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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.
1

Efficient Energy Transfer for Wireless Devices

Westlund, Arvid, Bernberg, Oskar January 2012 (has links)
This project is intended to findsuitable circuit architecture forefficient power transmission where thepower supply is low.Two circuits will be built. The firstwill receive high AC which correspondsto the voltage created in a piezoelement once subjected to stress fromfoot steps It will deliver 3.3DC.The second circuit will receive low ACwhich will represent voltage receivedfrom a wireless transfer.Due to a failing high voltage powersupply the second circuit was never putto practice. The idea was to send a wavefile through an OP-amplifier to simulatethe voltage from the piezo element. Thevoltage was then rectified and convertedto 3.3DC.Circuit 2 was tested with a frequencygenerator as power supply. The voltagewas transformed, rectified and at lastconverted to 3.3DC through a voltageregulator. Due to lack of deliveredpower from the frequency generator itwas necessary to duty cycle the load tolimit the power dissipation.The power dissipation in the voltageregulator was limited as well byswitching it on and off. When switchedoff a capacitor was charged. When in onmode the capacitor was emptied into thevoltage regulator. / Det här projektet är ämnat att hittalämpliga kretsarkitetkturer för braeffektöverföring där energikällorna ärmycket begränsade.Två kretsar ska byggas. Den första skata emot hög växelspänning motsvarandespänningen som uppkommer i ettpiezoelement vilket utsätts för växlandetryck. I det här fallet trycket från enmänniskas fotsteg. Kretsen ska leverera3.3V likspänning.Den andra kretsen ska ta emot en lågväxelspänning, vilken motsvarar spänningfrån en trådlös överföring, och leverera3.3V.Krets 1 blev aldrig testad på grund avett fallerande högspänningsaggregat.Genom att skicka en wav-fil genom en OPförstärkareskulle en simulerad spänningfrån piezoelementet användas. Därefterskulle spänningen likriktas ochkonverteras ner till 3.3V.Krets 2 testades med en signalgeneratorsom spänningskälla. Spänningentransformerades först upp innan denlikriktades och skickades in i enspänningsreglator för att därefter ge ut3.3V. Med en liten levererad effekt frånsignalgeneratorn var det nödvändigt attbegränsa effektåtgången i lasten genompulsbreddmodulering. Effektåtgången ispänningsreglatorn begränsades ocksågenom att stänga av och på IC:n(spänningsregulatorn). När IC:n varavstängd laddades en kondensator upp somsedan tömdes i IC:n då den aktiveradesigen.
2

An unknown regulator affects cell division and the timing of entry into stationary phase in Escherichia coli

Bain, Sherrie Valarie 29 August 2005 (has links)
When an essential nutrient is depleted from the medium, cultures of wildtype E. coli cells enter a period called stationary phase. The transition into stationary phase is marked by distinct changes in cell physiology, gene expression, and morphology. Pr???? and Matsumura (18) found a mutant strain of E. coli that was able to continue growing exponentially at a time when wild-type cells had stopped growing and entered stationary phase. They concluded that FlhD, a transcriptional activator of flagellar genes, was responsible for this growth phenotype and that it is a regulator of cell division (17, 18). Contrary to the findings of Pr???? and Matsumura, research in our lab has shown that the mutant growth phenotype observed in the strain used by Matsumura and Pr???? is flhD independent. This study sought to identify the second mutation, which we call cdr (cell division regulator) in the strain used by Matsumura and Pr????. We used Hfr mapping and P1 transduction to localize the mutation to a specific region of the chromosome. We also sought to determine if this growth phenotype was due to loss of function or gain of function and whether the mutation in the cdr gene was sufficient to cause the observed growth phenotype in other strain backgrounds. In addition the growth phenotype of these two strains was compared to that of other wild-type and standard laboratory E. coli strains. Our results indicate that the cdr mutation is located in the 88.5. region of the chromosome and is due to loss of Cdr function. We also discovered that the growth phenotype assigned to the mutant strain more closely reflects that of other wild-type laboratory strains as did the morphology of cells in stationary phase. This evidence suggests that the actual mutant strain might be the one that was designated as the wild-type strain by Matsumura and Pr???? and both strains may contain mutations that actually cause a decrease in cell number instead of an increase as previously reported.
3

Some studies on the endogenous gibberellings of barley (Hordeum vulgare)

Gilmour, S. J. January 1983 (has links)
No description available.
4

Development and use of a novel delivery system to investigate the chronic effects of neuropeptide Y (NPY) in vivo

Mahmoodi, Mehdi January 1999 (has links)
No description available.
5

Klimatkabinett : Komponenter och konstruktion

Ullbors, Anders January 2010 (has links)
<p>This report describes the construction of a climate-cabinet for testing of HV-cards (High Voltage) produced at VG Scienta. The main part of the report describes all the different components of the cabinet. The most important parts are a PID regulator from Eurotherm model 2408, a solid state contactor (SSC), a thermocouple, a finned resistor from DBK and different fans. The report even includes the connection between components by cable wiring, isolation, grounding, fuses and shaping of metal goods.</p><p>As the cabinet also communicates with a computer, the report includes the solution of the data communication using the software iTools from Eurotherm. The communication part includes information about a converter that converts EIA422 to USB.</p><p>The cabinet was produced at a company, called VG Scienta, in Uppsala during the spring 2010. The construction of an additional climate-cabinet was necessary because during the last year Scientas productivity increased, and it was important for the company to be able to manage the testing of an increased number of electronics.</p><p>Which solution is best for the heating of a cabinet? How does the communication work between a PC and a Eurotherm 2408 regulator? How to detect the temperature inside of the cabinet? These are some of the topics which are discussed.</p><p>The finished cabinet resembled the old cabinet in many ways. The difference between them is that the later one allows the testing of twice as many HV-cards, in an even more flexible way by the communication between the regulator and the computer. It means that the regulator parameters can be set continually and by programming it is possible to save the settings, the parameters and the curves.</p>
6

Klimatkabinett : Komponenter och konstruktion

Ullbors, Anders January 2010 (has links)
This report describes the construction of a climate-cabinet for testing of HV-cards (High Voltage) produced at VG Scienta. The main part of the report describes all the different components of the cabinet. The most important parts are a PID regulator from Eurotherm model 2408, a solid state contactor (SSC), a thermocouple, a finned resistor from DBK and different fans. The report even includes the connection between components by cable wiring, isolation, grounding, fuses and shaping of metal goods. As the cabinet also communicates with a computer, the report includes the solution of the data communication using the software iTools from Eurotherm. The communication part includes information about a converter that converts EIA422 to USB. The cabinet was produced at a company, called VG Scienta, in Uppsala during the spring 2010. The construction of an additional climate-cabinet was necessary because during the last year Scientas productivity increased, and it was important for the company to be able to manage the testing of an increased number of electronics. Which solution is best for the heating of a cabinet? How does the communication work between a PC and a Eurotherm 2408 regulator? How to detect the temperature inside of the cabinet? These are some of the topics which are discussed. The finished cabinet resembled the old cabinet in many ways. The difference between them is that the later one allows the testing of twice as many HV-cards, in an even more flexible way by the communication between the regulator and the computer. It means that the regulator parameters can be set continually and by programming it is possible to save the settings, the parameters and the curves.
7

Control and implementation of integrated voltage regulators

Fletcher, Jay Brady 25 February 2014 (has links)
This dissertation describes the development of voltage regulators for the purpose of power reduction and further scaling in highly integrated system-on-chip products. Emphasis is placed on the architecture and implementation of integrated voltage regulation using commercially available components, standard CMOS technology, and a practical controller. The research spans the fundamental elements, architectural aspects, and detailed analog integrated circuit design. / text
8

Novel Full Bridge Topologies for VRM Applications

Ye, Sheng 28 February 2008 (has links)
Multi-phase Buck is widely used in Voltage Regulator Modules design because of its low cost and simplicity. But this topology also has a lot of drawbacks. One of the most fundamental drawback is that it has narrow duty cycles when it operates at high switching frequency with low output voltage (for example 1V). Narrow duty cycles yield high switching loss which limits the switching frequency of Buck; making it difficult to design a Buck based VRM that can achieve high efficiency at a high switching frequency. In this thesis three new non-isolated full bridge topologies will be introduced to solve the aforementioned problems of Buck. One is a new non-isolated full bridge topology, this new topology use a transformer to extend the duty cycle and it capable to achieve zero voltage switching. Experimental results demonstrate that it has significant advantages over multi-phase Buck. In some applications when huge output current is required, several converters are paralleled to supply the current that is not an optimal solution. Two two-phase non-isolated full bridge topologies are proposed to solve this problem. They double the output power of one-phase non-isolated full bridge, and achieve higher efficiency with fewer switches compared with parallel two non-isolated full bridge converters. Non-isolated VRM usually is used for personal computers, VRM for servers is called power pod, and usually isolation is required for power pod due to safety considerations. Server usually require much more power than personal computers, their power consumption is around several KW. To provide the power for the server a few power modules will need to be paralleled, this kind solution is expensive and make current sharing complex. In this thesis two new two-phase isolated full bridge topologies are proposed. They are capable to operate at soft switching mode. And they double the output power compared with conventional full bridge converter. Compared with parallel two full bridge converters, they can achieve higher efficiency with fewer switches. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2008-02-28 09:53:50.23
9

Development and Evaluation of a Fluorescent Activated Droplet Sorting Regulatory Assay for Ribosomal Cis-Regulatory RNAs:

Gray, Elizabeth Catherine January 2022 (has links)
Thesis advisor: Michelle M. Meyer / Existing methods of assaying the function of cis-regulatory RNAs come with significant drawbacks when assaying large RNA libraries. Highly sensitive cell-based assays such as the β galactosidase assay are labor intensive, difficult to scale up and may lose sensitivity with increased throughput. GFP and luciferase reporters can be used with FACS to increase assay throughput, but sorting small bacterial cells is challenging and greatly reduces assay sensitivity. Conversely, in vitro methods allow for fast screening of very large RNA libraries, but only select for properties of binding, not regulation. By combining the principles of classic in cell regulatory assays with modern tools, cis-regulatory RNAs can be quickly screened for regulatory activity at a large scale. The assay under development, Fluorescent Activated Droplet Sorting Regulatory Assay (FADSRA), uses microfluidics to encapsulate single cells expressing a fluorescent protein under the control of a cis-regulatory RNA. These cells are then cultured into microcolonies within the droplets, which are subsequently sorted according to fluorescent signal. Deep amplicon sequencing of the regulatory RNAs can then reveal which sequences can regulate and which cannot. Thus, FADSRA can help bridge the gap between in vitro RNA binding and gene regulation assays, providing a way to answer sophisticated questions about cis-regulatory RNAs requiring high-throughput assay methods. While many applications for FADSRA are possible, such as verifying regulatory activity of in vitro binders or screening synthetic regulators, one such application of FASDRA is the creation of fitness landscapes that probe sequence-function relationships of RNA cis-regulators. This dissertation first develops and optimizes the regulatory assay for ribosomal leaders in Chapter 2, following by creating a single mutant fitness landscape of the E. coli S15 leader RNA in Chapter 3. Results of this fitness landscape largely support previously published mutational studies and highlight the necessity of stable hairpin formation for regulation of the E. coli S15 leader. Chapter 4, examining the regulation of S15 protein and leader homologs, and Chapter 5, testing the adaptability of FADSRA to other cis-regulatory RNAs, examine possible further applications of the assay. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Biology.
10

Návrh interního napěťového regulátoru pro automobilové aplikace / Design of an internal voltage regulator for automotive applications

Bryndza, Ivan January 2017 (has links)
This work contains topology and circuit design of a linear voltage regulator with respect to suppression of disturbances coming from supplied circuit into the input of the regulator. The converter is designed for integration in automotive sensor applications.

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