177 research outputs found
Design of a Twelve Bit, Four Hundred Mega-Samples-per-Second, Interpolating Dual Channel Digital to Analog Converter Featuring Digital Modulation
No full textabstract: Digital to analog converters (DACs) find widespread use in communications equipment. Most commercially available DAC's which are intended to be used in transmitter applications come in a dual configuration for carrying the in phase (I) and quadrature (Q) data and feature on chip digital mixing. Digital mixing offers many benefits concerning I and Q matching but has one major drawback; the update rate of the DAC must be higher than the intermediate frequency (IF) which is most commonly a factor of 4. This drawback motivates the need for interpolation so that a low update rate can be used for components preceding the DACs. In this thesis the design of an interpolating DAC integrated circuit (IC) to be used in a transmitter application for generating a 100MHz IF is presented. Many of the transistor level implementations are provided. The tradeoffs in the design are analyzed and various options are discussed. This thesis provides a basic foundation for designing an IC of this nature and will give the reader insight into potential areas of further research. At the time of this writing the chip is in fabrication therefore this document does not contain test results.Dissertation/ThesisM.S. Electrical Engineering 201
Class D Audio Amplifier Design with Power Supply Noise Cancellation
No full textabstract: In this thesis, a digital input class D audio amplifier system which has the ability
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.Dissertation/ThesisMasters Thesis Electrical Engineering 201
Exit Temperature Profile Measurement and CFD Comparisons on Small Scale Turbojet Combustor with Air Blast Atomizer Configuration
No full textPreliminary investigation of a swirl stabilized premixed combustor
No full textExperiments were conducted in a swirl stabilized premixed combustor at atmospheric pressure in order to study the stability and structure of lean premixed methane air flames. Swirl number of the combustor was 0.74. The lab scale combustor was operated up to 30 kW of thermal power during measurements. Experiments focused on two main aspects of the combustion system. First the relation between the cold flowfield and the flame stabilization is examined. It is observed that, the structure of the flame near the dump plane corresponds closely to the features of the non-reacting air flowfield. The flame is seen to be stabilized on the boundary of the recirculation region. Lean blowout limits of the combustor that operates within the flamelet regime were also recovered. A correlation linking the blowout equivalence ratio to laminar flame speed is presented. (C) 2012 Elsevier Ltd. All rights reserved
Affirmative Action in India: Restricted Strategy Space, Complex Constraints, and Direct Mechanism Design
No full textSince the 1950s, India has instituted an intricate affirmative action program
through a meticulously designed reservation system. This system incorporates
vertical and horizontal reservations to address historically marginalized groups’ socioeconomic imbalances. Vertical reservations designate specific quotas of available
positions for Scheduled Castes, Scheduled Tribes, Other Backward Classes, and
Economically Weaker Sections. Concurrently, horizontal reservations are employed
within each vertical category to allocate positions for additional subgroups, such as
women and individuals with disabilities. In educational admissions, the legal framework
recommended that unfilled positions reserved for the OBC category revert to
unreserved status. Moreover, we document that individuals from vertically reserved
categories have more complicated preferences over institution-vertical category position
pairs, even though authorities only elicit their preferences over institutions. To
address these challenges, the present paper proposes a novel class of Generalized
Lexicographic (GL) choice rules. This class is comprehensive, subsuming the most
salient priority structures discussed in the extant matching literature. Utilizing the GL
choice rules and the deferred acceptance mechanism, we present a robust framework
that generates equitable and effective solutions for resource allocation problems in the
Indian context.JEL Classification: C78, D02, D47, I38Length: 41 pages Original Release Date: October 4, 2023Revision: November 1, 2023Latest Revision: November 22, 2023 Copyright 2023, The Author
An Electrical Stimulus based Built In Self Test (BIST) circuit for Capacitive MEMS accelerometer
No full textabstract: Micro Electro Mechanical Systems (MEMS) is one of the fastest growing field in silicon industry. Low cost production is key for any company to improve their market share. MEMS testing is challenging since input to test a MEMS device require physical stimulus like acceleration, pressure etc. Also, MEMS device vary with process and requires calibration to make them reliable. This increases test cost and testing time. This challenge can be overcome by combining electrical stimulus based testing along with statistical analysis on MEMS response for electrical stimulus and also limited physical stimulus response data. This thesis proposes electrical stimulus based built in self test(BIST) which can be used to get MEMS data and later this data can be used for statistical analysis. A capacitive MEMS accelerometer is considered to test this BIST approach. This BIST circuit overhead is less and utilizes most of the standard readout circuit. This thesis discusses accelerometer response for electrical stimulus and BIST architecture. As a part of this BIST circuit, a second order sigma delta modulator has been designed. This modulator has a sampling frequency of 1MHz and bandwidth of 6KHz. SNDR of 60dB is achieved with 1Vpp differential input signal and 3.3V supplyDissertation/ThesisM.S. Electrical Engineering 201
Improvement of the Strength of Ankara Clay with Self-cementing High Alkaline Fly Ash
No full textAbstractTurkey's plants are fired by lignite, producing class C fly ash containing a high percentage of lime. Sulphate and alkali levels are also higher in class C fly ashes. Therefore, fly ash is, commonly, unsuitable as an additive in cement or concrete in Turkey. In this study, highly alkaline fly ash obtained from the Yenikoy thermal power plants is combined with soil samples in different proportions (5%, 15%, and 25%) and changes in the geomechanical properties of Ankara clay were investigated. The effect of curing time on the physical-mechanical properties of the fly ash mixed soil samples was also analyzed. Free swelling index values showed a decrease of 92.6%. The California bearing ratio has seen a more drastic increase in value (68.7 times for 25% fly ash mix)
Some health indicators in Etimesgut health training and research area (Ankara, Turkey, 1967-1988) Etimesgut saglik egitim ve arastirma bolgesinde bazi saglik olcutlerinin degerlendirilmesi (1967-1988).
No full textThe author examines health indicators such as neonatal and maternal morbidity and mortality for the period 1967-1988 at the Etimesgut health training and research area, Turkey. The purpose of the study is to evaluate health care services. (SUMMARY IN ENG
Replication-Independent Histone Variant H3.3 Controls Animal Lifespan through the Regulation of Pro-longevity Transcriptional Programs
No full textSummaryChromatin structure orchestrates the accessibility to the genetic material. Replication-independent histone variants control transcriptional plasticity in postmitotic cells. The life-long accumulation of these histones has been described, yet the implications on organismal aging remain elusive. Here, we study the importance of the histone variant H3.3 in Caenorhabditis elegans longevity pathways. We show that H3.3-deficient nematodes have negligible lifespan differences compared to wild-type animals. However, H3.3 is essential for the lifespan extension of C. elegans mutants in which pronounced transcriptional changes control longevity programs. Notably, H3.3 loss critically affects the expression of a very large number of genes in long-lived nematodes, resulting in transcriptional profiles similar to wild-type animals. We conclude that H3.3 positively contributes to diverse lifespan-extending signaling pathways, with potential implications on age-related processes in multicellular organisms
Egitura, prozesu eta nortasun soziala ekoizpen kulturaletan, Zuberoako Folk-antzerkiaren adibide baten harira
No full textThis essay fouses on folk cultural performance in a Pyrenean Basque-speaking land called Zuberoa. Its author analyses sereval issues: the need of a diacronic look into cultural performance; politics of folk performance; the groundsfor conflict and legitimacy among organisers; and making of autoritative statements in the public definition of cultural performance.Saio honek Zuberoako folk-antzerkiaz dihardu, Pastorala deritzan antzezkizuna antolatzeak dakartzan gora-behera soziokulturalak miatuz. Bertan zenbait analisi-esparru daude, haietako batzuk hauek direlarik: antropologia sinkronikoen eta diakronikoen arteko aldeak; folk-antzerkia eta bertako politika-erak eta politikakerak; folk-antzerkiaren audientzia eta aktorego bereziaren beharra; folk-antzerkiak inguratzen duen harreman-sarearen barruan gatazkak sortzen dituen gaiak; eta errealitatearen definiziogune agintariak
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