36,729 research outputs found

    Forecasting Sales of Slow and Fast Moving Inventories.

    Get PDF
    Adaptations of simple exponential smoothing are presented that aim to unify the task of forecasting demand for both slow and fast moving inventories. A feature of the adaptations is that they are designed to ensure that the resulting prediction distributions have only a nonnegative domain. A parametric bootstrap approach is proposed for generating empirical approximations for the so-called lead-time demand distribution, something required for inventory control calculations. The proposed methods are illustrated and their performance compared on real demand data for car parts.demand forecasting, inventory control, simulation, parametric bootstrapping, time series analysis.

    Space processing on Skylab and ASTP

    Get PDF
    The Skylab and Apollo Soyuz Test Project (ASTP) missions provided the opportunity the influence of micro-gravity on the processing of various materials. The results of physical and engineering experiments in metallurgy, fluids handling and crystal growth on two space missions are discussed. The majority of the experiments concern the solidification of alloys, semiconductors, and composite materials or basic liquid-liquid and solid-liquid interactions necessary to understand complex processing. Potential advantages of space processing to several materials disciplines are identified

    Electrophoresis device

    Get PDF
    A device for separating cellular particles of a sample substance into fractionated streams of different cellular species includes a casing having a distribution chamber, a separation chamber, and a collection chamber. The electrode chambers are separated from the separation chamber interior by means of passages such that flow variations and membrane variations around the slotted portion of the electrode chamber do not enduce flow perturbations into the laminar buffer curtain flowing in the separation chamber. The cellular particles of the sample are separated under the influence of the electrical field and the separation chamber into streams of different cellular species. The streams of separated cells enter a partition array in the collection chamber where they are fractionated and collected

    Vehicle for civil helicopter ride quality research

    Get PDF
    A research aircraft for investigating the factors involved in civil helicopter operations was developed for NASA Langley Research Center. The aircraft is a reconfigured 17000 kg (36000 lb) military transport helicopter. The basic aircraft was reconfigured with advanced acoustic treatment, air-conditioning, and a 16-seat airline cabin. During the spring of 1975, the aircraft was flight tested to measure interior environment characteristics - noise and vibration - and was flown on 60 subjective flight missions with over 600 different subjects. Data flights established noise levels somewhat higher than expected, with a pure tone at 1400 Hz and vertical vibration levels between 0.07g and 0.17g. The noise and vibration levels were documented during subjective flight evaluations as being the primary source of discomfort. The aircraft will be utilized to document in detail the impact of various noise and vibration levels on passenger comfort during typical short-haul missions

    Method of crystallization

    Get PDF
    A method is described for refining or growing bulk single crystals in an environment substantially free of gravity. The base material is suspended, positioned, and shaped as a containerless melt by wetting forces. Because no crucible is required, high temperature refractory materials can be processed

    Experimental study of the impedance of a short dipole in a plasma for parallel and perpendicular orientation with respect to the dc magnetic field

    Get PDF
    Impedance measurements on small dipole immersed in anisotropic plasma with external electric fiel
    • …
    corecore