Dissertations / Theses: 'Harvester'

1

Lewis, Andrew Geoffrey. "Automated Asparagus Harvester Feasibility Study." Thesis, University of Canterbury. Engineering Management, 2013. http://hdl.handle.net/10092/7442.

Full text

Abstract:

The Tendertips Company (TTC) is an asparagus growing a packing business which has a problem. Not enough New Zealanders are willing to manually harvest asparagus. Samoan workers are being employed through the recognised seasonal employer (RSE) scheme which incurs a large cost to TTC. This scheme is also susceptible to a change in government policy at any time. Automated asparagus harvesters have been designed in the past however they inflict too much damage to asparagus plants and the paddocks in which they grow. Several research projects have also been undertaken to minimise this damage while robotically harvesting asparagus however no solutions currently exist. In this project a low-cost system was designed and constructed to determine the feasibility of selectively harvesting asparagus without inflicting damage to asparagus plants or the paddock. The most technical component in this system was identified, accurately identifying and locating asparagus spears to be harvested. A camera and lighting system, along with an asparagus data logging system was designed and tested, with the assumption that if this system succeeded, the development of an automated asparagus harvester would have a very high chance of success. The system proved that individual asparagus spears can be located accurately enough so as not to inflict damage on other spears during the harvesting process: • 96.8% of asparagus spears were located. • Average location error of 3.0mm. The measurement of the size and height of asparagus spears was not very accurate due to the lighting system, however this is expected to be fixed with a design change. A global positioning system (GPS) successfully saved the calculated size of the asparagus spear with its global location to allow for analysis of the asparagus paddocks using the Google Earth application. The cost of robotically harvesting asparagus is forecast to be much less than manual harvesting: • Manual harvesting cost $1.40 per kilogram • Forecast robotic harvesting cost $0.41 per kilogram. If one other investor was obtained to create a new business, which developed an automated asparagus harvester before harvesting asparagus in New Zealand and California, the forecast financials are: • Net present value (NPV) of $1.613 million after ten years. • Internal rate of return (IRR) of 33% after ten years. • Maximum accumulated investment from TTC of $449,000 four years after development first begins. The forecast income is through harvesting asparagus only as selling the machines or leasing the intellectual property is not viable. A guiding document was created to guide TTC with the development of an automated asparagus harvester if it aligns with their business model. The development of an automated harvester: • Is technically viable. • Will lower harvesting costs. • Will ensure all of TTC’s asparagus is harvested when required. • Will return sustainable profits to the child business that TTC should create. The project management techniques adopted in this project ensured the project was completed on the planned day of completion, while remaining on budget: • Budgeted cost of work scheduled $24,478.21 • Budgeted cost of work performed $24,027.54

APA, Harvard, Vancouver, ISO, and other styles

2

Angulo, Ignacio. "Harvester Energy Modelling and Optimization." Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-192131.

Full text

Abstract:

Denna rapport är resultatet av ett examensarbete på Kungliga Tekniska Högskolan i samarbete med Skogforsk. Syftet är att analysera den trädkapningsprocessen hos en skördare, optimera dess energiförbrukning och föreslå modifieringar av systemet. En analys av skördarhuvudets energiförbrukning genomfördes baserat på testdata från Skogforsk. Denna undersökning gav en inblick i prestandan hos hydraulmotorn Parker F11-19 vid kapnng av träd med varierande diameter, samt en kvantifiering av mängden energi som används av skördarhuvudets olika komponenter. Hydrauliska och mekaniska modeller av skördarhuvudet skapades med hjälp av simuleringsverktygen Hopsan och Simulink. Dessa modeller användes för att verifiera optimeringsförslagen. Resultatet av denna studie är fyra optimeringslösningar för ett skördarhuvud. Det första förslaget är att använda en ackumulator för kinetisk energiåtervinning i matningsrullarna, vilket kommer att bidra med en minskning av energiförbrukningen med 6.85%. Det andra förslaget är att optimera sågcylinderns position, vilket kommer leda till en reduktion med 0%, dvs aktuell position bedöms vara optimal. Det tredje förslaget är förändring av kvistknivarnas utformning, vilket minskar energiförbrukningen med 2.72%. Det fjärde förslaget är att använda en alternativ motor som kräver mindre energi, vilket bidrar till en markant minskning av energiförbrukningen med 28.4%. Totalt kommer de föreslagna förändringarna att resultera i en reduktion av energiförbrukningen med 37.9%. Resultatet är teoretiskt och ytterligare fält- och riggprov är nödvändiga för att validera resultaten.
This report is the result of the Master of Science thesis project developed for KTH Royal Institute of Technology in collaboration with the Forestry Research Institute of Sweden (Skogforsk) for the Forestry Master Thesis School 2016. The purpose is to analyze the tree cutting process of a harvester machine, optimize the energy consumption and propose modifications to the system of components if applicable. A study on the energy usage of a harvester head was performed based on test data gathered by Skogforsk, providing insight about the performance of the hydraulic motor Parker F11-19 when cutting different tree diameters and quantifying the amount of energy used on each part of the harvester head. Hydraulic and mechanical models of the head were built using Hopsan and Simulink, respectively. These models were used for the verification of the optimizations proposed. The results from this research study are four optimization solutions for a harvester head. The first suggestion is to use an accumulator for kinetic energy recovery in the feeding rollers, which will contribute with a reduction in energy consumption of 6.85%. The second suggestion is to optimize the saw’s cylinder position, which did not provide any improvements. The third suggestion is a redesign of the delimbing knives, which will reduce the energy consumption with 2.72%. And the final suggestion is to use an alternative motor that requires less power, which will result in a significant decrease of energy consumption by 28.4%. In total, the changes suggested will result in a reduction of the energy consumption by 37.9%. The results are theoretical and further testing in practice is needed in order to assess the veracity of the results.

APA, Harvard, Vancouver, ISO, and other styles

3

Baldassarri, Mirko. "Review of Vibration Energy Harvester." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

Find full text

Abstract:

This work presents a state-of-the-art on vibration energy harvesting that is one of the hottest topics addressed by a big part of the scientific community to minimize the requirement of external power source. A lot of transduction mechanisms have been investigated and designed by researchers, based on different mechanical systems and transduction principles, in order to recover energy coming from environmental vibrations. This dissertation is intended to illustrate and analyse the main findings in order to highlight the critical aspects of this technology and the key challenges for further developments. Firstly, a classification of vibration energy harvesters (VEHs) based on their "oscillating structures" and "transduction mechanisms" is provided, corresponding to the most widely used mathematical reference model and transduction devices, respectively. Then, the most common examples of application of such devices is presented to illustrate how vibrations of the surrounding environment can be converted into electrical energy exploited for different intended uses. Based on this survey, the limitations of the simplest devices are discussed, the most important of which is the ineffectiveness of VEHs when prompted by vibrations with a frequency even slightly different from the device resonance frequencies, (which is a common scenario, since environmental vibrations are often random and broadband). To solve this problem, researchers are currently focusing on developing efficient VEHs by adopting new materials and optimising the harvesting devices. The recent prototypal devices appear promising, but the achievement of robust solutions for real practical applications still seems a long-term goal, due to the limited capability of current technology to harvesting meaningful levels of electrical energy.

APA, Harvard, Vancouver, ISO, and other styles

4

Eliasson, Lars. "Analyses of single-grip harvester productivity /." Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5614-2.gif.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Hajati, Arman. "Ultra wide-bandwidth micro energy harvester." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/63072.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 189-197).
An ultra wide-bandwidth resonating thin film PZT MEMS energy harvester has been designed, modeled, fabricated and tested. It harvests energy from parasitic ambient vibration at a wide range of amplitude and frequency via piezoelectric effect. At the present time, the designs of most piezoelectric energy devices have been based on high-Q linear cantilever beams that use the bending strain to generate electrical charge via piezoelectric effect. They suffer from very small bandwidth and low power density which prevents them from practical use. Contrarily, the new design utilizes the tensile stretching strain in doubly-anchored beams. The resultant stiffness nonlinearity due to the stretching provides a passive feedback and consequently a wide-band resonance. This wide bandwidth of resonance enables a robust power generation amid the uncertainty of the input vibration spectrum. The device is micro-fabricated by a combination of surface and bulk micro-machining processes. Released devices are packaged, poled and electro-mechanically tested to verify the wide-bandwidth nonlinear behavior of the system. Two orders of magnitude improvement in bandwidth and power density is demonstrated by comparing the frequency response of the system with that of an equivalent linear harvester with a similar Q-factor.
by Arman Hajati.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

6

Larson, Geremy. "Self-propelled forage harvester sales analysis." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/35746.

Full text

Abstract:

Master of Agribusiness
Department of Agricultural Economics
Major Professor Not Listed
Self-propelled forage harvesters are used to make feed for livestock. Producers prefer forage made with these machines because they are able to deliver a feed value that enables improved productivity of their animals in terms of milk production for dairy animals and weight gain for beef animals. Self-propelled forage harvesters are able to make a variety of feed from different crops, including whole-plant corn silage, earlage, and haylage, among others. The self-propelled forage harvester is a complex and expensive piece of machinery for a producer to own. The self-propelled forage harvester market in the United States is a growing market, but small when compared to other equipment such as combines. In today’s environment, productivity is crucial to the success of the agricultural producer. Self-propelled forage harvesters are no exception. Growth of the self-propelled forage harvester market is reflected in increased unit sales, total horsepower sold, and average horsepower of the selfpropelled forage harvesters sold in the United States. This study looks at changes in the number and size of self-propelled forage harvesters being purchased and what factors might be driving those changes. This study found that the amount of milk produced, the type of customer purchasing the equipment, and the average price of milk a producer received explained 81.2% of the variation in the number of self-propelled forage harvesters sold from 2000- 2014. Study results also show that the size of dairy operation, the type of customer purchasing the equipment, and the average price of milk explained 88% of the variability in total horsepower of self-propelled forage harvesters sold from 2000-2014. Finally, the size of dairy operation that a typical cow comes from, the type of customer purchasing the equipment, and the average price of corn were able to explain 98% of the variation of average horsepower of self-propelled forage harvesters over that same time period. The model and analysis will be shared with product planners from John Deere as they develop new machine specifications for self-propelled forage harvesters in the future.

APA, Harvard, Vancouver, ISO, and other styles

7

Smith, Christopher Ryan. "Florida harvester ants and their charcoal." [Tallahassee, FL : Florida State University], 2004. http://etd.lib.fsu.edu/theses/available/etd-06282004-170836.

Full text

Abstract:

Thesis (M.S.)--Florida State University, 2004.
Advisor: Dr. Walter R. Tschinkel, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed Sept. 24, 2004). Includes bibliographical references.

APA, Harvard, Vancouver, ISO, and other styles

8

Michelon, Dino. "UHF energy harvester in CMOS technology." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4322.

Full text

Abstract:

Un des défis majeurs de l’Internet des Objets et, plus généralement, des tous les réseaux de capteurs sans fils, c’est l’alimentation de chaque nœud connecté. La solution la plus commune est d’équiper chaque dispositif d’une batterie mais cela introduit plusieurs contraintes, qui mettent en question la faisabilité de cette approche sur le long terme (durée de vie limité, couts de gestion élevé, empreinte écologique).Cette thèse développe une possible solution basée sur la transmission sans-fils de l’énergie. Un récupérateur d’énergie RF, composé d’une antenne, un redresseur haute-fréquence et un convertisseur élévateur, est présenté. Ce système permet de récupérer les ondes électromagnétiques et de produire une tension continue en sortie, qui peut être utilisé pour alimenter des microcontrôleurs ou des capteurs. L’absence d’une batterie interne augmente la flexibilité globale, surtout pour les situations où le remplacement n’est pas possible (ex. dispositifs implantés, nombre élevé de nœuds, milieux dangereux). Une étude approfondie sur les redresseur intégrés ultra-haute-fréquence de type Schottky et MOS a été mené ; plusieurs topologies ont été analysées et optimisées. De plus, l’utilisation d’un convertisseur élévateur a été envisagée, dans le but d’accroitre la tension en sortie ; une première version discrète et puis une plus compacte version intégrée, ont été abordées et testées. Ces développements ont permis d’aboutir à un récupérateur complet, potentiellement capable d’alimenter un microcontrôleur du commerce
One of the challenges of the Internet of Things and, more in general, of every wireless sensor network is to provide electrical power to every single one of its smart nodes. A typical solution uses batteries but various major concerns reduce the long-term feasibility of this approach (limited lifetime, maintenance and replacement costs, and environmental footprint).This thesis develops a possible solution based on the wireless transmission of power. A complete RF harvester composed of an antenna, a UHF rectifier and a step-up voltage converter is presented. This system captures electromagnetic waves and converts them to a stable DC voltage to supply power to common logic circuits like microcontrollers and sensors. The lack of an internal battery provides an extended flexibility, especially when its replacement is not a viable option (ex. implanted devices, large number of nodes, dangerous environments, etc.). An in-depth study of integrated Schottky and CMOS UHF rectifiers is carried out; various topologies and optimizations are analyzed. Moreover, the use of an additional step-up converter is proposed in order to increase the system output voltage; an early discrete implementation and a final, more compact, integrated version are discussed and tested. These developments lead to a complete system capable of potentially powering an application with an off-the-shelf microcontroller

APA, Harvard, Vancouver, ISO, and other styles

9

Hehn, Thorsten [Verfasser], and Yiannos [Akademischer Betreuer] Manoli. "A CMOS Integrated Interface Circuit for Piezoelectric Energy Harvesters = Eine CMOS-Integrierte Schnittstellenschaltung für Piezoelektrische Energy Harvester." Freiburg : Universität, 2014. http://d-nb.info/1123479119/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Deterre, Martin. "Toward an energy harvester for leadless pacemakers." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00868838.

Full text

Abstract:

This work consists in the development and design of an energy harvesting device to supply power to the new generation pacemakers, miniaturized leadless implants without battery placed directly in heart chambers. After analyzing different mechanical energy sources in the cardiac environment and associated energy harvesting mechanisms, a concept based on regular blood pressure variation stood out: an implant with a flexible packaging that transmits blood forces to an internal transducer. Advantages compared to traditional inertial scavengers are mainly: greater power density, adaptability to heartbeat frequency changes and miniaturization potential. Ultra-flexible 10-µm thin metal bellows have been designed, fabricated and tested. These prototypes acting as implant packaging that deforms under blood pressure actuation have validated the proposed harvesting concept. A new type of electrostatic transducer (3D multi-layer out-of-plane overlap structure with interdigitated combs) has been introduced and fully analyzed. Promising numerical results and associated fabrication processes are presented. Also, large stroke optimized piezoelectric spiral transducers including their complex electrodes patterns have been studied through a design analysis, numerical simulations, prototype fabrication and experimental testing. Apower density of 3 µJ/cm3/cycle has been experimentally achieved. With further addressed developments, the proposed device should provide enough energy to power autonomously and virtually perpetually the next generation of pacemakers.

APA, Harvard, Vancouver, ISO, and other styles

11

He, Cairan. "Elasrostatic micro energy harvester with rolling mass." Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529376.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Shin, Abraham. "A MEMS magnetic-based vibrational energy harvester." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119573.

Full text

Abstract:

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 81).
This thesis presents the design, fabrication, and testing of a MEMS vibration energy harvester that is to operate at low frequency to power machine health monitoring. The energy harvester converts external vibration into electricity via the Lorentz-force by allowing a permanent magnet, which acts as an inertial mass, to oscillate between coils wound above and below the magnet. Careful analysis and design of a fabricated silicon-based suspension, which holds the magnet, determines the important mechanical properties of the harvester, such as the internal loss and the selectivity of a single translational vibration. The harvester is designed to provide maximum power output at 0.5 g external acceleration at 50 Hz while its size is constrained to be less than 1 cm3. By incorporating mechanical and electromagnetic analyses, a full-system optimization is performed to determine the optimal dimensional parameters of the harvester and to estimate the power output to be observed. The fabricated and assembled energy harvester is tested and observed to produce an open-circuit voltage of 100 mV and a power output of 165 [mu]W at the resonance frequency of 45.7 Hz. The harvester's power density is 382 [mu]W/cm3, which is higher than the highest reported value of 222 [mu]W/cm3 for existing MEMS energy harvesters, but the performance of the design presented in this thesis may be improved with some changes to the current design.
by Abraham Shin.
M. Eng.

APA, Harvard, Vancouver, ISO, and other styles

13

Yuan, Yue. "Backpack Energy Harvester with Human Walking Model." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/77920.

Full text

Abstract:

The objective of this thesis is to design, analyze, and fabricate an innovative backpack energy harvester for human walking. To model human walking with backpack energy harvester, a simple dual-mass model has been developed and studied first. Dual-mass model for three types of distinct harvesters were investigated, pure damping, traditional rack pinion energy harvester and our MMR based energy harvester. A comparison in the output power and human comfort between the three types of harvesters is discussed. However, the dual-mass model could not effectively represent human walking in real situation with sinusoidal input, like M shaped Ground Reaction Force (GRF), vertical Center of Mass (COM) motion, etc. Thus, a bipedal walking model has been proposed to simulate human walking with backpack harvester. Experiments were conducted to compare power output and efficiency of MMR based backpack energy harvester with traditional rack pinion backpack energy harvester, and verify conclusions from the bipedal walking model that the proposed backpack energy harvester using mechanical motion rectifier (MMR) mechanism has larger power output than traditional backpack energy harvester at different walking speed. In human treadmill test, subjects were asked to wear the backpack frame which embedded with harvesters walking on a treadmill. Two walking speed, 3mph and 3.5mph, and four resistor values has been tested. The test results showed that the MMR based backpack energy harvester generated more power regardless of resistor values and walking speed. Up to 4.84W average power and instant power of 12.8W could be obtained while the subject walking on the treadmill at 3.5mph speed with MMR based backpack energy harvester.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

14

Purfürst, Thomas. "Der Einfluss des Menschen auf die Leistung von Harvestersystemen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-19722.

Full text

Abstract:

Produktivitätsmodelle geben Auskunft darüber, welche Leistung mit einem bestimmten Verfahren unter konkreten Rahmenbedingungen zu erwarten ist. In der Forstwirtschaft sind sie für Planungen und Kalkulationen notwendig. In bisherigen forstlichen Produktivitätsmodellen für den Maschineneinsatz wurde der Faktor Mensch, welcher einen wichtigen, bisher jedoch weitestgehend unbekannten Einfluss auf die Leistung hat, vernachlässigt. Ziel der vorliegenden Untersuchung ist es daher, den menschlichen Einfluss auf die Leistung von Harvestersystemen quantitativ zu erfassen und ihn in Produktivitätsmodelle einzubauen. Die Untersuchungsgrundlage bilden Leistungsmessungen, die mit vier verschiedenen Datenerhebungsverfahren an bis zu 32 Fahrern erfolgten. Neben einer neu entwickelten, sensorgestützten, semiautomatischen Zeitstudienmessung fand die Auswertung von summarischen Bordcomputer-Bestandesdaten über einen Zeitraum von drei Jahren Anwendung. Weiterhin erfolgte die (Weiter-)Entwicklung eines standardisierten Parcourstests, welcher auf einer Freifläche durchgeführt wird sowie eine Beurteilung der Leistung der Harvesterfahrer durch Gutachter. Alle vier Verfahren wurden miteinander verglichen und auf ihre Treffsicherheit und Aussagefähigkeit hin überprüft. Dabei konnten signifikante Korrelationen zwischen allen vier Datenerhebungsverfahren nachgewiesen werden, was eine Umrechnung untereinander grundsätzlich zulässt. Im Rahmen dieser Untersuchungen konnte die Vermutung quantitativ bestätigt werden, dass große, signifikant unterschiedliche Leistungshergaben zwischen den verschiedenen Harvesterfahrern existieren. Dies gilt nicht nur für den Vergleich zwischen so genannten „unerfahrenen“ und „erfahrenen“ Maschinenführern. Auch zwischen schon lange auf den Erntemaschinen arbeitenden Fahrern ist ein Leistungsunterschied von bis zu 80% zu verzeichnen. Somit ist die Beachtung des Parameters „Mensch“ für präzise Produktivitätsmodelle zwingend erforderlich. Der ursprüngliche Lösungsansatz, ein allgemein gültiges Produktivitätsmodell zu entwickeln, in dem der Einfluss des Menschen berücksichtigt wird, wurde aufgrund von Informationsdefiziten sowie zu starken Unterschieden und Komplexität der vorhandenen Modelle verworfen. Mit dem neu gewählten Lösungsansatz, der die Bestimmung eines Leistungswertes für jeden Fahrer vorsieht, ist es nun möglich, ein beliebig erstelltes Produktivitätsmodell linear auf ein Basisniveau zu normieren. Die Multiplikation des normierten Modells mit dem Leistungswert eines Fahrers ermöglicht es, die wahrscheinlich von ihm zu erwartende Produktivität zu berechnen. Dieser Wert kann auf verschiedene Weisen erhoben werden. Als Ergebnis dieser Arbeit kann dafür der entwickelte, schnell und einfach durchzuführende Parcourstest empfohlen werden. Er erreicht eine ungefähre Treffgenauigkeit von ±10%. Die Untersuchungen wiesen des Weiteren aus, dass beim Harvestereinsatz unter einfachen Umwelt- und Geländebedingungen der Fahrereinfluss auf die Produktivität bei 37% liegt. Er stellt somit nach Baumvolumen des ausscheidenden Bestandes (46%) den zweitwichtigsten Einflussfaktor dar. Die Leistungshergabe des einzelnen Harvesterfahrers ist nicht immer gleich, sondern verändert sich über der Zeit (Lernkurve). Die gemessenen Lerngeschwindigkeiten variieren dabei zwischen den Harvesterfahrern sehr stark. Das Anlernen eines unerfahrenen Harvesterfahrers dauerte bei den untersuchten Probanden im Mittel neun Monate, was einer Minderleistung von ca. 24% über diesen Zeitraum entspricht. Die bisherigen angenommenen Modelle der Lernkurve konnten bestätigt werden. Darüber hinaus zeigten sich Tendenzen, dass die Leistung der Fahrer nach der Lernphase ein konstantes Leistungsniveau erreicht, allerdings bei einer hohen Fehlerabweichung. Durch die Beurteilung und Berücksichtigung der Leistungen der Fahrer steht der Forstwirtschaft ein Werkzeug zur Verfügung, mit dem man in Zukunft die erstellten Produktivitätsmodelle für den Harvestereinsatz genauer auf die jeweiligen individuellen Gegebenheiten des eigenen Betriebes anpassen kann. Die Übertragung des gewählten Lösungsansatzes auf weitere Forstmaschinen, die von Menschen bedient werden, sollte geprüft werden
Productivity models provide information about the expected performance of a given procedure under specific conditions. In forestry, they are essential to planning and cost estimation. In hitherto existing productivity models of forest machinery, however, the human being as an important yet mostly unknown factor influencing productivity has been disregarded. Therefore, the objectives of this study are the quantification of the human impact on the performance of forest harvesting systems and its integration into productivity models. The study is based on performance measurements collected using four different methods of data acquisition to monitor up to 32 machine operators: (i) a newly developed sensor-based semi-automatic time study, (ii) the extraction of on-board computer data accumulated over a 3-year period, (iii) an improved standardized machinery test course conducted in an open area, and (iv) the expert evaluation of operator performance. The four data acquisition methods were compared and tested for data accuracy and informational value. All correlations between data yielded by each of the four methods were significant, thus in principle allowing for data conversion between data rendered by different acquisition methods. The results of this study quantitatively corroborate the presumption of major, significantly different performances between harvester operators. This holds true not only for the comparison of so-called ‘inexperienced’ and ‘experienced’ machine operators, but also when exclusively comparing experienced operators with each other. A performance difference of up to 80% has been observed between individuals featuring long-term experience in operating harvesting machinery. The integration of the parameter ‘human being’ is thus an imperative for precise productivity models. The original aim of developing a general productivity model accounting for human influence had to be abandoned due to an information deficit, substantial differences between the existing models as well as their inherent complexity. Instead, the new approach of determining a performance indicator for each individual machine operator now allows for the linear standardisation of any productivity model. By multiplying the standardised model with the performance indicator of a particular operator the probable performance to be expected of this operator can be calculated. This value can be determined in various ways. Based on this study, the test course value can be recommended, which was explicitly developed for fast and simple assessment of operator performance and achieves an accuracy of ±10%. The study results show that under favourable environmental conditions and on easy terrain the influence of the machine operator on overall performance amounts to 37%. The human factor is thus second only to the average volume of harvested trees (46%) with respect to influencing performance. The performance of an individual harvester operator is not constant, but changes over time (learning curve). The measured rate of learning largely differed between operators. The initial training of an inexperienced harvester operator took on average nine months, which corresponds to a performance deficiency of approx. 24% throughout this time period. Hitherto developed models of learning curves were corroborated by the study results. Performance levels following the initial training period tended to remain constant over time, but were characterised by large error margins. The evaluation and consideration of operator performance presents a forest management tool which allows for future customization of existing productivity models of harvesting machinery to the specific conditions and economics of any individual forest enterprise. The extrapolation of the presented approach towards quantification and integration of machine operator performance to other human-operated forest machinery needs to be investigated in subsequent studies

APA, Harvard, Vancouver, ISO, and other styles

15

Phillips, Russell Leslie. "Development of a reciprocating aerofoil wind energy harvester." Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/899.

Full text

Abstract:

Cross flow wind turbines are not unique. The performance of Savonius and Darrieus turbines is well documented. Both share the advantage of being able to accept fluid flow from any direction. The Savonius is drag based and hence has poor power output while the Darrieus is lift based. Due to the fact that the Darrieus has fixed blades the fluid flow through the rotor does not result in optimal lift being generated at all points in the rotation circle. A drawback of the Darrieus system is that it has to operate at a high tip-to wind-speed ratio to obtain reasonable performance with the fixed blades. Deviation from a small optimal range of tip speed ratios results in poor performance. The Darrieus also has poor starting torque. The research conducted in this project focused on overcoming the shortcomings of other turbines and developing an effective cross flow turbine capable of good performance. A number of different concepts were experimented with, however all were based on a symmetrical aerofoil presented to the actual relative airflow at an angle that would produce the highest lift force at all times. The lift force was then utilized to generate movement and to do work on an electrical generator. All concepts contemplated were researched to ascertain their appropriateness for the intended application. During development of the final experimental platform and after lodging of a provisional patent (RSA 2007/00927) it was ascertained that the design shared some similarities with an American patent 5503525 dated 28/4/1994. This patent employed complex electronic sensing and control equipment for control of blade angle. This was thought to be overly complex and costly, particularly for small scale wind energy generation applications and a simpler mechanical solution was sought in the design of the final experimental platform used in this project. The design of the mechanical control system was refined in an attempt to make it simpler, more durable and employ the least number of moving parts. Literature studies and patent searches conducted, suggested that the mechanical control system as developed for the final experimental platform was unique. The enormous variation in the power available from the wind at the different wind speeds likely to be encountered by the device necessitated some means of control. In high wind conditions control of the amount of wind power into the device was deemed to be the preferable means of control. A number of different concepts to achieve this were devised and tested. The final concept employed limited the tail angle deflection and hence the lift produced by the aerofoils. This resulted in a seamless “throttle” control allowing the device to be used in any wind strength by adjusting the control to a position that resulted in the device receiving a suitable amount of power from the wind. The outcome of performance tests conducted indicated that the device has the potential to be developed into a viable wind turbine for both small and large scale applications. The ability to control the power input from the wind to the machine from zero to a maximum is considered to be one of the most beneficial outcomes of this project and together with the quiet operation and low speed, are considered the main advantages of the device over existing wind turbine designs. The possibilities of using the device to compress air for energy storage are exciting avenues that warrant further research.

APA, Harvard, Vancouver, ISO, and other styles

16

Dimitriadis, Christos I. "The design of an improved efficiency lavender harvester." Thesis, Cranfield University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420670.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Moon, Jinyeong. "Electromagnetic energy harvester and self-powered embedded system." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106088.

Full text

Abstract:

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 289-293).
Energy harvesting offers an important design option for creating sensing and control elements without a requirement for custom wiring or batteries. The independent and care-free nature of energy harvesting enables monitoring devices to penetrate wider and deeper into our daily lives, making accommodation of fine sensing and control for condition-based maintenance ever more feasible. Finer granularity in sensing and control, which is the future of energy efficiency, alone is an immense benefit as it can reduce time and cost associated with a potential repair. Combined with condition-based maintenance, it can prevent potential down-time of a machine under monitoring. An exciting possibility creates a "self-powered" embedded system with an integrated energy harvester for electromechanical diagnosis. This non-intrusive energy harvester is designed to extract energy from magnetic fields around a power line of a load, in the manner of a current transformer. In contrast to the conventional usage of magnetic elements, such as transformers and inductors, the analysis on this "current transformer" reveals a critical result: for any given core for any particular application, power harvest is maximized when the core is permitted to saturate at an opportune time in the line cycle. The design of this integrated energy harvester is fully explored in the thesis, including: development of new models to incorporate a fully saturating magnetic core for simulation; designs of power electronics circuits for maximizing power harvest; and integration of the harvester into the embedded system as a practical power supply. The design of a self-powered and low-power embedded system, vibration assessment monitoring point with integrated recovery of energy (VAMPIRE), is discussed in depth in the thesis. The overall architecture of the embedded system is first presented, followed by designs of individual subsystems, the power package and the sensor package. In the power package, initialization, energy buffer, power interfaces, power regulation, and microcontroller design are explored. In the sensor package, power budget, sensors, data storages, storage management, wireless communication, and corresponding user interfaces are explored. Finally, impedance spectroscopy for an electromechanical load is discussed. Using the electrical and vibrational data that are nonintrusively collected from electromagnetically self-powered embedded system, structural issues of the load, i.e., changes in the stiffness of mounts and the imbalance of a shaft, can be clearly identified, making it feasible for this self-powered embedded system to be used for condition-based maintenance.
by Jinyeong Moon.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

18

Becker, Philipp [Verfasser], and Yiannos [Akademischer Betreuer] Manoli. "Effiziente Energieextraktion und -speicherung für piezoelektrische Energy Harvester." Freiburg : Universität, 2016. http://d-nb.info/1120020948/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Hedström, Gabriel. "Structural and tribological analysis of harvester crane joint." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69653.

Full text

Abstract:

Grease-lubricated journal bearings are widely used in heavy duty applications, such as construction equipment, agriculture- and forest machines. The main purpose of the grease-lubricated journal bearing is solely to create sustainable rotation of a given application. However, purpose seldom decides complexity of journal bearing design. Depending on application, parameters such as Load , Material and Lubrication immensely increase complexity of the design. Tribology is a highly interdisciplinary subject, which requires knowledge concerning physics, chemistry, metallurgy and solid mechanics. Tribological aspects of a design are frequently regarded as irrelevant. Tribological issues are commonly enlightened in combination with structural design weaknesses. The main aim of the thesis was to analyze two cylinder joints found in a Komatsu Forest 951 crane and establish root cause to the structural and tribological issues. Outline of the approach was divided into three main targets: 1. Investigate mechanical and tribological aspects of the crane design. 2. Understand how these aspects influence the life time of the bearings. 3. Summarize the analysis and suggest improvements based on the discovery. Fundamental structural and tribological design guidelines regarding grease-lubricated journal bearings have been presented in this thesis. Damaged components such as cylinders, pins and journal bearings have been examined at Komatsu Forest’s factory in Umeå. Further, a scanning electron microscopy study has been done at Luleå University of Technology, to determine predominant wear mechanisms in the harvester crane joints. A non-linear finite element model of the crane has been designed to represent pressure distribution in the contact between bearing and pin. The finite element analysis gives a good approximation of the contact but leaves room for further refinements. Temperatures, in the contacts, have not been identified and will be measured outside the time frame of the master’s thesis. Design changes, with respect to discovered structural and tribological issues have been suggested. The suggested improvements can potentially increase the life time of lift cylinders, pins and journal bearings.

APA, Harvard, Vancouver, ISO, and other styles

20

Rains, Glen Christopher. "Development of a whole-stalk sweet sorghum harvester." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/46063.

Full text

Abstract:

Sweet sorghum produces more carbohydrates and more biomass per unit land area than com in the Eastern U. S. Piedmont. An equipment system for harvesting and processing whole-stalk sweet sorghum is being developed, with the expectation that sweet sorghum can be commercialized as an ethanol feedstock.

A whole-stalk harvester was designed, constructed, and tested during the 1988 harvest season. The harvester captured a row of stalks between two counter rotating gathering belts, cut them at the base with a disk cutter (basecutter), and, at the rear of the machine, rotated the stalks 90Â° by capturing the stalk butts between to spring-loaded disks, called the stalk flipper. At a field speed of 6.7 km/h, the machine worked best when the flipper tangential velocity was 24 percent higher than the gathering belt Linear velocity, which was approximately (within six percent) equal to ground speed.

The harvester was pulled behind a tractor and powered with a universal joint drive line. Two computer software packages, Computer-Graphic Augmented Design and Manufacturing (CADAM) and Integrated Mechanisms Program (IMP), were used to design the hitch and drive line. Calculated angular accelerations in the 3-joint drive line were excessive during a right or left turn; consequently a constant velocity joint was used at the tractor PTO. The hitch was designed with three position settings. With the hitch in the Field 1 position, the harvester was offset sufficiently to capture a row with the gathering belts. In the travel position, the harvester trailed behind the tractor within the 2.4 m legal road width.

Master of Science

APA, Harvard, Vancouver, ISO, and other styles

21

Hedström, Samuel. "Design of energy storage application for forest harvester." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79856.

Full text

Abstract:

Komatsu Forest AB in Umeå saw an opportunity to increase performance during fast varying loads, e.g., when starting to feed after the felling cut, that proved more difficult to reach with their new line of stage V forest harvesters. It was believed that this issue was magnified as a result of new environmental regulations which limited their diesel engines' fuel injection quantity with low turbo boost pressure. It was in Komatsu Forest's interest to make comprehensive measurements of hydraulic and engine parameters in order to investigate what was limiting performance. This thesis includes a literature study into a number of viable options for storage types for a heavy hybrid vehicle with the purpose to recommend the best suited type for Komatsu's harvesters. It also includes extensive measurements made on a producing harvester where hydraulic and engine parameters as well as for example valve currents were logged and used as grounds in making the energy storage recommendation. With results from the measurements, the goal was to estimate how much energy is needed, how much energy can be stored and lastly to design an energy storage to supply additional power to increase performance. With successful measurements, it was possible to detect that approximately five kJ of energy with a maximum momentary power of 37 kW was sufficient to achieve a smoother first feeding. Furthermore, approximately 9-14 kJ of energy and between 0,3 and 0,5 l of hydraulic fluid was estimated as potential stored energy and volume from feeding stops of different sized trees plus an additional 3 kJ and 0,1 l of fluid from cutting stops. The best suited energy storage then proved to be an accumulator mounted on the P-line, which resulted in an appropriate accumulator volume of 4 l with an estimated pressure range of 250-280 bar.

APA, Harvard, Vancouver, ISO, and other styles

22

Horowitz, Stephen B. "Development of a MEMS-based acoustic energy harvester." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0008378.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Silva, Remo Macieira Figueiredo. "Avaliação econômica dos tratores florestais Harvester e Forwarder." Universidade Federal de Viçosa, 2015. http://www.locus.ufv.br/handle/123456789/7319.

Full text

Abstract:

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2016-03-09T11:53:15Z No. of bitstreams: 1 texto completo.pdf: 964563 bytes, checksum: 5ce1a842437d8851e896cda321870671 (MD5)
Made available in DSpace on 2016-03-09T11:53:15Z (GMT). No. of bitstreams: 1 texto completo.pdf: 964563 bytes, checksum: 5ce1a842437d8851e896cda321870671 (MD5) Previous issue date: 2015-02-24
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Neste trabalho objetivou-se avaliar economicamente os tratores florestais harvester e forwarder nas atividades de corte e extração de eucalipto. Foram utilizadas quatorze máquinas florestais, oito harvesters da marca Komatsu, modelo PC-228 utilizados na derrubada e processamento da madeira e seis forwarders da marca Komatsu, modelo 890.3 utilizados na extração da madeira. A base de dados utilizada foi fornecida por uma empresa florestal situada no estado de Minas Gerais, contendo todas as informações necessárias para o cálculo do custo operacional das máquinas, a análise de sensibilidade, o ponto de equilíbrio, o custo anual equivalente (CAE) e a taxa interna de retorno (TIR). O custo operacional foi obtido através do somatório dos custos fixos e variáveis. Para a análise de sensibilidade foi realizada uma variação de ± 20% (10% para mais e 10% para menos) dos elementos mais representativos do custo total da máquina. O ponto de equilíbrio foi utilizado para determinar a quantidade de horas mínimas que as máquinas deveriam trabalhar para viabilizar sua compra. O CAE foi utilizado para determinar o ponto de troca do trator e a TIR foi utilizada para determinar a rentabilidade da operação. Os resultados obtidos para o custo total médio do sistema de toras curtas constituído pelo módulo de colheita harvester e do forwarder foi de US$ 255,71 h -1 e US$ 199,82 h -1 respectivamente. A redução de 10% dos custos com manutenção e reparos, mão de obra, combustível e depreciação resultou em uma economia de 9,36% do harvester e de 9,06% do forwarder. Estes elementos representaram aproximadamente 88% do custo total do harvester e 90% do custo total do forwarder. Somente para os anos de 2010 e 2011 foi encontrado o ponto de equilíbrio para os tratores florestais, sendo que para esses anos somente o harvester apresentou horas de trabalho suficiente para viabilizar a sua compra. Não foi encontrado o ponto de troca do harvester e forwarder. Para ambas as máquinas avaliadas não foi encontrada a TIR.
In this work aimed to evaluate economically the harvester and the forwarder in activities cutting and extraction of eucalyptus. Were used fourteen forest machines, eight harvesters of brand Komatsu, model PC-228 used in overthrow and processing of wood and six forwarders of brand Komatsu, 890.3 model used in the extraction of timber. The database used was provided by a forestry company located in the state of Minas Gerais, containing all the information necessary for calculating the operating cost of the machines, the sensitivity analysis, the breakeven point, the equivalent annual cost (CAE) and the rate internal of return (TIR). The operating cost was obtained by the sum of the fixed and variable costs. To analysis sensitivity held was a variation ± 20% (10% for more and 10% for less) of the most representative elements of the total cost of the machine. The breakeven point was used to determine the amount of minimum hours that the machines should work to enable your purchase. The CAE was used to determine the change point tractor and the TIR was used to determine the profitability of the operation. The results obtained for the average total cost of system of short log compound by the harvester harvesting module and the forwarder was US $ 255.71 h -1 and US $ 199.82 h -1 respectively. The reduction of 10% of the costs for maintenance and repairs, labor, fuel and depreciation resulted in a saving of 9.36% of the harvester and of 9.06% of forwarder. These elements represented approximately 88% of the total cost of the harvester and 90% of the total cost of the forwarder. Only for the years 2010 and 2011 found the balance point for forest tractors, to those years only the harvester obtained hours of work enough to enable your purchase. Not was found the exchange point of harvester and forwarder. For both assessed machines was not found TIR.

APA, Harvard, Vancouver, ISO, and other styles

24

Topcuoglu, Ahmet. "Design and Testing of a Reciprocating Wind Harvester." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7971.

Full text

Abstract:

Renewable energy sources are vital to reduce dependence on fossil fuels that are harmful for the environment and release greenhouse gases causing global warming. Wind energy is a natural source of energy that is abundant in the environment. While wind turbines are most popular, convenient, and used to harvest energy at large scales, there have been recent studies focusing on harvesting energy from the wind for microdevices. Such micro wind energy harvesters can decrease dependence on batteries. In this study, a novel, framed flag micro wind harvester was designed and tested, and its behavior at three different wind speeds was experimentally examined in a wind tunnel. The main purpose of this study is to determine the geometric and wind speed conditions under which regular flapping occurs in the flag material. A high-speed camera was used to visualize the motion of the harvester at different wind speeds and at various parametric ratios of the flag material length to the frame length. The movies taken by the camera are analyzed using Image J software to find the flapping frequency, flapping angle, and the amplitude. Nondimensional parameters such as the Re number and St number also are calculated. This study finds that parametric ratios of 1.1 and 1.2 with the medium wind speed condition of 5 m/s are optimal flapping conditions. These optimal conditions would conveniently allow the use of piezoelectric material as the flag material in order to harvest energy. Further, an advantage of this novel design over previous designs is that the wind harvester naturally aligns with the wind direction and is thus omnidirectional.

APA, Harvard, Vancouver, ISO, and other styles

25

Lima, Carlos Magno de. "Desempenho de colhedoras semi-montadas de uma e de duas fileiras, para colheita mecanizada direta de milho." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11148/tde-16072008-122311/.

Full text

Abstract:

O objetivo do trabalho foi adaptar procedimentos de ensaio existentes para colhedoras autopropelidas e avaliar o desempenho de colhedoras semi-montadas de uma fileira (C1) e de duas fileiras (C2), em que os tratamentos foram as velocidades de deslocamento de 0,53 m s-1, 0,77 m s-1e 1,42 m s-1 (C1) e 0,59 m s-1, 0,85 m s-1 e 1,52 m s-1 (C2), em dois graus dede umidade de colheita (16 % e 22 %), utilizando rotação constante de 540 rpm na tomada de potência (TDP) para ambas as colhedoras. Para tanto foi desenvolvido um sistema para coletar toda a palha no seu ponto de saída, para quantificar as perdas de plataforma, separação e limpeza e trilha. Também foram realizadas análises de indicadores de qualidade da colheita, tais como impurezas nos grãos colhidos, danos mecânicos e falhas na germinação. O delineamento experimental empregado foi em blocos casualizados, em que as variáveis analisadas foram duas épocas de colheita e três velocidades de deslocamento, dispostos em esquema fatorial 2 x 3, com seis repetições. Os resultados demonstraram que não houve efeito dos tratamentos em relação às perdas totais de grãos na C1. Na C2 houve efeito significativo nos tratamentos de umidade e velocidade, em relação a todas as perdas, exceto às perdas de plataforma, apresentando melhor resultado quando a umidade dos grãos era de 16 % e a velocidade de deslocamento de 1,52 m s-1 e o pior desempenho, quando o grau de umidade dos grãos era de 22 % e a velocidade de deslocamento de 0,59 m s-1. No que tange ao indicador impurezas, a C1 apresentou efeito significativo apenas para o tratamento de velocidade, já na C2, não houve efeito dos tratamentos sobre a variável impureza. Quanto aos danos mecânicos, na C1 não houve diferenças significativas nos tratamentos testados. Na C2 houve efeito significativo para a interação umidade x velocidade. No parâmetro falhas de germinação, foi observado que na C1, houve efeito significativo do fator umidade, para o qual na condição de grãos com 16 %, foi aquela que apresentou as menores falhas. Na C2, houve efeito significativo do fator umidade, sendo que, o resultado observado na condição em que o grau de umidade dos grãos era de 16 % foi melhor do que em grãos com 22 %. Conclui-se que o procedimento adotado é efetivo para a avaliação do desempenho das colhedoras semi-montadas de milho e o sistema desenvolvido para a coleta de material é eficiente, porêm é exigente em mão-de-obra. Em relação às perdas, ambas as colhedoras apresentaram melhor desempenho quando o grau de umidade dos grãos no momento da colheita foi de 16 % e a operação de colheita realizada na maior velocidade (1,42 m s-1 para C1 e 1,52 m s-1 para C2). Em relação aos indicadores de qualidade dos grãos, ambas as colhedoras apresentaram melhor desempenho quando colheram com o menor grau de umidade (16 %) e nas menores velocidades de deslocamento.
The objective of the work was to adjust the methodology used for self propelled combines and evaluate the performance of semi-mounted harvesters of one row (C1) and two rows (C2). The treatments were the travel speed (0,53 m s-1, 0,77 m s-1e 1,42 m s-1 for C1 and 0,59 m s-1, 0,85 m s-1 and 1,52 m s-1 for C2), and grain moisture (16 % and 22 %), using 540 rpm in the tractor PTO for both harvesters. A system was developed to collect the whole residue (straw + grain losses) to quantify the head losses, and internal losses (thrashing, separation and cleaning). Analyses of crop quality indicators were also accomplished, such as grain impurities, mechanical damages and germination failures. The experiment was conducted as a randomized block design, and the variables were two harvesting times and three harvesting speeds, disposed in a 2 x 3 factorial with six replications. The results demonstrated that there was no effect of the treatments in relation to the total losses of grains in C1. In C2 there was significant effect in the grain moisture and speed treatments, in relation to all the losses, except for the platform losses, presenting better result when the grain moisture was of 16 % and speed of 1,52 m s-1, and the worst condition, when the grain moisture was of 22 % and the speed of 0,59 m s-1. In terms of quality, C1 presented significant effect for speed. On C2, there was no effect of treatments on impurities and on mechanical damages, in C1 there were no significant differences in the tested treatment levels. On C2 there was significant effect for the grain moisture x speed interaction. Related to germination, it was observed that on C1, there was significant effect of grain moisture, where 16 % presented the highest germination rate. In C2, there was significant effect of grain moisture and the 16 % level was better than 22 %. The conclusions are that the adjusted method is effective for testing harvesters performance, but it demands significant labor. In relation to the losses, both harvesters presented better performance when the grain moisture was at 16 % and harvesting at speed of 1,42 m s-1 for C1 and 1,52 m s-1 for C2. Both harvesters presented better quality results at grain moisture of 16 % and lower harvesting speeds.

APA, Harvard, Vancouver, ISO, and other styles

26

Emen, Seyfullah. "Power conditioning for MEMS-based waste vibrational energy harvester." Thesis, Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45848.

Full text

Abstract:

Approved for public release; distribution is unlimited
Increasing energy needs push industry to build more sustainable and efficient systems. One of the methods to achieve energy efficiency is to feed wasted energy generated by a system itself during operation back to the system. Vibrational energy is one of the most common ambient energy forms in mechanical systems and can be converted into electrical energy with the implementation of piezoelectric energy harvesters. What makes this possible is the piezoelectric effect that some crystals and ceramics with no inversion symmetry show. Piezoelectric materials generate a potential difference when a force is applied and deform under an electric field. Power electronics is used to turn this potential into a usable energy. The amount of power generated by a single piezoelectric energy harvester could be very low, but Microelectromechanical Systems (MEMS) technology makes it possible to have thousands of devices in a very small area. Previously, a MEMS-based piezoelectric harvester for military applications was designed, developed, and tested at NPS. In this thesis, methods to convert the AC voltage output of this device into a DC voltage were investigated to find an efficient method. Because of their higher power needs, multiple devices need to be connected to achieve required power levels for military applications. Microfabrication processes allow for building large number of such devices at the same time. This thesis also studies the possible connections for an array of devices. Connection geometry that will produce the maximum power output for a number of devices is proposed.

APA, Harvard, Vancouver, ISO, and other styles

27

Nordlie, Anders, and Staffan Till. "Head-Mounted Displays for Harvester Operators – A Pilot Study." Thesis, KTH, Maskinkonstruktion (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176265.

Full text

Abstract:

Harvester operators are handling large amounts of information while processing trees. Primarily by looking at the close environment, the trees, and the harvesting head, but also through the bucking display placed in front of the operator. Head-mounted displays have been under development since the 1960s but have yet to find any major applications where they excel outside military aircrafts despite numerous tries. This master thesis aims at evaluating the usability for head-mounted displays (HMDs) and augmented reality (AR) technology within forestry, by answering the research question: Are HMDs suited for displaying information in harvesters? What information is suitable to display in HMDs and how should it be displayed for best effect? A literature review about the current state of the art of HMDs and AR has been compiled which can be read independently. Qualitative user studies have been performed to map the current interactions of harvester operators by observation and interviews in the field. Interviews have been made with subject matter experts in relating fields. The insights gathered from the user studies led to three interface designs for bucking which were designed, prototyped and tested for usability in a harvester simulator. Ideas for other more immersive uses of the HMD were also designed. For bucking is assortment and species the most important information for the operators, contrary to how it is displayed today, where diameter and fed length is presented as the most significant information. Near machine navigation is a problem area which may be solved with AR. Operators participating in the test were positive towards the technology after testing. Our conclusion is that HMDs shows enough promise and performance to be evaluated further by tests in the field. Weight, brightness, and a non-occluding design are the most important properties for an HMD for harvesters.
Skördaroperatörer hanterar stora mängder information vid fällning och aptering. Främst genom att titta på omgivningen, träden och aggregatet men också via apteringsskärmen framför sig. Head-mounted Displays (HMDs) har varit under utveckling sedan 1960 talet men har hittat få tillämpningar utanför det militära flyget trots många studier. Detta examensarbete försöker utreda om HMDs och augmented reality (AR) är lämpliga tekniker för det mekaniserade skogsbruket genom att svara på frågorna: Är HMDs lämpliga för att visa information för skördaroperatörer? Vilken information skall då visas och hur ska den visas på bästa sätt? En litteraturstudie om HMDs och AR har genomförts och kan läsas fristående. Kvalitativa användarstudier har genomförts för att kartlägga skördaroperatörers arbete genom observationer och intervjuer. Intervjuer har även gjorts med experter inom närliggande områden. Från studierna har tre gränssnitt utvecklats och testats i en skördarsimulator. Idéer för AR gränssnitt har även de utformats. För aptering är sortiment och trädslag den viktigaste informationen att visas, i motsats till dagens gränssnitt där diameter och utmatad längd visas tydligast. Navigation i närheten av skördaren är ett problemområde som skulle kunna lösas med hjälp av AR. Operatörer i användartester har varit positiva till tekniken. Vår slutsats är att HMDs är tillräckligt lovande för fortsatta tester i fält för skördaroperatörer. Vikt, ljusstyrka och en design som inte skymmer sikten är de viktigaste faktorerna för en HMD för skördarbruk.

APA, Harvard, Vancouver, ISO, and other styles

28

Ayala, Garcia Ivo. "Autonomous operation of a tunable vibration based energy harvester." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/334326/.

Full text

Abstract:

Vibration-based energy harvesters transduce kinetic energy into electrical energy, which is then utilized to power small electronic systems, like wireless sensor nodes. Vibration-based harvesters are designed with high Q-factor to maximize their power generation capability; however, this results in low bandwidth of operation. Different tuning mechanisms have been previously presented, but none is integrated as an autonomous system. The work described in this thesis outlines the development of a tunable vibration-based energy harvester that adjusts its resonant frequency to coincide with the base frequency and it is powered exclusively by the harvester. This work builds upon an electromagnetic vibration-based energy harvester and a non-contact tuning mechanism previously developed in this research group. This thesis presents the integration of the different mechanical and electronic components required to operate the tuning mechanism with the lowest overhead power feasible; an optimal range of operation for the harvester, where the frequency bandwidth is maximized while the power used for tuning is minimized, is proposed. A closed loop frequency tuning system is presented that identifies when the base frequencies have changed and adjust the harvester resonant frequency in consequence, using the mathematical model of the harvester and the period difference between the harvester voltage and the base acceleration. Analysis of the operation of the harvester when exposed to a real application was performed. The system was modified to allow its operation under this condition. The optimization of the power extraction and conversion was also evaluated. The flexibility of the tunable harvester to adjust its resonant frequency increases by increasing the power available to perform this adjustment. Passive extraction and conversion is preferred due to the reduced overhead power compared to active conversion. The combined result of tuning and power extraction is a fully functional tunable energy harvester that operates autonomously. Its use as a power source for a wireless sensor node is demonstrated in this thesis.

APA, Harvard, Vancouver, ISO, and other styles

29

Pereira, Nayara Natacha de Jesus. "Desempenho no treinamento com simulador de realidade virtual Harvester." UFVJM, 2017. http://acervo.ufvjm.edu.br/jspui/handle/1/1458.

Full text

Abstract:

?rea de concentra??o: Manejo florestal e silvicultura.
Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-09-06T18:39:59Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) nayara_natacha_jesus_pereira.pdf: 1308237 bytes, checksum: c78cc1592d151bba2ecb1af0e1daee29 (MD5)
Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-09-18T16:59:14Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) nayara_natacha_jesus_pereira.pdf: 1308237 bytes, checksum: c78cc1592d151bba2ecb1af0e1daee29 (MD5)
Made available in DSpace on 2017-09-18T16:59:14Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) nayara_natacha_jesus_pereira.pdf: 1308237 bytes, checksum: c78cc1592d151bba2ecb1af0e1daee29 (MD5) Previous issue date: 2017
? cada vez mais crescente a demanda por profissionais capacitados para operar m?quinas com elevada tecnologia e valor comercial. A fim de resolver parte desse gargalo, o simulador de realidade virtual de m?quinas florestais est? entre as tecnologias mais utilizadas para treinamento com menor custo/benef?cio. Logo, definir e conhecer o perfil de um futuro operador frente ?s condi??es de trabalho do simulador possibilita maior chance de ?xito na execu??o das atividades de campo, com m?quinas de colheita florestal. Objetivou-se, com este trabalho avaliar o desempenho de operadores no treinamento com simulador de realidade virtual Harvester, considerando-se diferentes classes de idades, grau de escolaridade e categoria de habilita??o. Os dados s?o provenientes do Centro T?cnico de Forma??o de Operadores de M?quinas Florestais, situado no Campus JK da UFVJM, em Diamantina- MG. Foram avaliados 40 profissionais, sem experi?ncia na opera??o do Harvester. No decorrer dos treinamentos coletaram-se dados do desempenho dos profissionais, referentes apenas ao m?dulo V do software espec?fico (Simlog), por se tratar da fase que melhor caracteriza as principais atividades da m?quina. Com isso, os resultados evidenciaram que a diferen?a de tempo m?dio gasto no ciclo de opera??o do modulo V apresentou alta correla??o com a idade do operador, sendo diretamente proporcional ao aumento desta, ou seja, quanto maior a idade do operador em treinamento, maior a diferen?a entre o tempo m?dio gasto por ele em rela??o ? meta estabelecida. Para o teste de Kruskal-Wallis, a signific?ncia de 5% para Dif ? Tempo apontou diferen?a significativa apenas para os agrupamentos por habilita??o, mostrando que as diferentes categorias de habilita??o exercem influ?ncia sobre o tempo de execu??o das tarefas, sendo a categoria B a que apresentou menor Dif ? Tempo m?dio em rela??o ?s outras categorias. J? os agrupamentos por categoria de habilita??o e escolaridade n?o apresentam diferen?as significativas entre si.
Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Ci?ncia Florestal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017.
It is each time more growing the demand for skilled professionals to operate machines with high technology and commercial value. In order to address part of this bottleneck, the forest machine virtual reality simulator is among the most commonly used technologies for lower cost / benefit training. Therefore, defining and knowing the profile of a future operator in front of the working conditions of the simulator, allows a greater chance of success in the execution of the field activities, with forest harvesting machines. The objective of this work was to evaluate the performance of operators in the training with Harvester virtual reality simulator, considering different age classes, educational level and habilitation category. The data come from the Technical Center for the Training of Forest Machine Operators, located at JK Campus of UFVJM, in Diamantina-MG. 40 professionals were evaluated, with no experience in the operation of the Harvester. During the training, data were collected on the performance of the professionals, referring only to module V of the specific software (Simlog), because it is the phase that best characterizes the main activities of the machine. With this, the results showed that the mean time difference spent on the operating cycle of the V module showed a high correlation with the age of the operator, being directly proportional to the increase in age, that is, the higher the age of the operator in training, the higher the difference between the average time spent by him in relation to the established goal. For the Kruskal-Wallis test, the significance of 5% for Dif-Time showed a significant difference only for the groupings by habilitation, showing that the different categories of habilitation exert an influence on the time of execution of the tasks, being the category B that presented lower Dif - Mean time in relation to the other categories. not present significant differences between them.

APA, Harvard, Vancouver, ISO, and other styles

30

Kuiper, Sarah. "The combine harvester: defining a new food retail typology." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13126.

Full text

Abstract:

Includes bibliographical references.
The project developed out of a theoretical inquiry into the use of food as a design tool to facilitate urban regeneration. The need for change arises from the loss of public space due to corporate control over food and food retail taking place in privatised environments. This socio- spatial polarisation becomes visible when mapping the change from historic marketplace to supermarket. The two primary concerns which arise from this socio-spatial polarisation are that of food being viewed as a utilitarian commodity, which allows routine shopping to take place in a supermarket rather than a market, and an evacuation of the public realm with the disappearance of food from public marketplaces. Spatial and infrastructure analyses of existing food retail models within the existing food system in Cape Town identify an appropriate supermarket-market hybrid that facilitates the flows of people and produce while regenerating public space.

APA, Harvard, Vancouver, ISO, and other styles

31

Litak, Grzegorz, Andrzej Rysak, Marek Borowiec, Michael Scheffler, and Joachim Gier. "Vertical beam modal response in a broadband energy harvester." Sage, 2016. https://tud.qucosa.de/id/qucosa%3A35381.

Full text

Abstract:

We examined energy harvesting using a vertical composite laminate beam with an additional moving mass subjected to kinematic harmonic excitation. The gravity effect and the moving tip mass applied to the system cause considerable changes in effective spring-mass characteristics of the bending beam. Simultaneously, we observed dynamical beam damping by an additional degree of freedom and non-linear effects including friction between the moving mass and the beam structure. The experiments were performed on the beam excited kinematically by a shaker, while beam velocity measurements were made by a scanning laser vibrometer. We applied modal analysis in the limit of a fairly low excitation level. The selected modal vibrations are illustrated by corresponding output time series.

APA, Harvard, Vancouver, ISO, and other styles

32

Herrmann, Michael Philip. "Sexual Conflict and Chemical Communication in Hybridizing Harvester Ants." ScholarWorks @ UVM, 2016. http://scholarworks.uvm.edu/graddis/608.

Full text

Abstract:

Sexual conflict occurs when the fitness interests of males and females do not align with one another. The resolution of sexual conflict often depends on the level of control each sex has on the behavior in conflict. In Pogonomyrmex harvester ants with a genetically determined caste system, two separate lineages interbreed with one another during summer mating swarms. Diploid offspring sired by a single lineage develop into reproductive queens, while offspring sired by opposite-lineage parents develop into sterile workers. This results in sexual conflict, as males which mate with opposite lineage queens will produce only workers, resulting in no fitness benefit, while queens must mate with opposite-lineage males in order to obtain workers and survive. Despite these fitness differences, males do not discriminate between lineages prior to mating. One possible reason for the lack of male discrimination is that queens "mask" their identity cues, making discrimination difficult for males. In eusocial insects, identity cues are encoded by cuticular hydrocarbons (CHC’s) found on the exoskeleton of the insects. These cues contain information on the insect's reproductive status, sex, species, state, and nest membership. In addition to their communication functions, CHC’s also serve as desiccation-resistance molecules, preventing water from freely passing out of the cuticle. However, molecules that are best-suited for communication functions are poor desiccation resistance molecules, and molecules that are best-suited for waterproofing lack the diversity needed for communication; therefore, a tradeoff between these two functions is expected. In this dissertation, I explore sexual conflict in these ants and the chemical recognition cues that likely play a role in this conflict. To test for cryptic strategies in harvester ant mating swarms, I experimentally paired males and females from two interbreeding lineages of harvester ant with different fitness outcomes based on pairing, and measured the propensity to initiate copulation, pre-copulatory time, time in copula, and rate and amount of sperm transferred in each mating. Although females controlled copulation duration, males altered sperm transfer rates, resulting in no quantitative difference in total sperm transfer between lineages. To test for thermal constraints on the diversity and composition of cuticular hydrocarbon profiles, and changes in CHC profiles that occur in workers isolated from the queen, I surveyed the cuticular hydrocarbon profiles of a species complex of harvester ants. The CHC profiles of ants from more xeric environments showed evidence of constraints, while isolated workers differentiated from their queen-raised sisters, although not in queen-specific molecules. To test for queen identity masking and lack of discrimination ability in mating swarms, I tested for convergence in the CHC profiles of reproductives in two hybridizing lineages in response to the sexual conflict playing out in this species. Differences in CHC profiles were lost during the mating swarm, likely limiting male ability to discriminate between mates, limiting discrimination ability in mating swarms. To study the genetic regions that control CHC production, I created a physical linkage map of two of the interbreeding populations, and used that map to perform quantitative trait loci analysis on the cuticular hydrocarbon profile of recombinant males. One significant region associated with 13-methylnonacosane contained numerous odorant receptor genes, suggesting a link between that CHC production and the receptors that detect it, while a second region associated with n-pentacosane contained numerous genes that control expression levels. Overall, the genetic caste determination system in these ants leads to antagonistic coevolution between species. This coevolution is likely reinforced by the thermal constraints and exchange of recognition cues between species, lowering the ability of useful discrimination between lineages during mating swarms.

APA, Harvard, Vancouver, ISO, and other styles

33

Aljadiri, R. T. "Modelling and design of electrostatic based wind energy harvester." Thesis, Coventry University, 2014. http://curve.coventry.ac.uk/open/items/9ee6a6e1-bd1d-4717-b48d-ee48fefb4657/1.

Full text

Abstract:

Wireless sensor networks and portable electronic devices, such as mobile phones, media players, digital cameras and iPods, require local electric power supplies. Although these devices are operational all the time, they consume just a few milli-or micro-watts. This means energy harvesting from the environment is an attractive option for powering these devices. Mechanical energy harvesters can use electromagnet, electrostatic or piezoelectric approaches. Of these, electrostatic devices are found to be the most suitable approach for harvesting mechanical energy since they are compact, sensitive to low level mechanical energy, easier to integrate in small scale systems, not requiring smart materials, simple to fabricate, inexpensive and simply structured using less circuitry. Most of electrostatic harvesters proposed in previous studies use mechanical vibration. However, only a few studies have investigated harvesting rotational mechanical energy. The objective of this thesis is to investigate the possibility of harvesting rotational mechanical energy from wind using the electrostatic approach. The proposal involves capturing wind energy using a micro wind turbine then converting it into usable electrical energy. This work first considers general design considerations and the design procedure that must be followed to construct a suitable electrostatic based wind energy harvester. Second, it describes the operating principles of various parts needed to design a novel efficient electrostatic harvesting system. The new harvester consists of a micro wind turbine, a gearbox, a multi-pole variable capacitor or capacitor array, an LC to LC energy transfer circuit, a capacitance sensing system and a microcontroller. The harvesting process has three main steps. First, wind energy is captured and converted into mechanical power using the micro wind turbine. Second, mechanical power is converted into electrical power using the variable capacitor in three phases: pre-charge, harvest and reset. Third, the electrical energy is processed and stored in a Lithium ion battery. The proposed harvester was simulated using Matlab/Simulink to study energy transfer throughout the three energy harvesting phases. Energy analysis was then carried out to study the effect of varying the structure of the multi-pole capacitor on the amount of harvested energy. Results from the simulation for capacitance variation from 2.5 nF to 0.6 nF indicated that an eight-pole variable capacitor can produce 29.43 μJ/sec at a wind speed of 10 m/sec, while a capacitor array of the same capacitance variation with 10 capacitors in the array can produce 295 μJ/sec at a wind speed of 10 m/sec. The results of experiments were carried out to test wind harvesting using a two-pole capacitor proved that the proposed harvester is capable of powering an RF transmitter to transmit wind speed information wirelessly.

APA, Harvard, Vancouver, ISO, and other styles

34

Yang, Yuechen. "Optimization of a vibrations based electromagnetic MEMS energy harvester." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122997.

Full text

Abstract:

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 93).
This thesis includes the design and fabrication of an electromagnetic energy harvester on Silicon and MP35N metal alloy. The mechanical harvester is a spring-mass-damper system that converts mechanical energy into electrical energy. This project resulted in the development of an optimized design flow for vibration EM energy harvesters utilizing a traversing mass. The harvester, which is the focus of this project, interfaces with a custom built control circuit, which is the interface between the electromagnetic harvester and the power bank. The goal of the project is to optimize the electromagnetic harvester and explore designs for practical implementation. The initial Silicon harvester design results in a matched-load power output of 2.2 mW, and a matched-load power-output density of 1.23 mW/cm3 at 1.1 g with a resonance frequency of 76.3 Hz. Using the optimization scheme developed from the Silicon harvester, the MP35N harvester achieves a matched-load power output of 1.2 mW, and a power density of 1.03 mW/cm3 while drastically decreasing the device footprint. The MP35N harvester is robust enough to withstand drops during assembly process and large transient accelerations. The improved durability also enables the installation of back irons, which shows promise of further improving the power output by bringing the raw output power to 1.9 mW at resonance and with matched load.
by Yuechen Yang.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

APA, Harvard, Vancouver, ISO, and other styles

35

Masumdar, Salim. "Vibration-based electromagnetic energy harvester for low-frequency road traffic." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10638807.

Full text

Abstract:

In recent times, wireless sensor network (WSN) has played an important role for applications in the biomedical, commercial, and military fields. One of the applications is in intelligent transportation system (ITS), which uses sensors placed under the roads to detect vehicles. Progress in the field of Micro-Electro-Mechanical System (MEMS) has made it possible to make sensors that are small and easy to install, but operate on batteries which need to be replaced on a regular basis. For this reason, an alternative supply of power is necessary to run the sensors more effectively.

This thesis project proposes an idea in which the road vibrations can be used to harvest energy, which will further be used to supply power to the sensors. The concept of electromagnetic induction is applied to convert traffic-induced road vibrations into electrical energy. This project is more focused on getting maximum output from low vibrations by making use of a repulsive stack arrangement of magnets rather than using a single magnet while keeping the size of the energy harvester small. The simulation model of the harvester was designed using Simulink and COMSOL software.

The simulation model takes into consideration the vibration data and gives the output voltage generated by the harvester model. Output voltages for road vibrations occurring at different frequencies were tested. Using a repulsive stack approach provided an increase in output voltage compared to a single magnet approach.

APA, Harvard, Vancouver, ISO, and other styles

36

Ooi, Beng Lee. "Optimisation and frequency tuning concepts for a vibration energy harvester." Thesis, University of Hull, 2010. http://hydra.hull.ac.uk/resources/hull:4472.

Full text

Abstract:

With current electronic designs becoming more versatile and mobile, applications that were wired and bulky before have now seen a great reduction in size and increase in portability. However, the issue is that the scaling down in size and cost of electronics has far outpaced the scaling up of energy density in batteries. Therefore, a great deal of research has been carried out to search for alternative power sources that can replace or enhance the conventional battery. Energy harvesting (also known as energy scavenging) is the process whereby ambient energy is captured and stored. The ambient energy here refers to energy that is pre-existing in nature, and is self-regenerating and has extended life time from a battery. After reviewing many possible energy scavenging methods, the conversion of ambient vibrations to electricity is chosen as a method for further research. There are plenty of different methods to transform ambient vibration to electricity, but in this research only piezoelectric and electromagnetic conversions are pursued. In order to harvest the most energy with the harvesting device, the harvester’s fundamental mode must be excited. However, this is not always possible due to fluctuations in the frequency of the vibration source. By being able to change the natural frequencies of the device, the harvester could be more effective in capturing ambient energy. In this thesis, the behaviour of the various types of energy sources is studied and the obtained information is later used to generate a vibration signal for subsequent simulation and experiments. A converter based on a piezoelectric bimorph is investigated. The resultant outputs from the design are compared to the model and the analysis is presented. The mechanical strain distributions on the beam’s surface for five different geometric structures are compared and discussed. This is followed by a discussion of the feasibility of improving the strain distribution by changing the beam’s depth (height) along the cantilever beam length. Lastly, a novel frequency tuning method, which involves applying a different effective electrical damping in different quadrants of the oscillating cycle, is proposed. The results of this analysis are presented, along with experimental results that indicate that the behaviour of the system can be changed over a limited range by changing the effective electrical damping during the oscillation cycle.

APA, Harvard, Vancouver, ISO, and other styles

37

Du, Toit Noël Eduard. "Modeling and design of a MEMS piezoelectric vibration energy harvester." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32450.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.
Includes bibliographical references (p. 181-195).
The modeling and design of MEMS-scale piezoelectric-based vibration energy harvesters (MPVEH) are presented. The work is motivated by the need for pervasive and limitless power for wireless sensor nodes that have application in structural health monitoring, homeland security, and infrastructure monitoring. A review of prior milli- to micro-scale harvesters is provided. Common ambient low-level vibration sources are characterized experimentally. Coupled with a dissipative system model and a mechanical damping investigation, a new scale-dependent operating frequency selection scheme is presented. Coupled electromechanical structural models are developed, based on the linear piezoelectric constitutive description, to predict uni-morph and bi-morph cantilever beam harvester performance. Piezoelectric coupling non-intuitively cancels from the power prediction under power-optimal operating conditions, although the voltage and current are still dependent on this property. Piezoelectric material selection and mode of operation ([3-1] vs. [3-3]) therefore have little effect on the maximum power extracted. The model is verified for resonance and off-resonance operation by comparison to new experimental results for a macro-scale harvester. Excellent correlation is obtained away from resonances in the small-strain linear piezoelectric regime. The model consistently underpredicts the response at resonances due to the known non-linear piezoelectric constitutive response (higher strain regime). Applying the model, an optimized single prototype bi-morph MPVEH is designed concurrently with a microfabrication scheme.
(cont.) A low-level (2.5 m/s²), low-frequency (150 Hz) vibration source is targeted for anti-resonance operation, and a power density of 313 [mu]W/cm³ and peak-to-peak voltage of 0.38 V are predicted per harvester. Methodologies for the scalar analysis and optimization of uni-morph and bi-morph harvesters are developed, as well as a scheme for chip-level assembly of harvester clusters to meet different node power requirements.
by Noël Eduard du Toit.
S.M.

APA, Harvard, Vancouver, ISO, and other styles

38

Dhayal, 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 text

Abstract:

This work presents an investigation of a piezoelectric sensor based energy harvesting system, which collects energy from the surrounding environment. Increasing costs and scarcity of fossil fuels is a great concern today for supplying power to electronic devices. Furthermore, generating electricity by ordinary methods is a complicated process. Disposal of chemical batteries and cables is polluting the nature every day. Due to these reasons, research on energy harvesting from renewable resources has become mandatory in order to achieve improved methods and strategies of generating and storing electricity. Many low power devices being used in everyday life can be powered by harvesting energy from natural energy resources. Power overhead and power energy efficiency is of prime concern in electronic circuits. In this work, an energy harvester is modeled and simulated in Simscape™ for the functional analysis and comparison of achieved outcomes with previous work. Results demonstrate that the harvester produces power in the 0 μW to 100 μW range, which is an adequate amount to provide supply to low power devices. Power efficiency calculations also demonstrate that the implemented harvester is capable of generating and storing power for low power pervasive applications.

APA, Harvard, Vancouver, ISO, and other styles

39

Germer, M., U. Marschner, and A. B. Flatau. "Design and experimental verification of an improved magnetostrictive energy harvester." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35134.

Full text

Abstract:

This paper summarizes and extends the modeling state of the art of magnetostrictive energy harvesters with a focus on the pick-up coil design. The harvester is a one-sided clamped galfenol unimorph loaded with two brass pieces each containing a permanent magnet to create a biased magnetic field. Measurements on different pick-up coils were conducted and compared with results from an analytic model. Resistance, mass and inductance were formulated and proved by measurements. Both the length for a constant number of turns and the number of turns for a constant coil length were also modeled and varied. The results confirm that the output voltage depends on the coil length for a constant number of turns and is higher for smaller coils. In contrast to a uniform magnetic field, the maximal output voltage is gained if the coil is placed not directly at but near the fixation. Two effects explain this behavior: Due to the permanent magnet next to the fixation, the magnetic force is higher and orientates the magnetic domains stronger. The clamping locally increases the stress and forces the magnetic domains to orientate, too. For that reason the material is stiffer and therefore the strain smaller. The tradeoff between a higher induced voltage in the coil and an increasing inductance and resistance for every additional turn are presented together with an experimental validation of the models. Based on the results guidelines are given to design an optimal coil which maximizes the output power for a given unimorph.

APA, Harvard, Vancouver, ISO, and other styles

40

Zaveri, Jainish K. "Asic Design of RF Energy Harvester Using 0.13UM CMOS Technology." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1940.

Full text

Abstract:

Recent advances in wireless sensor nodes, data acquisition devices, wearable and implantable medical devices have paved way for low power (sub 50uW) devices. These devices generally use small solid state or thin film batteries for power supply which need replacement or need to be removed for charging. RF energy harvesting technology can be used to charge these batteries without the need to remove the battery from the device, thus providing a sustainable power supply. In other cases, a battery can become unnecessary altogether. This enables us to deploy wireless network nodes in places where regular physical access to the nodes is difficult or cumbersome. This thesis proposes a design of an RF energy harvesting device able to charge commercially available thin film or solid-state batteries. The energy harvesting amplifier circuit is designed in Global Foundry 0.13um CMOS technology using Cadence integrated circuit design tools. This Application Specific Integrated Circuit (ASIC) is intended to have as small a footprint as possible so that it can be easily integrated with the above-mentioned devices. While a dedicated RF power source is a direct solution to provide sustainable power to the harvesting circuit, harvesting ambient RF power from TV and UHF cellular frequencies increases the possibilities of where the harvesting device can be placed. The biggest challenge for RF energy harvesting technology is the availability of adequate amount of RF power. This thesis also presents a survey of available RF power at various ultra-high frequencies in San Luis Obispo, CA.The idea is to determine the frequency band which can provide maximum RF power for harvesting and design a harvester for that frequency band.

APA, Harvard, Vancouver, ISO, and other styles

41

ZHANG, FU-XIANG, and 張福祥. "Design of a taro harvester." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/17865490867106439563.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

ZHONG, YOU-DA, and 鍾侑達. "Design of a cabbage harvester." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/84318127607518906578.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Hsieh, Ching-Yu, and 謝慶裕. "Development of Pineapple Prototype Harvester." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5bnd43.

Full text

Abstract:

碩士
國立嘉義大學
生物機電工程學系研究所
106
Abstract This study developed a seated pineapple harvesting dedicated machine attached to a farm concentrated Handling truck.Design and R&D is based on the design concept of “Artificial Mining Machinery Collection” The main structural design research and development is focused on the farm concentrated Handling truck and harvesting platform department.The diesel engine wheel transmission is used as the vehicle body power source, and the harvesting department is designed to use the hydraulic system as the lifting power to adjust the height of the harvesting position.The harvesting department is designed and installed at the rear end of the harvesting machine, equipped with two harvesting laborers, and can harvest four lines at a time for each operation.The artificially harvested pineapple fruit is immediately put in the basket. After the full set of each basket, the oil pressure system is used to control the lifting handle to lift and lift to the scoop bucket platform, and the roller conveyor is pushed into the bucket to achieve labor-saving delivery Features. The test results show that the pineapple harvester harvested in this study does not need to bear the weight and manual handling of pineapple, and can largely replace the heavy harvesting methods of traditionally harvested pineapple, and can avoid the collision damage of pineapple fruit during operations. Since artificial harvesting increases with the harvest time, physical fatigue and physical exertion also increase. In order to improve the efficiency of harvesting and the willingness of young people to stay in agriculture, the collection basket and hydraulic lift system are designed to harvest, harvest, and transport the harvester. The established operation mode shows that labor saving and efficiency are obvious. After the farmers use the mechanized operation habits, they will greatly reduce their labor demand and improve their harvesting efficiency. They are expected to increase the income of the farmers and assist in the creation of the pineapple industry's ability to compete in the international market. Keywords: Pineapple, Harvester, Ride Style

APA, Harvard, Vancouver, ISO, and other styles

44

Sriramdas, Rammohan. "Vibrational Energy Harvesting : Design, Performance and Scaling Analysis." Thesis, 2016. http://etd.iisc.ernet.in/2005/3814.

Full text

Abstract:

Low-power requirements of contemporary sensing technology attract research on alternate power sources that can replace batteries. Energy harvesters function as power sources for sensors and other low-power devices by transducing the ambient energy into usable electrical form. Energy harvesters absorbing the ambient vibrations that have potential to deliver uninterrupted power to sensing nodes installed in remote and vibration rich environments motivate the research in vibrational energy harvesting. Piezoelectric bimorphs have been demonstrating a pre-eminence in converting the mechanical energy in ambient vibrations into electrical energy. Improving the performance of these harvesters is pivotal as the energy in ambient vibrations is innately low. The present work is organized in three major sections: firstly, audit of the energy available in a vibrating source and design for effective transfer of the energy to harvesters, secondly, design of vibration energy harvesters with a focus to enhance their performance, and lastly, identification of key performance metrics influencing conversion efficiencies and scaling analysis for MEMS harvesters. Typical vibration levels in stationary installations such as surfaces of blowers and ducts, and in mobile platforms such as light and heavy transport vehicles, are determined by measuring the acceleration signal. The frequency content in the signal is determined from the Fast Fourier Transform. A method of determining the energy associated with the vibrating source and the associated power using power spectral density of the signal is proposed. Power requirements of typical sensing nodes are listed with an intent to determine the adequacy of energy harvesting. Effective transfer of energy from a given vibration source is addressed through the concept of dynamic vibration absorption, which is a passive technique for suppressing unintended vibrations. Optimal absorption of energy from a vibration source entails the determination of absorber parameters such as resonant frequency and damping. We propose an iterative method to obtain these parameters for a generic case of large number of identical vibration absorbers resembling harvesters by minimizing the total energy absorbed by the system. The proposed method is verified by analysing the response of a set of cantilever absorber beams placed on a vibrating cantilever plate. We find, using our method, the values of the absorber mass, resonant frequency and damping of the absorber at which significant amount of energy supplied to the system flows into the absorber, a scenario which is favourable for energy harvesting. We emphasize through our work that monitoring energies in the system and optimizing their flow is both rational and vital for designing multiple harvesters that absorb energy from a given vibration source optimally. Enhancing the performance of piezoelectric energy harvesters through a multilayer and, in particular, a multistep configuration is presented. Partial coverage of piezoelectric material in steps along the length of a cantilever beam results in a multistep piezoelectric energy harvester. We find that the power generated by a multistep beam is almost twice of that generated by a multilayer harvester made out of the same volume of polyviny-lidine fluoride (PVDF), further corroborated experimentally. Improvements observed in the power generated prove to be a boon for weakly coupled, low pro le, piezoelectric materials. Thus, in spite of the weak piezoelectric coupling observed in PVDF, its energy harvesting capability can be improved significantly by using it in a multistep piezoelectric beam configuration. Besides, the effect of piezoelectric step length and thickness in a piezoelectric unimorph harvester and performance metrics such as piezoelectric coupling factor and efficiency of conversion are presented. Modeling of a hybrid energy harvester composed of piezoelectric and electromagnetic mechanisms of energy conversion motivated by the need to determine the contribution of each domain to the power generated by the harvester is presented, particularly, when multiple domains exist in a single harvester. Two exclusive schemes of energy transduction are represented using equivalent circuits, which allow modeling any additional transduction scheme employed in the hybrid harvester with relative ease. Furthermore, a method of determining optimal loads in the respective domains using the equivalent circuit of the hybrid harvester is presented. Four different hybrid energy harvesters were fabricated and evaluated for their performance in comparison with that estimated from the proposed models. Additionally, scaling laws for hybrid energy harvesters are presented. The power developed by both piezoelectric and electromagnetic domains is observed to decrease with width and length cubed. Power indices and figures of merit in a hybrid harvester are proposed and are used to estimate the efficiencies of the four fabricated hybrid harvesters. The important design parameters for micro scale harvesting are identified by performing scaling analysis on MEMS piezoelectric harvesters. Performance of energy harvesters is directly related to the harvester attributes, viz., size, material, and end-mass. Depending on the contribution from each attribute, the power developed by MEMS harvesters can vary widely. A novel method of delineating the power developed by a harvester using five exclusive factors representing scaling, composition, inertia, material, and power (SCIMP) factors is presented. Although the proposed method can be extended to bi-morph and multilayer harvesters, in the present work, we elucidate it by applying it to a MEMS unimorph. We also present a unique coupling factor that ensures maximum power factor in a harvester. As any tiny increment in the power generated would considerably improve the power densities of MEMS harvesters, we focus on enhancing the power developed by maximizing each of the five exclusive factors irrespective of material and size. Furthermore, we demonstrate the competence of the proposed method by applying it on nine different MEMS harvesters reported in the literature. Considering the close match between the reported and predicted performance, we emphasize that monitoring the proposed factors is sufficient to attain the best performance from a harvester.

APA, Harvard, Vancouver, ISO, and other styles

45

McGehee, Clark Coleman. "Dynamics of an Ocean Energy Harvester." Diss., 2013. http://hdl.handle.net/10161/8223.

Full text

Abstract:

Ocean-based wireless sensor networks serve many important purposes ranging from tsunami early warning to anti-submarine warfare. Developing energy harvesting devices that make these networks self-sufficient allows for reduced maintenance cost and greater reliability. Many methods exist for powering these devices, including internal batteries, photovoltaic cells and thermoelectric generators, but the most reliable method, if realized, would be to power these devices with an internal kinetic energy harvester capable of reliably converting wave motion into electrical power. Designing such a device is a challenge, as the ocean excitation environment is characterized by shifting frequencies across a relatively wide bandwidth. As such, traditional linear kinetic energy harvesting designs are not capable of reliably generating power. Instead, a nonlinear device is better suited to the job, and the task of this dissertation is to investigate the behaviors of devices that could be employed to this end.

This dissertation is motivated by the design and analysis of an ocean energy harvester based on a horizontal pendulum system. In the course of investigating the dynamics of this system, several discoveries related to other energy harvesting systems were made and are also reported herein. It is found that the most reliable method of characterizing the behaviors of a nonlinear energy harvesting device in the characteristically random forcing environment of the ocean is to utilize statistical methods to inform the design of a functional device. It is discovered that a horizontal pendulum-like device could serve as an energy harvesting mechanism in small self-

sufficient wireless sensor buoys if properly designed and if the proper transduction mechanisms are designed and employed to convert the mechanical energy of the device into electrical power.

Dissertation

APA, Harvard, Vancouver, ISO, and other styles

46

Liu, Nai-Ren, and 劉乃仁. "A shear mode piezoelectric energy harvester." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/85812008437132659086.

Full text

Abstract:

碩士
國立中興大學
精密工程學系所
98
A shear mode piezoelectric energy harvester for harnessing energy from flow-induced vibration is developed. It converts flow energy into electrical energy by piezoelectric conversion with oscillation of a piezoelectric beam. A finite element model is developed in order to estimate the generated voltage of the piezoelectric beam. Prototypes of the energy harvester are fabricated and tested. Experimental results show that an open circuit output voltage of 72mVpp are generated when the excitation pressure oscillates with an amplitude of 20.80 kPa and a frequency of about 45 Hz. The solution of the generated voltage based on the finite element model is compared with the experiments. Based on the finite element model, the effects of the piezoelectric beam dimensions, the fluid pressure applied to the harvester and types of piezoelectric beam on the output voltage of the harvester can be investigated.

APA, Harvard, Vancouver, ISO, and other styles

47

Pritzl, Patrick Joseph. "Reduced energy forage harvester conveying systems." 1990. http://catalog.hathitrust.org/api/volumes/oclc/23706846.html.

Full text

Abstract:

Thesis (M.S.)--University of Wisconsin--Madison, 1990.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 70-72).

APA, Harvard, Vancouver, ISO, and other styles

48

Wei, Mao-Quan, and 魏懋全. "High Sensitivity of Energy Harvester Research." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/36666458438591796134.

Full text

Abstract:

碩士
國立暨南國際大學
電機工程學系
100
In this study, we report a reproducible, highly scalable, and highly sensitive broadband 1Hz~1kHz vibrated energy harvester with innovated self-alternation magnetic-flux (SAMF) and 3D-coils designs. High sensitivity of 2~6 mV/coil at very wide frequency range of 1Hz ~ 1kHz than previous reports (~1 mV/coil), small magnet volume of 132 mm3, and the very fast transient time of < 0.25 sec are achieved due to innovated SAMF. Meanwhile, we also demonstrated 3D-colis stack-ability for output voltage enhancement. This vibrated energy harvester thus offers high potential for several kinds of applications, such as human motion, automotive etc..

APA, Harvard, Vancouver, ISO, and other styles

49

Chen, Chuan-wei, and 陳雋為. "Parallel Operation of the Piezoelectric Energy Harvester." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66251111389135246536.

Full text

Abstract:

碩士
逢甲大學
電機工程所
98
This thesis investigates a technique for a piezoelectric generator system using the synchronized switch harvesting on inductor (SSHI) electronic interface. Piezoelectric materials can convert mechanical energy into electrical energy through direct piezoelectric effect. However, the electricity generated by piezoelectric generator would reduce when the piezoelectric materials are parallel-connected. To use the electronic interface structures, the bridge-rectifier or the SSHI, harvest the energy from the piezoelectric generator. Compared with the harvested energy from piezoelectric materials immediately, these electronic interface structures showed an increase definitely. And the structure of the SSHI is better than the bridge-rectifier. This thesis then applies the methods of Taguchi parameter design for the SSHI structure. It enhances the generator power and efficiency. The designed SSHI structure is utilized to harvest energy of piezoelectric brick, and the results of measurement verify the feasibility of this structure in the experiment.

APA, Harvard, Vancouver, ISO, and other styles

50

Almeida, Gonçalo Fernandes Ferreira de. "Power management circuit for piezoelectric energy harvester." Master's thesis, 2020. http://hdl.handle.net/1822/70163.

Full text

Abstract:

Dissertação de mestrado em Biomedical Engineering (área de especialização em Medical Electronics)
The master dissertation presents a study in the area of mixed analogue/digital signals of CMOS circuits integrating a power management circuit for energy harvester. Focusing on the development of a current and voltage referencing circuits, and a current starved voltage-controlled oscillator addressing low power demands. The circuit components are designed based on 130nm CMOS technology. A physical layout of all the intervenient components described in this project report was developed for fabrication purposes. The choice of this technology adjusts to the research requirements benefiting its robustness, costliness, and performance. The developed work comprises the necessary steps to perform an ASIC project, comprising on circuit schematic optimization and simulation, physical layout design, parasitic extraction, validation of the physical layout, integrated circuit fabrication. A robust voltage reference is capable of outputting a stable 258.35mV with a line sensitivity of 0.49%/V in response to a 1-3.2V voltage supply, also presenting an excellent power supply rejection ratio of 58dB at 100Hz. An implemented current starved voltage-controlled oscillator generates an average periodic signal at a frequency of 84.81kHz. This circuit shows the capability to produce a local clock time to release the stored scavenged from the energy harvester to an application. A current reference can generate a 41.5nA at 2V of power supply, with a 0.19nA/oC. Although the temperature coefficient is not very useful, a self-biased current and voltage reference shows the capability to provide bias for other circuits within the integrated circuit.
Esta dissertação de mestrado apresenta um estudo na área CMOS em circuitos analógicos / digitais inseridos num circuito integrado responsável por estabelecer interface entre o transdutor e a sua aplicação. O design de circuitos de referência (tensão e corrente) e a implementação de um oscilador limitado pela tensão de referência são descritos nesta dissertação. Estes circuitos assumem uma função crucial para o objetivo primordial do projeto. A tecnologia CMOS empregada foi de 130nm com um software EDA do qual foi realizado o layout. A tecnologia escolhida foi um dos requisitos impostos pelo projeto. O trabalho desenvolvido compreendeu todas as etapas necessárias para desenvolver um projeto de ASIC. Deu-se primazia a simulação dos circuitos, a otimização, o layout físico, a extração de parasitas, a validação do layout físico e a fabricação do circuito integrado. Quando se aplicou uma fonte de tensão de 1-3.2V a um circuito de tensão de referência, este gerou uma tensão constante de 258mV, com uma sensibilidade de 0.49%/V. Este circuito apresentou um PSRR de 58dB, a 100Hz. O oscilador produziu um sinal periódico de 84.81kHz e teve a capacidade de controlar o switch responsável pelo armazenamento da tensão extraída do piezoelétrico para um condensador. A corrente de referência foi capaz de gerar 41.5nA, a 2V de fonte de alimentação, com 0.19nA/oC. Embora, os coeficientes de temperatura nos circuitos de referência não tenham sido satisfatórios, estes apresentaram capacidade em polarizar outros circuitos no chip produzido.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Harvester'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles