York University
  • Toronto, Ontario, Canada
Recent publications
This paper studies fully distributed formation control problems for multi-quadrotor systems with external disturbances via an event-triggered approach. For leader-follower multi-quadrotor systems, a fully distributed event-triggered formation control (DETFC) framework is proposed by utilizing an adaptive sliding-mode control approach, which does not rely on any global information of the network topology. The finite-time reachability of the sliding-mode surface can be guaranteed for the states of the nonlinear, coupled and underactuated system subject to external disturbances. Meanwhile, the zeno behavior of the proposed event-triggered protocol is proved to be excluded. A novel dynamic sliding-mode surface is designed to guarantee the formation performance as the quadrotor state trajectories move on the constructed sliding manifold. Via Lyapunov stability theory, sufficient conditions to ensure the formation results are derived for multi-quadrotor systems. Simulations and experiments are conducted to validate the effectiveness of the proposed control scheme.
Temperature distribution in the power transformers is investigated in this study under Geomagnetically Induced Current (GIC) conditions. Thermal stress can significantly reduce the insulation life, and in the case of excessive hot spot temperature (HST), catastrophic failure of transformers is likely,as happened in the pastGeomagnetic Disturbance (GMD) events. Although a few reports emphasize the impact of GIC on the local heating within the transformers, especially in the structural parts, the effect of GIC on the thermal condition of transformers has not been investigated profoundly.This paper studies thepower transformer HST duringthe GIC. Since finding stray losses under GIC conditions is challenging, a hybrid approach, including a topological transformer model and 3D finite element method (FEM), is implemented. The detailed topological transformer model is utilized in the EMTP time-domain simulations to determine the harmonic currents at different GIC levels. Additionally, FEM is employed to calculate the temperature distribution within the transformer. The simulation results reveal that the structural parts are saturated with low GIC magnitudes, resulting in high stray losses and local hot spot heating in those areas. Furthermore, the tank can reach high temperatures at mid-GIC levels. These results clearly show that the transformer structural parts are highly vulnerable under severe GIC situations.
Apart from chemical pollutants and organic matter, wastewater treatment plants release microorganisms into the environment. This microbial community, released into the environment, may pose a biological risk due to present pathogens or multi-resistant bacteria. The latter is especially dangerous; antibiotic-resistant microorganisms may potentially transfer resistant genes to non-resistant microorganisms. Moreover, the various influent composition (e.g. micropollutants, total dissolved solids, chemical oxygen demand, nitrogen and phosphorous level), operating parameters of water treatment (e.g. pH, dissolved oxygen, temperature, hydraulic and sludge retention time) lead to a microbial shift. It may influence the wastewater treatment performance, especially biological treatment. Hence, it is essential to understand the relationship between microbial community and the water treatment process. It would help to recognize the crucial microorganisms to wastewater treatment performance as well as facilitate its optimization. Hence, this chapter aims to characterize the microbial community shift in wastewater treatment plants. The driving factors that affect the shift will also be revised. Moreover, the dynamics of microbial community shift will be discussed.
Bamboo gasification is a promising social innovation for sustainable energy and rural development in Uganda. Bamboo is a fast-growing and versatile plant that can provide a renewable and reliable source of biomass for gasification. Bamboo gasification can generate electricity and heat, as well as other valuable products, such as biochar, bio-oil, or bio-fertilizer. Bamboo gasification can also contribute to various Sustainable Development Goals, such as poverty reduction, climate change mitigation, forest conservation, and job creation. However, bamboo gasification faces many challenges and barriers in Uganda, such as a lack of awareness, research, investment, and support. This chapter aims to explore the potential and challenges of bamboo gasification in Uganda and to propose a conceptual and methodological framework for its promotion and commercialization. The chapter reviews the literature and case studies on biomass gasification, bamboo cultivation, and utilization, technical and environmental performance of gasification technologies, applications and markets for syngas and its derivatives, socio-economic and policy aspects of bamboo gasification, and sensitivity analysis of feasibility assessment. Based on the review, the chapter presents a conceptual model that depicts the main components and relationships of the bamboo gasification system and its environment. The chapter also proposes a 5-step approach that guides the decision makers to apply the conceptual model to any region or country that has bamboo resources. The chapter concludes with some limitations of the conceptual model and some directions for future research.
Cameroon's Vision 2035 aims to become an emergent economy, and energy is a crucial resource for achieving this goal. However, only 20% of the rural population has access to electricity, which limits their economic opportunities. This study investigates the reasons for the slow progress of rural electrification in Cameroon since the establishment of the Rural Electrification Agency in 1998. The study also aims to identify the challenges and propose a model for rural electrification. The study uses the stakeholder theory as a framework and adopts a survey research design with a qualitative approach. Data is collected from primary and secondary sources, using semi-structured interviews and personnel as data collection instruments. The study samples 10 key institutions and selects 7 respondents for data analysis, which is done through in-depth content analysis. The study finds that corruption and poor coordination of the rural electrification sector are the main barriers to rural electrification in Cameroon. The study recommends a bottom-up policy-making process for rural electrification and suggests a model for implementation.
This chapter explores how renewable energy can support sustainable development in South Africa. It reviews the literature on four topics: the current and future trends of renewable energy use and production; the factors that influence renewable energy adoption and diffusion; the effects of renewable energy on different aspects of sustainability; and the policy and technical measures to enhance the role of renewable energy in achieving sustainability goals. The chapter shows that South Africa has made considerable progress in using and producing renewable energy, but still faces some obstacles and challenges that need to be addressed. The chapter proposes some potential policy and technical solutions to create a favorable environment for renewable energy transition in South Africa. The chapter also acknowledges some research gaps and limitations and suggests some areas for further research. The chapter aims to enrich the knowledge of renewable energy and sustainability and provide useful insights and lessons for policymakers, investors, developers, and users of renewable energy technologies in South Africa and other countries.
This chapter examines the dynamics of renewable energy (RE) in the North African electricity market, focusing on the Algerian case. The North African countries of Africa, namely Morocco, Algeria, and Tunisia, have a high potential for solar and wind power generation, which could meet their electricity demand and reduce their greenhouse gas emissions. However, they also face various challenges and barriers for RE investment and development, such as policy, technology, economics, behavior, and sustainability. The chapter aims to answer the following questions: What are the policies that support or hinder the development of RE in North Africa? How do they affect the supply and demand of electricity from RE sources? How do they influence regional integration and cooperation in the electricity sector? To answer these questions, the chapter conducts a literature review of articles and journals on this topic and then designs a conceptual model to analyze the dynamics of RE in the Algerian electricity market using system thinking and causal loop diagrams.
Renewable energy (RE) is a key solution to address the energy challenges and aspirations of the African people, who still suffer from low access to electricity and high dependence on traditional biomass. However, RE in Africa faces many technical, economic, social, environmental, institutional, and policy barriers that need to be overcome. This book provides a comprehensive and multidisciplinary perspective on RE in Africa, covering various aspects such as drivers, impacts, and solutions for RE in Africa. The book also presents various case studies from different African countries and regions, using various methods and tools for data collection and analysis. The book aims to fill the gaps in the existing literature and practice on RE in Africa and to contribute to the advancement of knowledge and practice on RE in Africa.
This final chapter suggests some policy implications and recommendations that can promote and speed up the deployment of renewable energy sources in Africa. Moreover, it identifies some research gaps that remain to be addressed by future studies on renewable energy and sustainable development in Africa and proposes some possible research questions that future researchers could address to advance our knowledge and practice in this field. The chapter aims to contribute to the understanding of the dynamics of renewable energy in Africa, as well as to the policy design and implementation for renewable energy development and integration in the continent.
Scenario-based models based on plausible and acceptable descriptions of the future have time and again been employed to study the effect of an evolving energy system. This study employed scenario-based modeling using the Long-Range Energy Alternatives Planning System (LEAP) to explore the dynamics of the energy transition to cleaner energy in the Nigerian household sector. Our analysis showed that the household sector has and will continue to contribute the largest share to the overall energy demand in Nigeria within the period under study (2010–2030). To achieve sustainable development and eradicate energy poverty within the Nigerian household sector an alternative energy transition scenario was explored. This scenario identified bottlenecks that could hinder the mainstreaming of Liquefied Petroleum Gas (LPG) to substitute traditional fuelwood in the household sector and modeled a possible future where these bottlenecks are tackled, and LPG becomes the fuel of choice within the household sector in Nigeria.
Background The study assessed the association between language interpreter need and availability on satisfaction with healthcare services and trust in healthcare professionals among resettled Syrian refugees in Ontario. Methods 540 Syrian refugee parents who had resided in Ontario for an average of four years and had at least one child less than 18 years of age were interviewed. Information about satisfaction and trust in healthcare was collected based on the two questions “How satisfied are you with the healthcare services you receive?” and “To what extent do you trust healthcare professionals in Canada?” Multiple linear regression was performed to evaluate the independent relationship between the need and availability of an interpreter with satisfaction with healthcare services and trust in healthcare professionals after adjusting for several factors. Results 49.1% of participants reported needing an interpreter when accessing healthcare services. Of those who needed an interpreter, 19.4% were always offered an interpreter, while 11.9% and 17.8% were sometimes and never provided with an interpreter, respectively. Needing an interpreter when seeking care and always being offered an interpreter was significantly associated with increased satisfaction with the healthcare services (Adjβ = 0.344; p= 0.038) and approached significance for increased trust in healthcare professionals (Adjβ = 0.317; p= 0.053). Conclusion Further efforts are needed to ensure interpreter availability across various healthcare settings to improve satisfaction with healthcare services and trust in healthcare professionals and to enhance health outcomes among the Syrian refugee population.
Using an ensemble of atmosphere–ocean general circulation models (AOGCMs) in an idealized climate change experiment, this study evaluates the contribution of different ocean processes to Arctic Ocean warming. On the AOGCM-mean, the Arctic Ocean warming is greater than the global ocean warming, both in the volume-weighted mean, and at most depths within the upper 2000 m. However, the uncertainty of Arctic Ocean warming is much larger than the uncertainty of global ocean warming. The Arctic warming is greatest a few 100 m below the surface and is dominated by the import of extra heat, which is added to the ocean at lower latitudes and is conveyed to the Arctic mostly by the large-scale barotropic ocean circulation. The change in strength of this circulation in the North Atlantic is relatively small and not correlated with the Arctic Ocean warming. The Arctic Ocean warming is opposed and substantially mitigated by the weakening of the Atlantic meridional overturning circulation (AMOC), though the magnitude of this effect has a large model spread. By reducing the northward transport of heat, the AMOC weakening causes a redistribution of heat from high latitudes to low latitudes. Within the Arctic Ocean, the propagation of heat anomalies is influenced by broadening of cyclonic circulation in the east and weakening of anticyclonic circulation in the west. On the model-mean, the Arctic Ocean warming is most pronounced in the Eurasian Basin, with large spread across the AOGCMs, and accompanied by subsurface cooling by diapycnal mixing and heat redistribution by mesoscale eddies.
Vigorous intermittent exercise can improve indices of glycemia in the 24 h postexercise period in apparently healthy individuals. We examined the effect of a single session of bodyweight exercise (BWE) on glycemic responses using continuous glucose monitoring (CGM) under controlled dietary conditions. Healthy inactive adults (n = 27; 8 males, 19 females; age: 23 ± 3 years) completed 2 virtually supervised trials spaced ~ 1 week apart in a randomized, crossover manner. The trials involved an 11-min BWE protocol that consisted of 5 × 1-min bouts performed at a self-selected pace interspersed with 1-min active recovery periods or a non-exercise sitting control period (CON). Mean heart rate during the BWE protocol was 147 ± 14 beats per min (75% of age-predicted maximum). Mean 24 h glucose after BWE and CON was not different (5.0 ± 0.4 vs 5.0 ± 0.5 mM respectively; p = 0.39). There were also no differences between conditions for measures of glycemic variability or the postprandial glucose responses after ingestion of a 75 g glucose drink or lunch, dinner, and breakfast meals. This study demonstrates the feasibility of conducting a remotely supervised BWE intervention using CGM under free-living conditions. Future studies should investigate the effect of repeated sessions of BWE training or responses in people with impaired glycemic control.
Background Black North American communities have been disproportionately affected by COVID-19. These data have been largely based on case counts, hospitalizations and mortality data. Serologic testing enables a more complete determination of infection burden by documenting infection in persons with symptomatic as well as asymptomatic infection. We used serologic testing to determine the extent to which SARS-CoV-2 had penetrated into the Black community. We examined risk factors associated with seropositivity, including the presence of medical comorbidities and the social determinants of health. Methods We conducted a cross-sectional survey in a COVID-19 high-prevalence zone in Ontario along with 2 areas that have lower rates of COVID-19 cases. SARS-CoV-2 IgG antibodies were determined using the EUROIMMUN assay. The study samples were collected between August 15, 2020, and December 15, 2020 prior to the deployment of COVID-19 vaccines. Proportions were compared using Fishers Exact test or chi-square; potential risk factors were examined using a multiple logistic regression approach. Results Among 387 evaluable subjects, the majority, 274 (70.8%) were enrolled from northwest Greater Toronto Area (GTA) and adjoining suburban areas of Peel, Ontario with a high proportion of Black residents. The seropositivity rates for the lower prevalence areas (Oakville and London, Ontario) were comparable (3.3% (2/60; 95% CI 0.4-11.5) and 3.9% (2/51; 95% CI 0.5-13.5), respectively). The seropositivity rate for the northwest GTA was 12.6% (26/206); RR 3.5, 95% CI 1.3-9.8). Persons under the age of 19 years had the highest seropositivity rate (10/50; 20.0%, 95% CI 10.3-33.7%). Front-line workers were greater than 3 times more likely to be seropositive compared with non-frontline workers (13.0 vs 3.2%; p=.01; RR 3.3 (95% CI 1.3 – 8.3). There was an interaction effect between race and location of residence as this relates to the relative risk of seropositivity. Conclusion During the pre-vaccine phase of the COVID-19 pandemic, the seropositivity rate for SARS-CoV-2 within a COVID-19 high-prevalence area was 3-fold greater than lower prevalence areas of Ontario, Canada. The data help to define the burden of COVID-19 within a community with a high proportion of Black residents compared with other communities. Disclosures All Authors: No reported disclosures
A new measurement of inclusive-jet cross sections in the Breit frame in neutral current deep inelastic scattering using the ZEUS detector at the HERA collider is presented. The data were taken in the years 2004–2007 at a centre-of-mass energy of $$318\,\,\textrm{GeV}$$ 318 GeV and correspond to an integrated luminosity of $$347\,\,\textrm{pb}^{-1}$$ 347 pb - 1 . The jets were reconstructed using the $$k_t$$ k t -algorithm in the Breit reference frame. They have been measured as a function of the squared momentum transfer, $$Q^2$$ Q 2 , and the transverse momentum of the jets in the Breit frame, $$p_{\perp ,\text {Breit}}$$ p ⊥ , Breit . The measured jet cross sections are compared to previous measurements and to perturbative QCD predictions. The measurement has been used in a next-to-next-to-leading-order QCD analysis to perform a simultaneous determination of parton distribution functions of the proton and the strong coupling, resulting in a value of $$\alpha _s(M_Z^2) = 0.1142 \pm 0.0017 \text {~(experimental/fit)}$$ α s ( M Z 2 ) = 0.1142 ± 0.0017 (experimental/fit) $${}_{-0.0007}^{+0.0006} \text {~(model/parameterisation)}$$ - 0.0007 + 0.0006 (model/parameterisation) $${}_{-0.0004}^{+0.0006} \text {~(scale)}$$ - 0.0004 + 0.0006 (scale) , whose accuracy is improved compared to similar measurements. In addition, the running of the strong coupling is demonstrated using data obtained at different scales.
This paper contributes to the existing stock market anomaly literature by being the first to analyze the benefits of combining two distinct anomalies; specifically, the low-volatility and mean-reversion anomalies. Our results show that on a long-only basis, these two time-varying anomalies could be combined into a double-sort investment strategy that includes some desirable characteristics from each of them, thereby making the portfolio return accumulation more stable over time. As the added-value of low-volatility investing stems mostly from the risk-reduction side, while contrarian stocks are generally highly volatile with remarkable upside potential, the use of the double-sort portfolio-formation in which the contrarian stocks are picked from the sub-set of below-median volatility stocks can shorten the below-market performance periods that have occasionally materialized for plain low-volatility or plain contrarian investors.
Two nonexperimental studies were conducted to test how and why transgression victims’ narcissism influences their grudge holding, using undergraduate students and a community sample of adults, respectively. Study 1 tested the association between victims’ vulnerable narcissism and grudge holding, including emotional persistence, perceived longevity, and disdain toward the transgressor. It also tested the extent to which victims’ grandiose narcissism moderated the association. Study 2 was conducted to replicate Study 1 and test whether victims’ rumination about the transgression mediated the moderated association. Overall, those with higher degrees of grandiosity showed a positive relation between vulnerable narcissism and reported emotional persistence (Studies 1 and 2) and perceived longevity (Study 2). Finally, rumination explained the moderated relation (Study 2).
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19,977 members
Elsabeth Jensen
  • School of Nursing
Mary Leigh Morbey
  • Faculty of Education
Sharon Murphy
  • Faculty of Education
A K M Alamgir
  • Faculty of Liberal Arts and Professional Studies
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