EVALUATING SCHEDULING METHODS FOR ENERGY COST REDUCTION IN A HETEROGENEOUS DATA CENTER ENVIRONMENT

Over the past two decades the rise of information technologies (IT) has enabled businesses to communicate, coordinate, and cooperate in unprecedented ways. However, this did not come without a price. Today, IT infrastructure accounts for a substantial fraction of the national energy consumption in most advanced countries. Subsequently, research turned to finding ways of making IT more sustainable and lessening the environmental impact of IT infrastructure. In our previous work we developed LINFIX, an innovative method for handling the scheduling problem in data centers, which substantially reduced the total energy consumption compared to commonly used practices. Due to the computational complexity of the scheduling problem, we were, however, unable to estimate the cost reduction of LINFIX compared to what is theoretically possible. In this work we employ a genetic algorithm to provide a benchmark to better assess the quality of the LINFIX solutions. While the genetic algorithm frequently finds better solutions, the additional average cost reduction when compared to LINFIX is less than 0.1 percent. Taking the computational speed into account, this confirms our hypothesis that LINFIX provides very energy efficient scheduling plans in short time

The development of cryogenic storage systems for space flight

Development of cryogenic storage systems for manned space fligh

Energy harvesting of low-grade waste heat with colloid based technology

L'abstract è presente nell'allegato / the abstract is in the attachmen

A study of concept options for the evolution of Space Station Freedom

Two conceptual evolution configurations for Space Station Freedom, a research and development configuration, and a transportation node configuration are described and analyzed. Results of pertinent analyses of mass properties, attitude control, microgravity, orbit lifetime, and reboost requirements are provided along with a description of these analyses. Also provided are brief descriptions of the elements and systems that comprise these conceptual configurations

The NASA Aerospace Battery Safety Handbook

This handbook has been written for the purpose of acquainting those involved with batteries with the information necessary for the safe handling, storage, and disposal of these energy storage devices. Included in the document is a discussion of the cell and battery design considerations and the role of the components within a cell. The cell and battery hazards are related to user- and/or manufacturer-induced causes. The Johnson Space Center (JSC) Payload Safety Guidelines for battery use in Shuttle applications are also provided. The electrochemical systems are divided into zinc anode and lithium anode primaries, secondary cells, and fuel cells. Each system is briefly described, typical applications are given, advantages and disadvantages are tabulated, and most importantly, safety hazards associated with its use are given

A study of organic Rankine cycle systems with the expansion process performed by twin screw machines

The prediction of the performance of energy systems that recover power from low grade heat is one of the most important requirements for reducing their investment cost and optimising system efficiency. The aim of this work was to study, model and analyse an Organic Rankine cycle (ORC) system using a twin screw expander to generate the power output, with HFC-245fa, as the working fluid. A software package (Power Plant Performance Prediction Program), simulating ORC system performance was therefore prepared for this purpose. Major components were represented by proper units and relations between the system’s constituents defined. The preferred analytical procedure depends on both the system complexity and the requirements of the study. In this case, the whole cycle was simulated in order to obtain a good understanding of its behaviour with the aim of estimating its optimum operating conditions. The procedure adopted was to start from a basic case and then improve it, in a realistic way, in order to evaluate the system potential. Performance indicators, like thermal efficiency, specific net output, total UA and surface of the heat exchangers, as well as the relative cost of the system all need to be taken into account but it is impossible to optimise all of them simultaneously. The design value for these parameters is therefore a matter of choice, or compromise. Efficiencies of ORC systems were calculated based on the assumption that the working fluid entered the expander as wet vapour. For the heat source and sink conditions chosen for this study, the overall cycle efficiency was estimated as approximately 6% using R245fa. This and the power output are highly dependent on the ambient air temperature when using air-cooled condensers. Allowing for a small degree of subcooling at the condenser exit, it is shown that the heat recovery should be maximised

NASA Tech Briefs, November/December 1987

Topics include: NASA TU Services; New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Fabrication Technology; Machinery; Mathematics and Information Sciences; Life Sciences

Ayahuasca characterization, metabolism in humans, and relevance to endogenous N,N-dimethyltryptamines

Ayahuasca denotes an Amazonian psychotropic plant tea obtained from Banisteriopsis caapi, which contains beta-carboline (b-carboline) alkaloids, chiefly harmine, harmaline and tetrahydroharmine. The tea usually incorporates the leaves of Psychotria viridis, which are rich in N,N-dimethyltryptamine (DMT), a psychoactive 5-HT2A agonist. The beta-carbolines reversibly inhibit monoamine-oxidase (MAO), effectively preventing oxidative deamination of the orally inactive DMT and allowing its absorption and access to the central nervous system. Despite increased use of the tea worldwide, easy to perform and validated methods for its characterization do not exist and the metabolism and excretion of DMT and the b-carbolines has not been studied systematically in humans following ayahuasca consumption. Thus, we developed a liquid chromatography–electrospray ionization-tandem mass spectrometry procedure for the simultaneous quantification of the major alkaloid components of ayahuasca, including several known and potential metabolites. The assay was applied to a variety of ayahuasca samples and modified to be applicable to human blood and urine samples before and after consumption of ayahuasca. The major components present in ayahuasca samples were tetrahydroharmine and harmine, followed by DMT and harmaline. The major metabolite of DMT was the corresponding N-oxide, DMT-N-oxide which was found in both blood plasma and urine, although not detectable in ayahuasca samples. Less than 1% of the administered DMT dose was detected in urine or blood plasma, despite the inhibition of monoamine oxidase afforded by the presence of the harmala alkaloids in ayahuasca. The major harmala alkaloid excreted was tetrahydroharmine. The methods developed would be suitable for the study of ayahuasca in human and ethnobotanical research, as well as in forensic examinations of ayahuasca preparations. The characteristics of the methods suggest that their sensitivity, selectivity and reproducibility are adequate for use in further toxicological and clinical research on ayahuasca as well as functioning as an assay to screen biological samples for endogenous hallucinogens. Based on the results of these studies we also present a critical review of 69 published studies reporting the detection in human body fluids of three indole alkaloids that possess differing degrees of psychedelic activity. Suggestions for the future directions of ayahuasca and endogenous psychedelics research are offered