Electrical and Computer Engineering Publications and Research

Optical coherence elastography: current status and future applications

Cuiru Sun et al. — Thu, 04 Apr 2013 06:08:50 PDT

Optical coherence tomography (OCT) has several advantages over other imaging modalities, such as angiography and ultrasound, due to its inherently high in vivoresolution, which allows for the identification of morphological tissue structures. Optical coherence elastography (OCE) benefits from the superior spatial resolution of OCT and has promising applications, including cancer diagnosis and the detailed characterization of arterial wall biomechanics, both of which are based on the elastic properties of the tissue under investigation. We present OCE principles based on techniques associated with static and dynamic tissue excitation, and their corresponding elastogram image-reconstruction algorithms are reviewed. OCE techniques, including the development of intravascular- or catheter-based OCE, are in their early stages of development but show great promise for surgical oncology or intravascular cardiology applications.

Detecting apoptosis using dynamic light scattering with optical coherence tomography

Golnaz Farhat et al. — Thu, 04 Apr 2013 05:56:14 PDT

A dynamic light scattering technique is implemented using optical coherence tomography (OCT) to measure the change in intracellular motion as cells undergo apoptosis. Acute myeloid leukemia cells were treated with cisplatin and imaged at a frame rate of 166 Hz using a 1300 nm swept-source OCT system at various times over a period of 48 h. Time correlation analysis of the speckle intensities indicated a significant increase in intracellular motion 24 h after treatment. This rise in intracellular motion correlated with histological findings of irregularly shaped and fragmented cells indicative of cell membrane blebbing and fragmentation.

Comprehensive data visualization for high resolution endovascular carotid arterial wall imaging

Kyle HY Cheng et al. — Wed, 03 Apr 2013 12:51:03 PDT

Carotid angioplasty and stenting is a minimally invasive endovascular procedure that may benefit from in vivo high resolution imaging for monitoring the physical placement of the stent and potential complications. The purpose of this pilot study was to evaluate the ability of optical coherence tomography to construct high resolution 2D and 3D images of stenting in porcine carotid artery. Four Yorkshire pigs were anaesthetized and catheterized. A state-of-the-art optical coherence tomography (OCT) system and an automated injector were used to obtain both healthy and stented porcine carotid artery images. Data obtained were then processed for visualization. The state-of-the-art OCT system was able to capture high resolution images of both healthy and stented carotid arteries. High quality 3D images of healthy and stented carotid arteries were constructed, clearly depicting vessel wall morphological features, stent apposition and thrombus formation over the inserted stent. The results demonstrate that OCT can be used to generate high quality 3D images of carotid arterial stents for accurate diagnosis of stent apposition and complications under appropriate imaging conditions.

Evaluation of an electronic video game for improvement of balance

Kristiina M. Valter McConville et al. — Fri, 18 May 2012 05:56:34 PDT

Virtual environments have been investigated for fitness and medical rehabilitation. In this study, the Sony EyeToy (R) and PlayStation 2 (R) were used with the Anti-Grav (TM) game to evaluate their potential for improving postural balance. The game required lateral head, body, and arm movements. The performance on balance tests of subjects who trained for 3 weeks with this game was compared to the performance of controls who were not trained. Training subjects showed improvement for two of the three tests (each testing a different facet of balance), suggesting specificity of training, while control subjects did not show significant improvement on any test. Simulator sickness questionnaire results showed a variety of mild symptoms, which decreased over the training sessions. Motor learning analysis of the game scores showed that mastery had been achieved on the easier level in the game, but not on the second level of difficulty. This reflects the potential for continued learning and training through advanced levels within a game. A model parameter using the time constants of game score improvement was developed, which could be used to quantify the difficulty for any video game design. The results suggest that this video game could be used for some aspects of balance training.

Characteristics of directly modulated ROF link for wireless access

Xavier N. Fernando et al. — Mon, 29 Nov 2010 11:27:51 PST

The radio-over-fiber (ROF) link is of much interest to provide broadband wireless access. In this paper, we discuss some characteristics of a directly modulated ROF link in CDMA and FDMA environments. These RF measurement results show that, though the ROF link has adequate bandwidth to support several radio channels, nonlinear distortion and power loss, mainly due to electrical to optical conversion process and vice versa, limit the performance. Especially, the AM-PM type nonlinearity that starts at low power levels is a bigger concern. Furthermore, the spurious free dynamic range (SFDR) decreases because of the increases with the bandwidth of the RF signal.

A study of DiffServ based QoS issues in next generation mobile networks

Thimma V.J. Ganesh Babu et al. — Mon, 29 Nov 2010 11:13:47 PST

To provide data rates of the order of hundreds of Mbps and multimedia services, standardization efforts for next generation (4G) systems are focusing on target technologies and seamless connectivity through various types of networks, including wireline networks and WLANs. Different types of multiple access techniques, such as the ones based on multicarrier CDMA and OFDM (orthogonal frequency division multiplexing) have been proposed. There is a need for functional integration of the multiple networks, and, with the evolution of IPv6 and QoS support for IP networks, an IP based interconnectivity is best suited. A QoS aware adaptive radio resource management technique based on multi-code multicarrier CDMA is discussed. We develop a novel radio access method and develop algorithms for allocating and controlling radio network resources so that system performance can be maximized and guaranteed QoS for multimedia services can be provided within the DiffServ environment.

Re-Configurable Parallel Stream Processor with Self-Assembling and Self-Restorable Micro-Architecture

Lev Kirischian et al. — Mon, 29 Nov 2010 11:13:46 PST

In this paper we present a concept of the self-assembling micro-architectures of Application Specific Virtual Processors for data-stream processing. The procedure for micro-architecture assembling is developed for Xilinx "Virtex" FPGA devices. It is shown that proposed approach allows a minimization of system resources for multi-task data-stream workload and gives ability for self-restoration of processing micro-architectures when hardware fault occurs. This Paper presents a description of system level architecture of run-time re-configurable multi-stream parallel processor for video applications and results gained on the prototype.

Application of grammar-based codes for lossless compression of digital mammograms

Xiaoli Li et al. — Fri, 26 Nov 2010 12:08:32 PST

A newly developed grammar-based lossless source coding theory and its implementation was proposed in 1999 and 2000, respectively, by Yang and Kieffer. The code first transforms the original data sequence into an irreducible context-free grammar, which is then compressed using arithmetic coding. In the study of grammarbased coding for mammography applications, we encountered two issues: processing time and limited number of single-character grammar G variables. For the first issue, we discover a feature that can simplify the matching subsequence search in the irreducible grammar transform process. Using this discovery, an extended grammar code technique is proposed and the processing time of the grammar code can be significantly reduced. For the second issue, we propose to use double-character symbols to increase the number of grammar variables. Under the condition that all the G variables have the same probability of being used, our analysis shows that the double- and single-character approaches have the same compression rates. By using the methods proposed, we show that the grammar code can outperform three other schemes: Lempel-Ziv-Welch (LZW), arithmetic, and Huffman on compression ratio, and has similar error tolerance capabilities as LZW coding undersimilar circumstances.

Global View Of A Sustainable Society And Its Stability

Helmut Burkhardt — Fri, 26 Nov 2010 07:32:10 PST

It is often said, and at present it is probably true that famine and poverty in some parts of the world are a problem of distribution rather than one of production of the necessities of life. The improvement of our distribution system, however, does not only solve an acute problem of regional deprivation, but also creates regional interdependence. Thus, with present day transcontinental trade the questions related to sustainability become global issues. The whole world is an interconnected network. Is there some "invisible hand" which guides local actions in a direction beneficial to the whole or does this connectedness necessitate deliberate global planning?

A similar question arises when we look far ahead in time. Many people have a blind trust in the future and are unconcerned with questions of long term sustainability of human civilization. Those who believe in science and technology respond to warnings of global sustenance problems: "The engineers will invent something that will solve our problems." Those with a religious bent say: "Why worry about tomorrow? 'He' who has provided for us in the past will do so in the future." How useful is this fatalistic stance today? Given the knowledge we possess, are we not responsible for irreversible damages to the Planet which will burden future generations? Is mankind capable of consciously choosing its future path?

This paper analyses the state of the World and the stability of the processes in it. We take a global and long term perspective. The basic tool used is a balance equation for material, cultural, biological, social and ecological substances. Conditions for sustainable, dynamic equilibria are derived and presented in per capita values in order to facilitate intuitive comprehension. Possible contributions to sustainability of the natural sciences and engineering and of the social sciences and the humanities are outlined. In conclusion some desirable and some accidental paths to sustainability are given.

Control of the Metal Rolling Process: A Multidimensional System Approach

S Foda et al. — Fri, 26 Nov 2010 07:32:09 PST

The metal-rotting process is modelled as a delay differential system with noncommensurate delays. Stability conditions for delay differential systems have been recently developed using asymptotic stability tests and the Lyapunov approach. These results are applied to the stability analysis and stabilization of the metal rolling process. Conditions on the gains of finite dimensional controllers such as proportional plus derivative controllers are developed to ensure the stability of the controlled process against delay variations.

Calculation of arc-circuit asymmetry in electric-arc furnaces

Peter F. Ryff — Fri, 26 Nov 2010 07:32:09 PST

A method is described to determine the arc voltages on a per-phase basis of a 3-phase direct electricarc furnace. Having determined the arc voltages, other arc parameters, such as arc resistance, length and power, can then be obtained. By using the procedure outlined, in conjunction with experimental data on a 100 t, 5Â½m diameter shell furnace having a triangulated secondary electrical system, it will be shown that controlling arc powers by means of the impedance control method still results in asymmetric furnace operation. Sample calculations are included, illustrating actual conditions for this furnace.

Appropriate Curriculum: Enabling The Student To Meet The Transdisciplinary Challenges Of A Sustainable Society

Helmut Burkhardt — Fri, 26 Nov 2010 07:32:08 PST

A sustainable society at present world population levels is faced with many complex issues: curbing further human population growth, preventing nuclear, biological or chemical wars, soothing social and political tensions, fighting poverty, protecting the environment from poison and climatic change, coping with resource scarcity, and managing vulnerable ecosystems. Each one of the items in this list transcends our conventional disciplines. Considering further that all of the problems are connected makes it obvious that neither a scientifically illiterate public nor our professionals, traditionally trained in narrow disciplines, are capable of creating or maintaining a sustainable society.

Scientific and ordinary literacy of the general public is a desirable if not a necessary preparation for a sustainable society. Can it be achieved through our present educational means, or is it necessary for education to change? Today, the alphabet and grammar have become simple enough for all to learn how to read and write with a minor effort, and illiteracy in developed countries is now the exception rather than the rule. Unfortunately, this is not the case with scientific literacy. To learn science today is hard and time consuming. Our scientific and engineering knowledge is fragmented into many disciplines, and our curricula in these fields are cluttered with insignificant details. The frustrating information overload prevents most contemporaries from becoming scientifically literate, and it is difficult to get even the simplest of scientific truths to a wide public.

A new knowledge structure for the development of a unified science curriculum is presented in this paper. By using universal concepts and universally applicable algorithms of thinking, a knowledge core is presented which connects all the disciplines and avoids duplication. It is concluded that such a unified science reduces the quantity of information required for a broad view of existing knowledge, that the reduced effort in learning such a universal mental tool will motivate more students to think scientifically about broad issues, and that the professionals trained in transdisciplinary sciences will be able to see the "big picture" of the problems facing a sustainable society.

Innovative initiatives in control education at Ryerson Polytechnic University. Fuzzy-logic control of the 3D-helicopter simulator

M S. Zywno et al. — Thu, 25 Nov 2010 13:56:46 PST

This paper describes one of projects undertaken at Ryerson Polytechnic University to integrate emerging trends in control engineering into the undergraduate curriculum. An intelligent control scheme based on fuzzy-logic, and developed for an experimental setup, is discussed. The process is a highly coupled 8th-order, multi-input multi-output, 3 degrees-of-freedom simulator of a helicopter. Currently the setup is used to develop control strategies for undergraduate thesis students. Eventually, the process will also be accessible to students remotely over the World Wide Web. The controller performance with the fuzzy-logic control (FLC) is benchmarked against that of a conventional controller. The simulations show that the system performance under FLC does not deteriorate away from the equilibrium point and remains comparable with, or superior to, the performance under the linear control, over the whole range of operating conditions of this setup.

A practical servomotor project: combining the Web with simulation tools to solidify concepts in undergraduate control education

M S. Zywno et al. — Thu, 25 Nov 2010 13:56:45 PST

Current technology enables the lecturer to use computer tools to enhance the conceptualisation of lecture material. This can be especially useful in an engineering curriculum, as the course material can be rendered less abstract through visual illustration of difficult mathematical concepts. In this paper, we present an example of a multimedia enhanced course in linear control theory, taught by authors at Ryerson Polytechnic University (Toronto, Canada). In our implementation of the course, we combine software simulations of practical systems to illustrate control theory concepts with extensive online course notes to assist with comprehension. Followup analysis shows that the use of the WWW and computer tools to enhance the learning process leads to increased enthusiasm, comprehension, and information retention. A review of the process required to create the technology enabled learning environment shows that initially there is a great deal of work involved. However, we conclude that the effort is justified by allowing a positive qualitative change in the way we educate engineering students

Application Of Mathieu functions And The Point Matching Method To Elliptic Conductors

Wisnu Wurjantara et al. — Thu, 25 Nov 2010 13:56:45 PST

Analysis of elliptic conductors, carrying a known total current, using the point matching method (PMM) in circular-cylinder coordinates [l] failed for the values of axes ratio b / a < 05, where a and b are the major and minor axes of the ellipse, respectively. This work shows that the use of elliptic-cylinder coordinates in conjunction with the point matching method overcomes this problem. This paper is a part of the work investigating the difficulties encountered in the point matching method, and is motivated by the fact that, despite its limitations, the method is still attractive as suggested by its use in recent papers [2]-141.

Low voltage cascode amplifier

S Ardalan et al. — Thu, 25 Nov 2010 13:56:44 PST

A 0.8 V folded cascode operational amplifier was designed in 0.18 μm standard CMOS technology. Emphasis was placed on observing the low voltage design and using a current driven bulk (CDB) technique to achieve this goal. The CDB technique was introduced as a method for low voltage design by reducing the threshold voltage. This design achieves 141 dB DC gain, 56 MHz 3 dB bandwidth and 65 GHz gain bandwidth, which is the working condition of pipeline ADCs.

Heart rate variability and short duration spaceflight: relationship to post-flight orthostatic intolerance

Andrew P. Blaber et al. — Mon, 08 Nov 2010 10:35:27 PST

Background: Upon return from space many astronauts experience symptoms of orthostatic intolerance. Research has implicated altered autonomic cardiovascular regulation due to spaceflight with further evidence to suggest that there might be pre-flight autonomic indicators of post-flight orthostatic intolerance. We used heart rate variability (HRV) to determine whether autonomic regulation of the heart in astronauts who did or did not experience post-flight orthostatic intolerance was different pre-flight and/or was differentially affected by short duration (8 – 16 days) spaceflight. HRV data from ten-minute stand tests collected from the 29 astronauts 10 days preflight, on landing day and three days post-flight were analysed using coarse graining spectral analysis. From the total power (PTOT), the harmonic component was extracted and divided into high (PHI: >0.15 Hz) and low (PLO: = 0.15 Hz) frequency power regions. Given the distribution of autonomic nervous system activity with frequency at the sinus node, PHI/PTOT was used as an indicator of parasympathetic activity; PLO/PTOT as an indicator of sympathetic activity; and, PLO/PHI as an estimate of sympathovagal balance.

Results: Twenty-one astronauts were classified as finishers, and eight as non-finishers, based on their ability to remain standing for 10 minutes on landing day. Pre-flight, non-finishers had a higher supine PHI/PTOT than finishers. Supine PHI/PTOT was the same pre-flight and on landing day in the finishers; whereas, in the non-finishers it was reduced. The ratio PLO/PHI was lower in non-finishers compared to finishers and was unaffected by spaceflight. Pre-flight, both finishers and non-finishers had similar supine values of PLO/PTOT, which increased from supine to stand. Following spaceflight, only the finishers had an increase in PLO/PTOT from supine to stand.

Conclusions: Both finishers and non-finishers had an increase in sympathetic activity with stand on pre-flight, yet only finishers retained this response on landing day. Non-finishers also had lower sympathovagal balance and higher pre-flight supine parasympathetic activity than finishers. These results suggest pre-flight autonomic status and post-flight impairment in autonomic control of the heart may contribute to orthostatic intolerance. The mechanism by which higher pre-flight parasympathetic activity might contribute to post-flight orthostatic intolerance is not understood and requires further investigation.

Control Methods for Low Voltage Ride-Through Compliance in Grid-Connected NPC Converter Based Wind Power Systems Using Predictive Control

S Alepuz et al. — Fri, 05 Nov 2010 11:32:17 PDT

In presence of grid voltage dips, Low Voltage Ride-Through (LVRT) requirements demand the wind power plant to remain connected to the grid, helping the network to keep voltage and frequency stable. Neutral-Point-Clamped (NPC) converters are appropriate for wind power systems, because the current trend of increasing voltage levels. Predictive current control presents as fast dynamic response and accurate reference tracking as other well established control methods, while providing more flexibility. In this work, three different control strategies are applied to the grid-side NPC converter, in order to fulfil LVRT requirements, which are implemented with the predictive current control technique. Dc-link neutral point voltage is kept balanced by the predictive control algorithm, using the redundant switching states of the NPC converter. Simulation results confirm the validity of the proposed control approach.

Colony size measurement of the yeast gene deletion strains for functional genomics

Negar Memarian et al. — Fri, 05 Nov 2010 09:00:41 PDT

Background: Numerous functional genomics approaches have been developed to study the model organism yeast, Saccharomyces cerevisiae, with the aim of systematically understanding the biology of the cell. Some of these techniques are based on yeast growth differences under different conditions, such as those generated by gene mutations, chemicals or both. Manual inspection of the yeast colonies that are grown under different conditions is often used as a method to detect such growth differences.

Results: Here, we developed a computerized image analysis system called Growth Detector (GD), to automatically acquire quantitative and comparative information for yeast colony growth. GD offers great convenience and accuracy over the currently used manual growth measurement method. It distinguishes true yeast colonies in a digital image and provides an accurate coordinate oriented map of the colony areas. Some post-processing calculations are also conducted. Using GD, we successfully detected a genetic linkage between the molecular activity of the plant-derived antifungal compound berberine and gene expression components, among other cellular processes. A novel association for the yeast mek1 gene with DNA damage repair was also identified by GD and confirmed by a plasmid repair assay. The results demonstrate the usefulness of GD for yeast functional genomics research.

Conclusion: GD offers significant improvement over the manual inspection method to detect relative yeast colony size differences. The speed and accuracy associated with GD makes it an ideal choice for large-scale functional genomics investigations.

Infrared thermography as an access pathway for individuals with severe motor impairments

Negar Memarian et al. — Fri, 05 Nov 2010 09:00:40 PDT

Background: People with severe motor impairments often require an alternative access pathway, such as a binary switch, to communicate and to interact with their environment. A wide range of access pathways have been developed from simple mechanical switches to sophisticated physiological ones. In this manuscript we report the inaugural investigation of infrared thermography as a non-invasive and non-contact access pathway by which individuals with disabilities can interact and perhaps eventually communicate.

Methods: Our method exploits the local temperature changes associated with mouth opening/closing to enable a highly sensitive and specific binary switch. Ten participants (two with severe disabilities) provided examples of mouth opening and closing. Thermographic videos of each participant were recorded with an infrared thermal camera and processed using a computerized algorithm. The algorithm detected a mouth open-close pattern using a combination of adaptive thermal intensity filtering, motion tracking and morphological analysis.

Results: High detection sensitivity and low error rate were achieved for the majority of the participants (mean sensitivity of all participants: 88.5% ± 11.3; mean specificity of all participants: 99.4% ± 0.7). The algorithm performance was robust against participant motion and changes in the background scene.

Conclusion: Our findings suggest that further research on the infrared thermographic access pathway is warranted. Flexible camera location, convenience of use and robustness to ambient lighting levels, changes in background scene and extraneous body movements make this a potential new access modality that can be used night or day in unconstrained environments.