Photoactivated fluorescence from individual silver nanoclusters ranging in size from 2 8 atoms has been demonstrated at room temperature. The optical properties of such clusters are far superior to those of fluorescence dyes with absorption cross sections ~50 times stronger than those of even the best organic dyes. The strong oscillator strengths produced from such nanoclusters has been shown to yield comparable enhancement factors in the surface-enhanced Raman spectroscopy (SERS) process to those observed in the presence of a plasmon- supporting nanoparticle. Raman transitions are in fact so strong that antistokes scattering is also observable on a single molecule (SM) level marking the first true demonstration of SM-SERS to date. Capable of generating true scaffold specific Raman scattering on the single molecule level, the combination of fluorescence from the small nanoclusters and strong observed Raman signals in the absence of a nanoparticle strongly indicate a chemical or charge transfer SERS enhancement mechanism.

This research is aimed to study the storage tank design parameters effects on the efficiency of the large solar hot water system. Detailed CFD simulation for the storage tank coupled with TRNSYS program simulation for the entire solar hot water system will be performed to study the system performance under various thermal stratification baffles design for the storage tank. The study is made for three representative cities of Taiwan by input their typical-meteorological-year data (TMY data). The results indicate the performance of a large solar hot water system can be significantly improved with proper designed thermal stratification baffles in the storage tank.

Donor cells for nuclear transfer are usually prepared by the culture of fresh tissue. However, animal carcasses are sometimes frozen without cryoprotectants and if it were possible to obtain live cells from carcasses (tissue) preserved in this manner, it could be very beneficial in nuclear transfer cloning of trophy or extinct animals. This study tested the hypothesis that tissue samples of skin, muscle, and oral mucosa could be cryopreserved without cryoprotection. The tissue samples were taken from euthanized goats and placed into a -20°C freezer for varying lengths of time. The samples were thawed by two different methods. One method was in 37°C water bath and the other was on ice, thawing to room temperature from 1°C to 25°C. The samples were then processed and placed into an incubator to evaluate cell growth. Skin samples frozen for up to 34 days obtained cell growth to confluency and the cells were then cryopreserved with cryoprotectant. The cells were able to tolerate the potentially lethal effects of ice nucleation and dehydration brought about by ice formation and colligative factors. Although this method of cryopreservation has been shown to yield growth of cells that might be useful for nuclear transfer cloning, it is not the recommended method to cryopreserve tissues if cryoprotectants are available or if only short term storage is needed. These procedures would be especially useful when a precious animal dies unexpectedly and cryoprotectant is not available and the sample can not be processed before 10 days.

Power systems on modern commercial transportation systems are moving to more electric based equipment, thus improving the reliability of the overall system. Electrical equipment on such systems will include some loads that require very high power for short periods of time, on the order of a few seconds, especially during acceleration and deceleration. The current approach to solving this problem is sizing the electrical grid for peak power, rather than the average. A method to efficiently store and discharge the pulsed power is necessary to eliminate the cost and weight of oversized generation equipment to support the pulsed power needs of these applications. Highspeed Flywheel Energy Storage Systems (FESS) are effectively capable of filling the niche of short duration, high cycle life applications where batteries and ultra capacitors are not usable. In order to have an efficient high-speed FESS, performing three important steps towards the design of the overall system are extremely vital. These steps are modeling, analysis and control of the FESS that are thoroughly investigated in this dissertation. This dissertation establishes a comprehensive analysis of a high-speed FESS in steady state and transient operations. To do so, an accurate model for the complete FESS is derived. State space averaging approach is used to develop DC and small-signal AC models of the system. These models effectively simplify analysis of the FESS and give a strong physical intuition to the complete system. In addition, they result in saving time and money by avoiding time consuming simulations performed by expensive packages, such as Simulink, PSIM, etc. In the next step, two important factors affecting operation of the Permanent Magnet Synchronous Machine (PMSM) implemented in the high-speed FESS are investigated in detail and outline a proper control strategy to achieve the required performance by the system. Next, a novel design algorithm developed by S.P. Bhattacharyya is used to design the control system. The algorithm has been implemented to a motor drive system, for the first time, in this work. Development of the complete set of the current- and speed-loop proportional-integral controller gains stabilizing the system is the result of this implementation. In the last part of the dissertation, based on the information and data achieved from the analysis and simulations, two parts of the FESS, inverter/rectifier and external inductor, are designed and the former one is manufactured. To verify the validity and feasibility of the proposed controller, several simulations and experimental results on a laboratory prototype are presented.

Non-volatile memories are an emerging storage technology with wide applica- tions in many important areas. This study focuses on new storage techniques for flash memories and phase-change memories. Flash memories are currently the most widely used type of non-volatile memory, and phase-change memories (PCMs) are the most promising candidate for the next-generation non-volatile memories. Like magnetic recording and optical recording, flash memories and PCMs have their own distinct properties, which introduce very interesting data storage problems. They include error correction, cell programming and other coding problems that affect the reliability and efficiency of data storage. Solutions to these problems can signifi- cantly improve the longevity and performance of the storage systems based on flash memories and PCMs. In this work, we study several new techniques for data storage in flash memories and PCMs. First, we study new types of error-correcting codes for flash memories – called error scrubbing codes –that correct errors by only increasing cell levels. Error scrubbing codes can correct errors without the costly block erasure operations, and we show how they can outperform conventional error-correcting codes. Next, we study the programming strategies for flash memory cells, and present an adaptive algorithm that optimizes the expected precision of cell programming. We then study data storage in PCMs, where thermal interference is a major challenge for data reliability. We present two new coding techniques that reduce thermal interference, and study their storage capacities and code constructions.

Utilizing flywheels to store and reuse energy from regenerative braking on locomotives is a new technology being developed in the Vibration Control and Electromechanics Lab at Texas A&M. This thesis focuses on the motion analysis of a locomotive mounted energy storage flywheel system for a variety of support motion inputs. Two input cases, sinusoidal floor input and ramp input, are analyzed in different sections. Simulation results and methods of ensuring the operating success of the flywheel system are provided at the end of each section. Section 1 introduces the problem and method being used to study the vibration under different circumstances. Section 2 analyzes the response of the flywheel system to sinusoidal floor input given by Ahmadian and Venezia 2000. Natural frequency and transmissibility of the system are utilized to explain the simulation results carried out in the frequency domain. It is found that the motion differences between flywheels(rotors) and magnetic bearings(stators) are guaranteed to be small. Section 3 emulates the locomotive traversing a bump with 1:150 slope. Simulation shows that catcher(backup) bearings are needed to limit the vibration of rotors through a bump. It is also found that gyroscopic effect causes problems in vibration isolation. Section 4 explores de-levitation method and installation of gimbals as possible remedies to this problem. Finally, a summary of simulation results from different input cases is made.

The primary objective of this work is to identify the optimal bioethanol production plant capacity and configuration based on currently available technology for all the processing sections involved. To effect this study, a systematic method is utilized which involves the development of a superstructure for the overall technology selection, process simulation and model regression of each processing step as well as equipment costing and overall economic evaluation. The developed optimization model is also designed to incorporate various biomass feedstocks as well as realistic maximum equipment sizing thereby ensuring pragmatism of the work. For this study, the criterion for optimization is minimum ethanol price. The secondary and more interesting aim of this work was to develop a systematic method for evaluating the economics of biomass storage due to seasonal availabilities. In essence, a mathematical model was developed to link seasonal availabilities with plant capacity with subsequent integration into the original model developed. Similarly, the criterion for optimization is minimum ethanol price. The results of this work reveal that the optimal bioethanol production plant capacity is ~2800 MT biomass/day utilizing Ammonia Fiber Explosion pretreatment technology and corn stover as the preferred biomass feedstock. This configuration provides a minimum ethanol price of $1.96/gal. Results also show that this optimal pretreatment choice has a relatively high sensitivity to chemical cost thereby increasing the risk of implementation. Secondary to this optimal selection was lime pretreatment using switchgrass which showed a fairly stable sensitivity to market chemical cost. For the storage economics evaluation, results indicated that biomass storage is not economical beyond a plant capacity of ~98 MMgal/yr with an average biomass shortage period of 3 months. The study also showed that for storage to be economical at all plant capacities, the storage scheme employed should be general open air land use with a corresponding biomass loss rate as defined in the study of 0.5 percent per month.

Rainwater harvesting (RWH) is a method of capturing rainfall from a catchment surface and storing it for later use. Though it has been around for thousands of years, its popularity and use has been increasing in recent years and water quality within RWH systems has become a concern. Water temperature is a parameter of water quality and storage container color and shading affect this temperature. Four different colors and three different shadings were applied to twelve rainwater storage barrels. Water temperature of these barrels was measured over twenty weeks during a Texas summer. During the initial ANOVA model, it was determined that the color and shade variables had an interaction and thus both together had an effect on the water temperature. Though the individual treatment variables could not be analyzed and compared statistically, the trends showed that light colors and higher shading caused lower water temperatures in the storage containers. Also, the color had more pronounced effect than shading on water temperature inside the barrels.

Thermal energy storage systems, precisely latent thermal energy storage (LTES), are systems capable of recovering and storing thermal energy from waste processes, including hot exhaust gases out of combustion engines, or even renewable sources of energy like solar energy. LTES rely on phase change materials (PCMs) to store a significant amount of thermal energy in a relatively small volume. With limited volume and at almost constant temperature, they are capable of storing a large amount of thermal energy, mainly latent energy. Studies of LTES systems have focused primarily on system and process optimization including transient behavior as well as field performance. A major drawback in the development of the use of PCM in LTES has been the low thermal conductivity characteristic of most PCMs. Thus, there is a need to enhance heat transfer using reliable techniques, with the goal of reducing the charging and discharging times of PCM in LTES systems. Some approaches that have been studied in the past include use of finned tubes, insertion of metal matrix into PCM, and microencapsulation of PCM. The performance of TES configurations in forced convection have been characterized using Reynolds numbers (Re), and Stefan numbers (Ste) of the heat transfer fluid (HTF) for different enhancement techniques. The goal of this study is to experimentally investigate the effectiveness of corrugated PCM panels with high surface-to-volume ratio in forced convection as a function of HTF mass flow rate, charging temperature, and flow direction through a corrugated TES unit. The PCM (octadecane) has been segmented using sealed corrugated panels containing several channels immersed in the HTF stream. With this approach, the author expects that the charging and discharging times will be substantially reduced due to the high surface-to-volume ratio of the PCM panel for heat transfer. Of the three conditions examined, the HTF direction influenced the charging and discharging times the most with significant reductions in these times observed when the HTF flow direction through the TES was upwards. Buoyancy effects, observed at high Stefan numbers, were important during the charging (melting) process and greatly influenced the temperature profiles along each channel. Results indicate that the devised TES is more effective than some other TES systems in the literature.

Diese Diplomarbeit betrachtet, inwiefern sich mit Hilfe freier Software große Speicherkapazitäten über ein Netzwerk verfügbar machen lassen. Dabei wird neben der Untersuchung existierender Lösungen und Ansätze eine Eigenentwicklung auf Basis des in Linux enthaltenen Network-Block-Device vorgestellt.