Major Trends in Operating Systems Development

Operating systems have changed in nature in response to demands of users, and in response to advances in hardware and software technology. The purpose of this paper is to trace the development of major themes in operating system design from their beginnings through the present. This is not an exhaustive history of operating systems, but instead is intended to give the reader the flavor of the dif ferent periods in operating systems\u27 development. To this end, the paper will be organized by topic in approximate order of development. Each chapter will start with an introduction to the factors behind the rise of the period. This will be fol lowed by a survey of the state-of-the-art systems, and the conditions influencing them. The chapters close with a summation of the significant hardware and software contributions from the period

History of the numerical aerodynamic simulation program

The Numerical Aerodynamic Simulation (NAS) program has reached a milestone with the completion of the initial operating configuration of the NAS Processing System Network. This achievement is the first major milestone in the continuing effort to provide a state-of-the-art supercomputer facility for the national aerospace community and to serve as a pathfinder for the development and use of future supercomputer systems. The underlying factors that motivated the initiation of the program are first identified and then discussed. These include the emergence and evolution of computational aerodynamics as a powerful new capability in aerodynamics research and development, the computer power required for advances in the discipline, the complementary nature of computation and wind tunnel testing, and the need for the government to play a pathfinding role in the development and use of large-scale scientific computing systems. Finally, the history of the NAS program is traced from its inception in 1975 to the present time

Chemical History with a Nuclear Microprobe

A nuclear microprobe cannot give direct information on the chemical state of an element, but the spatial distribution of elements in a specimen is often determined by the chemical history of the sample. Fuel cells and minerals are examples of complex systems whose elemental distributions are determined by past chemical history. The distribution of catalyst in used fuel cell electrodes provides direct information on the chemical stability of dispersed catalysts under operating conditions. We have used spatially resolved Rutherford backscattering to measure the migration of platinum and vanadium from intermetallic catalysts and to determine their suitability for use under the extreme operating conditions found in phosphoric acid fuel cells. Geologic materials are complex, heterogeneous samples with small mineral grains. The trace element distribution within the individual mineral grains and between different mineral phases is sensitive to the details of the mineral formation and history. The spatial resolution and sub-100-ppm sensitivity available with a nuclear microprobe open up several new classes of experiments to the geochemist. Geochemistry and electrochemistry are two areas proving particularly fruitful for application of the nuclear microprobe

Effective Treatment Options for Acid Mine Drainage in the Coal Region of West Virginia

Coal mining has a long history in the state of West Virginia and until recently mining was unregulated. Due to this history there are several legacy problems of the mining industry being dealt with today. Acid mine drainage (AMD) is one of the major legacy problems being combated today in the state. AMD is the product of oxidation in abandoned mine lands and runs into surface water. There are treatment sites all over the state to combat this problem. This thesis research looks the AMD problem in West Virginia and at the effectiveness of the treatment systems that are currently operating in the state. Data for each treatment site include treatment used, cost, load reduction of acidity, and metal load reduction. The data come from the various public and private agencies that manage that particular site. This data was used in GIS and statistical operations to show were AMD is a problem and the effectiveness, both overall and by cost, of the treatments that are being used by the state. AMD source data show that there is a widespread problem in the state that is not going away. It was found that in comparison to the other treatment types in use anoxic limestone drains, open limestone channels, and land reconstruction are the most effective for reduction of acidity and metals

Impacts of the Erosion of State Funding for Public Higher Education: Longitudinal Case Studies of Four State Systems – California, Georgia, New York and Wisconsin

The rising cost of higher education in America is national news on a regular basis and many feel that as the costs increase the American dream of upward mobility slips further and further out of reach. Much of the research on higher education to date focuses on the quantifiable changes in support for public colleges and universities at the national or state levels, but less is written about individual state public higher education systems. This study provides a fifty-year, fifty-state history of funding for the operating costs of higher education and new information, from the four quadrants of the country, illustrating the impacts of state appropriations, access and cost of attendance on degree production. This longitudinal study of four states’ public university systems – California State University (CSU), University System of Georgia (USG), City University of New York (CUNY), and University of Wisconsin System (UWS), over the period of 1990 to 2010, answers the following questions: Has access to higher education in each of the four states changed over the twenty-year span, both in aggregate and for specific minority groups (Blacks and Hispanics)? What variables best explain differences in degree production at each of the public higher education systems between 1990 and 2010? And to what extent is variance in degree production explained at the system level or institution? Three constructs: state support, access, and cost of attendance are used to answer these questions. The most significant impact of the erosion of state funding for public higher education is the substantial shift from states providing operating funds for higher education to students and their families paying a large share of the costs. A comparative look at the four state systems found the split between state appropriations and tuition revenue narrowed significantly over the twenty years; specifically, the ratio of state appropriations to tuition revenue dropped 52% to 67% across the four systems. Additionally, degree production at each of the four systems was most affected by state appropriations, in-state tuition, state financial aid and Pell amounts awarded. Furthermore, the two systems (USG and CUNY) with funding agreements at the state level had greater increases in degrees per capita than the two other systems. Data for this study was gathered from public documents and reports, available on each state system’s webpages, from the Integrated Postsecondary Education Data System (IPEDS - NCES), and from Grapevine, an annual compilation of data on state fiscal support for higher education collected by the Center for the Study of Education Policy at Illinois State University and the State Higher Education Executive Officers (SHEEO). The findings from this study cannot be used to generalize funding, enrollment and degrees awarded per capita in other states, but rather provide an analytical framework of historic support for public higher education and offers guidance for developing arguments to influence investments in postsecondary public education

Atlantic Shore Line Railway: its predecessors and its successors

Introduction The 1949 SALE of the 3-mile electric freight line between Sanford and Springvale, Maine, to the Sanford & Eastern Railroad by the York Utilities Company, and subsequent changeover to Diesel motive power, all but brings to an end the colorful history of the second largest of the Pine Tree State\u27s four major electric railway systems -- the Atlantic Shore Line Railway -- known in its heyday as the Sea View Route. The Sanford-Springvale line was the last remaining segment under trolley wire. At its height, this extensive 90-mile network of cross-country trolley lines, operating largely over private right-of-way, extended from Kittery to Biddeford, serving York, York Beach, Ogunquit, Wells, Kennebunk, Kennebunkport and Cape Porpoise; it branched inland from Kennebunk to Sanford and Springvale, and connected both Kittery and York with Eliot and South Berwick (Maine) and Dover (New Hampshire), as well as operating the ferry service across the Piscataqua River between Kittery, Maine, and Portsmouth, New Hampshire.https://digicom.bpl.lib.me.us/books_pubs/1029/thumbnail.jp

Water Allocation Mechanisms: Principles and Examples

From the earliest times, water resources have been allocated on the basis of social criteria - maintaining the community by ensuring that water is available for human consumption, for sanitation, and for food production. Societies have invested capital in infrastructure to maintain this allocation. Yet social change, including changes in (and more understanding of) how goods are distributed, has produced new issues in water allocation. Population growth has made water scarcity a major problem in many countries and water pollution, while by no means a recent problem, is more widespread than ever before. Traditionally the state has played a dominant role in managing water resources, but inefficient use of water, poor cost recovery for operating and maintenance expenses, the mounting cost of developing new water sources, and problems with the quality of service in agency-managed systems has led to a search for alternatives that make water allocation and management more efficient. The authors address some of the basic principles of treating water as an economic good and of allocating it among the sectors. After outlining the economic principles behind allocating scarce water resources, they review the actual means of various mechanisms used for allocating water, including marginal cost pricing, social planning, user-based allocation, and water markets. Giving examples from experience in several countries, they weigh the pros and cons of different approaches to water allocation, showing that no single approach is suitable for all situations. Clearly that state must play an important regulatory role, for example, but how effectively it does so depends on the relative political influence of various stakeholders and segments of society. User-based allocation is generally more flexible than state allocation, but collective action is not equally effective everywhere; it is most likely to emerge where there is strong demand for water and a history of cooperation. The outcome of market allocation depends on the economic value of water for various uses, but moving toward tradable property rights in water may ease the process of intersectoral reallocation by compensating the"losers"and creating incentives for efficient water use in all sectors

Learning for predictions: Real-time reliability assessment of aerospace systems

Prognostics and Health Management (PHM) aim to predict the Remaining Useful Life (RUL) of a system and to allow a timely planning of replacement of components, limiting the need for corrective maintenance and the down time of equipment. A major challenge in system prognostics is the availability of accurate physics based representations of the grow rate of faults. Additionally, the analysis of data acquired during flight operations is traditionally time consuming and expensive. This work proposes a computational method to overcome these limitations through the dynamic adaptation of the state-space model of fault propagation to on-board observations of system’s health. Our approach aims at enabling real-time assessment of systems health and reliability through fast predictions of the Remaining Useful Life that account for uncertainty. The strategy combines physics-based knowledge of the system damage propagation rate, machine learning and real-time measurements of the health status to obtain an accurate estimate of the RUL of aerospace systems. The RUL prediction algorithm relies on a dynamical estimator filter, which allows to deal with nonlinear systems affected by uncertainties with unknown distribution. The proposed method integrates a dynamical model of the fault propagation, accounting for the current and past measured health conditions, the past time history of the operating conditions (such as input command, load, temperature, etc.), and the expected future operating conditions. The model leverages the knowledge collected through the record of past fault measurements, and dynamically adapts the prediction of the damage propagation by learning from the observed time history. The original method is demonstrated for the RUL prediction of an electromechanical actuator for aircraft flight controls. We observe that the strategy allows to refine rapid predictions of the RUL in fractions of seconds by progressively learning from on-board acquisitions

Predicting System Accidents with Model Analysis During Hybrid Simulation

Standard discrete event simulation is commonly used to identify system bottlenecks and starving and blocking conditions in resources and services. The CONFIG hybrid discrete/continuous simulation tool can simulate such conditions in combination with inputs external to the simulation. This provides a means for evaluating the vulnerability to system accidents of a system's design, operating procedures, and control software. System accidents are brought about by complex unexpected interactions among multiple system failures , faulty or misleading sensor data, and inappropriate responses of human operators or software. The flows of resource and product materials play a central role in the hazardous situations that may arise in fluid transport and processing systems. We describe the capabilities of CONFIG for simulation-time linear circuit analysis of fluid flows in the context of model-based hazard analysis. We focus on how CONFIG simulates the static stresses in systems of flow. Unlike other flow-related properties, static stresses (or static potentials) cannot be represented by a set of state equations. The distribution of static stresses is dependent on the specific history of operations performed on a system. We discuss the use of this type of information in hazard analysis of system designs