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BCIT Citations Collection

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An urban metabolism and ecological footprint assessment of Metro Vancouver
As the world urbanizes, the role of cities in determining sustainability outcomes grows in importance. Cities are the dominant form of human habitat, and most of the world's resources are either directly or indirectly consumed in cities. Sustainable city analysis and management requires understanding the demands a city places on a wider geographical area and its ecological resource base. We present a detailed, integrated urban metabolism of residential consumption and ecological footprint analysis of the Vancouver metropolitan region for the year 2006. Our overall goal is to demonstrate the application of a bottom-up ecological footprint analysis using an urban metabolism framework at a metropolitan, regional scale. Our specific objectives are: a) to quantify energy and material consumption using locally generated data and b) to relate these data to global ecological carrying capacity. Although water is the largest material flow through Metro Vancouver (424,860,000 m3), it has the smallest ecological footprint (23,100 gha). Food (2,636,850 tonnes) contributes the largest component to the ecological footprint (4,514,400 gha) which includes crop and grazing land as well as carbon sinks required to sequester emissions from food production and distribution. Transportation fuels (3,339,000 m3) associated with motor vehicle operation and passenger air travel comprises the second largest material flow through the region and the largest source of carbon dioxide emissions (7,577,000 tonnes). Transportation also accounts for the second largest component of the EF (2,323,200 gha). Buildings account for the largest electricity flow (17,515,150 MWh) and constitute the third largest component of the EF (1,779,240 gha). Consumables (2,400,000 tonnes) comprise the fourth largest component of the EF (1,414,440 gha). Metro Vancouver's total Ecological Footprint in 2006 was 10,071,670 gha, an area approximately 36 times larger than the region itself. The EFA reveals that cropland and carbon sinks (forested land required to sequester carbon dioxide emissions) account for 90% of Metro Vancouver's overall demand for biocapacity. The per capita ecological footprint is 4.76 gha, nearly three times the per capita global supply of biocapacity. Note that this value excludes national government services that operate outside the region and could account for up to an additional 2 gha/ca., Peer-reviewed article, Published. Received 23 December 2011; Revised 25 February 2013; Accepted 5 March 2013; Available online 19 April 2013.
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 evolutionary computations to understand the design and evolution of gene and cell regulatory networks
This paper surveys modeling approaches for studying the evolution of gene regulatory networks (GRNs). Modeling of the design or ‘wiring’ of GRNs has become increasingly common in developmental and medical biology, as a means of quantifying gene–gene interactions, the response to perturbations, and the overall dynamic motifs of networks. Drawing from developments in GRN ‘design’ modeling, a number of groups are now using simulations to study how GRNs evolve, both for comparative genomics and to uncover general principles of evolutionary processes. Such work can generally be termed evolution in silico. Complementary to these biologically-focused approaches, a now well-established field of computer science is Evolutionary Computations (ECs), in which highly efficient optimization techniques are inspired from evolutionary principles. In surveying biological simulation approaches, we discuss the considerations that must be taken with respect to: (a) the precision and completeness of the data (e.g. are the simulations for very close matches to anatomical data, or are they for more general exploration of evolutionary principles); (b) the level of detail to model (we proceed from ‘coarse-grained’ evolution of simple gene-gene interactions to ‘fine-grained’ evolution at the DNA sequence level); (c) to what degree is it important to include the genome’s cellular context; and (d) the efficiency of computation. With respect to the latter, we argue that developments in computer science EC offer the means to perform more complete simulation searches, and will lead to more comprehensive biological predictions., Peer-reviewed article, 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
Variable patterning in fruit fly embryos due to basins of attraction in underlying gene regulatory dynamics
Proceedings of Previous work on a reaction-diffusion model of a 4-gene regulatory network governing insect segmentation characterized the dynamical basis of robustness to perturbations in this system [1,2]. Here, we computationally study system behavior near bifurcation points corresponding to weak-allele mutant embryos (i.e. with altered gene regulation). Our computations suggest that the variable expressivity and incomplete penetrance observed in some gene mutations may stem from response of the dynamical system to variable input (regulatory genes) near such bifurcation points., Peer-reviewed article, Published. Received: 14 April 2012; Accepted: 2 October 2012.
Variation of select flavonols and chlorogenic acid content of elderberry collected throughout the Eastern United States
American elderberries are commonly collected from wild plants for use as food and medicinal products. The degree of phytochemical variation among wild populations has not been established and might affect the overall quality of elderberry dietary supplements. The three major flavonols identified in elderberries are rutin, quercetin and isoquercetin. Variation in the flavonols and chlorogenic acid was determined for 107 collections of elderberries from throughout the eastern United States using an optimized high performance liquid chromatography with ultraviolet detection method. The mean content was 71.9 mg per 100 g fresh weight with variation ranging from 7.0 to 209.7 mg per 100 g fresh weight within the collected population. Elderberries collected from southeastern regions had significantly higher contents in comparison with those in more northern regions. The variability of the individual flavonol and chlorogenic acid profiles of the berries was complex and likely influenced by multiple factors. Several outliers were identified based on unique phytochemical profiles in comparison with average populations. This is the first study to determine the inherent variability of American elderberries from wild collections and can be used to identify potential new cultivars that may produce fruits of unique or high-quality phytochemical content for the food and dietary supplement industries., Peer-reviewed article, Published. Received 16 April 2015; Revised 29 October 2015; Accepted 20 December 2015; Available online 23 December 2015.
Variations in the hygrothermal properties of several wood-based building products
Proceedings of Second International Building Physics Conference: 14 September 2003, Leuven, Belgium. A systematic investigation of the hygrothermal properties of a number of oriented strand boards, plywood products, wood fibreboards and composite wood sidings has resulted in new information on the variations of thermal conductivity, water vapour permeability, moisture diffusivity, sorption- desorption-suction isotherms, water absorption coefficient and air permeability of these classes of products in North America. The experimental and analytical procedures used in the investigation are all based eitheron International Standards or on well-documented and peer-reviewed approaches. This paper presents the description of the products in each category and detailed information on the range of properties. The details include, density and temperature dependences of thermal conductivity,dependence of vapour resistance factor on relative humidity, dependence of moisture diffusivity on moisture concentration, equilibrium moisture content for the full range of relative humidity, variations in the water absorption coefficients and dependence of air permeability on pressure difference., Conference paper, Published. A version of this document is published in: Research in Building Physics, Leuven, Belgium, Sept. 14-18, 2003, pp. 35-42.
Verification and validation
The hygrothermal performance of building envelope systems is dictated by their responses to combined heat, air and moisture fluctuations produced by exterior and interior conditions. Research has focused on both laboratory experimentation and modeling of envelope systems by computer programs (hygrothermal tools). Experimental studies played a crucial role in the development of hygrothermal tools, and continue to offer useful information for their improvement. To be used with confidence, however, hygrothermal tools must be verified and, if possible, validated. To date, no comprehensive schemes for benchmarking hygrothermal tools exist as, for example, exist for energy simulation tools. Three comparisons are typically used to show the practical merits of simulation tools: inter-model, analytical, and empirical. This paper demonstrates how confidence in a 1-dimensional hygrothermal simulation tool can be built by such comparisons, and proposes them as the basis for a verification and validation methodology., Research report, Published.
Which foot? A comparative effectiveness study of subject-generated ankle kinetics as a measure of prosthetic foot function across a range of K levels
This double-blind randomized controlled trial offers evidence that flexible energy storage return (ESR) feet produce lower peak moments during walking and are preferred by trans-tibial amputees., Research report, Published.

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