BCIT Citations Collection | BCIT Institutional Repository

BCIT Citations Collection

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Collection of published works from BCIT researchers, faculty, and instructors.

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Assessment of natural ventilation effectiveness for an active NetZero energy house
This study was undertaken to investigate the effectiveness of an integrated natural ventilation design for a NetZero energy house in maintaining occupants comfortable solely by passive means. The house was instrumented and monitored during the warmest months of the year. A dynamic thermal model and a computational fluid dynamics (CFD) model were developed to supplement the measurements and help to understand the factors that contribute to the effectiveness of the design. A methodology was developed to validate the models with data and cross-validate them. Adaptive thermal comfort is used as the metric to determine if comfort has been achieved. The study concludes that the house as a whole meets the comfort target. Two technologies were compared through simulations to evaluate their effect on enhancing wind-induced natural ventilation. The technologies did not improve cooling performance in a significant manner. Further work is needed to improve the models through technologies testing in the laboratory and model the uncertainty of the boundary forces to increase confidence in the results., Peer reviewed, Peer reviewed article, Published online: 06 Sep 2016., Adaptive thermal comfort, Natural ventilation, Active house, NetZero energy house
Assessment of thermal comfort during surgical operations
The thermal environment was studied in two operating rooms at the Montreal General Hospital. Thermal comfort of the staff was assessed based on measurements of the environment during surgical operations and on questionnaires given to the staff. Infrared pictures of representative surfaces and people were also taken and, when possible, skin and core temperatures of the patient were also measured. The thermal resistance of clothing and the activity levels for all the people were estimated from published tables and previous research studies. Three thermal zones were studied: zone 1, bounded by the patient, the surgical staff, and the surgical lights; zone 2, the adjacent area; and zone 3, the farthest one. It was found that under the present environmental and personal conditions it is not possible to provide all groups of people with an acceptable thermal environment. In general, surgeons tend to feel from slightly warm to hot (they sweat very often), anesthesia staff and nurses from slightly cool to cold, and the patient from slightly cool to very cold (patients sometimes woke up shivering). In addition to questionnaires, thermal comfort was predicted based on Fanger ' PMV model, which assumes a uniform thermal environment. Based on Fanger's model, the air temperature that could have ensured satisfactory thermal comfort for the surgeon, under the particular conditions studied, was about 66 deg F (19 deg C). However, at that temperature, to remain in good thermal comfort, nurses and anesthetists must be clothed with at least 0.9 clo and the patient covered with at least 1.6 clo. In practice, however, the radiant temperature asymmetry from the surgical lights in zone 1, which ranges between 11 deg F (6 deg C) and 137 (7 deg C) over the operating table and between 18 deg F (1O deg C) and 22F (12 deg C) over the floor (at a level of 1.1 m), causes surgeons' dissatisfaction with the environment at any air temperature. Possible solutions to minimize radiation and its effects on the surgeons are discussed, which would permit ambient temperatures more favorable for the patient and all the staff., Peer reviewed, Conference proceeding, Published: 2001.
Attic baffle size and vent configuration impacts on attic ventilation
The international residential code (IRC) and most building codes in North America provide attic ventilation codes which allow a certain minimum venting area with an unblocked space by the ceiling insulation. Most of these codes have similar minimum venting ratio, minimum space gap between the roof sheathing and ceiling insulation and vent area location for similar climatic conditions. In this paper, the effects of varying the gap between roof sheathing and ceiling insulation (baffle size) and the locations of vent area under both summer and winter conditions are investigated. Three different baffle sizes and three different locations of the attic vent are used to study their effect on the air distribution and temperature profile inside the attic space. A CFD model is developed and validated using existing experimental measurements. Results show that increasing baffle size hugely affects the air distribution when the air flow is majorly driven by wind. The upper side roof vents have been located at three different locations and our findings show when the upper vent is placed the furthest from the ridge the Air Change per Hour (ACH) value in the attic increases but the air circulation is minimal in the top parts of the attic space and structural elements., Peer-reviewed article, Published. Received 29 November 2014, Revised 26 January 2015, Accepted 28 January 2015, Available online 7 February 2015.
Belief change with uncertain action histories
We consider the iterated belief change that occurs following an alternating sequence of actions and observations. At each instant, an agent has beliefs about the actions that have occurred as well as beliefs about the resulting state of the world. We represent such problems by a sequence of ranking functions, so an agent assigns a quantitative plausibility value to every action and every state at each point in time. The resulting formalism is able to represent fallible belief, erroneous perception, exogenous actions, and failed actions. We illustrate that our framework is a generalization of several existing approaches to belief change, and it appropriately captures the non-elementary interaction between belief update and belief revision., Peer-reviewed article, Published.
Belief manipulation and message meaning for protocol analysis
Agents often try to convince others to hold certain beliefs. In fact, many network security attacks can actually be framed in terms of a dishonest that is trying to get an honest agent to believe some particular, untrue claims. While the study of belief change is an established area of research in Artificial Intelligence, there has been comparatively little exploration of the way one agent can explicitly manipulate the beliefs of another. In this paper, we introduce a precise, formal notion of a belief manipulation problem. We also illustrate that the meaning of a message can be parsed into different communicative acts, as defined in discourse analysis theory. Specifically, we suggest that each message can be understood in terms of what it says about the world, what it says about the message history, and what it says about future actions. We demonstrate that this kind of dissection can actually be used to discover the goals of an intruder in a communication session, which is important when determining how an adversary is trying to manipulate the beliefs of an honest agent. This information will then help prevent future attacks. We frame the discussion of belief manipulation primarily in the context of cryptographic protocol analysis., Peer-reviewed article, Published. Received: 17 January 2014; Accepted: 29 September 2014; Published: 10 October 2014.
Biomechanical characteristics, patient preference and activity level with different prosthetic feet
Providing appropriate prosthetic feet to those with limb loss is a complex and subjective process influenced by professional judgment and payer guidelines. This study used a small load cell (Europa™) at the base of the socket to measure the sagittal moments during walking with three objective categories of prosthetic feet in eleven individuals with transtibial limb loss with MFCL K2, K3 and K4 functional levels. Forefoot stiffness and hysteresis characteristics defined the three foot categories: Stiff, Intermediate, and Compliant. Prosthetic feet were randomly assigned and blinded from participants and investigators. After laboratory testing, participants completed one week community wear tests followed by a modified prosthetics evaluation questionnaire to determine if a specific category of prosthetic feet was preferred. The Compliant category of prosthetic feet was preferred by the participants (P=0.025) over the Stiff and Intermediate prosthetic feet, and the Compliant and Intermediate feet had 15% lower maximum sagittal moments during walking in the laboratory (P=0.0011) compared to the Stiff feet. The activity level of the participants did not change significantly with any of the wear tests in the community, suggesting that each foot was evaluated over a similar number of steps, but did not inherently increase activity. This is the first randomized double blind study in which prosthetic users have expressed a preference for a specific biomechanical characteristic of prosthetic feet: those with lower peak sagittal moments were preferred, and specifically preferred on slopes, stairs, uneven terrain, and during turns and maneuvering during real world use., Peer-reviewed article, Published.
Brain-computer interface design for asynchronous control applications
The low-frequency asynchronous switch design (LF-ASD) was introduced as a direct brain-computer interface (BCI) technology for asynchronous control applications. The LF-ASD operates as an asynchronous brain switch (ABS) which is activated only when a user intends control and maintains an inactive state output when the user is not meaning to control the device (i.e., they may be idle, thinking about a problem, or performing some other action). Results from LF-ASD evaluations have shown promise, although the reported error rates are too high for most practical applications. This paper presents the evaluation of four new LF-ASD designs with data collected from individuals with high-level spinal cord injuries and able-bodied subjects. These new designs incorporated electroencephalographic energy normalization and feature space dimensionality reduction. The error characteristics of the new ABS designs were significantly better than the LF-ASD design with true positive rate increases of approximately 33% for false positive rates in the range of 1%-2%. The results demonstrate that the dimensionality of the LF-ASD feature space can be reduced without performance degradation. The results also confirm previous findings that spinal cord-injured subjects can operate ABS designs to the same ability as able-bodied subjects., Peer-reviewed article, Published. Manuscript received June 30, 2003; revised February 6, 2004.
Brain interface research for asynchronous control applications
The Neil Squire Society has developed asynchronous, direct brain switches for self-paced control applications with mean activation rates of 73% and false positive error rates of 2%. This report summarizes our results to date, lessons learned, and current directions, including research into implanted brain interface designs., Peer-reviewed article, Published. Manuscript received July 16, 2005; revised March 15, 2006; March 20, 2006.
The business case for accessible workplaces
The article focuses on the cost-benefit findings for ensuring workplaces are made accessible to disabled employees. Topics discussed include accessibility to workplaces in Canada; determining the financial benefit of built environment accommodations through employee retention; and savings in employee retention and retraining costs., Article, Published.
CAD-CAM applications for spinal orthotics
In the summer of 1988, a joint study was done by the Prosthetics and Orthotics Department at the British Columbia Institute of Technology and the Medical Engineering Resource Unit (MERU) of the University of British Columbia. The study was undertaken to determine the feasibility of applying existing Computer Aided Design-Computer Aided Manufacture (CAD-CAM) techniques to the design and manufacture of spinal orthoses. The orthosis design selected was a TLSO for the treatment of a non-structural curve of the spine. The results of the study were very promising. This paper describes the study and discusses the results., Peer-reviewed article, Published.
A Canada-wide survey of chronic respiratory disease and spinal cord injury
With advances in acute care for individuals with spinal cord injury (SCI), chronic conditions are becoming a central focus.1–3 More specifically, impairments in respiratory function are one of the leading causes of morbidity and mortality among individuals with SCI,4 and have significant economic burden. Paresis or paralysis of the respiratory muscles can lead to respiratory insufficiency, which has a major impact on cough effectiveness and susceptibility to infection.5–7 Prior studies have typically focused on breathing mechanics and pneumonia in the acute stages of SCI, but there is a dearth of evidence regarding secondary chronic conditions, such as asthma and chronic obstructive pulmonary disease (COPD), among SCI populations. In the general population, risk factors for the development of asthma and COPD include genetic, sociodemographic, and environmental components.8,9 In addition, traffic pollution and occupational exposures, and indoor exposure to pollutants such as mold, increase susceptibility to both diseases. However, that SCI may be an independent risk factor for COPD and asthma (or vice versa) has not been previously examined. It thus remains unknown whether there is a higher prevalence of chronic respiratory diseases (after adjustment for potential confounders) in individuals with SCI. The current study addresses this knowledge gap by utilizing the national Canadian Community Health Survey, which comprises comprehensive, up-to-date, cross-sectional data. Our aim was to estimate the prevalence of chronic respiratory outcomes in the SCI population, to compare their odds with a non-SCI population, and to investigate this relationship after controlling for confounders., Peer-reviewed article, Published. Received September 18, 2014; Accepted December 09, 2014.
Carbonation in concrete infrastructure in the context of global climate change
A number of recent studies have identified and begun to quantify increased susceptibility of the infrastructure to climate change–induced carbonation of reinforced concrete. In this paper, the results of a study are presented which uses an updated empirical model to predict the diffusion coefficient of carbon dioxide (CO2) in concrete and thereafter, predict carbonation depths for a number of urban environments in the United States. Data from newer climate forecasts from the 5th Intergovernmental Panel on Climate Change assessment report are used to generate predictions for carbonation depths in four U.S. cities of varying geographic and climatic conditions (Los Angeles, Houston, Chicago, New York City). Results confirm that carbonation depths will increase in the future because of climate change. The magnitude of the increase is dependent on the climate-change scenario considered and the geographic location of the city. Whether or not the increases will require building code changes to increase concrete cover or improve concrete quality will be dependent on actual construction practices for the city in question., Peer-reviewed article, Published. Received: January 05, 2015; Accepted: July 30, 2015; Published online: October 28, 2015.
Carbonation in concrete infrastructure in the context of global climate change
There is nearly unanimous consensus amongst scientists that increasing greenhouse gas emissions, including CO2 generated by human activity, are effecting the Earth’s climate. Increasing atmospheric CO2 emissions will likely increase the rates of carbonation in reinforced concrete structures. However, there is a lack of reliable models to predict the depth of carbonation as a function of time. To address this deficiency, a numerical model involving simultaneous solution of the transient diffusion and reaction equations of CO2 and Ca(OH)2 was developed. The model successfully includes the effects of variations in various properties such as porosity, humidity, temperature, atmospheric CO2 concentrations and chemical reaction rates. The applicability of the model was confirmed after calibration using data from accelerated carbonation experiments, and the model is used to evaluate the possible effects of climate change by inputting various future climate scenarios in Part 2., Peer-reviewed article, Published.
Carbonation in concrete infrastructure in the context of global climate change
In Part1 of this paper, a carbonation model was developed and experimentally verified which was able to forecast carbonation depth of a concrete specimen considering varying ambient temperature, humidityand CO2 concentrations. Part 2 of the paper applies the carbonation diffusion/reaction model developed in Part 1 to predict the effects of global climate change on the carbonation of concrete. Climate scenarios were formulated and combined with the model for two major Canadian cities, Toronto and Vancouver. Results show that for undamaged and unstressed concrete, climate change will significantly affect carbonation progress. The model showed that for unloaded, non-pozzolanic concrete, ultimate carbonation depths in Toronto and Vancouver could be up to 45% higher. For in-service structures under load, the rates of deterioration are likely to be even faster. This is a cause for concern, and much further effort must be devoted to fully understand these phenomena., Peer-reviewed article, Published. Received 18 October 2011; Revised 21 April 2012; Accepted 24 April 2012; Available online 10 May 2012.
Carbonation in concrete infrastructure in the context of global climate change
There is nearly unanimous consensus amongst scientists that increasing greenhouse gas emissions, including CO2 generated by human activity, are affecting the Earth’s climate. Increasing atmospheric CO2 emissions will likely increase the rates of carbonation in reinforced concrete structures.In this paper, the serviceable life, from construction through to cracking due to carbonation induced corrosion of concrete infrastructure is considered in various cities throughout the world. It was concluded that global climate change will affect the progression and will result in much higher ultimate carbonation depths in the long term., Peer-reviewed article, Published. Received 23 May 2012; Revised 1 October 2012; Accepted 9 November 2012; Available online 25 December 2012.
Cardiovascular disease and spinal cord injury
Over the last decade, there have been marked changes in the trends of morbidity and mortality among individuals with spinal cord injury (SCI). With advances in acute care and in the management of septicemia, renal failure, and pneumonia, cardiovascular complications are now a leading cause of death in those with SCI.1 Moreover, several risk factors for cardiovascular disease (CVD) are amplified in individuals with SCI compared with able-bodied individuals, including physical inactivity, dyslipidemia, blood pressure irregularities, chronic inflammation, and abnormal glycemic control.2–22. While most of the literature with respect to CVD and SCI has shown a higher prevalence of risk factors for CVD,2–22 relatively few studies have examined the prevalence of CVD itself and corresponding risk estimates.23–26 None of these studies has provided direct comparisons of risk estimates for multiple CVD outcomes in the SCI population compared to a non-SCI population, with appropriate adjustment for confounding, in a large representative sample. It thus remains unknown whether there is excess risk of both heart disease and stroke (after adjustment for potential confounders) in individuals with SCI. The current study addresses this knowledge gap by utilizing the national Canadian Community Health Survey (CCHS), which is comprised of comprehensive, up-to-date, cross-sectional data. Our aim was to estimate the prevalence of heart disease and stroke outcomes in the SCI population, to compare their risk with a non-SCI population, and to investigate this relationship after controlling for confounders., Peer-reviewed article, Published. Received December 02, 2012 ; Accepted April 22, 2013.

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