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Bachelor thesis. / Format: PDF. Bibl.

Sweden has gone from an agricultural society to an industrial society which may lead to a less self-sufficient country. The concept of self-sufficiency has been a way to narrate how dependent a country is of the import to provide the population with enough food. The Swedish society is not only dependent of import of food but also import of fuel, chemical fertilizers, seeds and spare parts to various agricultural machineries. This study will investigate how agricultural area and enterprises and energy supply per person in Sweden have changed during 1970 to 2020. The results show an overall decrease of agricultural land with 16 percent and especially a decrease is found among smaller scale agricultural enterprises. In contradiction an increase is seen of large agricultural companies with 200 percent during this time period. The energy supply per person has decreased and after taking export into account the change is from 114 percent self -sufficiency 1970 to a 48 percent self-sufficiency during 2020. In conclusion; reduced arable land, decreasing agricultural enterprises and a lower degree of self-sufficiency makes Sweden more dependent on commercial agreements and more vulnerable for trade restrictions. Trade restrictions regarding goods to the agriculture industry could lead to food shortage in the country.

Citrus black spot (CBS), caused by Guignardia citricarpa Kiely, occurs in various citrus producing regions of the world. Due to the potential phytosanitary risk associated with the export of fruit from CBS positive production areas to CBS-free countries, restrictive trade barriers have been introduced. This study aimed to further elucidate some epidemiological aspects of CBS that can be used to address critical questions identified in the pest risk assessment submitted by South Africa to the World Trade Organisation to address phytosanitary trade restrictions. Results indicated that Eureka lemon leaf litter exposed to viable pycnidiospores under controlled conditions or in the field in different production regions of South Africa, were not infected and colonised by G. citricarpa. Symptomatic CBS fruit or peel lying on the ground underneath citrus trees therefore can not lead to infection and colonisation of freshly detached leaves or leaf litter, or represent a source of inoculum in citrus orchards. Symptomatic fruit therefore pose no danger for the establishment of the pathogen in CBS-free orchards and are not considered to be a pathway for the pathogen. The period of leaf susceptibility to G. citricarpa was indicated to be maximum eight and ten months from development, for Valencia orange and Eureka lemon, respectively, in a greenhouse study. The susceptibility period of citrus leaves to infection by the black spot pathogen could be longer than previously perceived. Ascospores were captured, using the newly developed Kotzé Inoculum Monitor (KIM), from natural Valencia orange and Eureka lemon leaf litter during October to March with peak ascospore availability between December to February. The KIM is the first sampler designed to capture fungal spores directly from plant material in the laboratory without environmental influences and was effectively used to confirm that ascospores production is seasonal. The KIM in combination with environmental data can be used to improve control through more targeted fungicide applications. Techniques such as isolations and DNA amplification with species-specific primers to detect the pathogen directly from symptomless green leaves have a low success rate due to the restricted growth of the pathogen in latently infected tissue. Artificial leaf wilting enhanced the detection of G. citricarpa from symptomless leaves. Leaf wilting is a reliable, fast and effective method to detect the CBS pathogen and can be applied to monitor citrus nurseries and orchards throughout the year. It can also be applied to monitor pest-free orchards to maintain its CBS pest-free status. This study confirmed that sanitation practices, such as leaf litter removal and mulching of leaf litter with wheat straw can decrease the primary inoculum, ascospores, of CBS and contribute to better management of the disease in a commercial orchard. Regardless of the prevailing climatic conditions each year, control achieved through leaf litter management resulted in >95% clean fruit and are equal to the control achieved with industry standard fungicides. This approach provided improved integrated disease control and an alternative to chemical control. / Thesis (PhD)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted

This thesis examines the potential effects of a price cap sanction on semi-finished steel products against the Russian steel industry. The research question is: "What are the effects on the Russian economy of a price cap on semi-finished steel products?”. By constructing a theoretical model and applying empirically-based parameters, estimation of the sanction's effects on Russia and the world is possible. The findings suggest that a severe price cap, such as capping Russian steel prices at 72 $/tonne (90 % of original price), only results in a 2,7 % decrease in supplied quantity but causes a significant loss of profit (approximately 10 billion dollars annually). In the long-run, market rebalancing somewhat diminishes these losses. An alternative model however indicates that Russian exporters would cease exports at a minimum price of 502,5 $/tonne, leading to a dramatic increase in global prices. Therefore, a recommended price cap of 30 % or less of the current market price is advised – leading to 3,4 billion dollars in annual Russian losses. This study contributes to the understanding of sanctions as an economic tool and informs the ongoing debate on the efficacy of price cap sanctions against a sizable economy like Russia's and on inelastic products such as semi-steel.

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We develop and evaluate two significant modeling concepts within the context of a large-scale Airspace Planning and Collaborative Decision-Making Model (APCDM) and, thereby, enhance its current functionality in support of both strategic and tactical level flight assessments. The first major concept is a new severe weather-modeling paradigm that can be used to assess existing tactical en route flight plan strategies such as the Flight Management System (FMS) as well as to provide rerouting strategies. The second major concept concerns modeling the mediated bartering of slot exchanges involving airline trade offers for arrival/departure slots at an arrival airport that is affected by the Ground Delay Program (GDP), while simultaneously considering issues related to sector workloads, airspace conflicts, as well as overall equity concerns among the airlines. This research effort is part of an $11.5B, 10-year, Federal Aviation Administration (FAA)-sponsored program to increase the U.S. National Airspace (NAS) capacity by 30 percent by the year 2010. Our innovative contributions of this research with respect to the severe weather rerouting include (a) the concept of "Probability-Nets" and the development of discretized representations of various weather phenomena that affect aviation operations; (b) the integration of readily accessible severe weather probabilities from existing weather forecast data provided by the National Weather Service (NWS); (c) the generation of flight plans that circumvent severe weather phenomena with specified probability levels, and (d) a probabilistic delay assessment methodology for evaluating planned flight routes that might encounter potentially disruptive weather along its trajectory. Given a fixed set of reporting stations from the CONUS Model Output Statistics (MOS), we begin by constructing weather-specific probability-nets that are dynamic with respect to time and space. Essential to the construction of the probability-nets are the point-by-point forecast probabilities associated with MOS reporting sites throughout the United States. Connections between the MOS reporting sites form the strands within the probability-nets, and are constructed based upon a user-defined adjacency threshold, which is defined as the maximum allowable great circle distance between any such pair of sites. When a flight plan traverses through a probability-net, we extract probability data corresponding to the points where the flight plan and the probability-net strand(s) intersect. The ability to quickly extract this trajectory-related probability data is critical to our weather-based rerouting concepts and the derived expected delay and related cost computations in support of the decision-making process. Next, we consider the superimposition of a flight-trajectory-grid network upon the probability-nets. Using the U.S. Navigational Aids (Navaids) as the network nodes, we develop an approach to generate flight plans that can circumvent severe weather phenomena with specified probability levels based on determining restricted, time-dependent shortest paths between the origin and destination airports. By generating alternative flight plans pertaining to specified threshold strand probabilities, we prescribe a methodology for computing appropriate expected weather delays and related disruption factors for inclusion within the APCDM model. We conclude our severe weather-modeling research by conducting an economic benefit analysis using a k-means clustering mechanism in concert with our delay assessment methodology in order to evaluate delay costs and system disruptions associated with variations in probability-net refinement-based information. As a flight passes through the probability-net(s), we can generate a probability-footprint that acts as a record of the strand intersections and the associated probabilities from origin to destination. A flight plan's probability-footprint will differ for each level of data refinement, from whence we construct route-dependent scenarios and, subsequently, compute expected weather delay costs for each scenario for comparative purposes. Our second major contribution is the development of a novel slot-exchange modeling concept within the APCDM model that incorporates various practical issues pertaining to the Ground Delay Program (GDP), a principal feature in the FAA's adoption of the Collaborative Decision-Making (CDM) paradigm. The key ideas introduced here include innovative model formulations and several new equity concepts that examine the impact of "at-least, at-most" trade offers on the entire mix of resulting flight plans from respective origins to destinations, while focusing on achieving defined measures of "fairness" with respect to the selected slot exchanges. The idea is to permit airlines to barter assigned slots at airports affected by the Ground Delay Program to their mutual advantage, with the FAA acting as a mediator, while being cognizant of the overall effect of the resulting mix of flight plans on air traffic control sector workloads, collision risk and safety, and equity considerations. We start by developing two separate slot-exchange approaches. The first consists of an external approach in which we formulate a model for generating a set of package-deals, where each package-deal represents a potential slot-exchange solution. These package-deals are then embedded within the APCDM model. We further tighten the model representation using maximal clique cover-based cuts that relate to the joint compatibility among the individual package-deals. The second approach significantly improves the overall model efficiency by automatically generating package-deals as required within the APCDM model itself. The model output prescribes a set of equitable flight plans based on admissible trades and exchanges of assigned slots, which are in addition conformant with sector workload capabilities and conflict risk restrictions. The net reduction in passenger-minutes of delay for each airline is the primary metric used to assess and compare model solutions. Appropriate constraints are included in the model to ensure that the generated slot exchanges induce nonnegative values of this realized net reduction for each airline. In keeping with the spirit of the FAA's CDM initiative, we next propose four alternative equity methods that are predicated on different specified performance ratios and related efficiency functions. These four methods respectively address equity with respect to slot-exchange-related measures such as total average delay, net delay savings, proportion of acceptable moves, and suitable value function realizations. For our computational experiments, we constructed several scenarios using real data obtained from the FAA based on the Enhanced Traffic Management System (ETMS) flight information pertaining to the Miami and Jacksonville Air Route Traffic Control Centers (ARTCC). Through our experimentation, we provide insights into the effect of the different proposed modeling concepts and study the sensitivity with respect to certain key parameters. In particular, we compare the alternative proposed equity formulations by evaluating their corresponding slot-exchange solutions with respect to the net reduction in passenger-minutes of delay for each airline. Additionally, we evaluate and compare the computational-effort performance, under both time limits and optimality thresholds, for each equity method in order to assess the efficiency of the model. The four slot-exchange-based equity formulations, in conjunction with the internal slot-exchange mechanisms, demonstrate significant net savings in computational effort ranging from 25% to 86% over the original APCDM model equity formulation. The model has been implemented using Microsoft Visual C++ and evaluated using a C++ interface with CPLEX 9.0. The overall results indicate that the proposed modeling concepts offer viable tools that can be used by the FAA in a timely fashion for both tactical purposes, as well as for exploring various strategic issues such as air traffic control policy evaluations; dynamic airspace resectorization strategies as a function of severe weather probabilities; and flight plan generation in response to various disruption scenarios. / Ph. D.

Sverige och Europa genomgår en omställning till högre andel förnybar el, samtidigt har Europas elpriser varit rekordhöga de senaste åren och den sammankopplade elhandeln i EU har bidragit till höga elpriser i Sverige. Litteraturstudien har avsett att redogöra för hur strategier som begränsar elhandeln mellan Sverige och EU påverkar Sveriges försörjningstrygghet, elpriser och konkurrenskraft samt hur miljön påverkas av dessa strategier. Studien kartlägger elhandeln i Sverige och Europa, både den fysiska och marknadsmässiga samt de legala faktorer som påverkar den. Balansen mellan försörjningstrygghet, miljö, ekonomiska faktorer och internationell elhandel undersöks. Dessutom introduceras några strategier för att begränsa och kontrollera den internationella elhandeln, de främsta var fysisk begränsning av elöverföringen samt olika prissättningsstrategier. Resultaten visar att en fysisk begränsning av gränsöverskridande elhandel inte är möjlig givet de regelverk som finns på plats men skulle drabba försörjningstryggheten samt medföra osäkerheter på lång sikt i ekonomiska faktorer som konkurrenskraft och elpriser i Sverige. Dessutom skulle en fysisk begränsning försvåra övergången till mer förnybar energi i Sverige och Europa och på så vis påverka miljön negativt. Det framstår därför som mer gynnsamt på kort sikt att istället kontrollera elhandeln med olika prissättningsstrategier såsom lägre priser för inhemska konsumenter, för att på så sätt dra nytta av inkomsterna och miljönyttan som internationell elhandel innebär utan att de nationella elpriserna drabbas i samma utsträckning. Beroende på prissättningsstrategi innebär det att den negativa påverkan på antingen hushållens eller industriernas elpriser reduceras, varav framför allt det senare innebär att konkurrenskraften inte påverkas lika negativt. Dock visar studien att en sådan modell kräver ytterligare forskning för att utvärdera dess genomförbarhet och potentiella effekter. Slutsatsen av studien indikerar att både bibehålla den nuvarande situationen och implementera alternativa strategier medför olika för- och nackdelar avseende försörjningstrygghet, elpriser, den svenska industrins konkurrenskraft och miljöpåverkan. För att identifiera den mest optimala strategin krävs ytterligare forskning samt en noggrann avvägning av de potentiella konsekvenserna. / Sweden and Europe are increasingly shifting towards renewable electricity. However, Europe has recently seen record-high electricity prices, with the interconnected electricity trade within EU contributing to high prices in Sweden. This literature review aims to elucidate the impacts of strategies restricting electricity trade between Sweden and the EU on Sweden’s energy security, electricity prices, competitiveness, and the environment. The study maps the physical and market dynamics of electricity trade in Sweden and Europe and examines the legal factors influencing it. It also explores the balance between energy security, environmental considerations, economic factors, and international electricity trade. Various strategies for limiting and controlling international electricity trade are introduced, focusing on physical restrictions on electricity transmission and different pricing strategies. The findings suggest that physically restricting cross-border electricity trade is not feasible under current regulations and would harm energy security, leading to long-term uncertainties in economic factors such as competitiveness and electricity prices in Sweden. Additionally, such restrictions would impede the transition to renewable energy in Sweden and Europe, adversely affecting the environment. Therefore, controlling electricity trade through various pricing strategies, such as lower prices for domestic consumers, seems more advantageous in the short run. This approach allows for leveraging the economic and environmental benefits of international electricity trade without significantly impacting national electricity prices. Depending on the pricing strategy, the negative impact on either household or industrial electricity prices is mitigated, with the latter primarily ensuring competitiveness remains less affected. However, further research is needed to evaluate the feasibility and potential effects of this model. The study concludes that both maintaining the current situation and implementing alternative strategies entail various advantages and disadvantages concerning energy security, electricity prices, the competitiveness of Swedish industry, and environmental impact. To identify the most optimal strategy, further research and a careful assessment of the potential consequences are required.