1,749 research outputs found

    Exiled: From the Killing Fields of Cambodia to California and Back

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    Katya Cengel, freelance writer and Journalism Lecturer at Cal Poly, discusses her new book, Exiled: From the Killing Fields of Cambodia to California and Back. Ms. Cengel has published in many venues, including the New York Times Magazine, the Washington Post, and the Wall Street Journal. Dr. Margaret Bodemer, a specialist in Southeast Asia who teaches both Asian and American history at Cal Poly, serves as Ms. Cengel’s conversational partner.https://digitalcommons.calpoly.edu/convocpauth/1010/thumbnail.jp

    Nonequilibrium entropy production for open quantum systems

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    We consider open quantum systems weakly coupled to a heat reservoir and driven by arbitrary time-dependent parameters. We derive exact microscopic expressions for the nonequilibrium entropy production and entropy production rate, valid arbitrarily far from equilibrium. By using the two-point energy measurement statistics for system and reservoir, we further obtain a quantum generalization of the integrated fluctuation theorem put forward by Seifert [PRL 95, 040602 (2005)].Comment: 4 pages, 1 figur

    Dimensional analysis and Rutherford Scattering

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    Dimensional analysis, and in particular the Buckingham Π\Pi theorem is widely used in fluid mechanics. In this article we obtain an expression for the impact parameter from Buckingham's theorem and we compare our result with Rutherford's original discovery found in the early twentieth century

    Limitations in Predicting the Space Radiation Health Risk for Exploration Astronauts

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    Despite years of research, understanding of the space radiation environment and the risk it poses to long-duration astronauts remains limited. There is a disparity between research results and observed empirical effects seen in human astronaut crews, likely due to the numerous factors that limit terrestrial simulation of the complex space environment and extrapolation of human clinical consequences from varied animal models. Given the intended future of human spaceflight, with efforts now to rapidly expand capabilities for human missions to the moon and Mars, there is a pressing need to improve upon the understanding of the space radiation risk, predict likely clinical outcomes of interplanetary radiation exposure, and develop appropriate and effective mitigation strategies for future missions. To achieve this goal, the space radiation and aerospace community must recognize the historical limitations of radiation research and how such limitations could be addressed in future research endeavors. We have sought to highlight the numerous factors that limit understanding of the risk of space radiation for human crews and to identify ways in which these limitations could be addressed for improved understanding and appropriate risk posture regarding future human spaceflight.Comment: Accepted for publication by Nature Microgravity (2018

    Second law analysis of a conventional steam power plant

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    A numerical investigation of exergy destroyed by operation of a conventional steam power plant is computed via an exergy cascade. An order of magnitude analysis shows that exergy destruction is dominated by combustion and heat transfer across temperature differences inside the boiler, and conversion of energy entering the turbine/generator sets from thermal to electrical. Combustion and heat transfer inside the boiler accounts for 53.83 percent of the total exergy destruction. Converting thermal energy into electrical energy is responsible for 41.34 percent of the total exergy destruction. Heat transfer across the condenser accounts for 2.89 percent of the total exergy destruction. Fluid flow with friction is responsible for 0.50 percent of the total exergy destruction. The boiler feed pump turbine accounts for 0.25 percent of the total exergy destruction. Fluid flow mixing is responsible for 0.23 percent of the total exergy destruction. Other equipment including gland steam condenser, drain cooler, deaerator and heat exchangers are, in the aggregate, responsible for less than one percent of the total exergy destruction. An energy analysis is also given for comparison of exergy cascade to energy cascade. Efficiencies based on both the first law and second law of thermodynamics are calculated for a number of components and for the plant. The results show that high first law efficiency does not mean high second law efficiency. Therefore, the second law analysis has been proven to be a more powerful tool in pinpointing real losses. The procedure used to determine total exergy destruction and second law efficiency can be used in a conceptual design and parametric study to evaluate the performance of other steam power plants and other thermal systems

    Parametric analysis on the performance of a revolutionary rotary Ericsson heat pump/engine

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    © The Author(s) 2018. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.A revolutionary mechanical heat pump/engine system utilizing the Ericsson thermodynamic cycle has been proposed to provide efficient and environmentally friendly cooling. Computer simulation models have been developed to simulate the rotor positions. Further modelling has been conducted to predict the torque and power of the rotary Ericsson heat pump (REHP). Parametric and optimization study has been conducted to evaluate the factors affecting the mechanical and thermal performance of the conceptually designed REHP. It has been found that the rotor size, compression ratio and base pressure are the factors determining the maximum torque and power of the MG.Peer reviewedFinal Published versio

    Insulin Receptor Substrate-1 Serine Phosphorylation by a Novel Phosphatidylinositol-3'-Kinase-Associated Serine Kinase Regulates Insulin and Interferon Receptor Signaling

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    139 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.The data in this thesis demonstrate that phosphatidylinositol 3 '-kinase (PI 3- kinase) associates with a novel serine kinase that can phosphorylate IRS-1 and reduce its ability to act as a substrate for insulin and interferon alpha (IFNalpha) receptors. PI 3-kinase is shown to associate with a wortmannin insensitive 76 kDa serine phosphoprotein (pp76) distinct from the p85 subunit of PI 3-kinase. pp76 is phosphorylated by an okadaic acid sensitive, PI 3-kinase associated serine kinase (PAS kinase) with biochemical properties that distinguish it from the intrinsic serine kinase activity of PI 3-kinase and evidence suggests that PAS kinase may be pp76. PAS kinase associates with the p85 subunit of PI 3-kinase through src homology 2 (SH2) domain interactions and can serine phosphorylate IRS-1 after insulin stimulation. More importantly, PAS kinase mediated IRS-1 serine phosphorylation reduced subsequent tyrosine phosphorylation of IRS-1 by insulin receptors (IRs). Finally, under hyperinsulinernic conditions, IRS-1 serine phosphorylation by PAS kinase can reduce IFNalpha mediated IRS-1 tyrosine phosphorylation. Taken together, these data show that PAS kinase is an IRS-1 serine kinase and that PAS kinase may counter-regulate insulin and cytokine signaling.Ope

    Single ion heat engine with maximum efficiency at maximum power

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    We propose an experimental scheme to realize a nano heat engine with a single ion. An Otto cycle may be implemented by confining the ion in a linear Paul trap with tapered geometry and coupling it to engineered laser reservoirs. The quantum efficiency at maximum power is analytically determined in various regimes. Moreover, Monte Carlo simulations of the engine are performed that demonstrate its feasibility and its ability to operate at maximum efficiency of 30% under realistic conditions.Comment: 5 pages, 3 figure

    A combined study of heat and mass transfer in an infant incubator with an overhead screen

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    The main objective of this study is to investigate the major physical processes taking place inside an infant incubator, before and after modifications have been made to its interior chamber. The modification involves the addition of an overhead screen to decrease radiation heat losses from the infant placed inside the incubator. The present study investigates the effect of these modifications on the convective heat flux from the infant’s body to the surrounding environment inside the incubator. A combined analysis of airflow and heat transfer due to conduction, convection, radiation and evaporation has been performed, in order to calculate the temperature and velocity fields inside the incubator before and after the design modification. Due to the geometrical complexity of the model, Computer-Aided Design (CAD) applications were used to generate a computer-based model. All numerical calculations have been performed using the commercial Computational Fluid Dynamics (CFD) package FLUENT, together with in-house routines used for managing purposes and User-Defined Functions (UDFs) which extend the basic solver capabilities. Numerical calculations have been performed for three different air inlet temperatures: 32, 34 and 36ºC. The study shows a decrease of the radiative and convective heat losses when the overhead screen is present. The results obtained were numerically verified as well as compared with results available in the literature from investigations of dry heat losses from infant manikins

    Tests of prototype PCM 'sails' for office cooling

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    This is the post-print version of the final paper published in Applied Thermal Engineering. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2010 Elsevier B.V.PCM modules, constructed from a paraffin/LDPE composite, were tested in an occupied London office, in summer. Design variations tested the effect on heat transfer of a black paint or aluminium surface, the effect of different phase transition zones and the effect of discharging heat inside or outside. The modules’ temperatures were monitored along with airflow rate, air temperature and globe temperature. Their small size meant any effect on room temperature was negligible. Using DSC measurements of the PCMs’ thermophysical properties, in conjunction with the environmental measurements, a semi-empirical model of the modules was constructed in FLUENT using an enthalpy-porosity formulation to model phase change. Good validation was obtained for all modules using the temperature measurements with notable divergence when maximum liquid fraction was reached. The model was validated by the temperature measurements and used to generate mean liquid fraction and surface heat transfer rate profiles for performance comparisons. The broad phase transition zones of the PCMs results in wasted latent heat capacity. Black modules transfer heat and exhaust latent storage capacity significantly quicker than aluminium modules, due to radiant exchange. Discharging heat outside leads to an increase in thermal storage capacity and a higher rate of heat absorption.Buro Happold Engineers and the EPSRC
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