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Ahmadi, Mehdi. "Energy Harvesting Wireless Piezoelectric Resonant Force Sensor". Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc407829/.
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The piezoelectric energy harvester has become a new powering option for some low-power electronic devices such as MEMS (Micro Electrical Mechanical System) sensors. Piezoelectric materials can collect the ambient vibrations energy and convert it to electrical energy. This thesis is intended to demonstrate the behavior of a piezoelectric energy harvester system at elevated temperature from room temperature up to 82°C, and compares the system’s performance using different piezoelectric materials. The systems are structured with a Lead Magnesium Niobate-Lead Titanate (PMN-PT) single crystal patch bonded to an aluminum cantilever beam, Lead Indium Niobate-Lead Magnesium Niobate-Lead Titanate (PIN-PMN-PT) single crystal patch bonded to an aluminum cantilever beam and a bimorph cantilever beam which is made of Lead Zirconate Titanate (PZT). The results of this experimental study show the effects of the temperature on the operation frequency and output power of the piezoelectric energy harvesting system. The harvested electrical energy has been stored in storage circuits including a battery. Then, the stored energy has been used to power up the other part of the system, a wireless resonator force sensor, which uses frequency conversion techniques to convert the sensor’s ultrasonic signal to a microwave signal in order to transmit the signal wirelessly.
2
Wallace, Christopher James. "The low energy phenomenology of a dark force". Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11240/.
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This thesis investigates an area of beyond the Standard Model (BSM) phenomenology associated with the presence of additional light, “weakly interacting slim particles” (WISPs). Particular attention is given to the hidden photon, the gauge boson associated with an additional U(1) gauge group that mixes kinetically with hypercharge. The theoretical foundation of the interactions studied lies in effective field theory, and the first part of the thesis investigates a so-far untested aspect of effective theories, namely effective non-locality in particle propagation. There are no observable effects of hidden photons if they are massless. We investigate the impact on experimental signatures in the case that the hidden photon gets its mass during compactification from a higher dimensional theory. WISPs make good dark matter candidates, and are especially compelling in light of the lack of observation of heavy WIMP (“weakly interacting massive particle”) dark matter. Nonetheless, it is shown that if WIMP dark matter is composed of a Dirac fermion that couples to the SM only through a pseudoscalar, indirect detection may be our only experimental window, and that it may already be appearing as a gamma ray excess at the Galactic Centre. There is considerable interest in dark matter searches at beam dump facilities, in particular for light dark matter coupled through a similarly light mediator particle. We investigate this set up in the context of the E613 beam dump experiment. Owing to the light mediator, the low-Q^2 kinematic region of deep inelastic scattering is especially important. We present a new treatment of dark particle scattering in this region via a light vector mediator (such as a hidden photon), and find that it enhances constraints.
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Schimann, Hubert C. R. "Force and Energy Measurement of Bubble-Particle Detachment". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9963.
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Possibilities for increasing the upper limit of floatable particle sizs in the froth flotation process have been examined since the early beginnings of mineral flotation. The economic implications of such an incresae are far ranging; from decreased grinding costs and increased recoveries to simplified flow-sheet design and increased throughput, all leading to increased revenue. Bubble-particle detachment has been studied to better understand the factors influencing the strength of attachment and the energies involved. Direct measurements of bubble particle detachment were performed using a hanging balance apparatus (KSV Sigma 70 tensiometer) and using a submerged hydrophobic plate in water. Three experiments were used; direct force measurement of bubble-particle detachment, detachment force and energy of a bubble from a submerged hydrophobic plate, and detachment force and energy of a cetyltrimethylammonium bromide coated silica sphere from a flat bubble. Octadecyltrichlorosilane was used as a hydrophobic coating in the first two experimental methods. These experiments were recorded with a CCD camera to identify the detachment processes involved. Energies for both methods were calculated and divided into the two main steps of the detachment process: Three-Phase-Contact pinning and three phase contact line sliding. The first step represents the energy barrier which must be overcome before detachment can begin. It is directly related to contact angle hysteresis. Detachment occurs during the second step, where the solid-vapor interface is replaced by solid-liquid and liquid-vapor. This step corresponds to the work of adhesion. The effects of surface tension, contact angle and hysteresis were well demonstrated with the three experimental methods. Good correlation was found between theoretical work of adhesion and measured energies.Master of Science
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Yeung, Kim-wai Thomas. "Language and school children's misconceptions in energy and force". Click to view the E-thesis via HKUTO, 1988. http://sunzi.lib.hku.hk/HKUTO/record/B3862705X.
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Medendorp, Clare Aubrey. "ATOMIC FORCE MICROSCOPY METHOD DEVELOPMENT FOR SURFACE ENERGY ANALYSIS". UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/185.
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The vast majority of pharmaceutical drug products are developed, manufactured, and delivered in the solid-state where the active pharmaceutical ingredient (API) is crystalline. With the potential to exist as polymorphs, salts, hydrates, solvates, and cocrystals, each with their own unique associated physicochemical properties, crystals and their forms directly influence bioavailability and manufacturability of the final drug product. Understanding and controlling the crystalline form of the API throughout the drug development process is absolutely critical. Interfacial properties, such as surface energy, define the interactions between two materials in contact. For crystal growth, surface energy between crystal surfaces and liquid environments not only determines the growth kinetics and morphology, but also plays a substantial role in controlling the development of the internal structure. Surface energy also influences the macroscopic particle interactions and mechanical behaviors that govern particle flow, blending, compression, and compaction. While conventional methods for surface energy measurements, such as contact angle and inverse gas chromatography, are increasingly employed, their limitations have necessitated the exploration of alternative tools. For that reason, the first goal of this research was to serve as an analytical method development report for atomic force microscopy and determine its viability as an alternative approach to standard methods of analysis. The second goal of this research was to assess whether the physical and the mathematical models developed on the reference surfaces such as mica or graphite could be extended to organic crystal surfaces. This dissertation, while dependent upon the requisite number of mathematical assumptions, tightly controlled experiments, and environmental conditions, will nonetheless help to bridge the division between lab-bench theory and successful industrial implementation. In current practice, much of pharmaceutical formulation development relies on trial and error and/or duplication of historical methods. With a firm fundamental understanding of surface energetics, pharmaceutical scientists will be armed with the knowledge required to more effectively estimate, predict, and control the physical behaviors of their final drug products.
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Yeung, Kim-wai Thomas, i 楊劍威. "Language and school children's misconceptions in energy and force". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B3862705X.
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Ramos, Jose I. (Jose Israel). "Energy reduction strategies for existing Air Force healthcare facilities". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82165.
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Thesis (S.M. in Architecture Studies)--Massachusetts Institute of Technology, Dept. of Architecture, 2013.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 (p. 118-124).
Federal buildings are required to reduce 30% of their energy use intensities (energy use per square foot) by 2015 and 37.5% by 2020. Additionally, 15% of federal buildings are required to achieve an Energy Star Rating of 75 or above by 2015. Despite rigorous efforts, current Air Force healthcare building performance reveals only a 15% decrease has been achieved from the 2009 baseline levels and only 12% of the building inventory holds the Energy Star Rating. Projections similarly reveal full compliance by 2020 may not be achievable, therefore, the need for a comprehensive and more robust effort is proposed. This thesis seeks to develop a road map for the Air Force's 68 existing healthcare buildings towards compliance by 2015. A methodology has been developed that leverages the Air Force's state-of-the-art energy efficiency strategy, the building energy performance analysis for 68 healthcare facilities including ten in-depth case studies, and multi-agency interviews to produce the road map. Strategic energy management plans, building system retrofits, whole building retro commissioning, occupant behavior and medical equipment plug loads and standby loads have been assessed. Investment costs, energy savings, and return on investments present timeline objectives intended to deliver a comprehensive strategy towards energy savings in Air Force healthcare facilities by 2015. Findings indicate that an energy master plan that incorporates a systematic building diagnostics approach targeting HVAC equipment and system operations as the most effective strategy. The results reveal that HVAC retrofits and implementation of no cost measures such as temperature setpoints and setbacks collectively reduce building energy use by 85% and energy use intensities by 50% by 2015. Projections include a total budget request of $43.5 million, annual cost savings of $4.1 with a 9.4% return on investment.
by Jose I. Ramos.
S.M.in Architecture Studies
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Kasisira, Levi Lukoda. "Force modelling and energy optimization for subsoilers in tandem". Thesis, University of Pretoria, 2004. http://hdl.handle.net/2263/24925.
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In the recent past, as more farm power is being demanded on farms, due to increased farm sizes and operating speeds, larger and heavier farm machines are deployed in various farming operations. Their cumulative negative effects have become more apparent with increased incidences of soil compaction problems. This has forced many farmers to practice deep tilling, using subsoilers to break up compacted subsoil layers. In some maize growing regions of South Africa, conventional subsoilers are used in a tandem configuration. The farmers believe that the use of subsoilers in this mode reduces the draft force per unit area tilled. This probably happens because the critical depth for the rear subsoiler is increased beyond its working depth of 600 mm. Operating in this mode necessitated this study, with the ultimate goal of testing an appropriate existing force model for a single tine in predicting the force requirements of the front subsoiler in a tandem configuration. Secondly, to develop an alternative model for the rear subsoiler based on the three-dimensional failed soil-profile and to determine the relative position of the front subsoiler at which energy utilization is optimized. To develop the proposed model, an analytical approach based on limit equilibrium analysis was used and a Matlab-based computer program was coded to solve it. Its verification was conducted through field experiments in sandy clay loam soil. The experiments consisted of a continuous measurement of the horizontal and vertical forces acting on each subsoiler by a two-dimensional force transducer system. At the same time, the three-dimensional and thus the cross-sectional areas of the disturbed soil-profiles at different sections were measured, as well as the soil characteristics. A manual method employing a pin-profile meter was used to measure the vertical cross-sectional areas of the failed soil-profiles at 100 mm intervals. Further more, a technique using an automatic penetrometer and a computer program was developed to identify and map the three-dimensional failed soil-profiles. This technique indicated that the subsoiler failed the soil beyond its maximum operating depth and width. The results also indicated that the soil-failure pattern at close spacing is in phase at both subsoilers, leading to reduced total draft force requirements. At a wider spacing, the soil-failure pattern was out of phase, thus resulting in increased total draft force requirements. At the same time, the cross-sectional area tilled per unit draft force increased with increased spacing. This was because the failed maximum cross-sectional area increased in size faster than the total draft force as the spacing was increased. The proposed model verification results show that the predicted and recorded forces at the rear subsoiler correlated reasonably well at a wider spacing. When the front subsoiler was shallow working and close to the rear subsoiler, the model under- predicted the measured forces on the rear subsoiler, whilst the Swick-Perumpral model over predicted the applied forces to the front subsoiler and this was generally the case at wider spacings. Furthermore the efficiency of the subsoilers was maximized when the longitudinal spacing was such that it allowed the soil failed by the front subsoiler to stabilize before the rear subsoiler reached it. The maximum cross-sectional area failed per unit draft force was recorded when the depth of the front subsoiler was equal to about 80% of the rear subsoiler-operating depth. The knowledge contributed by this research will not only facilitate qualitative field operations and optimize energy use, but also promote better management decisions.Thesis (PhD (Engineering))--University of Pretoria, 2004.
Civil Engineering
unrestricted
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Hughes, Jeffrey S. "Comparison of Large Scale Renewable Energy Projects for the United States Air Force". Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/35282.
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This thesis focused on the performance of large-scale renewable energy projects for the United States Air Force. As global energy demands continue to rise, the need to find ways to save energy and produce alternative sources of energy will increase. The Federal Government has begun to address the challenge of energy production and energy security in recent years. In order to increase both the energy production and energy security for the Air Force, there is a trend to increase the amount of renewable energy produced on military installations. The goal of this research was to compare the estimated and actual performance of these large-scale on-site renewable energy projects at Air Force installations. The variables considered for this research were the execution methods and the renewable energy sources. The performance of each project was evaluated against factors identified in previous sustainable construction studies. The study found that actual performance of third party owned and operated projects differed from the expected performance by less than the Air Force owned and operated projects, and that performance of renewable energy projects differed from the expected performance by less than high performance buildings from previous studies. The study also found factors that contributed to the gap between the expected and actual performance including optimistic modeling, unusual weather, operational issues and higher than expected maintenance of the projects. The results of this research were an initial step in understanding the actual performance of large-scale renewable energy projects.Master of Science
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Lower, Steven K. "Mineral-Microbe Interactions Probed in Force, Energy, and Distance Nanospace". Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/26319.
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Biological force microscopy (BFM) was developed to quantitatively measure pico- to nano-Newton forces (10-9 to 10-12 N) as a function of the nanoscale distance (nanometers) between living bacteria and mineral surfaces, in aqueous solution. Native cells were linked to a force-sensing probe, which was used in a force microscope to measure attractive and repulsive forces as a mineral surface approached, made contact with, and subsequently withdrew from a bacterium on the probe. The resulting data were used to interpret the interactive dynamics operative between bacteria and mineral surfaces under environmentally relevant conditions.
BFM was used to study bacterial adhesion to mineral surfaces. In the case of Escherichia coli interactions with goethite, graphite, and muscovite, attractive and repulsive forces were detected at ranges up to 400 nanometers, the magnitude and sign depending on the ionic strength of the intervening solution and the mineral surface charge and hydrophobicity. Adhesion forces, up to several nanoNewtons in magnitude and exhibiting various fibrillation dynamics, were also measured and reflect the complex interactions of structural and chemical functionalities on the bacteria and mineral surfaces. In the study of Burkholderia cepecia interactions with mica, it was found that the physiological condition of the cell affected the observed adhesion forces. Cells grown under oligotrophic conditions exhibited an increased affinity for the mineral surface as opposed to cells grown under eutropic conditions.
BFM was also used to characterize the transfer of electrons from biomolecules on Shewanella oneidensis to Fe(III) in the structure of goethite. Force measurements with picoNewton resolution were made in aqueous solution under aerobic and anaerobic conditions. Energy values (in attoJoules) derived from these measurements show that the affinity between S. oneidensis and goethite rapidly increases by two to five times under anaerobic conditions where electron transfer from bacterium to mineral is expected. Specific signatures in the force curves, analyzed with the worm-like chain model of protein unfolding, suggest that the bacterium recognizes the mineral surface such that a 150 kDa putative, iron reductase is quickly mobilized within the outer membrane of S. oneidensis and specifically interacts with the goethite surface to facilitate the electron transfer process.Ph. D.
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O'Neill, Jason Darren. "Brute force polarisation of xenon-129". Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/13887/.
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In recent years the number of applications using NMR spectroscopy of hyperpolarised noble gases has expanded rapidly. The signal enhancement hyperpolarisation provides has led to its implementation in studies as diverse as materials science and biological imaging. 129Xe in particular, with its easily deformed electron cloud, is proving to be a uniquely sensitive probe for nanoporous structures. At present hyperpolarises gas production is limited to optical pumping (SEOP). In this study we investigate another approach, the brute force technique. At very low temperatures and high magnetic fields the Boltzmann distribution of spins for magnetic nuclei is heavily biased in a single direction. At temperatures below 10 mK and in magnetic fields of 15 T, 129Xe polarisations exceeding 40% are attainable. The utilisation of the brute force technique is hindered by the extraordinarily long relaxation time need for this polarisation to occur. In this study, we give details of our investigations of two relaxation catalysts, oxygen and helium-3. It is shown that paramagnetic molecular oxygen causes rapid relaxation of solid xenon at temperatures as low as 500 mK. We report on the enhanced relaxation, by liquid 3He of xenon films adsorbed on to silica gel and exfoliated graphite substrates. The investigation of this mechanism is extended to other magnetic nuclei and improved rates of relaxation are observed in 13C and 1 H. Details are also given, of how this mechanism of relaxation can be halted by the addition of superfluid 4He. Unique observations in the 129Xe NMR spectra are reported, providing a unique opportunity to study the coupling between individual layers of 129Xe atoms. Finally, a novel mechanism of cooling, by the filtering of energetic atoms through a porous ceramic membrane, is investigated.
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Lu, Shuo. "Impact energy absorption analysis of different thin-walled tubes with and without reinforcement". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/impact-energy-absorption-analysis-of-different-thinwalled-tubes-with-and-without-reinforcement(4b8efa4c-9743-4574-993e-1b9df3a922d2).html.
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For an ideal impact energy absorber, the initial peak force should be low and the average crushing force should be high. Also, a long stroke and a stable force history are expected. The thin-walled tube under axial loads is a kind of energy absorber that can produce controlled progressive collapse during a crash. It is a promising collapse mechanism for energy absorption with demonstrated success in industry. But the conventional thin-walled tubes still have high initial peak force and force fluctuations during a crushing process. To help to achieve a better energy absorbing structure, a research work has been carried out in this thesis. The aim of the present research is to achieve an improved understanding of the crushing behaviour of thin-walled tubes under axial loads. In the study, the entire crushing process, including the initial stage of collapse, its localization and the subsequent progressive folding has been carefully investigated by experiment. The relation between the localized plastic deformation and the corresponding crushing force is built by comparing the cross section of series of specimens and their load-displacement curves, which give a deep insight of the collapse mechanism of circular thin-walled tube under axial loads. Then some trigger systems are proposed, which is proved to be a good way to reduce the initial peak force and influence the collapse behaviour. To achieve higher energy absorbing efficiency, the multi-cell thin-walled tube has been investigated. Finally, based on the analysis in this study, a new multi-cell profile which is composed of coaxial tubes with different lengths and dented grooves is proposed. The new design is proved to be a good energy absorber with low initial peak force and very high energy absorption efficiency.
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Rodgers, Geoffrey William. "Next Generation Structural Technologies : Implementing High Force-To-Volume Energy Absorbers". Thesis, University of Canterbury. Mechanical Engineering, 2009. http://hdl.handle.net/10092/2906.
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This thesis explores the design development, experimental testing, and structural implementation of high force-to-volume (HF2V) damping devices. The development of damage-free structural design methods requires an alternate means of dissipating energy, as eliminating structural damage eliminates the primary energy dissipation mechanism. The HF2V devices developed within this thesis provide a damage-free energy dissipation mechanism and can be used in structures subjected to earthquake excitation. The devices developed are much smaller, more compact versions of lead extrusion dampers previously utilised for structural applications such as base-isolation. The devices provide the same force levels in a significantly smaller package, greatly extending the possible applications. Therefore, the development of these devices is a significant step towards developing damage-free structural design methods and reducing the impact of seismic events on a society.
The results indicate that the HF2V devices provide repeatable, consistent energy dissipation on repeated cycles, without any stiffness or strength degradation, and without any requirements for repair or replacement following an earthquake. This outcome is unique to these devices, and these characteristics are not available with the alternatives typically used within this field, such as yielding steel fuse-bars or proprietary viscous dampers. These devices therefore provide a unique opportunity to provide large energy dissipation in a very compact package that can easily be incorporated into a structural connection. At $100-300 each the devices cost several orders of magnitude less than proprietary viscous dampers and are much smaller physically, but provide equivalent or greater force capacity, making them an economically and technologically feasible option.
The devices are implemented into three structural systems, with numerous configurations tested for each structural system to provide alternate methodologies and delineate the contributions to response. The structural implementations show significant promise and highlight several key design recommendations to optimise their use. Finally, analytical models of varying complexity of the device and connection response are developed. The simple models are intended as an initial design tool, with the more detailed models developed as evaluation tools for initial designs. These models provide the tools to incorporate these devices into design practices and create a bridge to the profession.
Overall, this thesis develops high force-to-volume damping devices from an initial concept, through prototype development, to structural implementation and associated modelling. The key design issues are identified and significant progress is made towards this design approach receiving uptake by the profession.
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Reid, K. S. C. "Application of interactive force and energy calculations to enzyme-substrate docking". Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47803.
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Zhang, Jinhong. "Surface Forces between Silica Surfaces in CnTACl Solutions and Surface Free Energy Characterization of Talc". Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/29997.
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In general, the stability of suspension can be studied using two methods. One is to directly measure the forces between two interacting surfaces in media. The other is to study the interfacial surface free energies of the particles in suspension.
Direct surface force measurements were conducted between silica surfaces in octadecyltrimetylammonium chloride (C₁₈TACl) solutions using an Atomic Force Microscope (AFM). The results showed that the hydrophobic force existed in both air-saturated and degassed C₁₈TACl solutions. The attraction decreased with NaCl addition, and was the strongest at the point of charge neutralization (p.c.n.) of silica substrate.
The force measurement results obtained in CnTACl solutions showed that the attractions decayed exponentially and became the maximum at the p.c.n.'s. The decay lengths (D) increased with surfactant chain length. The measured forces were fitted to a charged-patch model of Miklavic et al. (1994) with rather large patch sizes. It was also found that the decay length decreased linearly with the effective concentration of the CH2/CH3 groups raised to the power of -1/2. This finding is in line with the model of Eriksson et al. (1989). It suggested that the long-range attractions are hydrophobic forces originating from the changes in water structure across a hydrophobic surface-solution interface.
For the TiO₂/water/TiO₂ system, the Hamaker constant was found to be 4±1×10-20 J. The force curves obtained in the TiO₂/CnTACl system showed a repulsion-attraction-repulsion transition with increasing surfactant concentration. The long-range attraction observed between TiO₂ surfaces in CnTACl solutions reached maximum at the p.c.n., and the decay length increased with chain length.
In present work, the thin-layer wicking technique was used to determine the surface free energy (γs) and its components of talc samples. The results showed that the basal surfaces of talc are weakly basic while the edge surfaces are acidic. The effect of chemicals on the surface free energies of talc was systemically studied. The results showed that CMC (carboxymethyl cellulose sodium salt) and EO/PO (ethylene oxide/propylene oxide) co-polymers made talc surface hydrophilic by increasing the surface free energies, especially γLW and γ -. SOPA (sodium polyacrylate) increased greatly the zeta-potentials instead of the surface free energies.Ph. D.
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President, Wai. "An analysis of the United States Air Force Energy Saving Performance Contracts". Thesis, Monterey, California, Naval Postgraduate School, 2007. http://hdl.handle.net/10945/38043.
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Approved for public release; distribution is unlimited.This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.
MBA Professional Report
The purpose of this paper is to explore the use of Enerrgy Saving Performance Contracts (ESPC) within the Department of Defense, focusing on the United States Air Force's utility and energy acquisition. The significant value of the ESPC is its alternative financing mechanism that authorizes Federal facilities regionalization without upfront investments. The paper focuses on Dyess Air Force Base's ESPC, as Dyess's benchmarking ESPC was selected for the Presidential Award recognition for Leadership in Federal Energy Management. The six major contracting processes within the three main management levels encompass many of the best-preactice characteristics. The interviews referenced herein with the service end-users, both the regional and local contracting officers, allow the reader to further understand how the Integrated Product Team's significant efforts resulted in a successful ESPC.
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Gue, David Leslie, i University of Lethbridge Faculty of Education. "Surveying alternative conceptions about energy in the classroom". Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Education, 1992, 1992. http://hdl.handle.net/10133/53.
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Secondary school pupils' concepts of energy were probed by clinical interviews and a multiple choice survey administered to 84 Alberta students. Preliminary information was gathered from curriculum documents, misconceptions literature and eight preliminary interviews. Both the interviews and the written survey were based on the interview-about-intances approach and used multiple-choice questions with free-response justification of answers. The wide range of alternative conceptions that were expressed paralleled findings of similar studies elsewhere. Most descriptions of energy were framed in substantive or ambiguous terms. Energy was frequently associated with living things, movement, and task performance. It was confused with concepts of heat, force, and pressure. Changes in physical systems were seen variously as consuming energy or as producing it upon demand. Aspects of a scientific conception were more evident among senior physics students, but differences between classes and grade levels did not generally reach statistical significance. Very few responses involved notions of energy as an abstract or conserved quantity. References to energy degradation or dissipation during changes were infrequent in interviews, survey responses, and curriculum documents. Subjects tended to choose similar responses on parallel interview and survey quesitions. Interview subjects showed evidence of preferred conceptual orientations towards a variety of situations, although their survey responses showed no parallel consistency. Conflicting evidence was obtained regarding the spontaneous use of energy-based descriptions of physical situations. Findings were interpreted from a constructivist stance, and implications for the study and teaching of specific topics were drawn. In addition, results suggested the efficacy of appropriate multiple choice instruments as an alternative to clinical interviews in the investigation of alternative conceptions.xi, 234 leaves : ill. ; 29 cm.
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President, Wai. "An analysis of the United States Air Force energy savings performance contracts". Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FPresident%5FMBA.pdf.
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"Submitted in partial fulfillment of the requirements for the degree of Master of Business Administration from the Naval Postgraduate School, December 2007."Advisor(s): Rendon, Rene G. ; Hudgens, Bryan J. "December 2007." "MBA professional report"--Cover. Description based on title screen as viewed on January 10, 2008. Includes bibliographical references (p. 71-75). Also available in print.
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Marley, Mathias Huuse. "Modelling and Robust Control of Production Force of a Wave Energy Converter". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26357.
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Lifesaver is a point-absorber wave energy converter developed by Fred. Olsen. She is currently deployed off the coast of England for pre-commercial testing. Lifesaver consists of a toroidal floater supporting three Power-Take Off (PTO) units moored separately to the seabed. The mooring lines are kept taut by electrical generators.Large force oscillations have been encountered in the mooring lines during testing. The source of force oscillations is identified as velocity fluctuations in the PTO drive train due to sudden saturation of generator torque. The unfavorable transient response is a result of low stiffness in the mooring line combined with large inertia in the drive train. A numerical model of the mooring line and PTO unit is developed for use in control system development. The system dynamics are identified through a frequency analysis of a linearized model. Based on these findings a Kalman filter observer is developed to estimate force and force gradient from the angular velocity of the electrical generator. Three different controllers are proposed to mitigate the undesirable force oscillations. The first prevents sudden saturation by limiting the generator force gradient, and should be straight-forward to implement. Proportional-derivative (PD) feedback of the rope force is enabled by the Kalman filter, and is shown to effectively mitigate the unwanted behavior. However, PD feedback reduces the stability margin of the controller and must be implemented with care. A control algorithm using hysteresis is explored. The hysteretic controller behaves in a predictable and similar manner independent of the incoming wave, and has the potential of increasing robustness during high sea states. Real-time optimization of the main control parameter using extremum seeking is explored. The algorithm may be used to track a time-varying optimum due to changes in sea state. The adaptation rate is limited by the high peak-to-average power ratio of Lifesaver.
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Hughes, Kristen. "The city as a community-based force for sustainability in energy systems". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 577 p, 2009. http://proquest.umi.com/pqdweb?did=1891601521&sid=6&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Lindsey, Beth A. "An investigation into student understanding of energy in the context of mechanics /". Thesis, Connect to this title online; UW restricted, 2008. http://hdl.handle.net/1773/9703.
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DURHAM, PHILIP R. "Force Field Development for Calbindin D9k". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218547540.
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Abdelkareem, Hasan. "Empowering students' scientific reasoning about energy through experimentation and data analyses". Diss., Connect to online resource - MSU authorized users, 2008.
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Thesis (Ph. D.)--Michigan State University. Dept. of Curriculum, Teaching, and Educational Policy, 2008.Title from PDF t.p. (viewed on July 7, 2009) Includes bibliographical references (p. 105-109). Also issued in print.
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Cho, Sung Nae. "Casimir Force in Non-Planar Geometric Configurations". Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11156.
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The Casimir force for charge-neutral, perfect conductors of non-planar geometric configurations have been investigated. The configurations were: (1) the plate-hemisphere, (2) the hemisphere-hemisphere and (3) the spherical shell. The resulting Casimir forces for these physical arrangements have been found to be attractive. The repulsive Casimir force found by Boyer for a spherical shell is a special case requiring stringent material property of the sphere, as well as the specific boundary conditions for the wave modes inside and outside of the sphere. The necessary criteria in detecting Boyer's repulsive Casimir force for a sphere are discussed at the end of this thesis.Ph. D.
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Simon, Todd R. "Microgripper force feedback integration using piezoresistive cantilever structure /". Online version of thesis, 2008. http://hdl.handle.net/1850/7855.
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Thomas, Jeffery Scott. "Helical force flow: a new engineering mechanics model for biological materials". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Thomas_09007dcc8063cfca.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed May 4, 2009) Includes bibliographical references (p. 103-113).
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Apeaning, Raphael Wentemi. "Energy Efficiency and Management in Industries : a case study of Ghana’s largest industrial area". Thesis, Linköpings universitet, Energisystem, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77558.
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The judicious use of energy by industries is a key lever for ensuring a sustainable industrial development. The cost effective application of energy management and energy efficiency measures offers industries with an effective means of gaining both economic and social dividend, also reducing the negative environmental effects of energy use. Unfortunately, industries in developing countries are lagging behind in the adoption of energy efficiency and management measures; as such missing the benefits of implementation. This study is aims at enhance the knowledge of industrial energy efficiency and management strategies in Ghana, by investigating the present level of energy (and efficiency) management practices in Ghana largest industrial park (i.e. Tema industrial area). The study also incorporates the investigation of also investigation of barriers to and driving forces for the implementation of energy efficiency measure; to shed light on the rationale for both the adoption and non-adoption of cost effective industrial energy efficient technologies in Ghana. This study was carried out using a semi-structure interview due to the explorative nature of the study. The interviews were conducted in sessions, in the first session respondents were asked describe the energy management strategies in used in the respective companies. In the second session, respondents were asked to fill a structured questionnaire covering the various aspects of the study. The results reveal that energy is poorly managed in the industrial area and there is an energy efficiency gap resulting from the low implementation energy efficiency measures. In addition the reveals that the important barriers impeding the implementation of cost effective energy efficiency technologies or measures in the surveyed firms principally stems from rational behavior economic barriers, which are deeply linked to the lack of government frameworks for industrial energy efficiency. The study also finds that economic gains related to ‘cost reductions resulting from lowered energy use’ and ‘threats of rising energy prices’ are the most important drivers for implementing energy efficiency measures or technologies.
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Andersen, Tomas. "Relier la dynamique de la force de tension cellulaire avec l'architecture de l'actine". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY056/document.
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La stabilité structurale et l'intégrité mécanique sont des éléments clés pour le bon fonctionnement et la préservation des systèmes vivants complexes. Étant en interaction constante avec leur environnement et en ce qui concerne les intrants externes, de tels systèmes doivent pouvoir faire face aux changements afin de prospérer. Ces entrées peuvent affecter le système dans son ensemble. Toute perturbation qui ne peut pas être supportée mécaniquement par le système vivant entraînera un dysfonctionnement crucial ou, en fin de compte, sa mort. Le mécanisme responsable du maintien des conditions physiologiques du système à l'état correct, malgré les variations environnementales, est identifié comme étant l'homéostasie. Plus précisément, le processus connu en mécanobiologie pour préserver l'équilibre mécanique approprié d'un système vivant est appelé homéostasie tensionnelle.Il est important de noter que tout ce qui précède est vrai à la fois à l'échelle du comportement collectif des organismes complexes et jusqu'au niveau de la cellule unique. En fait, c'est en fait cette dernière petite échelle qui nous intéresse. Les cellules font face à des perturbations mécaniques constantes de leur environnement et sont capables de répondre au maintien d'un état mécanique interne relativement stable. L'existence de cet équilibre tensionnel interne est liée à un processus très dynamique avec des boucles de rétroaction constantes entre les machines contractiles biochimiques internes et les forces actives externes générées.Notre intérêt est de comprendre ce mécanisme dynamique en perturbant dynamiquement le système homéostatique tensionnel en étudiant son retour à l'équilibreThe structural stability and mechanical integrity are key elements for the proper functioning and preservation of complex living systems. Being in constant interaction with their surroundings and subjected to external inputs, such systems need to be able to face changes in order to thrive. These inputs can affect the system both in a localized way or disturb it as a whole. Any perturbations that cannot be mechanically withstand by the living system will result in a crucial malfunctioning or, ultimately, in its death. The mechanism responsible for maintaining the system’s physiological conditions at the proper state, despite environmental variations, is identified as homeostasis. More specifically, the process known in mechanobiology to preserve the appropriate mechanical equilibrium of a living system is called tensional homeostasis.It is important to note that all of the above stated holds true both at the scale of collective behaviour of complex organisms, and all the way down to the single cell level. In fact, it is actually this last small scale which draws our interest. Cells face constant mechanical perturbations from their surrounding and are able to respond accordingly maintaining a relatively stable internal mechanical state. The existence of this internal tensional equilibrium relies on a very dynamic process with constant feedback loops between the internal biochemical contractile machinery and the external active generated forces.Our interest is to understand better this active mechanism by dynamically perturbing the tensional homeostatic system while studying its return to equilibrium
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Andersson, Erik, i Andreas Johansson. "The effect of driving force in Gibbs energy on the fraction of martensite". Thesis, KTH, Materialvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123597.
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The background to this bachelor thesis is an on-going project within the VINN Excellence Center Hero-m. The task in this thesis is to perform a literature survey about the martensite transformation and investigate how the resulting fraction depends on cooling below the Ms-temperature. Instead of calculating the undercooling for each of the known fractions of martensite the driving force will be evaluated. Several efforts have been made through the years to describe the relationships between fraction transformed austenite and temperature. The approaches to the first models were empirical and derived from collections of data regarding the amount of retained austenite at different quenching temperatures. Lately, studies have been made to derive a thermodynamical relationship using how the Gibbs energy is affected by increments in volume transformed austenite. Two equations are derived by calculating the resulting driving force at different known quenching temperatures and the respective percentage transformed martensite found in previous works. The data for the steels used show a characteristic slope when linearised. A trend for the steels which have a high characteristic slope is that they also have a high Ms temperature, and the steels which have a low characteristic slope tend to have a low Ms. Previous relationships which describe the martensitic transformation have considered the importance of the Ms temperature only in it being a starting temperature for the transformation. To further incorporate the Ms temperature in the equations presented, further research of the martensitic transformation is required. The approach in this thesis of using thermodynamically calculated data is a base for further investigation of the range of the martensite transformation.
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Lopes, Luiz Antonio Correa. "On the utilization of force-commutated AC controllers in AC power transmission systems". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40387.
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Recent economic pressures to enhance the transmission capability and controllability of existing power systems have led the new concept of Flexible AC Transmission System (FACTS). The use of power electronics in fast acting power controllers is one of the backbones of the implementation of FACTS.This thesis deals with the use of force-commutated Pulse Width Modulated (PWM) ac controller technology in phase-shifting and var compensation applications. The proposed technology employes as the building block a 4-switch PWM ac controller, which is controlled by means of duty cycle variation. The difficulties of using PWM in high power applications are overcome with a new multi-module PWM ac controller operated with symmetrically phase shifted carriers. This solution results in harmonic cancellation and consequently in high quality (less distortion) waveforms with the power switches (GTO) switching at low frequencies, thus keeping the communication losses low. The resulting power controllers can be considered as intermediate FACTS devices in terms of performance and flexibility.
An application of one phase-shifter and two var compensators in a tie line is also proposed for suppressing inter-area power oscillations. In this scheme the inter-area mode is deactivated if the FACTS devices keep constant the active and reactive power that flow in the tie line. Furthermore, the two interconnected subsystems were virtually decoupled with the proposed approach, in the sense that the small signal disturbances that occur in one side of the tie line do not affect the machines of the other side.
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Wagner, Christian. "Potential Energy Minimization as the Driving Force for Order and Disorder in Organic Layers". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38242.
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The topic of this work is the structural characterization and theoretical modeling of organic single and heterolayers. The growth of sub-monolayers and monolayers (ML) of the two polycyclic aromatic hydrocarbons quaterrylene (QT) and hexa-peri-hexabenzocoronene (HBC) on Ag(111) and Au(111) was investigated. A transition from a disordered, isotropic phase to an ordered phase with increasing coverage was found. The lattice of the ordered phase turned out to be coverage dependent. The intermolecular potential was modeled including Coulomb and van der Waals interaction by a force-field approach. The postulated repulsive character of the potential could be connected to the non-uniform intramolecular charge distribution and to a screening of the van der Waals forces. Furthermore, the influence of the variable lattice constant on the epitaxial growth of HBC was studied. The second part of this work deals with a ML of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on a ML of HBC. In dependency on the initial lattice constant of HBC, a total of three line-on-line (LOL) and point-on-line coincident phases of PTCDA (with respect to HBC) was found. Following an analysis of the general properties of LOL coincident systems via force-field calculations, a new method to predict the structure of such systems is introducedThema dieser Arbeit ist die strukturelle Charakterisierung von organischen Einfach- und Heterolagen sowie deren theoretische Beschreibung und Modellierung. Es wurden Submonolagen und Monolagen (ML) der polyzyklischen Kohlenwasserstoffe Quaterrylen (QT) und Hexa-peri-hexabenzocoronen (HBC) auf Ag(111) und Au(111) Einkristallen untersucht und ein Übergang von einer ungeordneten, isotropen Phase zu einer geordneten Phase mit steigender Bedeckung beobachtet. Die geordnete Phase wies dabei bedeckungsabhängige Gitterkonstanten auf. Das intermolekulare Potential wurde unter Berücksichtigung von Coulomb und van der Waals Anteilen mittels Kraftfeldmethoden modelliert. Der postulierte repulsive Charakter des Potentials konnte auf die Ladungsverteilung im Molekül und eine Abschwächung des van der Waals Potentials zurückgeführt werden. Weiterhin wurde der Einfluss der variablen HBC Gitterkonstante auf die epitaktische Relation des Gitters zum Metallsubstrat untersucht. Der zweite Teil der Arbeit widmet sich der Untersuchung einer ML 3,4,9,10-Perylenetetracarboxylic dianhydrid (PTCDA) auf einer ML HBC. Dabei wurden, in Abhängigkeit von der HBC Gitterkonstante, insgesamt drei verschiedene Typen von line-on-line bzw. point-on-line Epitaxie nachgewiesen. Im Anschluss an eine Analyse der generellen Eigenschaften solcher epitaktischer Lagen mittels Kraftfeldrechnungen wird eine neue Methode zur Vorhersage der Struktur konkreter Systeme vorgestellt
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Savin, Andrej. "Experimental Measurement of Lateral Force in a Submerged Single Heaving Buoy Wave Energy Converter". Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159519.
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The search for new solutions for the generation of energy is becoming more and more important for our future. Big arguments and disagreements on e.g. the questions of gas transport or the dependence on energy supplied by other countries raise demands on the development of new forms of alternative energy resources. Wave power is one of the main sources of renewable energy due to the high power density stored in ocean waves. Nevertheless, the dynamic forces of waves are so large that serious questions popped up on how to design a system which could work even in an unfavourable wave climate or could at least retain working capabilities after big storms without significant damages. This thesis studies the reliability of the mechanical parts of a linear direct driven permanent magnet generator. The results of offshore experiment where strain gauge sensors instrumented on the capsule and the inner framework structure are presented. Stress estimation analyses using strain gauges are carried out. A method for measuring forces and moments in the mechanical structure of the WEC is developed. Evaluation of the lateral force acting on the outer structure is a key factor for the design and construction of the WEC. A method for the measurement of the lateral force acting on the capsule has been developed. A study of the inclination angle between the Wave Energy Converter and the floating buoy has been carried out. The aim of this work is to contribute to the development of wave energy conversion system, and especially to the estimation of structural loads which are important for the survivability of the system under hard sea states. This work is a step that may influence future design of wave energy devices in terms of material aspect, survivability in a hard wave climate and cost-effective renewable energies.
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Verma, Abhinav. "Development and application of a free energy force field for all atom protein folding". Karlsruhe : Forschungszentrum Karlsruhe, 2007. http://d-nb.info/987646559/34.
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Shek, Jonathan K. H. "Reaction force control of a linear electrical generator for direct drive wave energy conversion". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/14404.
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Rivera, Allen. "Cost benefit analysis of integrated cots energy-related technologies for Army's force provider module". Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FRivera.pdf.
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Thesis (M.S. in Operations Research)--Naval Postgraduate School, September 2009.Thesis Advisor(s): Nussbaum, Dan. "September 2009." Description based on title screen as viewed on November 5, 2009. Author(s) subject terms: Net Zero Plus, Expeditionary Force Provider Kit, Fully Burdened Cost of Fuel, National Training Center, U.S. Army Soldier Systems Center Natick, Joint Capability Technology Demonstration. Includes bibliographical references (p. 69-72). Also available in print.
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Brereton, Helen. "Acuity of force appreciation in the osteoarthritic knee joint this thesis is submitted to the Auckland University of Technology in partial fulfilment of the requirements for the degree of Master of Health Science (MHSc), School of Physiotherapy, 2007 /". Click here to access this resource online, 2007. http://repositoryaut.lconz.ac.nz/theses/1340/.
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Thesis (MHSc--Health Science) -- AUT University, 2007.Primary supervisor : Professor Peter McNair. Includes bibliographical references. Also held in print (xi, 147 leaves : col. ill. ; 30 cm.) in North Shore Campus Theses Collection (T 617.582 BRE)
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Zhao, Sihong. "Energy harvesting from random vibrations of piezoelectric cantilevers and stacks". Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49030.
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Electromechanical modeling efforts in the research field of vibration-based energy harvesting have been mostly focused on deterministic forms of vibrational input as in the typical case of harmonic excitation at resonance. However, ambient vibrational energy often has broader frequency content than a single harmonic, and in many cases it is entirely stochastic. As compared to the literature of harvesting deterministic forms of vibrational energy, few authors presented modeling approaches for energy harvesting from broadband random vibrations. These efforts have combined the input statistical information with the single-degree-of-freedom (SDOF) dynamics of the energy harvester to express the electromechanical response characteristics. In most cases, the vibrational input is assumed to have broadband frequency content, such as white noise. White noise has a flat power spectral density (PSD) that might in fact excite higher vibration modes of an electroelastic energy harvester. In particular, cantilevered piezoelectric energy harvesters constitute such continuous electroelastic systems with more than one vibration mode.
The main component of this thesis presents analytical and numerical electroelastic modeling, simulations, and experimental validations of piezoelectric energy harvesting from broadband random excitation. The modeling approach employed herein is based on distributed-parameter electroelastic formulation to ensure that the effects of higher vibration modes are included. The goal is to predict the expected value of the power output and the mean-square shunted vibration response in terms of the given PSD or time history of the random vibrational input. The analytical method is based on the PSD of random base excitation and distributed-parameter frequency response functions of the coupled voltage output and shunted vibration response. The first one of the two numerical solution methods employs the Fourier series representation of the base acceleration history in a Runge-Kutta-based ordinary differential equation solver while the second method uses an Euler-Maruyama scheme to directly solve the resulting electroelastic stochastic differential equations. The analytical and numerical simulations are compared with several experiments for a brass-reinforced PZT-5H cantilever bimorph under different random excitation levels.In addition to base-excited cantilevered configurations, energy harvesting using prismatic piezoelectric stack configurations is investigated. Electromechanical modeling and numerical simulations are given and validated through experiments for a multi-layer PZT-5H stack. After validating the electromechanical models for specific experimentally configurations and samples, various piezoelectric materials are compared theoretically for energy harvesting from random vibrations. Finally, energy harvesting from narrowband random vibrationsusing both configurations are investigated theoretically and experimentally.
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Mitrokhin, Alexey. "Energy saving in the process of gas pipeline overhaul". Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-149322.
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The problem of energy saving during overhaul of a linear part of gas trunkline is regarded in this paper. This issue has been analyzed from different perspectives. Thermodynamic analysis of gas evacuation from a string that is off operation for the overhaul to a parallel or adjacent string with the use of mobile compressor systems was made. Economical attractiveness of mobile compressor systems applications was proved. Various methods of gas trunklines linear parts overhaul have been considered. For each of the methods problems of minimization of necessary for the overhaul amount of energy consuming machines have been solved. The results can be used in the development of overhaul projects of the gas trunklines linear parts.
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Li, Xinbi. "Developing and Validating a Complete Second-order Polarizable Force Field for Proteins". Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-dissertations/196.
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One of the central tasks for biomolecular modeling is to develop accurate and computationally cheap methods. In this dissertation, we present the development of a brand new polarizable force field—Polarizable Simulations with Second order Interaction Model (POSSIM) involving electrostatic polarization. The POSSIM framework combines accuracy of a polarizable force field and computational efficiency of the second-order approximation of the full-scale induced point dipole polarization formalism. POSSIM force field has been extended to include parameters for small molecules serving as models for peptide and protein side-chains. Parameters have been fitted to permit reproducing many-body energies, gas-phase dimerization energies and geometries and liquid-phase heats of vaporization and densities. Quantum mechanical and experimental data have been used as the target for the fitting. The resulting parameters can be used for simulations of the parameterized molecules themselves or their analogues. In addition to this, these force field parameters have been employed in further development of the POSSIM fast polarizable force field for proteins. The POSSIM framework has been expanded to include a complete polarizable force field for proteins. Most of the parameter fitting was done to high-level quantum mechanical data. Conformational geometries and energies for dipeptides have been reproduced within average errors of ca. 0.5 kcal/mol for energies of the conformers (for the electrostatically neutral residues) and 9.7º for key dihedral angles. We have also validated this force field by simulating an elastin-like polypeptide GVG(VPGVG)3 in aqueous solution. Elastin-like peptides with the (VPGVG)n motif are known to exhibit anomalous behavior of their radius of gyration that increases when temperature is lowered (the so called inverse temperature transition). We have simulated the system with the OPLS-AA and POSSIM force fields and demonstrated that our newly developed polarizable POSSIM parameters permit to capture the experimentally observed decrease of the radius of gyration with increasing temperature, while the fixed-charges OPLS-AA ones do not. Furthermore, our fitting of the force field parameters for the peptides and proteins has been streamlined compared with the previous generation of the complete polarizable force field and relied more on transferability of parameters for non-bonded interactions (including the electrostatic component). The resulting deviations from the quantum mechanical data are similar to those achieved with the previous generation, thus the technique is robust and the parameters are transferable. At the same time, the number of parameters used in this work was noticeably smaller than that of the previous generation of our complete polarizable force field for proteins, thus the transferability of this set can be expected to be greater and the danger of force field fitting artifacts is lower. Therefore, we believe that this force field can be successfully applied in a wide variety of applications to proteins and protein-ligand complexes.
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Rivai, Kathryn. "Data analysis of experimental test results of a wave energy converter for the WECfarm project". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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There are different technologies to exploit marine energy, one of these is wave energy converters (WEC), that use the energy of the waves to produce electricity. To maximize the power production, the WECs are placed in arrays with specific geometric configurations, therefore it is important to study the interaction between the WECs (near-field interactions) and the effects of the WEC array on the waves behind the array (far-field effects).
A single ‘Master WEC’ is being developed, tested and fine-tuned prior to the array layout tests. The aim is to investigate and improve the behavior of the new WEC design, through tests in different waves conditions. The new shape of the WEC has been designed using a numerical study in order to improve the behavior of the WEC, reducing the surge force and increasing its radiation. The objective of this master dissertation is to study the behavior of the scale model (scale factor 0.525) of the hydrodynamic part of the WEC. Several tests were performed in the wave flume in the laboratory of Ghent University, and the obtained database was subsequently analyzed.
First a free decay test was performed to determine the natural period and the damping factor of the buoy.
Then the results from regular waves tests were analyzed to determine the interaction between two buoys using regular waves with different wave periods.
Several tests were conducted to quantify the horizontal and vertical forces acting on the buoy unit, with differing dispositions of the load cells and differing wave heights and periods.
All the tests were performed with a water depth of 0.65 m.
The data obtained from the measuring devices in the tests was processed with MATLAB to check the repeatability of the tests, to obtain graphs, averaged values of the forces and the acceleration acting on the buoy unit, amplitude and phase of the oscillatory motion of the buoy.
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Tahiraj, Klein. "Piezoelectric force microscopy study on zinc tin oxide nanowires". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19405/.
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Self-powered sensor devices could find widespread application to monitor personal health, automobiles or buildings. One of the most ubiquitous form of energy on which these devices could rely is vibrational energy. To convert this energy into electrical energy, the research is focusing on piezoelectric materials. Examples of these materials are ZnO or Zinc Tin Oxides (ZTO). Modelled into nanowires and incorporated into an elastomer at the University of Lisbon, these materials have been demonstrated to result in macroscopically efficient energy conversion. In this work, I use Piezoelectric Force Microscopy to characterize the piezoelectric response of a single ZTO nanowire, namely, to measure the component d33 of its piezoelectric strain tensor. P(VDF-TrFE) thin film, i.e. a material with well characterized piezoelectric proprieties, is used to calibrate the instrument sensitivity. The value I obtain for the d33 of the ZTO nanowire is 23.70±0.04pm/V. In order to use it as a reference, I perform a characterization also for a ZnO nanowire. The value I obtain is 10.36±0.03pm/V. The value for the ZTO nanowire is therefore about double that of the ZnO. This result certifies ZTO nanowires as good candidates for energy conversion in future self-powered devices.
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Nitzsche, Nico, Lutz Baumgärtel, Christian Maiwald i Henry Schulz. "Reproducibility of Blood Lactate Concentration Rate under Isokinetic Force Loads". MDPI AG, 2018. https://monarch.qucosa.de/id/qucosa%3A33156.
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(1) Background: Maximum isokinetic force loads show strongly increased post-load lactate concentrations and an increase in the maximum blood lactate concentration rate ( V˙ Lamax), depending on load duration. The reproducibility of V˙ Lamax must be known to be able to better assess training-related adjustments of anaerobic performance using isokinetic force tests. (2) Methods: 32 subjects were assigned to two groups and completed two unilateral isokinetic force tests (210° s−1, Range of Motion 90°) within seven days. Group 1 (n = 16; age 24.0 ± 2.8 years, BMI 23.5 ± 2.6 kg m−2, training duration: 4.5 ± 2.4 h week−1) completed eight repetitions and group 2 (n = 16; age 23.7 ± 1.9 years, BMI 24.6 ± 2.4 kg m−2, training duration: 5.5 ± 2.1 h week−1) completed 16 repetitions. To determine V˙ Lamax, capillary blood (20 µL) was taken before and immediately after loading, and up to the 9th minute post-load. Reproducibility and variability was determined using Pearson and Spearman correlation analyses, and variability were determined using within-subject standard deviation (Sw) and Limits of Agreement (LoA) using Bland Altman plots. (3) Results: The correlation of V˙ Lamax in group 1 was r = 0.721, and in group 2 r = 0.677. The Sw of V˙ Lamax was 0.04 mmol L−1 s−1 in both groups. In group 1, V˙ Lamax showed a systematic bias due to measurement repetition of 0.02 mmol L−1 s−1 in an interval (LoA) of ±0.11 mmol L−1 s−1. In group 2, a systematic bias of −0.008 mmol L−1 s−1 at an interval (LoA) of ±0.11 mmol L−1 s−1 was observed for repeated measurements of V˙ Lamax. (4) Conclusions: Based on the existing variability, a reliable calculation of V˙ Lamax seems to be possible with both short and longer isokinetic force loads. Changes in V˙ Lamax above 0.11 mmol L−1 s−1 due to training can be described as a non-random increase or decrease in V˙ Lamax.
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O'Connell, Sean. "Shapes of Edges: Exploring the notion of boundary, drawing on experiments in force and form". Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/15927.
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Shapes of edges explores the boundaries we perceive - the surfaces of objects we touch, constellations in the night sky, the fenced borders of home and nation, lines between animate and inanimate, and the outer edges of the ideals which we hold to our hearts. Through elaborate physical experiments in force and form, and applied philosophical thought, the underlying structures of knowledge which we use to define the world are examined. Three basic experiments, documented in detail, form the foundation of the study. The physical experiments are: colliding of hollow metal boxes in air; studies of smoke vortex formation; and spark discharge imaging of solid forms. Machines are purpose-built for the experiments, and documentation carried out in traditional and alternative media. Many of the methods of recording require bespoke apparatus, created with a single process in mind, and the processes inevitably become entangled with expectation, perception, and habitual patterns of thought. The experiments and the machines, the documentation and their processes, the exhibited work, the philosophical research, and these written words, all merge. Such a mesh of information creates rich ground for new knowledge, arising from an intimate relation of disparate parts, all brought to bear upon one notion, that of boundary.
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Ghadirian, Bahman. "A new regularization procedure for calculating the Casimir energy". Thesis, View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/24942.
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This thesis deals with the concepts of a very interesting phenomenon in quantum physics, the Casimir effect. Here the effect is investigated in detail and its importance to other areas of physics is analysed. The Casimir effect is produced by disturbing the vacuum energy when material boundaries or background fields are introduced in the vacuum. The usual approach to this effect is the vacuum fluctuation that has been studied in the past in relation to the discussion of the zero-point energy as a result of the field resemblance to the quantum harmonic oscillators, where residual ground state energy must be considered. In this thesis a new method to study vacuum fluctuations is presented. This new approach to the problem which is more classical is based on the Heisenberg uncertainty principle and the very important fluctuation-dissipation theorem. The other aim of the thesis is to implement a new algorithm for regularizing the Casimir energy for a massive scalar field. Unlike the previous works on this problem by other authors that give approximate results, this attempt will produce precise results. My method is based on a new regularization procedure that allows us to employ the very reliable dimensional regularization scheme in place of a more mathematically complicated zeta-function regularization procedure. In order to achieve this goal I will deal with the problem by using the Euler-Maclaurin summation formula. The result will be a regularized Casimir energy for the case of a massive scalar field. This model may be used for the other geometrical boundaries and different fields.
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Goeke, Robert P., i Christopher M. VanZoest. "The art of the deal: how can the Air Force successfully execute renewable energy transactions?" Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/10489.
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MBA Professional ReportThe purpose of this paper is to explore the methods the Air Force uses to procure renewable energy. To comply with Executive Order 13423, agencies must ensure that at least half of all renewable energy required under Energy Policy Act of 2005 comes from new renewable sources (developed after January 1, 1999) (Department of Energy, n.d.b). The Air Force is currently on track to meet the requirements of this legislation and is also the Department of Defense (DoD) leader in total renewable energy procured. The contracting tools used to procure renewable energy are Power Purchase Agreements and Enhanced Use Leases. The processes involved with Power Purchase Agreements and Enhanced Use Leases are unique and challenging. Additionally, renewable energy procurement includes many other participants or interested parties, which is contrary to the standard contracting process. Working within this renewableenergy arena requires the use of public-private partnerships in order for these deals to be successful. This paper will describe and evaluate the entire process used to procure renewable energy including parties involved, tools to execute, examples of successful projects, and it will explain how the Air Force can better support the procurement of renewable energy.
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Snell, Lloyd Dale. "Force and moment analysis of stacked counter rotating eccentric mass tree shaker energy-wheel system". [Ames, Iowa : Iowa State University], 2008.
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Kim, Junghoon. "The influence of force production and eccentric exercise on growth hormone". Virtual Press, 1997. http://liblink.bsu.edu/uhtbin/catkey/1048386.
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The main purpose of this study was to investigate the relationship between human growth hormone (hGH) and two separate components of resistance exercise. Eight non-weight-trained subjects (23.33 ± 0.3 yrs) performed three force production trials (FPT), at different concentric workloads, and an 120% eccentric exercise trial (EET) on the Cybex 6000. Blood samples (3 mls) were taken pre- and post-exercise and analyzed for lactate, creatine kinase (CK) and hGH. Electromyographic (EMG) activity of the quadriceps muscle was recorded during each trial. The mean peak torque produced during the FPTs increased as work intensity increased but was the highest in the EET. The data for total work showed a proportional relationship with the intensity of the three concentric work loads but not the 120% EET. EMG activity of vastus medialis (VM) and rectus femoris (RF) measured during EET was 26% less than RF of 50% and 15% less than VL of 70% in FPT, respectively. The highest hormonal response occurred following the 120% EET. The hormonal response following the FPTs was highest in the 90% FPT with the two lower work intensity trials (50 and 70%) showing no clear hormonal response. Although the hGH response was the highest in the 120% EET, the post-exercise lactic acid levels in EET were 24% less than that of the 90% FPT. Creatine kinase (CK) activity was significantly elevated 36 hours after the last bout of EET which suggests that the eccentric exercise resulted in muscle damage. The results from concentric trials showed that muscle force generation, EMG, and lactic acid of the three different concentric trials were well correlated to the pattern of hGH secretion. However, only peak torque was consistent with the hGH response of the EET. The highest peak torque and hGH levels were achieved with eccentric exercise. The highest levels of fatigue, as a result of the combination of longer exercise time and overloading of the muscle during EET, may explain the higher hGH output. The muscle damage caused by the eccentric trial was enough to induce delayed onset of muscle soreness and may be the stimulus for the higher hGH output. The hGH response may facilitate repair of the muscular damage induced by eccentric exercise by promoting protein synthesis.School of Physical Education
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Chen, Wei. "The force regulation on binding kinetics and conformations of integrin and selectins using a bio-membrane force probe". Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/33814.
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Cell adhesion plays an important role in inflammation and immunological responses. Adhesion molecules (e.g., selectins and integrins) are key modulators in mediating these cellular responses, such as leukocyte trafficking under shear stress. In this thesis, we use a bio-membrane force probe (BFP) to study force regulation on kinetics and conformations of selectin and LFA-1 integrin. A new BFP was built up, and a new assay, using thermal fluctuation of the BFP, was developed and used to monitoring selectins and their ligands association and dissociations. The new BFP was also used to investigate the force and force history dependence of selectin-ligand interactions. We found tri-phasic transition of force-dependent off-rates and force-history dependence of selectin/ligaind interactions. The BFP was also used to characterize force-dependent lifetimes of the LFA-1-ICAM-1 interaction. We found that LFA-1/ICAM-1 bonds behaved as catch bond and that LFA-1-ICAM-1's catch bonds were abolished blocking the downward movement of αA domain α7 helix. Finally, the BFP was applied to dynamically probe the global conformational changes of LFA-1 and to characterize force-regulated transitions among different conformational states on a living cell. We observed dynamic transitions of LFA-1 between extended and bent conformations on living cells. The observed average distance change of LFA-1's extensions was about 18nm, while that of the bending was only about 14nm. We also found that forces could facilitate extension but they slow down the bending of LFA-1. The observed transition time of extension was less than 0.1s, while that of contraction was longer than 0.2s. Our observations here are the first in-situ evidence to demonstrate how integrins dynamically transit different conformations and how force regulates these transitions.
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Estep, Joseph Jeremiah. "Analog and numerical experiments investigating force chain influences on the bed physics of dense granular flows". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51768.
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Granular materials are composed of solid, discrete particles and exhibit mechanical properties that range from fluid to solid behavior. Some of the complexity exhibited by granular systems arises due to the long-range order that develops due to particle-particle contact. Inter-particle forces in granular materials often form a distributive network of filamentary force-accommodating chains (i.e. force chains), such that a fraction of the total number of particles accommodates the majority of the forces in the system. The force chain network inherent to a system composed of granular materials controls the macroscopic behavior of the granular material. Force transmission by these filamentary chains is focused (or localized) to the grain scale at boundaries such as the granular flow substrate. Recent laboratory experiments have shown that force chains transmit extreme localized forces to the substrates of free surface granular flows. In this work we combine analog and numeric experimental approaches to investigate the forces at the bed of a simplified granular flow. A photoelastic experimental approach is used to resolve discrete forces in the granular flows. We also conduct discrete element method (DEM) simulations, using input parameters derived from measureable physical material properties of experimental and natural materials, which successfully reproduce the analog experimental results. This work suggests that force chain activity may play an unexpected and important role in the bed physics of dense granular flows through substrate modification by erosion and entrainment, and that DEM numerical methods effectively treat force chain processes in simulated granular flows.
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Lu, Lingbo. "STUDIES OF ORGANIC COMPOUNDS SPREADING OVER HIGH ENERGY SURFACES". UKnowledge, 2013. http://uknowledge.uky.edu/chemistry_etds/21.
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Spreading plays an important role in coating, lubrication, printing and etc. During the spreading process, a liquid thin film forms prior to the expansion of a liquid drop. This thin film is called a precursor film. It not only changes the spreading mechanism, but impacts the wettability of a liquid. Early studies on the precursor films showed the films were stacked in a terraced structure, and the radius of each layer of the films was proportional to the square root of time. Optical techniques such as ellipsometry, X-ray diffraction and X-ray reflectivity solved the conformations of liquid molecules at the interfaces. However, the conformations of the interfacial molecules have rarely been correlated with their positions at the interface. In addition, the properties of the precursor films have not been fully studied yet.
In this dissertation, two kinds of organic compounds, hexatriacontane (C36) and 1-butyl-3-methylimidazolium ([Bmim][Cl]), are proposed to be spread over octadecyltrichlorosilane partially degraded (OTSpd) patterned surfaces. Once organic molecules flow over such OTSpd surfaces, the liquids are limited within the patterned area. Characterized by atomic force microscopy (AFM), the structures and chemical identities and the formation mechanism of the precursor films are resolved thereafter.
The precursor films formed by both compounds, C36 and [Bmim][Cl], were observed in a bilayer structure in that the molecules close to the solid substrate had different orientation from the molecules close to the air. They were called parallel layers and standing-up layers, respectively. The parallel layers of C36 formed prior to the standing-up layers through the vapor phase transport. In addition, the parallel layers were found more stable thermodynamically and the standing-up layers were more stable mechanically. The frictional study of C36 showed the standing-up layers could hold 0.49GPa pressure. The orientation of [Bmim][Cl] molecules were impacted by the polarities of the solid substrates.
The achievements in this dissertation not only resolve the properties of the precursor films of two organic compounds, but provide a general method for the further studies of the precursor films.