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 $\sigma_1\gg\sigma_2$, and $\epsilon_1<\epsilon_2$--normal, and while for ``extreme'' {\em reciprocal mixture}--when $\sigma_1\gg\sigma_2$, and $\epsilon_1\ll\epsilon_2$--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

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%

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

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