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BCIT Citations Collection

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Insight into the evolution of the proton concentration during autohydrolysis and dilute-acid hydrolysis of hemicellulose
Background: During pretreatment, hemicellulose is removed from biomass via proton-catalyzed hydrolysis to produce soluble poly- and mono-saccharides. Many kinetic models have been proposed but the dependence of rate on proton concentration is not well-defined; autohydrolysis and dilute-acid hydrolysis models apply very different treatments despite having similar chemistries. In this work, evolution of proton concentration is examined during both autohydrolysis and dilute-acid hydrolysis of hemicellulose from green bamboo. An approximate mathematical model, or “toy model”, to describe proton concentration based upon conservation of mass and charge during deacetylation and ash neutralization coupled with a number of competing equilibria, was derived. The model was qualitatively compared to experiments where pH was measured as a function of time, temperature, and initial acid level. Proton evolution was also examined at room temperature to decouple the effect of ash neutralization from deacetylation. Results: The toy model predicts the existence of a steady-state proton concentration dictated by equilibrium constants, initial acetyl groups, and initial added acid. At room temperature, it was found that pH remains essentially constant both at low initial pH and autohydrolysis conditions. Acid is likely in excess of the neutralization potential of the ash, in the former case, and the kinetics of neutralization become exceedingly small in the latter case due to the low proton concentration. Finally, when the hydrolysis reaction proceeded at elevated temperatures, one case of non-monotonic behavior in which the pH initially increased, and then decreased at longer times, was found. This is likely due to the difference in rates between neutralization and deacetylation. Conclusions: The model and experimental work demonstrate that the evolution of proton concentration during hydrolysis follows complex behavior that depends upon the acetyl group and ash content of biomass, initial acid levels and temperature. In the limit of excess added acid, pH varies very weakly with time. Below this limit, complex schemes are found primarily related to the selectivity of deacetylation in comparison to neutralization. These findings indicate that a more rigorous approach to models of hemicellulose hydrolysis is needed. Improved models will lead to more efficient acid utilization and facilitate process scale-up., Peer-reviewed article, Published. Received: 23 July 2016 ; Accepted: 22 September 2016 ; Published: 21 October 2016.
Integrated analysis of whole building heat, air and moisture transfer
There is a continuous dynamic heat, air and moisture (HAM) interaction between the indoor environment, building envelope and mechanical systems. In spite of these interdependences, the current indoor, building envelope and energy analysis tools are used independently. In this paper a holistic HAM model that integrates building envelope enclosures, indoor environment, HVAC systems, and indoor heat and moisture generation mechanisms, and solves simultaneously for the respective design parameters is developed. The model is benchmarked with internationally published test cases that require simultaneous prediction of indoor environmental conditions, building envelope moisture performance and energy efficiency of a building., Peer reviewed article, Published. Received 26 February 2009, Accepted 11 March 2010, Available online 16 April 2010.
Integrated life-cycle design of building enclosures
In spite of the progress in developing methods and tools to support sustainable building design, there is still a lack of a formal approach to bridge the "no man’s land” gap between the traditional building engineering disciplines, and between these and the architecture, to achieve the level of building integration required for sustainability. This paper presents an integration framework that aims at facilitating the inclusion of life-cycle considerations in the design process from the outset, so that materials and systems are selected not only from environmentally friendly resources, but most importantly, to match service life performance expectations. The framework describes an iterative methodology to evaluate these expectations in practice, which is based on an understanding and modeling of the dynamics of the built environment to which materials, components, and systems are exposed. Quantitative methods and test protocols can be incorporated into the framework for assessing function-performance aspects of alternative solutions. Due to its complexity stemming from its inherent exposure to variable environmental loads and its multi-functionality, the framework focuses on addressing the life cycle of the building enclosure system. It is expected that the organization of the underlying principles of building life-cycle performance described in this paper will become a knowledge core that will facilitate a more integrated treatment of buildings in research, education, and practice., Peer reviewed, Peer reviewed article, Received 29 October 2010 ; Revised 13 January 2011 ; Accepted 18 January 2011 ; Available online 27 January 2011., Life-cycle, Service life, Building science, Building enclosure, Building integration
Interaction with an edu-game
We present the results of a study that explored the emotions experienced by students during interaction with an educational game for math (Heroes of Math Island). Starting from emotion frameworks in affective computing and education, we considered a larger set of emotions than in related research. For emotion labeling, we started from a standard methodology that relies on trained judges to report emotions over 20-s intervals, however, we asked judges to report all observed emotions in each interval, as opposed to only choosing one, as is standard practice. This variation allows us to discuss the appropriateness of this interval for emotion labeling. We present a detailed analysis of interrater reliability, both aggregated and over individual students, that considers not only labeling agreement among judges in terms of emotion type, but also with respect to the number of emotions detected. We also provide an analysis based on in-depth one-to-one interviews with judges, to gain insights on the challenges they encountered in labeling emotions., Peer reviewed, Peer reviewed article, First Online: 07 January 2016., Learning, Educational games, Emotion labeling, Interrater agreement, Interviewing judges, Affective states
Interaction with an edu-game: a detailed analysis of student emotions and judges' perceptions
We present the results of a study that explored the emotions experienced by students during interaction with an educational game for math (Heroes of Math Island). Starting from emotion frameworks in affective computing and education, we considered a larger set of emotions than in related research. For emotion labeling, we started from a standard methodology that relies on trained judges to report emotions over 20-s intervals, however, we asked judges to report all observed emotions in each interval, as opposed to only choosing one, as is standard practice. This variation allows us to discuss the appropriateness of this interval for emotion labeling. We present a detailed analysis of interrater reliability, both aggregated and over individual students, that considers not only labeling agreement among judges in terms of emotion type, but also with respect to the number of emotions detected. We also provide an analysis based on in-depth one-to-one interviews with judges, to gain insights on the challenges they encountered in labeling emotions., Not peer reviewed, Article
Introductory mathematics for computer science
4th custom edition., Not peer reviewed, Book, Published.
Introductory mathematics for computer science
3rd custom edition for BCIT., Published., Peer reviewed, Book
Introductory mathematics for computer science
Taken from: Basic technical mathematics : with calculus, metric version, seventh edition by Allyn J. Washington, Logic and computer design fundamentals, second edition, updated by M. Morris Mano and Charles R. Kime. Custom edition for British Columbia Institute of Technology., Book, Published., Peer reviewed
Investigation of the moisture buffering potential of magnesium oxide board
Research report submitted to Peter Francis, President, MAGO Building Products Ltd in April 2016. Passive humidity control in buildings can be achieved by incorporating materials with moisture buffering potential in that these materials absorb moisture at peak times and give off the stored up moisture at low moisture production times thereby stabilizing the interior relative humidity. Some of the advantages of this phenomenon include but are not limited to energy savings, improvement of thermal comfort and perceived air quality. As such, it is necessary to investigate different materials for their moisture buffering capabilities. As part of product development, the moisture buffering characteristics of Magnesium oxide board (Magnesia board) is experimentally investigated. Other considerations such as the impact of surface finishing and ventilation are also assessed. The experiment is done by monitoring twin buildings termed the Whole Building Performance Research Laboratory (WBPRL) while measuring the relative humidity evolution in time. One is set as the reference building and finished with gypsum wallboard owing to its wide industry use. The other is set as the reference building and covered with the Magnesia board. Both buildings are first validated under non-hygroscopic conditions to ensure similar hygrothermal loading and operation of both buildings. Next, four tests are conducted to simulate surface treatments, ventilation effects, and occupancy density. For each test run, four cases are created for different surface treatment configurations. From the test, it is found that magnesia board and gypsum demonstrate similar moisture buffering characteristics. In the as-in service case where the gypsum wallboard is painted with latex paint, as it is the current common practice, and magnesia board with the company specified paint, the later demonstrates slightly better moisture buffering due to the high permeability surface treatment., Research report, Published.
Iterated belief change
Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI-05) in Edinburgh, Scotland, 2005. We use a transition system approach to reason about the evolution of an agent’s beliefs as actions are executed. Some actions cause an agent to perform belief revision and some actions cause an agent to perform belief update, but the interaction between revision and update can be nonelementary. We present a set of basic postulates describing the interaction of revision and update, and we introduce a new belief evolution operator that gives a plausible interpretation to alternating sequences of revisions and updates., Conference paper, Published.
Iterated belief change due to actions and observations
In action domains where agents may have erroneous beliefs, reasoning about the effects of actions involves reasoning about belief change. In this paper, we use a transition system approach to reason about the evolution of an agent's beliefs as actions are executed. Some actions cause an agent to perform belief revision while others cause an agent to perform belief update, but the interaction between revision and update can be non-elementary. We present a set of rationality properties describing the interaction between revision and update, and we introduce a new class of belief change operators for reasoning about alternating sequences of revisions and updates. Our belief change operators can be characterized in terms of a natural shifting operation on total pre-orderings over interpretations. We compare our approach with related work on iterated belief change due to action, and we conclude with some directions for future research., Peer-reviewed article, Published.
Lessons learnt from the shotcrete repair of the Powell River concrete hulks, and their applicability to other marine structures
Background : Concrete structures can be damaged by many chemical or physical processes. Where such damages affect appearance, serviceability or structural integrity, repair may be required. 10 decommissioned concrete ships form a massive floating breakwater on the Malaspina Strait in the City of Powell River in British Columbia, Canada. The ships are subjected to extremely onerous conditions, namely in the salt water splash zone under seasonal freeze-thaw cycling. This paper provides anecdotal evidence based on condition assessments after repairs were car-ried out, on how a well-matched repair concrete can significantly extend the service life of these and similar sorts of marine structures. Methods: Condition assessment was carried out using sounding, visual examination, photo and video documentation, compressive strength testing, splitting tensile strength testing, chloride ion concentration testing, and half-cell potential testing. Results: It was found that the areas which had been repaired had fared very well, with no observable de-terioration. The non-repaired areas of the structures had continued to deteriorate, particularly in non-submerged areas, close to the waterline, along with new impact damage. Conclusion: Durable concrete repairs can be achieved even for concrete exposed to extreme environ-mental conditions. Key conditions for such repairs are: complete removal of the deteriorated portions of the original concrete, removal of all loose corrosion products from exposed reinforcing steel, prepara-tion of a clean, firm, rough, surface dry but partially or fully water saturated, substrate surface, selection of a compatible repair material, use of an application technique which facilitates high bond strength between substrate and repair material, adequate curing, and protection of the repair material while immature., Peer-reviewed article, Published. Received: September 12, 2015; Revised: December 19, 2015; Accepted: June 28, 2016.

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