419 research outputs found
Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final Report. Volume III: Silicon sheet: wafers and ribbons
The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development.
The primary objective of the Silicon Sheet Task of the FSA Project was the development of one or more low-cost technologies for producing silicon sheet suitable for processing into cost-eompetitive solar cells. Silicon sheet refers to high-purity crystalline silicon of size and thickness for fabrication into solar cells.
The Task effort began with state-of-the-art sheet technologies and then solicited and supported any new silicon sheet alternatives that had the potential to achieve the Project goals.
A total of 48 contracts were awarded that covered work in the areas of ingot growth and casting, wafering, ribbon growth, other sheet technologies, and programs of supportive research. Periodic reviews of each sheet technology were held, assessing the technical progress and the long-range potential. Technologies that failed to achieve their promise, or seemed to have lower probabilities for success in comparison with others, were dropped. A series of workshops was initiated to assess the state of the art, to provide insights into problems remaining to be addressed, and to support technology transfer.
The Task made and fostered significant improvements in silicon sheet including processing of both ingot and ribbon technologies. An additional important outcome was the vastly improved understanding of the characteristics associated with high-quality sheet, and the control of the parameters required for higher efficiency solar cells. Although significant sheet cost reductions were made, the technology advancements required to meet the Task cost goals were not achieved.
This FSA Final Report (JPL Publication 86-31, 5101-289, DOE/JPL 1012-125, October 1986) is composed of eight volumes, consisting of an Executive Summary and seven technology reports:
Volume I: Executive Summary.
Volume II: Silicon Material.
Volume III: Silicon Sheet: Wafers and Ribbons
Volume IV: High-Efficiency Solar Celis.
Volume V: Process Development.
Volume VI: Engineering Sciences and Reliability.
Volume VII: Module Encapsulation.
Volume VIII: Project Analysis and Integration.
Two supplemental reports included in the final report package are:
FSA Project: 10 Years of Progress, JPL Document 400-279. 5101-279, October 1985.
Summary of FSA Project Documentation: Abstracts of Published Documents, 1975 to 1986, JPL Publication 82-79 (Revision 1),5101-221, DOE/JPL-1 012-76, September 1986
Earth Observation Open Science and Innovation
geospatial analytics; social observatory; big earth data; open data; citizen science; open innovation; earth system science; crowdsourced geospatial data; citizen science; science in society; data scienc
ACUTA Journal of Telecommunications in Higher Education
In This This
The Strategic Accommodation of Change
Good Advice: Clean Out Your Closets (and More)
Making Decisions to Remove Legacy Cable
ADVERTORIAL: Best Practices for lP Telephony lmplementation
ADVERTORIAL: VolP Security: Myth or Reality?
ln-Room Phones: Nice or Necessary?
Voice and Network Department Convergence
Making Communications Accessible
lnstitutional Excellence Award: Sinclair Community College
Interview
President\u27s Message
From the Executive Director
Here\u27s My Advic
Active security vulnerability notification and resolution
The early version of the Internet was designed for connectivity only, without the
consideration of security, and the Internet is consequently an open structure. Networked
systems are vulnerable for a number of reasons; design error, implementation, and
management. A vulnerability is a hole or weak point that can be exploited to compromise
the security of the system. Operating systems and applications are often vulnerable because
of design errors. Software vendors release patches for discovered vulnerabilities, and rely
upon system administrators to accept and install patches on their systems. Many system
administrators fail to install patches on time, and consequently leave their systems
vulnerable to exploitation by hackers. This exploitation can result in various security
breaches, including website defacement, denial of service, or malware attacks. The overall
problem is significant with an average of 115 vulnerabilities per week being documented
during 2005.
This thesis considers the problem of vulnerabilities in IT networked systems, and maps the
vulnerability types into a technical taxonomy. The thesis presents a thorough analysis of
the existing methods of vulnerability management which determine that these methods
have failed to mange the problem in a comprehensive way, and show the need for a
comprehensive management system, capable of addressing the awareness and patch
deploymentp roblems. A critical examination of vulnerability databasess tatistics over the
past few years is provided, together with a benchmarking of the problem in a reference
environment with a discussion of why a new approach is needed. The research examined
and compared different vulnerability advisories, and proposed a generic vulnerability
format towards automating the notification process.
The thesis identifies the standard process of addressing vulnerabilities and the over reliance
upon the manual method. An automated management system must take into account new
vulnerabilities and patch deploymentt o provide a comprehensives olution. The overall aim
of the research has therefore been to design a new framework to address these flaws in the
networked systems harmonised with the standard system administrator process. The
approach, known as AVMS (Automated Vulnerability Management System), is capable of
filtering and prioritising the relevant messages, and then downloading the associated
patches and deploying them to the required machines.
The framework is validated through a proof-of-concept prototype system. A series of tests
involving different advisories are used to illustrate how AVMS would behave. This helped
to prove that the automated vulnerability management system prototype is indeed viable,
and that the research has provided a suitable contribution to knowledge in this important
domain.The Saudi Government and the Network Research Group at the University of Plymouth
XVIII International Coal Preparation Congress
Changes in economic and market conditions of mineral raw materials in recent
years have greatly increased demands on the ef fi ciency of mining production. This
is certainly true of the coal industry. World coal consumption is growing faster than
other types of fuel and in the past year it exceeded 7.6 billion tons. Coal extraction
and processing technology are continuously evolving, becoming more economical
and environmentally friendly. “ Clean coal ” technology is becoming increasingly
popular. Coal chemistry, production of new materials and pharmacology are now
added to the traditional use areas — power industry and metallurgy. The leading role
in the development of new areas of coal use belongs to preparation technology and
advanced coal processing. Hi-tech modern technology and the increasing interna-
tional demand for its effectiveness and ef fi ciency put completely new goals for the
University. Our main task is to develop a new generation of workforce capacity and
research in line with global trends in the development of science and technology to
address critical industry issues.
Today Russia, like the rest of the world faces rapid and profound changes
affecting all spheres of life. The de fi ning feature of modern era has been a rapid
development of high technology, intellectual capital being its main asset and
resource. The dynamics of scienti fi c and technological development requires acti-
vation of University research activities. The University must be a generator of ideas
to meet the needs of the economy and national development. Due to the high
intellectual potential, University expert mission becomes more and more called for
and is capable of providing professional assessment and building science-based
predictions in various fi elds.
Coal industry, as well as the whole fuel and energy sector of the global economy
is growing fast. Global multinational energy companies are less likely to be under
state in fl uence and will soon become the main mechanism for the rapid spread of
technologies based on new knowledge. Mineral resources will have an even greater
impact on the stability of the economies of many countries. Current progress in the
technology of coal-based gas synthesis is not just a change in the traditional energy markets, but the emergence of new products of direct consumption, obtained from
coal, such as synthetic fuels, chemicals and agrochemical products. All this requires
a revision of the value of coal in the modern world economy
Development of neutron resonance densitometry at the GELINA TOF facility
Neutrons can be used as a tool to study properties of materials and objects. An evolving activity in this field concerns the existence of resonances in neutron induced reaction cross sections. These resonance structures are the basis of two analytical methods which have been developed at the EC-JRC-IRMM: Neutron Resonance Capture Analysis (NRCA) and Neutron Resonance Transmission Analysis (NRTA). They have been applied to determine the elemental composition of archaeological objects and to characterize nuclear reference materials.
A combination of NRTA and NRCA together with Prompt Gamma Neutron Analysis, referred to as Neutron Resonance Densitometry (NRD), is being studied as a non-destructive method to characterize particle-like debris of melted fuel that is formed in severe nuclear accidents such as the one which occurred at the Fukushima Daiichi nuclear power plants. This study is part of a collaboration between JAEA and EC-JRC-IRMM.
In this contribution the basic principles of NRTA and NRCA are explained based on the experience in the use of these methods at the time-of-flight facility GELINA of the EC-JRC-IRMM. Specific problems related to the analysis of samples resulting from melted fuel are discussed. The programme to study and solve these problems is described and results of a first measurement campaign at GELINA are given.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard
NASA Tech Briefs, December 1999
Topics include: Imaging/Videos/Cameras; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Books and Reports
Self-adaptation via concurrent multi-action evaluation for unknown context
Context-aware computing has been attracting growing attention in recent years. Generally, there are several ways for a context-aware system to select a course of action for a particular change of context. One way is for the system developers to encompass all possible context changes in the domain knowledge. Other methods include system inferences and adaptive learning whereby the system executes one action and evaluates the outcome and self-adapts/self-learns based on that. However, in situations where a system encounters unknown contexts, the iterative approach would become unfeasible when the size of the action space increases. Providing efficient solutions to this problem has been the main goal of this research project.
Based on the developed abstract model, the designed methodology replaces the single action implementation and evaluation by multiple actions implemented and evaluated concurrently. This parallel evaluation of actions speeds up significantly the evolution time taken to select the best action suited to unknown context compared to the iterative approach.
The designed and implemented framework efficiently carries out concurrent multi-action evaluation when an unknown context is encountered and finds the best course of action. Two concrete implementations of the framework were carried out demonstrating the usability and adaptability of the framework across multiple domains.
The first implementation was in the domain of database performance tuning. The concrete implementation of the framework demonstrated the ability of concurrent multi-action evaluation technique to performance tune a database when performance is regressed for an unknown reason.
The second implementation demonstrated the ability of the framework to correctly determine the threshold price to be used in a name-your-own-price channel when an unknown context is encountered.
In conclusion the research introduced a new paradigm of a self-adaptation technique for context-aware application. Among the existing body of work, the concurrent multi-action evaluation is classified under the abstract concept of experiment-based self-adaptation techniques
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