Browsing by Subject "power"
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Item Analysis and Design of Smart PV Module(2012-12-10) Mazumdar, PoornimaThis thesis explores the design of a smart photovoltaic (PV) module- a PV module in which PV cells in close proximity are electrically grouped to form a pixel and are connected to dc-dc converter blocks which reside embedded in the back pane of the module. An auto-connected flyback converter topology processing less than full power is used to provide high gain and perform maximum power point tracking (MPPT). These dc-dc converters interface with cascaded H-bridge inverter modules operating on feed forward control for dc-link voltage ripple rejection. By means of feed forward control, a significant reduction in dc link capacitance is achieved by enduring higher dc link ripple voltages. The dc link electrolytic capacitors are replaced with film capacitors thus offering an improvement in the reliability of the smart PV module. The proposed configuration is capable of producing 120V/ 240V AC voltage. The PV module now becomes a smart AC module by virtue of embedded intelligence to selectively actuate the individual dc-dc converters and control the output AC voltages directly, thus becoming a true plug and power energy system. Such a concept is ideal for curved surfaces such as building integrated PV (BIPV) system applications where gradients of insolation and temperature cause not only variations from PV module-to-PV module but from group-to-group of cells within the module itself. A detailed analysis along with simulation and experimental results confirm the feasibility of the proposed system.Item Development of Models for Series and Parallel Fan Variable Air Volume Terminal Units(Texas A&M University, 2007-09-17) Furr, James C., JrEmpirical models of airflow output and power consumption were developed for series and parallel fan powered variable air volume terminal units at typical design pressure conditions. A testing procedure and experimental setup were developed to test sets of terminal units from three different manufacturers. Each set consisted of two series and two parallel units, each with 8 in. (203 mm) and 12 in. (304 mm) primary air inlets, for a total of four units in each set. Generalized models were developed for the series and parallel units, with coefficients varying by size and manufacturer. Statistical modeling utilized SAS software (2002). Fan power and airflow data were collected at downstream static pressures over a range from 0.1 to 0.5 in. w.g. (25 to 125 Pa) for the parallel terminal units. Downstream static pressure was held constant at 0.25 in. w.g. (62 Pa) for the series units. Upstream static pressures of all variable air volume (VAV) terminal units ranged from 0.1 to 2.0 in. w.g. (25 to 498 Pa). Data were collected at four different primary air damper positions. Data were also collected at four different terminal unit fan speeds, controlled by a silicon controlled rectifier (SCR). The models utilized the RMS voltage entering the terminal unit fan, the 'rake' sensor velocity pressure, and the downstream static pressure. In addition to the terminal unit airflow and power models, a model was developed to quantify air leakage in parallel terminal units, when the unit fan was off. In all but two of the VAV terminal units, the resulting models of airflow and power had R2 values greater than 0.90. In the two exceptions, there appeared to be manufacturing defects: either excessive air leakage or a faulty SCR that limited the effectiveness of the airflow and power models to capture the variation in the data.Item Domestic Surveillance and Government's Loss of Legitimacy(2014-06-09) Inks, Christopher Scott; Inks, Christopher Scott; Phelps, James R; Phelps, James RThe terrorist attacks against the United States on the morning of September 11, 2001 created an environment ripe for the abuse of power. With a fearful nation clamoring for greater protection against future attacks, the National Security Administration (NSA) took the opportunity to create and implement a secret domestic spying and data mining program, the size of which had never before been imagined. Because information is the ultimate form of power in today’s world, unmitigated access to so much personal data has the potential to aggregate power into this one agency, leaving the rest of government and the populace unable to defend themselves against those who would use it to advance their own agendas. Once obtained, there is no way to check this power. Since government is only as legitimate as the populace believes it to be, such aggregations of power are likely to increase dissent among the citizenry and ultimately result in a belief that it has become illegitimate. Such a government is ineffective and puts the entirety of the populace in harm’s way, not only from terrorists outside its borders, but from potential domestic abuses of this power. In the rush to protect the country against terrorism, one must be careful the actions he or she takes do not inadvertently create a homeland security threat from within.Item Intra-Set Rest Intervals in Hypertrophic Training: Effects on Hypertrophy, Strength, Power, and Myosin Heavy Chain Composition(2012-10-19) Oliver, JonathanThe purpose of this study was to compare the effects of intra-set rest intervals (ALT) and traditional resistance (STD) training in hypertrophic resistance training. 22 males (25 +/- 5yrs, 179.71 +/- 5.0cm, 82.1 +/- 10.6kg, 13.6 +/- 4.3% fat, 6.5 +/- 4.5yrs training) were matched according to baseline characteristics and randomly assigned to a STD or ALT 12 week hypertrophic training protocol. Body composition, strength (1RM bench and squat); power (60% 1RM bench and squat); and vertical jump were assessed at baseline, 4, 8, and 12 weeks. Muscle biopsy for myosin heavy chain (MHC) was performed pre and post training. A 2 x 4 (Group x Time) ANOVA was used to assess changes in body composition. A 2 x 4 (Group x Time) ANCOVA covaried by baseline performance measures was used to assess differences in strength and power characteristics. A 2 x 2 (Group x Time) ANCOVA covaried for baseline percentage MHC was used to determine differences pre and post training. Both groups experienced increases in FFM with no differences between groups (62.6 +/- 7.9, 63.4 +/- 7.6, 64.2 +/- 7.4, 64.2 +/- 7.5kg; p>0.05). No time effects were noted in percent fat (13.6 +/- 4.3, 14.1 +/- 4.7, 14.0 +/- 4.6, 14.3 +/- 4.6%fat; p>0.05). Increase in FFM was associated with a decrease in MHCIIX, (ALT, -37.9 +/- 24.1%; STD, -23.4 +/- 23.8%; p = 0.001) and an increase in MHCIIA (ALT, 32.0 +/- 28.8%; STD, 25.4 +/- 29.1%; p = 0.001) with no difference between groups. A significant interaction was observed with the ALT group experiencing greater gains in both 1RM bench (STD 104.1 +/- 27.6, 102.7 +/- 29.0, 107.0 +/- 25.3, 113.2 +/- 27.3; ALT 110.9 +/- 20.1, 117.5 +/- 23.7, 120.8 +/- 22.6, 126 +/- 22.8; p<0.05) and 1RM squat (STD 123.3 +/- 39.3, 139.6 +/- 38.8, 160.2 +/- 36.1, 171.8 +/- 34.5; ALT 130.1 +/- 25.1, 152.6 +/- 24.8, 179.8 +/- 24.5, 193.9 +/- 24.2kg; p<0.05). The ALT group experienced greater gains in power in both the bench (STD 560 +/- 122, 541 +/- 105, 572 +/- 122, 593 +/- 135W; ALT 575 +/- 102, 586 +/- 123, 646 +/- 103, 658 +/- 113W; p<0.05) and vertical jump (STD 1378 +/- 237, 1418 +/- 214, 1452 +/- 210, 1470 +/- 215W; ALT 1389 +/- 179, 1434 +/- 152, 1470 +/- 149, 1537 +/- 150W;p<0.05), with gains in squat power approaching significance (STD 625 +/- 245, 704 +/- 233, 723 +/- 227, 830 +/- 232W; ALT 632 +/- 171, 734 +/- 179, 783 +/- 188, 914 +/- 207W; p<0.10). The use of intra-set rest intervals in programs designed to elicit hypertrophy results in greater gains in strength and power with no significant difference in lean mass or MHC composition after a 12 week resistance training program designed to elicit hypertrophy.Item Language and power in Roman comedy(2009-05) Rich, Laura Brooke; Moore, Timothy J., 1959-; Riggsby, Andrew M.The theory of powerless speech suggests that speakers in powerless social positions use more “powerless” speech acts than their social superiors. This report will use two such powerless speech acts, hedges and tag questions, to examine the interplay between the power relationships of Roman comedy and the language of its characters. The results of this study show that Republican Latin does not always follow the theory’s predictions, suggesting that hedges and tag questions may not be powerless speech acts in Latin; that the theory may need to be modified in order to accommodate Latin; or that the Saturnalian nature of Roman comedy prevents the expected outcome of powerless language.Item Minimizing and exploiting leakage in VLSI(2009-05-15) Jayakumar, NikhilPower consumption of VLSI (Very Large Scale Integrated) circuits has been growing at an alarmingly rapid rate. This increase in power consumption, coupled with the increasing demand for portable/hand-held electronics, has made power consumption a dominant concern in the design of VLSI circuits today. Traditionally dynamic (switching) power has dominated the total power consumption of VLSI circuits. However, due to process scaling trends, leakage power has now become a major component of the total power consumption in VLSI circuits. This dissertation explores techniques to reduce leakage, as well as techniques to exploit leakage currents through the use of sub-threshold circuits. This dissertation consists of two studies. In the first study, techniques to reduce leakage are presented. These include a low leakage ASIC design methodology that uses high VT sleep transistors selectively, a methodology that combines input vector control and circuit modification, and a scheme to find the optimum reverse body bias voltage to minimize leakage. As the minimum feature size of VLSI fabrication processes continues to shrink with each successive process generation (along with the value of supply voltage and therefore the threshold voltage of the devices), leakage currents increase exponentially. Leakage currents are hence seen as a necessary evil in traditional VLSI design methodologies. We present an approach to turn this problem into an opportunity. In the second study in this dissertation, we attempt to exploit leakage currents to perform computation. We use sub-threshold digital circuits and come up with ways to get around some of the pitfalls associated with sub-threshold circuit design. These include a technique that uses body biasing adaptively to compensate for Process, Voltage and Temperature (PVT) variations, a design approach that uses asynchronous micro-pipelined Network of Programmable Logic Arrays (NPLAs) to help improve the throughput of sub-threshold designs, and a method to find the optimum supply voltage that minimizes energy consumption in a circuit.Item Modeling and design of compact microwave components and systems for wireless communications and power transmission(Texas A&M University, 2004-09-30) Zepeda, PaolaThe contribution of the work here presented involves three main topics: Wireless Power Transmission (WPT) technology, phased array systems, and microwave components design and modeling. The first topic presents the conceptual design of a WPT system at 2.45GHz with 90% efficiency and 1MW of DC output power. Second, a comparative study between 2.45 and 35GHz WPT operation is provided. Finally, the optimization of a taper distribution with reduced thermal constraints on a sandwich transmitter is realized. For a 250- and 375-m antenna radius, 89.7% of collection efficiency with 29% reduction in maximum power density (compared to the Gaussian), and 93% collection efficiency with 39% reduction of maximum power density, are obtained respectively with two split tapers. The reduction in maximum power density and the use of split taper are important to alleviate the thermal problems in high power transmission. For the phased array project, the conceptual design of a small-scale system and in-depth analysis using two main approaches (statistical and field analysis) is realized. Practical aspects are addressed to determine the phased array main design features. The statistical method provides less accurate results than the field analysis since it is intended for large arrays. Careful theoretical analysis led to good correlation between statistical, field analysis and experimental results. In the components chapter, efficient loop transitions used in a patch antenna array are designed at K- and W-band. Measured insertion loss (IL) K-band loop is under 0.4dB. The K- and W-band antenna array measured broadside gains are 23.6dB at 24.125GHz and 25dB at 76.5GHz with return loss under 9.54dB from 24 to 24.4GHz and 12 dB from 75.1 to 77.3GHz, respectively. Also, a multilayer folded line filter is designed at 5.8GHz and compared to planar ring filters. Improved measured bandwidth from 2GHz to 7.5GHz and IL of 1.2dB are obtained with approximately half the size of a planar ring resonator. Thirdly, a simplified switch model is implemented for use in broadband phased-shifters. The model presents very good fit to the measured results with an overall total error under 3%, magnitude error less than 8%, and phase errors less than ?0.4?.Item Status & solidarity through codeswitching: three plays by Dolores Prida(Texas A&M University, 2004-09-30) Anderson, Sheri L.This analysis employs the sociolinguistic framework of status and solidarity (Holmes, 2001) to examine the use of codeswitching on the relational development between the characters in three plays by Cuban-American playwright Dolores Prida. The three plays discussed are Beautiful Se?oritas (1978), Coser y cantar (1981) and Bot?nica (1991). Linguistic scholars recognize the lack of linguistic analysis of literary texts; specifically, codeswitching at present is not fully explored as a linguistic phenomenon in written contexts. Furthermore, Prida's works have never before been appraised using linguistic methodology. Hence, this work aims to add to scholarly research in the fields of codeswitching, discourse analysis, and literary linguistics, using the status and solidarity framework to examine the codeswitching in Dolores Prida's plays. Dolores Prida is a feminist and Hispanic dramatist whose central theme is the search for identity of Hispanic immigrants, specifically women, in the United States today. Due to her ideological stance, it is expected that a strong emphasis on solidarity rather than status and the use of affective rather than referential speech functions are present in the relationships in her plays. Accordingly, the analysis of Bot?nica reveals that indeed codeswitching between the characters does affect their relational development in maintaining solidarity and intimacy. However, the relationships found in Beautiful Se?oritas and Coser y cantar do not offer such conclusions, due to the variable nature of the relationships identified. Further analysis of these and other literary works will more accurately determine benefits of the status and solidarity framework as applied to the codeswitching research.Item The Effects of Relative Power on Role-Taking Accuracy(2012-10-19) Love, TonyI conduct an experiment to test the impact of relative power differential on the relationship between gender and role-taking accuracy. First in an 80 subject study, and then in the current study, role-taking accuracy is conceptualized as the accuracy with which one can predict the behavior of another or others. In Study 1, I examined self-evaluative measures of role-taking ability and found that self-evaluative measures of role-taking do not correlate with actual role-taking accuracy. In addition, women were more accurate role-takers than were men in same-gender dyads regardless of the existence of a prior relationship between the two individuals. This prior experimental research showed that female friends were much more accurate role-takers than were male friends. In fact, female strangers were more accurate role-takers than were male friends. It is my conjecture however, that role taking ability is not directly connected to gender; rather I propose that it is a situationally prompted ability based on the need for individuals of relatively less power to predict the behavior of individuals with relatively more power. In other words, while women are, indeed, better role takers, this is not a general ability; rather it is prompted by their relatively low positions of power. In Study 2, I examine role-taking accuracy under conditions in which differential power is assigned to one member of a dyad and established through interaction. I predict that power position will account for variability in role-taking accuracy, but gender will not. I tested this hypothesis using power balanced and power-imbalanced, task-oriented, same and cross gender dyads. I found that power position does account for variation in role-taking accuracy while gender and gender composition of the dyad do not account for variation in role-taking accuracy.Item To enter and lead: renegotiating meanings of leadership and examining leadership theory of social power from the perspectives of African American women leaders in predominantly white organizations(2009-05-15) Byrd, Marilyn YvonneThis qualitative, phenomenological study examined the leadership experiences of 10 African American women (AAW)--current or former leaders in predominantly white organizations--to gain an understanding of how well, or not, AAW?s leadership is represented by traditional and dominant leadership theory. The purpose of this study was to bring the interlocking system of race, gender, and social class (intersectionality) to the conversation on leadership by adding the perspectives of AAW and challenging the traditional and dominant assumptions about the phenomenon of leadership. The data were collected using in-depth interviews and analyzed using a form of narrative analysis. This study confirmed findings from prior research that AAW in positions of leadership: 1) often encounter disempowering experiences whereby their authority is questioned or challenged, 2) experience exclusion from the good ole boy social networks, 3) experience being an outsider-within--feelings of alienation as the only African American person in group settings, 4) express needing to have their qualifications validated before being accepted in their roles, and 5) are challenged to de-myth the stereotypical images that society has sanctioned upon AAW. The most salient encounters the women in this study had were disempowering experiences whereby their race, gender, and/or social class were perceived as creating a challenge to their positions of leadership. Based on the experiences of the participants in this study, traditional and dominant leadership theories, such as French and Raven's (1959) theory of social power that have generally represented the perspectives of white, middle class men, are inadequate for explaining the experiences of AAW. On the other hand socio-cultural theories such as black feminist thought and critical race theory (CRT) offer a wealth of knowledge for explaining how social systems such as race, gender, and social class can be used to maintain a status of marginalization. This study contributes to the fields of HRD and Higher Education (HE). First, leadership development programs should emphasize the socio-cultural challenges to leadership. Second, researchers should broaden the theories that inform the study of leadership. Finally, both fields should begin introducing and utilizing culturally inclusive terms, such as intersectionality, that are not generally associated with the study of leadership.Item Variation and power issues in VLSI clock networks(2009-05-15) Venkataraman, GaneshClock Distribution Network (CDN) is an important component of any synchronous logic circuit. The function of CDN is to deliver the clock signal to the clock sinks. Clock skew is defined as the difference in the arrival time of the clock signal at the clock sinks. Higher uncertainty in skew (due to PVT variations) degrades circuit performance by decreasing the maximum possible delay between any two sequential elements. Aggressive frequency scaling has also led to high power consumption especially in CDN. This dissertation addresses variation and power issues in the design of current and potential future CDN. The research detailed in this work presents algorithmic techniques for the following problems: (1) Variation tolerance in useful skew design, (2) Link insertion for buffered clock nets, (3) Methodology and algorithms for rotary clocking and (4) Clock mesh optimization for skew-power trade off. For clock trees this dissertation presents techniques to integrate the different aspects of clock tree synthesis (skew scheduling, abstract topology and layout embedding) into one framework- tolerance to variations. This research addresses the issues involved in inserting cross-links in a buffered clock tree and proposes design criteria to avoid the risk of short-circuit current. Rotary clocking is a promising new clocking scheme that consists of unterminated rings formed by differential transmission lines. Rotary clocking achieves reduction in power dissipation clock skew. This dissertation addresses the issues in adopting current CAD methodology to rotary clocks. Alternative methodology and corresponding algorithmic techniques are detailed. Clock mesh is a popular form of CDN used in high performance systems. The problem of simultaneous sizing and placement of mesh buffers in a clock mesh is addressed. The algorithms presented remove the edges from the clock mesh to trade off skew tolerance for low power. For clock trees as well as link insertion, our experiments indicate significant reduction in clock skew due to variations. For clock mesh, experimental results indicate 18.5% reduction in power with 1.3% delay penalty on a average. In summary, this dissertation details methodologies/algorithms that address two critical issues- variation and power dissipation in current and potential future CDN.