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1
Thompson, Melissa Anne. "Mechanical power output in sprint cycling". Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446102.
Testo completo
2
Spahic, Edin. "Piezoelectric power harvesting from mechanical strain". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86163.
Testo completoAbstract (sommario):
Piezoelectric power harvesting is a field of active research. Most piezoelectric power harvesters are designed around harvesting energy from vibrations. This thesis is a feasibility study in collaboration with SKF to investigate whether or not a useful amount of power can be extracted from a piezoelectric tube mounted inside the roller of a bearing, based purely on harvesting power from mechanical strain instead of ambient vibrations, with the goal of replacing bulky single-use batteries as the power source for SKF's sensor roller technology. The methodology consisted of constructing and simulating a multiphysics model in COMSOL Multiphysics, and simulations were performed using three sets of parametric studies. Necessary material properties for the middle epoxy layer bonding the roller and piezo tube together were determined, before characterizing the piezoelectric behavior in relation to the magnitude of the applied load and the rotation of the roller. Simulation results indicate that approximately 0.64mW of power can be harvested from a single piezo tube under nominal operation in the test case, which is sufficient to power the sensor roller circuitry. In addition to simply replacing batteries as a power source, the technology opens up possibilites for more widespread adoption of sensor rollers in other applications.
3
Springer, Alexander D. "Optimizing cycling power". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105573.
Testo completoAbstract (sommario):
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.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 29).
In this study we determine a viable bioenergetic model for power allocation during a cycling race. Various models have been proposed to address power allocation in races with two models rising above others: the Morton-Margaria Three Tank model and the Skiba Energy Balance model. The energy balance model was implemented in MATLAB and compared against the gold standard implementation in Golden Cheetah to model the depletion of an athlete's energy over the course a ride. The implementation of the model was successful as verified by ride data from a cyclist in the 2014 Tour de France. Additionally, the model was further tested with sample power profiles in order to understand the depletion of energy over the course of a ride. Two key findings emerged from the investigation. First, we require a better account of exhaustion in the energy balance model which can be achieved by weighting the time spent below critical power over the time spent above critical power. This is because a cyclist becomes more exhausted by efforts at higher power outputs compared to the recovery at an effort below critical power. Second, energy balance models should use a variable time constant as rides and races have highly variable recovery periods below critical power which affects the ability of an athlete to reconstitute their energy. Use of a variable time constant could address the weighting of efforts below critical power identified in the first finding as well.
by Alexander D. Springer.
S.B.
4
Fucetola, Jay J. "Mesofluidic magnetohydrodynamic power generation". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74463.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 161-162).
Much of the previous research into magnetohydrodynamics has involved large-scale systems. This thesis explores the miniaturization and use of devices to convert the power dissipated within an expanding gas flow into electricity. Specific properties, such as high surface tension, allow for unique possibilities in the design of such devices. The material covered includes a brief derivation of the theory describing steady well-developed MHD flows within circular and rectangular channels. Numerical simulations are used to elucidate the relationships derived theoretically and to enable future design without the reliance upon such simulation. Fabricated devices are experimentally observed to determine the agreement with the modeled behavior. Finally, a design is proposed that is predicted to be a viable generator as well as a means for further examining the unanswered questions raised by the research performed in this thesis.
by Jay J. Fucetola.
S.M.
5
Douglas, Keith P. (Keith Preston). "Shipboard aggregate power monitoring". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/50557.
Testo completoAbstract (sommario):
Thesis (Nav. E. and S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references (p. 96-100).
Modem naval warships rely on vast arrays of sensor networks to evaluate the performance of mission critical systems. Although these sensor networks enable increased levels of automation, they are costly to install and to maintain. The power distribution network offers an alternative solution for tracking the performance of mission critical systems. Research conducted at Massachusetts Institute of Technology's Laboratory for Electromagnetic and Electronic Systems (LEES) has proven that the power distribution network contains vital information that can provide performance monitoring and automatic diagnostic functions. This thesis will address the issue of sensor-count reduction through the application of Non-Intrusive Load Monitoring (NILM) technology. Theoretical studies and field experiments will be presented in order to demonstrate the NILM's ability to correlate load activity with power measured from an aggregate level in the distribution system. Additionally, a critical evaluation is conducted on the current NILM configuration's ability to perform automated classification. Findings will be supported using data collected from NILMs monitoring power flow on board the U.S. Coast Guard Cutter ESCANABA (WMEC-907).
by Keith P. Douglas.
Nav.E.and S.M.
6
Yu, Chien-Ning 1970. "Real power and frequency control of large electric power systems under open access". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38154.
Testo completo
7
Lin, Cynthia S. B. Massachusetts Institute of Technology. "Feasibility of using power steering pumps in small-scale solar thermal electric power systems". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43016.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaves 59-60).
The goal of this study was to determine performance curves for a variety of positive displacement pumps in order to select an efficient and low cost option for use as a boiler feed pump in a 1-kWe organic Rankine cycle (ORC) system built by the Solar Turbine Group in Lesotho. The pumps tested included OEM plunger and piston pumps, and rotary vane-type power steering pumps purchased from a junk yard. Motor speed and torque were measured at different flow rates to determine the power consumed to move fluid in the prescribed pressure regime. The test station was designed to pump deionized water; it was intended that measurements and calculations would then be non-dimensionalized and used to predict the ORC working fluid's properties. Unfortunately, deionized water caused the power steering pump shafts to seize; the efficiencies were below anticipated and the pumps were unable to operate under the specified pressures. It was discovered, after WD-40 was added to the water, that power steering pumps performed best when moving fluids with more lubricity. The optimal pump was selected based on how the pump efficiency affected the overall ORC system efficiency, defined as the electrical work output divided by the heat input, and the net electric power output. Power steering pumps achieved efficiencies between 34%-54% under the desired ORC operating conditions with water-oil emulsion as the working fluid. For that pump efficiency range, the overall solar thermal electric ORC system efficiency would be 7.4%-8.5% and the overall system cost would be USD 4.59-5.27 per installed Watt. Made specifically for pumping hydroflurorcarbons, the working fluid used in STG's ORC, the OEM Dynex pump exhibited poorer performance than predicted. The pump efficiency of 31% gave a system efficiency of 7.1% and a cost of USD 6.40 per installed Watt. The OEM water piston and plunger pumps made by Hypro achieved efficiencies of 70% and 81%, respectively, under the same ORC operating conditions described above.
(cont) For those pump efficiencies, the overall system efficiencies would be 9.0% and 9.2% and the costs would be USD 4.58 and 4.63 per installed Watt, respectively. The most optimal pump is the HyproPiston pump; although it costs nearly six times that of a power steering pump, the overall system cost is lower when normalized over the power output.
by Cynthia Lin.
S.B.
8
Forsik, Stéphane Alexis Jacques. "Mechanical properties of materials for fusion power plants". Thesis, University of Cambridge, 2009. https://www.repository.cam.ac.uk/handle/1810/221725.
Testo completoAbstract (sommario):
Fusion power is the production of electricity from a hot plasma of deuterium and tritium, reacting to produce particles and 14 MeV neutrons, which are collected by a cooling system. Their kinetic energy is transformed into heat and electricity via steam turbines. The constant ux of neutrons on the rst wall of the reactor produces atomic displacement damage through collisions with nuclei, and gas bubbles as a result of transmutation reactions. This leads eventually to hardening and embrittlement. Designing a material able to withstand such intensity of damage is one of the main aims of research in the field of controlled fusion. In the past decades, many experiments have been carried out to understand the formation of radiation-induced damage and quantify the changes in mechanical properties of irradiated steels, but the lack of facilities prevents us from testing candidate materials in a fusion-like environment. Modelling techniques are utilised here to extract information and principles which can help estimate changes in steels due to damage. The elongation and yield strength of various low-activation ferritic/martensitic steels were modelled by neural networks and Gaussian processes. These models were used to make predictions which were compared to experimental values. Combined with other techniques and thermodynamic tools, it was possible to understand the evolution of the mechanical properties of irradiated steel, with a particular focus on the role of chromium and the roles of irradiation temperature and irradiation dose. They were also used to extrapolate data related to fission and attempt to make predictions in fusion conditions. A set of general recommendations concerning the database used to train the neural networks were made and the usage of such a modelling technique in materials science is discussed. An attempt to optimise the performance of neural networks by suppressing some random aspects of the training is presented. Models of the elongation, yield strength and ductile-to-brittle transition temperature trained following this procedure were created and compared to classical models.
9
Gibson, James Samuel Kwok-Leon. "Mechanical behaviour of irradiated tungsten for fusion power". Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:400a6537-2fc2-4298-821d-b73a84f1f52b.
Testo completoAbstract (sommario):
Tungsten will be a key material for the plasma-facing components in future fusion devices. Its mechanical performance under neutron irradiation will strongly influence the lifetime of these devices. Pure tungsten has been subjected to a variety of irradiating species - tungsten ions, helium ions and fission neutrons - between 500°C and 900°C and the change in mechanical properties measured by micro-mechanical testing methods. Pure tungsten has been ion-irradiated using self-ions and helium ions at 500°C and 800°C. Nanoindentation has been performed on all specimens, and the 800°C specimens have been tested at temperatures up to 750°C using high-temperature nanoindentation. The irradiation temperature has no effect on the hardening of tungsten. Hardening from self-ion irradiation has not saturated by 4.5 dpa with an increase in hardness of 3.3 GPa. The hardening from helium implantation is only 0.73 GPa, and a comparison with literature shows that this hardening only depends on the concentration of the injected helium. The difference is likely due to the much smaller defect size of helium-vacancy clusters when compared to dislocation loops. High-temperature nanoindentation shows that helium-implanted tungsten softens rapidly, with the hardening from the radiation damage becoming negligible above 450°C. Self-ion implanted tungsten does not soften by 650°C, again likely due to the size difference of the defects. Micro-mechanical tests - namely micro-cantilever bending - have been used to investigate the plastic and fracture characteristics of tungsten before and after irradiation. Plastic behaviour is dominated by size effects due to the 3 μm depth of the implanted layers, which makes nanoindentation a better method for investigating radiation damaged layers. In fracture testing, fracture is rarely seen. Using the yield stress to calculate fracture toughness, the hardening from irradiation damage results in an increase in fracture toughness from 2.2 MPa√m to 6.0 MPa√m. The work of deformation at 1% is also increased after irradiation from 7.2 x 10-11 Nm to 2.8 x 10-10 Nm, implying that the implanted damage is not leading to an increase in embrittlement by reducing K1c. Neutron irradiated tungsten also shows an increase in fracture toughness after irradiation from 6.5 MPa√m to 14.5 MPa√m. However, the BDTT increases by ∼ 100°C in poly-crystal tungsten and ∼ 500°C in single-crystal tungsten. The difference in BDTT does not exist in the unimplanted material. The change after irradiation is likely due to the fine (˜ 3 μm) grain size and 900°C irradiation temperature causing a significant amount of the displacement damage to be absorbed at the grain boundaries. The hardness of neutron irradiated and ion irradiated tungsten is very close: 10.4 GPa and 11.2 GPa respectively, demonstrating the ions are likely well-representing the neutron damage in pure tungsten.
10
Codd, Daniel Shawn. "Concentrated solar power on demand". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67579.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 207-215).
This thesis describes a new concentrating solar power central receiver system with integral thermal storage. Hillside mounted heliostats direct sunlight into a volumetric absorption molten salt pool, which also functions as a single tank assisted thermocline storage system. Concentrated light penetrates the molten salt and is absorbed over a depth of several meters; the molten salt free surface tolerates high irradiance levels, yet remains insensitive to the passage of clouds. Thermal losses to the environment are reduced with a refractory-lined domed roof and a small, closeable aperture. The molten salt and cover provide high and low temperature heat sources that can be optimally used to maximize energy production throughout the day, even when the sun is not shining. Hot salt is extracted from the upper region of the tank and sent through a steam generator, then returned to the bottom of the tank. An insulated barrier plate is positioned vertically within the tank to enhance the natural thermocline which forms and maintain hot and cold salt volumes required for operation. As a result, continuous, high temperature heat extraction is possible even as the average temperature of the salt is declining. Experimental results are presented for sodium-potassium nitrate salt volumetric receivers optically heated with a 10.5 kilowatt, 60-sun solar simulator. Designs, construction details and performance models used to estimate efficiency are presented for megawatt-scale molten salt volumetric receivers capable of operating with low cost nitrate or chloride salt eutectics at temperatures approaching 600 'C and 1000 'C, respectively. The integral storage capabilities of the receiver can be sized according to local needs, thereby enabling power generation on demand.
by Daniel Shawn Codd.
Ph.D.
11
Lembke, Fritiof, e Tarek Penser. "Tidal Power". Thesis, KTH, Maskinkonstruktion (Inst.), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209541.
Testo completoAbstract (sommario):
Tidal power is a relatively new area within renewable energy with great potential in some areas of the world. One of the companies working with this is Minesto, and they have developed a technology called Deep Green that uses a kite that is attached to the seabed to generate electricity. The purpose of this project is to research technologies for production of electricity from tides and under water streams and also to describe the Deep Green technology, compare it to other technologies and propose some suggestions to the current solution. The study is separated into two parts and begins with a research faze on Minesto and other companies that have projects within tidal energy. The other section is a modelling faze where models that describe the Deep Greens movement are made. Forces that the system is exposed to are also calculated for further dimensioning of the components. The research revealed that Minesto has some advantages in comparison to the other companies that were looked at. The largest ones were that Deep Green can produce electricity effectively at low water speeds and that the power plants are relatively light. The Modelling showed that the wing moves closer to the seabed at higher water speeds and that some of the components in the system are over dimensioned and could be designed to be lighter.Tidvattenkraft är ett relativt nytt område inom förnybar energi med stor potential i vissa delar av världen. Ett företag som arbetar med just detta är Minesto som tagit fram en teknologi som heter Deep Green och tagit inspiration från drakflygning för att generera energi från havet. Syftet med projektet är att åt Minesto genomföra en informationssökning om konkurrerande teknologier till Deep Green, att med modeller beskriva Deep Green teknologin samt föreslå förbättringar av den nuvarande lösningen. Studien är indelad i två delar och börjar med informationssökning om Minesto och andra företag som arbetar med tidvattenkraft. Den andra delen är en modelleringsfas där modeller som beskriver Deep Greens rörelse tas fram och även krafter för vidare dimensionering av komponenter i systemet. Informationssökningen visade att Minesto har tydliga fördelar i jämförelse med de andra konkurrenter som undersökts. Framför allt att Deep Green kan producera elektricitet effektivt vid låga vattenhastigheter och att kraftverken är relativt lätta. Modelleringen visade att vingen rör sig närmre botten vid högre vattenhastigheter och att vissa komponenter i systemet är överdimensionerade och skulle kunna göras lättare.
12
Sheu, Elysia J. (Elysia Ja-Zeng). "Hybrid solar-fossil fuel power generation". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78189.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 83-92).
In this thesis, a literature review of hybrid solar-fossil fuel power generation is first given with an emphasis on system integration and evaluation. Hybrid systems are defined as those which use solar energy and fuel simultaneously, thus excluding the viable alternative of solar thermal plants which use fossil fuels as backup. The review is divided into three main sections: performance metrics, the different concentrated solar receiver technologies and their operating conditions, and the different hybridization schemes. In addition, a new linear combination metric for analysis of hybrid systems, which considers trade-off of different metrics at the fleet level, is presented. This metric is also compared to alternative metrics from multi-objective optimization. Some previous work only evaluates the hybrid cycle at a certain point in time, which can be misleading as this evaluation would not take into account certain aspects of hybrid cycle such as fluctuating solar supply. Furthermore, almost all previous work designs the hybrid solar-fossil fuel systems for a certain point in time and then evaluates the performance of the system for an entire year. By not taking into account fluctuating solar supply and selling price of electricity in the design of the system, the best possible annual performance of the hybrid cycle may not be reached. Second, an analysis of solar reforming as the integration method for the hybrid cycle is presented, in particular steam reforming of methane. Two solar reforming systems are analyzed: one with a parabolic trough and the other with a solar tower. From the analysis, it is determined that parabolic troughs are not suitable for steam reforming due to the relatively low operating temperatures. The tower reformer system is integrated with a standard combined cycle, and the design and operation of the hybrid cycle is optimized for highest work output for a fixed fuel input and solar collector area (essentially optimizing for maximum cycle efficiency). A heuristic two step procedure is used for the optimization due to the limitation of the optimizer which cannot simultaneously optimize both design and operation. From the optimization, it is determined that the tower reforming integration method is a promising integration option in that this type of hybrid cycle yields high incremental solar efficiencies and also satisfies the linear combination metric for efficiency and CO₂ emissions (i.e., the analyzed hybrid cycle has a higher efficiency for a fixed CO₂ emissions compared to a linear combination of solar only and fossil fuel only cycles).
by Elysia J. Sheu.
S.M.
13
Kordonowy, David N. (David Nathaniel) 1981. "A power assessment of machining tools". Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/31108.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.Includes bibliographical references (p. 75-76).
Energy conservation is becoming a more important ideal in today's society, due to the increasing awareness of environmental and economic impacts. This project experimentally measures the power consumption, which is related to the energy consumption, of machines in the Laboratory for Manufacturing and Productivity, in order to determine the energy cost of the machines. This project then compares the results found experimentally to the theoretical minimum energy consumption in order to reference the measurements to the ideal energy consumption. Finally, this project attempts to find documentation of these energy costs in order to project the results found experimentally onto machines not physically available for measurement. This project found that the machines in the Laboratory for Manufacturing and Productivity used more energy than was necessary while running, due to the sometimes large amount of power needed to run the idle machines. The specifications given by the machine's manufacturers were adequate to estimate the maximum power requirements. Combining these estimates with the motor properties allowed one to estimate the power requirements of both unloaded operation (while the machine was idle) as well as loaded operation.
by David N. Kordonowy.
S.B.
14
Fay, Sarah Claire. "Power hitting : finding the right implement". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118727.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-71).
Striking a ball with an implement occurs often in sports. Athletes are given a large variety of options to choose from when they select their implements. The motivation for this study was the need for a simple method that athletes can use to choose the implement that will allow them to perform their best. The specific focus of this work is identifying the weight properties an implement should have in order to have the most "powerful" shot. The "power" of a shot is measured by how fast the athlete is able to make the ball move after hitting it (the outgoing ball speed). The particular weight property of interest is the implement's mass moment of inertia about an axis through its handle. Five simple models for how the implement's moment of inertia affect the outgoing ball speed are developed and compared, primarily in a field hockey case study. A new model based on the physiology of muscles proves to be more successful in capturing the behavior observed in real striking of sports balls and is the primary contribution of this study. Overall, the models predict that heavier implements than are currently used would produce more powerful shots. This result is reasonable, as implement's are rarely selected with the sole purpose of hitting power shots. Additional objectives should be incorporated into the model to more broadly aid in an athlete's implement selection process.
by Sarah Claire Fay.
S.M.
15
Kirkby, Nicholas (Nicholas J. ). "Reuse of hybrid car power systems". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98967.
Testo completoAbstract (sommario):
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (page 37).
Used hybrid car power systems are inexpensive and capable of tens of kilowatts of power throughput. This paper documents a process for using the second generation Toyota Prius inverter module to drive a three phase permanent magnet synchronous motor/generator from Ford hybrid vehicle. A lightweight housing and a rotor position sensor for the motor/generator are constructed to allow it to be used outside of the original bulky transaxle. Field oriented control is implemented on a microcontroller which interfaces with the motor/generator and the Prius inverter module. The motor, inverter, and controller are installed on a demonstration vehicle for the purpose of load testing.
by Nicholas Kirkby.
S.B.
16
Taylor, Joshua Adam. "Conic optimization of electric power systems". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67601.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-115).
The electric power grid is recognized as an essential modern infrastructure that poses numerous canonical design and operational problems. Perhaps most critically, the inherently large scale of the power grid and similar systems necessitates fast algorithms. A particular complication distinguishing problems in power systems from those arising in other large infrastructures is the mathematical description of alternating current power flow: it is nonconvex, and thus excludes power systems from many frameworks benefiting from theoretically and practically efficient algorithms. However, advances over the past twenty years in optimization have led to broader classes possessing such algorithms, as well as procedures for transferring nonconvex problem to these classes. In this thesis, we approximate difficult problems in power systems with tractable, conic programs. First, we formulate a new type of NP-hard graph cut arising from undirected multicommodity flow networks. An eigenvalue bound in the form of the Cheeger inequality is proven, which serves as a starting point for deriving semidefinite relaxations. We next apply a lift-and-project type relaxation to transmission system planning. The approach unifies and improves upon existing models based on the DC power flow approximation, and yields new mixed-integer linear, second-order cone, and semidefinite models for the AC case. The AC models are particularly applicable to scenarios in which the DC approximation is not justified, such as the all-electric ship. Lastly, we consider distribution system reconfiguration. By making physically motivated simplifications to the DistFlow equations, we obtain mixed-integer quadratic, quadratically constrained, and second-order cone formulations, which are accurate and efficient enough for near-optimal, real-time application. We test each model on standard benchmark problems, as well as a new benchmark abstracted from a notional shipboard power system. The models accurately approximate the original formulations, while demonstrating the scalability required for application to realistic systems. Collectively, the models provide tangible new tradeoffs between computational efficiency and accuracy for fundamental problems in power systems.
by Joshua Adam Taylor.
Ph.D.
17
Borchard, Philipp Michael. "Thermal and mechanical analysis of high power microwave windows". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/38069.
Testo completo
18
Deng, Jian. "Mechanical Mixing of High Concentration Biomass Slurry". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398872138.
Testo completo
19
Gibbons, Jonathan S. (Jonathan Scott) 1979, e Stephen V. 1982 Samouhos. "Mobile power plants : waste body heat recovery". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32814.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references.
Novel methods to convert waste metabolic heat into useful and useable amounts of electricity were studied. Thermoelectric, magneto hydrodynamic, and piezo-electric energy conversions at the desired scope were evaluated to understand their role and utility in the efficient conversion of waste body heat. The piezo-electric generator holds the most promise for the efficient conversion of waste body heat into electricity. In the future, this same device could be easily extended into a combustion based power plant. An experimental apparatus investigating the use of magneto hydrodynamics was designed, built, and tested. A room temperature liquid inetal was propelled through a magneto hydrodynamic channel of 4 inches by 0.1875 inches at a rate of 10 mL/s. A 2 T induction field was applied within the channel. However, the results of the analysis did not find the magneto hydrodynamic device to be an effective electric generator at the scale tested.
by Jonathan S. Gibbons and Stephen V. Samouhos.
S.B.
20
Yunt, Mehmet 1975. "Steam temperature regulation in fossil power plants". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/89876.
Testo completo
21
Taylor, Joshua Adam. "Uncertainty analysis of power systems using collocation". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45891.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 93-97).
The next-generation all-electric ship represents a class of design and control problems in which the system is too large to approach analytically, and even with many conventional computational techniques. Additionally, numerous environmental interactions and inaccurate system model information make uncertainty a necessary consideration. Characterizing systems under uncertainty is essentially a problem of representing the system as a function over a random space. This can be accomplished by sampling the function, where in the case of the electric ship a "sample" is a simulation with uncertain parameters set according to the location of the sample. For systems on the scale of the electric ship, simulation is expensive, so we seek an accurate representation of the system from a minimal number of simulations. To this end, collocation is employed to compute statistical moments, from which sensitivity can be inferred, and to construct surrogate models with which interpolation can be used to propagate PDF's. These techniques are applied to three large-scale electric ship models. The conventional formulation for the sparse grid, a collocation algorithm, is modified to yield improved performance. Theoretical bounds and computational examples are given to support the modification. A dimension-adaptive collocation algorithm is implemented in an unscented Kalman filter, and improvement over extended Kalman and unscented filters is seen in two examples.
by Joshua Adam Taylor.
S.M.
22
Nguyen, Hung Dinh. "Robust stability assessment for future power systems". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115726.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis. "Due to the condition of the original material, there are unavoidable flaws in this reproduction. Some pages in the original document contain text that is illegible"--Disclaimer Notice page.
Includes bibliographical references (pages 119-128).
Loss of stability in electrical power systems may eventually lead to blackouts which, despite being rare, are extremely costly. However, ensuring system stability is a non-trivial task for several reasons. First, power grids, by nature, are complex nonlinear dynamical systems, so assessing and maintaining system stability is challenging mainly due to the co-existence of multiple equilibria and the lack of global stability. Second, the systems are subject to various sources of uncertainties. For example, the renewable energy injections may vary depending on the weather conditions. Unfortunately, existing security assessment may not be sufficient to verify system stability in the presence of such uncertainties. This thesis focuses on new scalable approaches for robust stability assessment applicable to three main types of stability, i.e., long-term voltage, transient, and small-signal stability. In the first part of this thesis, I develop a novel computationally tractable technique for constructing Optimal Power Flow (OPF) feasibility (convex) subsets. For any inner point of the subset, the power flow problem is guaranteed to have a feasible solution which satisfies all the operational constraints considered in the corresponding OPF. This inner approximation technique is developed based on Brouwer's fixed point theorem as the existence of a solution can be verified through a self-mapping condition. The self-mapping condition along with other operational constraints are incorporated in an optimization problem to find the largest feasible subsets. Such an optimization problem is nonlinear, but any feasible solution will correspond to a valid OPF feasibility estimation. Simulation results tested on several IEEE test cases up to 300 buses show that the estimation covers a substantial fraction of the true feasible set. Next, I introduce another inner approximation technique for estimating an attraction domain of a post-fault equilibrium based on contraction analysis. In particular, I construct a contraction region where the initial conditions are "forgotten", i.e., all trajectories starting from inside this region will exponentially converge to each other. An attraction basin is constructed by inscribing the largest ball in the contraction region. To verify contraction of a Differential-Algebraic Equation (DAE) system, I also show that one can rely on the analysis of extended virtual systems which are reducible to the original one. Moreover, the Jacobians of the synthetic systems can always be expressed in a linear form of state variables because any polynomial system has a quadratic representation. This makes the synthetic system analysis more appropriate for contraction region estimation in a large scale. In the final part of the thesis, I focus on small-signal stability assessment under load dynamic uncertainties. After introducing a generic impedance-based load model which can capture the uncertainty, I propose a new robust small signal (RSS) stability criterion. Semidefinite programming is used to find a structured Lyapunov matrix, and if it exists, the system is provably RSS stable. An important application of the criterion is to characterize operating regions which are safe from Hopf bifurcations. The robust stability assessment techniques developed in this thesis primarily address the needs of a system operator in electrical power systems. The results, however, can be naturally extended to other nonlinear dynamical systems that arise in different fields such as biology, biomedicine, economics, neuron networks, and optimization. As the robust assessment is based on sufficient conditions for stability, there is still room for development on reducing the inevitable conservatism. For example, for OPF feasibility region estimation, an important open question considers what tighter bounds on the nonlinear residual terms one can use instead of box type bounds. Also, for attraction basin problem, finding the optimal norms and metrics which result in the largest contraction domain is an interesting potential research question.
by Hung Dinh Nguyen.
Ph. D.
23
Senga, Masaaki. "Modeling and analysis of power steering systems". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11770.
Testo completo
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Rutberg, Michael J. (Michael Jacob). "Modeling water use at thermoelectric power plants". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74674.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.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. 74-77).
The withdrawal and consumption of water at thermoelectric power plants affects regional ecology and supply security of both water and electricity. The existing field data on US power plant water use, however, is of limited granularity and poor quality, hampering efforts to track industry trends and project future scenarios. Furthermore, there is a need for a common quantitative framework on which to evaluate the effects of various technologies on water use at power plants. To address these deficiencies, Part 1 of this thesis develops an analytical system-level generic model (SGEM) of water use at power plants. The S-GEM applies to fossil, nuclear, geothermal and solar thermal plants, using either steam or combined cycles, and outputs water withdrawal and consumption intensity, in liters per megawatt-hour. Two validations of the S-GEM are presented, one against data from the literature for a variety of generation types, the other against field data from coal plants in South Africa. Part 2 of the thesis then focuses on cooling systems, by far the largest consumers of water in most power plants. The water consumption of different cooling systems is placed on a common quantitative basis, enabling direct comparison of water consumption between cooling system types, and examination of the factors that affect water consumption within each cooling system type. The various cost, performance, and environmental impact tradeoffs associated with once-through, pond, wet tower, dry, and hybrid cooling technologies are qualitatively reviewed. Part 3 examines cooling of concentrating solar power (CSP) plants, which presents particular problems: the plants generate high waste heat loads, are usually located in water-scarce areas, and are typically on the margin of economic viability. A case study is conducted to explore the use of indirect dry cooling with cold-side thermal energy storage, in which cooling water is chilled and stored at night, when ambient temperatures are lower and the plant is inactive, and then used the following day. This approach is shown to hold promise for reducing the capital, operational, and performance costs of dry cooling for CSP.
by Michael J. Rutberg.
S.M.
25
Strawser, Daniel DeWitt. "Development of a lithium hydride powered hydrogen generator for use in long life, low power PEM fuel cell power supplies". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74947.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 87-90).
This thesis studies a hybrid PEM fuel cell system for use in low power, long life sensor networks. PEM fuel cells offer high efficiency and environmental friendliness but have not been widely adopted due to cost, reliability, and the problem of hydrogen storage. This thesis focuses on the problem of hydrogen storage. Lithium hydride is selected for study because of its high hydrogen content and because it produces hydrogen through a chemical reaction with water. Control of the lithium hydride hydrolysis reaction is investigated. Active and passively-controlled hydrogen generators that rely on lithium hydride are designed and experimentally studied. A model is created to explain the system's pressure response. The passive hydrogen generator is experimentally tested in a 2 month benchtop fuel cell experiment. The results of the study suggest that it is possible to design a simple, passive generator that controls the hydrogen pressure at an operating point. However, over longer time periods of 1-3 months, the rate of reaction slows significantly and byproduct formation prevents full utilization of the lithium hydride. These limits complicate the design of a power supply relying on lithium hydride.
by Daniel DeWitt Strawser.
S.M.
26
Larson, Richard Winston. "Disruptive innovation and naval power : strategic and financial implications of unmanned underwater vehicles (UUVs) and long-term underwater power sources". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87959.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 111-121).
The naval warfare environment is rapidly changing. The U.S. Navy is adapting by continuing its blue-water dominance while simultaneously building brown-water capabilities. Unmanned systems, such as unmanned airborne drones, are proving pivotal in facing new battlefield challenges. Unmanned underwater vehicles (UUVs) are emerging as the Navy's seaborne equivalent of the Air Force's drones. Representing a low-end disruptive technology relative to traditional shipborne operations, UUVs are becoming capable of taking on increasingly complex roles, tipping the scales of battlefield entropy. They improve mission outcomes and operate for a fraction of the cost of traditional operations. Furthermore, long-term underwater power sources at currently under development at MIT will extend UUV range and operational endurance by an order of magnitude. Installing these systems will not only allow UUVs to complete new, previously impossible missions, but will also radically decrease costs. I explore the financial and strategic implications of UUVs and long-term underwater power sources to the Navy and its future operations. By examining current naval operations and the ways in which UUVs could complement or replace divers and ships, I identify ways to use UUV technology to reduce risk to human life, decrease costs, and leverage the technology learning curve. I conclude that significant cost savings are immediately available with the widespread use of UUVs, and current research investment levels are inadequate in comparison with the risks and rewards of UUV programs.
by Richard Winston Larson.
S.M.
27
Alsagri, Ali Sulaiman. "Thermoeconomic and Optimization Analysis of Advanced Supercritical Carbon Dioxide Power Cycles in Concentrated Solar Power Application". University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1528816504089412.
Testo completo
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Federspiel, Clifford Conrad. "User-adaptable and minimum-power thermal comfort control". Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13223.
Testo completo
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Walsh, Stephen Michael Ensign. "Microjet impingement cooling of high power-density electronics". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118677.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged student-submitted from PDF version of thesis.
Includes bibliographical references (pages 86-90).
The increasing power density of advanced electronics, and in particular Gallium Nitride (GaN) high electron mobility transistors (HEMTs) in RF power amplifiers, represents a major challenge in thermal management. Reducing the operating temperature, by means of effective cooling, improves both the performance and lifetime of the device. In this work, the high heat transfer capability of microjet impingement was leveraged to bring cooling directly to the backside of the electronic device. Previous experimental studies characterized the effects of geometrical factors, such as diameter, pitch, and standoff, on heat transfer performance. Insights from these studies were used to design a square array of sixteen 100 μm jets and a circular array of nineteen 116 μm jets. These designs were then built using standard silicon micro-fabrication techniques and bonded to an integrated heater, which matched the heat generation profile of a HEMT device. A fully conjugate numerical model of the fluid dynamics and heat transfer in COMSOL Multiphysics allowed for visualization of the fluid flow within the assembly. The model was used to predict heat transfer coefficients of over 250 kW/m²-K, showing strong agreement with correlations in the microjet literature. Integration of the microjet device into a closed flow loop demonstrated modest total flow rates and pressure drops. The microjet performance was then characterized using a free space micro-Raman thermography system with spatial resolution of 1 μm. For the first time, two-dimensional scans of a device under power were taken with jet impingement cooling on the backside. The micro-Raman thermography measurements confirmed heat transfer coefficients of 250 kW/m²-K on a device with a heat flux of 5500 W/cm² and a temperature rise of 46 ± 2 °C. In this thesis, practical concerns including microjet orifice clogging and backside erosion were answered through completion of a 1000-hour extended lifetime test. This thesis provides both numerical and experimental research demonstrating the impact of microjet impingement cooling and high spatial resolution micro-Raman thermography.
by Stephen Michael Walsh.
S.M.
30
Yu, Chien-Ning 1970. "Hierarchical congestion management for a deregulated power industry". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80202.
Testo completo
31
Yu, Suhyoun. "Simple certificate for power distribution network security assessment". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113748.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 53-54).
The integration of volatile renewable energy sources, non-traditional load managements, and unforeseen natural disasters introduce uncertainties that could easily jeopardize the security of power systems. Meanwhile, constructing the real solvable boundary-crucial for contingency analysis, security assessment, and planning network processes-in multidimensional parameter space is burdensome and time consuming; hence there is an urgent need for a tool to identify the security region, or the set of viable injections. This thesis presents fast and reliable inner approximation techniques for solvable boundaries of power distribution systems based on Banach fixed point theorem and Kantorovich theorem. The novel method is in a simple "certificate" form-a single lined inequality condition that involves the system variables and parameters. Our certificate is noniterative, therefore computationally efficient, and the simulation results confirm that the presented approach constructs regions that are sufficiently large for most security-constrained functions. The construction for our "certificates" begins with re-formulating power-flow equations into appropriate forms such that they are applicable to the aforementioned two major theorems. Practical applications of the proposed technique include fast screening tool for feasible injection change, certified solvability margins, and new computationally robust continuation power flow algorithms.
by Suhyoun Yu.
S.M.
32
Alvarez, Guerrero Jose David. "Wind power modeling for a rural desalination project". Thesis, Northern Arizona University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10252090.
Testo completoAbstract (sommario):
The Southwest Navajo Nation (SNN) in northeastern Arizona has to deal with poor water quality from regional wells. The people in the Black Falls area of the SNN, have to haul about 10 gallons per capita per day (gpcd) of potable water for household, driving an average of 30 miles per trip, costing at least $30 per 1,000 gallons of potable water and livestock water at a much greater cost. To put this cost in perspective, the people in nearby Flagstaff Arizona pay $3.85 per 1,000 gallons of potable water. The residents of the Black Falls area lack available, efficient, and affordable electricity or any kind of inter-residence electric infrastructure.
Through an agreement between the University of Arizona (UA) and the U.S. Bureau of Reclamation (Reclamation) a pilot-scale solar energy based desalination system was deployed in the Black Falls area in 2014 with a goal to produce 100 gallons of fresh water per day from brine water pumped from the Coconino Sandstone aquifer of the Little Colorado River basin. The water desalination facility operates as an isolated system, in semi-arid climate (Koppen climate classification BSk), located an elevation of 1,470 m above sea level, with an annual average wind speed of 4.77 m/s at 21.3 m hub height and a solar annual average global horizontal irradiance (GHI) of 5.23 kWh/m2/day. By 2015 the desalination research facility was functioning, powered by solar energy (electric and thermal) and backed-up by a propane gas generator. The technology initially selected for testing was sweeping gas membrane distillation (SGMD), in which water is evaporated across the membrane interface between brine and carrier gas in order to purify the water. Operating experience demonstrated that the solar energy supply was insufficient to produce the desired amount of desalinated water and that associated costs (equipment and operation) were high. Northern Arizona University began working with UA in 2015, and undertook a detailed thermodynamic and energy analysis of the desalination system. The energy analysis reveals that the SGM desalination system at 78.8 L/day (20.8 gal/day) requires 26.8 kWh/day (power of 3.35 kW) of electricity and 85.8 kWh/day of thermal energy (power of 10.7 kW). In addition, this study reveals that the CPV is not capable of providing the required thermal energy and electrical energy (50% and 15% deficits). The deficit of electricity led to exploring wind power. The conducted wind resource assessment for the desalination facility, reveals that a single wind turbine rated at 2.4 kW at a hub height of 21.3 m is able to produce 4.0 MWh of electricity (approximately the 40% of the required electric energy). Four different system design scenarios were explored, three consider using existing equipment and one using new equipment (design from scratch). The system design analysis reveals that adding a wind turbine increases the cost of the electricity. However, the system design analysis reveals that adding a backup generator decreases the cost of the electricity. Finally, this thesis describes that the energy system design from scratch and able to supply electric energy at the lowest cost (0.35 $/kWh) is through a combination of PV (3 kW), CPV (5.2 kW), batteries (6 kWh), converter (4 kW), and a backup generator (3 kW).
33
Mathebula, Muhluri Calvin. "Application of process data reconciliation in power plants". Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25449.
Testo completoAbstract (sommario):
The operation of power plants and chemical processes requires process measurements for optimal operations. Process measurements are essential for plant performance optimization, process monitoring and process control. It is vital to have reliable and accurate process data to achieve process optimization. However, process measurements are inevitably subject to measurement errors. These measurement errors are classified as random and gross errors. Data reconciliation technique is an effective data treatment method that is used in chemical processes to enhance the quality of process data. The purpose of data reconciliation is to reduce random errors to achieve measurements which are as accurate and reliable as possible. Data reconciliation technique uses available process measurements to produce consistent and accurate estimates, so close to the true values that they satisfy model constraints. Further, data reconciliation technique depends on measurement redundancy to perform reconciliation and produce reliable estimates. In addition, data reconciliation can also provide estimates of unmeasured observable variables. Process data reconciliation is not complete without a gross error detection strategy that can effectively detect and eliminate gross errors in measurements. Data reconciliation is applied to linear and nonlinear steady state processes with measured and partially measured variables. Heat exchanger and steam generator models with nonlinear mass and energy constraints are used. The reconciliation process is applied in a feed water flow measurements model to illustrate the applicability of data reconciliation.
34
Hedderwick, Richard Anthony. "Performance evaluation of a solar chimney power plant". Thesis, Stellenbosch : University of Stellenbosch, 2000. http://hdl.handle.net/10019.1/1983.
Testo completoAbstract (sommario):
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2000.A solar chimney power plant consists of a central chimney that is surrounded by a transparent canopy located a few meters above ground level. The ground beneath this canopy or collector as it is known is heated by the solar radiation that is effectively trapped by the collector. This in turn heats the air in the collector, which flows radially inwards towards the chimney. This movement is driven by the difference between the hydrostatic pressure of the air inside- and outside the solar chimney system. The energy is extracted from the air by a turbine driven generator situated at the base of the chimney. The performance of such a solar chimney power plant is evaluated in this study making use of a detailed mathematical model. In this model the relevant discretised energy and draught equations are deduced and solved to determine the performance of a specific plant referred to as the "reference plant". This plant is to be located at a site near Sishen in the Northern Cape in South Africa where meteorological data is available. The performance characteristics of this plant are presented using values from the 21 st of December as an example. These characteristics include the instantaneous and integrated power output, as well as the absorption of the solar radiation of each of the parts of the collector. The air temperatures throughout the plant and the convective heat transfer coefficients in the collector in the region of developing and fully developed flow are presented. The pressure of the air throughout the system is presented as well as the pressure drop over the turbine. Temperature distributions in the ground below the collector are also presented and discussed.
35
Lee, Casey Jane. "Mechanical power in well trained swimmers with a physical impairment". Thesis, Manchester Metropolitan University, 2012. http://e-space.mmu.ac.uk/305119/.
Testo completoAbstract (sommario):
The aims of this thesis were to: 1) develop and validate tests of propulsive force and mechanical power that can be used to monitor British Disability swimmers; and 2) contribute to the development of an objective, evidence-based international classification system for swimmers with a physical impairment. The propulsive force produced by unilateral arm amputee and able-bodied swimmers was assessed during a 30 s fully tethered swim (Chapter 3). It was concluded that as a consequence of their physical impairment, arm amputee swimmers produced significantly lower tether forces than able-bodied swimmers. Due to the limitation of the fully tethered method, an Isokinetic Tethered Swimming (ITS) Ergometer was developed (Chapter 4). To establish the setting in which peak power occurs on the device, external power was calculated at a range of tether speeds (Chapter 5). The results demonstrated that peak power occurred at a tether speed of 50 or 60% of the swimmer’s maximal swimming speed, and peak power was significantly related to the level of the swimmer’s physical impairment (IPC Class). Using the peak power setting, the decline in external power was quantified during a 30 s maximal effort swim (Chapter 6). All swimmers exhibited a decline in external power during the swim; however this decline was not related to the swimmer’s IPC Class. The validity of the movement on the ITS Ergometer was established using electromyography (EMG). The data revealed that muscle activation and recruitment patterns were similar to that of free swimming (Chapter 7). Using EMG the effect of neuromuscular fatigue on the contractile properties of the muscles during a 30 s maximal effort swim was examined (Chapter 8). Of the muscles tested, the muscle which appeared to fatigue the most was different for each swimmer.
36
Kabia, John Amara. "Availability assessment of mixed hydro and diesel power supply system : a case study : Sierra Leone's Bumbuna hydroelectric project and Kingtom Power Station". Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/5526.
Testo completo
37
Stanchak, Kathryn E. "Examining transmission power in minimum capacity underwater acoustic networks". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/59910.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 48).
This paper explores the prospect of reducing the transmission power required to operate links within an underwater acoustic network by minimizing the total capacity of the network while maintaining certain data flow requirements. This is motivated by an approximate model for underwater acoustic transmission power that demonstrates that decreasing the distance between nodes, the capacity of a link between nodes, or both, reduces the power required to send a signal between those nodes. A procedure for determining a minimum-sum capacity network developed by Gomory and Hu in 1961 is applied to several common network topologies including tree, ring, and mesh structures. The approximate model for transmission power, which takes into account the large effects of signal attenuation and noise, is used to evaluate these minimal networks. The networks derived from the Gomory-Hu procedure are shown to require less total transmission power to operate the entire network. In order to maintain the pre-set data flow requirements in the Gomory-Hu network, it is necessary to send information across multiple parallel paths in the network. Results show that because of this extra transmission distance, the networks derived via the Gomory-Hu procedure and their consequent parallel routing schemes are less efficient in terms of a single-transmission from one node to another node in the network than their counterpart networks that operate via a direct-access method, although the transmission power requirements per node are reduced. This parallel routing scheme implies that the Gomory-Hu networks could be beneficial for multi-cast transmission. Results show that applying the Gomory-Hu procedure to networks intended for multi-cast instead of single-cast transmission could be a promising way of increasing the efficiency of the overall network.
by Kathryn E. Stanchak.
S.B.
38
El, Khaja Ragheb Mohamad Fawaz. "Solar-thermal hybridization of Advanced Zero Emissions Power Plants". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74434.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 43-44).
Carbon Dioxide emissions from power production are believed to have significant contributions to the greenhouse effect and global warming. Alternative energy resources, such as solar radiation, may help abate emissions but suffer from high costs of power production and temporal variations. On the other hand, Carbon Capture and Sequestration allows the continued use of fossil fuels without the CO2 emissions but it comes at an energetic penalty. The Advanced Zero Emissions Plant (AZEP) minimizes this energy loss by making use of Ion Transport Membrane (ITM)-based oxy-combustion to reduce the cost of carbon dioxide separation. This work seeks to assess if there are any thermodynamic gains from hybridizing solar-thermal energy with AZEP. The particular focus is hybridizing of the bottoming cycle with supplemental solar heating. A simple model of parabolic solar trough was used to hybridize a model of the AZEP cycle in ASPEN Plus*. Two cycle configurations are studied: the first uses solar parabolic troughs to indirectly vaporize high pressure steam through Therminol and the second uses parabolic troughs to directly preheat the high pressure water stream prior to vaporization. Simulations of the solar vaporizer hybrid by varying the total area of collectors (holding fuel input constant) show an increase of net electric output from 439MW for the non-hybridized AZEP to 533MW with an input solar share of 38.8%. The incremental solar efficiency is found to be around 16% for solar shares of input ranging from 5% to 38.8%. Moreover, simulations of variable solar insolation for collector area of 550,000 m2 , show that incremental solar efficiency increased with solar insolation reaching a plateau around 17%. Simulations of the direct solar preheater, show a net electric output of 501.3 MW for a solar share of 35%, (an incremental solar efficiency of 13.73%). The power generation and hence incremental efficiency is lower than in hybridization with steam vaporization with the same input solar share. Synergy analysis for the steam vaporization hybrid indicates no thermodynamic gains from hybridization.
by Ragheb Mohamad Fawaz El Khaja.
S.B.
39
Qiu, Jin 1974. "An electrothermally-actuated bistable MEMS relay for power applications". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/8002.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. 91-92).
This thesis first develops a bistable mechanism that does not rely on internal stress or hinges for its bistability, which is then combined with transient electrothermal actuation and contact structure to develop a MEMS relay for power switching. The relay components, fabricated by a through etch of a silicon wafer using deep reactive ion etch (DRIE), move laterally in the plane of the wafer. The synthesis, analysis, design, fabrication and testing of the relay are all described in this thesis. The bistable mechanism comprises two parallel cosine curved clamped-clamped beams that are also clamped together at their centers. If designed properly it exhibits a second stable deflected shape that is nearly a mirror image of its as-fabricated shape mirrored through the centerline connecting its clamped ends. Both theoretical and finite-element analyses are applied to the modeling, design and optimization of the force-displacement characteristic of the curved beam mechanism. The analyses results agree well with experimental measurement after accounting for fabrication variations. If fabricated properly, the mechanism is mechanically robust; some mechanisms have been switched between their bistable states one million times without sign of failure. The bistable mechanism is combined with two contacts to form a crossbar relay. The contact structure is designed with flat shape and additional compliance; and proper metalization process is developed for its DRIE etched sidewalls; both contributing to a more reliable and low resistance contact. Because of bistability this relay requires no actuation power in either its on or off states. Therefore, transient electrothermal actuators to switch its states are designed, partially with a mechanical model developed for cantilevers subjected to both lateral and axial forces.
(cont.) These actuators typically require 1-ms 50-V pulses to switch the relay. In the off state, the relay contacts stand off more than 200 V. In the on state the best relay contacts exhibit a total resistance of 60 mfQ and a current carrying capacity of 3 A. The relay can switch at a maximum 5 Hz rate. These characteristics make it a good candidate for power protection applications.
by Jin Qiu.
Ph.D.
40
Turza, Ashley K. "Dense, low-power environmental monitoring for smart energy profiling". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/60206.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 49).
Recent architectural trends have included exploring open space and the extensive use of glass as building material. While the details of these large, light-exposed, open-air environments can be modeled as thermal fluid systems in CFD simulations, the use of dense sensor networks can provide real-time monitoring of a building's airflow and thermal management systems without the need for computationally-intensive theoretical models, and can use this data to inform and advance these models. Sensor networks can provide an accurate picture of the actual conditions of a building and how those conditions can change over time, due to deterioration or external influences. The information gathered from such networks will be critical in determining the energy efficiency of a building. To do this, a sensor network made of two types of sensors, temperature-humidity and airflow, was deployed in the large, glass-enclosed atrium of the recently-completed MIT Media Lab Extension (E14) in late March 2010. Their performance was calibrated, monitored, and the preliminary results analyzed in conjunction with the external weather conditions in the Boston metropolitan area. The results show that while the use of the sensors in monitoring temperature and humidity is successful, the airflow sensors currently require a different solution to solve both the need for low-power consumption and resolution, range, and stability in its measurements.
by Ashley K. Turza.
S.B.
41
Garcia, Jorge David S. M. Massachusetts Institute of Technology. "Sodium chlorate oxygen generation for fuel cell power systems". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112489.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-97).
In this thesis we experimentally investigated the use of sodium chlorate as an oxygen storage medium for use in underwater fuel cell power systems. Research into improving hydrogen storage systems is the primary concern when designing fuel cell systems with access to atmospheric oxygen. However, in an underwater environment, performance of the oxygen storage system cannot be overlooked. Oxygen candles using sodium chlorate offer gravimetric storage densities similar to compressed gas storage while also offering volumetric storage densities greater than both gas and cryogenic liquid oxygen storage. Unfortunately, this technology does not allow for controllable rates of oxygen production and is known to cause fires and occasionally explosions when contaminated with organic materials or exposed to external sources of heat. Though useful as an emergency source of oxygen, sodium chlorate will not be viable for use in power systems until safer and more controllable methods of releasing its oxygen are implemented. During this project we developed a batch method for releasing oxygen from sodium chlorate. Two grams of sodium chlorate with nanoscale cobalt oxide catalyst were loaded into a reaction chamber and heated until decomposition. Afterwards a piston was used to eject the materials from the reaction chamber. This method proved to be safer and more reliable than similar chlorate-based oxygen systems as the primary modes of failure, those associated with the buildup of solid residue at the inlets and exits of the reaction chamber, were removed. Aside from preventing the flow of oxygen to a fuel cell, the over-pressurization caused by these problems could compromise the reaction chamber and potentially result in catastrophic failures. The achieved rate of oxygen production, 0.21 L/min with a heating rate between 25 W and 33 W, was below the target 1.13 L/min needed to operate a 200 W PEM fuel cell. Further assessment of this method will require the use of a more active cobalt oxide catalyst, a system with a larger reaction chamber capable of decomposing increased amounts sodium chlorate per cycle and a reduction in heat losses through the use of improved insulation and thermal isolation techniques.
by Jorge David Garcia.
S.M.
42
Kraemer, Daniel Ph D. Massachusetts Institute of Technology. "Solar thermoelectric power conversion : materials characterization to device demonstration". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103490.
Testo completoAbstract (sommario):
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 268-289).
Meeting the ever growing global energy demand with mostly fossil fuel based energy technologies is not sustainable, pollutes the environment and is the main cause of climate change threatening our planet as we know it. Solar energy technologies are a promising, sustainable and clean alternative due to the vast abundance of sunlight. Thus far, photovoltaic solar cells and concentrated solar power are considered to be the most promising approaches. Solar cells directly convert sunlight into electricity by photon induced electron-hole pair generation. Concentrated solar power captures the sunlight in form of heat which is then converted to electricity by means of a traditional mechanical power block. In this thesis, we explore solar thermoelectric generators (STEGs) as an alternative way to convert sunlight to electricity. Similar to concentrated solar power STEGs capture the sunlight in form of heat. However, the captured heat is directly converted to electricity by means of a thermoelectric generator. This solid-state direct heat-to-electricity conversion significantly simplifies the system, reduces cost and maintenance and enables transient operation and system scalability without affecting the performance. Therefore, STEGs have the potential to be deployed as small scale solar power converters in remote areas and on rooftops and as large scale concentrated solar power plants. While the concept of solar thermoelectric power conversion has been proposed over a century ago, most successful experimental efforts reported in, the literature have been limited to below 1 % for STEGs without optical concentration and to approximately 3 - 5 % with optical concentration. Theoretical STEG performances as modeled and discussed in this thesis predict significantly higher efficiencies. A detailed STEG model is introduced to theoretically investigate various parasitic losses and how to minimize their effect to obtain highest and most realistic performance predictions. Additionally, a methodology to optimize a photovoltaic-thermoelectric hybrid system based on spectral splitting is introduced. The optimization and performance prediction of a STEG is only accurate if the relevant material properties are known with high accuracy. However, typical spectroscopy techniques to determine the optical properties, namely the solar absorptance and infrared emittance, of a solar absorber have shortcomings which can lead to significant errors. Similarly, typical commercial equipment to measure the properties of thermoelectric materials including the Seebeck coefficient, the electrical resistivity and the thermal conductivity are prone to large errors. Therefore, we introduce in this thesis novel experimental techniques to measure all relevant properties with improved accuracies in particular the techniques to measure the total hemispherical emittance of a surface and a material's thermal conductivity. A record-low total hemispherical emittance of 0.13 at 500 °C is demonstrated for an Yttria-stabilized-Zirconia-based cermet solar absorber with solar absorptance of 0.91 and thermal stability up to 600 °C. Furthermore, a method was developed to directly measure the efficiency of a thermoelectric leg. Using this method a record-high thermoelectric efficiency of 8.5 % is demonstrated at a relatively small temperature difference of 225 °C for a novel MgAgSb-based compound with hot-pressed silver contact pads. By increasing the temperature difference to a material's compatible 275 °C a thermoelectric efficiency of 10 % is achievable which, thus far, has only been achieve at almost twice the temperature difference. The third main contribution of this thesis is the experimental demonstration of solar thermoelectric power conversion. A record-high STEG efficiency of 4.6 % is demonstrated at AM1.5G (1 kW/m 2) conditions which is 7 times higher than previously reported best values. The performance improvement is achieved by using a STEG with nano-structured bulk thermoelectric materials, a spectrally-selective solar absorber and taking advantage of large thermal concentrations under a vacuum. Despite the vacuum environment and the use of a low-temperature spectrally-selective solar absorber the optimal hot-junction operating temperature is limited to approximately 200 °C due to increasing thermal radiation heat loss. In order to substantially increase the operating temperature difference and STEG efficiency, larger incident solar power densities are required. Furthermore, the STEG requires segmented thermoelectric legs and a high-temperature stable solar absorber. The optimized STEGs are fabricated and tested at moderate and high optical solar concentration. Efficiencies of close to 8 % at 38 suns and close to 10 % at 211 suns, measured based on the solar flux at the absorber, are demonstrated for a STEG with a spectrally-selective solar absorber. The maximum demonstrated solar-to-electricity CSTEG efficiency is 7.5 %. Furthermore, the performance of a STEG at moderate optical concentration with a high-temperature stable black paint solar absorber and a directionally-selective solar receiver cavity is demonstrated to be comparable to a STEG with a spectrally-selective surface at similar insolation.
by Daniel Kraemer.
Ph. D.
43
Collier, Ian M. "Regenerative braking on bicycles to power LED safety flashers". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32868.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaves 28-29).
This work develops a method for capturing some of the kinetic energy ordinarily lost during braking on bicycles to power LED safety flashers. The system is designed to eliminate: (a) battery changing in popular LED flashers, and (b) the "generator drag" associated with battery-less human-powered bicycle lights and flashers. System sizing, mechanical design considerations, potential end-user factors, and a model for braking frequencies in urban settings are discussed. With the urban commuter cyclist in mind as a potential user of the regenerative braking system, custom direct-pull brake calipers (or "V-Brakes") were designed and manufactured to include both conventional friction pads in addition to a DC motor to be used as a generator for kinetic energy capture. The energy captured by the DC motor during braking is passed through a full wave bridge to a bank of Nickel-Cadmium batteries at an efficiency of 79%. The output of the full wave bridge and the batteries are connected in parallel with a step-down switching voltage regulator, which insulates the LED safety flasher from voltage spikes due to braking at high cycling speeds. The performance of the final prototype was evaluated at cycling speeds ranging from 8 to 19 mph and braking frequencies ranging from 2 to 8 operations/stops per mile of travel.
(cont.) From the mean power flow (charging) into the batteries per unit distance of travel and the power required by LED safety flashers, the effectiveness of the system at each speed and stopping frequency is examined. For cyclists traveling at average speeds of 10 mph or higher, the LED safety flashers can be powered continuously for stopping frequencies of 8 times per mile and semi-continuously (> 50% of the time) for stopping frequencies of at least 4 times per mile. As such, the system is determined to be potentially useful to urban commuter cyclists, who frequently perform braking operations at regularly spaced intersections and traffic signals, and who regularly travel by bicycle in low-light conditions (dawn or dusk), though usually less than 50% of the time.
by Ian M. Collier.
S.B.
44
Ware, Laura M. (Laura Marie). "Design of control for efficiency of AUV power systems". Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74915.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71).
The MIT Rapid Development Group designed and built an internal combustion hybrid recharging system for the REMUS 600 Autonomous Underwater Vehicle (AUV) in collaboration with the MIT Lincoln Laboratory. This power system will recharge the lithium ion battery pack of the REMUS 600 and allow the vehicle to travel for 40 consecutive 12-hour missions without returning to recharge. This study analyzes the optimization of time and fuel efficiency in systems of this type. First, the battery charging scheme for optimal time efficiency was investigated through theoretical simulation of the REMUS battery recharging, based on typical curves for lithium ion battery charging. Secondly, the optimal control system for optimizing fuel efficiency was found by examining behavior in several different engines and predicting behavior in MIT RDG hybrid system's engine. A system was developed to control the throttle of the engine while sensing the voltage coming out of a synchronous rectification bridge. This scheme keeps the throttle above 50% unless the power requirement of the charger drops suddenly. Finally, the control scheme was implemented in software, along with controls for engine starting and shutdown.
by Laura M. Ware.
S.B.
45
Sotiropoulos, Filippos Edward. "Real-time trajectory optimization for excavators by power maximization". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120226.
Testo completoAbstract (sommario):
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 45-46).
In this work an algorithm for controlling the motion of an autonomous excavator arm during excavation is presented. To deal with the challenge, posed by modeling and planning trajectories through soil, a model-free method is proposed which aims at maximally harnessing the capabilities of the excavator by matching its internal characteristics to those of the environment. By maximizing the power output of specific actuators the machine is able to strike a balance between disadvantageous operating conditions where it is either getting stuck in the soil or simply not utilizing its full potential to move soil towards task oriented goals. The real-time optimization, which used methods from extremum seeking control, was implemented in simulation and then on a small scale simulation rig which validated the method. It was shown that power maximization as a strategy of trajectory adaptation for excavation was both well-grounded and feasible.
by Filippos Edward Sotiropoulos.
S.M.
46
Hurwich, Andrew (Andrew B. ). "Power requirements for a rapid-fire projectile toy concept". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45836.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references.
The toy industry holds a large portion of the American consumer market, and new products are in constant demand. A new mechanism for use in children's toys has been proposed to fire small plastic balls at a rate of over four hundred per minute. A portable, small, and safe power system must be developed for this mechanism before it is implemented in new children's products. Power requirements for the device have been estimated based on safety guidelines to be 12 Watts. This rate is feasibly supplied by a manually-compressed pressurized air system similar to systems currently used in watershooting children's toys. Such a system was incorporated into the new mechanism and subsequent tests confirmed this estimate. Test results demonstrated that the quality of air seals and the method of physically activating the mechanism are important areas of focus in next-level prototypes. This paper makes recommendations for improvements in these areas.
by Andrew Hurwich.
S.B.
47
Monaghan, Rory F. D. (Rory Francis Desmond). "Hydrogen storage of energy for small power supply systems". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32361.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 91-92).
Power supply systems for cell phone base stations using hydrogen energy storage, fuel cells or hydrogen-burning generators, and a backup generator could offer an improvement over current power supply systems. Two categories of hydrogen-based power systems were analyzed: Wind-hydrogen systems and peak-shaving hydrogen systems. Modeling of base station requirements and alternative power supply system performance was carried out using MATLAB. Final results for potential alternative systems were compared to those for the current power systems. In the case of the wind- hydrogen systems, results were also compared to those of a wind-battery system. Overall feasibility was judged primarily on the net present cost of the power supply systems. Other considerations included conformity to present regulations. Sensitivity analysis of the wind-hydrogen model was carried out to identify the controlling variables. Numerous parameters were varied over realistic ranges. Important parameters were found to include wind resource, electrolyzer size, distance from electricity grid, price of diesel fuel, and electrolyzer and fuel cell cost. The model verified cell phone industry figures regarding the geographical conditions favorable to diesel genset use. Final results for wind-hydrogen systems suggest that for today's electrolyzer and fuel cell costs, wind-battery-diesel systems are the most suitable power system more than 8km from the existing electricity grid, with an annual average wind speed of 7m/s or more, and where diesel costs more than $2.20/gallon.
(cont.) Thinking to the future, with 20% reduced electrolyzer and fuel cell costs, a wind-fuel cell-diesel system with a 15kW electrolyzer is the most suitable system at locations greater than 8km from the existing electricity grid with an annual average wind speed of 7rn/s or more and total diesel costs greater than $2/gallon. Within 8km the grid, in all cases, grid connection is most suitable. Outside this range, with diesel prices below $2/gallon, a genset only system is most suitable in most cases. Analysis of the peak-shaving hydrogen system suggests that it is not suitable for deployment under any realistic circumstances. Replenishment of hydrogen stores has a substantial power requirement.
by Rory F.D. Monaghan.
S.M.
48
Erol, Umit Levent. "DEVELOPMENT OF A LOWER EXTREMITY EXOSKELETON POWER UNIT". Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1619385500249639.
Testo completo
49
Tolkoff, Samuel William 1973. "Robotics and power measurements of the RoboTuna". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9771.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999.Includes bibliographical references (p. 140-143).
The apparatus in the MIT Testing Tank provides a unique opportunity to study both the physics of unsteady flow control and the engineering complexities involved in constraining a vehicle within the geometry of a fish body. The bulk of the work in this study involves clarifying and solving issues with the mechanical and electrical systems of the RoboTuna. We worked toward making the prototype mechanism a robust laboratory instrument, de vising a strong scientific method, reinforcing existing technology and building apparatus to better visualize and quantify the flow field. As existing data for rigid body and ma.Et drag were sparse we conducted a rigorous study of these values. We streamlined the robot, both physically and computationally, revising the data acquisition hardware and software. Confidence in the accuracy of the sensors, and is a suitable calibration routine, is vital to the research. The robot's eighteen internal sensors had not been calibrated since they were installed. We developed an automated calibration routine for the position and load goad sensors, using the motor encoders and supplied torque to classify the built system. Characteristics of the mechanism and sensor performance are now easily, quickly and routinely monitored. Designing and constructing an extensive system for dye visualization and digital particle image velocimetry, we did preliminary work characterizing the boundary layer of the swimming robot. We compare results gathered from the boundary layer of the swimming robot to the law of the wall and real fish swimming. We conducted experimental swimming efficiency runs focusing on the repeatability of the system and its sensitivity to various measurement errors. We have outlined bounds on the validity of our computations and determined how well the RoboTuna is currently performing. As this work represents a piece in a significant ongoing effort, suggestions for future work are included.
by Samuel William Tolkoff.
S.M.
50
Oliver, Jason Ryan. "A micro-COOLING, HEATING, AND POWER (m-CHP) INSTRUCTIONAL MODULE". MSSTATE, 2005. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11092005-123751/.
Testo completoAbstract (sommario):
Cooling, Heating, and Power (CHP) is an emerging category of energy systems consisting of power generation equipment coupled with thermally activated components. The application of CHP systems to residential and small commercial buildings is known as micro-CHP (m-CHP). This instructional module has been developed to introduce engineering students to m-CHP. In the typical engineering curriculum, a number of courses could contain topics related to m-CHP. Thermodynamics, heat transfer, HVAC, heat and power, thermal systems design, and alternate energy systems courses are appropriate m-CHP topics. The types of material and level of analysis for this range of courses vary. In thermodynamics or heat transfer, basic problems involving a m-CHP flavor are needed, but in an alternate energy systems course much more detail and content would be required. This instructional module contains both lecture material and a compilation of problems/exercises for both m-CHP systems and components.