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High Velocity Forming of Aluminum Cylindrical Cups-Experiments and Numerical Simulations

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Journal of Materials Science & technology 2007年第2期23卷 230-236页

作者： Mustafa yasar Faculty of technical Education ZKU/Zonguldak Karaelmas UniversityKarabukTurkey

A new two stage detonation forming machine was developed and cylindrical aluminum cups were formed by using gas detonation forming technology. the forming process was analyzed with the explicit finite element method with various parameters and ANSYS/LS-DYNA software. Defects of wrinkling and rupture were predicted for some forming conditions. the strain and the thickness distribution results were in good agreement with the experimental results. It was seen that thinning and forming mainly take place during the one fourth of the time. the effects of detonation pressure and blank holding force on the deformation of the work pieces were discussed. the numerical results were compared with those obtained in the experiments.

关键词： Detonation forming Explicit finite element Detonation pressure

Predictive plots for conical pick performance using mechanical and elastoplastic properties of rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第5期12卷 1027-1035页

作者： Serdar yasar Department of Mining Engineering Karadeniz Technical UniversityTrabzon61080Turkey

Conical picks are by far the most widely used drag type cutting tools employed on partial face rock excavation *** cutting force and specific energy are two important design parameters for the conical pick performance,and the rock cutting testing is considered as the promising tool for determining these *** the absence of an instrumented cutting rig,researchers generally rely on empirical predictive *** this,this paper suggests predictive plots for estimating the cutting force and specific energy,in consideration of the cutting depth to define the cuttability with conical *** this context,rock cutting tests were carried out on six volcanic rock samples with varying cutting depths using the unrelieved and relieved cutting *** cutting force and specific energy were correlated with the uniaxial compressive strength,Brazilian tensile strength,elasticity modulus,and plasticity *** plots were proposed for different cutting depths in the unrelieved and relieved cutting modes and exponential relationships were obtained among the cuttability parameters,and mechanical and elastoplastic properties of rocks.

关键词： Performance prediction Rock cutting tests Specific energy Cutting force Plasticity index

Does Monetary Support Increase the Number of Scientific Papers？ An Interrupted time Series Analysis

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Journal of Data and Information Science 2018年第1期3卷 19-38页

作者： yasar tonta Department of Information Management Faculty of Letters Hacettepe University 06800 Beytepe Ankara Turkey

Purpose： One of the main indicators of scientific production is the number of papers published in scholarly journals. turkey ranks 18th place in the world based on the number of scholarly publications. the objective of this paper is to find out if the monetary support program initiated in 1993 by the turkish Scientific and technological Research Council （tUBItAK） to incentivize researchers and increase the number, impact, and quality of international publications has been effective in doing ***/methodology/approach： We analyzed some 390,000 publications with turkish affiliations listed in the Web of Science （WoS） database between 1976 and 2015 along with about 157,000 supported ones between 1997 and 2015. We used the interrupted time series （ItS） analysis technique （also known as ＂quasi-experimental time series analysis＂ or ＂intervention analysis＂） to test if tOBItAK＇s support program helped increase the number of publications. We defined ARIMA （1,1,0） model for ItS data and observed the impact of tOBitAK＇s support program in 1994, 1997, and 2003 （after one, four and 10 years of its start, respectively）. the majority of publications （93%） were full papers （articles）, which were used as the experimental group while other types of contributions functioned as the control group. We also carried out a multiple regression ***： tUBItAK＇s support program has had negligible effect on the increase of the number of papers with turkish affiliations. Yet, the number of other types of contributions continued to increase even though they were not well supported, suggesting that tUBItAK＇s support program is probably not the main factor causing the increase in the number of papers with turkish affiliations. Research limitations： Interrupted time series analysis shows if the ＂intervention＂ has had any significant effect on the dependent variable but it does not explain what caused the increase in the number of papers if it was not the intervention. Moreover, excep

关键词： Performance-based research funding systems Publication subsidies Publicationsupport programs Interrupted time series analysis

Drag pick cutting tests: A comparison between experimental and theoretical results

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第5期10卷 893-906页

作者： Serdar yasar Ali Osman Yilmaz Department of Mining Engineering Karadeniz Technical University

this paper aims at reporting the results of a number of drag pick cutting tests on selected igneous rock samples to compare the experimentally determined maximum cutting force （FC） values with theoreti- cally estimated ones. First, a review on theoretical rock cutting models proposed for both chisel and conical picks was presented in detail. Experimental study consists of both chisel and conical pick cutting tests in unrelieved （single-pick） cutting mode with varying cutting depths. FC＇ values were determined from experimental results, and theoretical models were utilized to compute FC for all cutting conditions. Computed and experimentally determined F（ data were then compared for a referenced cutting depth. It is shown that the theoretical models might overestimate or underestimate FC＇ and cannot give reliable results. Finally, explanations for these mismatches were presented.

关键词： Rock cutting mechanics Rock cutting tests Vertical rock cutting rig (VRCR) Cutting force Rock cutting theories

Multiple exp-function method for soliton solutions of nonlinear evolution equations

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Chinese Physics B 2017年第7期26卷 20-26页

作者： Yakup Yιldιrιm Emrullah yasar Department of Mathematics Faculty of Arts and Sciences Uludag University

We applied the multiple exp-function scheme to the（2＋1）-dimensional Sawada-Kotera（SK） equation and（3＋1）-dimensional nonlinear evolution equation and analytic particular solutions have been deduced. the analytic particular solutions contain one-soliton, two-soliton, and three-soliton type solutions. With the assistance of Maple, we demonstrated the efficiency and advantages of the procedure that generalizes Hirota＇s perturbation scheme. the obtained solutions can be used as a benchmark for numerical solutions and describe the physical phenomena behind the model.

关键词： (2+1)-dimensional Sawada-Kotera(SK) equation (3+1)-dimensional nonlinear evolution equation(NLEE) multiple exp-function method multiple wave solutions

An Optimization Approach of IoD Deployment for Optimal Coverage Based on Radio Frequency Model

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2627-2647页

作者： tarek Sheltami Gamil Ahmed Ansar yasar Computer Engineering Department Interdisciplinary Research Center of Smart Mobility and LogisticsKing Fahd University of Petroleum and MineralsDhahran31261Saudi Arabia transportation Research Institute(IMOB) Hasselt UniversityHasselt3500Belgium

Recently,Internet of Drones(IoD)has garnered significant attention due to its widespread ***,deploying IoD for area coverage poses numerous limitations and *** include interference between neighboring drones,the need for directional antennas,and altitude restrictions for *** challenges necessitate the development of efficient *** research paper presents a cooperative decision-making approach for an efficient IoDdeployment to address these challenges *** primary objective of this study is to achieve an efficient IoDdeployment strategy thatmaximizes the coverage regionwhile minimizing interference between neighboring *** deployment problem,the interference increases as the number of deployed drones increases,resulting in bad quality of *** the other hand,deploying a few drones cannot satisfy the coverage *** accomplish this,an enhanced version of a concise population-based meta-heuristic algorithm,namely Improved Particle SwarmOptimization(IPSO),is *** objective function of IPSO is defined based on the coverage probability,which is primarily influenced by the characteristics of the antennas and drone altitude.A radio frequency(RF)model is derived to evaluate the coverage quality,considering both Line of Sight(LOS)and Non-Line of Sight(NLOS)down-link coverage probabilities for ground *** is assumed that each drone is equipped with a directional antenna to optimize coverage in a given *** simulations are conducted to assess the effectiveness of the proposed *** demonstrate that the proposed method achieves maximum coverage with minimum transmission ***,a comparison is made against Collaborative Visual Area Coverage Approach(CVACA),and a game-based approach in terms of coverage quality and convergence *** simulation results reveal that our approach outperforms both CVACA and the gamebased schemes in terms of coverage an

关键词： IoD line of sight optimal deployment IPSO RF model

Selection of promising chestnuts(Castanea sativa) among wild growing trees from southern Mediterranean region forests of turkey

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Journal of Forestry Research 2016年第2期27卷 349-355页

作者： Yilmaz Ormeci yasar Akca Sezai Ercisli Department of Horticulture Agriculture FacultyGaziosmanpasa University Department of Horticulture Agriculture Faculty Ataturk University

turkey ranked third place in the world for chestnut production after China and South Korea and the country has unique chestnut forests including valuable and diverse chestnut genotypes. this study was conducted to select superior chestnut genotypes within seedling popu- lations found in natural wild grown chestnut forest located in Isparta province in turkey during 2010-2011 years. A total of 2500 wild grown chestnut trees were examined on the field first year and among them the most promising 22 genotypes were chosen according to relatively high yield capacity, earliness, tolerance to chestnut blight （Cryphonectria parasitica）, ink disease （Phytopthora cambivora）, and fruit quality characteristics. the selected 22 genotypes were evaluated for their detailed morpho- logical, phenological and pomological traits in 2010 and 2011. According to average of 2 years, nut weight, the number of nut per kilogram, nut width, nut length, nut height and nut shell thickness of 22 promising genotypes ranged from 10.26 to 22.32 g, 97.47 to 44.80/kg, 26.80 to 42.47, 16.92 to 25.91, 27.74 to 39.73, and 0.26 to 1.01 mm, respectively. the ash, crude protein, and total fat content of kernels were between 0.85 to 1.94, 3.69 to 7.06 and 1.32 to 4.52, respectively. the genotypes were evaluated with weighted ranking method and the highest general quality score was observed in genotypes of IY17, IYO1, IY42, IY43 and IY12.

关键词： Castenea sativa Mill. Forest fruits Selection tree breeding

Effect of Si on austenite stabilization,martensite morphology,and magnetic properties in Fe-26%Ni-x%Si alloys

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 192-196页

作者： H.Gungunes E.yasar M.Dikici Science and Arts Faculty Department of Physics Hitit University Science and Arts Faculty Department of Physics Kirikkale University

the effect of Si on the austenite stabilization, martensite morphology, and magnetic properties in Fe-26%Ni-x%Si （x=3.5, 5, and 6） alloys have been studied by means of transmission electron microscopy （tEM） and M？ssbauer spectroscopy techniques. tEM observations reveal that the martensite morphology is closely dependent on the Si content. the volume fraction changes of martensite and austenite phases, the hyperfine magnetic field, and isomer shift values have been determined by Mssbauer spectroscopy. the M？ssbauer study reveals that the hyperfine magnetic field, the isomer shift values and the volume fraction of martensite decrease with increasing Si content.

关键词： ferrous alloys martensite morphology magnetic properties transmission electron microscopy (tEM) m6ssbauer spectroscopy

Decolorization of Blue CL-BR dye by AOPs using bleach wastewater as source of H_2O_2

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Journal of Environmental Sciences 2007年第10期19卷 1183-1188页

作者： Abdullah yasar Nasir Ahmad Aamir Amanat Ali Khan Anwer Yousaf Directorate of Research and Development University of the PunjabLahore-Pakistan41-Kamran BlockAUama lqbal TownLahore-Pakistan.

this research was focused on the investigation of the efficacy of advanced oxidation processes （Fenton, ozonation and UV/H2O2） for decolorization of reactive azo dye （Blue CL-BR） using bleach wastewater as possible source of H2O2. All the experiments were performed on the laboratory scale set-up. the results showed that colour removal efficiencies by UV or bleach （H2O2） alone were not so efficient. Fenton process with bleach wastewater was found to be the most effective at process conditions such as pH of 3 and HEO2/Fe^2＋ ratio of 24：1, resulting in 64% colour removal. Almost complete colour removal, i.e., 99% and 95% were achieved by UV//H2O2 and UV/bleach wastewater in 30 and 60 min, respectively. Ozonation proved an efficient method for decolorization of Blue CL-BR dye at alkaline pH. It was possible to achieve 98% colour removal with 30 min of ozonation at pH 9. the colour removal of dye was found to follow first order kinetics.

关键词： azo dye bleach wastewater Fenton hydrogen peroxide ozone