Developing A Medium-Voltage Three-Phase Current Compensator Using Modular Switching Positions

The objective of this thesis is to present the context, application, theory, design, construction, and testing of a proposed solution to unbalanced current loading on three-phase four-wire systems. This solution, known as the Medium-Voltage Unbalanced Current Static Compensator or MV-UCSC, is designed to recirculate currents between the three phases of adistribution system. Through this redistribution of the currents negative- and zero-sequence current components are eliminated and a balanced load is seen upstream from the point of installation. The MV-UCSC as it operates in the distribution system is presented followed by its effect on traditional compensation equipment. The construction of the MV-UCSC as well as 13.8 kV simulations are then shown. Development of the switching positions required by the MVUCSC is then given followed by a variation on this switching position with the intent to reduce part count. Finally, the testing the 13.8 kV three-phase four-wire, neutral-point-clamped, elevenlevel, flying-capacitor-based MV-UCSC connected directly to the grid is presented

A Surgical Navigation and Endoscope Holder Integrated System for Sinus Surgery

In this paper, we developed an integrated system, which consists of an augmented reality-based surgical navigation system (ARSNS) and an endoscope-holder system (EHS) to reduce complications such as blindness, cerebrospinal fluid leak and to solve a constraint on hand movement of surgeons during sinus surgery. The proposed system provides following main functions: warning system, automatic transparency adjustment, magnetic brakes, and counter-balancing mechanism. In addition, the system compensates for AR error which increases with the rotation of the scope cylinder. For the evaluation of ARSNS and EHS, the phantom experiments were performed with surgeons. Through the experiments, surgeons found the proposed system will be effective in performing sinus surgery

Argobots: A Lightweight Low-Level Threading and Tasking Framework

In the past few decades, a number of user-level threading and tasking models have been proposed in the literature to address the shortcomings of OS-level threads, primarily with respect to cost and flexibility. Current state-of-the-art user-level threading and tasking models, however, either are too specific to applications or architectures or are not as powerful or flexible. In this paper, we present Argobots, a lightweight, low-level threading and tasking framework that is designed as a portable and performant substrate for high-level programming models or runtime systems. Argobots offers a carefully designed execution model that balances generality of functionality with providing a rich set of controls to allow specialization by end users or high-level programming models. We describe the design, implementation, and performance characterization of Argobots and present integrations with three high-level models: OpenMP, MPI, and colocated I/O services. Evaluations show that (1) Argobots, while providing richer capabilities, is competitive with existing simpler generic threading runtimes; (2) our OpenMP runtime offers more efficient interoperability capabilities than production OpenMP runtimes do; (3) when MPI interoperates with Argobots instead of Pthreads, it enjoys reduced synchronization costs and better latency-hiding capabilities; and (4) I/O services with Argobots reduce interference with colocated applications while achieving performance competitive with that of a Pthreads approach

Supercapatteries as High-Performance Electrochemical Energy Storage Devices

Abstract: The development of novel electrochemical energy storage (EES) technologies to enhance the performance of EES devices in terms of energy capacity, power capability and cycling life is urgently needed. To address this need, supercapatteries are being developed as innovative hybrid EES devices that can combine the merits of rechargeable batteries with the merits of supercapacitors into one device. Based on these developments, this review will present various aspects of supercapatteries ranging from charge storage mechanisms to material selection including electrode and electrolyte materials. In addition, strategies to pair different types of electrode materials will be discussed and proposed, including the bipolar stacking of multiple supercapattery cells internally connected in series to enhance the energy density of stacks by reducing the number of bipolar plates. Furthermore, challenges for this stack design will also be discussed together with recent progress on bipolar plates. Graphic Abstract: Supercapattery is an innovated hybrid electrochemical energy storage (EES) device that combines the merit of rechargeable battery and supercapacitor characteristics into one device. This article reviews supercapatteries from the charge storage mechanisms to the selection of materials including the materials of electrodes and electrolytes. Strategies for pairing different kinds of electrode materials and device engineering are discussed.[Figure not available: see fulltext.

Polymeric Microsensors for Intraoperative Contact Pressure Measurement

Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays using biocompatible polymer substrates and dielectrics while preserving industry-standard microfabrication processing for micron-level resolution. An array of sensors for real-time measurement of pressure profiles is the long-term goal of this research. A custom design using capacitive-based sensors is an excellent selection for such measurement, giving high spatial resolution across the sensing surface and high load resolution for pressures applied normal to that surface while operating at low power

Redox-Enhanced Electrochemical Capacitors: Electrolyte Design and Device Engineering

Electrochemical energy storage is increasingly important as the world decarbonizes and electrifies. Research in this area requires compromise between properties that are often mutually exclusive, including power, energy, lifetime, efficiency, operating temperature, safety, and cost. Electric double layer capacitors (EDLCs) exhibit high power and outstanding cycle life compared to secondary batteries, but have low specific energy, limiting applications. Redox-enhanced electrochemical capacitors (redox ECs) are a class of augmented electric double-layer capacitors utilizing reversible redox reactions of soluble redox couples in the electrolyte to add faradaic charge storage. These systems offer increased energy density, efficient power delivery, and simple construction. We study a range of redox-active electrolytes to clarify operating mechanisms and formalize design rules for high-performance. Our investigations focus on dual-redox ECs, which attain higher energy density by employing a pair of distinct redox couples, with each operating at a different electrode. Simplicity is important both in terms of the mechanistic aspects of the electrochemical redox chemistry and for system cost considerations. A single ionic molecular entity that intrinsically delivers both distinct redox couples is preferable over two separate redox-active electrolytes. In this context, we have identified specific viologen bromide salts as particularly promising aqueous redox-active electrolytes for dual-redox ECs. While charging, Br– is oxidized to Br3– at the positive electrode and the viologen dication (V2+) is reduced to the stable monocation radical (V+•) at the negative electrode. The reverse processes occur during discharge, providing a high-capacity faradaic discharge plateau and attaining an energy density of ~20 Wh/L. The viologen bromide system shows unusually high Coulombic efficiency and low self-discharge rates for an aqueous redox-EC. This was initially attributed to strong adsorption of the Br3– and V+• to the activated carbon electrodes, but a more detailed analysis confirms that the behavior is due to two electroprecipitation mechanisms. In these mechanisms, each ion acts as a charge-storing redox couple at one electrode and as a complexing agent at the other electrode. The processes are highly reversible and cells show negligible capacity fade even after 20,000 cycles. The devices use conventional activated carbon electrodes, and because crossover is not a concern and self-discharge is suppressed, a simple inexpensive cellulose separator is sufficient and more costly ion-selective membranes are not required. Based on our understanding of solid complexation in redox ECs, we studied in detail the confinement of charged redox species in porous electrodes with liquid-to-solid phase transitions to mitigate self-discharge. We demonstrate that in addition to viologens, tetrabutylammonium cations induce reversible solid complexation of Br2/Br3–. This mechanism slows cross-diffusion of Br3–, stabilizes the reactive bromine generated during charging, and can be broadly used as a positive electrode to balance the capacity of a wide variety of pseudocapacitive or battery-type negative electrodes. In the final component of this work we consider the challenges of scaling up these systems for practical application. We address corrosion of metallic current collectors, which is a common device design challenge for high-power aqueous electrochemical energy storage devices, by designing a bipolar pouch cell using electrochemically stable carbon-polymer composite current collectors. In order to show the versatility of this approach, we construct a high-power redox EC/battery hybrid using a zinc metal anode and an activated carbon cathode with tetrabutylammonium-complexed bromide catholyte. This system achieves excellent power and energy performance, with negligible capacity degradation over more than 3000 cycles.Throughout the dissertation we compare the performance and properties of our dual redox ECs to those of the current state-of-the-art conventional energy storage systems and other redox-enhanced energy storage systems and we close with comments on economic analysis and the future of redox enhanced electrochemical capacitors

Advanced Ultra-High Speed Motor for Drilling

Three (3) designs have been made for two sizes, 6.91 cm (2.72 inch) and 4.29 cm (1.69 inch) outer diameters, of a patented inverted configured Permanent Magnet Synchronous Machines (PMSM) electric motor specifically for drilling at ultra-high rotational speeds (10,000 rpm) and that can utilize advanced drilling methods. Benefits of these motors are stackable power sections, full control (speed and direction) of downhole motors, flow hydraulics independent of motor operation, application of advanced drilling methods (water jetting and abrasive slurry jetting), and the ability of signal/power electric wires through motor(s). Key features of the final designed motors are: fixed non-rotating shaft with stator coils attached; rotating housing with permanent magnet (PM) rotor attached; bit attached to rotating housing; internal channel(s) in a nonrotating shaft; electric components that are hydrostatically isolated from high internal pressure circulating fluids ('muds') by static metal to metal seals; liquid filled motor with smoothed features for minimized turbulence in the motor during operation; and new inverted coated metal-metal hydrodynamic bearings and seals. PMSM, Induction and Switched Reluctance Machines (SRM), all pulse modulated, were considered, but PMSM were determined to provide the highest power density for the shortest motors. Both radial and axial electric PMSM driven motors were designed with axial designs deemed more rugged for ultra-high speed, drilling applications. The 6.91 cm (2.72 inch) OD axial inverted motor can generate 4.18KW (5.61 Hp) power at 10,000 rpm with a 4 Nm (2.95 ft-lbs) of torque for every 30.48 cm (12 inches) of power section. The 6.91 cm (2.72 inch) OD radial inverted motor can generate 5.03 KW (6.74 Hp) with 4.8 Nm (3.54 ft-lb) torque at 10,000 rpm for every 30.48 cm (12 inches) of power section. The 4.29 cm (1.69 inch) OD radial inverted motor can generate 2.56 KW (3.43 Hp) power with 2.44 Nm (1.8 ft-lb) torque at full speed 10,000 rpm for every 30.48 cm (12 inches) of power section. Operating conditions are 300 voltage AC at the motor leads. Power voltage losses in the cables/wirelines to the motor(s) are expected to be about 10% for 5000 feet carrying 2 amperes. Higher voltages and better insulators can lower these losses and carry more amperes. Cutting elements for such high tip velocities are currently not available, consequently these motors will not be built at this time. However, 7.62 cm (3 inch) OD, low speed, PMSM radial electric motors based on this project design are being built under a 2006 Oklahoma Center for the Advancement of Science and Technology 'proof of concept' grant

Development of an FPGA and MCU based Stack-able Processing platform incorporated with on-board compute module for Real-time processing applications

The focus of this thesis is to develop an FPGA and MCU-based stackable processing platform incorporated with an on-board computer module for real-time processing applications. The goal is to deliver a compact-sized hardware platform with extensible capabilities to provide high-speed, parallel computing with low power consumption. This hardware platform is named ioNeurons and consists of three module types: processing modules, sensing modules, and interface modules. The ioNeurons ecosystem design is based on combining individual strengths into highly adaptable and powerful solutions. The processing modules are stackable in no particular order, allowing the ability to match multiple modules’ individual capabilities to the project’s needs. Developers can assign tasks to multiple processing modules according to the different real-time requirements. The implementation of a small-scale quadrotor helicopter is introduced as an application of this hardware platform