Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains xvi, 184 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 145-147).

Thesis (Ph. D.)--Missouri University of Science and Technology, 2008. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 1, 2009) Includes bibliographical references (p. 117-124).

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xiii, 150 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 140-144).

Examensarbetet har utförts på företaget Röbäcks Sweden AB, som arbetar inom betongindustrin. Röbäcks mål är att sälja kompletta betongfabriker med tillhörande styrsystem som kan vara mobila eller stationära. Utöver att producera betongfabriker tillverkar Röbäcks det mesta inom mekanisk konstruktion till kundens förutsättningar.   Röbäcks har varit i kontakt med en kund i Norge som behöver en ny skopelevator till sin betongfabrik, eftersom den nuvarande elevatorn börjar falla isär. Kunden vill nu att Röbäcks ska ta fram ett förslag på en skopelevator som passar deras fabrik. Kundens önskemål är en skopelevator som transporterar 300  ballast till en ballastficka vid en höjd på 20 meter. Elevatorn skall även vara utrustad med inspektionsluckor som underlättar eventuell service. Skopelevatorns uppgift är att transportera ballast från marknivå till en ballastficka där betongtillverkningsprocessen sätts igång.  Syftet med examensarbetet är att ta fram ett designförslag för en skopelevator med användning av ”computer-aided design” (CAD) med mjukvaran Inventor. Designförslaget skall innehålla konstruktions- och ritningsunderlag. Utifrån tidigare konstruktioner och en bild av den nuvarande fabriken kunde elevatorn anpassas efter kundens förutsättningar.   Projektet har resulterat i ett designförslag för en skopelevator som drivs av en 30 kW vinkelväxelmotor. Elevatorn är uppbyggd i flera sektioner som består av en bottensektion, fem mittsektioner och en översektion. Grundtanken bakom sektionerna är att skopelevatorn skall vara moduluppbyggd och att antalet mittsektioner avgör elevatorns höjd vilket underlättar vid montering och demontering. En utmärkande detalj i konstruktionen är den rundade botten som gör att skoporna succesivt skrapar upp spill, detta i sin tur ger ekonomiska fördelar för kunden som undviker svinn.   All tillverkning av skopelevatorn är planerad att ske i Röbäcks verkstad, förutom några få komponenter som beställs från externa företag. Alla komponenter sammanfogas sedan till en färdig skopelevator i Röbäcks verkstad. / This project has been performed at the company Röbäcks Sweden AB, a supplier in the concrete industry. The main goal for Röbäcks is to sell complete concrete factories with associated control systems that can be both mobile and stationary. In addidition, Röbäcks manufactures mechanical parts to the customers conditions.  Röbäcks has been in contact with a customer in Norway, who needs a new bucket elevator for a concrete factory, because the current elevator is starting to fall apart. The customer wants Röbäcks to come up with a design proposal for a new, improved bucket elevator suitable for the factory. The customer’s request is an elevator that can transport 300  of ballast to an inlet 20 meters above the ground. The bucket elevator is also equipped with inspection hatches to facilitate maintenances work. The task of the bucket elevator is to transport ballast from ground level to a ballast intake, where the concrete manufacturing process starts.  The purpose of the exam project is to create a design proposal for a bucket elevator using “computer-aided design” (CAD) with the software Inventor. The proposal should include all necessary design details, materials choices and associated CAD drawings. Based on previous constructions and a picture of the current factory, the elevator design is adapted to the customers conditions.  The project has resulted in a design proposal for a bucket elevator that is driven by a 30 kW bevel gear motor. The elevator is built in several sections consisting of one bottom section, five middle sections and one upper section. The idea behind the sections is a modular bucket elevator, where the number of middle sections determines the height of the elevator. This facilitates assembly and disassembly. A distinctive detail in the construction is the rounded bottom section, which makes the buckets scope up the spill. The feature will provide economic benefits for the customer and help to avoid wasting ballast material.  Apart from a few components that need to be ordered from external companies, the entire production process of the elevator can take place at Röbäck's workshop.

No description available.

Five new single-stage power factor correction (PFC) techniques are developed for single-phase applications. These converters are: Integrated single-stage PFC converters, voltage source charge pump power factor correction (VS-CPPFC) converters, current source CPPFC converters, combined voltage source current source (VSCS) CPPFC converters, and continuous input current (CIC) CPPFC converters. Integrated single-stage PFC converters are first developed, which combine the PFC converter with a DC/DC converter into a single-stage converter. DC bus voltage stress at light load for the single-stage PFC converters are analyzed. DC bus voltage feedback concept is proposed to reduce the DC bus voltage stress at light load. The principle of operations of proposed converters are presented, implemented and evaluated. The experimental results verify the theoretical analysis. VS-CPPFC technique use a capacitor in series with a high frequency voltage source to achieve the PFC function. In this way, the input inductor is eliminated. VS-CPPFC AC/DC converters are developed, and their performance is evaluated. VS-CPPFC electronic ballasts with and without dimming function are also presented. The average lamp current control with duty ratio modulation is developed so that the lamp operates in constant power with a low crest factor over the line variation. The experimental results verify the CPPFC concept. CS-CPPFC technique employs a capacitor in parallel with a high frequency current source to obtain the PFC function. The unity power factor condition and principle of operation are analyzed. By doing so, the switch has less switching current stress, and deals only with the resonant inductor current. Design considerations and experimental results of the CS-CPPFC electronic ballast are presented. VSCS-CPPFC technique integrates the VS-CPPFC with the CS-CPPFC converters. The circuit derivation, unity power factor condition and design considerations are presented. The developed VSCS-CPPFC converters has constant lamp operation, low crest factor with a high power factor even without any feedback control. CIC-CPPFC technique is developed by inserting a small inductor in series with the line rectifier for the conceptual VS-CPPFC, CS-CPPFC and VSCS-CPPFC circuits. The circuit derivation and its unity power factor condition are discussed. The input current can be designed to be continuous, and a small line input filter can be used. The circulating current in the resonant tank and the switching current stress are minimized. The average lamp current control with switching frequency modulation is developed, so the developed electronic ballast operates in constant power, low crest factor. The developed CIC-CPPFC electronic ballast has features of low line input current harmonics, constant lamp power, low crest factor, continuous input current, low DC bus voltage stress, small circulating current and switching current stress over a wide range of line input voltage. / Ph. D.

In the past, radial-mode piezoelectric transformer (Transoner) design has been difficult due to the complex interaction between the physical and electrical circuit characteristics. Prior to a design procedure, experimental design by Face Electronics, LC led to a sample that could fit a ballast application enabling zero voltage switching (ZVS) for the semiconductors without the use of any external inductance. In the ballast circuit, the piezoelectric transformer is used to replace the conventional inductor-capacitor resonant tank saving valuable space and expense. With ballast in mind, a design process has been developed in this thesis to optimize radial mode transformers to fit specifically tailored applications. The graphical process described, allows the engineer to design in the capability of zero voltage switching for a half-bridge drive while simultaneously providing highly efficient performance. The problem of mounting a piezoelectric transformer to a circuit board has also been addressed in this thesis. A thermally conductive mounting technique has been developed which can enhance both the power capability and reliability of circuits utilizing these devices. / Master of Science

The High-Intensity-Discharge Lamps (HID), consisting of a broad range of gas discharge lamps, are notable for their high luminous efficacy, good color rendering, and long life. Metal halide lamps have the best combination of the above properties and are considered the most ideal light sources. Recently, there has been an emerging demand to replace the conventional halogen headlamps with the newly introduced small-wattage metal halide HID lamps. However, this lamp demands a highly efficient ballast and very complex control circuitry that can achieve fast turn-on and different regulation modes during the lamp start-up process. Due to the complex lamp v-i profile and timing control requirements, control circuit built with conventional analog control is unavoidably cumbersome. With the unparalleled flexibility and programmability, digital control shows more advantages in this application. An automotive HID ballast with digital controller is developed to demonstrate the feasibility of the digital control along with some key issues in digital controller selection and design. Results show that the microcontroller-based HID ballast can successfully realize the required control functions and achieve a smooth turn-on process and a fast turn-on time of 8 seconds. One of the major issues of ballast design is the ballast/HID lamp system stability, which originates from the lamp negative incremental impedance. The lamp small-signal model is presented with simulation and measurements. The negative incremental impedance is attributed to a RHP zero in the small-signal model. A new analysis approach, impedance ratio criterion, is proposed to analyze the system stability. With this approach, it clearly shows how the control configurations and converter and control design affect the system stability. The results can provide guidance and be easily used in control configuration selection and converter and control design. Analysis shows that ballast based on PWM converter without inner current loop is unstable and with inner current loop can stabilized the system. This is the reason why for a microcontroller-based ballast system the inner current loop has to be used. HID lamp has its special acoustic resonance problem and thus a low-frequency unregulated full-bridge is used following the front-end DC/DC converter. To prevent from lamp re-igniting during each bridge commutation, a minimum current changing slope has to be guaranteed. In order to help design the converter, the ballast/lamp re-ignition analysis is presented. With this analysis, it shows that the output capacitance has to be small enough to ensure adequate current slope during zero crossing. Though some approximation is used to simplify the analysis, the results can provide qualitative guidance in the ballast design. / Master of Science

Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004. / Includes bibliographical references (p. 53). / Nimitz class aircraft carriers possess an inherent list to starboard that their list control systems (LCS) are typically unable to correct while under Combat Load Conditions. As a result, it has become necessary to use fresh water ballast in a number of inner bottom voids and damage control voids to augment the LCS. Maintaining liquid ballast in damage control voids is unacceptable, as it reduces the design counter flooding capability of the ship, and thus reduces ship survivability. In order to restore the ships operational flexibility and achieve the necessary/desired list correction, this study determines the effect of adding solid ballast to a series of voids/tanks identified on the 2nd, 4th, and 8th decks. Based on ballast density, tank location and capacity, ease of ballast installation, minor tank structural modifications, and a decision making cost analysis, solid ballast was determined to be the most advantageous for use in correcting the inherent list on the Nimitz class aircraft carriers. Fresh water ballast was also examined as a possible alternative, but not as extensively due to the large quantity of water required and its limited ability to achieve a list correction. Nimitz class aircraft carriers currently have an average list of 1.5 degrees and a KG of 47 feet. / (cont.) Since their allowable KG cannot exceed 48.5 feet, the average service life allowance (SLA) for KG is approximately 1.5 feet. This study shows that by adding approximately 400 Iton of solid ballast, list can be corrected by 1.5 degrees with only a 0.1 percent increase in KG. Thus, to permanently fix the average Nimitz class aircraft carrier starboard list, there would be a 0.05 foot increase in KG, which in all cases is within the SLA. Additionally, this study shows that this 1.5 degree list correction can be accomplished at a low cost of approximately $1,200 per Iton. Considering the reduction in operational constraints and the benefits to ship survivability, this is truly an inexpensive proposition. / by Dianna Wolfson. / S.M. / Nav.E.

Recent regulation mandates that ships conduct mid ocean ballast water exchange (BWE) prior to discharging foreign ballast in territorial waters of Australia, the U.S. and elsewhere. The enforcement of ballast water exchange legislation is undermined, however, by a lack of sensitive and reliable methods for verifying compliance. One way to assess compliance is to compare the concentrations of chemical tracers in ballast tanks with their known distributions in the open ocean. In this work, dissolved organic matter and trace elements are investigated as potential tracers of mid-ocean ballast water exchange on commercial voyages in the North Pacific and Atlantic Oceans. The optical properties of chromophoric dissolved organic matter (CDOM) are frequently used as tracers of water masses in bays and estuaries. Characterization of the underlying fluorescence spectra in seawater dissolved organic matter was performed using parallel factor analysis, allowing the identification of at least nine independently varying fluorescent components present in varying concentrations in the ocean and in ballast water. Two of the humic components were terrestrial in origin and their signals could be traced in the open ocean (Pacific and Atlantic) at levels of approximately 1.5% of riverine concentrations. One humic terrestrial component was sufficient for predicting the coastal vs. oceanic source of most ballast water samples, suggesting that single and dual channel fluorometers could be optimized for verifying ballast water exchange. Barium, manganese and phosphorus were also investigated as potential tracers. Measurements of Ba and P obtained via engine-cooling pipes on commercial vessels were consistent with previous oceanographic measurements. While Ba behaved conservatively in ballast water, concentrations of phosphorus fluctuated and Mn was removed in ballast tanks over time. Ba and P demonstrated considerable promise as ballast water tracers, exhibiting predictable concentrations in exchanged ballast tanks, given a priori knowledge of the ocean (Atlantic versus Pacific) in which BWE was performed.