphor brings to the fore. Of these, one has been emphasizing the social abstractions. Close cousins of the social abstractions are the ethical and legal abstractions. These too are being recognized as increasingly important in developing agents that are not only sociable, but also well behaved.

Adaptive Shape From Shading, Ati̇lla Gülteki̇n, Muhi̇tti̇n Gökmen

Turkish Journal of Electrical Engineering and Computer Sciences

Extracting surface orientation and surface depth from one or more images is one of the classic problems in computer vision. Shape-from-shading (SFS) deals with the recovery of 3-D shape from a single shaded image. The shape is recovered by minimizing an energy functional involving constraints such as smoothness. In this constrained problem, although the smoothness constraint helps to stabilize the minimization process, it pushes the reconstruction toward a smooth surface. In this paper, we present a new adaptive shape-from-shading method which reduces this oversmoothing by controlling the smoothness spatially over the image space. In order to improve the quality of …

A Parallel Pipelined Computer Architecture For Digital Signal Processing, Haluk Gümüşkaya, Bülent Örenci̇k

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a parallel pipelined computer architecture and its six network configurations targeted for the implementation of a wide range of digital signal processing (DSP) algorithms described by both atomic and large grain data flow graphs. The proposed architecture is considered together with programmability, yielding a system solution that combines extensive concurrency with simple programming. It is an SSIMD (Skewed Single Instruction Multiple Data) or MIMD (Multiple Instruction Multiple Data) machine depending on the algorithms implemented and the programming methodologies. The concurrency that can be exploited by the algorithms using this Parallel pipelined architecture is both temporal and spatial …

Hierarchical Interconnection Network Architecture For Real-Time Systems, Bülent Örenci̇k

Turkish Journal of Electrical Engineering and Computer Sciences

A hierarchical network suitable for interconnection of real-time client processes in a distributed multiprocessor environment is presented in this paper. A multi-layer {\it Communication Unit} (CU) prototype is developed for this purpose. This unit offers the client processes communication services for real-time operation. These services are structured in such a way that they do not depend on the characteristics of the communication medium. The basic hardware of the CU consists of a PC compatible card connected to the VME Bus. Client processes run on target cards (Motorola MVME-162) which are attached to the same bus. Target cards together with a …

Imaging Tissue Conductivity Via Contactless Measurements: A Feasibility Study, Nevzat G. Gençer, M. Nejat Tek

Turkish Journal of Electrical Engineering and Computer Sciences

The feasibility of a new imaging system is investigated. This system will be used to image electrical conductivity distribution of biological tissues via contactless measurements. This will be achieved by introducing currents in the conductive medium using time-varying magnetic fields and measuring the magnetic fields of the induced currents. Consequently, the imaging system consists of transmitter and receiver coils placed nearby the conductive body. In this study, the basic features of the coplanar and coaxial coils are studied. The validity of the simplifying assumptions for the governing field equations is investigated. It is found that, for operating frequency of 100 …

Study Of Electronic Cash: Its Impact On The Economy And Society, And Its Future, Sanjana Prasad

LLM Theses and Essays

Technological advancement has introduced an electronic method for the payment for goods and services. With these advancements and the growth of the internet, the market-place of the world has become one universe without borders. This paper examines the various methods of electronic payment for goods and services and the domestic and international laws that govern their operations. The paper explores concerns about money laundering, counterfeiting, internet security, cyber scams in electronic cash as well as proffered security solutions to these problems. The paper concludes with the proposition that electronic cash in the form of cards (ATM) are more accessible to …

Proposed Model Rules Governing The Admissibility Of Computer-Generated Evidence, Lynn Mclain, James E. Carbine

All Faculty Scholarship

Pursuant to a grant from the State Justice Institute, the Court of Appeals of Maryland Standing Committee on Rules of Practice and Procedure drafted, and the Court of Appeals adopted, model rules regarding computer-generated animations and simulations. The rules address discovery, pretrial rulings, and preservation of the record for appeal.

Usable Software And It's Attributes: A Synthesis Of Software Quality: European Community Law And Human-Computer Interaction., Ronan Fitzpatrick, Catherine Higgins

Conference papers

Strategic managers and IS professionals who are responsible for specifying, acquiring and producing quality software products are not supported by the endless flow of new international standards, legislation and user requirements. In order to clarify the current situation for everybody concerned with software quality, and especially those interested in usability, there is a need for a new review and evaluation of the various strands that contribute to software quality. By way of review this paper recalls the original software quality factors which were defined twenty years ago by McCall et al. and presents a methodical analysis and synthesis of three …

A Corba-Base Integration Of Distributed Electronic Healthcare Records Using The Synapses Approach, Jane Grimson, William Grimson, Damon Berry, Gaye Stephens, Eoghan Felton, Dipak Kalra, Pieter Toussaint, Onno Weir

Articles

The ability to exchange in a meaningful, secure, and simple fashion relevant healthcare data about patients is seen as vital in the context of efficient and cost-effective shared or team-based care. The electronic healthcare record (EHCR) lies at the heart of this information exchange, and it follows that there is an urgent need to address the ability to share EHCR's or parts of records between carers and across distributed health information systems. This paper presents the Synapses approach to sharing based on a standardized shared record, the Federated Healthcare Record, which is implemented in an open and flexible manner using …

All Agents Are Not Created Equal, Michael N. Huhns, Munindar P. Singh

Faculty Publications

As the technology advances, we can expect the development of specialized agents to be used as standardized building blocks for information systems. Two trends lend credence to such a prediction. First, software systems in general are being constructed with larger components, such as ActiveX and JavaBeans, which are becoming closer to being agents themselves. They have more functionality than simple objects, respond to events autonomously, and, most importantly, respond to system builders at development time, as well as to events at runtime. Moreover, there is a move toward more cooperative information systems, in which the architecture itself plays an important …

Building A Secure Intranet, Fred J. Berryman

Theses

This thesis will explain the vulnerabilities of computers in a networking environment and demonstrate proper procedures for building a secure Intranet.

The Internet is built around the concept of open communication. Data is shared around the globe just as easily as it is from one office or cubical to the next. Corporations are skeptical about putting company data on such a public transport mechanism as the Internet, but the tools used on the Internet are exciting and everyone wants to use them. Out of a desire for the best of both worlds, the Intranet was born.

An intranet that has …

Digital Receivers, George Rofa

Theses : Honours

No abstract provided.