Device characterization of cadmium telluride photovoltaics

2014 Summer.Thin-film photovoltaics have the potential to make a large impact on the world energy supply. They can provide clean, affordable energy for the world. Understanding the device physics and behavior will enable increases in efficiency which will increase their impact. This work presents novel approaches for evaluating efficiency, as well as a set of tools for in-depth whole-cell and uniformity characterization. The understanding of efficiency losses is essential for reducing or eliminating the losses. The efficiency can be characterized by a breakdown into three categories: solar spectrum, optical, and electronic efficiency. For several record devices, there is little difference in the solar spectrum efficiency, modest difference in the optical efficiency, and large difference in the electronic efficiency. The losses within each category can also be further characterized. The losses due to the broad solar spectrum and finite temperature are well understood from a thermodynamic physics perspective. Optical losses can be fully characterized using quantum efficiency and optical measurements. Losses in fill factor can be quantified from series and shunt resistance, as well as the expected fill factor from the measured V oc and A. Open-circuit voltage losses are the most significant, but are also be the hardest to understand, as well as the most technology-dependent. Characterization of the whole cell helps to understand the behavior, performance, and properties of the cell. Several different tools can be used for whole-cell characterization, including current-voltage, quantum efficiency, and capacitance measurements. Each of these tools give specific information about the behavior of the cell. When combined, they can lead to a more complete understanding of the cell performance than when taken individually. These tools were applied to several specific CdTe experiments. They have helped to characterize the baseline performance of both the deposition tool and the measurement systems. Characterization of plasma-cleaned cells show an improvement in performance, even at thinner CdS layer thickness. Measurements of thinning CdTe samples reveal additional optical losses, likely caused by the increasing importance of the back diode. Characterization of Cd(S,O) devices show improved performance, both from improved optical properties and theorized improvement in band alignment properties. Uniformity can have an effect on whole-cell performance, but can also be an important parameter to characterize on its own. Light-beam-induced current is a powerful tool for characterizing uniformity. The LBIC tool was upgraded to improve its accuracy, functionality, and speed. The improved LBIC system aids in the collection of uniformity data. A number of parameters can be varied to provide in-depth uniformity information and help identify causes of nonuniformity. The wavelength can be varied to provide information on different layers. This can help identify variations in CdS thickness and local CdTe band gap. An applied voltage bias can be used to identify locations with weak diode properties. The resolution can also be varied to provide information on nonuniformities at different scales, from variations across the whole cell to variations on the size of several grains. LBIC can also be paired with electroluminescence to create a powerful nonuniformity characterization suite. The two can be paired with EL used as a screening tool to identify cells or areas which need further characterization from LBIC

The home environments of children with disabilities: implications for peer relationships and self-determination

The research reported here explores the role of the home environment in the development of peer relationships and skills contributing to self-determination for children with disabilities. More specifically, the roles that parents and the physical environment play in regulating peer relationships and providing opportunities to exert control, make choices and act independently in the home are examined. A literature review and two research studies examining the home environments of children with disabilities are presented;The first study uses qualitative data analysis of in-depth family interviews and home observations to examine the experiences children with disabilities have with peers in the home environment. Results indicate many children with disabilities spend limited time with peers in the home environment. Parents of children with disabilities, parents of peers of children with disabilities, peers of children with disabilities, characteristics of the disability, and characteristics of the home and neighborhood are identified as contributors to the opportunities children with disabilities have to interact with peers. Recommendations for increasing opportunities for children with disabilities to interact with peers in the home environment are provided;The second study presents findings from the In-Home Checklist (INHC), a series of questions assessing the amount of access and control children with disabilities experience in the home, and the Parent Attitude Survey (PAS), an instrument designed to measure parents\u27 attitudes towards self-determination. Case studies from in-depth family interviews and home observations add depth to the information reported from the INHC and PAS. Results indicate parents of children with disabilities value the development of self-determination in their children with disabilities. However, many children in this sample had limited opportunities to develop these skills in the home environment. Parent attitudes towards self-determination, and the severity of the disability were both related to children\u27s opportunities to make choices, act independently, and interact with peers in the home environment. Ways that professionals working with families of children with disabilities can help parents structure the home environment to support the development of self-determination in their children are explored

A Hemimysis Driven Novel Ecosystem at a Modified Boulder Breakwall

The US Army Corps of Engineers (USACE) is mandated to maintain and repair aging breakwall structures in all commercial ports on the Great Lakes. In May of 2014, the construction of Milwaukee Harbor USACE “green” breakwall (GBW) reconciliation created complex rocky aquatic habitat by depositing cobble-sized stone as a veneer over standard 6-10 ton boulders, thus creating “control” (boulder) and “treatment” (cobble) habitats. The breakwall is home to a prolific population of Hemimysis anomala, the introduced Ponto-Caspian mysid, which is significantly more abundant on cobble versus boulders (p\u3c0.05, using a novel trap for Hemimysis). Fish and forage communities were sampled in 2015 and 2016 using a combination of experimental and micromesh gill nets, night scuba diving surveys, and a novel Hemimysis trap. This nearshore lithophilic mysid appears to provide a significant new seasonal food resource in the Milwaukee Harbor for pelagic prey fishes during inshore spawning migrations and upwelling events. Alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) fed heavily on Hemimysis with some individuals consuming hundreds of mysids. Night scuba diving surveys and gill netting confirmed that rainbow smelt preferred to forage on the cobble section (p\u3c0.05), and also consumed more Hemimysis there than they did at the control breakwall site (p\u3c0.05). Hemimysis were also the primary food item consumed by nearshore game fishes such as YOY yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris) caught at the breakwall. This study provides the first documented evidence that where abundant in the Laurentian Great Lakes, Hemimysis do have the ability to significantly impact local food webs and drive the feeding ecology of both pelagic transient and nearshore resident fishes

Simulation Game Concept For AI-Enhanced Teaching Of Advanced Value Stream Analysis and Design

Value stream analysis and design is employed globally by improvement teams within industrial settings to maximize value creation and eliminate waste. For ending methodical time-centricity, research expanded the methodology to incorporate diverse facets like material flow cost accounting, information logistics, and external influence factors. These enhancements, along with increasing data volumes, are prompting a re-evaluation of how professional improvement teams should think and operate. Consequently, a transformation of the pedagogical approach used for educating students and professionals necessitates novel solutions. Conventional teaching methods such as expository lectures are widely considered inadequate in promoting knowledge retention and engagement. So far, existing research has not yet resulted in a solution that can effectively impart the methodological complexity of advanced value stream analysis and design in a motivating and vivid fashion. To address this gap, this paper applies a tailored CRISP gamification framework to develop a simulation game concept. These concept enables AI-enhanced teaching of advanced value stream analysis and design focusing on identification of multi-stage resource-efficient optimization strategies. Through integration of game-based learning with AI a trained reinforcement learning agent can act either competitively or cooperatively, creating a unique form of teaching accounting the aspects personalization, adaptive feedback, content creation, and analysis and assessment

On line microwave based monitor of carbon in fly ash

The amount of carbon in fly ash reveals much information about coal combustion efficiency and the quality of fly ash as a marketable product. The current standard for measuring the amount of carbon in fly ash is the manual lesson-ignition (LOI) test. The goal of this research is to increase the strength of the photoacoustic signal by changing the sampling technique and the microwave radiation source while maintaining a signal that is independent of particle size and maintaining them correlation between signal strength and carbon content of fly ash. The sampling technique was changed from isokinetic sampling to cyclonic concentration of fly ash, which results in a higher concentration of fly ash moving through the photoacoustic cell, to a closed loop fly ash handling system that simulates the flow of fly ash from cyclonic concentration. The microwave source was changed from a 600 W modified microwave oven (f =2.45 GHz), to a tunable solid-state microwave generator, this was done to eliminate problems experienced with the modified microwave oven of modulation frequency drift and power fluctuations. It is important to maintain a signal that is independent of particle size because changing conditions in the combustor bed can result in fluctuations in fly ash particle size. Maintaining the correlation between signal strength and carbon content of fly ash is the ultimate goal of this research

Towards Digital Solutions For Value Stream Analysis and Design: Systematic Literature Review And Market Analysis

Recognized as a core element of lean management practice, value stream analysis and design is widely adopted by improvement teams in industrial settings to optimize value creation and eliminate waste. The advancement of value stream analysis and design, incorporating elements such as material flow cost accounting, information logistics, and external influential factors, requires change how improvement teams should think and operate. Emerging complexity of method application and the rise in data volumes underscores the need for novel workflows and the necessity for digital solutions that empower improvement teams in their duties. While existing research focuses on conceptual design of digital solutions, recently no systematic analysis of concepts and solutions from research and practice regarding core aspects of value stream analysis and design has been conducted. To address this research gap, this paper adapts a three-phase research design within a y-model structured process. A systematic literature review and a market analysis are conducted to identify digital solutions for value stream analysis and design. Solutions are showcased and evaluated via concept matrices. Contributing findings of this paper are an assessment of selected concepts form research and solutions from practice as well as the deduction of research-focused requirements, practice-focused requirements, and currently neglected requirements

Friendships of children with disabilities in the home environment

Friendships are a valued aspect of life. Understanding the family and home aspects of friendships can help special educators to develop a broader understanding of issues supporting friendships for young children with disabilities. In this exploratory study, family interviews and home observations were used to examine friendships of children with disabilities (3 to 10 years old) at home. Results suggest many children with disabilities spend limited time with friends or peers in the home environment. In this sample, children with the greatest amount of contact with friends had disabilities that were mainly physical in nature, while children with behavior problems and cognitive limitations were among the children who experienced the fewest peer interactions. Children living in isolated areas and/or off busy roads had more limited contact with friends than children residing in neighborhoods. Living in close proximity of other children, however, did not guarantee frequent peer interactions or friendships. Characteristics of the home and neighborhood and parents\u27 roles in initiating and supervising friendships are examined. Implications for special educators are discussed for increasing opportunities for children with disabilities to interact with peers and develop friendships in their home and neighborhood

Towards Digital Solutions For Value Stream Analysis and Design: Investigating Enterprise Perspective Requirements

Value stream analysis and design is considered as a central element of lean management, globally utilized by improvement teams within industrial contexts to maximize value creation and eliminate waste. The advancement of value stream analysis and design, including material flow cost accounting, information logistics, and external factors, is shifting how improvement teams operate due to growing complexity and data volumes. Required novel workflows pull the need for digital solutions that empower improvement teams. While existing research primarily focuses on conceptualizations of solutions, there has been no derivation of real-world requirements from an enterprise perspective. To address this research gap, this paper adapts a mixed methods approach with exploratory sequential design. Initially, a qualitative interview series with nine lean management experts from different industry-related enterprises in Germany was conducted. Over 250 transcribed minutes of interviews were evaluated qualitatively and structurally. Subsequently, identified enterprise requirements were quantitatively instigated functional and dysfunctional utilizing a kano questionnaire; answered by 33 German participants with lean management background. Contributing findings of this paper are 15 enterprise requirements for digital solution development, alongside a more detailed analysis of these requirements based on their ability to systematically satisfy customer needs and mitigate dissatisfaction