Brayton heat exchanger unit development program (alternate design)

A Brayton Heat Exchanger Unit Alternate Design (BHXU-Alternate) consisting of a recuperator, a heat sink heat exchanger, and a gas ducting system, was designed and fabricated. The design was formulated to provide a high performance unit suitable for use in a long-life Brayton-cycle powerplant. Emphasis was on double containment against external leakage and leakage of the organic coolant into the gas stream. A parametric analysis and design study was performed to establish the optimum component configurations to achieve low weight and size and high reliability, while meeting the requirements of high effectiveness and low pressure drop. Layout studies and detailed mechanical and structural design were performed to obtain a flight-type packaging arrangement, including the close-coupled integration of the BHXU-Alternate with the Brayton Rotating Unit (BRU)

The Peak Brightness and Spatial Distribution of AGB Stars Near the Nucleus of M32

The bright stellar content near the center of the Local Group elliptical galaxy M32 is investigated with 0.12 arcsec FWHM H and K images obtained with the Gemini Mauna Kea telescope. Stars with K = 15.5, which are likely evolving near the tip of the asymptotic giant branch (AGB), are resolved to within 2 arcsec of the nucleus, and it is concluded that the peak stellar brightness near the center of M32 is similar to that in the outer regions of the galaxy. Moreover, the projected density of bright AGB stars follows the visible light profile to within 2 arcsec of the nucleus, indicating that the brightest stars are well mixed throughout the galaxy. Thus, there is no evidence for an age gradient, and the radial variations in spectroscopic indices and ultraviolet colors that have been detected previously must be due to metallicity and/or some other parameter. We suggest that either the bright AGB stars formed as part of a highly uniform and coherent galaxy-wide episode of star formation, or they originated in a separate system that merged with M32.Comment: 9 pages of text, 3 figures. ApJ (Letters) in pres

Neural NILM: Deep Neural Networks Applied to Energy Disaggregation

Energy disaggregation estimates appliance-by-appliance electricity consumption from a single meter that measures the whole home's electricity demand. Recently, deep neural networks have driven remarkable improvements in classification performance in neighbouring machine learning fields such as image classification and automatic speech recognition. In this paper, we adapt three deep neural network architectures to energy disaggregation: 1) a form of recurrent neural network called `long short-term memory' (LSTM); 2) denoising autoencoders; and 3) a network which regresses the start time, end time and average power demand of each appliance activation. We use seven metrics to test the performance of these algorithms on real aggregate power data from five appliances. Tests are performed against a house not seen during training and against houses seen during training. We find that all three neural nets achieve better F1 scores (averaged over all five appliances) than either combinatorial optimisation or factorial hidden Markov models and that our neural net algorithms generalise well to an unseen house.Comment: To appear in ACM BuildSys'15, November 4--5, 2015, Seou

The effect of active video gaming on children\u27s physical activity, behavior preferences and body composition

Active video game interventions typically provide children a single game that may become unappealing. A peripheral device (jOG) encourages step-powered gaming on multiple games. This trial evaluated the effect of jOG on children’s objectively measured PA, body fat and self-reported behaviors. 42 of 58 eligible children (8–10 y) randomly assigned to an intervention (jOG) or control (CON) completed the trial. Intervention children received two jOG devices for home use. Analyses of covariance compared the intervention effect at 6 and 12 weeks from baseline. No differences were found between groups for counts per minute (CPM; primary outcome) at 6 and 12 weeks (p &gt; .05). Active video gaming increased (adjusted change 0.95 (95% CI 0.25, 1.65) h·d−1, p&lt;.01) and sedentary video gaming decreased (-0.34 (-1.24, 0.56) h·d−1, p &gt; .05) at 6 weeks relative to CON. No body fat changes were observed between groups. Targeted changes in video game use did not positively affect PA. Larger trials are needed to verify the impact of active video games on children’s PA and health.</jats:p

Computational Study Of Molecular Hydrogen In Zeolite Na-A. II. Density Of Rotational States And Inelastic Neutron Scattering Spectra

Part I of this series [J. Chem. Phys. 111, 7599 (1999)] describes a simulation of H(2) adsorbed within zeolite Na-A in which a block Lanczos procedure is used to generate the first several (9) rotational eigenstates of H(2), modeled as a rigid rotor, and equilibrated at a given temperature via Monte Carlo sampling. Here, we show that rotational states are strongly perturbed by the electrostatic fields in the solid. Wave functions and densities of rotational energy states are presented. Simulated neutron spectra are compared with inelastic neutron scattering data. Comparisons are made with IR spectra in which rotational levels may appear due to rovibrational coupling. (C) 2001 American Institute of Physics

Computational Study Of Molecular Hydrogen In Zeolite Na-A. I. Potential Energy Surfaces And Thermodynamic Separation Factors For Ortho And Para Hydrogen

We simulate H-2 adsorbed within zeolite Na-A. We use a block Lanczos procedure to generate the first several (9) rotational eigenstates of the molecule, which is modeled as a rigid, quantum rotor with an anisotropic polarizability and quadrupole moment. The rotor interacts with Na cations and O anions; interaction parameters are chosen semiempirically and the truncation of electrostatic fields is handled with a switching function. A Monte Carlo proceedure is used to sample a set of states based on the canonical distribution. Potential energy surfaces, favorable adsorbtion sites, and distributions of barriers to rotation are analyzed. Separation factors for ortho-parahydrogen are calculated; at low temperatures, these are controlled by the ease of rotational tunneling through barriers. (C) 1999 American Institute of Physics

Effect of periodic parametric excitation on an ensemble of force-coupled self-oscillators

We report the synchronization behavior in a one-dimensional chain of identical limit cycle oscillators coupled to a mass-spring load via a force relation. We consider the effect of periodic parametric modulation on the final synchronization states of the system. Two types of external parametric excitations are investigated numerically: periodic modulation of the stiffness of the inertial oscillator and periodic excitation of the frequency of the self-oscillatory element. We show that the synchronization scenarios are ruled not only by the choice of parameters of the excitation force but depend on the initial collective state in the ensemble. We give detailed analysis of entrainment behavior for initially homogeneous and inhomogeneous states. Among other results, we describe a regime of partial synchronization. This regime is characterized by the frequency of collective oscillation being entrained to the stimulation frequency but different from the average individual oscillators frequency.Comment: Comments and suggestions are welcom

Andean Land Use And Biodiversity: Humanized Landscapes In A Time Of Change

Some landscapes Cannot be understood without reference., to the kinds. degrees, kinds, degrees, and history of human-caused modifications to the Earth's surface. The tropical latitudes of the Andes represent one such place, with agricultural land-use systems appearing in the Early Holocene. Current land use includes both intensive and extensive grazing and crop- or tree-based agricultural systems found across virtually the, entire range of possible elevations and humidity regimes. Biodiversity found in or adjacent to such humanized landscapes will have been altered in abundance. composition, and distribution in relation to the resiliency of the native Species to harvest, hold cover modifications, and other deliberate or inadvertent human land uses. In addition, the geometries of land cover, resulting flout difference among the shapes, sizes, connectivities, and physical structures of the patches, corridors, and matrices that compose landscape mosaics, will constrain biodiversity, often in predictable ways. This article proposes a conceptual model that alter ins that the Continued persistence of native species may depend as much oil the shifting Of Andean landscape mosaics as on species characteristics, themselves. Furthermore, mountains such as the Andes display long gradients of environmental Conditions that after in relation to latitude, soil moisture, aspect, and elevation. Global environmental change will shift these, especially temperature and humidity regimes along elevational gradients, causing Changes outside the historical range of variation for some species. Both land-use systems and Conservation efforts will need to respond spatially to these shifts in the future, at both landscape and regional scales.Geography and the Environmen