Price Faculty of Engineering Scholarly Works

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http://hdl.handle.net/1993/36351

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Open Access
A Stand-Alone Magnetic Bubble Memory
(1981-1-1) Kinsner, W.; Joll, B. S.
Open Access
A Theory of Bubbles in Ion-implanted Structures
(1981-1-1) Kinsner, W.
Open Access
A finite capacity queue with Markovian arrivals and two servers with group services
(1994-1-1) Chakravarthy, S.; Alfa, Attahiru Sule
In this paper we consider a finite capacity queuing system in which arrivals are governed by a Markovian arrival process. The system is attended by two exponential servers, who offer services in groups of varying sizes. The service rates may depend on the number of customers in service. Using Markov theory, we study this finite capacity queuing model in detail by obtaining numerically stable expressions for (a) the steady-state queue length densities at arrivals and at arbitrary time points; (b) the Laplace-Stieltjes transform of the stationary waiting time distribution of an admitted customer at points of arrivals. The stationary waiting time distribution is shown to be of phase type when the interarrival times are of phase type. Efficient algorithmic procedures for computing the steady-state queue length densities and other system performance measures are discussed. A conjecture on the nature of the mean waiting time is proposed. Some illustrative numerical examples are presented.
Open Access
A discrete single server queue with Markovian arrivals and phase type group services
(1995-1-1) Alfa, Attahiru Sule; Dolhun, K. Laurie; Chakravarthy, S.
We consider a single-server discrete queueing system in which arrivals occur according to a Markovian arrival process. Service is provided in groups of size no more than M customers. The service times are assumed to follow a discrete phase type distribution, whose representation may depend on the group size. Under a probabilistic service rule, which depends on the number of customers waiting in the queue, this system is studied as a Markov process. This type of queueing system is encountered in the operations of an automatic storage retrieval system. The steady-state probability vector is shown to be of (modified) matrix-geometric type. Efficient algorithmic procedures for the computation of the rate matrix, steady-state probability vector, and some important system performance measures are developed. The steady-state waiting time distribution is derived explicitly. Some numerical examples are presented.
Open Access
Fairness in Radio Resource Management for Wireless Networks
(2009-04-08) Ahmed, MohamedHossam; Anpalagan, Alagan; Chen, Kwang-Cheng; Han, Zhu; Hossain, Ekram
Open Access
RF Cavity Passive Wireless Sensors With Time-Domain Gating-Based Interrogation for SHM of Civil Structures
(IEEE, 2009-11) thomson, douglas j; card, dan; bridges, greg e
Many existing sensing technologies for application to the monitoring of large systems or civil structures have a serious deficiency in that they require some type of wired physical connection to the outside world. This causes significant problems in the installation and long term use of these sensors. This paper describes a new type of passive wireless sensor that is based on resonant RF cavities, where the resonant frequency is modulated by a measurand. In the case of a strain sensor, the electrical length of the cavity directly modulates it’s resonant frequency. A probe inside the cavity couples RF signals from the cavity to an externally attached antenna. The sensor can then be interrogated remotely using microwave pulse-echo techniques. Such a system has the advantage of requiring no permanent physical connection between the sensor and the data acquisition system. In this type of sensor the RF interrogation signal is transmitted to the sensor and then re-radiated back to the interrogator from the sensor resulting in a signal strength that decreases with the forth power of distance. This places an upper limit on the distance over which the sensor can be interrogated. Theoretical estimates show that these sensors can be interrogated with sufficient signal-to-noise ratio at distances exceeding 10 m for radiated powers of less than 1 mW. We present results for a strain sensor and a displacement sensor that can be interrogated at a distance of 8 m with a strain resolution of less than 10 ppm and displacement resolution of 0.01 mm, respectively.
Open Access
Computational Procedures for a Class of GI/D/k Systems in Discrete Time
(2009-11-5) Rahman, Md. Mostafizur; Alfa, Attahiru Sule
A class of discrete time GI/D/ systems is considered for which the interarrival times have finite support and customers are served in first-in first-out (FIFO) order. The system is formulated as a single server queue with new general independent interarrival times and constant service duration by assuming cyclic assignment of customers to the identical servers. Then the queue length is set up as a quasi-birth-death (QBD) type Markov chain. It is shown that this transformed GI/D/1 system has special structures which make the computation of the matrix R simple and efficient, thereby reducing the number of multiplications in each iteration significantly. As a result we were able to keep the computation time very low. Moreover, use of the resulting structural properties makes the computation of the distribution of queue length of the transformed system efficient. The computation of the distribution of waiting time is also shown to be simple by exploiting the special structures.
Open Access
Statistical Development of a Duty Cycle for Plug-in Vehicles in a North American Urban Setting Using Fleet Information
(2010) Shahidinejad, Soheil; Bibeau, Eric; Filizadeh, Shaahin
Development of a daily duty cycle based on real world driving behavior and parking times is a critical requirement in the optimal design of power-train components of a plug-in vehicle. Standard driving cycles cannot completely emulate the real-world power demand of a vehicle and its downtimes in particular. To address these shortcomings, a large database of one year of measured data collected from a fleet of 76 cars in the city of Winnipeg, MB, Canada is obtained and is then used to develop a new duty cycle. This paper describes a methodology for statistical analysis of the fleet data, including while a vehicle is parked. Due to the intrinsic differences in vehicle usage profiles during weekdays and weekends, two 24-h duty cycles with suitable windows of opportunity for charging are developed for weekday and weekend driving patterns. The uniqueness of the proposed statistical methodology and the resulting duty cycles contribute to addressing the present shortcomings of standard driving cycles.
Open Access
Histology of the Larval Neodiprion abietis (Hymenoptera: Diprionidae) Digestive Tract
(2011-12-18) Lucarotti, Christopher J.; Whittome-Waygood, Beatrixe H.; Levin, David B.
The alimentary canal of Neodiprion abietis larvae is a straight tube divided into foregut, midgut, and hindgut. Posterior to the mouth, the foregut is further divided into the pharynx, esophagus (crop), and proventriculus, all of which are lined with cuticle. A pair of muscular, chitin-lined pouches branch off the anterior foregut and lie lateral to the alimentary canal. Gastric caeca are located at the anterior end of the midgut, where the peritrophic membrane is formed and was observed throughout the midgut. A single layer of midgut columnar epithelial cells abuts on the basal lamina at one end with microvilli extending into the gut lumen at the other. Nidi of regenerative cells were observed between columnar epithelial cells at the basal lamina. Malpighian tubules are attached to the posterior end of the midgut. The hindgut consists of the pylorus, a muscular ileum connecting to a bulbous rectum, which then opens to the anus.Erratum to “Histology of the Larval Neodiprion abietis (Hymenoptera: Diprionidae) Digestive Tract”
Open Access
Decoding of Turbo Codes in Symmetric Alpha-Stable Noise
(2011-3-29) Shafieipour, Mohammad; Lim, Heng-Siong; Chuah, Teong-Chee
This paper investigates the decoding of turbo codes in impulsive symmetric α-stable (SαS) noise. Due to the nonexistence of a closed-form expression for the probability density function (pdf) of α-stable processes, numerical-based SαS pdf is used to derive branch transition probability (btp) for the maximum a posteriori turbo decoder. Results show that in Gaussian noise, the turbo decoder achieves similar performance using both the conventional and the proposed btps, but in impulsive channels, the turbo decoder with the proposed btp substantially outperforms the turbo decoder utilizing the conventional btp. Results also confirm that the turbo decoder incorporating the proposed btp outperforms the existing Cauchy-based turbo decoder in non-Cauchy impulsive noise, while the two decoders accomplish similar performance in Cauchy noise.
Open Access
Arthritic Hand-Finger Movement Similarity Measurements: Tolerance Near Set Approach
(2011-4-5) Henry, Christopher; Peters, James F.
The problem considered in this paper is how to measure the degree of resemblance between nonarthritic and arthritic hand movements during rehabilitation exercise. The solution to this problem stems from recent work on a tolerance space view of digital images and the introduction of image resemblance measures. The motivation for this work is both to quantify and to visualize differences between hand-finger movements in an effort to provide clinicians and physicians with indications of the efficacy of the prescribed rehabilitation exercise. The more recent introduction of tolerance near sets has led to a useful approach for measuring the similarity of sets of objects and their application to the problem of classifying image sequences extracted from videos showing finger-hand movement during rehabilitation exercise. The approach to measuring the resemblance between hand movement images introduced in this paper is based on an application of the well-known Hausdorff distance measure and a tolerance nearness measure. The contribution of this paper is an approach to measuring as well as visualizing the degree of separation between images in arthritic and nonarthritic hand-finger motion videos captured during rehabilitation exercise.
Open Access
Analysis of wind speed data and wind energy potential in three selected locations in south-east Nigeria
(2012-05-25) Oyedepo, Sunday O; Adaramola, Muyiwa S; Paul, Samuel S
Abstract In this study, the wind speed characteristics and energy potential in three selected locations in the southeastern part of Nigeria were investigated using wind speed data that span between 24 and 37 years and measured at a height of 10 m. It was shown that the annual mean wind speed at a height of 10 m for Enugu, Owerri and Onitsha are 5.42, 3.36 and 3.59 m/s, respectively, while the annual mean power densities are 96.98, 23.23 and 28.34 W/m2, respectively. It was further shown that the mean annual value of the most probable wind speed are 5.47, 3.72 and 3.50 m/s for Enugu, Owerri and Onitsha, respectively, while the respective annual value of the wind speed carrying maximum energy are 6.48, 4.33 and 3.90 m/s. The performance of selected commercial wind turbine models (with rated power between 50 and 1,000 kW) designed for electricity generation and a windmill (rated power, 0.36 kW) for water pumping located in these sites was examined. The annual energy output and capacity factor for these turbines, as well as the water produced by the windmill, were determined. The minimum required design parameters for a wind turbine to be a viable option for electricity generation in each location are also suggested.
Open Access
Pathology of a Gammabaculovirus in Its Natural Balsam Fir Sawfly (Neodiprion abietis) Host
(2012-11-22) Lucarotti, Christopher J.; Whittome-Waygood, Beatrixe H.; Lapointe, Renée; Morin, Benoit; Levin, David B.
The Neodiprion abietis Gammabaculovirus (Baculoviridae: NeabNPV) is virulent, highly contagious, and infects only midgut epithelial cells of balsam fir sawfly larvae, but infections can carry through to adult sawflies in the midgut. Larval infections are characterized by hypertrophy of midgut epithelial cell nuclei, where virogenic stromata develop to produce nucleocapsids that are singly enveloped before occlusion into occlusion bodies. Infected, occlusion body-laden cells slough from the midgut epithelium as a result of a dissolution of the basal lamina. Infected cells undergo lysis, and viral occlusion bodies exit affected larvae in a watery diarrhea to infect other balsam fir sawfly larvae. A budded virus stage was not observed, but nucleocapsid and occlusion body formation resembled the development of occlusion-derived virions and occlusion bodies in lepidopteran alphabaculoviruses.
Open Access
Linking genome content to biofuel production yields: a meta-analysis of major catabolic pathways among select H2 and ethanol-producing bacteria
(2012-12-18) Carere, Carlo R; Rydzak, Thomas; Verbeke, Tobin J; Cicek, Nazim; Levin, David B; Sparling, Richard
Abstract Background Fermentative bacteria offer the potential to convert lignocellulosic waste-streams into biofuels such as hydrogen (H2) and ethanol. Current fermentative H2 and ethanol yields, however, are below theoretical maxima, vary greatly among organisms, and depend on the extent of metabolic pathways utilized. For fermentative H2 and/or ethanol production to become practical, biofuel yields must be increased. We performed a comparative meta-analysis of (i) reported end-product yields, and (ii) genes encoding pyruvate metabolism and end-product synthesis pathways to identify suitable biomarkers for screening a microorganism’s potential of H2 and/or ethanol production, and to identify targets for metabolic engineering to improve biofuel yields. Our interest in H2 and/or ethanol optimization restricted our meta-analysis to organisms with sequenced genomes and limited branched end-product pathways. These included members of the Firmicutes, Euryarchaeota, and Thermotogae. Results Bioinformatic analysis revealed that the absence of genes encoding acetaldehyde dehydrogenase and bifunctional acetaldehyde/alcohol dehydrogenase (AdhE) in Caldicellulosiruptor, Thermococcus, Pyrococcus, and Thermotoga species coincide with high H2 yields and low ethanol production. Organisms containing genes (or activities) for both ethanol and H2 synthesis pathways (i.e. Caldanaerobacter subterraneus subsp. tengcongensis, Ethanoligenens harbinense, and Clostridium species) had relatively uniform mixed product patterns. The absence of hydrogenases in Geobacillus and Bacillus species did not confer high ethanol production, but rather high lactate production. Only Thermoanaerobacter pseudethanolicus produced relatively high ethanol and low H2 yields. This may be attributed to the presence of genes encoding proteins that promote NADH production. Lactate dehydrogenase and pyruvate:formate lyase are not conducive for ethanol and/or H2 production. While the type(s) of encoded hydrogenases appear to have little impact on H2 production in organisms that do not encode ethanol producing pathways, they do influence reduced end-product yields in those that do. Conclusions Here we show that composition of genes encoding pathways involved in pyruvate catabolism and end-product synthesis pathways can be used to approximate potential end-product distribution patterns. We have identified a number of genetic biomarkers for streamlining ethanol and H2 producing capabilities. By linking genome content, reaction thermodynamics, and end-product yields, we offer potential targets for optimization of either ethanol or H2 yields through metabolic engineering.
Open Access
An Investigation into the Response of GFRP-Reinforced Glue-Laminated Tudor Arches
(2012-5-15) Alshurafa, S.; Alhayek, H.; Taheri, F.
This paper presents the results of an experimental and computational investigation tailored to examine the response of glass fiber-reinforced-plastic-(GFRP-) reinforced glue-laminated curved beams and arches. The main objective was to ascertain the viability of GFRP as an effective reinforcement for enhancing the load carrying capacity and stiffness of such curved structures. The study included optimization of the length and thickness of the GFRP reinforcement. In doing so, first a parametric finite element study was conducted to evaluate the influence of unidirectional GFRP reinforcement applied onto the arch using eleven possible configurations and different thicknesses. Subsequently, an experimental investigation was conducted to verify the results established by the finite element method as well as the integrity of actual GFRP-reinforced glue-laminated curved structures. The results indicate that GFRP can be considered as an effective and economically viable solution for strengthening and stiffening glulam arches, without adding any appreciable weight to the structure.
Open Access
Extracting Data from Disparate Sources for Agent-Based Disease Spread Models
(2012-6-21) Laskowski, M.; Demianyk, B. C. P.; Benavides, J.; Friesen, M. R.; McLeod, R. D.; Mukhi, S. N.; Crowley, M.
This paper presents a review and evaluation of real data sources relative to their role and applicability in an agent-based model (ABM) simulating respiratory infection spread a large geographic area. The ABM is a spatial-temporal model inclusive of behavior and interaction patterns between individual agents. The agent behaviours in the model (movements and interactions) are fed by census/demographic data, integrated with real data from a telecommunication service provider (cellular records), traffic survey data, as well as person-person contact data obtained via a custom 3G smartphone application that logs Bluetooth connectivity between devices. Each source provides data of varying type and granularity, thereby enhancing the robustness of the model. The work demonstrates opportunities in data mining and fusion and the role of data in calibrating and validating ABMs. The data become real-world inputs into susceptible-exposed-infected-recovered (SEIR) disease spread models and their variants, thereby building credible and nonintrusive models to qualitatively model public health interventions at the population level.
Open Access
Erratum to “Histology of the Larval Neodiprion abietis (Hymenoptera: Diprionidae) Digestive Tract”
(2012-9-4) Lucarotti, Christopher J.; Whittome-Waygood, Beatrixe H.; Levin, David B.
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Performance of Marine Kinetic Turbine in the Wake
(2013) Birjandi, Amir Hossein; Chatoorgoon, Vijay; Bibeau, Eric
Unlike the uniform and low turbulence conditions of flow in water tunnels and towing tanks, flow in rivers, channels and oceans is highly turbulent and non-uniform due to the eddies with size that exceeds the diameter of the turbine. This condition accentuates in hydrokinetic farm applications where multiple turbines operate in eddies shed behind the upstream turbines. This data set represents the water tunnel test results of non-uniform inflow and upstream vortices on the quality of the output power and the performance of vertical turbines. The non-uniform flow condition is generated by placing cylinders with different sizes upstream of the turbine. The performance characteristics of the turbine operating behind cylinders are compared to that of the turbine operating in uniform inflow. Cylinders with different sizes are placed upstream of the scaled model turbine at various longitudinal and lateral locations. The effect of non-uniform inflow on the average output power and the instantaneous power fluctuations are presented in this Data set.
Open Access
A decoding-based fusion rule for cooperative spectrum sensing with nonorthogonal transmission of local decisions
(2013-07-08) Bokharaiee, Simin; Nguyen, Ha H; Shwedyk, Ed
Abstract Cooperative spectrum sensing in cognitive radio (CR) networks is studied in which each CR performs energy detection to obtain a binary decision on the absence/presence of the primary user. The problem of interest is how to efficiently report and combine the local decisions to/at the fusion center under fading channels. In order to reduce the required transmission bandwidth in the reporting phase, the paper examines nonorthogonal transmission of local decisions by means of on-off keying. Proposed and analyzed is a novel decoding-based fusion rule that essentially performs in three steps: (1) estimating minimum mean-square error of the transmitted information from cognitive radios, (2) making hard decisions of the transmitted bits based on the estimated information, and (3) combining the hard decisions in a linear manner. Simulation results support the theoretical analysis and show that the added complexity of the decoding-based fusion rule leads to a considerable performance gain over the simpler energy-based fusion rule when the reporting links are reasonably strong.
Open Access
Collagen morphology and texture analysis: from statistics to classification
(Nature, 2013-07-12) Mostaço-Guidolin, Leila B.; Ko, Alex C.-T.; Wang, Fei; Xiang, Bo; Hewko, Mark; Tian, Ganghong; Major, Arkady; Shiomi, Masashi; Sowa, Michael G.
In this study we present an image analysis methodology capable of quantifying morphological changes in tissue collagen fibril organization caused by pathological conditions. Texture analysis based on first-order statistics (FOS) and second-order statistics such as gray level co-occurrence matrix (GLCM) was explored to extract second-harmonic generation (SHG) image features that are associated with the structural and biochemical changes of tissue collagen networks. Based on these extracted quantitative parameters, multi-group classification of SHG images was performed. With combined FOS and GLCM texture values, we achieved reliable classification of SHG collagen images acquired from atherosclerosis arteries with >90% accuracy, sensitivity and specificity. The proposed methodology can be applied to a wide range of conditions involving collagen re-modeling, such as in skin disorders, different types of fibrosis and muscular-skeletal diseases affecting ligaments and cartilage.

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