Flooring characteristics of thermo-mechanical densified wood from three hardwood tropical species in costa rica

Densification is one method used to modify low-density woods to make them achieve the hardness required for flooring application. The purpose of this study was to investigate the effect of thermo-mechanical densification with pre-heating in wood of Alnus acuminata, Vochysia ferruginea and Vochysia guatemalensis from, seeking to stabilize and reduce spring-back of the densified wood and evaluate its performance in flooring applications. The results showed that the wood of the three species turned dark. This is because brightness diminished and yellowness and redness increased. Weight loss due to pre-heating was statistically higher in V. ferruginea and V. guatemalensis. The final density and spring-back were statistically similar in the three species. The percentage of densification of A. acuminata and V. guatemalensis were statistically higher than for V. ferruginea and the degree of compression was statistically higher in V. guatemalensis. As for flooring evaluation, the percentage of densification, temperature and time of pre-heating affected the behavior of densified wood flooring. The low percentage of densification and high weight loss in the pre-heating stage caused greater values of wear, wear index, residual deformation, residual indentation for the falling ball indentation test, and more damages in the surface indentation test in wood of V. ferruginea

Service supply chain management : a hierarchical decision modeling approach

A Service Supply Chain (SSC) may be described as a network of service provider facilities (in-house or outsourced), each of which is able to process one or more service tasks on an as needed basis. Two key characteristics of a SSC are (i) the business service is decomposable into several sequential tasks that can be processed by different service providers, and (ii) the primary capacity resource is skilled labor. SSCs are increasingly being developed by companies that experience a high variability of demand for their services (e.g., loan processing, analytical consulting services, emergency repair crews, claims processing, etc.). Typically, the customer wait time penalty is very high, to the extent that if the service is not provided within a certain time, the customer service request will abort. As a result, the service provider needs to maintain sufficient processing capacity to meet peak levels of demand. The primary advantage of a SSC, relative to a traditional dedicated facility, is that the processing capacity (labor) can be economically adjusted (lower hiring and firing costs) to match changes in the current demand level. In this dissertation, a hierarchical framework for modeling the decision structure in SSCs is developed. This framework introduces and defines the key SSC entities: service products, service jobs, service providers, and the parameters for characterizing the demand behavior. As part of the framework two problems are formulated and solved. First, given that Service Supply Chains are intended to be dynamic delivery networks that efficiently respond to demand variations, a strategic problem is which candidate service providers are selected to form the SSC network, and how the service tasks are assigned within the provider network. The problem is formulated and solved as a binary program. Second, a consequent tactical problem is how the workforce level at each service provider is dynamically adjusted (hiring and firing) as the real time demand data comes in the problem is formulated and solved as a linear program that bounds a mixed integer program (MIP). The strategic model takes the demand parameters, the competing providers’ information, and the service and tasks parameters, to select the providers that are going to become part of the SSC and assign tasks to them. A method to quantify cumulative demand variation per seasonal cycle is presented to derive aggregate demand parameters from the forecast. The design objective of the strategic model is to minimize set up cost and projected operational cost. The objective is achieved by simultaneously minimizing capital cost, hiring cost, firing cost, service delay cost, excess capacity cost, labor cost, and quality cost while fulfilling the capacity, tasks assignment, facility installation, and task capability constraints. The tactical model is constrained by the providers and task assignment resulting from the strategic model. It uses a more accurate demand forecast, and minimizes actual operational costs represented by hiring cost, firing cost, backlog cost and labor cost, while fulfilling the production balance, routing, capacity, workforce balance and demand constraints. It is solved in two phases. A relaxed model is solved as an LP and its solution is used for bounding a MIP problem. Finally, the behavior of the two models is studied by performing numerical experiments changing key supply chain parameters such as hiring and firing cost, demand variability, labor cost, and backlog cost

Magnetically-induced ferroelectricity in the (ND4)2[FeCl5(D2O)] molecular compound

The number of magnetoelectric multiferroic materials reported to date is scarce, as magnetic structures that break inversion symmetry and induce an improper ferroelectric polarization typically arise through subtle competition between different magnetic interactions. The (NH4)2[FeCl5(H2O)] compound is a rare case where such improper ferroelectricity has been observed in a molecular material. We have used single crystal and powder neutron diffraction to obtain detailed solutions for the crystal and magnetic structures of (NH4)2[FeCl5(H2O)], from which we determined the mechanism of multiferroicity. From the crystal structure analysis, we observed an order-disorder phase transition related to the ordering of the ammonium counterion. We have determined the magnetic structure below TN, at 2K and zero magnetic field, which corresponds to a cycloidal spin arrangement with magnetic moments contained in the ac-plane, propagating parallel to the c-axis. The observed ferroelectricity can be explained, from the obtained magnetic structure, via the inverse Dzyaloshinskii-Moriya mechanism

Coronagraphic Low Order Wavefront Sensor: Principle and Application to a Phase-Induced Amplitude Coronagraph

High contrast coronagraphic imaging of the immediate surrounding of stars requires exquisite control of low-order wavefront aberrations, such as tip-tilt (pointing) and focus. We propose an accurate, efficient and easy to implement technique to measure such aberrations in coronagraphs which use a focal plane mask to block starlight. The Coronagraphic Low Order Wavefront Sensor (CLOWFS) produces a defocused image of a reflective focal plane ring to measure low order aberrations. Even for small levels of wavefront aberration, the proposed scheme produces large intensity signals which can be easily measured, and therefore does not require highly accurate calibration of either the detector or optical elements. The CLOWFS achieves nearly optimal sensitivity and is immune from non-common path errors. This technique is especially well suited for high performance low inner working angle (IWA) coronagraphs. On phase-induced amplitude apodization (PIAA) type coronagraphs, it can unambiguously recover aberrations which originate from either side of the beam shaping introduced by the PIAA optics. We show that the proposed CLOWFS can measure sub-milliarcsecond telescope pointing errors several orders of magnitude faster than would be possible in the coronagraphic science focal plane alone, and can also accurately calibrate residual coronagraphic leaks due to residual low order aberrations. We have demonstrated 1e-3 lambda/D pointing stability in a laboratory demonstration of the CLOWFS on a PIAA type coronagraph

UV-optical from space

The following subject areas are covered: (1) the science program (star formation and origins of planetary systems; structure and evolution of the interstellar medium; stellar population; the galactic and extragalactic distance scale; nature of galaxy nuclei, AGNs, and QSOs; formation and evolution of galaxies at high redshifts; and cosmology); (2) implementation of the science program; (3) the observatory-class missions (HST; LST - the 6m successor to HST; and next-generation 16m telescope); (4) moderate and small missions (Delta-class Explorers; imaging astrometric interferometer; small Explorers; optics development and demonstrations; and supporting ground-based capabilities); (5) prerequisites - the current science program (Lyman-FUSE; HTS optimization; the near-term science program; data analysis, modeling, and theory funding; and archives); (6) technologies for the next century; and (7) lunar-based telescopes and instruments

Diseño de la Sub Estación Eléctrica para la Planta Industrial Kumho Llantas S.A.

La subestación eléctrica es uno de los elementos más importantes de las grandes empresas que tienen un consumo de energía eléctrico significativo, como nuestra empresa KUMHO LLANTAS S.A. que tiene una gran producción de llantas para todo tipo de aplicaciones, principalmente de la industria minera quienes cuentan con grandes maquinarias que tienen un gran desgaste continuamente, por lo que significan nuestros más grandes clientes en el Perú. Las características técnicas de las llantas de nuestra empresa KUMHO LLANTAS S.A. representan una gran ventaja con respecto a la competencia, por lo que nuestra producción está garantizada, por lo que la cantidad de producción de las llantas requiere un gran consumo de energía eléctrica, y por ello se necesita la construcción de una subestación eléctrica que abastezca dicho consumo. Por lo expuesto y en función a las necesidades de la gran industria y la minería peruana, se implementará una ampliación al taller de reparaciones de neumáticos gigantes (Servi Llantas), en conjunto entre la transnacional Michelin y Khumo llantas S.A.; único taller en el Perú homologado por Michelin; dicha ampliación servirá para poder mejorar y crear nuevos procesos para la reparación y el mantenimiento de neumáticos gigantes, para lo cual será necesaria la compra de nuevos equipos tales como: - Hornos de Inducción - Cámaras de secado - Área de soldadura especializada - Banco de compresores - Herramientas especializadas, entre otras. Considerando las cargas eléctricas existentes y las cargas eléctricas futuras que se han detallado para la ampliación correspondiente, es que se hace necesario comprar la energía eléctrica en Media Tensión ya que la Máxima Demanda eléctrica así lo requiere y para su debida utilización se necesitara la implementación de una subestación eléctrica que permita disminuir el nivel de tensión a valores adecuados para su uso. RESUMEN CARGA INSTALADA Descripción dela carga Potencia kW Banco de compresores 33,6 Área de soldadura 18 Hornos de inducción 200 Cámara de secado 30 Circuitos Planta 1 15 Circuitos Planta 2 10 Sistemas de Computo 8 Otros 5 TOTAL 319,6 Tenemos una potencia instalada de 319.6 KW a la que le agregaremos por motivos de aumento de carga y seguridad el 25 %, obteniendo así una Máxima demanda de 399,5 KW, diseñando por tal motivo una SE de 400 KVA, que es un valor comercial del transformador eléctrico. Palabras claves: Sub estación eléctrica – Planta Industrial

Impact micro-positioning actuator

An impact micro-positioning actuator. In one aspect of the invention, a threaded shaft is threadably received in a nut and the nut is impacted by an impacting device, causing the nut first to rotate relative to the shaft by slipping as a result of shaft inertia and subsequently to stick to the shaft as a result of the frictional force therebetween. The nut is returned to its initial position by a return force provided by a return mechanism after impact. The micro-positioning actuator is further improved by controlling at least one and preferably all of the following: the friction, the impact provided by the impacting device, the return force provided by the return mechanism, and the inertia of the shaft. In another aspect of the invention, a threaded shaft is threadably received in a nut and the shaft is impacted by an impacting device, causing the shaft to rotate relative to the nut

Validación del Münchner Alkoholismus Test Subjektiv para el diagnóstico de alcoholismo en población adulta

ResumenObjetivoValidar la parte subjetiva del cuestionario MALT (Münchner Alkoholismus Test) para el diagnóstico de alcoholismo en población adulta.DiseñoEstudio descriptivo de validación de un instrumento diagnóstico.EmplazamientoDos centros de atención primaria, un centro de drogodependencias y un centro de atención a alcohólicos, ubicados en la provincia de Córdoba, España.ParticipantesSeiscientos catorce pacientes con edades de entre 18 y 80 años.Mediciones principalesMediante entrevista personal se realizaron los cuestionarios MALT, AUDIT (Alcohol Use Disorders Identification Test) y el SCAN (Schedules for clinical assessment in Neuropsychiatry). Se analizó la fiabilidad interna, la reproducibilidad, la validez criterial (patrón de referencia: criterios del Manual Diagnóstico y Estadístico de los Trastornos Mentales IV [DSM-IV]) y la validez convergente.ResultadosLa edad media de la población fue de 43 años (desviación estándar de 1,43). El 17,4% presentó síndrome de dependencia alcohólica. Los coeficientes kappa de los ítems del test oscilaban entre 0,568 y 0,969. El alfa de Cronbach del MALT completo fue de 0,919; el alfa de Cronbach del MALT subjetivo fue de 0,939, y el alfa de Cronbach del MALT objetivo fue de 0,737. El área bajo la curva de eficacia diagnóstica para el MALT-S fue de 0,946 y para el MALT completo fue de 0,953. Para un punto de corte de 4, la sensibilidad del MALT-S fue del 92,6% y la especificidad fue del 90,8%. El coeficiente de correlación del MALT-S y del AUDIT fue de 0,86 (p<0,001).ConclusionesEl MALT subjetivo es un cuestionario tan válido y fiable como el MALT completo, por lo que puede ser utilizado aisladamente para la detección y el diagnóstico de alcoholismo.AbstractObjectiveTo validate the subjective part of the MALT questionnaire (MALT-S) for the detection of alcoholism among the adult population.DesignA descriptive study on the validation of a diagnostic tool.SettingTwo primary health care centres, a centre for drug addicts and a centre for alcoholics in Cordoba (Spain).Participants614 patients, between 18 and 80 years.MeasurementsThrough personal interviews the MALT, AUDIT and SCAN questionnaires were given. The internal reliability, stability and both the criterion and convergent validity were analysed.ResultsThe mean age of the population’ was 43±1.43 (SD) years and 17.4% of them showed Alcohol Dependence Syndrome. The Kappa coefficients of the test items ranged from 0.568 to 0.969. The Cronbach alpha of the complete MALT was 0.919, of the MALT-S, 0.939 and of the MALT-O, 0.737. The area under the ROC curve of the MALT-S was 0.946 and that of the complete MALT was 0.953. For a cut-off point of four, the sensitivity of the MALT-S is 92.7% while its specificity was 90.9%. The correlation coefficient of the MALT-S and AUDIT was 0.86 (P<0.001).ConclusionsThe MALT-S questionnaire is as valid and reliable as the complete MALT; therefore, it can be used on its own for the diagnosis of alcoholism