34,278 research outputs found

    Computer simulations of iron in magnesium silicate perovskite

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    We use atomistic computer simulation techniques to investigate the site partitioning of iron in (Mg,Fe)SiO_{3} perovskites. Our calculations predict that the most energetically favourable reaction for iron substitution will be a direct exchange of Fe^{2+} for Mg^{2+}. Substitution of Fe into the octahedral site and Si into the 8–12 fold coordinated site, as proposed by Jackson et al. [1987], is predicted to be extremely unlikely

    Generalized Mittag-Leffler Distributions and Processes for Applications in Astrophysics and Time Series Modeling

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    Geometric generalized Mittag-Leffler distributions having the Laplace transform 11+βlog(1+tα),00\frac{1}{1+\beta\log(1+t^\alpha)},00 is introduced and its properties are discussed. Autoregressive processes with Mittag-Leffler and geometric generalized Mittag-Leffler marginal distributions are developed. Haubold and Mathai (2000) derived a closed form representation of the fractional kinetic equation and thermonuclear function in terms of Mittag-Leffler function. Saxena et al (2002, 2004a,b) extended the result and derived the solutions of a number of fractional kinetic equations in terms of generalized Mittag-Leffler functions. These results are useful in explaining various fundamental laws of physics. Here we develop first-order autoregressive time series models and the properties are explored. The results have applications in various areas like astrophysics, space sciences, meteorology, financial modeling and reliability modeling.Comment: 12 pages, LaTe

    Origin of atmospheric aerosols at the Pierre Auger Observatory using backward trajectory of air masses

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    The Pierre Auger Observatory is the largest operating cosmic ray observatory ever built. Calorimetric measurements of extensive air showers induced by cosmic rays are performed with a fluorescence detector. Thus, one of the main challenges is the monitoring of the atmosphere, both in terms of atmospheric state variables and optical properties. To better understand the atmospheric conditions, a study of air mass trajectories above the site is presented. Such a study has been done using an air-modelling program well known in atmospheric sciences. Its validity has been checked using meteorological radiosonde soundings performed at the Pierre Auger Observatory. Finally, aerosol concentration values measured by the Central Laser Facility are compared to backward trajectories.Comment: 4 pages, 6 figures -- ECRS'12 European Cosmic Ray Symposium (July, 3-7, 2012) at Moscow, Russi

    Evaluation of activated sludge treatment and settleability in remediation of edible oil effluent

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    Wastewater discharged from the edible oil industry contains a very concentrated amalgamation of organic and inorganic materials making it a problematic effluent to treat. The aim of this study was to evaluate the activated sludge treatment of edible oil effluent from a sunflower oil processing company in KwaZulu-Natal. A 28 ℓ laboratory-scale modified Ludzack-Ettinger (MLE) activated sludge process was used to treat refinery effluent from the industry. Pre-flocculation of the effluent was necessary to remove the bulk of the fats, oils and greases (FOG) prior to treatment. Routine analyses of chemical oxygen demand (COD), total nitrogen (N), total phosphorus (TP), total suspended solids (TSS), dilute sludge volume index (DSVI) and FOG were conducted in conjunction with microscopic analyses of floc structure, filamentous bacteria and protozoa. An average COD removal of 81% was obtained for the flocculated effluent, at a 15 d sludge age and 24 h hydraulic retention time. However, significantly high TSS values were observed in the treated effluent as a result of sludge-oil aggregation, pin-point floc formation and high numbers of freeswimming bacteria. Microscopic analysis confirmed an absence of filamentous bacteria resulting in poor floc formation, subject to shearing. Periods of soybean oil effluent addition, however, resulted in sludge bulking with DSVI measurements as high as 770 mℓ /g. Fluctuating protozoan populations were also correlated to fluctuating TSS values and were found to be negatively impacted by uncontrolled pre-flocculation. Water SA Vol.29(3) 2003: 245-25

    The Sphaleron Rate in SU(N) Gauge Theory

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    The sphaleron rate is defined as the diffusion constant for topological number NCS = int g^2 F Fdual/32 pi^2. It establishes the rate of equilibration of axial light quark number in QCD and is of interest both in electroweak baryogenesis and possibly in heavy ion collisions. We calculate the weak-coupling behavior of the SU(3) sphaleron rate, as well as making the most sensible extrapolation towards intermediate coupling which we can. We also study the behavior of the sphaleron rate at weak coupling at large Nc.Comment: 18 pages with 3 figure

    Operational Semantics of Process Monitors

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    CSPe is a specification language for runtime monitors that can directly express concurrency in a bottom-up manner that composes the system from simpler, interacting components. It includes constructs to explicitly flag failures to the monitor, which unlike deadlocks and livelocks in conventional process algebras, propagate globally and aborts the whole system's execution. Although CSPe has a trace semantics along with an implementation demonstrating acceptable performance, it lacks an operational semantics. An operational semantics is not only more accessible than trace semantics but also indispensable for ensuring the correctness of the implementation. Furthermore, a process algebra like CSPe admits multiple denotational semantics appropriate for different purposes, and an operational semantics is the basis for justifying such semantics' integrity and relevance. In this paper, we develop an SOS-style operational semantics for CSPe, which properly accounts for explicit failures and will serve as a basis for further study of its properties, its optimization, and its use in runtime verification

    Pengaruh Roa, Der, Eps terhadap Return Saham Perusahaan Food And Beverage Bei

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    Return adalah tujuan dari investor untuk berinvestasi di pasar modal. Investor melakukan berbagai cara agar bisa mendapatkan return yang sesuai diinginkan, dengan melakukan analisis sendiri pada perilaku perdagangan suatu saham, ataupun dengan menggunakan sarana yang sudah disediakan dari analis di pasar modal. Informasi-informasi yang dapat digunakan sebagai tolak ukur tingkat return saham Perusahaan yang diteliti adalah ROA, DER, dan EPS. Perusahaan food and beverage dipilih sebagai populasi yang digunakan dalam penelitian ini yang terdaftar di BEI periode 2008-2012. Teknik purposive sampling digunakan untuk mendapatkan jumlah sampel. Berdasarkan teknik tersebut, 10 Perusahaan diperoleh sebagai sampel. Teknik analisis regresi linier berganda digunakan dalam penelitian ini dengan hasil bahwa semakin tinggi tingkat ROA dan EPS, maka semakin tinggi juga return sahamnya, hanya DER yang memiliki pengaruh negatif dan signifikan terhadap return saham

    Co-simulation setup for online model-assisted control design

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    For reduction of energy intensity of the building sector, effective and parsimonious use of energy resources and climate control systems is a prerequisite. Intelligent Building Energy Management Systems (BEMS) can be key ingredients towards achieving this goal; the incorporation of forecast data into the decision process can help achieve improved performance compared to existing state-of-the-art approaches. In the present paper, the potential of model-based supervisory control design algorithms for automatically designing BEMS is evaluated by performing experiments in a real building. A co-simulation setup is implemented where the thermal simulation model of the building is warmed up using past sensed data and then, given weather and occupancy forecasts, a controller is designed by solving a constrained minimization problem. A stochastic optimization algorithm is used to intelligently search the controller parameter space and identify a controller that minimizes an energy-related cost function, subject to thermal comfort constraints. A middleware solution is deployed in the building to facilitate two-way communication between the building (sensing and actuation) layer and the algorithmic layer

    Role of the mesoamygdaloid dopamine projection in emotional learning

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    Amygdala dopamine is crucially involved in the acquisition of Pavlovian associations, as measured via conditioned approach to the location of the unconditioned stimulus (US). However, learning begins before skeletomotor output, so this study assessed whether amygdala dopamine is also involved in earlier 'emotional' learning. A variant of the conditioned reinforcement (CR) procedure was validated where training was restricted to curtail the development of selective conditioned approach to the US location, and effects of amygdala dopamine manipulations before training or later CR testing assessed. Experiment 1a presented a light paired (CS+ group) or unpaired (CS- group) with a US. There were 1, 2 or 10 sessions, 4 trials per session. Then, the US was removed, and two novel levers presented. One lever (CR+) presented the light, and lever pressing was recorded. Experiment 1b also included a tone stimulus. Experiment 2 applied intra-amygdala R(+) 7-OH-DPAT (10 nmol/1.0 A mu l/side) before two training sessions (Experiment 2a) or a CR session (Experiment 2b). For Experiments 1a and 1b, the CS+ group preferred the CR+ lever across all sessions. Conditioned alcove approach during 1 or 2 training sessions or associated CR tests was low and nonspecific. In Experiment 2a, R(+) 7-OH-DPAT before training greatly diminished lever pressing during a subsequent CR test, preferentially on the CR+ lever. For Experiment 2b, R(+) 7-OH-DPAT infusions before the CR test also reduced lever pressing. Manipulations of amygdala dopamine impact the earliest stage of learning in which emotional reactions may be most prevalent
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