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BCIT Citations Collection

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Students use new lab to test electrical and cybersecurity systems
2016 | 2017 Project Highlights Short piece about BCIT Smart Microgrid designs., Article, Published
Study on the mechanical and environmental properties of concrete containing cathode ray tube glass aggregate
Cathode ray tube (CRT) glass is considered a hazardous material due to its lead toxicity. In addition, current disposal practices are being phased out due to their adverse environmental impacts. In this project, CRT glass was used as a fine aggregate replacement in concrete. Life-cycle material characterization was conducted by evaluating the durability and strength of the CRT-Concrete. Leaching tests were also conducted to investigate whether the material meets drinking water limits for Pb. Test results show that the plastic state of the CRT-Concrete was affected by the angularity of the glass particles. Moreover, the compressive strength of CRT-Concrete met and exceeded that of the control specimen. However, CRT-Concrete was susceptible to expansive alkali-silica reactions when more than 10% CRT replacement was used. Environmental leaching results show that lead concentrations from CRT-Concrete are below the drinking water limits depending on the CRT volume replacement and if biopolymers are used., Peer reviewed, Peer reviewed article, Received 26 July 2012 ; Accepted 24 March 2013 ; Available online 28 April 2013., Durability, CRT, Heavy metals, Glass recycling, Waste management, Sustainable concrete
A survey of stakeholder perspectives on exoskeleton technology
Background Exoskeleton technology has potential benefits for wheelchair users' health and mobility. However, there are practical barriers to their everyday use as a mobility device. To further understand potential exoskeleton use, and facilitate the development of new technologies, a study was undertaken to explore perspectives of wheelchair users and healthcare professionals on reasons for use of exoskeleton technology, and the importance of a variety of device characteristics. Methods An online survey with quantitative and qualitative components was conducted with wheelchair users and healthcare professionals working directly with individuals with mobility impairments. Respondents rated whether they would use or recommend an exoskeleton for four potential reasons. Seventeen design features were rated and compared in terms of their importance. An exploratory factor analysis was conducted to categorize the 17 design features into meaningful groupings. Content analysis was used to identify themes for the open ended questions regarding reasons for use of an exoskeleton. Results 481 survey responses were analyzed, 354 from wheelchair users and 127 from healthcare professionals. The most highly rated reason for potential use or recommendation of an exoskeleton was health benefits. Of the 17 design features, 4 had a median rating of very important: minimization of falls risk, comfort, repair and maintenance cost, and purchase cost. Factor analysis identified two main categories of design features: Functional Activities and Technology Characteristics. Qualitative findings indicated that health and physical benefits, use for activity and access reasons, and psychosocial benefits were important considerations in whether to use or recommend an exoskeleton. Conclusions This study emphasizes the importance of developing future exoskeletons that are comfortable, affordable, minimize fall risk, and enable functional activities. Findings from this study can be utilized to inform the priorities for future development of this technology., Peer-reviewed article, Published. Submission date 13 September 2014 ; Acceptance date 12 December 2014 ; Publication date 19 December 2014.
Taxonomizing features and methods for identifying at-risk students in computing courses
Proceedings from the 23rd Annual ACM Conference on Innovation and Technology in Computer Science Education. Since computing education began, we have sought to learn why students struggle in computer science and how to identify these at-risk students as early as possible. Due to the increasing availability of instrumented coding tools in introductory CS courses, the amount of direct observational data of student working patterns has increased significantly in the past decade, leading to a flurry of attempts to identify at-risk students using data mining techniques on code artifacts. The goal of this work is to produce a systematic literature review to describe the breadth of work being done on the identification of at-risk students in computing courses. In addition to the review itself, which will summarize key areas of work being completed in the field, we will present a taxonomy (based on data sources, methods, and contexts) to classify work in the area., Peer reviewed, Conference paper, Published.
Temperature and humidity distributions in mid-rise residential building suites
14th Canadian Conference on Building Science and Technology, Toronto, Canada, October 29th-30th, 2014. It is essential to design and operate buildings with good indoor air quality as people spend most of their time indoor. Their productivity, comfort and health depend on the quality of the indoor air. In addition to other air quality parameters, indoor humidity and temperature need to be controlled and maintained to acceptable ranges. These conditions may not be uniform within the house/building due to local heat and moisture sources and absence of an effective indoor air mixing mechanism as in the case of in buildings with baseboard heating systems. Localized high humidity creates favourable conditions for localized mold growth, poor indoor air quality and building envelope damage. In this paper, the indoor humidity and temperature distributions within four suites (designated as Suite ‘A’, ‘B’, ‘C’ and ‘D’) in a six-storey multi-residential building are studied. A total of 22 rooms are monitored with indoor temperature and relative humidity data loggers, and the outdoor climatic conditions are measured with a weather station for over a year. The hygrothermal performances of exterior walls in the master bedrooms of the respective suites are assessed. Analysis of the measured data suggests that the temperature variations between the rooms (bedrooms, living room, kitchen excluding bathroom) are relatively low during the summer period (mean temperature difference less than 1oC) compared to the winter period where the variations between the rooms can be as high as 2oC. The excess humidity differences between the rooms, excluding the kitchens, are in the range of 0.2 g/m 3 to 1.0 g/m 3 during both winter and summer periods, whereas the excess humidity fluctuations within the rooms are fairly the same and have standard deviation values between 0.8 g/m 3 and 1.0 g/m 3. Excess humidity is defined as the difference between the indoor and outdoor absolute humidities, quantities that are derived from the simultaneously measured temperature and relative humidity of the indoor and outdoor locations. Hygrothermal simulation results of exterior wall systems indicate that, in a mild coastal climate, the winter average indoor relative humidity shall be below 43% (for a seasonal average indoor temperature of 20oC) to avoid building envelope moisture damage., Peer reviewed article, Published.
Thermal comfort
Meeting and exceeding requirements for indoor air quality, thermal comfort, and acoustic and visual quality can lead to optimized environments that maximize well-being and performance. However, surveys on numerous buildings have revealed that satisfactory indoor environmental conditions are often not achieved. This suggests the whole industry needs more systematic methods to analyze and design indoor environments., Peer reviewed, Technical feature, Published 2018., Thermal comfort, Thermal environmental quality, ASHRAE Standard 55-2017
Thermostat setback effect in whole building performance
Proceedings of Building Physics Symposium: 29 October 2008, Leuven, Belgium. This paper describes the use of a whole building hygrothermal model (HAMFitPlus) to analyze the energy savings resulting from three programmable thermostat setting schemes in a real occupied residential house. It discusses the effect of these schemes on the indoor relative humidity and moisture performance. In the first thermostat-setting scheme, the indoor temperature is maintained constant at 21 at all time (no set-back). In the second thermostat-setting scheme, the indoor temperature is maintained at 21ºC from 7:00 to 21:00 h, and then setback to 17ºC for the remaining hours (21:00 to 7:00 h)., Conference paper, Published. A version of this document is published in: Building Physics Symposium, Lueven, Belgium, October 29-31, 2008, pp. 1-5.
Towards gender diversity in Computer Science postsecondary education
Proceedings from AERA 2018 Conference, 12 pp., New-York, NY, USA., Peer reviewed, Conference paper, Gender studies, Postsecondary education, Women's issues
Trust as a precursor to belief revision
Belief revision is concerned with incorporating new information into a pre-existing set of beliefs. When the new information comes from another agent, we must first determine if that agent should be trusted. In this paper, we define trust as a pre-processing step before revision. We emphasize that trust in an agent is often restricted to a particular domain of expertise. We demonstrate that this form of trust can be captured by associating a state partition with each agent, then relativizing all reports to this partition before revising. We position the resulting family of trust-sensitive revision operators within the class of selective revision operators of Ferme and Hansson, and we prove a representation result that characterizes the class of trust-sensitive revision operators in terms of a set of postulates. We also show that trust-sensitive revision is manipulable, in the sense that agents can sometimes have incentive to pass on misleading information., Article, Published.
Trust-sensitive belief revision
Proceedings of the Twenty-Fourth International Joint Conference on Artificial Intelligence in Buenos Aires, Argentina, 25–31 July 2015. Belief revision is concerned with incorporating new information into a pre-existing set of beliefs. When the new information comes from another agent, we must first determine if that agent should be trusted. In this paper, we define trust as a pre-processing step before revision. We emphasize that trust in an agent is often restricted to a particular domain of expertise. We demonstrate that this form of trust can be captured by associating a state partition with each agent, then relativizing all reports to this partition before revising. We position the resulting family of trust-sensitive revision operators within the class of selective revision operators of Ferme and Hansson, and we examine its properties. In particular, we show how trust-sensitive revision is manipulable, in the sense that agents can sometimes have incentive to pass on misleading information. When multiple reporting agents are involved, we use a distance function over states to represent differing degrees of trust; this ensures that the most trusted reports will be believed., Conference paper, Published.
The tyranny of chronological age
This paper presents an analysis of a phenomenon known as "The Relative Age" effect. When assessing the innate ability (or talent) of individual children who are grouped into age cohorts, systematic errors occur due to differences in biological maturity. A structural model of a multi-period progression through levels (or grades) that employs screening and selection is developed. Through a series of simulations, impact of the relative age on the of selection process is analyzed., Thesis, Draft published.
Use of hygrothermal numerical modeling to identify optimal retrofit options for high-rise buildings
Proceedings of 12th International Heat Transfer Conference: 18 August 2002, Grenoble, France. Using numerical modelling to simulate and predict the hygrothermal (i.e., combined thermal and moisture)performance of building envelopes is very recent. Key questions include: how to model accurately coupled heat-air and capillary moisture transports in building envelope components; a satisfactory definition of a set of representative environmental boundary conditions to be used for long-term hygrothermal calculations; how to characterize the moisture- and temperature-dependent properties; the effect of aging and cyclic environmental conditions on porous building materials; and how to develop sound criteria to predict the moisture durability of building envelope components. This paper presents the findings of a research project involving detailed hygrothermal modelling. The heat, air and moisture results demonstrated that the in-house model could be adapted successfully for high-rise building calculations. The findings also show how the long-term hygrothermal performance of typical wall systems can be assessed using numerical modelling. A short description of an advanced in-house heat, air and moisture model, hygIRC, is also presented., Conference paper, Published. A version of this document is published in: 12th International Heat Transfer Conference, Grenoble, France, Sept. 18, 2002, pp. 165-170.
Using EA to study the evolution of GRNs controlling biological development
This chapter surveys recent developments in simulating the evolution of GRNs in developmental biology. Over the past two decades, computational biologists have developed a number of approaches to study how developmental GRNs evolve. This has led to a number of breakthroughs in understanding the mechanisms of how species maintain their body plans, and how they evolve or speciate in response to environmental perturbations. EA uses the general evolutionary processes of repeated mutation, reproduction and selection in optimization problems. The progress in computational biology described here has deepened and refined understanding of the biological principles underlying these processes. Our aim is for this chapter to provide some inspiration to computer scientists in EA to incorporate new biologically inspired techniques. We feel this offers a large potential for improving EA efficiency. In turn, computational biology could greatly benefit from EA research, for instance in multi-objective optimization, coding of multiscale problems, and efficiencies in solution techniques. Following a brief survey of the major trends in the computational biology approaches, we discuss the refinements these have made to understanding evolutionary mechanisms. In particular, we discuss the factors affecting GRN evolvability and robustness; the effect different genetic alteration mechanisms (e.g. types of mutation) have on evolutionary speed and robustness; the role of network growth; modelling co-evolution; modelling multi-factor control of gene expression; and applying these techniques to the evolution of GRNs controlling spatially-dependent gene expression (underlying embryonic tissue differentiation). We finish with a brief summary of how these might be incorporated into and improve EA searches., Book chapter, Published.
Using ranking functions to determine plausible action histories
Proceedings of the Sixth Workshop on Nonmonotonic Reasoning, Action, and Change (NRAC-05), Edinburgh, Scotland, 2005. We use ranking functions to reason about belief change following an alternating sequence of actions and observations. At each instant, an agent assigns a plausibility value to every action and every state; the most plausible world histories are obtained by minimizing the sum of these values. Since plausibility is given a quantitative rank, an agent is able to compare the plausibility of actions and observations. This allows action occurrences to be postulated or refuted in response to new observations. We demonstrate that our formalism is a generalization of our previous work on the interaction of revision and update., Conference paper, Published.
Using thermal comfort models in health care settings
A fundamental challenge in assessing thermal comfort in health care settings is providing comfortable conditions for the diverse medical services and concurrent occupancy groups. Thermal comfort standards rely on thermal comfort models to predict thermal conditions in spaces that are satisfactory for human occupancy. However, thermal comfort standards and models have not been developed from experimental or field data in health care settings or with health-care-specific concerns in mind; therefore, their validity to assist in environmental health care design has been questioned. This study is motivated by the practical concerns with using thermal comfort models to assist in the design of HVAC systems for health care facilities. The ASHRAE thermal comfort standard (ASHRAE 2017a) requires a set of environmental and personal factors that depend onthe occupants’ activity levels and clothing insulation. Outlined in this study are the challenges in providing thermal comfort in rooms with patients and medical staff with varying activity levels and clothing insulation. Other challenges explored include looking at activity levels that are near or above the research that was used to develop the comfort models and the lack of insulation values for the clothing required to be worn by some medical personnel. This study also reviews the complexity and diversity of patients, their levels of health, and the care they are receiving relative to the assessment of thermal comfort. A final complexity discussed is applying the steady-state thermal comfort models to the transient nature of occupants in health care facilities. A literature review of thermal comfort research in health care settings is discussed and summarized. The focus has been on hospitals in general, with some studies on operating and patient rooms. A general conclusion points to patients being more tolerant of indoor conditions than predicted by the thermal comfort models and, generally, patients are more accepting of higher temperatures than the staff. The studies reviewed demonstrate that thermal comfort models can be applied with caution to rooms that serve medical staff and healthy patients—patients that are healthy in terms of thermal sensation and regulation. This paper exposes increased complexities in addressing thermal comfort in health care settings and concludes that given the critical nature of health care facilities, as well as the levels of occupant diversity and specialization, increased detail and attention to individualities are needed. The paper also reveals a lack of personal and environmental data to enable reliable thermal comfort assessments., Peer reviewed, Conference proceeding, Published., ASHRAE thermal comfort standard, Thermal comfort, HVAC systems
Utility-scale renewable energy systems
Renewable technologies such as solar or wind generation are favoured by many people concerned about the environmental and safety consequences of continued reliance on fossil-fuelled and nuclear generation. This paper focuses on two features of a societal move to renewable energy generation: their land area requirements, and the energy storage required to deliver energy services when wind and solar fluxes are inadequate. We use the IESVic Energy System Model to estimate the minimum land area and energy storage requirements for wind and solar photovoltaic generation to meet the entire 2000 US electrical demand. We model 13 locations for solar generation and 11 for wind, both singly and in various combinations, over several years of hourly climate data, and find that solar and wind generation facilities would require minimum land areas of 41,000 km2 and 193,000 km2 respectively. The smallest photovoltaic system requires storage equivalent to 76 days of average demand, while 108 days are required for wind. The generating area required by the smallest wind system is comparable to the total urbanized area of the contiguous United States, without considering land requirements for resource extraction, transmission, waste disposal, and energy storage., Article

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