Swift Heavy Ion Irradiation and Thermal Annealing Induced Modification of Structural, Topographical and Magnetic Properties in Monolayer and Bilayer Films Based on FeNiMoB and Zinc Ferrite

Magnetism and magnetic materials have been playing a lead role in the day to day life of human beings. The human kind owes its gratitude to the ‘lodestone’ meaning ‘leading stone’ which lead to the discovery of nations and the onset of modern civilizations. If it was William Gilbert, who first stated that ‘earth was a giant magnet’, then it was the turn of Faraday who correlated electricity and magnetism. Magnetic materials find innumerable applications in the form of inductors, read and write heads, motors, storage devices, magnetic resonance imaging and fusion reactors. Now the industry of magnetic materials has almost surpassed the semiconductor industry and this speaks volumes about its importance. Extensive research is being carried out by scientists and engineers to remove obsolescence and invent new devices. Though magnetism can be categorized based on the response of an applied magnetic field in to diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic; it is ferrimagnetic, ferromagnetic and antiferromagnetic materials which have potential applications. The present thesis focusses on these materials, their composite structures and different ways and means to modify their properties for useful applications. In the past, metals like Fe, Ni and Co were sought after for various applications though iron was in the forefront because of its cost effectiveness and abundance. Later, alloys based on Fe and Ni were increasingly employed. They were used in magnetic heads and in inductors. Ferrites entered the arena and subsequently most of the newer applications were based on ferrites, a ferrimagnetic material, whose composition can be tuned to tailor the magnetic properties. In the late 1950s a new class of magnetic material emerged on the magnetic horizon and they were fondly known as metallic glasses. They are well known for their soft magnetic properties. They were synthesized in the form of melt spun ribbons and are amorphous in nature and they are projected to replace the crystalline counterparts.

Swift Heavy Ion Irradiation and Thermal Annealing Induced Modification of Structural, Topographical and Magnetic Properties in Monolayer and Bilayer Films Based on FeNiMoB and Zinc Ferrite

Magnetism and magnetic materials have been playing a lead role in the day to day life of human beings. The human kind owes its gratitude to the ‘lodestone’ meaning ‘leading stone’ which lead to the discovery of nations and the onset of modern civilizations. If it was William Gilbert, who first stated that ‘earth was a giant magnet’, then it was the turn of Faraday who correlated electricity and magnetism. Magnetic materials find innumerable applications in the form of inductors, read and write heads, motors, storage devices, magnetic resonance imaging and fusion reactors. Now the industry of magnetic materials has almost surpassed the semiconductor industry and this speaks volumes about its importance. Extensive research is being carried out by scientists and engineers to remove obsolescence and invent new devices. Though magnetism can be categorized based on the response of an applied magnetic field in to diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic and antiferromagnetic; it is ferrimagnetic, ferromagnetic and antiferromagnetic materials which have potential applications. The present thesis focusses on these materials, their composite structures and different ways and means to modify their properties for useful applications.

Editorial

Presented in this bulletin educational innovation that changes the traditional teaching of library and documentation with the inclusion of tools such as computer and support documents: the compact disc, floppy disks, optical media mail. It proposes a contemporary conception of storage and retrieval revolutionizing the traditional world of paper.

Real-time load-side control of electric power systems

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems.

(1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with a single synchronous machine. We then extend our framework to a multi-machine power network, where we consider primary and secondary frequency controls, linear and nonlinear power flow models, and the interactions between generator dynamics and load control.

(2) Two-timescale voltage control: The voltage of a power distribution system must be maintained closely around its nominal value in real time, even in the presence of highly volatile power supply or demand. For this purpose, we jointly control two types of reactive power sources: a capacitor operating at a slow timescale, and a power electronic device, such as a smart inverter or a D-STATCOM, operating at a fast timescale. Their control actions are solved from optimal power flow problems at two timescales. Specifically, the slow-timescale problem is a chance-constrained optimization, which minimizes power loss and regulates the voltage at the current time instant while limiting the probability of future voltage violations due to stochastic changes in power supply or demand. This control framework forms the basis of an optimal sizing problem, which determines the installation capacities of the control devices by minimizing the sum of power loss and capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments show that the proposed sizing and control schemes significantly improve the reliability of voltage control with a moderate increase in cost.

Étude sur les propriétés physicochimiques et électrochimiques des liquides ioniques redox et leur application en tant qu’électrolyte dans les supercapaciteurs

Ce mémoire porte sur les recherches et les développements dans le domaine des électrolytes à base de liquide ionique redox. Une nouvelle famille de liquide ionique redox basée sur le ferrocenylsulfonyl(trifluoromethylsulfonyl) (FcNTf) a été développée et étudiée pour la première fois afin de démontrer le potentiel de ces liquides ioniques dans les dispositifs de stockage d’énergie. En premier lieu, les liquides ioniques redox (RILs) composés de l’anion électroactif et du cation d’alkylimidazolium sont synthétisés et caractérisés. L’impact de la variation des chaînes alkyles du cation sur les propriétés physicochimiques et électrochimiques du RIL a été étudié. À une faible concentration en solution, l’impact du cation a peu d’influence sur l’ensemble des propriétés. Cependant, à haute concentration (>50 % massique) et sans électrolyte de support, la formation de films en oxydation a été observée à l'électrode positive. Ce point est intéressant pour les futures recherches et développements dans le domaine, puisque la variation des chaînes alkyles du cation des liquides ioniques redox et la formation de films lors de l’oxydation du FcNTf est peu connue et comprise en littérature. De plus, l’optimisation des conditions de solution d'électrolyte RIL dans les supercapaciteurs est aussi présentée. En deuxième lieu, la mise en application des RILs dans les supercapaciteurs a été testée. La performance énergétique et le mécanisme d’autodécharge ont été ciblés dans cette étude. En présence de l’électrolyte redox, la contribution des réactions faradaiques permet d'accomplir un gain énergique de 287 % versus les systèmes purement capacitifs. À cause de la formation de film à l’électrode, l’électrolyte redox FcNTf joue un rôle primordial dans la prévention de l’autodécharge versus les liquides ioniques qui étaient connus jusqu’à présent. Finalement, ce mémoire a permis de mieux comprendre les effets structure-propriétés relative aux modifications du cation chez les liquides ioniques redox.

Hybrid power system intelligent operation and protection involving plug-in electric vehicles

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. ^ The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. ^ The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.^

Étude sur les propriétés physicochimiques et électrochimiques des liquides ioniques redox et leur application en tant qu’électrolyte dans les supercapaciteurs

Ce mémoire porte sur les recherches et les développements dans le domaine des électrolytes à base de liquide ionique redox. Une nouvelle famille de liquide ionique redox basée sur le ferrocenylsulfonyl(trifluoromethylsulfonyl) (FcNTf) a été développée et étudiée pour la première fois afin de démontrer le potentiel de ces liquides ioniques dans les dispositifs de stockage d’énergie. En premier lieu, les liquides ioniques redox (RILs) composés de l’anion électroactif et du cation d’alkylimidazolium sont synthétisés et caractérisés. L’impact de la variation des chaînes alkyles du cation sur les propriétés physicochimiques et électrochimiques du RIL a été étudié. À une faible concentration en solution, l’impact du cation a peu d’influence sur l’ensemble des propriétés. Cependant, à haute concentration (>50 % massique) et sans électrolyte de support, la formation de films en oxydation a été observée à l'électrode positive. Ce point est intéressant pour les futures recherches et développements dans le domaine, puisque la variation des chaînes alkyles du cation des liquides ioniques redox et la formation de films lors de l’oxydation du FcNTf est peu connue et comprise en littérature. De plus, l’optimisation des conditions de solution d'électrolyte RIL dans les supercapaciteurs est aussi présentée. En deuxième lieu, la mise en application des RILs dans les supercapaciteurs a été testée. La performance énergétique et le mécanisme d’autodécharge ont été ciblés dans cette étude. En présence de l’électrolyte redox, la contribution des réactions faradaiques permet d'accomplir un gain énergique de 287 % versus les systèmes purement capacitifs. À cause de la formation de film à l’électrode, l’électrolyte redox FcNTf joue un rôle primordial dans la prévention de l’autodécharge versus les liquides ioniques qui étaient connus jusqu’à présent. Finalement, ce mémoire a permis de mieux comprendre les effets structure-propriétés relative aux modifications du cation chez les liquides ioniques redox.

Microwave-assisted synthesis and local analyses of positive insertion electrodes for Li-ion batteries

Efficient energy storage holds the key to reducing waste energy and enabling the use of advanced handheld electronic devices, hydrid electric vehicles and residential energy storage. Recently, Li-ion batteries have been identified and employed as energy storage devices due to their high gravimetric and volumetric energy densities, in comparison to previous technologies. However, more research is required to enhance the efficiency of Li-ion batteries by discovering electrodes with larger electrochemical discharge capacities, while maintaining electrochemical stability. The aims of this study are to develop new microwave-assisted synthesis routes to nanostructured insertion cathodes, which harbor a greater affinity for lithium extraction and insertion than bulk materials. Subsequent to this, state-of-the-art synchrotron based techniques have been employed to understand structural and dynamic behaviour of nanostructured cathode materials during battery cell operation. In this study, microwave-assisted routes to a-LiFePO4, VO2(B), V3O7, H2V3O8 and V4O6(OH)4 have all been developed. Muon spin relaxation has shown that the presence of b-LiFePO4 has a detrimental effect on the lithium diffusion properties of a-LiFePO4, in agreement with first principles calculations. For the first time, a-LiFePO4 nanostructures have been obtained by employing a deep eutectic solvent reaction media showing near theoretical capacity (162 mAh g–1). Studies on VO2(B) have shown that the discharge capacity obtained is linked to the synthesis method. Electrochemical studies of H2V3O8 nanowires have shown outstanding discharge capacities (323 mAh g–1 at 100 mA g–1) and rate capability (180 mAh g–1 at 1 A g–1). The electrochemcial properties of V4O6(OH)4 have been investigated for the first time and show a promising discharge capacity of (180 mAh g–1). Lastly, in situ X-ray absorption spectroscopy has been utilised to track the evolution of the oxidation states in a-LiFePO4, VO2(B) and H2V3O8, and has shown these can all be observed dynamically.

Biomechanical force displacement analysis of strength of fixation of tracker holding devices to bone in computer aided joint replacement

Computer aided joint replacement surgery has become very popular during recent years and is being done in increasing numbers all over the world. The accuracy of the system depends to a major extent, on accurate registration and immobility of the tracker attachment devices to the bone. This study was designed to asses the forces needed to displace the tracker attachment devices in the bone simulators. Bone simulators were used to maintain the uniformity of the bone structure during the study. The fixation devices tested were 3mm diameter self drilling, self tapping threaded pin, 4mm diameter self tapping cortical threaded pin, 5mm diameter self tapping cancellous threaded pin and a triplanar fixation device ‘ortholock’ used with three 3mm pins. All the devices were tested for pull out, translational and rotational forces in unicortical and bicortical fixation modes. Also tested was the normal bang strength and forces generated by leaning on the devices. The forces required to produce translation increased with the increasing diameter of the pins. These were 105N, 185N, and 225N for the unicortical fixations and 130N, 200N, 225N for the bicortical fixations for 3mm, 4mm and 5mm diameter pins respectively. The forces required to pull out the pins were 1475N, 1650N, 2050N for the unicortical, 1020N, 3044N and 3042N for the bicortical fixated 3mm, 4mm and 5mm diameter pins. The ortholock translational and pull out strength was tested to 900N and 920N respectively and still it did not fail. Rotatory forces required to displace the tracker on pins was to the magnitude of 30N before failure. The ortholock device had rotational forces applied up to 135N and still did not fail. The manual leaning forces and the sudden bang forces generated were of the magnitude of 210N and 150N respectively. The strength of the fixation pins increases with increasing diameter from three to five mm for the translational forces. There is no significant difference in pull out forces of four mm and five mm diameter pins though it is more that the three mm diameter pins. This is because of the failure of material at that stage rather than the fixation device. The rotatory forces required to displace the tracker are very small and much less that that can be produced by the surgeon or assistants in single pins. Although the ortholock device was tested to 135N in rotation without failing, one has to be very careful not to put any forces during the operation on the tracker devices to ensure the accuracy of the procedure.

Estimating benefits of energy storage for aggregate storage applications in electricity distribution networks in Queensland

Electric Energy Storage (EES) is considered as one of the promising options for reducing the need for costly upgrades in distribution networks in Queensland (QLD). However, It is expected, the full potential for storage for distribution upgrade deferral cannot be fully realized due to high cost of EES. On the other hand, EES used for distribution deferral application can support a variety of complementary storage applications such as energy price arbitrage, time of use (TOU) energy cost reduction, wholesale electricity market ancillary services, and transmission upgrade deferral. Aggregation of benefits of these complementary storage applications would have the potential for increasing the amount of EES that may be financially attractive to defer distribution network augmentation in QLD. In this context, this paper analyzes distribution upgrade deferral, energy price arbitrage, TOU energy cost reduction, and integrated solar PV-storage benefits of EES devices in QLD.

Battery energy storage systems to improve power system frequency response

Battery energy storage systems (BESS) are becoming feasible to provide system frequency support due to recent developments in technologies and plummeting cost. Adequate response of these devices becomes critical as the penetration of the renewable energy sources increases in the power system. This paper proposes effective use of BESS to improve system frequency performance. The optimal capacity and the operation scheme of BESS for frequency regulation are obtained using two staged optimization process. Furthermore, the effectiveness of BESS for improving the system frequency response is verified using dynamic simulations.

A simple low-cost electrical switching analyzer for I-V characterization of switching samples and devices

The phenomena of nonlinear I-V behavior and electrical switching find extensive applications in power control, information storage, oscillators, etc. The study of I-V characteristics and switching parameters is necessary for the proper application of switching materials and devices. In the present work, a simple low-cost electrical switching analyzer has been developed for the measurement of the electrical characteristics of switching materials and devices. The system developed consists of a microcontroller-based excitation source and a high-speed data acquisition system. The design details of the excitation source, its interface with the high-speed data acquisition system and personal computer, and the details of the application software developed for automated measurements are described. Typical I-V characteristics and switching curves obtained with the system developed are also presented to illustrate the capability of the instrument developed.

Scalable processes for fabricating non-volatile memory devices using self-assembled 2D arrays of gold nanoparticles as charge storage nodes

We propose robust and scalable processes for the fabrication of floating gate devices using ordered arrays of 7 nm size gold nanoparticles as charge storage nodes. The proposed strategy can be readily adapted for fabricating next generation (sub-20 nm node) non-volatile memory devices.