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Compression properties of cost-efficient porous expanded clay reinforced AA7075 syntactic foams fabricated by industrial-oriented die casting technology

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China Foundry 2024年第1期21卷 60-70页

作者： İsmail cem Akgün Çağın Bolat Ali Gökşenli Faculty of Mechanical Engineering Istanbul Technical University34437İstanbulTurkey Faculty of Engineering Samsun University55420SamsunTurkey

In today’s manufacturing industries,hard competition between rival firms makes it compulsory for researchers to design lighter and cheaper machine components due to the megatrends of cost-effectiveness and *** this point,aluminum syntactic foams(ASFs)are new-generation engineering composites and come into the upfront as a *** to their features like low density,sufficient elongation,and perfect energy absorption ability,these advanced foams have been considerably seductive for many industrial sectors *** this study,an industrial-oriented automatic die casting technology was used for the first time to manufacture the combination of AA7075/porous expanded clay(PEC).Micro evaluations(optical and FESEM)reveal that there is a homogenous particle distribution in the foam samples,and inspections are compatible with the other ASF ***,T6 aging heat treatment was operated on one half of the produced foams to explore the probable impact of aging on the compressive *** results show that PEC particles can be an alternative to expensive hollow spheres used in the previous ***,a favorable relationship is ascertained between the aging treatment and mechanical properties such as compression strength and plateau strength.

关键词： die casting porous materials metal matrix sytanctic foams expanded clay compressive deformation

Effects of particle size,bimodality and heat treatment on mechanical properties of pumice reinforced aluminum syntactic foams produced by cold chamber die casting

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China Foundry 2021年第6期18卷 529-540页

作者： Cagin Bolat Ismail cem Akgun Ali Goksenli Faculty of Mechanical Engineering Istanbul Technical University34437IstanbulTurkey

In recent years,metal matrix syntactic foams(MMSFs)have become highly attractive owing to their unique physical,microstructural and mechanical *** to their promising potential for different industrial areas like automotive,aviation,and defense,these advanced engineering materials can also be evaluated as serious alternatives to particle reinforced metallic composites and conventional metallic *** from previously reported laboratory scaled techniques in the literature,this experimental effort focuses on the feasibility of MMSF manufacturing via a fully automated and industrial-based cold chamber die casting ***,1-2 mm,2-4 mm,and bimodal(50vol.%)natural-based pumice filled aluminum syntactic foams were manufactured utilizing a purpose-made casting ***,macroscopic,and microscopic examinations show that all of the fabricated samples display perfect matrix/filler *** density levels of fabricated syntactic foams range between 1.50 and 1.80 g·cm^(-3) depending upon the pumice particles size *** assess mechanical responses,quasi-static compression tests were ***,half of the foam samples were subjected to heat treatment to explore possible influences of aging on the compressive features and damage *** indicate that although the heat treatment enhances the compressive strength,plateau stress,and energy absorption properties of the fabricated foams,it changes damage mode of the samples by causing brittle dominant deformation.

关键词： pumice cold chamber die casting syntactic foam bimodality damage characteristic

Invisible face of COVID-19 pandemic on the freshwater environment:An impact assessment on the sediment quality of a cross boundary river basin in Turkey

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International Journal of Sediment Research 2022年第2期37卷 139-150页

作者： cem Tokatl? Laboratory Technology Department Evrenos Gazi Campus Trakya University

In the current research,the impact of the COVID-19 lockdown period on sediment quality of the MericErgene River Basin was evaluated by determining the potentially toxic elements(PTEs) in sediment samples collected from 25 sampling points in the *** some important ecological indicators including potential ecological risk index(PERI),contamination factor(CF),pollution load index(PLI),biological risk index(BRI),and geo-accumulation index(I) and some important statistical indicators including the Pearson correlation index(PCI),factor analysis(FA),and cluster analysis(CA) were applied to collected *** of all the investigated PTEs in sediment of the basin show significant differences between the pre-lockdown and lockdown *** PTE contents have considerably decreased by12.8%-45.4% during the lockdown ***,the results of applied sediment quality risk assessment indices showed significant improvement and the values have decreased by 22.4%-35.8%.In the lockdown period,reduction of industrial activities or limited production at many industrial facilities located in the basin reduced the amount of effluent,leading to significant improvement in sediment quality.

关键词： Meric-Ergene River basin Sediment quality Ecological-statistical indicators COVID-19 pandemic Lockdown period

Learning distance effect on lignite quality variables at global and local scales

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International Journal of Coal Science & Technology 2021年第5期8卷 856-868页

作者： cem Yaylagul Bulent Tutmez Dodurga Control Directorate Turkish Coal Enterprises(TKI)CorumTurkey Department of Mining Engineering Inonu UniversityMalatyaTurkey

Determining scale and variable effects have critical importance in developing an energy resource *** study aims to explore the relationships in heterogeneous lignite sites using different scale models,spatial weighting as well as error-based pair-wise *** a statistical learning framework,the relationships among the quality variables such as geochemical variables and the contributions of the coordinates to quality measures have been exhibited by generalized additive *** this way,the critical roles of spatial weights provided by the coordinates have been specified at a global *** experimental studies reveal that incorporating the geological weighting in the models as the additional information improves both accuracy and *** relationships among lignite quality variables and sampling locations are spatially non-stationary,the local structure and interdependencies among the variables were analyzed by geographically weighting *** local analyses including spatial patterns of bandwidths,search domains as well as residual-based areal dependencies provided not only the critical zones but also availability of pair-wise model alternatives by calibrating a model at each point for location-specific parameter *** results completely show that the weighting models applied at different scales can take spatial heterogeneity into consideration and these abilities provide some meta-data and specific information using in sustainable energy planning.

关键词： Lignite Distance effect Exploration Generalized Additive Model(GAM) Geographically Weighted Regression(GWR)

Improved population mean estimator with exponential function under non-response

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Applied Mathematics(A Journal of Chinese Universities) 2023年第4期38卷 562-580页

作者： CerenUnal cem Kadilar Department of Statistics Hacettepe UniversityAnkara 06800Turkey

In this article,we consider a new family of exponential type estimators for estimating the unknown population mean of the study *** propose estimators taking advantage of the auxiliary variable information under the first and second non-response cases *** required theoretical comparisons are obtained and the numerical studies are *** conclusion,the results show that the proposed family of estimators is the most efficient estimator with respect to the estimators in literature under the obtained conditions for both cases.

关键词： non-response exponential estimators sub-sampling method population mean

Computer controlled measurement of spontaneous combustion in coal stockpiles of the Western Lignite Corporation, Turkey

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Journal of University of Science and Technology Beijing 2006年第2期13卷 97-101页

作者： A. Hadi Ozdeniz cem Sensogut Mining Engineering Department Selcuk University 42079 Konya Turkey Mining Engineering Department Dumlupinar University 43100 Kutahya Turkey

The spontaneous combustion event in coal stockpiles is inevitable when appropriate environmental conditions are available. The objective of a computerized measurement system is to measure temperature changes existing in a coal stockpile. In order to achieve this intention, the electrical signal conversion of temperatures sensed by 20 temperature sensors placed in certain points inside the coal stockpile, the transfer of these electrical signals into computer media by using analogue-digital conversion unit after applying necessary filterization and upgrading processes and the record of these information into a database in particular time intervals are provided. Afterwards, the diagrams of these time-temperature data are plotted. With the help of these graphs, the competent company will be able to examine the behavior of coal stockpiles in terms of spontaneous combustion and take necessary precautions against self-combustion beforehand.

关键词： spontaneous combustion coal stockpile Western Lignite Corporation resistance temperature detector

Prediction of Excess Air Factor in Automatic Feed Coal Burners by Processing of Flame Images

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Chinese Journal of Mechanical Engineering 2017年第3期30卷 722-731页

作者： Muhammed Fatih TALU cem OnAT Mahmut DASKIn computer engineering department inonu university44280 MalatyaTurkey mechanical engineering department inonu university44280 MalatyaTurkey

In this study, the relationship between the visual information gathered from the flame images and the excess air factor 2 in coal burners is investigated. In conventional coal burners the excess air factor 2. can be obtained using very expensive air measurement instruments. The proposed method to predict ） for a specific time in the coal burners consists of three distinct and consecutive stages; a） online flame images acquisition using a CCD camera, b） extrac- tion meaningful information （flame intensity and bright- ness）from flame images, and c） learning these information （image features） with Anns and estimate 2. Six different feature extraction methods have been used： CDF of Blue Channel, Co-Occurrence Matrix, L-Frobenius norms, Radiant Energy Signal （RES）, PCA and Wavelet. When compared prediction results, it has seen that the use of co- occurrence matrix with Anns has the best performance （RMSE = 0.07） in terms of accuracy. The results show that the proposed predicting system using flame images can be preferred instead of using expensive devices to measure excess air factor in during combustion.

关键词： Excess air factor Flame images Coal burner

A new Privacy-Preserving Data Publishing Algorithm Utilizing Connectivity-Based Outlier Factor and Mondrian Techniques

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Computers, Materials & Continua 2023年第8期76卷 1515-1535页

作者： Burak cem Kara Can Eyüpoglu Department of Computer Engineering Turkish Air Force AcademyNational Defence UniversityYesilyurtIstanbulTurkey Department of Computer Engineering Atatürk Strategic Studies and Graduate InstituteNational Defence UniversityBesiktasIstanbulTurkey

Developing a privacy-preserving data publishing algorithm that stops individuals from disclosing their identities while not ignoring data utility remains an important goal to *** finding the trade-off between data privacy and data utility is an nP-hard problem and also a current research *** existing approaches are investigated,one of the most significant difficulties discovered is the presence of outlier data in the *** data has a negative impact on data ***,k-anonymity algorithms,which are commonly used in the literature,do not provide adequate protection against outlier *** this study,a new data anonymization algorithm is devised and tested for boosting data utility by incorporating an outlier data detection mechanism into the Mondrian *** connectivity-based outlier factor(COF)algorithm is used to detect *** is selected because of its capacity to anonymize multidimensional data while meeting the needs of real-world ***,on the other hand,is used to discover outliers in high-dimensional datasets with complicated *** proposed algorithm generates more equivalence classes than the Mondrian algorithm and provides greater data utility than previous algorithms based on *** addition,it outperforms other algorithms in the discernibility metric(DM),normalized average equivalence class size(Cavg),global certainty penalty(GCP),query error rate,classification accuracy(CA),and F-measure ***,the increase in the values of theGCPand error ratemetrics demonstrates that the proposed algorithm facilitates obtaining higher data utility by grouping closer data points when compared to other algorithms.

关键词： Data anonymization privacy-preserving data publishing k-anonymity generalization mondrian

Microstructure and hardness of Mg-based composites reinforced with Mg_2Si particles

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Rare Metals 2009年第4期28卷 396-400页

作者： Mustafa Aydin cem zgür Osman San Mechanical Engineering Department Dumlupinar University Ceramic Engineering Department Dumlupinar University

Magnesium powders were mechanically alloyed with SiO2 powder particles having different particle sizes using nigh-energy ball milling techniques under Ar atmosphere for 1 h. The powders were consolidated with cold pressing under 560 MPa. They were then sintered at 550℃ for 45 min under Ar atmosphere. The composites obtained on the Mg-SiO2 system were investigated using the Archimedes principle, a differential scanning calorimeter, X-ray diffraction, optic microscopy, and scanning electron microscopy. For the mechanically alloyed powders, the solid-state reaction of the synthesis of Mg2Si and MgO progressed further during sintering of the materials. The results showed that the strengthening mechanisms were dependent on dispersion hardening of fine Mg2Si and MgO particulates dispersed homogeneously in the matrix. Mg-

关键词： based composites SiO2 mechanical alloying strengthening mechanism