4,466 research outputs found

    Artificial Neural Network Based Prediction of Optimal Pseudo-Damping and Meta-Damping in Oscillatory Fractional Order Dynamical Systems

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    This is the author accepted manuscript. The final version is available from IEEE via the link in this record.This paper investigates typical behaviors like damped oscillations in fractional order (FO) dynamical systems. Such response occurs due to the presence of, what is conceived as, pseudo-damping and meta-damping in some special class of FO systems. Here, approximation of such damped oscillation in FO systems with the conventional notion of integer order damping and time constant has been carried out using Genetic Algorithm (GA). Next, a multilayer feed-forward Artificial Neural Network (ANN) has been trained using the GA based results to predict the optimal pseudo and meta-damping from knowledge of the maximum order or number of terms in the FO dynamical system

    Three-coordinate iron(II) expanded ring N-heterocyclic carbene complexes

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    A sterically demanding seven-membered expanded ring N-heterocyclic carbene (NHC) ligand allows access to rare examples of three-coordinate iron(II)-NHC complexes incorporating only halide coligands of the general formula [Fe(NHC)X 2 ] (NHC = 7-DiPP; X = Br (1) Cl (2)). Reducing the steric influence of the ancillary NHC ligand through modulation of the N-aryl substituents leads to either four- or three-coordinate complexes of the general formula [Fe(NHC)Br 2 (THF)] (3) or [Fe(NHC)Br 2 ] (4) (NHC = 7-Mes), dependent upon the solvent of recrystallization. The further reduction of NHC steric influence results in four-coordinate geometries at iron in the form of the dimeric species [Fe(NHC)Br(μ-Br)] 2 (5) or [Fe(NHC)Br 2 (THF)] (6) (NHC = SDiPP), again dependent upon the solvent of recrystallization. Compounds 1-6 have been analyzed by 1 H NMR spectroscopy, X-ray crystallography, elemental microanalysis, Mössbauer spectroscopy (for 1 and 3-5), and Evans method magnetic susceptibility. In addition to these measurements the three-coordinate species 1 and 4 have been further analyzed by SQUID magnetometry and CASSCF calculations, which show significant magnetic anisotropy that is extremely sensitive to the coordination geometry

    What can we say about seed fields for galactic dynamos?

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    We demonstrate that a quasi-uniform cosmological seed field is a much less suitable seed for a galactic dynamo than has often been believed. The age of the Universe is insufficient for a conventional galactic dynamo to generate a contemporary galactic magnetic field starting from such a seed, accepting conventional estimates for physical quantities. We discuss modifications to the scenario for the evolution of galactic magnetic fields implied by this result. We also consider briefly the implications of a dynamo number that is significantly larger than that given by conventional estimates

    Real world and tropical cyclone world. Part I: high-resolution climate model verification

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    Recent global climate models with sufficient resolution and physics offer a promising approach for simulating real-world tropical cyclone (TC) statistics and their changing relationship with climate. In the first part of this study, we examine the performance of a high-resolution (;40-km horizontal grid) global climate model, the atmospheric component of the Australian Community Climate and Earth System Simulator (ACCESS) based on the Met Office Unified Model (UM8.5) Global Atmosphere (GA6.0). The atmospheric model is forced with observed sea surface temperature, and 20 years of integrations (1990–2009) are analyzed for evaluating the simulated TC statistics compared with observations. The model reproduces the observed climatology, geographical distribution, and interhemispheric asymmetry of global TC formation rates reasonably well. The annual cycle of regional TC formation rates over most basins is also well captured. However, there are some regional biases in the geographical distribution of TC formation rates. To identify the sources of these biases, a suite of model-simulated large-scale climate conditions that critically modulate TC formation rates are further evaluated, including the assessment of a multivariate genesis potential index. Results indicate that the model TC genesis biases correspond well to the inherent biases in the simulated large-scale climatic states, although the relative effects on TC genesis of some variables differs between basins. This highlights the model’s mean-state dependency in simulating accurate TC formation rates

    Process Standardization for the Manufacture of Shrikhand Spread

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    Purpose: Shrikhand Spread, a unique sweetened fermented Indian milk product is made by separation of whey from dahi, the Indian counterpart of Western yoghurt, followed by addition of sugar. Production of dahi employing traditional method involved undefined mixed starter cultures, uncontrolled fermentation and longer production time resulting in wide variation in its chemical and microbiological qualities. In order to cater to a product with desirable properties like lower post-acidification, higher flavour profile, firm body and lower syneresis coupled with shorter production time, conjugated application of yoghurt cultures and dahi cultures were tried. Since the shelf-life of dahi is limited, conversion into shrikhand spread may be used as a tool to extend the shelf-life and therefore the market reach towards commercialization into the global market as a potential functional food.Design/Methodology/Approach: Different batches of dahi were made from homogenized (Stage I - 2500 psi, Stage II - 500 psi) and pasteurized (74-78 °C/16-19 Sec) milk, pre-adjusted to 3.15-3.20% fat and 11.40% snf with diverse starter combinations selected upon the extent of post acidification, volatile acid production, syneresis and rheological characteristics. Homogenized, pasteurized and regulated milk was further subjected to a heat-treatment (90°C/10 min) and seeded with selected starter combinations to obtain firm curd intended for shrikhand spread manufacture. Shelf-life of shrikhand spread was evaluated in terms of chemical and microbiological criteria upto 7 days of storage at 8±1°C.Findings: Starter combination of eXactDahi 2+YoFlex Express 1.0 at an incubation temperature-time combination of 45°C/5h was found most suitable for producing dahi with smooth body, higher volatile acidity and low syneresis. Utilization of dahi obtained employing the above starter combination for the manufacture shrikhand spread was suggested and the product was found to retain its goodness when stored for 7 days at 8±1°C. Originality/Value: Conjugated use of yoghurt cultures with dahi cultures was suggested to overcome the drawbacks of traditional process of dahi manufacture suitable for conversion into shrikhand spread. This dahi was found capable of enhancing its dietetic value in addition

    Teaching Engineering Design Through Wearable Device Design Competition (Evaluation)

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    The Wearable Device Challenge was developed at the Nanosystems Engineering Research Center for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST). The Challenge is rooted in the research and innovation ecosystem of the Center and its vision: to have a transformational impact on the way doctors and patients manage wellness through wearable, self-powered health and environmental monitoring systems. At its core, the program teaches middle and high school teachers and students how to apply the engineering design process to solve real-world problems through a project-based approach. The program impacts several hundred students in North Carolina annually through real-world, relevant, hands-on engineering design challenges. Teachers are empowered to introduce engineering design into a variety of both formal and informal educational settings, and students are given the opportunity to explore exciting, cutting-edge applications of science and technology that will inspire them to continue in science, technology, engineering, and mathematics fields

    Power-law corrections to entanglement entropy of horizons

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    We re-examine the idea that the origin of black-hole entropy may lie in the entanglement of quantum fields between inside and outside of the horizon. Motivated by the observation that certain modes of gravitational fluctuations in a black-hole background behave as scalar fields, we compute the entanglement entropy of such a field, by tracing over its degrees of freedom inside a sphere. We show that while this entropy is proportional to the area of the sphere when the field is in its ground state, a correction term proportional to a fractional power of area results when the field is in a superposition of ground and excited states. The area law is thus recovered for large areas. Further, we identify location of the degrees of freedom that give rise to the above entropy.Comment: 16 pages, 6 figures, to appear in Phys. Rev.

    Origin of the butterfly magnetoresistance in a Dirac nodal-line system

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    We report a study on the magnetotransport properties and on the Fermi surfaces (FS) of the ZrSi(Se,Te) semimetals. Density Functional Theory (DFT) calculations, in absence of spin orbit coupling (SOC), reveal that both the Se and the Te compounds display Dirac nodal lines (DNL) close to the Fermi level εF\varepsilon_F at symmorphic and non-symmorphic positions, respectively. We find that the geometry of their FSs agrees well with DFT predictions. ZrSiSe displays low residual resistivities, pronounced magnetoresistivity, high carrier mobilities, and a butterfly-like angle-dependent magnetoresistivity (AMR), although its DNL is not protected against gap opening. As in Cd3_3As2_2, its transport lifetime is found to be 102^2 to 103^3 times larger than its quantum one. ZrSiTe, which possesses a protected DNL, displays conventional transport properties. Our evaluation indicates that both compounds most likely are topologically trivial. Nearly angle-independent effective masses with strong angle dependent quantum lifetimes lead to the butterfly AMR in ZrSiSe

    Cosmic Dynamics in the Chameleon Cosmology

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    We study in this paper chameleon cosmology applied to Friedmann-Robertson-Walker space, which gives rise to the equation of state (EoS) parameter larger than -1 in the past and less than -1 today, satisfying current observations. We also study cosmological constraints on the model using the time evolution of the cosmological redshift of distant sources which directly probes the expansion history of the universe. Due to the evolution of the universe's expansion rate, the model independent Cosmological Redshift Drift (CRD)test is expected to experience a small, systematic drift as a function of time. The model is supported by the observational data obtained from the test.Comment: 16 pages, 9 figure
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