Natural & Applied Sciences

Research Papers/Topics Natural & Applied Sciences

A New Approach to the Analysis of Forward Bias Dark Current Characteristics of a-Si:H Solar Cells

Generally the dark forward bias current voltage (JD-V) characteristics of a-Si:H solar cells are analyzed without clearly separating their contributions due to carrier recombination in the bulk from that at the p/i interface regions nor those imposed by carrier injection from the p and n contacts. Furthermore their exponential regimes are interpreted and fitted with constant diode quality factor n with modeling which is based on many fitting parameters that have not been reliably established....

Evolution of microstructure and phase in amorphous, protocrystalline, and microcrystalline silicon studied by real time spectroscopic ellipsometry

Real time spectroscopic ellipsometry has been applied to develop deposition phase diagrams that can guide the fabrication of hydrogenated silicon (Si: H) thin films at low temperatures (< 300° C) for highest performance electronic devices such as solar cells. The simplest phase diagrams incorporate a single transition from the amorphous growth regime to the mixed-phase (amorphous+ microcrystalline) growth regime versus accumulated film thickness [the a→(a+ μc) transition].

Compound Parabolic Concentrators for Solar Water Heat Pasteurization: Numerical Simulation

Many people in less developed countries drink water with microbial contamination, which leads to the annual death of 5 million children. Although some people currently boil water, all microbes that cause disease in humans do not survive at temperatures >65oC, which solar water pasteurizers can easily produce. These pasteurizers are similar to box solar cookers, and typically have a small rectangular reflector. The objective of this work is to calculate the increase in output due to compound p...

Teaching Science by Encouraging Innovation in Appropriate Technologies for Sustainable Development

Appropriate technologies, those able to be easily and economically constructed from readily available materials by local craftspeople, have a central role in the alleviation of poverty in the developing world. Research and development of these technologies are, however, generally apportioned relatively modest support by the developed world’s institutions in part because the operation of many of these appropriate technologies is dependent on relatively well-understood science accessible even...

Teaching Physics Using Appropriate Technology Projects

Appropriate technologies able to be easily and economically constructed from readily available materials by local craftspeople have a central role in the alleviation of poverty in the developing world. However, research and development of these technologies are generally apportioned relatively modest support by the developed world’s institutions, in part because the operation of many of these appropriate technologies is dependent on relatively well-under-stood science accessible even to int...

Foreign Languages and the Environment: A Collaborative Instructional Project

The project described here—a collaborative venture between Modern Languages and Physics—provided an opportunity for students to increase their language proficiency while learning about concepts related to the environment. The Standards for Foreign Language Learning, and in particular the “Connections” goal, call for foreign language educators to integrate language instruction into other disciplines, while the “Communities” goal advocates using the language beyond the classroom. In...

Appropedia as a Tool for Service Learning in Sustainable Development

Numerous studies have demonstrated that university students are capable of contributing to sustainable development while improving their academic skills. Unfortunately for many institutions, the expense of sending large cohorts of students on international service learning trips is prohibitive. Yet, students remain enthusiastic and well equipped to assist in sustainable development. This article reports on two pedagogical experiments in service learning that overcame this challenge by providi...

Utilization of Virtual Globes for Open Source Industrial Symbiosis

Several proprietary industrial symbiosis software tools have been developed, however, without long term financial commitments these endeavors fall short of creating generalizable and sustainable tools. The recent development of virtual globes such as Google Earth (GE), an information service that provides imagery and three dimensional data depicting the entire physical earth, provides an opportunity to use a new sustainable method of navigating information to save energy and use materials mor...

Overcoming Technical Constraints for Obtaining Sustainable Development with Open Source Appropriate Technology

Open source appropriate technology (OSAT) refers to technologies that provide for sustainable development while being designed in the same fashion as free and open-source software. Facilitated by advances in information technology software and hardware, new ways to disseminate information such as wikis and Internet-enabled mobile phones, the global development of OSAT has emerged as a reality. This paper shows the sharing of design processes, appropriate tools, and technical information is en...

Overcoming Language Challenges of Open Source Appropriate Technology for Sustainable Development in Africa

Despite enormous efforts over the course of several decades, sustainable development on the African continent remains incompletely realized. Top-down methodologies have largely failed and many sustainable development organizations now support small-scale direct approaches, which provide the tools and knowledge necessary for people to help themselves. The new approach to sustainable development of open source appropriate technology (OSAT) builds on these successes. OSAT is a development method...

Open Design-Based Strategies to Enhance Appropriate Technology Development

The appropriate technology (AT) movement is being driven by inventors and innovators who are interested in designing technologies that are culturally, environmentally, and economically appropriate, and feasible to construct and use for people anywhere in the world. This paper examines how open sharing of designs, specifications, and technical information can enhance effectiveness, widespread use, and innovation of AT. This commons-based open design method has been highly successful for softwa...

Hybrid Virtual- and Field Work-based Service Learning with Green Information Technology and Systems Projects

Traditional engineering service learning (SL) projects can be classified as: 1) collaborations with a community group or non-profit organization to provide specific engineering around a community need, or 2) an internship-like experience with industry to address work requested by a client. The limitation of both traditional SL approaches is that they do not prepare students to implement unprescribed projects. In contrast, here students chose both the project and the partner for a self-directe...

Viability of Small-Scale Arsenic-Contaminated Water Purification Technologies for Sustainable Development in Pakistan

Drinking arsenic-contaminated water leads to a series of health problems that has limited development for the largely poor rural people of Pakistan who are unable to afford bottled water, centralized treatment plants, or expensive water filter systems. This paper reviews the available appropriate technologies for the removal of arsenic in drinking water to assist in just sustainable development in Pakistan. Several technologies were found to be both technically- and economically- viable and s...

Barriers to Appropriate Technology Growth in Sustainable Development

Given the urgency of development problems world-wide, as well as the opportunities of open source appropriate technology (OSAT) to help expedite sustainable development goals, a better understanding of the barriers limiting the scaling of OSAT is needed. In this study, key organizations and researchers working in the field of appropriate technology (AT) were interviewed to identify barriers to OSAT. The data was analyzed via pattern coding and content analysis. Results reveal that among the m...

Effects of Substrate Temperature on Indium Gallium Nitride Nanocolumn Crystal Growth

Indium gallium nitride films with nanocolumnar microstructure were deposited with varying indium content and substrate temperatures using plasma-enhanced evaporation on amorphous SiO2 substrates. FESEM and XRD results are presented, showing that more crystalline nanocolumnar microstructures can be engineered at lower indium compositions. Nanocolumn diameter and packing factor (void fraction) was found to be highly dependent on substrate temperature, with thinner and more closely packed nanoco...


7216 - 7230 Of 8856 Results
@