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Q-Switching Pulse Operation in 1.5-μm Region Using Copper Nanoparticles as Saturable Absorber

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Chinese Physics Letters 2017年第3期34卷 41-44页

作者： A.R.muhammad m.T.Ahmad R.zakaria H.R.A.Rahim S.F.A.Z.Yusoff K.S.Hamdan H.H.m.Yusof H.Arof S.W.Harun Department of Electrical Engineering Faculty of EngineeringUniversity of MalayaKuala Lumpur 50603Malaysia Photonics Research Centre Physics DepartmentFaculty of ScienceUniversity of MalayaKuala Lumpur 50603Malaysia

We demonstrate a passively Q-switched erbium-doped fiber laser （EDFL） using a copper nanoparticle （CuNP） thin film as the saturable absorber in a ring cavity. A stable Q-switched pulse operation is observed as the CuNP saturable absorber （SA） is introduced in the cavity. The pulse repetition rate of the EDFL is observed to be proportional to the pump power, and is limited to 101.2kHz by the maximum pump power of 113.7mW. On the other hand, the pulse width reduces from 10.19μs to 4.28μs as the pump power is varied from 26.1 mW to 113.7mW. The findings suggest that CuNP SA could be useful as a potential saturable absorber for the development of the robust, compact, efficient and low cost Q-switched fiber laser operating at 1.5-μm region.

关键词： Cu m Region Using Copper Nanoparticles as Saturable Absorber Q-Switching Pulse Operation in 1.5 SA kHz EDF

Experimental evaluation of a hydrography surface vehicle in four navigation modes

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Journal of Ocean Engineering and Science 2017年第2期2卷 127-136页

作者： Hossein mousazadeh Jafarbiglu Hamid Omrani Elham monhaseri Farshid Kiapei Ali Salmani-zakaria Yousef makhsoos Ashkan mechanical Engineering of Biosystems University of TehranIran mechanical Engineering of Biosystems University of Shahrekord and Expert of Ports and Maritime OrganizationIran

Considering the effectiveness of maritime transportation,a large number of world’s trade is carried by sea and *** ports and harbors are essential for 24 hourly loading/unloading of *** this regard,bathymetry and monitoring of depth data especially in real time manner would be very valuable and *** plot hydrography map of ports and harbors in the bureau as online and with low cost,a Surface Vehicle(SV)is designed and *** vehicle could navigate in four *** could seat on the boat and run by joystick or stand in slipway and control by Remote Controller(RC)or seat in the office and navigate by a user friend graphical *** the boat could navigate fully autonomous without any *** accuracy and precision of four mentioned navigation modes was the main objective of this *** results illustrated that autonomous mode with Standard Deviation(SD)of below 0.5 m was the most precision and comfortable mode,while RC is the more reliable and trustworthy.

关键词： Autonomous,Navigation Hydrography Surface vehicle monitoring

Piper sarmentosum as an antioxidant on oxidative stress in human umbilical vein endothelial cells induced by hydrogen peroxide

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第5期11卷 357-365页

作者： Abdul Hamid HAFIZAH zakaria ZAITON Amom ZULKHAIRI Adenan mOHD ILHAm megat mohd Nordin NOR ANITA Abdullah mahdy ZALEHA Department of Physiology Universiti Kebangsaan Malaysia Medical CentreJalan Raja Muda Aziz50300 Kuala LumpurMalaysia Department of Human Anatomy Division of PhysiologyFaculty of Medicine and Health SciencesUniversiti Putra Malaysia Forest Research Institute of malaysia Department of Obstetrics and Gynecology Universiti Kebangsaan Malaysia Medical Centre

Endothelial cell death due to increased reactive oxygen species(ROS) may contribute to the initial endothelial injury,which promotes atherosclerotic lesion *** sarmentosum(PS),a natural product,has been shown to have an antioxidant property,which is hypothesized to inhibit production of ROS and prevent cell ***,the present study was designed to determine the effects of PS on the hydrogen peroxide(H2O2)-induced oxidative cell damage in cultured human umbilical vein endothelial cells(HUVECs).In this experiment,HUVECs were obtained by collagenase perfusion of the large vein in the umbilical cord and cultured in medium m200 supplemented with low serum growth supplementation(LSGS).HUVECs were treated with various concentrations of H2O2(0-1000 μmol/L) and it was observed that 180 μmol/L H2O2 reduced cell viability by 50% as denoted by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(mTT) *** the above concentration as the positive control,the H2O2-induced HUVECs were concomitantly treated with various concentrations(100,150,250 and 300 μg/ml) of three different extracts(aqueous,methanol and hexane) of ***(mDA),superoxide dismutase(SOD),catalase(CAT) and glutathione peroxidase(GPX) levels showed a significant increase(Pmpared to the negative ***,PS extracts showed a protective effect on HUVECs from H2O2-induced cell apoptosis with a significant reduction in mDA,SOD,CAT and GPX levels(Pmore,PS had exhibited ferric reducing antioxidant power with its high phenolic ***,it was concluded that PS plays a beneficial role in reducing oxidative stress in H2O2-induced HUVECs.

关键词： Piper sarmentosum Human umbilical vein endothelial cells(HUVECs) malondialdehyde Oxidative stress Antioxidant enzymes

A Flat-Gain Double-Pass Amplifier with New Hafnia-Bismuth-Erbium Codoped Fiber

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Chinese Physics Letters 2018年第5期35卷 52-55页

作者： Alabbas A.Al-Azzawi Aya A.Almukhtar P.H.Reddy D.Dutta S.Das A.Dhar m.C.Paul U.N.zakaria S.W.Harun Photonics Engineering Laboratory Department of Electrical Engineering University of Malaya Department of Computer Techniques Engineering Al-Esra'a University College Fiber Optics and Photonics Division CSIR-Central Glass and Ceramic Research Institute Academy of Scientific and Innovative Research CSIR-CGCRI Campus

An efficient and compact double-pass optical fiber amplifier is demonstrated using a newly developed hafnia bismuth erbium co-doped fiber（HBEDF） as a gain medium. The HBEDF is fabricated using a modified chemical vapor deposition in conjunction with solution doping. The fiber has an erbium ion concentration of 12500 *** the optimum length of 0.5 m, the HBEDF amplifier（HBEDFA） achieves a flat gain of 26 d B with a gain variation of less than 1.5 d B within a wavelength region from 1530 to 1560 nm when the input signal and pump power are fixed at-30 d Bm and 140 m W, respectively. On the other hand, at the input signal power of-10 d Bm,the HBEDFA also achieves a flat gain of 14.2 d B with a gain variation of less than 2.5 d B within a wide wavelength region from 1525 to 1570 nm. Compared with the conventional zirconia erbium co-doped fiber based amplifier,the proposed HBEDFA obtains a more efficient gain and lower noise figure. For an input signal of-30 d Bm, the gain improvements of 6.2 d B and 4.8 d B are obtained at 1525 nm and 1540 nm, respectively.

关键词： length A Flat-Gain Double-Pass Amplifier with New Hafnia-Bismuth-Erbium Codoped Fiber

Using Bayesian and Eigen approaches to study spatial genetic structure of moroccan and Syrian durum wheat landraces

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American Journal of molecular Biology 2013年第1期3卷 17-31页

作者： zakaria Kehel Alfonso Garcia-Ferrer miloudi m. Nachit ICARDA Office Rabat Morocco School of Agricultural and Forestry Engineering Cordoba University Cordoba Spain

The mediterranean durum wheat landraces are genetically diverse and important sources for improving resistance to abiotic and biotic stresses and developing adapted and productive durum wheat varieties in the mediterranean region. To study the diversity two distant countries (moroccoandSyria) durum landraces were studied. Fifty-one microsatellites were used as molecular markers tool to determine the genetic structure and spatial adaptation of these landraces. We used two spatially-explicit methods (Bayesian and Eigen) to determine the genetic diversity and structure of a population composed of moroccan (98) and Syrian (90) durum wheat landraces. Non-spatial methods were also applied for comparison. A significant genetic difference was detected between the landraces originated from morocco and Syria. Six subpopulations were revealed for each country using the Bayesian method and the Eigenanalysis, which generated PC1 and sPC1, showed similar structure. Eigenanalysis exhibited a significant global genetic structure for both countries landraces;and showed that neighboring landraces tend to have close genetic profile. The two first axes of PC1 and sPC1 had discriminated four out of the six subpopulations revealed by the Bayesian methodology. Also, our study detected the close relationship between the durum landraces from the coastal areas of Syria and the moroccan landraces from the Atlantic coastal regions where the Phoenicians/Carthaginians had settled in morocco. These results demonstrate the importance of using the spatial models in genetic analysis of durum wheat landraces;and also recommend the use of the easily usable Eigenanalysis to analyze the genetic diversity and structure.

关键词： Durum Wheat Breeding Landraces morocco Syria Genetic Structure Eigenanalysis Bayesian

megalithic Culture and Its Post Visualization： A Short Review on Findings From Archeological Site and Local Tradition in Indonesia

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History Research 2016年第3期6卷 157-163页

作者： Lutfi Yondri Nina Herlina mumuh m. zakaria mundardjito University of Padjadjaran University of Indonesia Indonesia

Long span of megalithic culture development in Indonesia can be seen from its materials remain. It does appear on the sacred and on the profane form. The aim of this article is trying to describe about the megalithic visualization. Some of megalithic aspects such as shape, size, and its material had been applied. megalithic culture in Indonesia is generally found on small size, while the large size is only found in certain locations. It can be concluded the visualization of megalithic culture in Indonesia is no longer in accordance with its etymology as cultural that uses large stone, because small stone and wood are also used as source.

关键词： culture megalithic visualization tradition and material

Sustainability Assessment for Wastewater Treatment Systems—Case Studies in Egypt

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Journal of Environmental Protection 2021年第2期12卷 90-105页

作者： Yousra m. zakaria Ahmed El Gendy Salah El Haggar Construction Engineering Department The American University in Cairo Cairo Egypt mechanical Engineering Department The American University in Cairo Cairo Egypt

Low sanitation coverage is a significant problem in Egypt, especially in rural areas. The Rapid Sustainability Screening (RSS) model was developed to assess the sustainability of wastewater treatment systems (WWTS), both planned and existing, and support decision-makers in selecting alternatives. The model considers the three fundamental sustainability dimensions, namely, environmental, social, and economic. In the present paper, the model was successfully tested by evaluating the sustainability performance of three operating rural WWTS in Egypt (Constructed Wetland (CW)-BeniSuef, Constructed Wetland (CW)-Dakahlia, and Activated Sludge (AS)-Gharbia). CW-BeniSuef was the most sustainable system based upon environmental and social considerations with values of 2.50 and 2.71, respectively. On the other hand, CW-Dakahlia is the most economically sustainable system, with a value of 2.25. The highest sustainability overall ranking system was CW-BeniSuef with overall sustainability of 2.81, followed by CW-Dakahlia with a value of 2.18, and the least sustainable technology is AS-Gharbia (1.72). The RSS model can support the decision-makers and operators during the different phases of a wastewater treatment project development (e.g., feasibility, operation). The model has been developed in a user-friendly and straightforward manner. The simplicity of the model may encourage the decision-makers and EIA practitioners to expand the assessment to consider sustainability rather than focusing on one or two aspects only (m>i.e.m>, environment and society) in isolation of the possible interaction between them.

关键词： Sustainability Assessment Rapid Sustainability Screening Rural Sanitation

Control of Doubly Fed Induction Generator Supplied via matrix Converter for Wind Energy Conversion System

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International Journal of modern Nonlinear Theory and Application 2014年第3期3卷 98-112页

作者： zakaria Kara Kamel Barra Electrical Engineering Larbi Ben M’hidi University Oum El Bouaghi Algeria

The present paper deals with the modeling and control of Wind Energy Conversion System WECS based Doubly Fed Induction Generator DFIG using the slip energy recovery principle. The proposed drive system uses a matrix Converter (mC) to transfer the slip energy of the rotor into the mains instead of using cascaded ac-dc-ac converter whilst the stator side is fixed to the grid. Operation at both sub-synchronous and super-synchronous regions is possible with the proposed drive system. The different level control strategies for maximum power point tracking and active-reactive power are discussed. Simulation results of the proposed doubly fed induction generator drive system show the good performance of the control system strategy for both transient and steadystate conditions.

关键词： WECS DFIG Tip Speed Ratio (TSR) PI Control matrix Converter

An Overview of Bangladeshi Shipbuilding in the Light of Competitive Parameters

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Journal of Shipping and Ocean Engineering 2011年第1期1卷 8-19页

作者： N.m.G. zakaria m.T. Ali K.A. Hossain Department of Naval Architecture and marine Engineering Bangladesh University of Engineering and Technology Dhaka 1000Bangladesh

Shipbuilding in Bangladesh has been considered as the most promising industry in the recent time and the country is dreaming to emerge as a middle income country within a short time by maintaining the upward trend of this sector. However, due to global nature and the long term sustainability of this shipbuilding industry, an investigation of competitiveness in terms of global standard is of prime importance. This paper focuses on studying some crucial competitive factors like labor skill, labor availability, labor man-hour, labor cost ＆ productivity for local shipbuilding in Bangladesh. The analysis also focuses on existing access to the resources like materials, knowledge and capital which are equally important factors for the expansion of shipbuilding. Comparison of these parameters with other nations have been made qualitatively and quantitatively to find the level of our shipbuilding. On the basis of existing condition and future vision, some recommendations have been made which might be useful for accelerating the development of this sector.

关键词： Shipbuilding competitive factor productivity R&D labor cost.