An investigation into microstructure and microstructural control of additive layer manufactured Ti-6Al-4V by electron beam melting.

An additive layer manufacturing (ALM) technique, electron beam melting, has been used for the production of simple geometries, from pre-alloyed Ti-6Al-4V powder. Microstructure, texture and mechanical properties achieved under standard conditions have been investigated, alongside numerical modelling of the electron beam and attempts to modify solidification through the addition of boron. Experimentation reveals an asymmetric electron beam which can be manipulated to produce different material responses. The electron beam has been used in this work, at its least powerful, as a means of preheating powder particles and, at its most powerful; to produce what is effectively a macro-scale electron beam weld. Numerical modelling and extraction of solidification parameters reveal that solidification occurs in the columnar region - columnar grains are observed experimentally and are a feature of the process. I Observed microstructures indicate a complicated thermal history that is capable of producing diffusion-less and diffusional transformation products. Electron backscatter diffraction (EBSD) and prior ~ grain reconstruction reveal a strong texture perpendicular to the build axis. Mechanical properties, tested over a range of build temperatures, are sensitive to temperature over the tested range of 625 - 700 °e. Attempts to disrupt columnar solidification via the addition of boron to Ti-6Al-4V, before subsequent EBM processing, were unsuccessful. Solidification remained in the columnar regime with no refinement in grain morphology observed

Implementation and investigation of a real-time optical 16-QAM transmission system with FPGA-based coherent receiver

Diese Dissertation stellt die erste Echtzeitübertragung von 16-QAM mit FPGA-basierter DSPU vor. 2.5 Gb/s wurden dabei über 20 und 100 km übertragen und kohärent (heterodyn) in Echtzeit empfangen. Die Bitfehlerquote (BER) lag dabei unterhalb der Schwelle moderner Fehlervorwärtskorrekturverfahren mit 7% Overhead. Mit BPS (Blind Phase Search) und QPSK partitioning (QPSKP) wurden zwei unterschiedliche Techniken zur Phasenrückgewinnung implementiert und durch Echtzeitmessung verglichen. Der Einfluss der Auflösung der erforderlichen Analog-Digital-Umsetzer (ADC) wurde ebenfalls untersucht, welche ebenfalls eine Herausforderung für kohärente Echtzeitübertragung darstellt. Der Einfluss von Phasenrauschen wird hier auch gezeigt, welches vorwiegend von den verwendeten Lasern, optischen Verstärkern und nichtlinearen Effekten in den optischen Fasern abhängt. Darüber hinaus wurden verschiedene Arbeitspunkte des 16-QAM-Modulators in Echtzeit getestet und die optimalen Bedingungen für eine minimale Bitfehlerquote gefunden.In this dissertation the first published real-time implementation of a 16-QAM transmission system with FPGA-based DSP is presented. 2.5 Gb/s coherent 16-QAM data has been optically transmitted over 20 and 100 km and synchronously received by heterodyning in a real-time I&Q receiver, with BER below the threshold of a state-of-the-art FEC (7% overhead). Two techniques of feed-forward carrier phase recovery (Blind Phase Search (BPS) and QPSK partitioning (QPSKP)) were tested in a real-time transmission experiment and compared with each other. The influence of the required resolution of the analog-to-digital converter (ADC) has been investigated, which is a challenge of real-time coherent transmission systems. The influence of phase noise in 16-QAM, which is mainly contributed from laser sources, optical amplifiers, and nonlinear effects in optical fibers is also shown. Moreover, different operation points of a 16-QAM modulator were tested in real-time and an optimal condition is found which minimizes the BER.Tag der Verteidigung: 10.09.2013Paderborn, Univ., Diss., 201

Efficient cryptography techniques for image encryption in cloud storage

In recent years and with the great progress of the use of cloud computing and their uses that covered most aspects of modern life as well as provide a variety of services, such as the formation of computing resources, cost control, sustainability, mobility and service flexibility. However, there are challenges to cloud computing, the most important of which is data security and transmission. Cryptographic is the science of protecting data by converting data (plain text) into an incomprehensible format (cipher text) for unauthorized individuals through the use of mathematical techniques. This paper provides work for the most common encryption algorithms that are utilized to encryption of data in cloud computing and presented some of papers that based on the most common cryptographic techniques such as DES, 3DES, Blowfish, AES, RSA, D-H, ECC And others. This way paves the way for finding the suitable encryption algorithm to protect the data in the cloud environment. The AES outperforms the other algorithms in term of encryption time

Modeling of Cold-formed Purlins-sheeting Systems

Purlin-sheeting systems used for roofs and walls commonly take the form of cold-formed channel or zed section purlins, screw-connected to corrugated sheeting. This paper presents two nonlinear elasto-plastic finite element models, capable of predicting the behaviour of purlin-sheeting systems without the need for either experimental input or over simplifying assumptions. The first model incorporates both the sheeting and the purlin while the second, a simplified version of the first model, includes only the purlin. Both models are able to account for cross-sectional distortion of the purlin, the flexural and membrane restraining effects of the sheeting, and failure of the purlin by local buckling or yielding. The validity of the models is shown by their good correlation with experimental results

Comparative Leaf Anatomy of the Genus Hordeum L. (Poaceae) in Iraq

In this study leaf anatomical characters among the species of the genus Hordeum L. have been evaluated. In Iraq, Hordeum is represented by eight species, namely Hordeum bulbosum L., H.distichon L., H.geniculatum All., H.glaucum Steud., H.leporinum Link, H.marinum var. marinum Huds., H.marinum var. pubescens (Guss.) Nevski, H. spontaneum var. spontaneum C. Koch, H.spontaneum var. proskowetzii Nab., and H. vulgare L. This genus one of the most economically important cereal crops in the tribe Triticeae, has a worldwide distribution mainly in temperate and dry regions of the world. The main objective of this study is to asses the significance of anatomical characteristics of the leaves. For this purpose transverse sections and leaf surfaces were examined. Anatomic features show that leaf blades vary between the taxa in both qualitative and quantitative values. Sclerenchymatic cells, silica bodies, and stomata, furrow and ribs properties, the existence of midrib and bulliform cells, and indumentum properties such as length of prickles and macro-hairs are all included in these diagnostic characteristics . Keywords: Leaf anatomy, Hordeum, Poaceae

PCR Detection of Putative Hemolysin and Aerolysin Genes in An Aeromonas Hydrophila Isolates from Diarrhea in Babylon Province

Aeromonas spp are considered as apportunistic infection and enterotoxgenic pathogen and can cause severe diarrhea . A total  of one hundred and forty two stool samples were collected from patients with diarrhea at Babylon hospital for maternity and pediatrics of a period  between December 2012 to June 2013.The 6(4.22%  )strains of Aeromonas hydrophila were isolated from 142samples of diarrhea stools .The Aeromonas  hydrophila identified based on colony and microscopic morphology ,biochemical tests and confirmed by Api 20E .Then investigation was done on  hemolysin ,All the isolates of Aeromonas hydrophila have the ?- hemolytic activity on the blood agar .the polymerase chain reactions carried out to detect the presences of hemolysin and aerolysin genes in 6 Aeromonas hydrophila isolates .A100%(6 isolates)of  Aeromonas hydrophila isolates were contained hemolysin genes (ahh 1a)and 50%(3 isolates)  were contain aerolysin gene (aerA).the band appearance in amplified gene bacteria shows molecular weight of hemolysin (130  p) and the molecular weight of aerolysin ( 309  bp) . Key word:Aeromonas, aerolysin, hemolysin, PC

Estimating the lifetime and Reentry of the Aluminum Space Debris of Sizes (1-10 cm) in LEO under Atmosphere Drag Effects

  This study concerns in addressing the lifetime and reentry of the space debris in LEO which extends from 200 to 1200 km. In this study the new Computer programs are designed to simulate orbit dynamics of space debris lifetime and reentry under atmospheric drag force by using Runge-Kutta Method to solve the differential equations of drag force and this model was adapted with the Drag Thermosphere Model (DTM78, 94), the Aluminum 2024 space debris in certain size (1-10 cm) were used in this study, which is frequently employed in the structure of spacecraft and aerospace designs. The selected atmospheric model for this investigation is the drag thermospheric models DTM78 and DTM94, because of this dependence on solar and geomagnetic activities. It has been found that the lifetime of the space debris increases with increasing perigee altitudes. It has been found that the elliptical shape of the debris orbit would change gradually into a circular shape, then its kinetic energy would be transformed into heat and hence debris destroy in the dense atmosphere

Testing The Effective Performance Of Ofdm On Digital Video Broadcasting

One of the most exciting areas in telecommunications and networking is wireless technology. The rapid growth of mobile telephone uses various satellite services. So, the present work deals with high data stream applications of Digital Video Broadcasting (DVB), which takes an important place in the studies and development researches due to its direct contacts on the human daily life. In this design the focusing is on the modern types of DVB where modified module of the Terrestrial DVB for Handheld terminals (DVB-H) is used and it was simulated to perform the physical layer of the designed system. Different modes of DVB-H with high bit rate of Orthogonal Frequency Division multiplexing (OFDM) and high number of sub-carriers are considered to show the effect of Coded Orthogonal Frequency Division multiplexing (COFDM) on the system SNR using the convolutional encoding. The modes are tested to show the characteristics of each type involving BER calculation. The obtained results show the effect of OFDM in the designed system by evaluating it using AWGN and mobile multipath channels. These demonstrate the effective of OFDM over single carrier systems where the complexity and cost of implementation are both increaseed by increasing number of carrier. The elimination of ISI is achieved using efficient coding techniques with small guard time. The 4k mode shows good performance in mobile reception, providing satisfactory and reasonable receiver cost/complexity. The Peak Signal to Noise Ratio (PSNR) measurement of the reconstructed received image pixels provides more mentality and good comparing method than the BER measuring. The obtained results are compared between the PSNR of each reconstructed images for different modes with the corresponding transmitting SN

Design And Implementation Of High Speed Complex Multiplier Using Fpga

Multiplication is an important part in real-time digital signal processing (DSP). The present work deals with the design and implement of complex  ultiplier/mixer using Field Programmable Gate Array (FPGA) chip with low cost and high speed. Two devices of FPGA are chosen to implement the design; to achieve the task of mixer system implementation. The rules that are important for such implementation are proposed in order to reach the minimum cost and high speed requirement for the individual component of mixer system. These components are software simulated using VHDL language, with software called MODELSIM version SE-EE5.4a. Since mixer is important in any digital receiver because of high speed need, so different multiplier method are proposed with different data resolution and different worst case of additional noise. To achieve high speed data, a parallel tree multiplier is used with Wallace tree method which is optimal in speed but it has a complicated routing that makes it impractical to implement, because of this, we present a modification for fast parallel multiplier using both Wallace tree and Booth algorithm to achieve a sufficient design for most of DSP application. The proposed design of mixer is simulated using ISE4.1i and results in successful achievement of its desired specification. The final implementation of programmable (4, 8, 16, 32 and 64) bit mixer data input resolution is achieved using Virtex-II devices and also implemented in LP-2900 CPLD device. The resulting performance depending on multiplier method are viewed in mixer cost. However, the routing is much more regular with great reduction in FPGA cost and it is achieved for the desired mixer when compared with other methods