Proceedings of 11th International Conference on Durability of Building Materials and Components: 11 May 2008, Istanbul, Turkey. This paper presents a new hygrothermal model (HAMFit) for simulating the transport of heat, air and moisture across building envelopes. The model is based on partial differential equations solved simultaneously for air velocity, temperature, and moisture distributions for given interior and exterior conditions using finite-element-based commercial software called COMSOL Multiphysics and MatLab. The model is benchmarked using internationally-published numerical model test cases., Conference paper, Published. A version of this document is published in: 11th International Conference on Durability of Building Materials and Components, Istanbul, Turkey, May 11-14, 2008, pp. 1-8.
Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society, Montreal, Quebec, Canada, on 20-23 Sept. 1995. The measurement of pressure at a device/tissue interface is desirable in many biomedical engineering applications such as tourniquets and mammography in order to optimize the design or performance of the device. Testing of a selection of existing interface transducers has demonstrated that many are dependent on device and tissue compliance. Such a transducer is only useful in an application where it has been calibrated for specific device/tissue compliance combinations. To overcome this limitation the authors have developed an interface pressure transducer whose output signal is not affected by changes in interface compliance. This enables the transducer to quantitatively measure pressure in many applications without the need to calibrate the transducer for varying compliance conditions. The signal from such a transducer could be incorporated into a control system to measure and control the pressure applied by a mammography machine to the breast., Conference paper, Published.
Home support workers (HSWs) work in clients’ homes assisting with rehabilitation and activities of daily living. Like all health-care professionals, HSWs are at an increased risk for developing back injuries. Lift devices have been shown to reduce injuries to the worker. Presently, there are few lifting devices for home use that cost under $4000 CDN. Our study involved designing a safe and affordable lift device (retail cost under $2000 CDN) to be used by HSWs in the home and evaluating it in a typical bathroom. Thirty-eight HSWs and three seniors evaluated the BCIT lift, a commercially available lift (BHM Medical Inc.) and the manual method of transfer and lift. Results indicated that the BCIT lift was an improvement over the manual method of transferring, and approximated the more expensive, automatic lift in terms of perceived exertion, ease of use and safety. Feedback provided to the researchers has been incorporated into a new, ergonomically sound and marketable lift device., Peer-reviewed article, Published. Received 1 February 2003, Revised 27 January 2004, Accepted 23 February 2004, Available online 6 May 2004.
The measurement of the interface pressure between a biomedical device and part of the human body is useful to aid in the design or improve the performance and safety of such devices. Therefore, a need exists for a transducer to measure interface pressure in these applications. The development and evaluation of an interface pressure transducer was the main goal of this research. Surgical retraction, surgical tourniquets and mammography were selected as demonstration applications for the developed transducer. These target applications were selected because they represented a wide spectrum of device and tissue characteristics and properties, and were in common use. A review of the available clinical, commercial and engineering literature identified a wide range of transducers and transducer technologies used for interface pressure measurement. The transducers included pneumatic/hydraulic, fibre-optic, strain based, capacitive and micromachined technologies. No standard method of measuring interface pressure was described and, in many cases, investigators cautioned against comparing-interface pressure measurements obtained using different measurement systems. From this review and an examination of the biomedical applications mentioned, the design criteria and optimal design specifications for an interface pressure transducer were defined. To gain a better understanding of the mechanical response of the interface between a device, transducer, and tissue to an applied loading, a preliminary finite element model was developed and studied. The model demonstrated the potential for shear stresses to develop between the transducer and interface materials. Furthermore a calibration system which simulated interface conditions was developed to evaluate both existing and developed transducers for use as interface pressure transducers. This evaluation demonstrated the lack of a transducer whose output was independent of the compliance of the interface materials. As well, an essential characteristic was identified for an effective interface pressure transducer that could be used in several applications where the interface material compliance was different. Based on the knowledge gained from the finite element analysis and existing transducer evaluation results, a novel interface pressure transducer was developed and evaluated both in the calibration system and via demonstration applications of surgical retraction and tourniquets. Under laboratory conditions in the calibration system, the transducer met many of the desired design specifications. The transducer was tested in the lab under both pneumatic and nonpneumatic tourniquet cuffs. The transducer worked well under the pneumatic cuff but required ] further development for use under the non-pneumatic cuff. The transducer was also integrated into a surgical retractor and evaluated in five clinical trials. It met many of the desired specifications for this application., Thesis, Published.
Proceedings of 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Milan, Italy, Aug 25-29 2015. "Dynamic wheeled mobility" offers "on the fly" seating adjustments for wheelchair users such that various activities performed throughout the day can be matched by an appropriate seat position. While this has benefits for user participation and health, the added weight in existing dynamic wheelchairs may impact the user's ability to transport the frame, e.g. into cars. Other dynamic features to enable more participation avenues are also desirable. This paper outlines the development of a "kneeling" ultralight wheelchair design that offers dynamic wheeled mobility functionality at a weight that is comparable to many existing ultralight wheelchairs. In addition, the wheelchair's kneeling function allows a lowered seat position to facilitate low-to-the-ground tasks such as floor transfers and other activities where sustained low level reaching may be required (e.g. playing with children, changing a tire, etc.). This paper also describes the development and pilot testing of an end user evaluation protocol designed to validate the wheelchair's functionality and performance. Successful realization and commercialization of the technology would offer a novel product choice for people with mobility disabilities, and that may support daily activities, health, improved quality of life, and greater participation in the community., Conference paper, Published.
Use of any recycled material helps to maintain a greener environment by keeping waste materials out of the landfills. Recycling practices also can decrease the environmental and economical impact of manufacturing the materials from virgin resources, which reduces the overall carbon footprint of industrial materials and processes. This study examined the use of waste materials such as crushed glass, ground tire rubber, and recycled aggregate in concrete. Compressive strength and elastic modulus were the primary parameters of interest. Results demonstrated that ground tire rubber introduced significant amounts of air into the mix and adversely affected the strength. The introduction of a defoamer was able to successfully remove part of the excess air from the mix, but the proportional strength improvements were not noted implying that air left in the defoamed mixture had undesirable characteristics. Freeze-thaw tests were next performed to understand the nature of air in the defoamed mixtures, and results demonstrated that this air is not helpful in resisting freeze-thaw resistance either. Overall, while lightweight, low-carbon footprint concrete materials seem possible from recycled materials, significant further optimization remains possible., Peer-reviewed article, Published. Received 4 April 2011; Revised 27 July 2011; Accepted 27 July 2011.
Proceedings of 1996 Canadian Conference on Electrical and Computer Engineering, Calgary, Alberta on 26-29 May 1996. In many medical situations, the need for measuring the pressure applied to a tissue quickly and accurately is crucial. Most conventional devices do not measure the actual pressure applied to the tissue because they do not compensate for the tissue or device compliance characteristics and need to be calibrated for each measurement environment. Neuromuscular damage may occur if too much pressure is applied to a tissue for an extended period of time in applications such as tourniquet systems. Incorrect diagnosis may occur if too little pressure is applied in applications such as mammography units. A compliance-independent pressure transducer has other biomedical applications in surgical retraction devices and prosthetic sockets. To eliminate the compliance problem, a pressure transducer was developed using bulk micromachining technology., Conference paper, Published.
Purpose: Stairways into buildings present a significant environmental barrier for those with mobility impairments. A number of home access solutions that allow users to safely enter and exit the home exist; however, these all have some limitations. The purpose of this work was to develop a novel, inclusive home access solution that integrates a staircase and a lift into one device.
Method: We developed an integrated staircase lift following a structured protocol with stakeholders providing feedback at various stages in the design process, consistent with rehabilitation engineering design methods.
Results: A novel home access device was developed. The integrated staircase-lift has the following features: inclusivity, by a design that provides an option for either use of stairs or a lift; constant availability, with a lift platform always ready for use on either level; and potential aesthetic advantages when integrating the device into an existing home. The potential also exists for emergency descent during a power outage, and self-powered versions.
Conclusions: By engaging stakeholders in a user-centred design process, we were able to gain insight into the limitations of existing home access solutions and get specific feedback on our lift concept. This information strengthened the development of a novel home access device., Peer-reviewed article, Published. Article first published online: July 16, 2015; Issue published: October 26, 2015.
Proceedings of the Rehabilitation Engineering and Assistive Technology Society of North America Annual Conference 2011. The Elevation™ wheelchair was recently developed and introduced to the market as an alternative to conventional ultralight rigid wheelchairs normally used by paraplegics and others with disabilities necessitating the daily use of a manual wheelchair. The Elevation wheelchair provides independent user-adjustable seat positioning during normal usage. Elevation allows the user to quickly and easily adjust in real-time the seat height, as well as backrest recline angle, all in a manual ultralight rigid wheelchair form factor. This allows for dynamic seat positioning to suit the tasks and comfort of users throughout their daily activities. The rationale for and user-driven development of the Elevation wheelchair is summarized here., Conference paper, Published.
This paper presents a two stage model of negligence and legal action. In the first stage the defendant decides on the level of due care to take while carrying out an action or activity. In the second stage an accident has occurred and the plaintiff brings suit. Lawyers (agents) invest in actions that are designed to increase the probability of success on behalf of their respective clients. First we present the symmetric casewhere all decisions on investment in legal services occur ex-post (after an accident has occured). We then look as the case where the potential injurer pre-commits to a level of legal services ex-ante (prior to an accident) and analyze the effect that pre-commitment in legal services has on the stage one choice of care. We then present a case study from the field of labour relations where strategic pre-commitment is used to influence the settlement of grievances. The grievance process in labour relations parallel civil litigation and a grievance can be viewed as equivalent to either a tort or a breach of contract; depending on the type of grievance., Essay, Published.
This paper extends the work of Mathewson and Winter (1985) in the field of franchising. Given the hypothesis that a franchise contract ensures quality compliance at a lower cost relative to alternative organizational structures, the existence of dual organizational structures within the same franchise chain is inadequately explained. This paper extends the basic model of Mathewson and Winter into a spatial framework, demonstrating that nonconvexities in monitoring costs will produce dual organizational structures within the same chain., Essay, Published.
With their continuous growth, understanding how plant shapes form is fundamentally linked to understanding how growth rates are controlled across different regions of the plant. Much of a plant's architecture is generated in shoots and roots, where fast growth in tips contrasts with slow growth in supporting stalks. Shapes can be determined by where the boundaries between fast- and slow-growing regions are positioned, determining whether tips elongate, branch, or cease to grow. Across plants, there is a diversity in the cell wall chemistry through which growth operates. However, prototypical morphologies, such as tip growth and branching, suggest there are common dynamic constraints in localizing chemical growth catalysts. We have used Turing-type reaction-diffusion mechanisms to model this spatial localization and the resulting growth trajectories, characterizing the chemistry-growth feedback necessary for maintaining tip growth and for inducing branching. The mechanism defining the boundaries between fast- and slow-growing regions not only affects tip shape, it must be able to form new boundaries when the pattern-forming dynamics break symmetry, for instance in the branching of a tip. In previous work, we used an arbitrary concentration threshold to switch between two dynamic regimes of the growth catalyst in order to define growth boundaries. Here, we present a chemical dynamic basis for this threshold, in which feedback between two pattern-forming mechanisms controls the extent of the regions in which fast growth occurs. This provides a general self-contained mechanism for growth control in plant morphogenesis (not relying on external cues) which can account for both simple tip extension and symmetry-breaking branching phenomena., Peer-reviewed article, Published. Received 7 December 2011, Revised 6 March 2012, Accepted 21 March 2012, Available online 28 March 2012.