Experiments conducted on combustion at microgravity in the TEXUS-38 sounding rocket

A series of experiments linked together on combustion at microgravity have been conducted in a TEXUS-38 sounding rocket. The experiments were performed with three cylindrical hollow rods of polymethylmethacrylate. Test were carried out in O2-N2 mixtures at rest and at flow velocities ranging from 10 to 30 mm/s. O2-N2 mixture composition changed from 40% oxygen down to pure nitrogen. The sequence of experiments consisted of: 1º.- Measurement of flame temperatures in the non-visible optical range. 2º.- Determination of O2 concentrations at flame extinction at constant flow velocity, obtained by continuously reducing the O2 concentration in the test section. 3º.- Measurement of flame spreading velocities. 4º.- Some information on the influence on flammability of the ignition location and time, and fuel thickness. Main conclusions are: 1º.- Flames in the infrared, non-visible optical range have a substantially lower temperature. 2º.- O2 concentration at flame extinction depends considerably on flow velocity, especially at low velocity levels. Final conclusion is that the flow velocity field of maximum interest is the one in which flow velocities are of the same order of magnitude as typical diffusion velocities. A follow-on program in this subject will be conducted in the US Combustion Module of the International Space Station

GAMES: A new Scenario for Software and Knowledge Reuse

Games are a well-known test bed for testing search algorithms and learning methods, and many authors have presented numerous reasons for the research in this area. Nevertheless, they have not received the attention they deserve as software projects. In this paper, we analyze the applicability of software and knowledge reuse in the games domain. In spite of the need to find a good evaluation function, search algorithms and interface design can be said to be the primary concerns. In addition, we will discuss the current state of the main statistical learning methods and how they can be addressed from a software engineering point of view. So, this paper proposes a reliable environment and adequate tools, necessary in order to achieve high levels of reuse in the games domain

Moduli Spaces of Semistable Sheaves on Singular Genus One Curves

We find some equivalences of the derived category of coherent sheaves on a Gorenstein genus one curve that preserve the (semi)-stability of pure dimensional sheaves. Using them we establish new identifications between certain Simpson moduli spaces of semistable sheaves on the curve. For rank zero, the moduli spaces are symmetric powers of the curve whilst for a fixed positive rank there are only a finite number of non-isomorphic spaces. We prove similar results for the relative semistable moduli spaces on an arbitrary genus one fibration with no conditions either on the base or on the total space. For a cycle $E_N$ of projective lines, we show that the unique degree 0 stable sheaves are the line bundles having degree 0 on every irreducible component and the sheaves $\mathcal{O}(-1)$ supported on one irreducible component. We also prove that the connected component of the moduli space that contains vector bundles of rank $r$ is isomorphic to the $r$-th symmetric product of the rational curve with one node.Comment: 26 pages, 4 figures. Added the structure of the biggest component of the moduli space of sheaves of degree 0 on a cycle of projective lines. Final version; to appear en IMRS (International Mathematics Research Notices 2009

Extension-based argumentation semantics via logic programming semantics with negation as failure

Extension-based argumentation semantics have been shown to be a suitable approach for performing practical reasoning. Since extension-based argumentation semantics were formalized in terms of relationships between atomic arguments, it has been shown that extension-based argumentation semantics (such as the grounded semantics and stable semantics) can be characterized by logic programming semantics with negation as failure. Recently, it has been shown that argumentation semantics such as the preferred semantics and the CF2 semantics can be characterized in terms of logic programming semantics. In this paper, we make a short overview w.r.t. recent results in the close relationship between extension-based semantics and logic programming semantics with negation as failure. We also show that there is enough evidence to believe that the use of declarative approaches based on logic programming semantics with negation as failure is a practical approach for performing practical reasoning following an argumentation reasoning approach.Peer ReviewedPostprint (published version

Planificación de la capacidad hospitalaria en condiciones de incertidumbre

Hospital management must adapt to changes in its environment, where a balance between care and administrative processes predominates, requiring efficient planning. The research aims to propose a procedure for long-term capacity planning under conditions of uncertainty in hospital organizations. A four-stage, quantitative descriptive methodology was designed, including tools such as expert selection, patient flow representation through the different treatment stages, demand forecasting, and capacity calculation. Among the main results, the capacity of the groups related by the diagnosis of the surgical type defined in the service was determined, the operating room was identified as a limiting resource, as well as the percentage of utilization, obtaining 112 % in the operating rooms and 35.58 % of the beds. Among the limitations of the proposed procedure is the level of precision of the capacity calculations (medium-low), typical of long-term planning; however, it enables the heads of hospital government services to propose corrective actions to capacity problems based on a structured methodological procedure that shows how to do the following.La gestión hospitalaria se debe adaptar a los cambios de su entorno, donde predomine un equilibro entre los procesos asistenciales y administrativos, por lo que exige una planeación eficiente. El objetivo de la investigación es proponer un procedimiento para la planeación de la capacidad a largo plazo bajo condiciones de incertidumbre en organizaciones hospitalarias. Se diseñó una metodología estructurada en cuatro etapas, de tipo cuantitativa descriptiva, incluye herramientas como la selección de expertos, representación del flujo de pacientes por las diferentes etapas del tratamiento, previsión de la demanda y cálculo de la capacidad. Entre los principales resultados se determinó la capacidad de los grupos relacionados por el diagnóstico de tipo quirúrgicos definidos en el servicio, se identificó como recurso limitante al salón de operaciones, así como el porcentaje de utilización, obteniéndose un 112 % en los salones y 35,58 % de las camas. Entre las limitaciones del procedimiento propuesto está el nivel de precisión de los cálculos de la capacidad (medio – bajo), propios de la planificación a largo plazo, sin embargo, posibilita a los jefes de servicios de gobierno hospitalario proponer acciones correctivas a problemas de capacidad a partir de un proceder metodológico estructurado que muestra el cómo hacer