Effect of Cu Layer Thickness on Giant Magnetoresistance Properties of NiCoFe/Cu/NiCoFe Sandwich

Mitra Djamal,Ramli,Yulkifli,Khairurrijal 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

The NiCoFe/Cu/NiCoFe sandwiches were grown onto Si (111) substrate by dc-opposed target magnetron sputtering (dc-OTMS) technique. The growth parameters are: temperature 100 <SUP>0</SUP>C, applied voltage 600 volt, flow rate of Ar gas 100 sccm, and growth pressure 5.2 x10<SUP>-1</SUP> Torr. The effects of Cu layer thickness on giant magnetoresistance (GMR) property of NiCoFe/Cu/NiCoFe sandwich were studied. We have found that the giant magnetoresistance (GMR) ratio is varied depend on the non-magnetic (Cu) layer thickness. The variation of Cu layer thickness of NiCoFe/Cu/NiCoFe sandwich presents an oscillatory behavior of GMR ratio. This oscillation reflects the exchange coupling oscillations between ferromagnetic and antiferromagnetic states, which are caused by an oscillation in the sign of the interlayer exchange coupling between ferromagnetic layers.

Towards A Better Approach for Mastering Industrial Risks From Modeling Accidental Process to Integrating Safety Analysis Techniques Supporting the Identification of Intelligent Safety Decision

Dahmane Djamal,Bahmed Lylia,Bensiali Abdelkarim 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.3

This paper introduces a research aiming at the development of a new approach to mastering industrial risks and prevent accident scenario. Starting from modeling and analyzing accidental process to understand the causes of accidents using quantitative risk assessment and reliability, they are essential issues in modern safety to make reliable decision, and it is new approach used for risk management to identify accident scenarios that may occur at their facilities which are sources of damage. Risk assessment of safety instrumented systems is approaches designed primarily to reduce the existing risk inherent in engineering system to a level considered tolerable and maintain it over time. In this study, the reliability of quantitative risk assessment using fuzzy sets based on event tree analysis and layer of protection analysis is the model proposed to deal with inaccuracy and uncertainty of data, The model proposed to determine the severity of the scenario and determine the safety integrity level SIL using Fuzzy Sets theory. The results which have got by this model is more motivate to deal with uncertainty of which considered as complementary for logical and arithmetic computation. As the accident is a chain of failure events, each related to its (causal) event or events, the early detection and diagnosis of faults in processes is very important, we use Fault Tree Analysis to show the possible malfunctions by enumerating the suspect components and their respective failure modes. Fault diagnosis when error occurs is performed by engineers and analysts performing extensive examination of all data feedback from the system and decisions are made based on threshold values by using fault trees. Since those decision-making tasks are safety critical and must be done promptly, the engineers who manually analyze the data are facing time challenge. To automate this process, we present in this approach to use decision trees to capture the contents of fault trees and detect faults by running the telemetry data through the decision trees in real time. Decision trees are the binary trees built from data samples and can classify the objects into different classes, the decision trees can classify different fault events or normal events. Given a set of data samples, decision trees can be built and trained, and then by running the new data through the trees, classification and prediction can be made.

A Comparative Study of the Degradation of the Erionyl Navy R by Different Oxidation Processes: Chemical, Fenton and Fenton-like

Belaid Kumar Djamal,Elhorri Abdelkader M.,Mered Yassine,Hichem Ellali 한국공업화학회 2022 공업화학 Vol.33 No.4

The oxidative degradation performance of the Erionyl Navy R dye was studied in this article. The investigation mainly focused on a comparative study between chemical oxidations by sodium hypochlorite (NaClO) and hydrogen peroxide (H2O2), and catalytic oxidations including the Fenton (Fe2+-H2O2) and Fenton-Like (Fe2+/ Fe3+/Co2+/ Mn2+-H2O2) or modified Fenton-like (Fe2+/ Fe3+ -NaClO) reactions. A discoloration and degradation of the Erionyl Navy R occurred after 30 minutes, which varies according to the oxidation system involved; 31%, 54%, <20%, 95%, and >96% losses were observed for Co2+-H2O2, Mn2+-H2O2, Fe2+-NaClO, Fe3+-NaClO), and Fe2+-H2O2 and Fe3+-H2O2, respectively.

Uniform in bandwidth rate of convergence of the conditional mode estimate on functional stationary ergodic data

Naâmane Laïb,Djamal Louani 한국통계학회 2016 Journal of the Korean Statistical Society Vol.45 No.1

The aim of this paper is to establish the uniform consistency with rate over a bandwidth interval of the kernel conditional mode estimate whenever functional stationary ergodic data are considered. This kind of result is immediately applicable to proving uniform consistency of kernel-type estimators when the bandwidth h is a function of the data or the location x. Notice that our uniform in bandwidth results are the first ones to be established in this setting. Moreover, the ergodic setting offers a more general framework in regards to the practice than the usual mixing structure.

Recovery and enrichment of heavy metals using new hybrid Donnan dialysis systems combining cation exchange textile and solvent impregnated resin

Dalila Berdous,Djamal-Eddine Akretche 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.7

The purpose of this work is to apply Donnan dialysis coupled with the cation exchange membrane (CMX),the cation exchange grafted textile (CET) and the solvent impregnated resin (SIR) for recovery and enrichment of heavy metal ions from dilute solutions. The influence of some analytical parameters was investigated. The transport results show that the three barriers enhance the diffusion of silver, lead and copper, but the osmosis phenomenon is limited when the transport is carried out through CET and the SIR. The results of enrichments indicate that SIR and CET increase the enrichment factor of less hydrated ions. For instance, and for a volume ratio equal to 10, the values of silver enrichment factor obtained for (CMX/CMX/CMX), (CMX/CET/CMX) and (CMX/SIR/CMX) are equal to 2.5, 8.92and 4.98, respectively. In addition, the use of SIR improves the enrichment of lead, whereas the CET improves the silver’s one.

Eff ect of Boundary Conditions on the Behavior of Stiff ened and Un-Stiff ened Cylindrical Shells

Oussama Temami,Ashraf Ayoub,Djamal Hamadi,Imed Bennoui 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

The eff ect of boundary conditions is very important in the analysis of cylindrical shells, and is rarely studied in the literature due to its diffi cult experimental simulation. For large structures such as shell roofs, the type of boundary supports is among the major factors that can minimize the stresses and defl ections. In this study, experimental and numerical investigations of the eff ect of diff erent boundary supports for stiff ened and un-stiff ened cylindrical shells were conducted. Two diff erent models of the stiff ened and un-stiff ened cylindrical shells with diff erent boundary conditions, “pinned and with rigid diaphragms”, were studied. It was shown that by using rigid diaphragms for cylindrical shells, the defl ections are minimized by 80%, and by (45–50) % for the stiff ened cylindrical shells. From the experimental investigations and the numerical results obtained, the effi ciency of the proposed boundary support types for cylindrical shells is confi rmed, which can result in economic benefi ts.

Enhancement of electrokinetic remediation of lead and copper contaminated soil by combination of multiple modified electrolyte conditioning techniques

Oualid Mohamed Boulakradeche,Ouarda Merdoud,Djamal Eddine Akretche 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.4

Electrokinetic soil remediation is often impeded by the aggregation of small particles, within soil, during the procedure. The soil porous network is subsequently clogged which results in immediate process termination. In order to overcome this limitation, the feasibility of electrokinetic remediation coupled simultaneously with two enhancing techniques was investigated: modified periodic polarity reversal and catholyte pH control. The objective is to keep the soil pores unclogged in order to remove Pb and Cu from soil. Citric acid was used as anolyte, and 1 DCV.cm<SUP>-1</SUP> was applied through the processing cell. This strategy showed 9.0 times better remediation results than that of unenhanced electroremediation. It was mainly owed to: (i) The pH adjustment that kept the catholyte ideally acid, thus avoiding the formation of metal hydroxide precipitates that could clog the soil pores. (ii) An increase of electro osmotic flow due to the modified polarity reversal technique. Approximately 96% of Pb and Cu were removed from soil. Duplicate results were obtained on soil with 10-fold the initial heavy metals concentration. This combined configuration ensured an unclogged path within soil and enhanced electrokinetic mechanisms efficiency against pollutants remediation.

A New Architecture to Offload Network Traffic using OpenFlow in LTE

VENMANI Daniel Philip,Yvon GOURHANT,Djamal ZEGHLACHE 한국산업정보학회 2012 한국산업정보학회논문지 Vol.17 No.1

Next generation cellular applications and smart phone usage generate very heavy wireless data traffic. It becomes ineluctable for mobile network operators to have multiple core network entities such as Serving Gateway and Packet Data Network Gateway in 4G-LTE to share this high traffic generated. A typical configuration consists of multiple serving gateways behind a load-balancer which would determine which serving gateway would service a end-users" request. Such hardware is expensive, has a rigid policy set and is a single point of failure. Another perspective of today"s increasingly high data traffic is that besides it is being widely accepted that the high bandwidth LTE provides is creating bottlenecks for service providers by the increasing user bandwidth demands without creating any corresponding revenue improvements, a hidden problem that is also passively advancing on the newly emerging 4G-LTE that nay need more immediate attention is the network signaling traffic, also known as the control-plane traffic that is generated by the applications developed for smartphones and tablets. With this as starting point, in this paper, we propose a solution, by a new approach considering OpenFlow switch connected to a controller, which gains flexibility in policy, costs less, and has the potential to be more robust to failure with future generations of switches. This also solves the problem of scaling the control-plane traffic that is imperative to preserve revenue and ensure customer satisfaction. Thus, with the proposed architecture with OpenFlow, mobile network operators could manipulate the traffic generated by the control-plane signaling separated from the data-plane, besides also reducing the cost in installing multiple core-network entities.

MULTI-WAVELENGTH FIBRIL DYNAMICS AND OSCILLATIONS ABOVE SUNSPOT WAVE PROPAGATION

MUMPUNI, EMANUEL S.,HERDIWIJAYA, DHANI,DJAMAL, MITRA,DJAMALUDDIN, THOMAS The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

High resolution, multi-wavelength images from the Dutch Open Telescope were used to study the detailed mechanisms that might be involved in the multiple layer solar atmosphere observed in high cadence multi-wavelength observations. With the exceptional data observed for active region NOAA 10789 on 2005 July 13th, we study the changing pattern of the fibril using multi-wavelength tomography of the $H{\alpha}$ line center and blue wing, Ca II H, and the G Band. It is believed that a long fibril that is rooted in the umbra, with longer apparent periodicity, may be due to morphological changes. To determine this, we conduct phase difference and coherency analysis between points along the fibril to understand how the wave propagates.

DETECTION LEVEL ENHANCEMENTS OF GRAVITATIONAL MICROLENSING EVENTS FROM LIGHT CURVES: THE SIMULATIONS

IBRAHIM, ICHSAN,MALASAN, HAKIM L.,DJAMAL, MITRA,KUNJAYA, CHATIEF,JELANI, ANTON TIMUR,PUTRI, GERHANA PUANNANDRA The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2

Microlensing can be seen as a version of strong gravitation lensing where the separation angle of the image formed by light deflection by a massive object is too small to be seen by a ground based optical telescope. As a result, what can be observed is the change in light intensity as function of time; the light curve. Conventionally, the intensity of the source is expressed in magnitudes, which uses a logarithmic function of the apparent flux, known as the Pogson formulae. In this work, we compare the magnitudes from the Pogson formulae with magnitudes from the Asinh formulae (Lupton et al. 1999). We found for small fluxes, Asinh magnitudes give smaller deviations, about 0.01 magnitudes smalller than Pogson magnitudes. This result is expected to give significant improvement in detection level of microlensing light curves.