Dissertations / Theses on the topic 'Harvesting methods'
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JANA, SOURAV KANTI. "Light harvesting methods in photovoltaic devices with superficial treatments." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28621.
Full textCerney, Dawna Lynn. "Two methods of harvesting native grass community seed." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0015/MQ48244.pdf.
Full textBlanchard, Jonathan Peter. "Rainwater Harvesting Storage Methods and Self Supply in Uganda." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/3979.
Full textLenhard, Allison N. "Review of energy harvesting methods for twin screw extruders." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127922.
Full textCataloged from the official PDF of thesis.
Includes bibliographical references (pages 44-48).
Energy harvesting is the process of accumulating and storing energy from residual sources for use in powering electronic devices. Low-power energy harvesting technologies typically utilize either mechanical, thermal, radiation, flow-based, or bio-chemical energy sources. Research in low-power energy harvesting technologies is motivated by an increased interest in the Internet of Things and the need to create isolated electronic systems, such as wireless sensor networks for system monitoring. Twin screw extruders are a type of extrusion processing machinery and could benefit from a condition monitoring system. Implementing a condition monitoring system for a twin screw extruder can prevent wasting materials, producing unusable products, and working extensively on machine maintenance. However, it becomes difficult to integrate a condition monitoring system into the machinery because of the lack of accessibility. Condition monitoring would have to occur in the process section of the twin screw extruder, but the nature of the process section makes it difficult to implement a traditionally wired and powered condition monitoring system. A condition monitoring system powered by energy harvesting techniques would be ideal for a twin screw extruder. The shaft mechanical vibrations, high temperature thermal dissipation, and polymer fluid dynamics present in a twin screw extruder can potentially be used in an energy harvesting system. After a literature review, mechanical vibrations and temperature gradients were regarded as the best potential energy harvesting drivers. Based on preliminary analysis of the system, vibrational energy harvesting is predicted to produce between 3.35-16.75 mW of power, while thermally driven energy harvesting is expected to produce between 8-15 mW of power. The estimated power output would be significant enough to power a low-power consumption strain sensor and has the potential to power other sensors as well.
by Allison N. Lenhard.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
Grozdanovski, Tatjana, and Tatjana grozdanovski@rmit edu au. "Multi-scaling methods applied to population models." RMIT University. Mathematical and Geospatial Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091130.102832.
Full textEriksson, Jesper, and Shwana Piroti. "Review of Methods for Energy Harvesting from a Vehicle Suspension System." Thesis, KTH, Skolan för teknikvetenskap (SCI), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-223215.
Full textThiffault, Évelyne. "Biogeochemistry of forest harvesting methods in the boreal zone of Quebec." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/24124/24124.pdf.
Full textSingh, Raymond Charan. "Modeling Energy Harvesting From Membrane Vibrations using Multi-physics Modeling." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/76793.
Full textMaster of Science
Wang, Yafang [Verfasser], and Gerhard [Akademischer Betreuer] Weikum. "Methods and tools for temporal knowledge harvesting / Yafang Wang. Betreuer: Gerhard Weikum." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2013. http://d-nb.info/1052779883/34.
Full textGriffin, S. Michael. "Islet tissue autotransplantation - harvesting methods and long-term assessment of graft function." Thesis, University of Newcastle Upon Tyne, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329157.
Full textReed, Ryan Tyler. "Wireless Information and Power Transfer Methods for IoT Applications." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/104146.
Full textMaster of Science
Future devices are expected to feature high levels of interconnectivity and have long lifetimes. RF energy from dedicated power beacons or ambient sources, such as Wi-Fi, cellular, DTV, or radio stations can be used to power these devices allowing them to be battery-less. These devices that harvest the RF energy can use that energy to transmit information. This thesis develops various methods to harvest RF energy and use this energy to transmit information as efficiently as possible. The designs are verified through simulation and experimental results.
Bell, Robert D. "Influences of varying stand harvest methods on timber harvesting costs in southwestern Virginia hardwoods." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43079.
Full textMaster of Science
Björk, Gabriella. "Evaluation of system design strategies and supervised classification methods for fruit recognition in harvesting robots." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217859.
Full textDet här masterexamensarbetet har utförts av en student från Kungliga Tekniska Högskolan i samarbete med Cybercom Group. Målet var att utvärdera och jämföra designstrategier för igenkänning av frukt i en skörderobot och prestandan av klassificerande maskininlärningsalgoritmer när de appliceras på det specifika problemet. Arbetet omfattar grunderna av dessa system; till vilket parametrar, begränsningar, krav och designbeslut har undersökts. Ramverket användes sedan som grund för implementationen av sensorsystemet, processerings- och klassifikationsalgoritmerna. En tomatplanta i pplast med frukter av varierande mognasgrad användes som bas för träning och validering av systemet, och en Kinect för Windows v2 utrustad med sensorer för högupplöst färg, djup, och infraröd data anvöndes för att erhålla bilder. Datan processerades i MATLAB med hjälp av mjukvaruutvecklingskit för Kinect tillhandahållandet av Windows, i syfte att extrahera egenskaper ifrån objekt på bilderna. Multipla vyer erhölls genom att låta tomatplantan rotera på en plattform, driven av en stegmotor Arduino Uno. De binära klassifikationsalgoritmer som testades var Support Vector MAchine, Decision Tree och k-Nearest Neighbor. Modellerna tränades och valideras med hjälp av en five fold cross validation i MATLABs Classification Learner applikation. Prestationsindikatorer som precision, återkallelse och F1- poäng beräknades för de olika modellerna. Resultatet visade bland annat att statiska modeller som k-NN och SVM presterade bättre för det givna problemet, och att den sistnömnda är mest lovande för framtida applikationer.
Hodges, Amelia Lynn. "Investigation of antennas and energy harvesting methods for use with a UHF microtransceiver in a biosensor network." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/16218.
Full textDepartment of Electrical and Computer Engineering
William B. Kuhn
This work was a part of NASA EPSCoR Project NNX11AM05A: Biosensor Networks and Telecommunication Subsystems for Long Duration Missions, EVA Suits, and Robotic Precursor Scout Missions. The project’s main goal is the development of a wireless sensor network inside an astronaut’s spacesuit. Antennas are essential components in a wireless network. Since this antenna will be used inside the spacesuit it is important to consider both the physical size limitations and the desired antenna polarization. After exploring the WWVB radio station antenna which provides the preferred vertical polarization and has a suitable aspect ratio, the top hat antenna seemed promising for intrasuit communication. The design of a top hat antenna is outlined. Then, the antennas were tested using 433 MHz radios in a full scale model spacesuit. This spacesuit was designed specifically to model the behavior of aluminized mylar in the real suit. Test results support the feasibility of an intrasuit wireless network. If a gateway radio is placed on the chest or back, a sensor could be placed anywhere on the body and provide an adequate signal. These initial tests did not include a matching network, but the additional link-margin afforded by a matching network, even an imperfect match, is considered. Energy harvesting is explored as an alternative to batteries powering the intrasuit radio. In the oxygen rich environment of a spacesuit, even the smallest spark can be catastrophic. A variety of energy harvesting options are explored with a focus on thermal energy harvesting. The temperature difference between the human skin and the astronaut’s Liquid Cooling and Ventilation Garment can be used to produce a small voltage. To increase the voltage a step-up converter is implemented. Final integration of the two systems with a biosensor is left for on-going work in the three year NASA project.
Still, Gwilym T. "Methods for reducing the cost of cementitious building components in developing countries, with particular reference to rainwater harvesting." Thesis, University of Warwick, 2007. http://wrap.warwick.ac.uk/2342/.
Full textRodriguez, Henry. "A Comparison of Rainwater Harvesting Tank Sizing Methods: Optimizing to Reduce Greenhouse Gas Emissions versus Maximizing System Reliability." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo151577155419202.
Full textRamaswamy, Maya. "Assessing occupational health among transitional agricultural workforces: a mixed methods study among U.S. beginning farmers and South Indian tea harvesting workers." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6251.
Full textLindemuth, Robert M. "A Field Trial Comparison of Sampling Methods for Estimating Basal Area and Volume in Partially Harvested Stands in Maine." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/LindemuthRM2007.pdf.
Full textDhayal, Vandana Sultan Singh. "Exploring Simscape™ Modeling for Piezoelectric Sensor Based Energy Harvester." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984261/.
Full textDrummond, Hazel. "Distribution and biomass of epiphytic seaweeds on the kelp Ecklonia maxima (Osbeck) Papenfuss, and the potential effects of two kelp-harvesting methods in the Western Cape." Bachelor's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/25563.
Full textXu, Sheng. "Oxide nanowire arrays for energy sciences." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42876.
Full textMeesala, Vamsi Chandra. "Modeling and Analysis of a Cantilever Beam Tip Mass System." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83378.
Full textMaster of Science
Fofana, Alpha, and Carl Mossberg. "Energy harvesting from ambient WiFi energy : A method of harvesting and measuring ambient WiFi energy." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-257860.
Full textMed den nuvarande utvecklingen inom trådlös teknik och IoT-domänen har efterfrågan på elektroniska applikationer med låg effekt ökat och en av utmaningarna är att hitta effektiva och hållbara sätt att driva dessa typer av enheter. Syftet med detta projekt var att undersöka frågan hur vi skördar radiovågsenergi och kan vi skörda tillräckligt mycket med energi för att den ska vara användbar i en applikation. I ett typiskt kontor finns fler källor till radiovågor, däribland WiFi som antas ha en hög nyttjandegrad. Projektet valde att inrikta sig på WiFi bandet och undersöka om det går att utvinna tillräckligt med energi där.Projektet strävade efter att leverera en färdig produkt med alla ingående delar, en antenn, en likriktare, en lagringsenhet och ett matchningsnätverk för att anpassa antenn och likriktare till varandra. För att undersöka hur mycket energi som finns att skörda gjordes först beräkningar och sedan mätningar i bland annat ett typiskt kontor. Det konstaterades att det rör sig om väldigt låga nivåer och betonas att de apparater som använder WiFi klarar av att känna av signaler som är långt mycket lägre än de som krävs för att kunna utvinna energi. Detta innebär alltså att apparaterna kan kommunicera felfritt samtidigt som energiinnehållet är så lågt att det inte går att utvinna någon energi.Projektet ägnar stor del åt att optimera den impedansmatchning som måste ske mellan antenn och likriktare för att största möjliga effektutbyte ska kunna ske. Basen är ett kretskort med ett typiskt impedansnätverk och genom beräkningar, simuleringar och experiment tas en prototyp fram. För att kunna analysera resultaten används en mikrokontroller som tar de analoga värdena, omvandlar dem till digitala och skickar dem till en PC för analys.Mätningar gjordes i en kontorsmiljö och den maximala mängden energi som gick att utvinna var 350 mJ på 24 timmar. Energin lagrades i en superkondensator och bedöms vara tillräcklig för att driva en lågenergisensor i ca 30 sekunder.
Quadros, Carlos Schmidt. "Rainwater harvesting case study: FCT/UNL campus." Master's thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/4799.
Full textWith increasing pressure on the environment, particularly on water resources, due to outside forces such as climate change and population growth, water is nowadays a scarce and a valuable resource. With the need to find new alternatives, rainwater harvesting should be seen as an important strategy for better management of water resources, once it constitutes a free source of potable water. Rainwater harvesting systems, which already have a global implementation, are a recognised way for urban buildings to reduce their reliance on the public mains supply. Its applications are predominantly non-potable, namely toilet flushing and gardening. The aim of this report is to produce a comprehensive assessment of rainwater harvesting and its potential use all over the world, as well as the potential economical and environmental benefits. It is provided a description of all the rainwater harvesting system components, as well as water quality requirements according to the water final purpose. A case study is presented, which main object is to evaluate the feasibility of rainwater harvesting for gardening, applied to the University Campus of the Faculty of Sciences and Technology of Universidade Nova, Lisbon (FCT/UNL). A detailed characterization of the existing irrigation system on campus is provided, as well as its potential ability to collect rainwater. According to the supply and demand balance, several scenarios are presented in order to provide the necessary information for the decision-makers to evaluate the best solution for the desired application. For such, all the available information was analyzed, in order to determine the environmental, technical and economical viability of the project.
Brandeau, Erich John. "An in-situ interdiffusion method for harvesting energy from an aluminum-water reaction." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74424.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 57-58).
Autonomous underwater vehicles (AUVs) are indispensable for countless underwater tasks but are currently limited in their range and endurance by the energy density of their battery packs. Aluminum is an ideal energy source for AUVs because it exothermically reacts with water and is two orders of magnitude more energy dense than current lithium-ion batteries. An in-situ interdiffusion method for reacting aluminum in water was conceived in which elemental aluminum is able to overcome the passivating aluminum oxide layer by diffusing into liquid gallium. The aluminum atoms in solution with the gallium react to produce heat and hydrogen gas when they reach the interface of the liquid gallium and water. This thesis attempts to quantify the diffusion of aluminum into liquid gallium as well as to quantify the reaction of the aluminum-gallium solution in water. Experiments are conducted to measure the diffusion and reaction rate constants, and the data is fit to the Arrhenius equation to predict the diffusion and reaction rates at elevated system temperatures. With the predicted diffusion and reaction rates, it was found how the size and temperature effect the power output of an in-situ inderdiffusion aluminum-water reactor.
by Erich John Brandeau.
S.B.
Triplett, Angela Lynn. "Vibration-Based Energy Harvesting with Essential Non-Linearities." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1322493879.
Full textRafique, Sajid. "Piezoelectric vibration energy harvesting and its application to vibration control." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/piezoelectric-vibration-energy-harvesting-and-its-application-to-vibration-control(d9edcedf-054e-4921-9ba3-5e015b9bbd8f).html.
Full textKim, Woon Kyung. "Design and Analysis of Switching Circuits for Energy Harvesting in Piezostrutures." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28646.
Full textPh. D.
Hassan, Mahmoud Wifag. "Water Harvesting for Integrated Water Resources Management and Sustainable Development in Khartoum State." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-125079.
Full textOLIVIERI, STEFANO. "Elastically-bounded flapping plates for flow-induced energy harvesting." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/999997.
Full textWang, Junjie. "Energy Harvesting Circuit for Indoor Light based on the FOCV Method with an Adaptive Fraction Approach." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/94319.
Full textMaster of Science
With the growing energy demands, the efficient energy conversion systems caught great attentions. Especially, in the era of Internet of Things, powering those wireless devices can be extremely difficult. Nowadays, lots of devices such as consumer electronics, wireless sensor nodes, computing and mission system etc. are still powered by the batteries. Regular changing the batteries of those devices can be inconvenient or expensive. Energy harvesting provides a good solution to this issue because there are lots of ambient energy source is available. To design an energy efficient energy harvesting circuit system can help extend the device lifecycle per charging cycle. Even with some specific energy source which power scale is high enough, meanwhile the load doesn’t require too much power, the devices can be power-independent or standalone. In this work, the proposed circuit targets for indoor solar energy harvesting via solar panel. The target powering devices are wireless sensor nodes (WSNs). Meanwhile, WSNs can monitor the temperature, humidity, pressure, noise level etc. The proposed circuit design combines the power stage and control circuit on an integrated chip (IC), only few components are off-chip. It provides a very compact, endurable, and economical solution to the current IoT powering issue.
Adamou, Djibrilla Incha. "Réseaux de collecte de données pour les zones blanches étendues." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS457/document.
Full textAlthough wide white areas are not equipped or sparsely equipped with any infrastructure (energy, roads ...), strategic human activities are being carried out such as mines, forest, pipeline... To tackle the problem of deploying sensor networks in a very large area where few infrastructures are available, we propose a network deployment algorithm which aims at efficiently linking sparse points of interest in a very wide white area. The originality of the proposed method is that it mimics the evolution of a type of mold called physarum. Secondly, we aim at overcoming the deployment problem in wide white areas by using long range communication between an aircraft and earth. The new data collection scheme he proposes is based on the use of commercial flights to collect data while they cross over an area of interest. It investigates the feasibility of such a scheme by determining the collection capacity of commercial aircraft in different locations of the desert. Finally, we mixed both solutions do repatriate data from sensors not covered by any flight to a covered data sink that relays data to the aircraft
Masghouni, Nejib. "Hybrid Carbon Fiber/ZnO Nanowires Polymeric Composite for Stuctural and Energy Harvesting Applications." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64354.
Full textPh. D.
Zhao, Xiaofei. "Harvesting Microalgae-Development of a Short Residence Time Method Using Rapid-response Temperature-sensitive Semi-IPN Hydrogels." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1434501731.
Full textSadeghi, Saviz. "Multi-criteria Spatial Evaluation and Modelling of Farm Dam Site Suitability for Water Harvesting and Conservation." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/16261.
Full textTurner, Kate. "Assessing wild plant vulnerability to over-harvesting: refinement of the "rapid vulnerability assessment" method and its application in Huitzilac, Mexico." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18450.
Full textPlusieurs critiques ont été formulées concernant l'impacts de la collecte des produits forestiers non ligneux (PFLN) sur les écosystèmes forestiers, ce qui a mené au développement d'outils afin d'évaluer la durabilité de la sous dite collecte. L'évaluation rapide de vulnérabilité (ERV) est une méthode afin de prédire la vulnérabilité de plantes à la sur collecte. Cependant, il y a peu de consensus sur la manière optimale d'effectuer une ERV ou d'interpréter les résultats obtenus. L'objectif de ma recherche est d'analyser et de raffiner la méthode ERV afin d'augmenter son utilité pratique. J'examine des facteurs influençant la vulnérabilité des plantes utilisées dans différentes versions de l'ERV afin de créer une liste abrégée de facteurs-clés. J'utilise ensuite cette liste abrégée afin d'effectuer une ERV sur une série de plantes sauvages sélectionnées à Huitzilac, au Mexique; dans le but d'améliorer la méthode ERV. L'information pour cette ERV provient de la littérature scientifique, des entrevues, des observations directes, l'échantillonnage de plantes et une évaluation d'utilisation en ville. Basée sur ces informations, je re-conceptualise la méthode ERV plaçant plus de valeur sur plusieurs facteurs critiques qui affectent directement l'existence et le taux de perte d'espèces sélectionnées. Je suggère également une méthode afin de faciliter l'interprétation de résultats. Les résultats de l'étude de cas, présentée de forme re-conceptualisée, indiquent qu'aucune des espèces sélectionnées n'est extrêmement vulnérable à la sur-collecte.
Perju, Dragos-Stefan. "Applying Memoization as an Approximate Computing Method for Transiently Powered Systems." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-256065.
Full textInternet of Things (IoT) håller på att bli en mer och mer utbredd teknik, eftersom det inte bara underlättar rutiner i vårt liv, utan det hjälper också industrin och företag att bli effektivare. Den höga potentialen med IoT kan också hjälpa till att ge stöd åt vår egen befolkning på jorden, genom precisionslantbruk, smart transport, smarta städer och mer. Det är därför viktigt att IoT görs skalbart på ett hållbart sätt för att säkra vår egen framtid.Det nuvarande arbetet handlar om transientdrivna system (TPS), vilket är inbäddade system som använder energiskörning som sin enda kraftkälla. I sin grundform har TPS ofta återställningar på grund av opålitlig tillgång till energi från miljön. Ursprungligen är därför sådana systems genomströmning lägre än deras batteriaktiverade motsvarigheter. För att förbättra detta använder TPS kontrollpunkter i RAM och processortillstånd till icke-flyktigt minne, för att hålla beräkningsförloppet sparat under strömförlustintervaller.Syftet med detta projekt är att sänka antalet kontrollpunkter som krävs under en applikationskörning på en TPS i ett generiskt fall, genom att använda ungefärlig datorberäkning. Energibehovet för TPS sänks med ungefärliga belopp, vilket innebär att fler resultat kommer när systemet arbetar mellan strömförlustperioder. För denna studie implementeras memoiseringstekniken i form av en hashtabell. Kalman-filtret tas som testapplikation för att köra på Microchip SAM-L11 inbäddad plattform.Memoization-tekniken lyckas ge en förbättring för Kalman-applikationen som beaktades, jämfört med den ursprungliga baslinjeversionen av programmet. En användare får ”balansera” mellan mer energibesparingar men mer felaktiga resultat eller motsatsen genom att justera en ”kvalitetsrat”-variabel epsilon ϵ. Till exempel, för en epsilon ϵ = 0.7, är förbättringen 32% färre kontrollpunkter som behövs än för baslinjeversionen, med en utdata avvikelse med 42% i genomsnitt och 71% vid sin högsta punkt.Beviset på konceptet har gjorts, att ungefärlig databeräkning verkligen kan förbättra genomströmning av TPS och göra dem mer genomförbara. Det påpekas dock att endast en enda applikationstyp testades, med ett visst inmatningsspår. Den implementerade hashtabellmetoden kan bete sig annorlunda beroende på vilken applikation och/eller data den arbetar med. Det föreslås därför att en föranalys av det specifika datasättet och applikationen kan göras vid designtidpunkten för att kontrollera genomförbarheten av att tillämpa ungefärliga belopp för det aktuella fallet.
Gisselman, Fredrik. "Economic assessment of harvesting and removing macro algae and reed as an eutrophication mitigation method : A cost-benefit analysis using an ecosystem service approach applied on Burgsviken Gotland." Thesis, Umeå universitet, Nationalekonomi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-99663.
Full textOdhiambo, Benedict O. "The use of time study, method study and GPS tracking in improving operational harvest planning in terms of system productivity and costs." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5333.
Full textENGLISH ABSTRACT: This study aims to quantify the benefits of implementing an operational harvesting plan in forest harvesting operations. This is to be achieved by comparing productivity and costs from unplanned and planned harvesting operations. The study was conducted on a Pinus radiata plantation owned by Mountain to Ocean Forestry Company (Pty) Ltd (MTO) located near the town of Grabouw in the Western Cape Province of South Africa. MTO conducts harvesting operations using semi-mechanised tree-length harvesting systems. A wheeled H67 Clark Ranger cable skidder is used to extract tree-lengths from infield to the landing. Data was obtained both manually (work study) and from GPS tracking. Choking and dechoking data was obtained through time and method studies. GPS tracking was used to measure travel loaded and travel empty times, as well as travel distances and travel speeds. The aim of using both manual techniques and GPS tracking was to obtain detailed and spatially accurate information about the operation. The operating costs were estimated using South African Harvesting and Transport Costing Model. Productivity of the newly introduced tagline system (45.97 m³/pmh) exceeded that of mainline system (37.85 m³/pmhh) by 26%. The unit production cost of using tagline system (R20.21/m³) was 10% lower than the unit production cost of using mainline system (R22.54/³3). There were no benefits to be gained from improving the level of skid trail construction by removal of logging residue or cutting down stumps to as near the ground level as possible. A combination of manual (time and method studies) data collection and GPS tracking provided more detailed and accurate information on the semi-mechanised harvesting system.
AFRKAANSE OPSOMMING: Hierdie studie beoog om die voordele van die uitvoering van 'n operasionele inoestingsplan te kwantifiseer. Dit word bereik deur produktiwiteit en kostes van beplande en onbeplande inoestingswerksaamhede te vergelyk. Die studie is gedoen in Pinus radiata opstande van Mountain to Ocean Forestry Company (Pty) Ltd (MTO) naby Grabouw in die Wes-Kaap provinsie van Suid Afrika. MTO gebruik semi-gemeganiseerde boomlengte inoestingstelsels in hul inoestingswerksaamhede. . H67 Clark Ranger wielsleeptrekker met kabel en wenas is gebruik om boomlengtes van die veld na die pad te sleep. Data is versamel deur van beide hand (werkstudie) en GPS-opsporing gebruik te maak. Afhaak en aanhaak data is verkry deur van tyd- en metodestudies gebruik te maak. Gelaaide en ongelaaide tyd, spoed en afstande is met behulp van die GPS gemeet. Deur van beide hand en GPS versamelingsmetodes gebruik te maak, kon omvattende sowel as ruimtelik akkurate inligting oor die werksaamhede verkry word. Die bedryfskostes is verkry van die South African Harvesting and Transport Costing Model. Produktiwiteit van die nuut ingestelde verbindingslynstelsel (45.97 m³/pmh) het die hooflynstelsel (37.85 m³/pmh) met 26% oorskry. Die eenheidsproduksiekoste van die verbindingslynstelsel (R20.21/m³) was 10% laer as die eenheidsproduksiekoste van die hooflynstelsel (R22.54/m³). Daar was geen voordeel in die verbetering van die sleeppad konstruksie deur afval te verwyder of stompe nader aan die grondvlak af te sny nie. 'n Kombinasie van hand (tyd- en metodestudies) dataversameling en GPS-opsporing het meer akkurate en omvattende inligting oor die semi-gemeganiseerde inoestingstelsel verskaf.
Yan, Zhimiao. "Modeling of Nonlinear Unsteady Aerodynamics, Dynamics and Fluid Structure Interactions." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71824.
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Topal, Emre Tan. "A Mems Thermoelectric Energy Harvester For Energy Generation In Mobile Systems." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613636/index.pdf.
Full textT values. The performance of the MEMS TE energy harvesters was optimized using analytical and 3-D finite element models. An analytical code was used for profiling the electrical power output with varying geometry. The design points with maximum generated power were selected, and the microfabricated thermoelectric energy harvesters were designed accordingly. The fabricated devices are formed on a silicon wafer and composed of Nickel and Chromium thermocouples on SiO2/Si3N4 diaphragms, and Titanium heater and monitor resistors for testing purposes. Microfabrication was followed by the performance characterization of MEMS TE energy harvesters with the conducted tests. For 10 °
C temperature difference between the hot and cold junctions (a heat source at 35 °
C), the proposed TE energy harvesters are capable of providing 1.1 µ
W/cm2 power density and 1.71 V voltage. The performance of the thermoelectric generators in general is limited by Carnot cycle efficiency. Nevertheless, the validated practical performance of MEMS TE energy harvesters proposed in this thesis is comparable to other examples in literature. It is anticipated by the calculations that this design will be able to provide the highest thermoelectric efficiency factor (4.04 µ
W/K2cm2) among the lateral TE energy harvesters if thermoelectric materials having high Seebeck coefficient values (such as p-Si, n-Si, polysilicon, Bi2Te3 etc.) are used. According to the performance results, the MEMS TE energy harvesters can be implemented in mobile systems to convert waste heat into electricity. The fabrication process can be adapted to CMOS with some modifications if needed. The lateral MEMS thermoelectric energy harvesters can also be combined with vibration energy harvesters to realize multi-mode energy scavenging. For prospective study, vertical thermoelectric generator configurations are also discussed in order to further increase the power density generated. The finite element simulations for proposed vertical configurations with air and water convection were completed. The vertical TE generators proposed can supply up to 4.2 mW/cm2 with a heat source at a temperature of 310 K.
Sijková, Simona. "Návrh testovacího přípravku piezoelektrických vlastností PVDF vrstvy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417737.
Full textDeng, Jie. "Vibroacoustic modeling of acoustic blackhole applications in flat, curved andcomplex mechanical structures." Doctoral thesis, Universitat Ramon Llull, 2020. http://hdl.handle.net/10803/670666.
Full textLos agujeros negros acústicos en mecánica (conocidos por las siglas ABHs, del inglés Acoustic Black Holes) suelen estar formados por muescas en vigas y placas, el grueso de las cuales decae según una ley potencial. El efecto del ABH es el de ralentizar las velocidades de fase y de grupo de las ondas de flexión incidentes de tal modo que, en teoría, haría falta un tiempo infinito para que las ondas alcanzaran el centro del ABH, si el grueso de este último fuera exactamente cero. Sin embargo, en la práctica esto no es posible, aunque se puede conseguir una fuerte disipación colocando una capa de material amortiguador en el centro del ABH, donde se concentra la mayor parte de la energía de las ondas. En los últimos años, los ABHs no sólo se han explotado como método pasivo para reducir vibraciones estructurales y la consecuente emisión de ruido, sino que también se ha explorado su potencial para otras aplicaciones como la manipulación de ondas o la captación de energía. Esta tesis tiene tres objetivos principales. Así pues, tras una introducción general a los ABHs, el trabajo se ha dividido en tres grandes secciones. La primera aborda aplicaciones de los ABHs en vigas rectas y placas planas. Para empezar, se propone y analiza un voladizo piezoeléctrico con un acabado de ABH para capturar energía. A continuación, se presentan ABHs en forma de anillo para aislar puntos de excitación externos en placas planas y así evitar la transmisión de vibraciones. Finalmente, se contemplan configuraciones periódicas de matrices de ABHs para colimar haces de ondas de flexión y concentrar su energía en zonas predeterminadas de una placa. La segunda parte de la tesis propone nuevos diseños de ABHs para estructuras con curvatura. Estas son muy habituales en los sectores naval, aeronáutico e industrial, por lo que merece la pena investigar si los ABH pueden dar buenos resultados en algunos casos. La sección comienza analizando la inclusión de ABHs en vigas circulares y se ve como estos dan pie a la aparición de fenómenos típicos de sistemas periódicos. Seguidamente se propone un ABH anular para reducir las vibraciones en conductos cilíndricos. En concreto, se tratan los casos de un conducto simplemente soportado con un ABH anular, y el de un conducto con ABH, soportes periódicos y rigidificadores. Para finalizar la sección, se investigan los efectos de los ABH anulares en la radiación acústica del conducto teniendo en cuenta el nivel de potencia acústica, la eficiencia de radiación y la intensidad supersónica. La tercera parte de la tesis es más corta que las anteriores y simula el aislamiento de una placa con múltiples ABHs, en el rango de media y alta frecuencia. A tal efecto se emplea el método del análisis estadístico de distribución modal de energía (SmEdA: statistical modal energy distribution analysis). En esta sección, la estructura con ABHs ya no se analiza como un elemento individual, sino que se acopla a dos cavidades de aire formando parte de un sistema mecánico más complejo. A lo largo de la tesis se utiliza repetidamente el método de expansión gaussiana (GEM: Gaussian expansión method). Por GEM entendemos tomar funciones gaussianas como base para resolver ecuaciones diferenciales en derivadas parciales en el marco del método de Rayleigh-Ritz. El GEM se parece mucho a los enfoques de ondículas, pero ofrece algunas ventajas en el caso de condiciones de contorno periódicas. Al principio de la tesis se expone un breve repaso del GEM y, cuando es necesario, se aborda su reformulación para un problema particular en el capítulo correspondiente.
Acoustic black holes (ABHs) in mechanics usually consist of geometrical indentations on beams and plates having a power-law decreasing thickness profile. An ABH slows down the phase and group velocity of incident flexural waves in such a way that, ideally, it would take an infinite amount of time for them to reach the ABH center, if the latter had an exact zero thickness. Though this is not possible in practice, strong wave dissipation can be achieved by placing a damping layer at the central region of the ABH, where most vibration energy concentrates. In recent years, ABHs have been not only exploited as a passive means for structural vibration and noise reduction, but its potential for other applications like wave manipulation or energy harvesting have been also explored. The objective of this thesis is threefold. Therefore, after an initial overview the work is divided into three main parts. The first one deals with ABH applications on straight beams and flat plates. To start with, an ABH piezoelectric bimorph cantilever for energy harvesting is proposed and analyzed. Then, ring-shaped ABH indentations are suggested as a means of isolating external excitation points in flat plates and prevent vibration transmission. Finally, periodic ABH array configurations are contemplated to collimate flexural wave beams and focus energy at desired plate locations. The second part of the thesis proposes new ABH designs for curved structures. The latter are very common in the naval, aeronautical and industrial sectors so it is worth investigating if ABHs could function for them. The section starts analyzing the embedding of ABHs on circular beams and how this results in the appearance of typical phenomena of periodic systems. After that, an annular ABH is proposed to reduce vibrations in cylindrical shells. The cases of a simply supported shell with an annular ABH indentation and of a periodic simply supported ABH shell with stiffeners are considered. To finish the section, the effects of annular ABHs on sound radiation are investigated in terms of sound power level, radiation efficiency and supersonic intensity. The third part of the thesis is shorter than the previous ones and is devoted to analyzing the transmission loss of a plate with multiple ABH indentations, in the mid-high frequency range. Statistical modal energy distribution analysis is used for that purpose. Here, the ABH plate is not taken as an individual structure but coupled to two air cavities, thus being part of a more complex mechanical system. Throughout the thesis repeated use is made of the Gaussian expansion method (GEM). The GEM refers to taking Gaussian functions as the basis for solving partial differential equations in the framework of the Rayleigh-Ritz method. The GEM closely resembles wavelet approaches but offers some advantages in the case of periodic boundary conditions. A brief overview of the GEM is exposed at the beginning of the thesis and, when necessary, its reformulation for a particular problem is tackled in its corresponding chapter.
Hoang, Thien. "Dispositif de récupération d'énergie piézoélectrique : modélisation, fabrication et caractérisation." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4023.
Full textThis thesis is part of the Lab-TMEMS project, a collaboration between the GREMAN laboratory and the VERMON Company. The goal of this project is to realize miniaturized piezoelectric devices harvesting energy from low frequency vibrations in order to supply devices used in biomedical applications, for example. Thus, the objective of this thesis is to propose a strategy for the design and optimization of such devices. In order to achieve this objective, we have developed an original approach of modeling by finite element method in three-dimensional space in order to model the whole structure of the harvester. After being validated experimentally, our design tool is used to optimize the piezoelectric harvester according to given specifications. This design tool for linear piezoelectric harvesters design was developed based on geometrical parametric studies in linear domain. By using this tool, we have designed, fabricated and characterized the optimized piezoelectric harvester. Then we integrated it into an autonomous wireless sensor used for the preventive maintenance of an industrial rotating machine. The power recovered from the harvester, coupled with its power management circuit, is sufficient to power the sensor, making it autonomous
Brites, Alice Dantas. "Monitoramento dos efeitos ecológicos e socioeconômicos da comercialização de produtos florestais não madereiros." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/90/90131/tde-24032011-215203/.
Full textAmazon, non-timber forest products, ecological effects, socioeconomic effects, monitoring.
Elliott, Robert Bailey. "Quantitative Comparison of Mechanical Harvesting Methods and Conventional Harvesting Methods of Burley Tobacco in the Southeast." 2008. http://trace.tennessee.edu/utk_gradthes/374.
Full textKim, Hyeoungwoo. "Impedance adaptation methods of the piezoelectric energy harvesting." 2006. http://www.etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-1258/index.html.
Full text"Biogeochemistry of forest harvesting methods in the boreal zone of Quebec." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/24124/24124.pdf.
Full textHamann, Mark Thomas. "Impact of Cotton Harvesting and Storage Methods on Seed and Fiber Quality." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10230.
Full textFontes, Tomás Miguel Guedes. "Methods of adipose tissue harvesting and preparation for autologous grafting in reconstructive surgery." Master's thesis, 2017. https://hdl.handle.net/10216/105207.
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