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

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

QoS Design Consideration for Enterprise and Provider’s Network at Ingress and Egress Router for VoIP protocols

Compliance with the Service Level Agreement (SLA) metric is a major challenge in a Multiprotocol Label Switching Virtual Private Network (MPLS VPN) because mandatory models must be maintained on both sides of the MPLS VPN in order to achieve end-to-end service levels. The end-to-end service of an MPLS VPN can be degraded owing to various issues such as distributed denial of service (DDoS), and Random Early Detection (RED) that prevents congestion and differentiates between legitimate and illegitimate user traffic. In this study, we propose a centralized solution that uses a SLA Violation Detector (SLAVD) and intrusion detection to prevent SLA violation

The stellar mass-size evolution of galaxies from z=7 to z=0

One of the important properties of galaxies is their sizes which correlate with their stellar masses. Evidence is provided by many recent studies that the sizes of galaxies were smaller at higher redshifts compared to galaxies of similar mass in the local Universe. It is essential to understand which physical processes could explain the evolution of galaxy properties and the growth of the galaxies with time. Among different proposed scenarios, each mechanism could affect differently on the growth of stellar mass and hence sizes of galaxies. Consequently, determining these properties is essential to constrain the plausible model(s) for describing galaxy evolution. In this thesis, I will present the study of the mass-size evolution of galaxies from z=7 to z=1. I will also present the stellar mass-size relation for nearby galaxies (z=0), for samples selected using different criteria down to the stellar mass of 10^{9} solar mass. The robustness of size measurement techniques for z=0 and z=1 galaxies is also studied in details.Marie Curie Initial Training Network ELIXIR, PITN-GA-2008-214227, Leiden ObservatoryUBL - phd migration 201

THERMODYNAMIC ANALYSIS OF A COMBINED SOLID OXIDE FUEL CELL WITH A STEAM TURBINE POWER PLANT FOR MARINE APPLICATIONS

The paper presents a combined system to be operated in ship power plants. The system consists of a solid oxide fuel cell (SOFC) and a steam turbine system which utilizes the energy transported with the exhaust gas leaving the fuel cell. The analyzed variant of the combined cycle includes a SOFC and a steam turbine with a single-pressure waste heat boiler. The calculations are performed for two types of SOFC, tubular and planar, each of power output of 18 MW. The assumptions and limits used in the calculations are also presented. The energy optimization of the entire combined ship power plant is carried out, only from a thermodynamic view point. Technical and economic aspects are not taken into consideration. It is found that a high overall efficiency approaching 60% may be achieved with an optimum configuration using SOFC system. The combined system would also reduce emissions, fuel consumption, and improve the total system efficiency

Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications

ABSTRACTStrong restrictions on emissions from marine power plants (particularly SOx, NOx) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heat-recovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency

Power Consumption and Energy Estimation in Smartphones

A developer needs to evaluate software performance metrics such as power consumption at an early stage of design phase to make a device or a software efficient especially in real-time embedded systems. Constructing performance models and evaluation techniques of a given system requires a significant effort. This paper presents a framework to bridge between a Functional Modeling Approach such as FSM, UML etc. and an Analytical (Mathematical) Modeling Approach such as Hierarchical Performance Modeling (HPM) as a technique to find the expected average power consumption for different layers of abstractions. A Hierarchical Generic FSM “HGFSM” is developed to be used in order to estimate the expected average power. A case study is presented to illustrate the concepts of how the framework is used to estimate the average power and energy produced