Research

  • 15729
  • 0
  • A Study of High Frequency Ultrasound Scattering from Non-nucleated Biological Specimens
    A Study of High Frequency Ultrasound Scattering from Non-nucleated Biological Specimens
    Online version of an article originally published as: A study of high frequency ultrasound scattering from non-nucleated biological specimens. Omar Falou, Ralph E. Baddour, George Nathanael, Gregory J. Czarnota, J. Carl Kumaradas and Michael C. Kolios (2008) The Journal of the Acoustical Society of America, 124(5): EL278-EL283 Publisher URL: http://dx.doi.org/10.1121/1.2987462
    A Systems Perspective on Volunteered Geographic Information
    A Systems Perspective on Volunteered Geographic Information
    A novel and diverse type of geographic information, volunteered geographic information (VGI) is proving to be more than just a new type of data. In an effort to contribute to the conceptualization of the burgeoning field of VGI research, we propose to review selected definitions and debates around Geographic Information Systems (GIS). Traditional geographic information emerges from the interplay of the components of GIS: hardware, software, data, and people. It is shaped by the processing of geographic data through a series of functions for input, management, analysis, and presentation. Consequently, we suggest framing VGI as the information product originating from a "VGI system". The systems perspective takes into account the hardware and software used to set up a VGI initiative; the characteristics of the data volunteered by users; and the application context including the people involved in purposefully creating VGI as the system output. For example, VGI in citizen science emerges from numerical measurements (e.g., private weather stations) or categorical user input (e.g., invasive species observations), while VGI in map-based discussion forums comes from text input or multimedia submissions. In fact, VGI is only "voluntary" in that it is the result of sourcing and processing volunteered geographic data. Taking this broader perspective of VGI as the output of a system will allow us to better understand different types of VGI and the functionality needed to create them. It offers a comprehensive methodology for research into VGI. Ultimately, we may be able to design more effective systems for successful VGI initiatives., The presentation is attached - click download link to access PDF file.
    A Systems View of Bioinspiration: Bridging the Gaps
    A Systems View of Bioinspiration: Bridging the Gaps
    This paper provides an overview of biom*, an umbrella term for biomimicry, biomimetics, bio-inspired design and related fields. The paper explores three levels of biom* bridging, discusses benefits and implications of adopting a systems perspective, and proposes initiatives for further development. Searching for ‘sweet spots’ leveraging the synergy between aspiration, our growing knowledge of natural systems, and the market economy will improve the ability of biom* to deliver meaningful and impactful solutions.
    A Tale of Two Motives: Endogenous Time Preference, Cash-in-Advance Constraints and Monetary Policy
    A Tale of Two Motives: Endogenous Time Preference, Cash-in-Advance Constraints and Monetary Policy
    This paper demonstrates the effects of modeling an endogenous rate of time preference and two cash-in-advance constraints. If the constraint is levied on consumption and capital goods, time preference effects are neutral and cash-in-advance constraint effects invert the Tobin Effect. If the constraint applies solely to consumption goods, opposing motives are offsetting and monetary policy is super neutral., Kam, E. (2013). A Tale of Two Motives: Endogenous Time Preference, Cash-in-Advance Constraints and Monetary Policy. ME, 04(06), pp.427-430.
    A Tale of Two Systems: Success and Failure in a Single Information System Implementation
    A Tale of Two Systems: Success and Failure in a Single Information System Implementation
    This paper presents a case study of an information system implementation. The system, a computerized student record system, was introduced into a small university when the university opened. Unlike many other case studies of systems implementation, there was no existing system to replace, thus it was expected that there would be little resistance to the system. Successful implementation was anticipated, particularly as the systems designers were also the primary users. An evaluation of the system shows this was not the case. Two groups of users are identified, one pleased with the system, the other dissatisfied. The secondary users did not display their dissatisfaction with the system by resistance, however. They used the system frequently, but were denied the full access they required to do their jobs. Ostensibly due to technical limitations of the system, the primary users acted as gatekeepers. An examination of the culture and management structure of the university reveals strong political motivations for the primary users to exert power over the secondary users. Markus’s (1983) interpretation of interaction theory is used to discuss the political implications of the system design. It is concluded that senior management must be aware of the importance of information systems to their organizations, and understand the potential for designers to use these systems as sources of power. The case study is reconstructed from the author’s experiences as a staff member at the university during the system implementation, initially as a primary user of the system (but not an active member of the system design team), and later as a secondary user. The case is evaluated from the perspective of both user groups, using a framework derived from the literature on information systems failure and successful systems implementation., Middleton, Catherine. (1995). A Tale of Two Systems: Success and Failure in a Single Information System Implementation. (Working Paper 20-97). North York, ON: OBIR/Schulich School of Business.
    A Techno-economic Analysis of Heat-Pump Entering Fluid Temperatures, and CO2 Emissions for Hybrid Ground Source Heat Pump Systems
    A Techno-economic Analysis of Heat-Pump Entering Fluid Temperatures, and CO2 Emissions for Hybrid Ground Source Heat Pump Systems
    Hybrid ground-source heat pumps (GSHPs) that include a ground loop for the base heating and cooling needs, and an auxiliary system (natural gas boiler and electric air conditioner) for peak loads, are an economical and environmentally cleaner alternative to conventional systems. For a ground-source heat pump (GSHP) system, the choice of entering fluid temperature (EFT) to the heat pump plays a crucial role in determining system efficiency of and operating costs. To continue expanding the knowledge base of efficiently sizing GSHPs as a component of a hybrid system, this study explores the economic effects of choosing an EFT for a heat pump. In addition, system CO2 emissions are calculated and analyzed for a variety of building types. Using a computational approach to size hybrid GSHP systems recently published in [Alavy et al., Renewable Energy, 57 (2013) 404-412], the effects of optimizing EFT for a heat pump, and CO2 emissions were studied for a variety of commercial installations. In the present study, using ten buildings situated in Southern Ontario, Canada, by varying cooling and heating EFTs for a heat pump, savings ranging from 0.47% to 3.6% can be achieved compared to using a fixed EFT pairfor a heat pump. In addition, comparisons were made between the CO2 emissions of optimally sized (based on economic factors) hybrid GHSPs and those of non-hybridized GSHPs. Both the optimally-sized hybrid GHSPs, and the non-hybridized GSHPs significantly reduce CO2 emissions compared to the use of conventional natural gas/electrical systems. The additional environmental benefit of the non-hybridized GSHPs over that of the optimally-sized hybrid GSHPs was found to be negligible in most cases analyzed., Nguyen, H. V., Law, X. E., Zhou, X., Leong, W. H., & Dworkin, S. B. (2016). A techno-economic analysis of heat-pump entering fluid temperatures and CO2 emissions for hybrid ground source heat pump systems. Geothermics, 61, 24-34. doi:10.1016/j.geothermics.2016.01.013
    A Trade Policy Perspective On Import Quotas And The Substitution Effect
    A Trade Policy Perspective On Import Quotas And The Substitution Effect
    This paper focuses on the necessary conditions required in order to exploit the substitution effect which arises when there is a shift in demand induced by import quotas under imperfect competition. The protective policy succeeds if the substitution effect shifts in favor of goods produced by the domestic industry and this shift offsets foreign firms quota rents and the decrease in consumer welfare. While extant literature tends to focus on welfare loss associated with import quotas, in this paper social welfare analytics are produced and a trade policy decision rule for net welfare gain is obtained.
    A Unified Model for the Prediction of Yield Strength in Particulate-Reinforced Metal Matrix Nanocomposites
    A Unified Model for the Prediction of Yield Strength in Particulate-Reinforced Metal Matrix Nanocomposites
    Lightweighting in the transportation industry is today recognized as one of the most important strategies to improve fuel efficiency and reduce anthropogenic climate-changing, environment-damaging, and human death-causing emissions. However, the structural applications of lightweight alloys are often limited by some inherent deficiencies such as low stiffness, high wear rate and inferior strength. These properties could be effectively enhanced by the addition of stronger and stiffer reinforcements, especially nano-sized particles, into metal matrix to form composites. In most cases three common strengthening mechanisms (load-bearing effect, mismatch of coefficients of thermal expansion, and Orowan strengthening) have been considered to predict the yield strength of metal matrix nanocomposites (MMNCs). This study was aimed at developing a unified model by taking into account the matrix grain size and porosity (which is unavoidable in the materials processing such as casting and powder metallurgy) in the prediction of the yield strength of MMNCs. The Zener pinning effect of grain boundaries by the nano-sized particles has also been integrated. The model was validated using the experimental data of magnesium- and titanium-based nanocomposites containing different types of nano-sized particles (namely, Al2O3, Y2O3, and carbon nanotubes). The predicted results were observed to be in good agreement with the experimental data reported in the literature., Mirza, F. A., & Chen, D. L. (2015). A unified model for the prediction of yield strength in particulate-reinforced metal matrix nanocomposites. Materials, 8(8), 5138-5153. doi:10.3390/ma8085138, (This article belongs to the Section Advanced Composites)
    A biomechanical assessment of modular and monoblock revision hip implants using FE analysis and strain gage measurements
    A biomechanical assessment of modular and monoblock revision hip implants using FE analysis and strain gage measurements
    Background The bone loss associated with revision surgery or pathology has been the impetus for developing modular revision total hip prostheses. Few studies have assessed these modular implants quantitatively from a mechanical standpoint.Methods Three-dimensional finite element (FE) models were developed to mimic a hip implant alone (Construct A) and a hip implant-femur configuration (Construct B). Bonded contact was assumed for all interfaces to simulate long-term bony ongrowth and stability. The hip implants modeled were a Modular stem having two interlocking parts (Zimmer Modular Revision Hip System, Zimmer, Warsaw, IN, USA) and a Monoblock stem made from a single piece of material (Stryker Restoration HA Hip System, Stryker, Mahwah, NJ, USA). Axial loads of 700 and 2000 N were applied to Construct A and 2000 N to Construct B models. Stiffness, strain, and stress were computed. Mechanical tests using axial loads were used for Construct A to validate the FE model. Strain gages were placed along the medial and lateral side of the hip implants at 8 locations to measure axial strain distribution.Results There was approximately a 3% average difference between FE and experimental strains for Construct A at all locations for the Modular implant and in the proximal region for the Monoblock implant. FE results for Construct B showed that both implants carried the majority (Modular, 76%; Monoblock, 66%) of the 2000 N load relative to the femur. FE analysis and experiments demonstrated that the Modular implant was 3 to 4.5 times mechanically stiffer than the Monoblock due primarily to geometric differences.Conclusions This study provides mechanical characteristics of revision hip implants at sub-clinical axial loads as an initial predictor of potential failure., Journal of Orthopaedic Surgery and Research 2010, 5:34. doi:10.1186/1749-799X-5-34
    A changing landscape in collection development
    A changing landscape in collection development
    Ryerson University Library has been exploring different just-in-time acquisition models that provide us with cost-effective ways to purchase monograph titles with guaranteed usage. Based on our experience with Ebrary on the PDA (Patron Driven Acquisitions) Pilot, and with YBP on the DDA (Demand Driven Acquisitions) project, this discussion will focus on the theory behind our approach, the technicalities of implementation, and implications for future collection development strategies.
    A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity
    A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity
    A numerical study is conducted of methane-air coflow diffusion flames at microgravity (μg) and normal gravity (lg), and comparisons are made with experimental data in the literature. The model employed uses a detailed gas phase chemical kinetic mechanism that includes PAH formation and growth, and is coupled to a sectional soot particle dynamics model. The model is able to accurately predict the trends observed experimentally with reduction of gravity without any tuning of the model for different flames. The microgravity sooting flames were found to have lower temperatures and higher volume fraction than their normal gravity counterparts. In the absence of gravity, the flame radii increase due to elimination of buoyance forces and reduction of flow velocity, which is consistent with experimental observations. Soot formation along the wings is seen to be surface growth dominated, while PAH condensation plays a more major role on centerline soot formation. Surface growth and PAH growth increase in microgravity primarily due to increases in the residence time inside the flame. The rate of increase of surface growth is more significant compared to PAH growth, which causes soot distribution to shift from the centerline of the flame to the wings in microgravity. Keywords: laminar diffusion flame,methane-air,microgravity, soot formation, numerical modelling, Veshkini, R., & Dworkin, S. B. (2017). A computational study of soot formation and flame structure of coflow laminar methane/air diffusion flames under microgravity and normal gravity. Combustion Theory and Modelling. http://dx.doi.org/10.1080/13647830.2017.1308558
    A hybrid method to design and optimize a battery closed-loop supply chain:  multi-objective approach
    A hybrid method to design and optimize a battery closed-loop supply chain: multi-objective approach
    There are a variety of prominent factors associated with total expected profit of a closed-loop supply chain (CLSC). In a forward flow, volatility in transportation cost, inventory cost, and forecasting the market’s demand are the most challenging issues for decision makers, while determining the rate of returned products and efficiency in recycling the returned products are crucial parameters to predict in reverse flow. In this thesis, it is aimed to develop and apply mixed-integer linear programming (MILP), scenario-based analysis, and fully fuzzy programming (FFP) methods to maximize the profit for a multi-echelon, multi-components, multi-product, multi-period battery CLSC in Vancouver, Canada. Furthermore, the proposed model is extended to multi-objective to consider the green factors related to plants and battery recovery centers. Fuzzy analytic network process (Fuzzy ANP) is utilized to convert the qualitative factors to the measurable parameters. Then, distance technique and ℇ-constraint method are utilized for solving the multi-objective problem.