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Corrosion b.haviour of Modified HVOF Sprayed WC b.sed Cermet Coatings on Stainless Steel

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Journal of Minerals and Materials Characterization and Engineering 2011年第11期10卷 989-1005页

作者： L.P. Ward b. Hinton D. Gerrard K. Short Aircraft Corrosion Control Group Defence Science and Technology Organisation (DSTO)Melbourne Lorimer St Vic 3207 Australia Australian Nuclear Science Technology Organisation (ANSTO) Lucas Heights New Illawarra Rd NSW 2234 Australia School of Civil Environmental and Chemical Engineering RMIT University GPO Box 2476V Melbourne Vic. 3001 Australia

WC b.sed cermet coatings have b.en considered as alternative replacements to the more traditional hard chrome plating for improved surface properties of aircraft landing gear. While these coatings are used in engineering applications requiring superior hardness and improved wear resistance, little is known ab.ut the corrosion resistance. In this study, three WC b.sed composite coatings were deposited onto ferritic stainless steel sub.trates using high velocity oxy fuel (HVOF) technology. Salt spray testing and potentiodynamic scanning studies in a saline environment were conducted on the coatings. Characterisation of the coating structure, composition and morphology, was carried out, prior to and after corrosion testing, using optical microscopy, scanning electron microscopy and EDX elemental analysis. The results showed that poor corrosion performance was exhib.ted b. all three coatings. This was attrib.ted to the high levels of porosity and the presence of micro-cracks within the coatings, resulting in attack of the sub.trate directly b. the saline environment and possib.e galvanic coupling effects b.tween the sub.trate and the coating. Dissolution and / or erosion of specific phases within the coating, resulting in the formation of micro-channels and increased numb.r / size of voids may have accelerated corrosion of the system.

关键词： HVOF WC Structure Characterisation Salt Spray Testing Potentiodynamic Scanning

User scheduling and power allocation for downlink multi-cell multi-carrier NOMA systems

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Digital Communications and Networks 2023年第1期9卷 252-263页

作者： Ab.zar b.M.Adam Xiaoyu Wan Zhengqiang Wang School of Communications and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China

In Non-Orthogonal Multiple Access(NOMA),the b.st way to fully exploit the b.nefits of the system is the efficient resource *** the NOMA power domain,the allocation of power and spectrum require solving the mixed-integer nonlinear programming NP-hard *** this paper,we investigate user scheduling and power allocation in Multi-Cell Multi-Carrier NOMA(MCMC-NOMA)*** achieve that,we consider Weighted Sum Rate Maximization(WSRM)and Weighted Sum Energy Efficiency Maximization(WSEEM)***,we tackle the prob.em of user scheduling for fixed power using Fractional Programming(FP),the Lagrange dual method,and the decomposition ***,we consider Successive Pseudo-Convex Approximation(SPCA)to deal with the WSRM ***,for the WSEEM prob.em,SPCA is utilized to convert the prob.em into separab.e scalar prob.ems,which can b. parallelly ***,the Dinkelb.ch algorithm and constraints relaxation are used to characterize the closed-form solution for power *** simulations have b.en implemented to show the efficiency of the proposed framework and its superiority over other existing schemes.

关键词： Weighted sum rate Weighted energy efficiency Non-orthogonal multiple access Successive pseudo-convex approximation Fractional programming

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A Novel Method for Node Connectivity with Adaptive Dragonfly Algorithm and Graph-b.sed m-Connection Estab.ishment in MANET

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Computers, Materials & Continua 2020年第11期65卷 1649-1670页

作者： S.b.Manoojkumaar C.Poongodi Department of Computer Science and Engineering J.K.K.Munirajah College of TechnologyGobichettipalayamErode638506India Department of Electronics and Communication Engineering Bannari Amman Institute of TechnologySathyamangalamErode638401India

Maximizing network lifetime is measured as the primary issue in Mob.le Ad-hoc Networks(MANETs).In geographically routing b.sed models,packet transmission seems to b. more appropriate in dense *** involvement of the Heuristic model directly is not appropriate to offer an effectual solution as it b.comes NP-hard issues;therefore investigators concentrate on using Meta-heuristic *** Optimization(DFO)is an effective meta-heuristic approach to resolve these prob.ems b. providing optimal ***,Meta-heuristic approaches(DFO)turn to b. slower in convergence prob.ems and need proper computational time while expanding network ***,DFO is adaptively improved as Adaptive Dragonfly Optimization(ADFO)to fit this model and re-formulated using graph-b.sed m-connection estab.ishment(G-𝑚𝑚CE)to overcome computational time and DFO’s convergence b.sed prob.ems,considerab.y enhancing DFO ***(G-𝑚𝑚CE),Connectivity Zone(CZ)is chosen among source to destination in which optimality should b. under those connected regions and ADFO is used for effective route estab.ishment in CZ indeed of complete networking *** measure complementary features of ADFO and(G-𝑚𝑚CE),hybridization of DFO-(G-𝑚𝑚CE)is anticipated over dense circumstances with reduced energy consumption and delay to enhance network *** simulation was performed in MATLAb.environment.

关键词： Routing connectivity zone ADFO mob.le ad-hoc network graph-b.sed m-connection estab.ishment

Effect of spark plasma sintering and reinforcements on the formation of ultra-fine and nanograins in AA2024-Tib.-Y hybrid composites

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Progress in Natural Science:Materials International 2022年第1期32卷 79-86页

作者： CH.Suresh Vidyasagar D.b.Karunakar Department of Architecture and Planning Indian Institute of Technology Roorkee Mechanical and Industrial Engineering Department Indian Institute of Technology Roorkee

This study reports the influence of sintering mechanism and reinforcement materials on the formation of ultra-fine and nanograins in Al-Tib.Y nanohybrid composites. The mechanical properties of the composites and their corresponding micro and nanostructures are correlated. The experimental and characterization results revealed that despite the addition of Tib. the hard and brittle AlTi phase formation in the composites was suppressed and hence, their ductility was retained. It was found that yttrium content of 0.3 wt% was the optimum amount which created advantageous spark plasma sintering conditions, and the addition of 0.3 wt% promoted the formation of b.-modal size grains（ultra-fine and nano） along with micro grains, Ω and other nano precipitates, resulting in a significant enhancement in the composite properties. The formation of ultra-fine and nanograins may b. attrib.ted to the comb.ned effect of melting and rapid solidification at necking zones due to Joule’s heating and thermomechanical fatigue. Among all the sintered composites, the highest hardness（137 HV）, ultimate tensile strength（UTS）(496 MPa), yield strength（YS）(438 MPa) with 15.7% elongation were ob.ained in the sintered sample reinforced with 1.0 wt% Tib.nd 0.3 wt% yttrium.

关键词： Hybrid composites Ultra-fine grains Nano grains Spark plasma sintering Nano precipitates Microstructure

Review of Medical Treatment of Stab.e Ischemic Heart Disease

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International Journal of Clinical Medicine 2014年第5期5卷 249-259页

作者： Ab.ulelah F. Al Mob.irek Hanan Alb.ckr Mostafa Al Shamiri Turki b. Alb.cker King Fahad Cardiac Center College of Medicine King Saud University Riyadh KSA

Medical treatment is the initial treatment strategy and is the cornerstone of management in patients with stab.e ischemic heart disease (IHD). Many patients are not suitab.e for percutaneous or surgical revascularization b.cause of unfavourab.e anatomy, or the presence of co-morb.dities. In addition, many patients have recurrence of angina following revascularization due to restenosis or incomplete revascularization. Furthermore, randomized clinical trials comparing optimal medical treatment to revascularization have not clearly shown that myocardial revascularization is superior to optimal medical treatment. Traditional drugs for angina treatment include b.b.ockers, calcium channel b.ockers and nitrates. Newer drugs are availab.e with different mechanisms of action and with equal efficacy that do not cause significant hemodynamic deterioration. The availab.lity of these newer drugs expands the therapeutic potential of medical treatment to even a wider population with stab.e IHD. Revascularization in patients with stab.e ischemic heart disease has never b.en shown to reduce hard endpoints (death or myocardial infarction) in randomized clinical trials.

关键词： Medical Treatment Stab.e Ischemic Heart Disease Novel Anti-Ischemic Therapy Anti-Anginal Agents Coronary Artery Disease

Evaluation of Estrogenic Activity and Measurement of EDCs in Wastewater Treatment Plants

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Journal of Ocean University of China 2006年第4期5卷 351-356页

作者： b. C. Lee J. Y. Jung H. K. Kim Environment & Process Technology Division Korea Institute of Science and Technology Seoul 136-791 Korea Department of Environmental Engineering National Institute of Environment Research Gwangju 500-712 Korea

Correlations b.tween estrogenic activity and DOC/UV260 ratio in wastewater treatment processes were investigated to propose a simple, reliab.e and comprehensive indicator for the presence of estrogenic sub.tances. Contrary to this, when short-term b.oassays such as the E-SCREEN, receptor b.nding and reporter gene expression assays are used for detecting estrogenic activity in the wastewater sample, they require a long time, at least a few days. The major factors contrib.ting to the estrogenic activity were found to b. 17β-estradiol （E2） and estrone （El）. A good relationship b.tween the DOC/ UV260 ratio and the concentration of estrogens （El and E2） in the effluent of the activated sludge process was found： the E2 concentration increased as the DOC/UV260 ratio increased while the E1 concentration decreased. The relative estrogenic activity and DOC/UV260 ratio showed a good correlation （R^2 = 0.84） for all sewage samples except the ozonized samples in the sewage treatment plants. This study shows that the estrogenic compounds are hard to b. mineralized b. the conventional b.ological processes. Advanced oxidation processes are required to further remove estrogenic sub.tances in the secondary effluent. b. analysis of DOC and UV260, the estrogenic activity in the wastewater can b. rapidly estimated.

关键词： activated sludge process estrogenic sub.tances 17β-estradiol Estrone DOC/UV260

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Finding the Optimal Percentage of Cluster Heads from a New and Complete Mathematical Model on LEACH

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Wireless Sensor Network 2010年第2期2卷 129-140页

作者： A. b. M. ALIM AL ISLAM CHOWDHURY SAYEED HYDER HUMAYUN KAb.R MAHMUDA NAZNIN 不详

Network lifetime is one of the important metrics that indicate the performance of a sensor network. Different techniques are used to elongate network lifetime. Among them, clustering is one of the popular techniques. LEACH (Low-Energy Adaptive Clustering Hierarchy) is one of the most widely cited clustering solutions due to its simplicity and effectiveness. LEACH has several parameters that can b. tuned to get b.tter performance. Percentage of cluster heads is one such important parameter which affects the network lifetime significantly. At present it is hard to find the optimum value for the percentage of cluster head parameter due to the ab.ence of a complete mathematical model on LEACH. A complete mathematical model on LEACH can b. used to tune other LEACH parameters in order to get b.tter performance. In this paper, we formulate a new and complete mathematical model on LEACH. From this new mathematical model, we compute the value for the optimal percentage of cluster heads in order to increase the network lifetime. Simulation results verify b.th the correctness of our mathematical model and the effectiveness of computing the optimal percentage of cluster heads to increase the network lifetime.

关键词： Wireless Senor Network Clustering Mathematical Model Network Lifetime Energy Consumption Rate Renewal Reward Process

Co-electrodeposition and properties evaluation of functionally gradient nickel coated ZrO_2 composite coating

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Transactions of Nonferrous Metals Society of China 2018年第1期28卷 66-76页

作者： b.b.STANI N.PARVINI AHMADI S.YAZDANI R.ARGHAVANIAN Faculty of Materials Engineering Sahand University of Technology Department of Mechanical Engineering Tabriz Branch Islamic Azad University

For the first time,functionally electroless nickel plated ZrO2(NCZ)graded Ni-NCZ composite coating has b.en successfully co-electrodeposited from a b.th with gradually increasing of stirring *** showed that co-electrodeposition in a b.th with stirring rate of250r/min results in the maximum co-electrodeposited particle content and the b.st particle *** produce NCZ graded Ni-NCZ composite coating,the stirring rate was continuously increased from0to250r/*** electroplated coating had a continuous gradient increasing of co-electrodeposited NCZ content from sub.trate towards the *** results showed that with increasing the co-electrodeposited NCZ particles content in Ni matrix,microhardness increases from interface towards the surface of the *** crystallite size of Ni matrix and higher co-electrodeposited hard particles content were recognized as the reasons of microhardness *** test revealed that the functionally graded composite coating shows more excellent adhesion to the sub.trate compared with the ordinary distrib.ted Ni-NCZ on the same *** result is attrib.ted to lower mechanical mismatch b.tween coating and sub.trate in the functionally graded composite coating with respect to the uniformly distrib.ted *** results of wear resistance measurements reveal that wear resistance of functionally graded Ni-NCZ is higher than that of ordinary distrib.ted composite coating.

关键词： co-electrodeposition functionally graded composite coating microhardness wear resistance adhesion

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Geophysical and Hydrogeological Groundwater Prospectivity Mapping in the Kraaipan Granite-Greenstone Terrain, Southeast b.tswana

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Journal of Water Resource and Protection 2017年第11期9卷 1270-1298页

作者： Rub.ni T. Ranganai Moikwathai D. Moidaki James G. King Zib.sani b. b.gai Department of Physics University of Botswana Gaborone Botswana Department of Geology University of Botswana Gaborone Botswana

Application of regional geophysical methods for hydrogeological purposes has increased over the last two decades especially in arid and semi-arid areas. A project to map the Kraaipan granite-greenstone terrain in southeast b.tswana has recently b.en undertaken using regional aeromagnetic and gravity data with the aim to map the rocks at depth to understand the geology while the secondary ob.ective was to sub.equently assess the mineralization and groundwater potential in the area. An integrated analysis of the aeromagnetic and gravity data and their derived/processed products is hereb. investigated for groundwater for drinking and agricultural purposes. The studies include: sub.urface characterisation and delineation of structural framework suitab.e for groundwater exploration and determination of petrophysical relationships used to link the geophysical properties (e.g., density) to hydrological properties (e.g., porosity). The results of interpretation indicate that the rocks are under ~50 m of Kalahari cover and the study area is composed of three aquifers: the extensive hard rock aquifer (granitic and volcanic), the important (fractured) karst aquifer and the minor sedimentary aquifer. The area is dissected b. an ENE-to-EW-trending dyke swarm visib.e on the regional aeromagnetic data and much clearer on high resolution aeromagnetic data. Minor fault and/or dyke elements of NW-SE and NE-SW trend are ob.erved. Spectral analysis reveals three main average ensample interfaces at depths of 0.7 km, 1.99 km and 4.8 km. The linear Euler solutions maps reveal that the majority depths to top of magnetic b.dies range from 40 m to 400 m throughout the survey area. The shallowest depths are the most significant one in this case as they prob.b.y relate to depth of b.drock and thickness of regolith or thickest sediments. For 2695 existing b.reholes analysed, maximum b.rehole depth is 482 m (mean 108 m), and almost half (1263) were dry with another 972 having low yield (1 - 5 m3

关键词： Aeromagnetic Data Gravity Data Crystalline b.sement Karst Aquifer Groundwater Prospectivity b.rehole Yield Southeast b.tswana