5,885 research outputs found

    Development of Porous Rubber Pavement for the Canadian Climate

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    Permeable pavement usage in North America has increased over the last decade as a viable stormwater management system. Porous Rubber Pavement (PRP) is a new material in this category which has been currently utilized as a pavement surface material for low-traffic areas and pedestrian walkways. This material consists of recycled crumb rubber aggregates, granite aggregates and polyurethane as a binder and is proportioned to attain a very high percentage of interconnected air voids (up to 45%). As a new pavement material in North America, the properties and performance of PRP are not thoroughly understood for cold climate conditions. This research aimed to understand the properties and performance of PRP and improve its performance as a pavement surface material for the Canadian climate. This objective is achieved through an evaluation of existing sites and mixes, developing new mixes through an experimental design process, and evaluating new mixes in the laboratory facilities. Some of the mixes were selected to apply in the trial section to assess field performance. Finally, recommendations and guidelines are developed for this climatic zone. Through the experimental design, four new mixes were developed using different proportions of stone aggregates, rubber aggregates and polyurethane binder. Also, using the proportion of the Control Mix, four polyurethane binders were used to make four different mixes to determine the different binder effects in PRPs. In the next stage of research, two trial sections were constructed using selected mixes along with the Control Mix. In addition, samples were also prepared from the field mixes to test their properties in the laboratory. Then the field performance of the various mixes was evaluated over a series of months. They were initially tested immediately following construction before fully opening for traffic. Then three weeks after construction and after seven months when the sections had experienced their first winter. Preliminary field investigations showed that with the current commercial mix, the achieved elastic modulus of PRP surfaces ranged between 37 MPa and 33 MPa. Besides, frictional values ranged between 57 BPN and 74 BPN. Higher IRI values were calculated for both sites, ranging between 7.56 m/km to 15.77 m/km. The average infiltration rate for the pavement surface areas was found to be 30836 mm/hr. The mechanical properties and durability of the Control Mix and newly developed mixes were investigated. The tensile and compressive strength of the mixes were found to be higher when the percentages of stone aggregates and binders were increased in the mixes. Additionally, an increase in air voids in the samples reduced the materials' tensile and compressive strength. Concerning the types of binder and sources, the obtained results showed no considerable influence of different types of binder in compressive strength test results, whereas binder sources influenced the tensile strength of the PRP materials. PRP samples with varying compositions retained more than 70% of their tensile strength after conditioning with five freeze-thaw cycles. However, due to the variety of binders used, retained tensile strength for PRP samples varied, and some showed retained tensile strength below 70%. The durability study showed that the granite stones that were used for all the sample preparation were not strong enough to withstand higher abrasion loss. However, PRPs with different compositions showed good rutting resistance, ranging from 0.3mm to 2.8mm in different mixes. Moisture-induced damage, stripping related abrasion was also found to be very small in PRP mixes, ranging from 2.6% to 0.1%. Also, the use of different binders from different sources showed that the B2—aliphatic binder could withstand more rutting than other binders. A Los Angeles abrasion tester tested unconditioned and conditioned samples to determine the materials' ravelling resistance. The result showed that abrasion loss increased in the samples after conditioning with five freeze-thaw cycles. However, it was consistent with the mix types. On the other hand, abrasion loss of samples with different binders occurred differently in the conditioned and unconditioned situations and was inconsistent in the mixes. Subgrade samples were collected from sites A and B during the trial section construction. The bearing capacity of subgrade soil for Site B was found to be higher than that of Site A. Subsequently, the performance of the mixes in the sections was evaluated through a series of field testing. The LWD results showed that the stiffness modulus differed for the same mixes at Site A and Site B. Besides, all the mixes showed higher stiffness in the 2nd field test than the 1st since compaction occurred on the pavement after opening for traffic. Nevertheless, after experiencing their first winter, a reduction in stiffness was observed for all mixes in the 3rd test. The BPT test revealed that a higher frictional value of PRP mixes was associated with a higher percentage of rubber aggregates and a lower percentage of binder in the mixes. At the same time, a reduction in BPN values was observed in the 2nd test than in the 1st since the sections were further compacted and polished after opening for traffic. In addition, the surface ravelling and transported loose particles affected the frictional values in the 3rd test, increasing the BPN numbers. Initial rut depths on Site A for different mixes ranged from -7.0 mm to -8.7mm, and the range was -5.8 mm to -10.7mm for Site B. However, after fully opening for traffic, greater rut depths were observed on each section due to the additional compaction under the wheel paths. The permeability of the PRP sections ranged from 28368 mm/h to 45605 mm/h, which is higher than the highest rainfall rate in Canada (298.8 mm/h). However, most of the sections showed higher permeability in the 2nd test. After the first winter, the permeability of some of the sections was found to be further increased, whereas others were found to be decreased due to the influence of site surroundings. In the 1st and 2nd field tests, no visible surface distress was observed at Site A and Site B. A small amount of surface distress was observed after the first winter (seven months after the construction), which included a slight loss of coarse aggregate, minor ravelling, small cracking, and rutting. Throughout the trial section construction process, it was also observed that by improving the construction methods and making slight modifications during the construction process (like increased compaction), the performance of PRPs could be further enhanced. Finally, a set of recommendations and guidelines were developed for using the PRP in the Canadian climate

    A Decision Support System for Economic Viability and Environmental Impact Assessment of Vertical Farms

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    Vertical farming (VF) is the practice of growing crops or animals using the vertical dimension via multi-tier racks or vertically inclined surfaces. In this thesis, I focus on the emerging industry of plant-specific VF. Vertical plant farming (VPF) is a promising and relatively novel practice that can be conducted in buildings with environmental control and artificial lighting. However, the nascent sector has experienced challenges in economic viability, standardisation, and environmental sustainability. Practitioners and academics call for a comprehensive financial analysis of VPF, but efforts are stifled by a lack of valid and available data. A review of economic estimation and horticultural software identifies a need for a decision support system (DSS) that facilitates risk-empowered business planning for vertical farmers. This thesis proposes an open-source DSS framework to evaluate business sustainability through financial risk and environmental impact assessments. Data from the literature, alongside lessons learned from industry practitioners, would be centralised in the proposed DSS using imprecise data techniques. These techniques have been applied in engineering but are seldom used in financial forecasting. This could benefit complex sectors which only have scarce data to predict business viability. To begin the execution of the DSS framework, VPF practitioners were interviewed using a mixed-methods approach. Learnings from over 19 shuttered and operational VPF projects provide insights into the barriers inhibiting scalability and identifying risks to form a risk taxonomy. Labour was the most commonly reported top challenge. Therefore, research was conducted to explore lean principles to improve productivity. A probabilistic model representing a spectrum of variables and their associated uncertainty was built according to the DSS framework to evaluate the financial risk for VF projects. This enabled flexible computation without precise production or financial data to improve economic estimation accuracy. The model assessed two VPF cases (one in the UK and another in Japan), demonstrating the first risk and uncertainty quantification of VPF business models in the literature. The results highlighted measures to improve economic viability and the viability of the UK and Japan case. The environmental impact assessment model was developed, allowing VPF operators to evaluate their carbon footprint compared to traditional agriculture using life-cycle assessment. I explore strategies for net-zero carbon production through sensitivity analysis. Renewable energies, especially solar, geothermal, and tidal power, show promise for reducing the carbon emissions of indoor VPF. Results show that renewably-powered VPF can reduce carbon emissions compared to field-based agriculture when considering the land-use change. The drivers for DSS adoption have been researched, showing a pathway of compliance and design thinking to overcome the ‘problem of implementation’ and enable commercialisation. Further work is suggested to standardise VF equipment, collect benchmarking data, and characterise risks. This work will reduce risk and uncertainty and accelerate the sector’s emergence

    Implementing Health Impact Assessment as a Required Component of Government Policymaking: A Multi-Level Exploration of the Determinants of Healthy Public Policy

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    It is widely understood that the public policies of ‘non-health’ government sectors have greater impacts on population health than those of the traditional healthcare realm. Health Impact Assessment (HIA) is a decision support tool that identifies and promotes the health benefits of policies while also mitigating their unintended negative consequences. Despite numerous calls to do so, the Ontario government has yet to implement HIA as a required component of policy development. This dissertation therefore sought to identify the contexts and factors that may both enable and impede HIA use at the sub-national (i.e., provincial, territorial, or state) government level. The three integrated articles of this dissertation provide insights into specific aspects of the policy process as they relate to HIA. Chapter one details a case study of purposive information-seeking among public servants within Ontario’s Ministry of Education (MOE). Situated within Ontario’s Ministry of Health (MOH), chapter two presents a case study of policy collaboration between health and ‘non-health’ ministries. Finally, chapter three details a framework analysis of the political factors supporting health impact tool use in two sub-national jurisdictions – namely, Québec and South Australia. MOE respondents (N=9) identified four components of policymaking ‘due diligence’, including evidence retrieval, consultation and collaboration, referencing, and risk analysis. As prospective HIA users, they also confirmed that information is not routinely sought to mitigate the potential negative health impacts of education-based policies. MOH respondents (N=8) identified the bureaucratic hierarchy as the brokering mechanism for inter-ministerial policy development. As prospective HIA stewards, they also confirmed that the ministry does not proactively flag the potential negative health impacts of non-health sector policies. Finally, ‘lessons learned’ from case articles specific to Québec (n=12) and South Australia (n=17) identified the political factors supporting tool use at different stages of the policy cycle, including agenda setting (‘policy elites’ and ‘political culture’), implementation (‘jurisdiction’), and sustained implementation (‘institutional power’). This work provides important insights into ‘real life’ policymaking. By highlighting existing facilitators of and barriers to HIA use, the findings offer a useful starting point from which proponents may tailor context-specific strategies to sustainably implement HIA at the sub-national government level

    Responsible E-Waste Value Chains in Africa

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    Population growth, increasing prosperity and changing consumer habits globally are increasing demand for consumer electronics. Further to this, rapid changes in technology, falling prices, increased affordability and consumer appetite for new products have exacerbated e-waste management challenges and seen millions of tons of electronic devices become obsolete. This rapid literature review collates evidence from academic, policy focussed and grey literature on e-waste value chains. The report should be read I conjunction with an earlier report on e-waste management. E-waste is any electrical or electronic equipment, including all components, subassemblies and consumables, which are part of the equipment at the time the equipment becomes waste. When e-waste is collected and treated formally, it normally includes the following steps: Collection, Sorting and disassembly, Size reduction, Separation. The following five pillars of a sustainable e-waste management system have been identified: • Business and finance • Policy and regulation • Technology and skills • Monitoring and control • Marketing and awareness As such, to support the development of a responsible e-waste value chain, the following elements must be addressed. • Understanding how e-waste is currently managed • There is no one-size-fits all solution to building a robust e-waste management system based on extended producer responsibility. • An e-waste system built without a participatory approach is likely to be hampered by a series of issues. • An overarching policy is necessary • The choices made for the sector should be founded on two crucial elements – data from on the ground, and inputs from stakeholders. • Enforcement is incumbent on the government mandate The push towards a circular economy has provided stakeholders across the value chain with an impetus to initiate systemic improvements and invest in infrastructure and awareness raising.FCDO (Foreign, Commonwealth and Development Office

    On the Mechanism of Building Core Competencies: a Study of Chinese Multinational Port Enterprises

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    This study aims to explore how Chinese multinational port enterprises (MNPEs) build their core competencies. Core competencies are firms’special capabilities and sources to gain sustainable competitive advantage (SCA) in marketplace, and the concept led to extensive research and debates. However, few studies include inquiries about the mechanisms of building core competencies in the context of Chinese MNPEs. Accordingly, answers were sought to three research questions: 1. What are the core competencies of the Chinese MNPEs? 2. What are the mechanisms that the Chinese MNPEs use to build their core competencies? 3. What are the paths that the Chinese MNPEs pursue to build their resources bases? The study adopted a multiple-case study design, focusing on building mechanism of core competencies with RBV. It selected purposively five Chinese leading MNPEs and three industry associations as Case Companies. The study revealed three main findings. First, it identified three generic core competencies possessed by Case Companies, i.e., innovation in business models and operations, utilisation of technologies, and acquisition of strategic resources. Second, it developed the conceptual framework of the Mechanism of Building Core Competencies (MBCC), which is a process of change of collective learning in effective and efficient utilization of resources of a firm in response to critical events. Third, it proposed three paths to build core competencies, i.e., enhancing collective learning, selecting sustainable processes, and building resource base. The study contributes to the knowledge of core competencies and RBV in three ways: (1) presenting three generic core competencies of the Chinese MNPEs, (2) proposing a new conceptual framework to explain how Chinese MNPEs build their core competencies, (3) suggesting a solid anchor point (MBCC) to explain the links among resources, core competencies, and SCA. The findings set benchmarks for Chinese logistics industry and provide guidelines to build core competencies

    A Molecular Approach to the Diagnosis, Assessment, Monitoring and Treatment of Pulmonary Non-Tuberculous Mycobacterial Disease

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    Introduction: Non-Tuberculous Mycobacteria (NTM) can cause disease of the lungs and sinuses, lymph nodes, joints and central nervous system as well as disseminated infections in immunocompromised individuals. Efforts to tackle infections in NTM are hampered by a lack of reliable biomarkers for diagnosis, assessment of disease activity, and prognostication. Aims: The broad aims of this thesis are: 1. to develop molecular assays capable of quantifying the 6 most common pathogenic mycobacteria (M. abscessus, M. avium, M. intracellulare, M. malmoense, M. kansasii, M. xenopi) and calculate comparative sensitivities and specificities for each assay. 2. to assess patients’ clinical course over 12 – 18 months by performing the developed molecular assays against DNA extracted from sputum from patients with NTM infection. 3. to assess dynamic bacterial changes of the lung microbiome in patients on treatment for NTM disease and those who are treatment na ve. Methods: DNA was extracted from a total of 410 sputum samples obtained from 38 patients who were either: • commencing treatment for either M. abscessus or Mycobacterium avium complex. • considered colonised with M. abscessus or Mycobacterium avium complex (i.e. cultured NTM but were not deemed to have infection as they did not meet ATS or BTS criteria for disease). • Diagnosed with cystic fibrosis (CF) or non-CF bronchiectasis but had never cultured NTM. For the development of quantitative molecular assays, NTM hsp65 gene sequences were aligned and interrogated for areas of variability. These variable regions enabled the creation of species specific probes. In vitro sensitivity and specificity for each probe was determined by testing each probe against a panel of plasmids containing hsp65 gene inserts from different NTM species. Quantification accuracy was determined by using each assay against a mock community containing serial dilutions of target DNA. Each sample was tested with the probes targeting: M. abscessus, M. avium and M. intracellulare producing a longitudinal assessment of NTM copy number during each patient’s clinical course. In addition, a total of 64 samples from 16 patients underwent 16S rRNA gene sequencing to characterise longitudinal changes in the microbiome of both NTM disease and controls. Results: In vitro sensitivity for the custom assays were 100% and specificity ranged from 91.6% to 100%. In terms of quantification accuracy, there was no significant difference between the measured results of each assay and the expected values when performed in singleplex. The assays were able to accurately determine NTM copy number to a theoretical limit of 10 copies/μl. When used against samples derived from human sputum and using culture results as a gold standard, the sensitivity of the assay for M. abscessus was found to be 0.87 and 0.86 for MAC. The specificity of the assay for M. abscessus was 0.95 and 0.62 for MAC. The negative predictive value of the assay for M. abscessus was 0.98 and 0.95 for MAC. This resulted in an AUC of 0.92 for M. abscessus and 0.74 for MAC. Longitudinal analysis of the lung microbiome using 16SrRNA gene sequencing showed that bacterial burden initially decreases after initiation of antibiotic therapy but begins to return to normal levels over several months of antibiotic therapy. This effect is mirrored by changes in alpha diversity. The decrease in bacterial burden and loss of alpha diversity was found to be secondary to significant changes in specific genera such as Veillonella and Streptococcus. The abundance of other Proteobacteria such as Pseudomonas remain relatively constant. Conclusion: The molecular assay has shown high in vitro sensitivity and specificity for the detection and accurate quantification of the 6 most commonly pathogenic NTM species. The assays successfully identified NTM DNA from human sputum samples. A notable association between NTM copy number and the cessation of one or more antibiotics existed (i.e. when one antibiotic was stopped because of patient intolerance, NTM copy number increased, often having been unrecordable prior to this). The qPCR assays developed in this thesis provide an affordable, real time and rapid measurement of NTM burden allowing clinicians to act on problematic results sooner than currently possible. There was no significant difference between the microbiome in bronchiectasis and cystic fibrosis nor was there a significant difference between the microbiome in patients requiring treatment for NTM and those who did not. Patients receiving treatment experienced an initial decrease in bacterial burden over the first weeks of treatment followed by a gradual increase towards baseline over the next weeks to months. This change was mirrored in measures of alpha diversity. Changes in abundance and diversity were accounted for by decreases in specific bacteria whilst the abundance of other bacteria increased, occupying the microbial niche created. These bacteria (for example Pseudomonas spp) are often associated with morbidity.Open Acces

    World Development Report 2022

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    This new World Development Report focuses on the interrelated economic risks that households, businesses, financial institutions, and governments worldwide are facing as a consequence of the COVID-19 crisis. The Report offers new insights from research on the interconnectedness of balance sheets and the potential spillover effects across sectors. It also offers policy recommendations based on these insights. Specifically, it addresses the question of how to reduce the financial risks stemming from the extraordinary policies adopted in response to the COVID-19 crisis while supporting an equitable recovery. The unfolding COVID-19 pandemic has already led to millions of deaths, job losses, business failures, and school closings, triggering the most encompassing economic crisis in almost a century. Poverty rates have soared and inequality has widened both across and within countries. Disadvantaged groups that had limited financial resilience to begin with and workers with lower levels of education—especially younger ones and women— have been disproportionately affected. The response by governments has included a combination of cash transfers to households, credit guarantees for firms, easier liquidity conditions, repayment grace periods for much of the private sector, and accounting and regulatory forbearance for many financial institutions. Although these actions have helped to partially mitigate the economic and social consequences of the pandemic, they have also resulted in elevated risks, including public overindebtedness, increased financial fragility, and a general erosion in transparency. Emerging economies have been left with very limited fiscal space, and they will be made even more vulnerable by the impending normalization of monetary policy in advanced economies. This Report highlights several priority areas for action. First is the need for early detection of significant financial risks. Because the balance sheets of households, firms, financial sector institutions, and governments are tightly interrelated, risks may be hidden. The share of nonperforming loans has generally remained below what was feared at the beginning of the crisis. But this could be due to forbearance policies that delayed debt repayments and relaxed accounting standards. Firm surveys in emerging economies reveal that many businesses expect to be in payment arrears in the coming months, and so private debt could suddenly become public debt, as in many past crises. The interdependence of economic policies across countries matters as well. Public debt has reached unprecedented levels. As monetary policy tightens in advanced economies, interest rates will need to increase in emerging economies as well, and their currencies will likely depreciate. Higher interest rates make debt service more expensive, reinforcing the trend of recent years, and weaker currencies make debt service more burdensome relative to the size of the economy. Liquidity problems could suddenly morph into solvency problems

    Consolidation of Urban Freight Transport – Models and Algorithms

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    Urban freight transport is an indispensable component of economic and social life in cities. Compared to other types of transport, however, it contributes disproportionately to the negative impacts of traffic. As a result, urban freight transport is closely linked to social, environmental, and economic challenges. Managing urban freight transport and addressing these issues poses challenges not only for local city administrations but also for companies, such as logistics service providers (LSPs). Numerous policy measures and company-driven initiatives exist in the area of urban freight transport to overcome these challenges. One central approach is the consolidation of urban freight transport. This dissertation focuses on urban consolidation centers (UCCs) which are a widely studied and applied measure in urban freight transport. The fundamental idea of UCCs is to consolidate freight transport across companies in logistics facilities close to an urban area in order to increase the efficiency of vehicles delivering goods within the urban area. Although the concept has been researched and tested for several decades and it was shown that it can reduce the negative externalities of freight transport in cities, in practice many UCCs struggle with a lack of business participation and financial difficulties. This dissertation is primarily focused on the costs and savings associated with the use of UCCs from the perspective of LSPs. The cost-effectiveness of UCC use, which is also referred to as cost attractiveness, can be seen as a crucial condition for LSPs to be interested in using UCC systems. The overall objective of this dissertation is two-fold. First, it aims to develop models to provide decision support for evaluating the cost-effectiveness of using UCCs. Second, it aims to analyze the impacts of urban freight transport regulations and operational characteristics on the cost attractiveness of using UCCs from the perspective of LSPs. In this context, a distinction is made between UCCs that are jointly operated by a group of LSPs and UCCs that are operated by third parties who offer their urban transport service for a fee. The main body of this dissertation is based on three research papers. The first paper focuses on jointly-operated UCCs that are operated by a group of cooperating LSPs. It presents a simulation model to analyze the financial impacts on LSPs participating in such a scheme. In doing so, a particular focus is placed on urban freight transport regulations. A case study is used to analyze the operation of a jointly-operated UCC for scenarios involving three freight transport regulations. The second and third papers take on a different perspective on UCCs by focusing on third-party operated UCCs. In contrast to the first paper, the second and third papers present an evaluation approach in which the decision to use UCCs is integrated with the vehicle route planning of LSPs. In addition to addressing the basic version of this integrated routing problem, known as the vehicle routing problem with transshipment facilities (VRPTF), the second paper presents problem extensions that incorporate time windows, fleet size and mix decisions, and refined objective functions. To heuristically solve the basic problem and the new problem variants, an adaptive large neighborhood search (ALNS) heuristic with embedded local search heuristic and set partitioning problem (SPP) is presented. Furthermore, various factors influencing the cost attractiveness of UCCs, including time windows and usage fees, are analyzed using a real-world case study. The third paper extends the work of the second paper and incorporates daily and entrance-based city toll schemes and enables multi-trip routing. A mixed-integer linear programming (MILP) formulation of the resulting problem is proposed, as well as an ALNS solution heuristic. Moreover, a real-world case study with three European cities is used to analyze the impact of the two city toll systems in different operational contexts
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