Thèses sur le sujet « Energy depletion »

Thesis advisor: Donnah Canavan
Abstract Energy is an emerging concept in social psychology. Baumeister et. al., likening energy to a muscle, have defined exertion of self control as an energy depleting behavior. Energy depletion is measured by reduced performance on a subsequent self-control task. In contrast, Canavan's work on social energy focuses on energy generation and replenishment. Social energy is produced when two or more people are intrinsically interested in the same thing and form a satisfying relationship over this interest. Individuals high in social energy exert more effort, persist longer, and perform better. The present study was conducted in a 2x2 ANOVA design with Social Energy and Depletion as the independent variables and persistence and performance as the dependent variables. Participants worked in groups of two or three groups and were randomly assigned to conditions. In High Social Energy, they imagined managing The Beatles. In the No Social Energy, they imagined managing a cover band playing Beatle's songs. The participants then performed either a depleting or non-depleting proofreading task. Afterwards, the dependent variables were assessed in several tasks: a handgrip task and a measure of creativity and persistence. The results indicate: (1) no significant effect of depletion on the handgrip task and (2) no significant effect of social energy on any of the behavioral measures (i.e. handgrip task or creativity measure). In conclusion, the results did not support either the Depletion or Social Energy behavioral predictions. In the questionnaire data differences between Social Energy and No Social Energy showed significantly higher energy states, social energy, intrinsic motivation, flow, and most important more effort and hard work. The study does improve upon former Social Energy studies in terms of its conceptualization because it successfully manipulated No Social Energy and presented a more sophisticated conceptualization of energy. The manipulations of Social Energy and Depletion interfered with each other making it impossible to test the hypotheses. Paper to be presented at the annual Psychology Honors Conference, Psychology Department, Boston College, Chestnut Hill, Massachusetts, May 2005
Thesis (BS) — Boston College, 2005
Submitted to: Boston College. College of Arts and Sciences
Discipline: Psychology
Discipline: College Honors Program

Traumatic brain injury (TBI) is characterized by a sudden concussive (direct force or shock wave) blow to the head, in which traumatic biomechanical forces are transferred throughout the head and neck. Damage to neural tissue occurs due to rapid acceleration and deceleration forces of the brain, culminating upon impact of the brain with the interior of the skull. At the molecular level, TBI generates a host of physiological responses, which manifest in many different ways. The focus of this thesis will be on the trajectory that progresses through 1) brain acceleration forces, 2) force-induced DNA damage in neurons and glia, 3) activation of DNA repair mechanisms (specifically, poly ADP-ribose polymerase (PARP)), 4) nicotinamide adenine dinucleotide (NAD ⁺) depletion via PARP assembly, 5) the effect of NAD ⁺ depletion on energy metabolism, and 6) the potential value of an NAD⁺ modulator (nicotinamide riboside chloride, NR-Cl) in modulating this effect. Pathologically, reactive oxygen species (ROS) and other free radicals are generated following TBI. The generation of these radicals leads to DNA damage in affected regions of the brain. In response to DNA damage, PARP, a molecule responsible for initiating DNA repair, is activated and begins to polymerize. The assembly of PARP is directly dependent upon nicotinamide adenine dinucleotide (NAD⁺) cannibalization, in which the ADP-ribosyl subunit of NAD⁺ is used to build the large poly ADP-ribose (PAR) polymer. One PAR assembly can consume up to 200 ADP-ribose subunits derived from NAD⁺. This leads to depleted cellular NAD ⁺ and diminished energy metabolism, the severity of which is dependent upon the extent of injury and degree of PARP activation. In this thesis, I will summarize the molecular mechanisms associated with PARP activation, NAD ⁺ depletion, energy dysregulation, and the potential value of NR-Cl as a potential therapeutic agent in mild and moderate TBI.

Research evidence is suggestive of a strength model of self-control, also known as ego depletion, in social psychological literature. Engaging in an initial task of self-control depletes a limited resource, resulting in less self-control on a subsequent, unrelated task. The strength model of self-control has been applied to many practical, everyday situations, such as eating behaviors among dieters. Newer studies suggest that blood glucose is the resource consumed during acts of self-control. Consuming glucose seems to "replete" individuals who have been depleted, improving performance and self-control. The current study aimed to examine the effects of ego-depletion on restrained eaters. The hypothesis was that restrained eaters who were depleted by a task of self-control would exhibit more disinhibition on a taste-test task than would restrained eaters who were not depleted. However, if the participants were given glucose following the depletion task, then their self-control would be "repleted" and they would exhibit similar control to that of the non-depleted participants. Contrary to expectations there were no differences between the groups in terms of total amount of cookies consumed. These results are inconsistent with a glucose model of self-control. Suggestions for future research and implications of the findings are discussed.

Lithium and neodymium are two critical materials in our modern society, many technological solutions depend on them. Lithium is used in batteries, which are used in cars and portable electronics. Neodymium, which is a rare earth element, is mainly used in permanent magnets which are used in smartphones, hard disc drives and turbines. There are many reports regarding the availability of the metals, with different results. The available data on the reserves varies considerably, from the few sources there are. In this report, based on geological availability, forecasts are done to investigate how much the production can increase and when it will peak. The prognoses are based on historic production to which different functions, the logistic, gompertz and richards, are fitted with the least square method. The production will peak in the end of this century and in the beginning of the next century for both metals. The production of lithium does not seem to be sufficient for both producing electric and hybrid cars with only li-ion batteries along with fusion. The neodymium production will be sufficient for producing a lower percentage of direct driven wind turbines and electric cars with NiMH batteries. Lithium in seawater is sometimes considered a future source. Since the lithium concentration is low, large volumes have to be processed in order to extract a reasonable amount of lithium. Currently it is not economic to extract lithium from seawater.

This thesis is submitted as a PhD by Publication. Part A provides an overview of the thesis and summarises its context, research questions, methodological approach and key findings. Part B is a collection of nine, first-named academic papers. The thesis addresses two highly complex and controversial questions within energy policy, namely the nature and magnitude of ‘rebound effects’ from energy efficiency improvements and the extent and rate of depletion of global oil resources. Both of these questions are critically important to the development of a sustainable energy system and both are the subject of long-standing and highly polarised disputes. The thesis adapts, develops and applies a common methodology for reviewing the evidence on these questions, supplements this with original primary research and syntheses the results in a way that improves understanding and provides new insights. The thesis includes four papers examining different aspects of rebound effects and four examining different aspects of global oil depletion. Given the complexity of the chosen topics, the papers cover a wide range of questions, issues and approaches. Collectively the papers: clarify relevant definitional and conceptual issues; evaluate competing methodological and analytical techniques; appraise the methodological quality of empirical studies; identify levels of uncertainty and potential sources of bias; develop simple mathematical models; conduct statistical analyses of primary data; compare and evaluate the results of modelling studies; and synthesise results from multiple research areas to provide novel insights into poorly understood phenomena. A ninth paper evaluates the strengths and limitations of systematic review techniques when applied to complex, policy-relevant questions such as these. The thesis draws two main conclusions. First, rebound effects are frequently large and can substantially reduce the energy and carbon savings achieved from improved energy efficiency. Second, there is a significant risk that the global production of conventional oil will enter sustained decline before 2020. These conclusions run counter to conventional wisdom and have significant implications for public policy. The thesis also shows how the methodology of systematic reviews can be adapted and modified to make a valuable contribution to energy and climate policy research.

In a world struggling to face the disruptive consequences of global warming, developing new energy conversion and storage solutions is of fundamental importance. This PhD thesis focuses on emerging heterostructures based on Indium Tin Oxide nanocrystals (ITO NCs) and two-dimensional Transition Metal Dichalcogenides (2D TMDs) for innovative light-driven optoelectronic nanodevices and energy storage solutions, combining the harvesting, conversion and storage aspects into a unique hybrid nanomaterial. Doped Metal Oxide (MO) NCs are attracting growing interest as nano-supercapacitors due to their ability to store extra charges in their electronic structure with record-high values of capacitance. Remarkably, these materials can be charged with light (i.e., photodoping), a process at the core of this project and so far not understood electronically. Here, the fundamental features involved in the charge accumulation process are investigated and the physics of photodoping explained. Complete control over energetic band bending and depletion layer engineering is demonstrated, exposing the key role of electronically depleted layers in core-shell NCs. Light-induced depletion layer modulation and band bending is the main mechanism responsible for the storage of extra charges in doped MO supercapacitors. Moreover, multi-electron transfer reversible reactions were observed in photodoped NCs when exposed to a frequently used electron acceptor. The coupling between ITO NCs and 2D TMDs allowed the implementation of a novel all-optical localized charge injection scheme for the manipulation of unperturbed 2D materials. Hybrid 0D-2D heterostructures proved all-solid-state photodoping possible, with promising charging dynamics and capacitance values. Theoretical modeling tools were developed, leading to the optimization of the charge storage capacity of 0D NCs. This work is of particular interest for the fabrication of the next-generation of nanostructured light-driven supercapacitors.

The International Energy Agency (IEA) expects total natural gas output in the EU to decrease from 216 billion cubic meters per year (bcm/year) in 2006 to 90 bcm/year in 2030. For the same period, EU demand for natural gas is forecast to increase rapidly. In 2006 demand for natural gas in the EU amounted to 532 bcm/year. By 2030, it is expected to reach 680 bcm/year. As a consequence, the widening gap between EU production and consumption requires a 90% increase of import volumes between 2006 and 2030. The main sources of imported gas for the EU are Russia and Norway. Between them they accounted for 62% of the EU’s gas imports in 2006. The objective of this thesis is to assess the potential future levels of gas supplies to the EU from its two main suppliers, Norway and Russia. Scenarios for future natural gas production potential for Norway and Russia have been modeled utilizing a bottom-up approach, building field-by-field, and individual modeling has been made for giant and semi- giant gas fields. In order to forecast the production profile for an individual giant natural gas field a Giant Gas Field Model (GGF-model) has been developed. The GGF-model has also been applied to production from an aggregate of fields, such as production from small fields and undiscovered resources. Energy security in the EU is heavily dependent on gas supplies from a relatively small number of giant gas fields. In Norway almost all production originates from 18 fields of which 9 can be considered as giant fields. In Russia 36 giant fields account for essentially all gas production. There is limited potential for increased gas exports from Norway to the EU, and all of the scenarios investigated show Norwegian gas production in decline by 2030. Norwegian pipeline gas exports to the EU may even be, by 2030, 20 bcm/year lower than today’s level. The maximum increase in exports of Russian gas supplies to the EU amount to only 45% by 2030. In real numbers this means a mere increase of about 70 bcm In addition, there are a number of potential downside factors for future Russian gas supplies to the European markets. Consequently, a 90% increase of import volumes to the EU by 2030 will be impossible to achieve. From a European energy security perspective the dependence of pipeline gas imports is not the only energy security problem to be in the limelight, the question of physical availability of overall gas supplies deserves serious attention as well. There is a lively discussion regarding the geopolitical implications of European dependence on imported gas from Russia. However, the results of this thesis suggest that when assessing the future gas demand of the EU it would be of equal importance to be concerned about diminishing availability of global gas supplies.

Thesis (PhD)--Stellenbosch University, 2012.
ENGLISH ABSTRACT: Oil is the quintessential resource in the modern industrial economy. It accounts for a third of world primary energy, fuels 95% of global transport systems, sustains a highly mechanised agribusiness and food distribution industry, and provides the feedstock for a staggering array of petrochemical products. Historically, global economic growth has been closely coupled with consumption of energy in general and oil in particular. Yet oil is a finite resource subject to depletion, which has profound implications for the long-term sustainability of industrial civilisation. This dissertation addresses a serious dearth of attention given to this vital subject within South African energy, economic and policy discourses. The overarching aims are to understand the implications of global oil depletion for socioeconomic welfare in South Africa and to propose viable strategies and policies for mitigating and adapting to potential negative impacts. A comparative evaluation of three fields of study found that neoclassical economics is limited by its monistic and reductionist approach and its failure to adequately incorporate energy into its key theoretical models, whereas ecological economics and the socioecological systems approach together provide an appropriate, holistic lens for analysing the role of energy in socioeconomic systems. In this view, energy is the master resource: it is a pre-requisite for economic activity and societal complexity. A review of the literature on global oil depletion finds that a peak and decline in world oil production appears imminent, while world oil exports most likely peaked in 2005. Moreover, the energy return on (energy) investment (EROI) for global oil production is on a declining trend. The world oil peak thus marks the end of the era of cheap and abundant oil. Increasing oil scarcity will likely be reflected in oil prices following a rising trend with heightened volatility. While there are many potential substitutes for oil, all have significant limitations, most have lower EROI than oil, and it may take decades to scale them up sufficiently. Many aspects of the South African socioeconomic system are either directly or indirectly dependent on petroleum fuels, while structural features of the economy and society render them vulnerable to external shocks. Historical evidence and empirical models suggest that oil price and supply shocks will have debilitating socioeconomic impacts. Under business-as-usual policies and behaviours, future oil scarcity will likely lead at best to a gradual contraction in the economy with rising unemployment and inflation, and at worst to systemic collapse of interconnected critical infrastructure systems. A comprehensive range of mitigation measures are proposed, including accelerated investments in renewable energy and electrified mass transport, agro-ecological farming, greening the economy, monetary system reform, and rationing schemes to protect the most vulnerable members of society. Together these measures can build resilience to shocks and gradually decouple economic activity from petroleum consumption. A successful societal transition from a fossil fuel based industrial regime to a sustainable socioeconomic regime requires purposive government intervention, the promotion of sustainability-oriented innovations in technology and institutions, and the political will to surmount obstacles such as powerful vested interests and socio-technical lock-in.
AFRIKAANSE OPSOMMING: Olie is die kern-hulpmiddel in die moderne bedryfsgerigte ekonomie. Dit is verantwoordelik vir ’n derde van die wêreld se primêre energie, verskaf die aandrywing vir 95% van alle vervoerstelsels, onderhou ’n hoogs gemeganiseerde landboubedryf en voedselverspreidingsnywerheid, en voorsien die voerstof vir ’n verstommende reeks petrochemiese produkte. Histories beskou, is globale ekonomiese groei ten nouste gekoppel aan die verbruik van energie oor die algemeen en aan olie in die besonder. Tog is olie ’n beperkte hulpbron wat onderworpe is aan uitputting en lediging, en dit hou gevolglik onmeetlike implikasies vir die algemene langtermyn volhoubaarheid van nywerhede in. Dié verhandeling neem die ernstige gebrek aan aandag binne Suid-Afrikaanse diskoerse oor energie, ekonomie en beleidsrigtings wat betref hierdie lewensbelangrike onderwerp, in oënskou. Die oorkoepelende doelwitte is om die implikasies van globale olie-uitputting op sosio-ekonomiese welvaart in Suid-Afrika te begryp, en om lewensvatbare strategieë en beleidsrigtings voor te stel waarvolgens potensiële negatiewe invloede getemper en by aangepas kan word. ’n Vergelykende evaluering van drie studieterreine het bevind neoklassieke ekonomie is beperk weens sy monistiese en verlagingsbenadering en sy mislukking om energie doelmatig in te sluit by sy sleutel teoretiese modelle, terwyl die benaderings van die ekologiese ekonomie en die sosio-ekologiese stelsels saam ’n toepaslike holistiese lens bied vir die analisering van die rol van energie in sosio-ekonomiese stelsels. In dié opsig is energie die meester-hulpmiddel: dit is ’n voorvereiste vir ekonomiese bedrywigheid en gemeenskapsverbondenheid. ’n Oorsig van die literatuur oor globale olie-lediging toon dat ’n toppunt en daling in wêreldolieproduksie onvermydelik blyk te wees – globale olie-uitvoer het na alle waarskynlikheid sy toppunt in 2005 bereik. Voorts toon die energie-opbrengs op (energie) investering, ofte wel EROI, ten opsigte van wêreldolieproduksie ’n dalende tendens. Die wêreldolie-toppunt dui dus op die einde van die era van goedkoop en oorvloedige olie. Toenemende olieskaarste sal waarskynlik blyk uit oliepryse wat ’n stygende tendens volg gepaard met verskerpte veranderlikheid. Hoewel daar talle potensiële plaasvervangers vir olie bestaan, het almal beduidende beperkinge, die meeste se EROI is laer as olie s’n en dit kan dekades duur alvorens hulle genoegsaam opgegradeer sal kan word. Vele aspekte van die Suid-Afrikaanse sosio-ekonomiese stelsel is of direk of indirek afhanklik van petroleum-brandstowwe, terwyl strukturele kenmerke van die ekonomie en samelewing hulle kwesbaar vir eksterne skokke laat. Lesse uit die verlede en empiriese modelle dui daarop dat die olieprys en skokke rondom die voorsiening daarvan verlammende sosio-ekonomiese impakte en invloede tot gevolg sal hê. Onder ’n sake-soos-gewoonlik-beleid en optrede, sal toekomstige olieskaarste, optimisties beskou, waarskynlik aanleiding gee tot geleidelike inkrimping van die ekonomie met gepaardgaande stygende werkloosheid en inflasie – pessimisties beskou, kan dit die sistematiese ineenstorting van kritiesbelangrike en onderling verbonde infrastruktuurstelsels beteken. ’n Omvattende reeks verligtingsmaatreëls word voorgestel, insluitende versnelde investering in hernubare energie en geëlektrifiseerde massavervoer, agro-ekologiese landbou, vergroening van die ekonomie, monetêre stelselhervorming en rantsoeneringskemas om die mees kwesbare lede van die samelewing te beskerm. Saam kan dié maatreëls veerkragtigheid vestig teen skokke en ekonomiese bedrywigheid geleidelik van petroleumverbruik losmaak. ’n Geslaagde samelewingsoorgang van ’n fossielbrandstof-gebaseerde nywerheidsbestel na ’n volhoubare sosio-ekonomiese bestel vereis doelmatige regeringsintervensie, die bevordering van volhoubaar-georiënteerde innovasies in

Large-scale deployment of low-carbon energy technologies is important for counteracting anthropogenic climate change and achieving universal energy access. This thesis explores potential growth rates of technologies necessary to reach a more sustainable global energy system, the material and energy flows required to commission these technologies, and potential future availability of the required resources. These issues are investigated in five papers. Potential future growth rates of wind energy and solar photovoltaics, and the associated material requirements are explored, taking the expected service life of these technologies into account. Methodology for assessing net energy return and natural resource use for wind energy systems are analyzed. Potential future availability of lithium and phosphate rock are also investigated. Estimates of energy and materials required for technologies such as wind energy and photovoltaics vary, and depend on the assumptions made and methods used. Still, it is clear that commissioning of low-carbon technologies on the scale required to reach and sustain a low-carbon energy system in coming decades requires significant quantities of both bulk materials and scarcer resources. For some technologies, such as thin film solar cells and electric vehicles with lithium-ion batteries, availability of materials could become an issue for potential growth rates. Future phosphate rock production could become highly dependent on few countries, and potential political, social and environmental aspects of this should be investigated in more detail. Material and energy flows should be considered when analyzing growth rates of low-carbon technologies. Their estimated service life can indicate sustainable growth rates of technologies, as well as when materials are available for end-of-life recycling. Resource constrained growth curve models can be used to explore future production of natural resources. A higher disaggregation of these models can enable more detailed analysis of potential constraints. This thesis contributes to the discussion on how to create a more sustainable global energy system, but the methods to assess current and future energy and material flows, and availability of natural resources, should be further developed in the future.

Energy production systems are essential for human progress. They fuel the technologies that underpin economic growth and are prerequisite for efficient food production, education and healthcare. On the flip side, they also incur substantial eco-social costs. Hence, finding and promoting sustainable means of energy production is a key topic within the Environmental Sciences. This thesis examines the sustainability of nuclear power, by comparing its social, economic and ecological impacts to those of wind and solar power. The assessment is performed using Multi-Criteria Analysis (MCA), with a Weighted Sum scoring system and a Distance-To-Target weighting scheme. The selection and the weighting of the indicators are grounded in the Planetary Boundaries framework, the Oxfam Doughnut Economics model and the UN’s Sustainable Development Goals, and the technologies are compared on 9 axes of evaluation; greenhouse gas emissions, land-take requirements, material throughput, non-recyclable wastes, toxic and radioactive wastes, negative health impacts, economic costs, intermittency and energy return on energy invested. The thesis finds nuclear power to be the most sustainable option according to all but three indicators, and in the unified analysis, it outcompetes wind and solar by a factor of 2 and 3 respectively. Also notable is that solar power does not excel in a single impact category; it has the highest greenhouse gas emissions, the largest land-take, and it is costly, intermittent and energy-inefficient. It is also a source of toxic pollution, the effects of which cannot yet be determined. Although wind is more competitive, it consumes vast amounts of physical resources, generates a lot of waste, and its land-take is at least 10 times higher than that of nuclear power. In addition to the MCA, the thesis investigates three perceived threats that are often raised in criticisms of nuclear power; the risk of nuclear fuel depletion, the risk of nuclear weapons proliferation and the risk of catastrophic nuclear accidents. The results show that many popular arguments against the technology are loosely aligned with reality, and the thesis as a whole presents a challenge to the notion that nuclear power is a dangerous and unsustainable energy source.

The formation of modern society has been dominated by coal and oil, and together these two fossil fuels account for nearly two thirds of all primary energy used by mankind.  This makes future production a key question for future social development and this thesis attempts to answer whether it is possible to rely on an assumption of ever increasing production of coal and oil. Both coal and oil are finite resources, created over long time scales by geological processes. It is thus impossible to extract more fossil fuels than geologically available. In other words, there are limits to growth imposed by nature. The concept of depletion and exhaustion of recoverable resources is a fundamental question for the future extraction of coal and oil. Historical experience shows that peaking is a well established phenomenon in production of various natural resources. Coal and oil are no exceptions, and historical data shows that easily exploitable resources are exhausted while more challenging deposits are left for the future. For oil, depletion can also be tied directly to the physical laws governing fluid flows in reservoirs. Understanding and predicting behaviour of individual fields, in particularly giant fields, are essential for understanding future production. Based on comprehensive databases with reserve and production data for hundreds of oilfields, typical patterns were found. Alternatively, depletion can manifest itself indirectly through various mechanisms. This has been studied for coal. Over 60% of the global crude oil production is derived from only around 330 giant oilfields, where many of them are becoming increasingly mature. The annual decline in existing oil production has been determined to be around 6% and it is unrealistic that this will be offset by new field developments, additional discoveries or unconventional oil. This implies that the peak of the oil age is here. For coal a similar picture emerges, where 90% of the global coal production originates from only 6 countries. Some of them, such as the USA show signs of increasing maturity and exhaustion of the recoverable amounts. However, there is a greater uncertainty about the recoverable reserves and coal production may yield a global maximum somewhere between 2030 and 2060. This analysis shows that the global production peaks of both oil and coal can be expected comparatively soon. This has significant consequences for the global energy supply and society, economy and environment. The results of this thesis indicate that these challenges should not be taken lightly.

In this thesis, a Proton Exchange Membrane Fuel Cell is modeled with COMSOL Multiphysics software. A cross-section that is perpendicular to the flow direction is modeled in a 2-D, steady-state, one-phase and isothermal configuration. Anode, cathode and membrane are used as subdomains and serpentine flow channels define the flow field . The flow velocity is defined at the catalyst layers as boundary conditions with respect to the current density that is obtained by using an agglomerate approach at the catalyst layer with the help of fundamental electrochemical equations. Darcy&rsquo
s Law is used for modeling the porous media flow. To investigate the effects of species depletion along the flow channels, a different type of cross-section that is parallel to the flow direction is modeled by adding flow channels as a subdomain to the anode and cathode. Differently, Brinkman Equations are used to define flow in the porous electrodes and the free flow in the channels is modeled with Navier-Stokes equations. By running parallel-to-flow model, mass fractions of species at three different locations (the inlet, the center and the exit of the channel) are predicted for different cell po- tentials. These mass fractions are used as inputs to the perpendicular-to-flow model to obtain performance curves. Finally, by maintaining restricted amount of species by having a very low pressure difference along the channel to represent a single mid-cell of a fuel cell stack, a species depletion problem is detected. If the cell potential is decreased beyond a critical value, this phenomenon causes dead places at which the reaction does not take place. Therefore, at these dead places the current density goes to zero unexpectedly.

Resting energy expenditure (REE) can be reduced in situations of Low Energy Availability (LEA) in athletes, providing both a diagnostic sign of LEA and a potent risk factor for illness, injury and sub-optimal health. Current protocols regarding pre-measurement standardisation for REE are based on non-athlete populations, often following stringent rest and fasting protocols that would not be practical in a high performance environment. Furthermore, the reliability of measurements derived from these protocols has often been assessed in general and clinical populations and is unknown in an athlete population. Characteristics of the test protocol which alter an athlete's presentation (e.g. the location of the test, the duration of recovery from the last exercise bout) and changes in the athlete's own characteristics (changes in intramuscular solute and water content) were identified as variables that could affect the reliability of measurement of REE. This thesis presents a series of distinct but related studies which examine the how these variables affect the measurement and interpretation of REE in athletes. Study 1 examined the effect of testing location on REE in 32 elite and sub-elite athletes. REE was measured either at their bedside upon waking (inpatient) and as an outpatient (laboratory) protocol in a cross-over design following 8 h overnight fasts prior to each measurement. The day to day variation and reliability of each protocol was also assessed. There was no difference in REE when measured under the inpatient or outpatient protocols (7302 ± 1272 and 7216 ± 1119 kJ/d respectively). Both protocols showed good day to day reliability (inpatient 96%, outpatient 97%), however, the outpatient protocol was found to have a greater typical error (TE) (478 kJ/d) and to be less sensitive to changes in REE than the inpatient protocol (336kJ/d). Study 2 was a pilot study that investigated the effect of acute exercise on REE. A cross-over intervention was used in ten male athletes. Measurements were undertaken following training sessions in the morning and afternoon to determine REE approximately 12, 24, 36 and 48 h post exercise. There was a trend for REE to decrease with increasing rest time from exercise, with REE measured 48 h post exercise being significantly lower than REE measured at 12 h. However, the difference of 375 kJ/d was within the typical error determined in Study 1. Study 3 focused on the reliability of DXA estimates of lean mass (LM), which is important in the interpretation of REE relative to fat free mass (FFM). Intramuscular solutes and fluid were manipulated through a series of glycogen depletion, glycogen loading and creatine loading protocols in 18 male cyclists. Main outcome measures were total body and leg LM measured by dual x-ray absorptiometry (DXA), and total body water (TBW) measured by bioelectrical impedance spectroscopy (BIS). Changes in the mean were considered substantial if they reached the threshold for the smallest worthwhile effect of the treatment. There were substantial increases in TBW (2.3 and 2.5%), total body (2.1 and 3.0%) and leg LM (2.6 and 3.1%) following glycogen loading and the combined glycogen-creatine loading protocols respectively. Glycogen depletion caused a substantial decrease in leg LM (- 1.4%) and trivial decrease in total body LM (-1.3%). Creatine loading resulted in substantial increases in TBW and in trivial increases in LM measures. Study 4 addressed the potential development of a practical method to determine an athlete's glycogen stores in combination with DXA-derived estimates of LM by investigating the validity of measuring muscle glycogen via a non-invasive ultrasound technique. The same cohort and design involved in Study 2 was used in this investigation, with the ultrasound derived estimates of muscle glycogen concentration and changes in glycogen concentration being compared with results derived from direct (biopsy-derived) measurements. Poor correlations and substantially large or unclear errors were determined for the ultrasound estimates of muscle glycogen compared to muscle biopsy. Therefore, under the conditions employed in the current study design, the ultrasound technique was unable to accurately predict either single measures of muscle glycogen or changes in muscle glycogen stores. Study 5 applied the findings from Study 3 to investigate how changes in muscle glycogen influence the measurement and interpretation of REE in athletes, with particular interest in its effect on the sensitivity to detect changes in REE over time or as a result of an intervention. The investigation was undertaken within a larger study of the effect of adaptation to a low carbohydrate, high fat (LCHF) diet during a 21 day training camp for endurance athletes. Nineteen elite male race-walkers participated in this study; ten were assigned to the control group (CHO) where they received a diet providing 60% of energy from carbohydrate while nine were in the intervention group in which carbohydrate was restricted to70% of their energy intake for this period. Before and after the dietary interventions, measurements were made of REE, body composition (DXA) and TBW (BIS). Information derived from Study 3 to distinguish acute changes in TBW associated with changes in intramuscular glycogen and its bound water, from true (chronic) changes in muscle mass, was applied to the baseline and post-intervention measures of LM in all athletes. There was a significant decrease in FFM between Baseline and uncorrected Post-Intervention values FFM (-1.4; 95% CI -2.0, -0.80 kg). Using the uncorrected measures of FFM, we interpreted that no change in relative REE between baseline and post intervention occurred in either group. However, when the correction factor was applied to FFM of the LCHF group, correcting for the artefact of reduced muscle glycogen levels associated with restricted carbohydrate intake, we detected a decrease in relative REE post intervention measurements compared to baseline. The conclusions from this series of studies are; 1) Inpatient and outpatient protocols should not be used interchangeably when tracking changes in REE over time. 2) An 8 h overnight fast has good day to day reliability for both inpatient and outpatient protocols. 3) Rest time from exercise should be kept consistent between measures of REE for longitudinal monitoring. 4) Manipulations of muscle glycogen and creatine supplementation cause an artefact in the DXA which changes the estimate of LM accordingly. 5) Measurement of TBW via BIS is better suited to track changes in muscle glycogen than proprietary ultrasound technology. 6) A reduction in muscle glycogen stores, such as that achieved by the consumption of a LCHF diet, creates an artefact in the DXA-derived measurement of FFM, which could potentially alter the interpretation of relative REE. This knowledge should be integrated into best practice guidelines for the measurement of REE in athletes to enhance the reliability and validity of measurement as well as the interpretation of the results.

Attualmente è riscontrabile a livello globale un aumento del numero di giacimenti offshore contenenti un piccolo quantitativo di gas a bassa pressione e dunque destinati ad essere avviati alla procedura finale di chiusura. Per eliminare gli elevati costi di trasporto del gas e valorizzare il sito, nasce il concetto di Gas-to-Wire. Esso consiste nella produzione di elettricità attraverso la combustione del gas naturale in sito. Allo stesso tempo, la consapevolezza che le risorse oil & gas sono destinate ad estinguersi con gli anni ha spinto la comunità scientifica a concentrare l’attenzione su nuove forme di energia rinnovabile, come le onde marine. Nonostante ciò, vi sono ancora delle barriere da abbattere legate sia al prezzo di tali tecnologie che alla produzione di energia in modo discontinuo che rende problematica la loro integrazione nella rete elettrica. Al fine di superare tali problematiche, si è pensato di adottare un sistema ibrido di energia offshore costituito da convertitori di onda e microturbine a gas installate sulla piattaforma presente nel giacimento depleto. Esse forniscono potenza addizionale di bilanciamento sfruttando il concetto di Gas-to-Wire, consentendo una maggiore dispacciabilità dell’energia rinnovabile da onde. Lo scopo del presente lavoro è quello di analizzare le prestazioni energetiche, economiche e d’impatto ambientale del sistema ibrido di energia offshore. Due differenti siti, Mare del Nord e Mar Adriatico, sono stati presi in considerazione al fine di valutare l’influenza delle diverse condizioni meteo-marine, diversi mercati elettrici di dispacciamento e diversi incentivi fiscali per l’integrazione di energia rinnovabile sulle prestazioni del sistema ibrido di energia offshore. Attraverso l’approccio seguito per il dimensionamento e gestione dei due sistemi ibridi, è stato possibile calcolare gli indicatori tecnici, ambientali ed economici.

Diese Arbeit ist ein Beitrag zur Entwicklung einer Strategie für die eine CO2 sparende zu- künftige Landwirtschaft, in der nur geringe Emissionen von Treibhausgasen entstehen, die Stromerzeugung vor Ort aus natürlichen Ressourcen erfolgt, eine maximale Ausnutzung der Sonnenenergie genutzt wird, und der Konflikt zwischen der Nutzung der verfügbaren Ressourcen für Nahrungsmittel und Treibstoff Produktion vermieden wird. Alle Versuche in der Arbeit wurden in den Jahren 2005 -2009 auf der Öko-Farm (TOSOLY) der UTA (Fundación para la Producción Agropecuaria Tropical Sostenible Capitulo Kolumbien - UTA) unter der Leitung von Dr. TR Preston (Präsident ) und MSc Lylian Rodríguez (Director) durchgeführt.
This thesis is a contribution to the strategy that should underpin all future farming systems: namely the need to “de-carbonize” the system, by reducing emissions of greenhouse gases, generating electricity locally from natural resources, making maximum use of solar energy and ensuring there is no conflict between use of available resources for both food and fuel production. All the experiments described in the thesis were carried out in the period 2005 -2009 at the ecological farm (TOSOLY) of the UTA Foundation (Fundación para la Producción Agropecuaria Tropical Sostenible Capitulo Colombia – UTA) of which the principals are Dr T R Preston (President) and MSc Lylian Rodríguez (Director).

This study investigates the use of discretion by oil and gas companies in reporting financial performance and oil and gas reserve estimates during times of high political scrutiny resulting from increases in energy prices. Hypotheses tested in prior literature state that companies facing the risk of increasing taxes or new regulations reduce reported earnings to reduce this risk. This study uses a measure of high profitability (rank order of return on assets relative to industry peers) to identify oil and gas companies more likely to manage earnings during the period from 2002 to 2008. Two measures of discretionary accruals (total and current discretionary accruals), and a measure of discretionary depreciation, depletion, and amortization (DDA) were used as indicators of discretion exercised in reporting earnings. Data on oil and gas reserve disclosures was also hand-collected from Forms 10-K to investigate whether managers use reserve estimate revisions to reduce reported earnings through increasing the annual depletion expense. Results suggest that both oil and gas refining and producing firms use negative discretionary accruals to reduce reported earnings. Results also indicate that profitability is an important determinant of the use of negative discretionary accruals by these companies regardless of the time period examined. There is also evidence that oil and gas producing firms opportunistically revise their oil and gas reserve estimates to increase depreciation, depletion, and amortization expense during periods of high oil prices.

This study endeavors to investigate the negative environmental impacts of the prevailing ICT design approaches and to explore some potential remedies for ICT design unsustainability from environmental and corporate sustainability perspectives. More specifically, it aims to spotlight key environmental issues related to ICT design, including resource depletion; GHG emissions resulting from energy-intensive consumption; toxic waste disposal; and hazardous chemicals use; and also to shed light on how alternative design solutions can be devised based on environmental sustainability principles to achieve the goals of sustainable technologies. The study highlights the relationship between ICT design and sustainability and how they can symbiotically affect one another. To achieve the aim of this study, an examination was performed through an extensive literature review covering empirical, theoretical, and critical scholarship. The study draws on a variety of sources to survey the negative environmental impacts of the current mainstream ICT design approach and review the potential remedies for unsustainability of ICT design. For theory, central themes were selected for review given the synergy and integration between them as to the topic under investigation. They include: design issues; design science; design research framework for ICT; sustainability; corporate sustainability; and design and sustainability. Findings highlight the unsustainability of the current mainstream ICT design approach. Key environmental issues for consideration include: resource depletion through extracting huge amounts of material and scarce elements; energy-intensive consumption and GHG emissions, especially from ICT use phase; toxic waste disposal; and hazardous substances use. Potential remedies for ICT design unsustainability include dematerialization as an effective strategy to minimize resources depletion, de-carbonization to cut energy consumption through using efficient energy required over life cycle and renewable energy; recyclability through design with life cycle thinking (LCT) and extending ICT equipment’s operational life through reuse; mitigating hazardous chemicals through green design - low or non-noxious/less hazardous products. As to solving data center dilemma, design solutions vary from hardware and software to technological improvements and adjustments. Furthermore, corporate sustainability can be a strategic model for ICT sector to respond to environmental issues, including those associated with unsustainable ICT design. In the same vein, through adopting corporate sustainability, ICT-enabled organizations can rationalize energy usage to reduce GHG emissions, and thereby alleviating global warming. This study provides a novel approach to sustainable ICT design, highlighting unsustainability of its current mainstream practices. Review of the literature makes an advance on extant reviews of the literature by highlighting the symbiotic relationship between ICT design and environmental sustainability from both research and practice perspectives. This study adds to the body of knowledge and previous endeavours in research of ICT and sustainability. Overall, it endeavours to present contributions and avenues for further theoretical and empirical research and development.
+46704352135/+212662815009

碩士
高苑科技大學
土木工程研究所
98
After the 921 Earthquake in Taiwan, it is easy to cause landslides debris flows in the mountain whenever there is heavy rain or typhoon. Moreover, in recent years, the influences of increasing equatorial temperature and abnormal weather cause super heavy rain with precipitation almost equal to the annual rainfall in Taiwan. Due to lots of rain flowing into the river channels, river bed and cross-strait erosion are aggravated, which trigger the avalanche of debris and then bring about debris flow and severe disaster. As mentioned in the paper regarding to step pools on the topography, step - pool has the capability to dissipate energy and stabilize the river bed. Zhao-Yin (2003) reported that step - pool terrain has been fully developed since river bed experienced flow force for several years in the steep mountain rivers. This step - pool structure can magnify the resistance of river flow and consume the energy of river flow, so that the river bed would be protected from erosion. Even though step – pool terrain could be found in mountain rivers of Taiwan from time to time, in this study, the ability of step-pool terrain to decrease flow strength would be understood through on-site measurements and simulation for the potential debris flow hazard torrent occurred in step pool terrain.

Alcuni degli sport più impegnativi dal punto di vista fisico sono quelli che richiedono un impegno prolungato ad alta intensità. Ne consegue il ricorso, per tali esercizi, ad entrambi i sistemi energetici, aerobico e anaerobico, e la possibilità per l’organismo di sostenerli solo per alcuni minuti. Una migliore conoscenza dei meccanismi alla base della fatica e le sue limitazioni garantirebbe maggiore comprensione di come ritardare l’insorgenza della fatica. Ciò sarà rilevante sia per atleti alla ricerca del miglioramento delle loro prestazioni, che per anziani e pazienti con malattie croniche la cui attività quotidiana risulti limitata. Nonostante varie teorie sullo sviluppo della fatica e “task failure” siano presenti in letteratura, non esiste consenso sui precisi meccanismi alla loro base. Pertanto, l’obiettivo principale di questa tesi è stato quello di studiare l’esercizio ad alta intensità, con un approccio multi-disciplinare per ottenere una migliore comprensione dei differenti processi che determinano l’esaurimento. In primo luogo, tale fenomeno è stata valutato dal punto di vista energetico, modello che imputa l’esaurimento alla deplezione delle riserve di energia anaerobica. A tal fine, ai partecipanti è stato chiesto di pedalare su un cicloergometro con intensità sovramassimale fino all’esaurimento, dopo di che la potenza veniva ridotta a un livello inferiore, ma comunque sovramassimale. Secondo il modello di esaurimento dell’energia, i soggetti sperimentali non avrebbero dovuto essere in grado di continuare a pedalare. Tuttavia, i risultati hanno mostrato che i partecipanti hanno continuato l’esercizio per un consistente lasso di tempo a questo carico di lavoro ad alta intensità. Si è pertanto concluso, che l’esaurimento dell’energia anaerobica non avrebbe potuto essere la causa diretta dell’interruzione dell’attività. L’elaborazione dei risultati ha inoltre messo in evidenza come i comuni metodi per quantificare la produzione anaerobica di energia, il modello della potenza critica e il metodo del massimo debito di ossigeno, potrebbero non essere accurati. L’obiettivo del secondo studio era di valutare il potenziale coinvolgimento dei processi mentali inconsci durante l’esercizio ad alta intensità, e di confutare l’ipotesi secondo la quale l’esaurimento dipenda esclusivamente da fattori periferici. Questo è stato ottenuto attraverso la manipolazione del tempo visualizzato da un orologio durante l’esercizio ad alta intensità fino all’esaurimento. È interessante notare come i partecipanti abbiano pedalato per un tempo significativamente più lungo con l’orologio che correva veloce (x 1.1) rispetto a quello lento (x 0,9). Da questi risultati, si è concluso che i processi inconsci centrali sono coinvolti nella regolazione dei processi che determinano l’interruzione dell’esercizio. Ulteriori misure inerenti pattern di attivazione di quattro muscoli della parte inferiore della gamba (con elettromiografia) ha evidenziato una piccola differenza nella strategia di reclutamento tra le due condizioni veloce e lenta dell’orologio, il che potrebbe spiegare come i partecipanti abbiano prolungato la durata del loro esercizio. Nello studio finale, i partecipanti hanno effettuato con una sola gamba ripetuti esercizi di estensione dinamica del ginocchio. Una tecnica di interpolazione è stata utilizzata per monitorare il contributo dei fattori centrali e periferici di fatica muscolare durante l’esercizio fisico ad alta intensità. I risultati hanno rivelato che stanchezza centrale viene sviluppata durante la ripetizione di esercizi ad alta intensità. Tuttavia, poiché non è stata osservata nessuna riduzione significativa nell’attivazione volontaria dopo la prima serie di esercizi, la fatica centrale non è stata ritenuta il prerequisito per l’esaurimento. Inoltre, si crede che l’esaurimento sia il risultato di una riduzione critica della forza muscolare massima. Tuttavia, le variazioni inter-individuali della massima forza volontaria in seguito all’esaurimento, hanno suggerito che non solo la fatica periferica, ma che una combinazione di diversi fattori, determini l’esaurimento durante l’esercizio fisico ad alta intensità. Sulla base dei risultati degli studi presentati in questa tesi, si può concludere che la fatica muscolare dipenda da componenti centrali e periferiche, ma anche che processi mentali (subconscio) contribuiscano all’esaurimento durante l’esercizio fisico ad alta intensità. Si propone che durante l’esercizio l’integrazione di tali processi porti ad un aumento della percezione dello sforzo, che si traduce nell’interruzione volontaria dell’esercizio nel momento in cui è stato raggiunto il livello massimo tollerabile. In definitiva, un modello è proposto con l’obiettivo di unificare le teorie esistenti e fornire una panoramica dei fattori potenzialmente limitanti e i meccanismi che portano all’esaurimento durante l’esercizio fisico ad alta intensità.
Some of the most physically-demanding sports are those that require prolonged high-intensity exercise. Such tasks place high demands on both the aerobic and anaerobic energy systems, and can only be sustained for several minutes. A better understanding of the underlying mechanisms of fatigue and its limitations would provide greater insight into how to delay the onset of fatigue. This will be relevant for athletes trying to improve their performance, but also for the elderly and patients with chronic diseases whose daily-life activities are limited. Although various theories about the development of fatigue and task failure have been described in the literature, no consensus exists of the precise mechanisms underlying fatigue and task failure. Therefore, the main objective of this thesis was to study high-intensity exercise, using a multi-disciplinary approach to gain a better understanding of the differences processes determining task failure. Firstly, the energy-depletion model was evaluated, which states that task failure coincides with the depletion of a finite store of anaerobic energy. To this end, participants exercised on a cycle ergometer at a supra-maximal intensity until task failure, after which the power output was dropped to a lower, but still supra-maximal level. According to the energy depletion model, participants should not be able to continue cycling. However, the results showed that the participants continued cycling for a substantial time at this high-intensity workload. It was therefore concluded that anaerobic energy depletion could not have been the direct cause of task failure. The results subsequent calculations also indicated that the common methods to quantify anaerobic energy production, the critical power model and the maximal accumulated oxygen deficit method, might not be accurate. The purpose of the second study was to evaluate the potential involvement of subconscious mental processes during high-intensity cycling exercise, and to challenge the assumption that peripheral factors exclusively cause task failure. This was achieved by manipulation of perceived time by a displayed clock during high-intensity cycling exercise to task failure. Interestingly, participants cycled for a significantly longer time while watching a fast-running clock (x 1.1) compared to a slow (x 0.9) clock. From these results, it was concluded that central subconscious processes are involved in the regulation of task failure. Additional measurements of the activation patterns of four muscles in the lower leg (using electromyography) revealed a small difference in the recruitment strategy between the fast and slow clock condition, which might explain how participants prolonged their exercise duration. In the final study, participants performed repeated bouts of dynamic one-legged knee-extension exercise. A twitch-interpolation technique was used to monitor the contribution of central and peripheral factors to muscle fatigue during high-intensity exercise. The results revealed that central fatigue developed during the repeated bouts of high-intensity exercise. However, as no significant reduction in voluntary activation was observed after the first exercise bouts, central was not a prerequisite for task failure. Furthermore, task failure is thought to occur as a result of a critical reduction of maximal muscle force. However, inter-individual variations in maximal voluntary force after task failure suggested that not solely peripheral fatigue, but that a combination of different factors determines the moment of task failure during high-intensity exercise. Based on the results of the studies presented in this thesis, it can be concluded that muscle fatigue with central and peripheral components, but also (subconscious) mental processes contribute to task failure during high-intensity exercise. It is proposed that during exercise the integration of these fatiguing processes lead to an increase in the perception of effort, ultimately resulting in volitional task failure at the moment the maximal tolerable level has been reached. Ultimately, a model is proposed aiming to unify existing theories and provide an overview of the potentially limiting factors and mechanisms leading to task failure during high-intensity exercise.

abstract: There was a growing trend in the automotive market on the adoption of Hybrid Electric Vehicles (HEVs) for consumers to purchase. This was partially due to external pressures such as the effects of global warming, cost of petroleum, governmental regulations, and popularity of the vehicle type. HEV technology relied on a variety of factors which included the powertrain (PT) of the system, external driving conditions, and the type of driving pattern being driven. The core foundation for HEVs depended heavily on the battery pack and chemistry being adopted for the vehicle performance and operations. This paper focused on the effects of hot and arid temperatures on the performance of LiFePO4 (LFP) battery packs and presented a possible modeling method for overall performance. Lithium-ion battery (LIB) packs were subjected to room and high temperature settings while being cycled under a current profile created from a drive cycle. The Federal Urban Driving Schedule (FUDS) was selected and modified to simulate normal city driving situation using an electric only drive mode. Capacity and impedance fade of the LIB packs were monitored over the lifetime of the pack to determine the overall performance through the variables of energy and power fade. Regression analysis was done on the energy and power fade of the LIB pack to determine the duration life of LIB packs for HEV applications. This was done by comparing energy and power fade with the average lifetime mileage of a vehicle. The collected capacity and impedance data was used to create an electrical equivalent model (EEM). The model was produced through the process of a modified Randles circuit and the creation of the inverse constant phase element (ICPE). Results indicated the model had a potential for high fidelity as long as a sufficient amount of data was gathered. X-ray powder diffraction (XRD) and a scanning electron microscope (SEM) was performed on a fresh and cycled LFP battery. SEM results suggested a dramatic growth on LFP crystals with a reduction in carbon coating after cycling. XRD effects showed a slight uniformed strain and decrease in size of LFP olivine crystals after cycling.
Dissertation/Thesis
Masters Thesis Engineering 2016