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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Oil, Oil, Everywhere: Environmental and Human Impacts of Oil Extraction in the Niger Delta

Pitkin, Julia 01 May 2013 (has links)
Oil extraction in Nigeria has caused extensive environmental degradation and health problems in many Nigerian communities, particularly in the ecologically sensitive Niger Delta where nearly all of the oil extraction takes place. The reasons for this are complex and have roots in Nigeria’s colonial past. The Nigerian economy is largely reliant on its petroleum resources which, in conjunction with governmental corruption and high international demand for Nigerian oil, has created a system where environmental externalities are largely ignored. Multinational oil companies with little stake in the development and environment of Nigeria are responsible for most of the extraction projects and subsequent environmental damage. However, the Nigerian federal government has failed to effectively regulate these projects. Communities in the Niger Delta bear nearly all of the environmental burden of oil extraction, but see very little of the economic benefits. The main environmental impacts of oil extraction are oil spills, land use change, and gas flaring. Oil spills are very common in the Niger Delta. Cleanup efforts are often inadequate, resulting in loss of delicate ecosystems as well as fisheries and farmland. Large tracts of rainforest and mangrove ecosystems have been cleared or degraded by the oil extraction process. Nigeria flares more gas per barrel of oil extracted than any other country in the world, contributing to global warming and creating serious health hazards for communities located near gas flares. Diversification of the Nigerian economy would help to alleviate many of the factors that lead to environmental degradation, including the dependence of the government on oil revenues, high unemployment, and rampant oil theft. Curbing government corruption is also vital to effective regulation of oil extraction. International consumers can help Nigeria head towards a less petroleum-driven future through an increased awareness of the origins of their oil and pressure on the Nigerian federal government and the multinational oil companies to extract oil more conscientiously or even to discontinue oil extraction. But most importantly, the solution to Nigeria’s economic concerns must ultimately come from Nigerians as international influence has been a major contributor to the environmental degradation in the first place.
22

Smart Grid Functionality of a PV-Energy Storage System

Damnjanovic, Nenad 01 January 2011 (has links)
Renewable Energy will be the key to preserving the Earth's remaining resources and continuing this surge of technological progress that we have experienced this past century. New philosophies of how/when/where energy should be consumed and produced are attempting to improve upon the current grid infrastructure. The massive advancement in communications, renewable and control systems will allow this new-age electric grid to maximize its efficiency while reducing cost. Renewable, "green" energy is now at the forefront of innovation. As the world population increases, there will be a need to free ourselves from natural resources as much as possible. Advanced Energy Storage Systems (AESS) will play a vital and large role in this new-age infrastructure. Because renewable energy is not constant (aside from hydroelectricity), this energy needs to be conserved and used at appropriate times. The Sustainable Electric Energy Delivery System (SEEDS) project features an AESS made from Lithium-ion phosphate (LiFeP04) and a Photovoltaic (PV) source connected to the grid. Every current technology has different parameters, efficiency, charge/discharge rates, lifespan, etc. The current Li-FeP04 system will be used as an example and a model. This project acts as a pilot project for future large scale smart grid endeavors. This thesis is written in conjunction with the SEEDS project and will outline and discuss in detail the findings. For the PV system, the performance is analyzed. For the storage system, the round-trip efficiency (measured) and life cycle are broken down. The thesis concludes with a capacity sizing estimation of the storage system which is based on the renewable energy source (solar).
23

Synthesis and Characterization of Nanocomposites for Electrochemical Capacitors

Alvi, Farah 01 January 2012 (has links)
Presently there are deep concerns over the environmental consequences and the consumption of non-renewable energy sources, with the accelerated greenhouse effect, triggered enormous interest in the use of renewable energy sources e.g., solar, hydropower, wind and geothermal. However the intermittent nature of harvesting renewable energy sources has recently gained considerable attention in the alternative reliable, cost effective, and environmentally friendly energy storage devices. The supercapacitor and lithium ion batteries are considered more efficient electrical energy storage devices than conventional energy storage systems. Both devices have many useful and important applications; they could be an excellent source for high power and high energy density, especially in portable electronic devices and Electrical Vehicles (EVs) or Hybrid Electrical Vehicles (HEVs). In order to make the efficient usage of these stationary energy storage devices, state of the art research on new and advanced electrode materials is highly needed. The aim of this dissertation is to investigate the scope of graphene/metal oxide-conducting polymer nanocomposites electrodes for light weight, high power density and wider voltage window supercapacitor devices. The facile chemical polymerization approach was used to synthesize the aromatic and heterocyclic conducting polymer nanocomposites. For aromatic nanocomposites, several materials were synthesized includes ZnO-PANI, ZnO/G-PANI,RuO2-PANI and G-PANI. Subsequently these materials have been characterized by physical, structural techniques e.g Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Xray-Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). In addition to material characterization the prepared material was also characterized by electrochemical measurements using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chrono potentiometry for supercapacitor electrodes. Since graphene is a two-dimensional single-atom-thick sp2 hybridized carbon structure due to its extraordinary characteristic, high electrical conductivity, chemical stability and large theoretical surface area (over 2600 m2 g−1) has gained immense interest in the future generation of renewable energy devices. Therefore, among all aromatic based nanocomposites, the Graphene-Polyaniline (G-PANI) rendered promisingly high specific capacitance around 440 F/g with the excellent cyclic stability. The higher specific capacitance of G-PANI might be due to the high conductivity and superior electrochemical properties of graphene in G-PANI nanocomposites. However, besides the G-PANI, other aromatic nanocomposites e.g., RuO2-PANI, ZnO-PANI and G/ZnO-PANI also showed the potential of low cost and flexible supercapacitor electrodes with the reasonably good specific capacitance as 360 F/g, 300 F/g, and 275 F/g. We have further investigated the role of conductivity by adding different amount of graphene in G-PANI nanocomposites to optimize device performance with the specific capacitance and columbic efficiency of 440 F/g and 90% respectively.Further the other important parameters, relate with the electrode thickness, type of electrolytes, concentration of electrolytes and the effect of the solvent has also been studied to achieve the overall performance and reliability of the device. Moreover, in order to have the comprehensive study of conducting polymer besides the aromatic conducting polymer the heterocyclic polymers e.g., polythiophene and poly (3, 4-ethylenedioxythiophenes) (PEDOT) nanocomposites were studied at length to evaluate their role for the cost effective, large surface area and flexible green energy storage devices and has shown great prospects for commercial application. Therefore, G-Cps nanocomposites have proved to be a promising electrode material choice to facilitate the ionic diffusion and contact of the electrolytes to improve the specific capacitance and performance of the device.
24

Assessment of Methods to Manipulate Thermal Emission and Evaluate the Quality of Thermal Radiation for Direct Energy Conversion

Wijewardane, Samantha 01 January 2012 (has links)
ABSTRACT Control of spectral thermal emission from surfaces may be desirable in some energy related applications, such as nano-scale antenna energy conversion and thermophotovoltaic conversion. There are a number of methods, from commercially available paints to advanced surface gratings that can be used to modify the thermal emission from a surface. To find out the proper emission controlling technique for a given energy conversion method all the surface emission controlling methods are comprehensively reviewed regarding the emission control capabilities and the range of possible applications. Radiation with high degree of coherence can be emitted using advanced surface emission controlling techniques. The entropy of the thermal radiation, and therefore the exergy, is a function of the degree of coherence. A methodology is presented to calculate the exergy of partially coherent wave fields so that the radiation fields can be evaluated based on exergy. This exergy method is extended to develop a rigorous evaluation criterion for thermal emission controlling methods used in frequency dependent energy conversion applications. To demonstrate these developed criteria using actual data, a surface plasmon emitter is designed and fabricated. Also, possible ways of improving the emitter performance and the research needed to be carryout to fabricate cost effective emitters are described.
25

Synthesis and Investigations of type I and II clathrates of Group 14

Blosser, Michael 01 January 2013 (has links)
Clathrates are a class of new materials that have an open-framework structure that allows guest atoms or molecules to be enclosed inside of their polyhedral framework. Varying the number, weight, and size of the guest species in a particular framework allows one to alter the physical properties of the clathrate. This relationship enables one to further the fundamental understanding of the physics and chemistry of the clathrate structure and use this knowledge to "tune" certain properties. This "tunability" of inorganic clathrates is of great interest as it allows one to optimize their physical properties; making them promising candidates for a range of applications such as thermoelectric, optoelectronic, and superconductivity. In this study, new synthesis methods of type I and II clathrates of group 14 are introduced, along with two new compositions of type I clathrates. A new synthesis method used to produce single crystal and microcrystalline Na8Si46 and Na24Si136 clathrates by the spark plasma sintering technique is introduced. Microcrystalline type I Na8Si46 and type II Na24Si136 are also selectively synthesized with no phase impurity of the other type using the low temperature ionic liquid method. In addition, the synthesis of microcrystalline Na8Ge3Si38 and single crystal Ba2Cs6Ga8Sn38 type I clathrates are presented for the first time.
26

Hydrogen Storage in Hypercrosslinked Polystyrene and Li-Mg-N-H Complex Hydride

Demirocak, Dervis Emre 01 January 2013 (has links)
In this dissertation, hydrogen storage enhancement in hypercrosslinked polystyrene, effects of single walled carbon nanotubes (SWCNTs) supported ruthenium (Ru) catalyst on the kinetics and ammonia suppression in the LiNH2-MgH2 complex hydride system and the accuracy of hydrogen storage measurements are investigated in detail. High surface area physisorption materials are of interest for room temperature hydrogen storage enhancement by spillover. Six different commercially available hypercrosslinked polystyrenes are screened by considering the specific surface area, average pore size, pore volume, and adsorption enthalpy. MN270 is selected mainly due to its high surface area and narrow pores for investigation of the spillover enhancement at room temperature. Two different platinum (Pt) doped MN270 samples are prepared by wet impregnation (MN270-6wt%Pt) and bridge building technique (MN270-bridged) with an average Pt particle size of 3.9 and 9.9nm, respectively, as obtained from X-ray diffraction analysis. Pt doping altered the surface property of MN270, and reduced the nitrogen and hydrogen uptake at 77 K and 1 atm due to pore blocking. The room temperature hydrogen uptake at 100 atm demonstrated a 10% enhancement for the MN270-bridged (0.36 wt. %) compared to the pristine MN270 (0.32 wt. %), but did not show any enhancement for the MN270-6wt%Pt under the same conditions. The hydrogen uptake of MN270-bridged has little value for practical applications; however, it showed the effectiveness of the bridge building technique. The LiNH2 - MgH2 (2:1.1) complex metal hydride system (Li-Mg-N-H), which is prepared by high energy ball milling, is investigated in terms of the hydrogen ab/desorption kinetics and the concomitant NH3 emission levels. By selecting more intense ball milling parameters, the hydrogen ab/desorption kinetics were improved and the NH3 emission reduced. However, it is shown that NH3 emission cannot be completely eliminated by ball milling. The hydrogen desorption kinetics of the Li-Mg-N-H system is much faster than the absorption kinetics at a specific T and P, but the desorption kinetics degraded considerably over a number of cycles as opposed to the stabilized absorption kinetics. Furthermore, SWCNTs and 20 wt. % Ru doped SWCNTs (SWCNT-20Ru) are utilized as catalysts to study their effects on NH3 emission and kinetics characteristics of the Li-Mg-N-H system. The SWCNT doped sample did not show any kinetics improvement, whereas the SWCNT-20Ru doped sample showed similar kinetics performance as that of the base sample. More importantly, the presence of SWCNT increased the NH3 emission as compared to the base sample. On the other hand, SWCNT-20Ru doping reduced the NH3 emission compared to the SWCNT doping, but did not eliminate it completely. As revealed from the mass spectrometry signals, the SWCNT-20Ru catalyst starts to decompose NH3 at a temperature as low as 200°C. However, an optimal catalyst still needs to be developed by fine tuning the Ru particle size and the SWCNT structural properties to maximize its effectiveness to suppress NH3 release in the Li-Mg-N-H system. The design of a volumetric measurement apparatus is studied by means of an uncertainty analysis to provide guidelines for optimum hydrogen sorption measurements. The reservoir volume should be as small as possible (i.e., 10 cc) to minimize the uncertainty. In addition, the sample mass loading has a profound effect on the uncertainty and the optimum loading is a function of the sample's intrinsic storage capacity. In general, the higher the sample mass loading the lower is the uncertainty, regardless of any other parameters. In cases where the material to be tested is not available in gram quantities, the use of high accuracy pressure and temperature transducers significantly mitigates the uncertainty in the sample's hydrogen uptake. Above all, the thermal equilibration time is an important parameter for high accuracy measurements and needs to be taken into consideration at the start of the measurements. Based on computational analysis, a 5 min wait time is required for achieving thermal equilibrium when the instrument enclosure temperature is different than the ambient temperature.
27

A Study on the Optimization of Dye-Sensitized Solar Cells

Khan, Md Imran 01 January 2013 (has links)
Considering biocompatibility, the Dye Sensitized Solar Cell (DSC) based on titanium dioxide should play a major role in the future of solar energy. In this ongoing study, different components and ambient process conditions for the fabrication of were investigated. Titanium dioxide substrate thickness and morphology was found to have a direct impact on the cell efficiency. Scanning Electron Microscopy (SEM) was used to investigate the TiO2 nanostructure. Different chemical treatments and electrolytes were also explored towards optimizing the cell performance. A group of porphyrin based organic dyes were synthesized and evaluated. Standard solar cell characterization techniques such as current-voltage and spectral response measurements were employed to evaluate the cell performance.
28

Effect of Solids Retention Time on the Denitrification Potential of Anaerobically Digested Swine Waste

Kinyua, Maureen Njoki 01 January 2013 (has links)
Three continuously stirred tank reactors (CSTR) were operated in semi continuous mode treating swine waste using anaerobic digestion. The reactors were used to test the effect of solid retention time (SRT) on CH4 yield, total ammonia nitrogen (TAN) concentrations, % volatile solids (VS), chemical oxygen demand (COD) and volatile fatty acids (VFA) removal, readily biodegradable COD concentration and the denitrification potential for the effluent in a biological nutrient removal (BNR) system. During Phase I of the study, the three reactors were operated at the same 28 day SRT for 16 weeks. SRTs were then changed during the 12 week Phase II period. The SRTs studied were 14, 21 and 28 days, with the same organic loading rate (OLR) of 1.88 ± 0.2 kg VS/ m3-day. The reactor with the lowest SRT (14 days) had the highest VS and VFA removal at 73.6 and 67.6% and lowest TAN concentration at 0.78 g NH4+-N/L, followed by the 21 day and 28 day reactors. This was likely due to the fast microbial growth rates and substrate utilization rates in this reactor compared with the other two. The 14 day reactor had the highest CH4 yield at 0.33 m3CH4/kg VS added and readily biodegradable COD concentration at 0.93 COD/L. The variations in CH4 yield and readily biodegradable COD concentrations between the three reactors were not statistically significant. Denitrification potential for the reactors was 1.20, 0.73 and 0.56 g COD/g N for 14, 21 and 28 day reactors, respectively, and the differences were statistically significant. None of the reactors achieved a denitrification potential of 5 g COD/g N, the amount required to use effluent of anaerobically digested swine waste as an internal carbon source in a BNR. This was attributed to operating conditions such as freezing and thawing of the raw swine waste that maximized CH4 yield and lowered the readily biodegradable COD concentration. In addition the 14 day reactor had low TAN concentrations thus increasing the denitrification potential of the centrate from that reactor.
29

Application and Characterization of Self-Assembled Monolayers In Hybrid Electronic Systems

Celesin, Michael Enoch 01 January 2013 (has links)
In this study, we explore ultra-thin insulators of organic and inorganic composition and their potential role as high-speed rectifiers. Typical applications for these structures include IR sensing, chemical detection, high speed logic circuits, and MEMS enhancements. While there are many elements in the functional group required to create a rectifying antenna (rectenna), the primary thrust of this work is on the rectifier element itself. To achieve these research goals, a very good understanding of quantum tunneling was required to model the underlying phenomenon of charge conduction. The development of a multi-variable optimization routine for tunneling prediction was required. MATLAB was selected as the programming language for this application because of its flexibility and relative ease of use for simulation purposes. Modeling of physical processes, control of electromechanical systems, and simulation of ion implantation were also to be undertaken. To advance the process science, a lithographic mask set was made which utilized the information gleaned from the theoretical simulations and initial basic experiments to create a number of diode test structures. This came to include the creation of generations of mask sets--each optimizing various parameters including testability, alignment, contact area, device density, and process ease. Following this work, a complete toolset for the creation of "soft" contact top metals was required and needed to be developed. Ultra-flat substrates were needed to improve device reliability and measurement consistency. The final phase of research included measurement and characterization of the resultant structures. Basic DC electrical characterization of the organic monolayers would be accomplished using metal probes. Statistical studies of reliability and process yield could then easily be carried out. The rectification ratio (ratio of forward over reverse current at a given voltage magnitude) was found to be a reliable indicator of diode performance in the low frequency ranges. This would mean writing additional code in MATLAB to assist in the automatic analysis for the acquired IV curves. Progression to AC / RF measurements of tunneling performance was to be accomplished using relatively low frequencies (below 100 MHz). Finally, the organic films themselves would be studied for consistency, impedance characteristics, incidence of defects, and thickness by a variety of metrology techniques. This project resulted in a number of advances to the state-of-the-art in nanofabrication using organic monolayers. A very detailed review of the state of alkanethiol research was presented and submitted for publication. A single pot technique was developed to softly deposit metal nanoparticles onto a charged surface with a high degree of control. A temporary contact method using pure, sub-cooled gallium liquid metal was used to probe organic monolayers and plot IV curves with better understanding of surface states than before. An inkjet printer solution was devised for top contact printing which involved the development and production of a work-up free insulator ink which is water soluble and printable to resolutions of about 25 um. Localized selective chemical crosslinking was found to reduce printed ink solubility following deposition. Future work will likely include additional exploration of crosslinkable Langmuir-Blodgett films as MIM insulators. Stability and testing will hinge on the fabrication of enclosures or packages for environmental isolation.
30

Control of Smart Building Using Advanced SCADA

Samuel, Vivin Thomas 01 January 2013 (has links)
ABSTRACT For complete control of the building, a proper SCADA implementation and the optimization strategy has to be build. For better communication and efficiency a proper channel between the Communication protocol and SCADA has to be designed. This paper concentrate mainly between the communication protocol, and the SCADA implementation, for a better optimization and energy savings is derived to large scale industrial buildings. The communication channel used in order to completely control the building remotely from a distant place. For an efficient result we consider the temperature values and the power ratings of the equipment so that while controlling the equipment, we are setting a threshold values for FDD technique implementation. Building management system became a vital source for any building to maintain it and for safety purpose. Smart buildings, refers to various distinct features, where the complete automation system, office building controls, data center controls. ELC's are used to communicate the load values of the building to the remote server from a far location with the help of an Ethernet communication channel. Based on the demand fluctuation and the peak voltage, the loads operate differently increasing the consumption rate thus results in the increase in the annual consumption bill. In modern days, saving energy and reducing the consumption bill is most essential for any building for a better and long operation. The equipment - monitored regularly and optimization strategy is implemented for cost reduction automation system. Thus results in the reduction of annual cost reduction and load lifetime increase.

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