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BCIT Citations Collection

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Modelling the effects of structural cracking on carbonation front advance into concrete
Concrete structures are almost certain to contain cracks due to different physiochemical mechanisms. The formation of cracks is sure to affect its durability by altering ion and fluid transport properties. This includes the incursion of CO2 into the structure. There presently exists no consensus on how to model the effects of structural cracking on carbonation progress within concrete structures. This paper first examines the concept of effective diffusion based on simultaneous diffusion of CO2 through sound and cracked concrete and then considers a series diffusion concept where CO2 diffuses first into the crack, and then outwards into the sound concrete. It is concluded that the effective diffusion concept is not valid for structurally cracked concrete. Instead, research efforts should be concentrated on developing a two–phase series diffusion model., Peer-reviewed article, Published.
Moisture response of sheathing board in conventional and rain-screen wall systems with shiplap cladding
Building enclosures are subjected to a random climatic loading on the exterior surface and a relatively stable indoor condition on the interior. These loadings result in a transport of heat, air, and moisture across the building enclosure. In this paper, the drying and wetting of sheathing board in two exterior walls, more specifically 2×6 in.2 wood-frame conventional (no strapping between sheathing membrane and cladding) and a rain-screen wall system (with vertical strapping), are investigated through an experimental field study. The experiment is carried out at British Columbia Institute of Technology field exposure test facility, where the test walls are exposed to the coastal climate (Vancouver weather) on the exterior and controlled indoor temperature and relative humidity conditions in the interior. The field experimental results indicate significant moisture accumulation on the exterior sheathing boards (plywood) during the Winter period. During the 9-month monitoring period from March 13 to Dec. 6, 2009, the plywood underwent a process of drying and wetting. In both the conventional and rain-screen wall systems, the plywood dried to a comparable moisture level during the Summer before the wetting process started. For the wall systems considered in this study, the plywood in the rain-screen wall has a tendency of faster drying and wetting in the Spring and Fall seasons, respectively, in comparison to the plywood in the conventional wall, which is attributed to the presence of an air gap in the rain-screen wall between the sheathing membrane and the cladding. A similar trend is observed during the monitoring period from December 7 to June 15, 2010., Peer-reviewed article, Published. Manuscript received January 14, 2010; accepted for publication August 14, 2010; published online October 2010.
Molecular targets for therapeutic intervention after spinal cord injury
In an effort to develop therapies for promoting neurological recovery after spinal cord injury, much work has been done to identify the cellular and molecular factors that control axonal regeneration within the injured central nervous system. This review summarizes the current understanding of a number of the elements within the spinal cord environment that inhibit axonal growth and outlines the factors that influence the neuron’s ability to regenerate its axon after injury. Recent insights in these areas have identified important molecular pathways that are potential targets for therapeutic intervention, raising hope for victims of spinal cord injury., Peer-reviewed article, Published.
Multi-agent control system for real-time adaptive VVO/CVR in Smart Substation
Proceedings of IEEE Electrical Power And Energy Conference, London, Ontario, Oct. 2012. This paper proposes a multi-agent based control system for real-time and adaptive Volt/VAR Optimization (VVO) and Conservation Voltage Reduction (CVR) in Smart Substations. The design and implementation of the proposed distributed control system using agent technology is discussed in the paper. Furthermore, the architecture, tasks and limits of each Intelligent Agent (IA) as a component of a multi-agent system (MAS) have been explained. A number of control functions are simulated and the results are presented in the paper. The results obtained demonstrate the potential of MAS for improving the efficiency of the system., Conference paper, Published.
The need for an accurate indoor humidity model for building envelope performance analysis
Proceedings of the Fourth International Building Physics Conference: Energy Efficiency and New Approaches: 15 June 2009, Istanbul, Turkey. The performance of a building envelope component is usually assessed based on the moisture analysis of individual components (such as cladding, sheathing board and/or drywall) for their drying potentials and likelihood of occurrence of problems associated with high moisture accumulation. In the current building envelope simulation practice, the indoor and outdoor boundary conditions are predefined in the context of the local weather data. The indoor boundary conditions are usually assumed to be constant throughout the simulation period, or two sets of values for the summer and winter periods are assumed. Although the outdoor boundary condition (weather data) is independent of the hygrothermal condition of the envelope, the indoor condition is highly influenced by the building enclosure and occupants? activities. Consequently, simplistic assumptions of indoor humidity profiles, which ignore the dynamic coupling of the indoor environment and building enclosure and represented with a set of empirical values, may lead to inaccurate conclusion about the moisture performance of the building enclosure. In this paper, the effects of indoor humidity profiles that are assumed during moisture performance evaluation of exterior building envelope component are analyzed. The indoor humidity profiles, which are considered in the study, are based on measured and simulated data of a real house. Indoor humidity models including a whole building hygrothermal model are used to generate four indoor humidity profiles. The hygrothermal dynamic responses of the building envelope component with respect to the various cases of indoor humidity assumptions are simulated and analyzed. The simulation results suggest that it is important to have more accurate indoor boundary conditions data, which are based on measurement or whole building hygrothermal modelling, to satisfactorily asses the moisture performance of a building enclosure and potential occupants health problems related to mould growth., Peer reviewed article, Published.
New approaches to designing genes by evolution in the computer
The field of Evolutionary Computation (EC) has been inspired by ideas from the classical theory of biological evolution, with, in particular, the components of a population from which reproductive parents are chosen, a reproductive protocol, a method for altering the genetic information of offspring, and a means for testing the fitness of offspring in order to include them in the population. In turn, impressive progress in EC - understanding the reasons for efficiencies in evolutionary searches - has begun to influence scientific work in the field of molecular evolution and in the modeling of biological evolution (Stemmer, 1994a,b; van Nimwegen et al. 1997; 1999; Crutchfield & van Nimwegen, 2001). In this chapter, we will discuss how developments in EC, particularly in the area of crossover operators for Genetic Algorithms (GA), provide new understanding of evolutionary search efficiencies, and the impacts this can have for biological molecular evolution, including directed evolution in the test tube. GA approaches have five particular elements: encoding (the ‘chromosome’); a population; a method for selecting parents and making a child chromosome from the parents' chromosomes; a method for altering the child’s chromosomes (mutation and crossover/recombination); criteria for fitness; and rules, based on fitness, by which offspring are included into the population (and parents retained). We will discuss our work and others’ on each of these aspects, but our focus is on the substantial efficiencies that can be found in the alteration of the child chromosome step. For this, we take inspiration from real biological reproduction mechanisms., Book chapter, Published.
Noise in the segmentation gene network of Drosophila, with implications for mechanisms of body axis specification
Specification of the anteroposterior (head-to-tail) axis in the fruit fly Drosophila melanogaster is one of the best understood examples of embryonic pattern formation, at the genetic level. A network of some 14 segmentation genes controls protein expression in narrow domains which are the first manifestation of the segments of the insect body. Work in the New York lab has led to a databank of more than 3300 confocal microscope images, quantifying protein expression for the segmentation genes, over a series of times during which protein pattern is developing (http://flyex.ams.sunysb.edu/FlyEx/). Quantification of the variability in expression evident in this data (both between embryos and within single embryos) allows us to determine error propagation in segmentation signalling. The maternal signal to the egg is highly variable, with noise levels more than several times those seen for expression of downstream genes. This implies that error suppression is active in the embryonic patterning mechanism. Error suppression is not possible with the favoured mechanism of local concentration gradient reading for positional specification. We discuss possible patterning mechanisms which do reliably filter input noise., Peer-reviewed article, Published.
A novel Volt-VAR Optimization engine for smart distribution networks utilizing Vehicle to Grid dispatch
In recent years, Smart Grid technologies such as Advanced Metering, Pervasive Control, Automation and Distribution Management have created numerous control and optimization opportunities and challenges for smart distribution networks. Availability of Co-Gen loads and/or Electric Vehicles (EVs) enable these technologies to inject reactive power into the grid by changing their inverter’s operating mode without considerable impact on their active power operation. This feature has created considerable opportunity for distribution network planners to explore if EVs could be used in the distribution network as reliable VAR suppliers. It may be possible for network operators to employ some EVs as VAR suppliers for future distribution grids. This paper proposes an innovative Smart Grid-based Volt-VAR Optimization (VVO) engine, capable of minimizing system power loss cost as well as the operating cost of switched Capacitor Banks, while optimizing the system voltage using an improved Genetic Algorithm (GA) with two levels of mutation and two levels of crossover. The paper studies the impact of EVs with different charging and penetration levels on VVO in different operating scenarios. Furthermore, the paper demonstrates how a typical VVO engine could benefit from V2G’s reactive power support. In order to assess V2G impacts on VVO and test the applicability of the proposed VVO, revised IEEE-123 Node Test Feeder in presence of various load types is used as case study., Article, Published. Received 24 May 2014, Revised 23 July 2015, Accepted 29 July 2015, Available online 8 August 2015.
NRC-IRC develops evaluation protocol for innovative vapour barrier
Vapour barriers were originally intended to keep building assemblies from getting wet, but they can sometimes end up preventing assemblies from drying out. An innovative new product to manage moisture accumulation in the building envelope, however, may be able to address both issues: while the product acts as a vapour barrier under most conditions, it also allows excess moisture to escape. The Canadian Construction Materials Centre (CCMC) set out to determine whether this product can serve as a vapour barrier and an air barrier system and whether it conformed to the intent of applicable building code requirements. In collaboration with NRC-IRC researchers, CCMC developed a testing protocol for its evaluation, which was based on laboratory testing requirements for vapour diffusion, air leakage control and durability., Article, Published.
On keeping secrets
Proceedings of the 2015 Workshops at the Twenty-Ninth AAAI Conference on Artificial Intelligence in Austin, USA, 2015. Communication involves transferring information from one agent to another. An intelligent agent, either human or machine, is often able to choose to hide information in order to protect their interests. The notion of information hiding is closely linked to secrecy and dishonesty, but it also plays an important role in domains such as software engineering. In this paper, we consider the ethics of information hiding, particularly with respect to intelligent agents. In other words, we are concerned with situations that involve a human and an intelligent agent with access to different information. Is the intelligent agent justified in preventing a human user from accessing the information that they possess? This is trivially true in the case where access control systems exist. However, we are concerned with the situation where an intelligent agent is able to using a reasoning system to decide not to share information with all humans. On the other hand, we are also concerned with situations where humans hide information from machines. Are we ever under a moral obligation to share information with a computional agent? We argue that questions of this form are increasingly important now, as people are increasingly willing to divulge private information to machines with a great capacity to reason with that information and share it with others., Conference paper, Published.
On the representation and verification of cryptographic protocols in a theory of action
Proceedings of 2010 Eighth Annual International Conference on Privacy Security and Trust (PST) in Ottawa, ON, Canada, 17-19 Aug. 2010. Cryptographic protocols are usually specified in an informal, ad hoc language, with crucial elements, such as the protocol goal, left implicit. We suggest that this is one reason that such protocols are difficult to analyse, and are subject to subtle and nonintuitive attacks. We present an approach for formalising and analysing cryptographic protocols in a theory of action, specifically the situation calculus. Our thesis is that all aspects of a protocol must be explicitly specified. We provide a declarative specification of underlying assumptions and capabilities in the situation calculus. A protocol is translated into a sequence of actions to be executed by the principals, and a successful attack is an executable plan by an intruder that compromises the specified goal. Our prototype verification software takes a protocol specification, translates it into a high-level situation calculus (Golog) program, and outputs any attacks that can be found. We describe the structure and operation of our prototype software, and discuss performance issues., Conference paper, Published.
Optimal scaling of weight and waist circumference to height for adiposity and cardiovascular disease risk in individuals with spinal cord injury
Study Design: Observational cross-sectional study. Objectives: Body mass index (BMI), measured as a ratio of weight (Wt) to the square of height (Wt/Ht(2)), waist circumference (WC) and waist-to-height ratio (WHtR) are common surrogate measures of adiposity. It is not known whether alternate scaling powers for height might improve the relationships between these measures and indices of obesity or cardiovascular disease (CVD) risk in individuals with spinal cord injury (SCI). We aimed to estimate the values of 'x' that render Wt/Ht(x) and WC/Ht(x) maximally correlated with dual energy x-ray absorptiometry (DEXA) total and abdominal body fat and Framingham Cardiovascular Risk Scores. Setting: Canadian public research institution. Methods: We studied 27 subjects with traumatic SCI. Height, Wt and body fat measurements were determined from DEXA whole-body scans. WC measurements were also obtained, and individual Framingham Risk Scores were calculated. For values of 'x' ranging from 0.0 to 4.0, in increments of 0.1, correlations between Wt/Ht(x) and WC/Ht(x) with total and abdominal body fat (kg and percentages) and Framingham Risk Scores were computed. Results: We found that BMI was a poor predictor of CVD risk, regardless of the scaling factor. Moreover, BMI was strongly correlated with measures of obesity, and modification of the scaling factor from the standard (Wt/Ht(2)) is not recommended. WC was strongly correlated with both CVD risk and obesity, and standard measures (WC and WHtR) are of equal predictive power. Conclusion: On the basis of our findings from this sample, alterations in scaling powers may not be necessary in individuals with SCI; however, these findings should be validated in a larger cohort., Peer-reviewed article, Published. Received 25 February 2014; revised 1 May 2014; accepted 1 August 2014; published online 30 September 2014.
Optimization and single-laboratory validation of a method for the determination of flavonolignans in milk thistle seeds by high-performance liquid chromatography with ultraviolet detection
Seeds of milk thistle, Silybum marianum (L.) Gaertn., are used for treatment and prevention of liver disorders and were identified as a high priority ingredient requiring a validated analytical method. An AOAC International expert panel reviewed existing methods and made recommendations concerning method optimization prior to validation. A series of extraction and separation studies were undertaken on the selected method for determining flavonolignans from milk thistle seeds and finished products to address the review panel recommendations. Once optimized, a single-laboratory validation study was conducted. The method was assessed for repeatability, accuracy, selectivity, LOD, LOQ, analyte stability, and linearity. Flavonolignan content ranged from 1.40 to 52.86 % in raw materials and dry finished products and ranged from 36.16 to 1570.7 μg/mL in liquid tinctures. Repeatability for the individual flavonolignans in raw materials and finished products ranged from 1.03 to 9.88 % RSD, with HorRat values between 0.21 and 1.55. Calibration curves for all flavonolignan concentrations had correlation coefficients of >99.8 %. The LODs for the flavonolignans ranged from 0.20 to 0.48 μg/mL at 288 nm. Based on the results of this single-laboratory validation, this method is suitable for the quantitation of the six major flavonolignans in milk thistle raw materials and finished products, as well as multicomponent products containing dandelion, schizandra berry, and artichoke extracts. It is recommended that this method be adopted as First Action Official Method status by AOAC International., Peer-reviewed article, Published. Received 1 June 2015; Revised 14 July 2015; Accepted 16 July 2015; Published online 31 July 2015.
Ordinal conditional functions for nearly counterfactual revision
Proceedings of the 16th International Workshop on Non-Monotonic Reasoning (NMR 2016), Cape Town, South Africa; April 22-24, 2016. We are interested in belief revision involving conditional statements where the antecedent is almost certainly false. To represent such problems, we use Ordinal Conditional Functions that may take infinite values. We model belief change in this context through simple arithmetical operations that allow us to capture the intuition that certain antecedents can not be validated by any number of observations. We frame our approach as a form of finite belief improvement, and we propose a model of conditional belief revision in which only the "right" hypothetical levels of implausibility are revised., Conference paper, Published.
Osmoregulation in the halophilic bacterium halomonas elongata
Halophilic bacteria use a variety of osmoregulatory methods, such as the accumulation of one or more compatible solutes. The wide diversity of compounds that can act as compatible solute complicates the task of understanding the different strategies that halophilic bacteria use to cope with salt. This is specially challenging when attempting to go beyond the pathway that produces a certain compatible solute towards an understanding of how the metabolic network as a whole addresses the problem. Metabolic reconstruction based on genomic data together with Flux Balance Analysis (FBA) is a promising tool to gain insight into this problem. However, as more of these reconstructions become available, it becomes clear that processes predicted by genome annotation may not reflect the processes that are active in vivo. As a case in point, E. coli is unable to grow aerobically on citrate in spite of having all the necessary genes to do it. It has also been shown that the realization of this genetic potential into an actual capability to metabolize citrate is an extremely unlikely event under normal evolutionary conditions. Moreover, many marine bacteria seem to have the same pathways to metabolize glucose but each species uses a different one. In this work, a metabolic network inferred from genomic annotation of the halophilic bacterium Halomonas elongata and proteomic profiling experiments are used as a starting point to motivate targeted experiments in order to find out some of the defining features of the osmoregulatory strategies of this bacterium. This new information is then used to refine the network in order to describe the actual capabilities of H. elongata, rather than its genetic potential., Peer-reviewed article, Published. Received: September 20, 2016; Accepted: November 17, 2016; Published: January 12, 2017.
The path of the smart grid
Exciting yet challenging times lie ahead. The electrical power industry is undergoing rapid change. The rising cost of energy, the mass electrification of everyday life, and climate change are the major drivers that will determine the speed at which such transformations will occur. Regardless of how quickly various utilities embrace smart grid concepts, technologies, and systems, they all agree onthe inevitability of this massive transformation. It is a move that will not only affect their business processes but also their organization and technologies., Final article published

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