1,249 research outputs found
Dielectric mixtures -- electrical properties and modeling
In this paper, a review on dielectric mixtures and the importance of the
numerical simulations of dielectric mixtures are presented. It stresses on the
interfacial polarization observed in mixtures. It is shown that this
polarization can yield different dielectric responses depending on the
properties of the constituents and their concentrations. Open question on the
subject are also introduced.Comment: 40 pages 12 figures, to be appear in IEEE Trans. on Dielectric
On micro-structural effects in dielectric mixtures
The paper presents numerical simulations performed on dielectric properties
of two-dimensional binary composites on eleven regular space filling
tessellations. First, significant contributions of different parameters, which
play an important role in the electrical properties of the composite, are
introduced both for designing and analyzing material mixtures. Later, influence
of structural differences and intrinsic electrical properties of constituents
on the composite's over all electrical properties are investigated. The
structural differences are resolved by the spectral density representation
approach. The numerical technique, without any {\em a-priori} assumptions, for
extracting the spectral density function is also presented.Comment: 24 pages, 8 figure and 7 tables. It is submitted to IEEE Transactions
on Dielectrics and Electrical Insulatio
Relations Attitude Towards Mathematics Lesson, Anxiety and Academic Success
In this particular study attitude towards mathematics lessons and relation between anxiety and academic success had been explored. Though as a result of the comparative analysis of the study gender, teacher, class and the most popular and favorite lesson were determined to cause significant differences of opinion with regard to attitude towards mathematics lesson in some cases, based on structural equation modeling substantive and significant impact had been observed only for the most popular and favorite lesson. Besides, anxiety towards mathematics lesson was determined to have a mediation impact on the relation between attitude towards mathematics lesson and anxiety. Based on evaluation of the findings obtained as a result of the study and these findings’ relation with the studies available in the relevant literature, certain significant conclusions are obtained. First of all, the most popular and favorite lesson as one of the independent variables of the study may be seen as an indicator of the attitude towards mathematics lesson. The most popular and favorite lesson variable differentiated academic success in a significant manner. In the meantime, a significant relation was determined between attitude as a scaling factor and success in mathematics lesson. Again in line with positive attitude, anxiety had been determined to be effective is projection and prediction of success with its intermediary impact. We absolutely recommend educators to take attitude into consideration in terms of success in mathematics lesson as a consequence of our study. In addition to this, we may assert a claim that they will achieve success in mathematics lesson provided that they include activities to enrich learning process in a positive manner and they take anxiety into consideration throughout the process
Economic policy during the long 19th century
This chapter provides an overview of the political decision-making process and the modernisation of the state apparatus during the 19th century. It discusses the legal capacity of the states which acted either as a constraint on policymakers or enabled them to pursue and enforce a certain set of economic decisions. At the beginning of the 19th century, the region was divided up among the Austrian Empire, the Ottoman Empire, and the Russian Empire. The late 19th century and the remaining time up to the war saw a rise in protectionism, a growing share of state ownership in infrastructure, and a growing government share in gross domestic product (GDP). In Russia, where serfs belonged either to the state or to private persons and accounted for more than half the population at the beginning of the 19th century, the emancipation of state serfs started in the 1840s, and that of serfs in the private sector followed in 1861
Extracting spectral density function of a binary composite without a-priori assumption
The spectral representation separates the contributions of geometrical
arrangement (topology) and intrinsic constituent properties in a composite. The
aim of paper is to present a numerical algorithm based on the Monte Carlo
integration and contrainted-least-squares methods to resolve the spectral
density function for a given system. The numerical method is verified by
comparing the results with those of Maxwell-Garnett effective permittivity
expression. Later, it is applied to a well-studied rock-and-brine system to
instruct its utility. The presented method yields significant microstructural
information in improving our understanding how microstructure influences the
macroscopic behaviour of composites without any intricate mathematics.Comment: 4 pages, 5 figures and 1 tabl
Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency
A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching motions, and the phase shift between them. Computations are performed in parallel in a work station cluster. The numerical simulations show that high thrust values may be obtained at the expense of reduced efficiency. For high efficiency in thrust generation, the induced angle of attack of the airfoil is reduced and large scale vortex formations at the leading edge are prevented.
Signs of low frequency dispersions in disordered binary dielectric mixtures (50-50)
Dielectric relaxation in disordered dielectric mixtures are presented by
emphasizing the interfacial polarization. The obtained results coincide with
and cause confusion with those of the low frequency dispersion behavior. The
considered systems are composed of two phases on two-dimensional square and
triangular topological networks. We use the finite element method to calculate
the effective dielectric permittivities of randomly generated structures. The
dielectric relaxation phenomena together with the dielectric permittivity
values at constant frequencies are investigated, and significant differences of
the square and triangular topologies are observed. The frequency dependent
properties of some of the generated structures are examined. We conclude that
the topological disorder may lead to the normal or anomalous low frequency
dispersion if the electrical properties of the phases are chosen properly, such
that for ``slightly'' {\em reciprocal mixture}--when , and
--normal, and while for ``extreme'' {\em reciprocal
mixture}--when , and --anomalous
low frequency dispersions are obtained. Finally, comparison with experimental
data indicates that one can obtain valuable information from simulations when
the material properties of the constituents are not available and of
importance.Comment: 13 pages, 7 figure
Neuroprotective effects of Potentilla fulgens on spinal cord injury in rats: an immunohistochemical analysis
Background: This examination was performed to research the advantage of the antioxidant impact of Potentilla fulgens on spinal cord injury (SCI) in rats.
Materials and methods: In the SCI model of this examination, the tolerably serious lesion was performed at the L1–L2 spinal segmental level. SCI animals were given P. fulgens 400 mg/kg/day, intraperitoneally. At 7 days post-lesion, exploratory rats were executed after intraperitoneal administration 7 ketamine HCL (0.15 mL/100 g body weight). Spinal cord specimens were taken for histological examination or assurance of malondialdehyde (MDA) and glutathione (GSH) levels and myelope- roxidase (MPO) action. SCI caused a remarkable decline in spinal cord GSH content, trailed by noteworthy increments in MDA levels and MPO action.
Results: Degenerative changes in some multipolar and bipolar nerve cells and pyknotic changes in the nuclei of glial cells were likewise noticed. Remarkable development was seen in cells and vascular structures of P. fulgens treated groups when contrasted with untreated groups.
Conclusions: Potentilla fulgens application may influence angiogenetic impro- vement in vein endothelial cells, reduce inflammatory cell aggregation by influ- encing cytokine system and may make apoptotic nerve cells and neuroprotective component in glial cells
Proactive multi-tenant cache management for virtualized ISP networks
The content delivery market has mainly been dominated by large Content Delivery Networks (CDNs) such as Akamai and Limelight. However, CDN traffic exerts a lot of pressure on Internet Service Provider (ISP) networks. Recently, ISPs have begun deploying so-called Telco CDNs, which have many advantages, such as reduced ISP network bandwidth utilization and improved Quality of Service (QoS) by bringing content closer to the end-user. Virtualization of storage and networking resources can enable the ISP to simultaneously lease its Telco CDN infrastructure to multiple third parties, opening up new business models and revenue streams. In this paper, we propose a proactive cache management system for ISP-operated multi-tenant Telco CDNs. The associated algorithm optimizes content placement and server selection across tenants and users, based on predicted content popularity and the geographical distribution of requests. Based on a Video-on-Demand (VoD) request trace of a leading European telecom operator, the presented algorithm is shown to reduce bandwidth usage by 17% compared to the traditional Least Recently Used (LRU) caching strategy, both inside the network and on the ingress links, while at the same time offering enhanced load balancing capabilities. Increasing the prediction accuracy is shown to have the potential to further improve bandwidth efficiency by up to 79%
Online Fault Classification in HPC Systems through Machine Learning
As High-Performance Computing (HPC) systems strive towards the exascale goal,
studies suggest that they will experience excessive failure rates. For this
reason, detecting and classifying faults in HPC systems as they occur and
initiating corrective actions before they can transform into failures will be
essential for continued operation. In this paper, we propose a fault
classification method for HPC systems based on machine learning that has been
designed specifically to operate with live streamed data. We cast the problem
and its solution within realistic operating constraints of online use. Our
results show that almost perfect classification accuracy can be reached for
different fault types with low computational overhead and minimal delay. We
have based our study on a local dataset, which we make publicly available, that
was acquired by injecting faults to an in-house experimental HPC system.Comment: Accepted for publication at the Euro-Par 2019 conferenc
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