Uplift Quadratic Program in Irish Electricity Price Setting

Bord Gis required a deeper insight into the dynamics of Uplift prices. The aim of the group was to apply a variety of analytical tools to the problem in order to satisfy Bord Gis requirements. The group conducted a KKT Optimality Analysis of the quadratic program used to determine the Uplift prices, performed statistical analysis to identify the binding constraints and their sensitives to the Uplift prices, simulated a synthetic stochastic process that is consistent with the Uplift pricing series and investigated alternative objective functions for the quadratic program

Prospects for an orbital determination and capture cell experiment

A dust experiment which combines measurements of the elemental and isotopic composition of individual particles with orbital information would contribute fundamental, new scientific information on the sources contributing to the micrometeoroid population. The general boundary conditions for such a system are: (1) it must be capable of measuring velocities in the range of 10 km/sec to 100 km/sec with several percent accuracy; (2) it must collect particles in such a way that the debris atoms are locally concentrated so that precise isotopic measurements are possible; (3) it should collect particles over a wide range of sizes starting with a lower limit of 10 microns; (4) it should incorporate materials that will not compromise the isotopic measurements; and (5) it should be large enough to obtain statistically meaningful results within a reasonable exposure time. Techniques which may satisfy these conditions are described

A Maximum Entropy Method of Obtaining Thermodynamic Properties from Quantum Monte Carlo Simulations

We describe a novel method to obtain thermodynamic properties of quantum systems using Baysian Inference -- Maximum Entropy techniques. The method is applicable to energy values sampled at a discrete set of temperatures from Quantum Monte Carlo Simulations. The internal energy and the specific heat of the system are easily obtained as are errorbars on these quantities. The entropy and the free energy are also obtainable. No assumptions as to the specific functional form of the energy are made. The use of a priori information, such as a sum rule on the entropy, is built into the method. As a non-trivial example of the method, we obtain the specific heat of the three-dimensional Periodic Anderson Model.Comment: 8 pages, 3 figure

Interfacial properties of most monofluorinated bile acids deviate markedly from the natural congeners: studies with the Langmuir-Pockels surface balance

We characterized the air-water interfacial properties of four monofluorinated bile acids alone and in binary mixtures with a common lecithin, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), using an automated Langmuir-Pockels surface balance. We compared 7alpha-fluoromurocholic acid (FMCA), 7alpha-fluorohyodeoxycholic acid (FHDCA), 6alpha-fluoroursodeoxycholic acid (FUDCA), and 6alpha-fluorochenodeoxycholic acid (FCDCA) with their natural dihydroxy homologs, murocholic acid (MCA), hyodeoxycholic acid (HDCA), ursodeoxycholic acid (UDCA), and chenodeoxycholic acid (CDCA). For further comparison, two trihydroxy bile acids, 3alpha,6beta,7alpha-trihydroxycholanoic acid [alpha-muricholic acid (alpha-MCA)] and 3alpha,6alpha,7beta-trihydroxycholanoic acid [omega-muricholic acid (omega-MCA)], with isologous OH polar functions to FMCA and FUDCA were also studied. Pressure-area isotherms of MCA, HDCA, UDCA, CDCA, and FMCA displayed sharp collapse points. In contrast, FHDCA, FUDCA, and FCDCA formed monolayers that were less stable than the trihydroxy bile acids, displaying second-order phase transitions in their isotherms. All natural and fluorinated bile acids condensed mixed monolayers with POPC, with maximal effects at molar bile acid concentrations between 30 and 50 mol%. Examination of molecular models revealed that the 7alpha-F atom of the interfacially stable FMCA projects away from the 6beta-OH function, resulting in minimal steric interactions, whereas in FHDCA, FUDCA, and FCDCA, close vicinal interactions between OH and F polar functions result in progressive bulk solubility upon monolayer compression. These results provide a framework for designing F-modified bile acids to mimic or diverge from the natural compounds in vivo

Current-driven microwave oscillations in current perpendicular-to-plane spin-valve nanopillars

We study the current and temperature dependences of the microwave voltage emission of spin-valve nanopillars subjected to an in-plane magnetic field and a perpendicular-to-plane current. Despite the complex multilayer geometry, clear microwave emission is shown to be possible and spectral lines as narrow as 3.8 MHz (at 150 K) are observed.Comment: To appear in Applied Physics Letter

Space Transportation System Availability Requirement and Its Influencing Attributes Relationships

It is important that engineering and management accept the need for an availability requirement that is derived with its influencing attributes. It is the intent of this paper to provide the visibility of relationships of these major attribute drivers (variables) to each other and the resultant system inherent availability. Also important to provide bounds of the variables providing engineering the insight required to control the system's engineering solution, e.g., these influencing attributes become design requirements also. These variables will drive the need to provide integration of similar discipline functions or technology selection to allow control of the total parts count. The relationship of selecting a reliability requirement will place a constraint on parts count to achieve a given availability requirement or if allowed to increase the parts count will drive the system reliability requirement higher. They also provide the understanding for the relationship of mean repair time (or mean down time) to maintainability, e.g., accessibility for repair, and both the mean time between failure, e.g., reliability of hardware and availability. The concerns and importance of achieving a strong availability requirement is driven by the need for affordability, the choice of using the two launch solution for the single space application, or the need to control the spare parts count needed to support the long stay in either orbit or on the surface of the moon. Understanding the requirements before starting the architectural design concept will avoid considerable time and money required to iterate the design to meet the redesign and assessment process required to achieve the results required of the customer's space transportation system. In fact the impact to the schedule to being able to deliver the system that meets the customer's needs, goals, and objectives may cause the customer to compromise his desired operational goal and objectives resulting in considerable increased life cycle cost of the fielded space transportation system

Synthesis, characterization of a new carbonylated zirconium metallocene using a dichloro-zirconocene derived from partially alkylated s-indacene

Indexación: ScieloThis work describes the synthesis and characterization of new organometallic species, an unprecedented mononuclear zirconium complex bearing a tetraalkylated s-indacene ligand, and secondly, its respective dicarbonyl complex obtained by reduction with Mg/HgCl2. Theoretical calculations of these two compounds were carried out to gain further understanding of these novel molecular systems.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072009000300014&lng=es&nrm=is