The Effect of Si and Extrusion Process on the Microstructure and Tensile Properties of Mg-Mg2Si Composite

AbstractThis investigation has been carried out to study the influence of extrusion process on microstructure and tensile properties of Mg-Mg2Si composite with different amounts of Si (3, 5 and 7wt.%). Microstructural examination was carried out using optical microscopy (OM). The cast specimens were extruded at 350°C at different extrusion ratios (6:1, 12:1 and 18:1). The results showed that the specimens with lower Si contents, have higher ultimate tensile strength (UTS) and tensile elongation values. Moreover, there was a considerable improvement in tensile properties for the specimens extruded with the ratio of 12:1 and 18:1 in comparison to the specimens of 6:1. This can be attributed to the significant reduction in size of primary Mg2Si particles from more than 200μm to 20μm, 10μm and 5μm after extrusion with the ratio of 6:1, 12:1 and 18:1, respectively. The highest UTS values were found to be 265MPa for extruded with 1:18 ratio of Mg-3Si composite

PEMBINAAN MORAL DAN KREATIVITAS REMAJA

Entering teen-age, in general, either adolescent son or daugther is hard to be arranged though by its own parents. This matter is problem had by each adolescences, there are four the important matters which become fundamental study at this research, that is: (1) Condition of moral and adolescent creativity in countryside of Bancelok, (2) Effort of moral construction and adolescent creativity in countryside of Bancelok, (3) Resistances faced in moral construction and adolescent creativity in countryside of Bancelok, and also (4) Effort is done to increase the moral construction and adolescent creativity [in countryside of Bancelok. This Research uses approach qualitative. There are four elements becoming the source of informations in this research, that is; old fellow, elite figure society, government officer, and young man figure. Whereas relating to field study (data collecting) using the observation method, interview, and documentation. Later, data that is gathered to be analysed using two approaches, that is: descriptive informative and descriptive analysis

Vectorial characterization of Bloch surface wave via one-dimensional photonic-atomic structure

Use of hot atomic vapor as a new tool for tracing the complex nature of light has become a knowledge-based topic in recent years. In this paper, we examine the polarization ellipse of the Bloch surface wave (BSW) through the effect of a magnetic field on the coupling of these surface waves in BSW-hot atomic vapor cell. For this purpose, we fabricate a one-dimensional photonic crystal-based Bloch wave atom cell, where under different configurations of magnetic field, polarization ellipse of Bloch surface waves has been recorded experimentally. Our results indicate that by applying the magnetic field in different directions, Faraday and Voigt, the characteristics of electromagnetically induced transparency (EIT-like) of hybrid system change. We have used these changes to redefine the geometry of Voigt and Faraday for evanescent waves, as well as to measure the ratio of the components of the elliptical polarized electric field. These characterizations can open new insight into the miniaturized atomic field in high quality and low volumetric areas

FPGA implementation of LDPC soft-decision decoders based DCSK for spread spectrum applications

Spread spectrum (SS) communications have attracted interest because of their channel attenuation immunity and low intercept potential. Apart from some extra features such as basic transceiver structures, chaotic communication would be the analog alternative to digital SS systems. Differential chaos shift keying (DCSK) systems, non-periodic and random characteristics among chaos carriers as well as their interaction with soft data are designed based on low-density parity-check (LDPC) codes in this brief. Because of simple structure, and glorious ability to correct errors. Using the Xilinx kintex7 FPGA development kit, we investigate the hardware performance and resource requirement tendencies of the DCSK communication system based on LDPC decoding algorithms (Prob. Domain, Log Domain and Min-Sum) over AWGN channel. The results indicate that the proposed system model has substantial improvements in the performance of the bit error rate (BER) and the real-time process. The Min-Sum decoder has relatively fewer FPGA resources than the other decoders. The implemented system will achieve 10-4 BER efficiency with 5 dB associate Eb/No as a coding gain

Development of fragility curves for RC bridges subjected to reverse and strike-slip seismic sources

. This paper presents a probabilistic fragility analysis for two groups of bridges: simply supportedand integral bridges. Comparisons are based on the seismic fragility of the bridges subjected toaccelerograms of two seismic sources. Three-dimensional finite-element models of the bridges were createdfor each set of bridge samples, considering the nonlinear behaviour of critical bridge components. When theseismic hazard in the site is controlled by a few seismic sources, it is important to quantify separately thecontribution of each fault to the structure vulnerability. In this study, seismic records come from earthquakesthat originated in strike-slip and reverse faulting mechanisms. The influence of the earthquake mechanismon the seismic vulnerability of the bridges was analysed by considering the displacement ductility of thepiers. An in-depth parametric study was conducted to evaluate the sensitivity of the bridges' seismicresponses to variations of structural parameters. The analysis showed that uncertainties related to thepresence of lap splices in columns and superstructure type in terms of integral or simply supported spansshould be considered in the fragility analysis of the bridge system. Finally, the fragility curves determine theconditional probabilities that a specific structural demand will reach or exceed the structural capacity byconsidering peak ground acceleration (PGA) and acceleration spectrum intensity (ASI). The results alsoshow that the simply supported bridges perform consistently better from a seismic perspective than integralbridges and focal mechanism of the earthquakes plays an important role in the seismic fragility analysis ofhighway bridges

Elastic neural network method for load prediction in cloud computing grid

Cloud computing still has no standard definition, yet it is concerned with Internet or network on-demand delivery of resources and services. It has gained much popularity in last few years due to rapid growth in technology and the Internet. Many issues yet to be tackled within cloud computing technical challenges, such as Virtual Machine migration, server association, fault tolerance, scalability, and availability. The most we are concerned with in this research is balancing servers load; the way of spreading the load between various nodes exists in any distributed systems that help to utilize resource and job response time, enhance scalability, and user satisfaction. Load rebalancing algorithm with dynamic resource allocation is presented to adapt with changing needs of a cloud environment. This research presents a modified elastic adaptive neural network (EANN) with modified adaptive smoothing errors, to build an evolving system to predict Virtual Machine load. To evaluate the proposed balancing method, we conducted a series of simulation studies using cloud simulator and made comparisons with previously suggested approaches in the previous work. The experimental results show that suggested method betters present approaches significantly and all these approaches

Evaluation of the microstructure and mechanical properties of a new modified cast and laser-melted AA7075 alloy

The mechanical properties and microstructure of as-cast and homogenized AA7075 were investigated. This alloy was modified by adding transition elements 0.3%Sc + 0.5%Zr, 1%Ti + 0.2%B, and 1%Fe + 1%Ni for use in additive manufacturing applications. After adding Ti + B and Sc + Zr, the structure became uniform and finer with the formation of the Al3(Sc, Zr) and TiB2 phases. Coarse structures were obtained with the formation of an extremely unfavorable morphology, close to a needle-like structure when Fe + Ni was added. The mechanical properties of the modified alloys were increased compared to those of the standard alloy, where the best ultimate tensile strength (UTS) and yield strength (YS) were obtained in the AA7075-TiB alloy compared to the standard alloy in as-cast and homogenized conditions, and the highest hardness value was provided by Fe + Ni additives. The effect of the laser melting process on the microstructure and mechanical properties was investigated. Single laser melts were performed on these alloys using 330 V and a scanning speed of 8 mm/s. During the laser melting, the liquation of the alloying elements occurred due to non-equilibrium solidification. A change in the microstructures was observed within the melt zone and heat-affected zone (HAZ). The hardness of the laser-melted zone (LMZ) after adding the modification elements was increased in comparison with that of the standard alloy. Corrosion testing was performed using a solution of 100 mL distilled water, 3.1 g NaCl, and 1 mL HCl over 5, 10, and 30 min and 1 and 2 h. The corrosion resistance of the alloy modified with FeNi was low because of the non-uniform elemental distribution along the LMZ, but in the case of modification with ScZr and TiB, the corrosion resistance was better compared to that of the standard alloy. © 2019 by the authors.Ministry of Science and Higher Education of the Russian FederationThe author (Asmaa M. Khalil) gratefully acknowledges financial support from the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of MISiS (Support project for young research engineers)