Steady State Voltage Stability Enhancement Using Shunt and Series FACTS Devices

It is specifically important to focus on voltage stability analysis of the power system to avoid worst case scenarios such as voltage collapse. The purpose of this thesis is to identify methods for enhancing the steady-state voltage stability using FACTS devices and determining their impact on real and reactive power losses, improvement of bus voltage magnitude, and transmission line loadability. To achieve this, FACTS devices such as Static VAR Compensator (SVC), Static Synchronous Compensator (STATCOM), and Thyristor Controlled Series Capacitor (TCSC) are used in the test system as three separate test cases. The results obtained assist in drawing conclusions on the effectiveness of each FACTS devices at generator, load and swing buses, on lines between two load buses, and between a load bus and a generator bus, in terms of metrics such as voltage magnitude profile, PV curves, and active and reactive power losses

A Medical Data Cleaner

This report describes medical-data cleaning tool, called MedDataCleaner that can detect outliers in medical data and assistant Database Administrators in resolving data-related problem. Specifically, MedDataCleaner, enables the users to define cleaning rules and offers the ability to choose classification methods that help determine if the data is good or bad. MedDataClearer uses Vitruvian DB objects for object-relation mapping (ORM) support and Vitruvian alignment links for designing the GUI. My contribution towards this work includes designing the user interfaces using Vitruvian Alignment links, design and implement mean, standard deviation and neural classification methods using Vitruvian DB objects

CMOS Signal Synthesizers for Emerging RF-to-Optical Applications

The need for clean and powerful signal generation is ubiquitous, with applications spanning the spectrum from RF to mm-Wave, to into and beyond the terahertz-gap. RF applications including mobile telephony and microprocessors have effectively harnessed mixed-signal integration in CMOS to realize robust on-chip signal sources calibrated against adverse ambient conditions. Combined with low cost and high yield, the CMOS component of hand-held devices costs a few cents per part per million parts. This low cost, and integrated digital processing, make CMOS an attractive option for applications like high-resolution imaging and ranging, and the emerging 5-G communication space. RADAR techniques when expanded to optical frequencies can enable micrometers of resolution for 3D imaging. These applications, however, impose upto 100x more exacting specifications on power and spectral purity at much higher frequencies than conventional RF synthesizers. This generation of applications will present unconventional challenges for transistor technologies - whether it is to squeeze performance in the conventionally used spectrum, already wrung dry, or signal generation and system design in the relatively emptier mm-Wave to sub-mmWave spectrum, much of the latter falling in the ``Terahertz Gap". Indeed, transistor scaling and innovative device physics leading to new transistor topologies have yielded higher cut-off frequencies in CMOS, though still lagging well behind SiGe and III-V semiconductors. To avoid multimodule solutions with functionality partitioned across different technologies, CMOS must be pushed out of its comfort zone, and technology scaling has to have accompanying breakthroughs in design approaches not only at the system but also at the block level. In this thesis, while not targeting a specific application, we seek to formulate the obstacles in synthesizing high frequency, high power and low noise signals in CMOS and construct a coherent design methodology to address them. Based on this, three novel prototypes to overcome the limiting factors in each case are presented. The first half of this thesis deals with high frequency signal synthesis and power generation in CMOS. Outside the range of frequencies where the transistor has gain, frequency generation necessitates harmonic extraction either as harmonic oscillators or as frequency multipliers. We augment the traditional maximum oscillation frequency metric (fmax), which only accounts for transistor losses, with passive component loss to derive an effective fmax metric. We then present a methodology for building oscillators at this fmax, the Maximum Gain Ring Oscillator. Next, we explore generating large signals beyond fmax through harmonic extraction in multipliers. Applying concepts of waveform shaping, we demonstrate a Power Mixer that engineers transistor nonlinearity by manipulating the amplitudes and relative phase shifts of different device nodes to maximize performance at a specific harmonic beyond device cut-off. The second half proposes a new architecture for an ultra-low noise phase-locked loop (PLL), the Reference-Sampling PLL. In conventional PLLs, a noisy buffer converts the slow, low-noise sine-wave reference signal to a jittery square-wave clock against which the phase of a noisy voltage-controlled oscillator (VCO) is corrected. We eliminate this reference buffer, and measure phase error by sampling the reference sine-wave with the 50x faster VCO waveform already available on chip, and selecting the relevant sample with voltage proportional to phase error. By avoiding the N-squared multiplication of the high-power reference buffer noise, and directly using voltage-mode phase error to control the VCO, we eliminate several noisy components in the controlling loop for ultra-low integrated jitter for a given power consumption. Further, isolation of the VCO tank from any varying load, unlike other contemporary divider-less PLL architectures, results in an architecture with record performance in the low-noise and low-spur space. We conclude with work that brings together concepts developed for clean, high-power signal generation towards a hybrid CMOS-Optical approach to Frequency-Modulated Continuous-Wave (FMCW) Light-Detection-And-Ranging (LIDAR). Cost-effective tunable lasers are temperature-sensitive and have nonlinear tuning profiles, rendering precise frequency modulations or 'chirps' untenable. Locking them to an electronic reference through an electro-optic PLL, and electronically calibrating the control signal for nonlinearity and ambient sensitivity, can make such chirps possible. Approaches that build on the body of advances in electrical PLLs to control the performance, and ease the specification on the design of optical systems are proposed. Eventually, we seek to leverage the twin advantages of silicon-intensive integration and low-cost high-yield towards developing a single-chip solution that uses on-chip signal processing and phased arrays to generate precise and robust chirps for an electronically-steerable fine LIDAR beam

Sexual Health Misinformation and Potential Interventions Among Youth on Social Media

With the rise of the internet and social media, many adolescents and young adults have turned to the internet and social media for sexual health information. However, this can be problematic because sexual health misinformation on social media utilizes a variety of techniques to quickly disseminate and retain that misinformation in users. Historically, the spread of sexual health misinformation has specifically negatively impacted adolescents and young adults regarding two sexual health topics: contraceptives and HPV vaccination. Current evidence demonstrates that a combination of corrections and inoculation would be effective against general health misinformation. However, there is a lack of research on interventions aimed specifically at sexual health misinformation among adolescents and young adults. It is imperative that researchers further investigate interventions against sexual health misinformation among adolescents and young adults since confounding factors may influence the efficacy of currently studied methods

How to write about China and India

The first BJHS Themes, a new, fully open access, peer-reviewed journal from the British Society for the History of Science, was published this month. The issue is entitled Science of Giants: China and India in the twentieth century. In this article, one of the volume’s editors, Jahnavi Phalkey, gives her observations on the opportunities and challenges on writing about China and India

Stigma and Reputation: Exploring the Lingering Effects of Organizational Stigma

Stigmas have been widely used to describe organizations and individuals that have negative reputations or that have engaged in illegitimate practices. Extensive research has been done on the effects of positive reputation and personal reputation. However, there is still much to learn about the effects and consequences of organizational stigmas. The purpose of this paper is to provide a theoretical overview of the consequences of organizational stigmas, particularly in the area of employee mobility, and to help understand the relationship between negative organizational reputation and personal reputation. Contributions of this research, the limitations and directions for future research are discussed as well

Re-visioning the ethics of care: femininity, cosmopolitanism and contemporary women’s writings

Abstract: Carol Gilligan proposed the concept of an ‘ethics of care’ in her book, In a Different Voice: Psychological Theory and Women’s Development, published in 1982. Her argument was written in agonistic response to a revival of neo-Kantian ethical theorising in the seventies philosophical arguments that granted women a distinctly subordinate place to men as fully fledged ethical beings. In opposition to these theories-- particularly those of Lawrence Kohlberg-- which considered women to be too involved in personal relationships to be able to achieve the requisite levels of detachment to morally gauge ethically demanding situations, Gilligan argued for an ethical code that privileges relationships of involvement and care over abstract principles of a categorical imperative type. She argued that women who felt the need to prioritise such relationships are not deficient in their ethical sensibility but function according to a different but most certainly fully viable value system. Gilligan’s thesis came under fire from later feminists and ethical theorists as the concept of difference took a new turn in feminist theory-- especially post-structuralist-inflected theory of the later eighties and nineties. It is my contention in this thesis that her ideas are still crucially important. And as ethical theory comes to recognise the important role of affect in moral and ethical judgement, her ideas can be revisited in relation to contemporary preoccupation with these issues about knowing and judging. Although revolutionary in its proposition that different people may have different ways of responding to ethically significant situations, Gilligan’s theory of care does not question the traditionally imposed binary between man and women as being rational and emotional respectively. My argument, substantiated by my analysis of current fiction by women (and two men), centres around the proposition, that although these responses do not necessarily and directly correspond with either sex, the responses themselves have a lot of merit. It is revealed in my examination of contemporary novels from different parts of the world that rational/emotional responses relate, instead, to the particular situation of individuals-- advantaged/disadvantaged-- in different social and political structures. I have termed these responses masculine and feminine in my thesis, but have attempted to define masculinity and femininity as related to these socio-political situations, instead of being biologically determined. The definition of femininity in my thesis encompasses particular kinds of responses to various ideas such as cosmopolitan interactions between cultures and even beauty and shame. The novels that I look at in my thesis are: Kiran Desai’s The Inheritance of Loss, Toni Morrison’s Paradise, Zadie Smith’s On Beauty, Latife Tekin’s Dear Shameless Death, Salman Rushdie’s Shame, Kazuo Ishiguro’s Never Let Me Go, Kamila Shamsie’s Burnt Shadows, Chimamanda Ngozi Adichie’s Half of a Yellow Sun and Doris Lessing’s The Fifth Child and Ben, in the World. My argument is that by coming to a more or less general understanding of what I am regarding as the variously inflected feminine/disadvantaged position, it is possible to arrive at a coherent ethical value system that is directed to the margins of various social and political structure

Reliability- Based Stability Analysis of Slope

In Geotechnical engineering, the design and construction is done based on the Factor of Safety obtained from the deterministic approach. This Factor of safety doesn’t take into account the source and amount of uncertainty associated with the soil properties. Therefore, reliability based approach for the stability analysis has to be done to consider these uncertainties. In the present study, reliability-based stability analysis of slope has been made for using Finite Element Method, Upper bound Limit Analysis and Analytical method given by Low (1989). The commercially available software PLAXIS 2D-V9.02 is used for Finite Element Method and LimitState:GEO for Limit Analysis. The limit state function is developed using response surface methods. Full factorial design is used for development of response surface models. In this study, reliability analysis is done using first order reliability method. The need for reliability analysis and the corresponding reliability index and factor of safety is discussed. The study is validated by analyzing a case study of James Bay dykes. Parametric study has been done varying the soil and slope properties and modification has been made in the equation given by Low’s equation of Factor of Safety