Differential Power Processing Converter Design for a Photovoltaic-Powered Charging Bag

Department of Electrical EngineeringTraditional photovoltaic (PV) systems are stationary PV systems mounted in one location and, generally, receive consistent and even illumination across the PV panels. However, solar photovoltaic (PV) power is also getting widely used in lower-power emerging applications, like wearables or internet of things (IoT) devices. One fundamental challenge of using PV power in wearable applications is that individual PV cells may be pointing in different angles, receiving different light intensities. Under these uneven illumination, resulting system efficiency depends on the configurations of the PV cells and converters. Through this thesis, the system efficiencies of five configurations are compared with nine realistic test cases. The five configurations are: PV in series with central converter, PV in parallel with central converter, PV with cascaded converters, PV in series with differential power processing (DPP) converters, and PV in parallel with DPP converters. The nine test cases are composed of an ideal case (all PV cells at 1,000 W/m2) and eight realistic illumination cases based on the weather (sunny or cloudy) and realistic usage scenarios. Based on these cases the system efficiency is calculated for each configuration considering a range of converter efficiencies (70% to 100%). Results show that the parallel DPP configuration shows the highest system efficiency in all cases. Parallel DPP converters can achieve individual PV control and maximizing output power by processing small fraction of the PV power. There are two types of parallel DPP architectures which are with and without a front-end converter. Two parallel DPP architectures are analyzed and compared for a target 5-W wearable application. Between the two architectures, the DPP system without a front-end converter shows consistently high performance and operates properly over a wider range of lighting conditions. Therefore, the proper operation, such as maximum power point tracking (MPPT) of PV cells, using parallel DPP converters without the front-end converter is validated through simulation and hardware experiments. The PV-powered wearable prototype is able to charge a portable battery under low-light and partial shading conditions.ope

Ever-Changing Mind

Everything around us is changing fast. We sometimes find ourselves feeling confused and fragile in this world. The purpose of the design was to reflect our ever-changing minds. We created various images of the textile designs that express different emotional statuses, and then displayed them in a blank dress

Design Considerations for Parallel Differential Power Processing Converters in a Photovoltaic-Powered Wearable Application

Solar photovoltaic (PV) power is a widely used to supply power to the electric grid but can also be used in lower-power emerging applications, like in wearables or the internet of things. One fundamental challenge of using PV power in flexible wearable applications is that individual PV modules point at various angles, thus receiving different light intensities. Using a series configuration for the PV modules greatly decreases power utilization under uneven irradiance conditions. Parallel differential power processing (DPP) converters are employed to address this power reduction problem, while maintaining individual PV control and maximizing output power. Two parallel DPP configurations, with and without a front-end converter, are analyzed and compared for a target battery-charging application. The DPP system without a front-end converter shows consistently high performance and operates properly over a wider range of lighting conditions. Maximum power point tracking (MPPT) algorithms are also examined for parallel DPP systems. When the MPPT parameters are properly calibrated, simulation results indicate that voltage-offset resistive control is the most effective at maximizing PV power under unbalanced lighting conditions

Is Emotion Regulation the Key to Breaking the Cycle of Violence? The Roles of Emotion Regulation in Buffering the Effects of a Childhood History of Maltreatment on Intimate Partner Violence in Emerging Adulthood

Extant literature has demonstrated that having adverse childhood experiences (e.g., child maltreatment, domestic violence, etc.) would place trauma survivors at high risk for experiencing emotion dysregulation and violence later in life. While a sizable body of literature has investigated direct effects and indirect effects of a history of childhood maltreatment on experiences of intimate partner violence (IPV) in adulthood, only a few studies have tested the mediating effect of emotion dysregulation on the relationship between a history of childhood maltreatment and IPV exposure in adulthood. Particularly, since the pathways from a history of childhood maltreatment to experiences of IPV in adulthood have been primarily examined in cross-sectional studies, little is known about the long-term effects of childhood experiences of maltreatment on the trajectories of IPV exposure in emerging adulthood, in which the rate of IPV is the highest in adulthood. In addition, most of these studies examined only a single type and form of IPV. To fill this gap, the current study conducted secondary data analysis using data from the Pittsburgh Girls Study (PGS), which is a longitudinal survey of an urban community sample of girls. Latent growth curve modeling was used to examine the direct effects of a history of childhood maltreatment on risk of both IPV perpetration and victimization over time and to test whether these effects would be mediated by emotion dysregulation. The results of the study indicated that a history of childhood maltreatment was significantly associated with an initial level of risk for IPV exposure. Importantly, a history of childhood emotional abuse was significantly associated with a higher level of emotion dysregulation, which in turn increased the initial levels of risk for IPV exposure. These significant findings on the mediating effect of emotion dysregulation suggest important implications for social work practice. Specifically, it is critical for social workers to early identify the population who have a history of childhood emotional abuse and provide them with interventions targeting emotion dysregulation, thereby protecting them from later exposure to IPV

Animal ownership in low-income households: Is here a relationship between human and animal food insecurity?

This study examined the relationship between owning a pet and experiencing food insecurity in low-income households using self-administered surveys (N=392) and in-depth interviews (N=15). The study found that low-income pet owners were not at greater risk for being food insecure. In fact, having a pet associated with better food security than when people did not own a pet. The cross-sectional design limits causal explanation. It is possible that people who are very food insecure choose not to accept stray animals into their homes or do not adopt or re-home animals from shelters or family members (typically how owners acquired pets). However, another explanation supported by the interviews is that having a pet or pets activates or motivates people to manage their food needs and to work harder at keeping food on the table and in the bowl. Owners may be activated or motivated to do things such as go to the pantry and manage the household finances so that they can continue to care for their pets. Moreover, having a pet provides emotional and social support benefits, particularly for older adults and those with disabilities. Pets give a sense of routine and for dog owners, motivate physical exercise. However, owners did share their human food when they did not have pet-food. Other potential deleterious impacts were grief following the death of beloved pets and financial concerns about current and future veterinary care