The Strategy Simulator project, funded by the Federal Aviation Administration (FAA), strives to find a tax structure that will support the National Airspace System (NAS) and maintain revenue neutrality, where taxes can be adjusted and the FAA can still attain the same revenue amount if taxes had not changed. Virginia Tech's role in the project is to analyze the effects of different tax structures on passenger demand. Virginia Tech focuses on ticket and segment taxes and runs different tax scenarios through the Transportation Systems Analysis Model (TSAM) and the TSAM Aggregation for the Strategy Simulator (TASS) model. TSAM provides a more microscopic analysis of demand by including spatial representation and mode choice in the model. TASS is a work in progress that aggregates the TSAM analysis in order to reduce computation time so that scenarios can be tested quickly. Based on data from literature review, TSAM results provides the smallest combined percent error for demand and revenue, followed by TASS, then the Strategy Simulator. TSAM and TASS also provide a detailed analysis of demand behavior in response to tax changes. In general, demand decreases as taxes increase, and demand increases over the years due to a fare scaling factor applied to reduce fares over the years. Revenue increases both over increasing taxes and over the years, indicating that increases in taxes does not harm revenue collection and actually increases revenues for the ticket and segment taxes tested. Revenue increases over the years because demand increases over the years, and the revenue generated from this increased demand more than makes up for decreased fares. / Master of Science

No / Optimal design (vapour load, V and number of stages, N) and operation (reflux ratio, R and batch time, tb) of batch distillation have received significant attention in recent years. In these studies, it has been suggested that V should be set at some upper limit (thought to be optimum) and the optimisation task should be focused on finding the optimum values of N, R and tb, which would minimise the capital investment while maximising an economic objective function usually the profit (P). The major drawback of such optimisation strategy is that there is no constraint on the amount of product (on specification) being produced (NB = no. of batches in a given time) and the overall profit can only be maximised by producing unlimited amount of products. Unplanned and unlimited production of products are not sustainable and may lead to significant losses in the case of large inventory requirements of any excess products produced. In this work, for the first time, the optimal design and operation task for batch distillation is considered with due regards to the market demands (small to large number of batches) of the products being produced. An optimisation problem formulation is presented for the task which is different than those used in the past under unlimited product demand scenario. Simulated Annealing type algorithm is used for the solution of the optimisation problem. With several examples, it will be shown that fixing V a priori (say V < Vopt) will not allow production of NB batches of products with any combination of (N, R, tb) in a given production time. Also it will be shown that with V fixed at say V > Vopt, P will always be <Pmax for any combination of (N, R, tb). The comparisons between the results with and without fixing of V a priori show very clear improvement in the annual profit.

Vid undervisning i matematik är det vanligt att undervisningen i stor utsträckning baseras på ett läromedel, både för lärarens teoribeskrivningar och vid elevernas enskilda arbete med uppgiftslösning. Det är därför viktigt att uppgifterna i läromedlet är utformade så att eleven kan utveckla de kunskapersom läroplanen föreskriver. I Sverige, liksom i flera andra länder i framförallt Europa och USA, beskrivs dessa matematiska kunskaper i termer av olika typer av förmågor. Elevers färdigheter i en viss förmåga utvecklas då eleven utför uppgifter där den specifika förmågan aktiveras på en nivå som innebär en kognitiv utmaning. Den önskvärda nivån på den kognitiva utmaningen beror på den enskilda elevens förkunskaper och förutsättningar. För att möjliggöra att alla elever skall kunna utveckla samtliga de efterfrågade förmågorna är det nödvändigt att läromedlet innehåller uppgifter med varierande nivå av kognitiv utmaning där samtliga förmågor aktiveras. Utredningar och studier från myndigheter och forskare antyder att undervisningen saknar den önskvärda variationen utan till stor del uppehåller sig vid procedurkunskap och tillämpningar av algoritmer. I syfte att undersöka variationen i nivå på kognitiv utmaning undersöker detta examensarbeteuppgifter inom området andragradsekvationer ur tre olika svenskspråkiga läromedel. Nivån på den kognitiva utmaningen definieras i denna studie som antalet olika former av svårigheter en uppgift innehåller. Den ökade kognitiva utmaningen består således i att fler förmågor aktiveras i samma uppgift. Analysen visar en majoritet av uppgifterna i samtliga läromedel har en låg nivå av kognitiv utmaning som inte erbjuder möjlighet för eleven att utveckla samtliga matematiska förmågor. Dessutomär antalet uppgifter av hög kognitiv nivå låg, så även vid ett aktivt urval av uppgifter av läraren är begränsas möjligheten till variation av läromedlen. Detta resultat är i linje med resultat från tidigareforskning. / When teaching mathematics, it is common that classroom activities to a large extent follow a textbook, both for the teacher’s presentations and for the students’ individual work on tasks. It is therefore important that the textbook is structured in a way that adheres to the requirements of the curricula. In Sweden, as well as in several other countries in primarily Europe and the US, mathematical knowledge is expressed in the form of different kind of capabilities or competencies. Students’ level of knowledge of a specific competence evolves from performing tasks with a cognitive demand to activate that competence. The desirable level of cognitive demand depends on the individual student’s ability and prior knowledge. To enable all students to develop all the required competencies, it is important that the textbook contains tasks with a varying level of cognitive demand where every competency is activated. Reports and studies from authorities and scientist indicate that classroom instruction often lack the desirable variation and instead focus on procedural knowledge and application of algorithms to a large degree. With the aim to study the variation of the level of cognitive demand this degree project investigates tasks on the subject of quadratic equations from three different upper secondary school textbooks written in Swedish. The level of cognitive demand is in this study defined as the number of different types ofdifficulties a task contains. A higher level of cognitive demand is thus interpreted as more competencies being activated in a single task. The analysis shows that majority of the tasks in all the textbooks have a low level of cognitive demand that do not offer opportunities for the student to evolve all the required competencies. In addition, the number of tasks with a high level of cognitive demand is low, restricting the possibility for the teacher to actively choose appropriate tasks from the textbook alone. This result is in line with earlier similar studies.

This thesis describes and discusses the application of System Dynamics methodology as a basis for formulating diversification strategy and control policies of the largest diversifying cement company in the 'United Kingdom. The problems of the industry such as stagnant growth, cyclic and seasonal variations in cement demand, and overcapacity are described. The formulation of a SD model of the situation which captures these problems together with its equations system are presented. The model also simulates the planning and control processes for the selection, initiation and completion of both expansion and diversification investment projects. It is argued and demonstrated that the fact that these processes consist of feedback loops should and could be utilized for understanding these processes, advancing complementary theoretical concepts, and designing and formulating more 'effective systems and decision rules. An intensive analysis of the model in SD frameworks further supports these arguments. These analyses reveal the nature of the system's dynamic properties and its likely developments, the dynamic and situational nature of diversification effectiveness, and the importance of several diversification decision factors. These analyses also show how complex the formulation of a thorough and effective diversification strategy may become together with the ways and means of dealing with these complexities.. It is concluded that the thrust of an effective diversification lies with the broadening of the conventional theoretical concepts and analysis to include the dynamic characteristics of the system. It is also concluded and shown that System Dynamics methodology can provide a strong analytical basis for achieving these ends.

<p> The Objective of this study is to investigate analytically the impact of certain technological and market conditions on the optimum location of the firm. The existing location models may be divided into those which consider both supply and demand aspects and those which concentrate on supply factors alone. Traditionally, the former group of models define equilibrium as the profit maximizing location and assume both a linear-homogeneous production function and a linear demand function. The latter class of models assume only the linear-homogeneity of production, and equilibrium is found at the cost-minimizing site.</p> <p> In this paper two cases are examined. Firstly, the influence of a general non-linear homogeneous production function on a simple cost minimizing model is considered. Secondly, the effect of non-linear demand functions and non-linear homogeneous technology on a profit maximizing model are assessed. The results indicate that the optimum location in the cost minimizing situation does not vary with the level of output, whatever the degree of homogeneity of the production function. This directly contradicts the common belief regarding the effects of production. Furthermore, in the profit-maximizing problem, and with non-linear homogeneous production, the solution is unaffected by the shape of the demand function.</p> <p> Suggestions for refining and extending this analysis include the use of general rather than specific demand, transportation and production functions: the employment of exhaustible inputs, and generalization to the three-dimensional situation.</p> / Thesis / Master of Arts (MA)

No description available.

The benefits of occupational therapy (OT) intervention for children with disabilities are numerous and impactful. Among many other advantages, OT can help children to develop their functional living skills, form relationships with others, improve in motor co-ordination, and transition to adulthood (American Occupational Therapy Association [AOTA], 2015). Restricted access to treatment, therefore, can deprive the child, and his or her family of the opportunities to reach their fullest potential. In Trinidad, pediatric occupational therapy is available at private clinics at great costs to families. This is incongruous with the healthcare climate of the nation, in which public-sector care is offered free of charge. Unfortunately, there are no pediatric Governmental OT positions available. Families who cannot afford OT simply will have no access to the services. Three major explanations for the lack of public-sector OT could potentially include doubts of the demand for OT, lack of qualified therapists in the country, and the inability to supply necessary space and equipment. Project Kids CLUB responds to each of these concerns. Primary research demonstrates the irrefutable desire for services, the local Master of Occupational Therapy program provides sufficient staff, and past attempts to begin such a unit resulted in designated space and materials at the Eric William’s Medical Sciences Complex (EWMSC), a public-sector hospital in Trinidad. The realization of Project Kids CLUB has the potential to change the landscape of pediatric care for children and families, the Government, and occupational therapists. Families will benefit from free access to quality care that can increase participation, quality of life and wellbeing. The Government will meet an important societal need, as well as fulfill some of its promises to human rights treaties. Occupational therapists will have the opportunity to impact the public-sector and serve one of the most vulnerable groups of clients. The information presented in this project will be disseminated to the target audiences to raise awareness of pediatric OT in hopes that one day, the proposed Centre for Learning and Understanding Behavior (CLUB) may come to fruition. Findings demonstrate that there is demand for and benefits of pediatric occupational therapy, as well as a realistic means of establishing a unit. This project demonstrates that there is no excuse for the lack of services, and no excuse for any child to be left without access to occupational therapy intervention. / 2019-07-06T00:00:00Z

Urban charter schools serving economically disadvantaged minority communities experience high teacher attrition. This study examined the association between high-demand teachers, school working conditions, and turnover, both voluntary departures and involuntary terminations in an urban, charter school district. I found that improved working conditions were associated with a decrease in the odds of leaving, but this significant association only applied to departures, not terminations. Despite this effect of working conditions on turnover, working conditions did not moderate the effect of high-demand turnover in any model. Regarding high-demand teachers, I found that special educators and teachers of color were less likely to leave than non-special educators and non-teachers of color when accounting for working conditions and controlling for teacher and school characteristics. When examining departures versus terminations, teachers of color were less likely to depart from their teaching positions, and special educators were less likely to be terminated. In general, STEM teachers were more likely to leave the organization than non-STEM teachers, but this finding was not significant. / School Psychology

The shadow economy is a topic that has been around for many years now. The increasing regulations on cash and the endeavours public authorities made to enlarge the tax base show a clear intention from the public sector to pursue any activity that is carried out outside the borders of what is taxable. This paper uses the Currency Demand Approach (CDA) to estimate the monetary base M0 for Portugal, Italy, Greece, and Spain and for each year from 2002 to 2021 and, subsequently, calculate the size of the shadow economy as a percentage of GDP. To estimate the CDA equation, we employed fixed effects panel data regression. The results show an average shadow economy value of 9,33% for Greece; 13,43% for Italy; 10,78% for Portugal; and 11,11% for Spain. The results have also been compared with those of previous studies that have estimated the shadow economy of other countries using the MIMIC approach, showing that the CDA tends to give lower estimates. Additionally, a common trend was found for the studied countries since after the financial crisis of 2008 and 2014, all of them reached peak values in their shadow economies.

Stress utgör en välkänd utmaning inom polisyrket. Kombinationen av höga arbetskrav och otillräckliga resurser ökar risken för psykiska påfrestningar. Syftet med denna studie är att undersöka hur relativt nyanställda svenska poliser i yttre tjänst upplever arbetsrelaterad stress samt vilka krav och påfrestningar de ställs inför. Dessutom ta reda på eventuella resurser som finns att hantera de krav som ställs. Åtta semistrukturerade intervjuer genomfördes med relativt nyutexaminerade poliser i Sverige som arbetade i yttre tjänst. En tematisk analys visade bland annat att poliserna upplevde psykosociala krav som följd av hög arbetsbelastning samtidigt som de upplevde tidspress som resulterade i upplevelsen av kvalitetsbrister, psykisk ohälsa och emotionella krav. Resurserna som kunde underlätta dessa krav var det kollegiala stödet samt krisstöd från polismyndigheten och närvarande yttre befäl. En resurs som saknades var bättre bemanning. Poliserna upplevde att en bättre bemanning skulle kunna motverka en del av påfrestningarna som poliserna erfor i sitt arbete.