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Thinning effects on biomass and element concentrations of roots in adjacent hornbeam and oak stands in Istanbul,Turkey

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Forest Ecosystems 2021年第1期8卷 1-10页

作者： serdar Akburak Ender Makineci Faculty of Forestry Soil Science and Ecology DepartmentIstanbul University-Cerrahpasa34473 BahcekoySariyerIstanbulTurkey

Background:Thinning is a commonly used treatment in forest management which affects the tree root *** effects of thinning on element concentrations and seasonal change of roots were evaluated in adjacent oak(Quercus frainetto Ten.)and hornbeam(Carpinus betulus L.)stands according to the different root diameter ***:Two replicated control and thinning plots(50m×50 m)were set for each species(hornbeam and oak).Thinning treatments(November 2010)reduced 50%of the basal area in both oak and hornbeam *** were assessed by seasonal collection over 2 years(from October 2010 to October 2012).The roots were then sorted into diameter classes of 0–2mm(fine roots),2–5mm(small roots)and>5mm(coarse roots).C,N,P,K,Ca,Na,Mg,S,Mn,Fe,Al,Zn,Pb,Ni,Cu and Cd were ***:Except coarse roots,the highest root biomasses were determined in April-2011 in all ***-root biomass in oak was found significantly higher in control *** contrast to the oak,the fine-root biomass in the thinned hornbeam plots was higher than in the *** small-root biomass did not significantly differ between the thinned and the control plots in both oak and hornbeam ***,the coarse-root biomass showed significant differences between the control(1989 g∙m^(−2))and thinned plots(1060 g∙m^(−2))in oak,while no difference was detected in *** concentrations of C,Al,Pb,Cd,Ni,Zn,Mn,Na,K,Mg and P in the fine roots of oak were significantly higher in the thinned ***,the concentration of Pb,Cd and Fe in the fine roots was significantly higher in the thinned plots of *** differences were observed between the species for all elements in the fine roots except for C,N and *** particular,elements in the fine roots tended to increase in July in the *** the hornbeam,all element concentrations in the fine roots(except C,N,and S)in the thinned plots showed a tendency to increase in *** concentrations of Pb,Ni,Al,Fe,Cu,Ca,Na,K,Mg and

关键词： Carpinus Coarse root Fine root Quercus Small root

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An integrated approach to assess the ecological and chemical status of lakes with HOD/AHOD: a case study of two lakes

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Journal of Oceanology and Limnology 2019年第1期37卷 146-159页

作者： serdar GONCü Erdem ALBEK Anadolu University Ikieylul Campus Environmental Eng.Dept.

The thermal strati?cation of the lakes impedes the transfer of atmospheric oxygen into the lower layers of the lake. In lakes which are af fected by diverse anthropogenic in?uences, the increasing organic matter amounts lead to a sharp decrease in hypolimnetic oxygen amounts, aided by thermal strati?cation,and anaerobic conditions arise. The determination of hypolimnetic oxygen demand(HOD) and areal hypolimnetic oxygen demand(AHOD) and their monitoring represent an integrated approach to investigate the oxygenation of lakes, the nutrient conditions, and the physicochemical dynamics. In this study, two lakes dif fering by size and af fected by dif ferent anthropogenic sources, are investigated in this respect. At?rst, bathymetric studies were conducted to determine the depth, surface area, and volume ***, based on monitoring studies conducted in 2013 and 2014, the thermal strati?cation dynamics and layer properties were established using the relative thermal resistance to mixing(RTRM) index based on temperature and density pro?les. Following this, the oxygen depletion rates were determined by oxygen and temperature pro?ling in the hypolimnion. For the years of 2013 and 2014, the AHOD values for the Borabey Pond which is far from anthropogenic in?uences, were found to be 0.848 and 0.569 g O 2/(m·d), *** AHOD values for the Porsuk Reservoir which was overburdened for years by industrial and domestic pollution were found to be 4.263 and 5.099 g O 2/(m·d), larger than its counterpart by almost sevenfold. The HOD and AHOD monitoring can be considered to a valuable tool for assessing the ecological and chemical status of lakes within Annex 5 of the Water Framework Directive and as an integrated approach to assess and monitor the status of lakes.

关键词： hypolimnetic oxygen demand(HOD) areal hypolimnetic oxygen demand(AHOD) thermal stratifcation relative thermal resistance to mixing(RTRM) Borabey Pond Porsuk Dam

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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

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Determination and evaluation of biogas and methane productions of vegetable and fruit wastes with Hohenheim Batch Test method

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International Journal of Agricultural and Biological Engineering 2017年第4期10卷 207-215页

作者： Ali Aybek serdar Üçok Faculty of Agriculture Department of Biosystems EngineeringKahramanmarasSutcu Imam UniversityKahramanmarasTurkey

Nowadays,biogas technology applications are gradually increasing worldwide due to the economic and environmental *** researches and studies related to the determination of the biogas potential of organic waste materials have been carried out in the recent *** to determine the specific methane potential of organic waste materials have a great importance for both design and economical operation of the biogas *** potential that will be recovered from organic wastes is substantial in *** to biogas plants gathering vegetable-fruit wastes and other organic wastes are planned to produce significant amount of renewable energy in Turkish *** to the use of organic wastes,the disposal of waste as well as energy production,soil,water and air pollution in terms of environmental protection are also *** the other hand,the organic wastes produced from plants can also be utilized as fertilizer in vegetable *** this study,the cumulative biogas and methane production of vegetable and fruit wastes were experimentally determined with HBT(Hohenheim Batch Test)*** and methane yields of vegetable and fruit wastes were found as 0.54-0.73 Nm^(3)/(kg ODM)and 0.29-0.37 Nm^(3)/(kg ODM),*** highest value of the cumulative specific methane production was tomato wastes(0.37 Nm^(3)/(kg ODM)),and the lowest value was lettuce wastes(0.29 Nm^(3)/(kg ODM)),as *** average cumulative specific methane production values of mixed vegetable and fruit wastes are determined as 0.34 Nm^(3)/(kg ODM).

关键词： biogas methane production Hohenheim Batch Test vegetable and fruit wastes renewable energy Turkey

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Seepage failure by heave in sheeted excavation pits constructed in stratified cohesionless soils

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Frontiers of Structural and Civil Engineering 2019年第6期13卷 1415-1431页

作者： serdar KOLTUK Jie SONG Recep IYISAN Rafig AZZAM HPC AG Stuttgart 70597Germany Department of Engineering Geology and Hydrogeology RWTH Aachen UniversityAachen D-52064Germany Civil Engineering Faculty Istanbul Technical UniversityIstanbul 34646Turkey

In this study,experimental and numerical investigations are performed to clarify the seepage failure by heave in sheeted excavation pits in stratified cohesionless soils in which a relatively permeable soil layer(Kupper)lies above a less permeable soil layer(Klower)between excavation base and wall *** is shown that the evaluation of base stabilities of excavation pits against seepage failure by using Terzaghi and Peck's approach leads to considerably lower critical potential differences than those obtained from the model *** the other hand,a relatively good agreement is achieved between the results of the model tests and the finite element(FE)*** investigations are performed by using axisymmetric excavation models with various dimensions and ground conditions,and a comparison between the results obtained from Terzaghi and Peck's approach and finite element analyses is given.

关键词： seepage failure by heave cohesionless stratified soil model test Terzaghi and Peck's approach FE analysis

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Linearity extensions of the market model:a case of the top 10 cryptocurrency prices during the pre‑COVID‑19 and COVID‑19 periods

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Financial Innovation 2021年第1期7卷 799-825页

作者： serdar Neslihanoglu Department of Economics and NIPE University of MinhoBragaPortugal Department of Statistics Faculty of Science and LettersEskisehir Osmangazi UniversityEskisehirTurkey

This research investigates the appropriateness of the linear specification of the market model for modeling and forecasting the cryptocurrency prices during the pre-COVID-19 and COVID-19 *** extensions are offered to compare the performance of the linear specification of the market model(LMM),which allows for the measurement of the cryptocurrency price beta *** first is the generalized additive model,which permits flexibility in the rigid shape of the linearity of the *** second is the time-varying linearity specification of the LMM(Tv-LMM),which is based on the state space model form via the Kalman filter,allowing for the measurement of the time-varying beta risk of the cryptocurrency *** analysis is performed using daily data from both time periods on the top 10 cryptocurrencies by adjusted market capitalization,using the Crypto Currency Index 30(CCI30)as a market proxy and 1-day and 7-day forward *** a comparison of cryptocurrency prices has yet to be undertaken in the *** empirical findings favor the Tv-LMM,which outperforms the others in terms of modeling and forecasting *** result suggests that the relationship between each cryptocurrency price and the CCI30 index should be locally instead of globally linear,especially during the COVID-19 period.

关键词： CAPM COVID-19 Crypto Currency Index 30 Generalized additive model Kalman filter

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Problems of Syrdarya river basin management

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Frontiers of Environmental Science & Engineering 2009年第2期3卷 221-225页

作者： serdar EYEBERENOV Baijing CAO Fengting LI UNEP-TONGJI Institute of Environment for Sustainable Development Tongji UniversityShanghai 200092China

Prior to independence,Central Asian countries were closely interconnected through the regional management incorporating water,energy,and food *** approach,supported by the central government of Union of Soviet Socialist Republics(USSR),functioned effectively–meeting the needs of both upstream and downstream ***,after independence,Central Asian countries started prioritizing their own economic development policies without due account to regional concerns such as joint use of water resources,leading to *** this study,the case of Syrdarya basin was investigated to show how such strategies create tension in the region,since primary focus is given to national interests,without consideration for regional *** address this issue,an integrated approach to incorporating water,energy,and agriculture is *** is suggested that a single sector approach on water alone does not lead to stability,and a multi-sectoral approach is necessary to ensure sustainable *** sharing benefits from the river have to be responsible for costs of operation and maintenance of the water facilities.

关键词： Central Asia energy agriculture water Syrdarya basin

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Statistical analysis of geomagnetic field variations during the partial solar eclipse on 2011 January 4 in Turkey

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Research in Astronomy and Astrophysics 2015年第5期15卷 742-752页

作者： Abdullah Ates Yunus Levent ekinci Aydin Buyuksarac Attila Aydemir Alper Demirci Ankara University Faculty of Engineering Department of Geophysical Engineering BesevlerTR-06100 Ankara Turkey Bitlis Eren University Faculty of Arts and Sciences Department of Archaeology TR-13000Bitlis Turkey Bitlis Eren University Faculty of Engineering and Architecture Department of Civil Engineering TR-13000 Bitlis Turkey Turkish Petroleum Corp. Sogutozu Mah. 2180. Cad. No: 10 Sogutozu TR-06100 AnkaraTurkey Bitlis Eren University Faculty of Engineering and Architecture Department of Geophysical Engineering TR-13000 Bitlis Turkey

Some geophysical parameters, such as those related to gravitation and the geomagnetic field, could change during solar eclipses. In order to observe geomagnetic fluctuations, geomagnetic measurements were carded out in a limited time frame during the partial solar eclipse that occurred on 2011 January 4 and was observed in Canakkale and Ankara, Turkey. Additionally, records of the geomagnetic field spanning 24 hours, obtained from another observatory （in Iznik, Turkey）, were also analyzed to check for any peculiar variations. In the data processing stage, a polynomial fit, following the application of a running average routine, was applied to the geomagnetic field data sets. Geomagnetic field data sets indicated there was a characteristic decrease at the beginning of the solar eclipse and this decrease can be well-correlated with previous geomagnetic field measurements that were taken during the total solar eclipse that was observed in Turkey on 2006 March 29. The behavior of the geomagnetic field is also consistent with previous observations in the literature. As a result of these analyses, it can be suggested that eclipses can cause a shielding effect on the geomagnetic field of the Earth.

关键词： Sun magnetic field -- eclipses -- methods data analysis -- methods statistics

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Impact of different sampling rates on precise point positioning performance using online processing service

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Geo-Spatial Information Science 2021年第2期24卷 302-312,I0008页

作者： serdar Erol Reha Metin Alkan İ.Murat Ozulu Veli Ilçi Department of Geomatics Engineering Istanbul Technical UniversityIstanbulTurkey Department of Technical Programs Hitit UniversityÇorumTurkey Department of Geomatics Engineering Ondokuz Mayıs UniversitySamsunTurkey

In this study,the effect of different sampling rates(*** recording interval)on the Precise Point Positioning(PPP)solutions in terms of accuracy was *** this purpose,a field test was carried out inÇorum province,Turkey,on 11 September *** this context,a Geodetic Point(GP)was established and precisely coordinated.A static GNSS measurement was occupied on the GP for about 4-hour time at 0.10 second(s)/10 Hz measurement intervals with the Trimble R10 geodetic grade GNSS *** original observation file was converted to RINEX format and then decimated into the different data sampling rates as 0.2 s,0.5 s,1 s,5 s,10 s,30 s,60 s,and 120 *** these RINEX observation files were submitted to the Canadian Spatial Reference System-Precise Point Positioning(CSRS-PPP)online processing service the day after the data collection date by choosing both static and kinematic processing *** this way,PPP-derived static coordinates,and the kinematic coordinates of each measurement epoch were *** PPP-derived coordinates obtained from each decimated sampling intervals were compared to known coordinates of the GP for northing,easting,2D position,and height *** to the static and kinematic processing results,high data sampling rates did not change the PPP solutions in terms of accuracy when compared to the results obtained using lower sampling *** results of this study imply that it was not necessary to collect GNSS data with high-rate intervals for many surveying projects requiring cm-level accuracy.

关键词： Precise Point Positioning(PPP) online GNSS postprocessing service high-rate GNSS sampling rate monitoring structure behavior

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Treatment of retinopathy of prematurity: a review of conventional and promising new therapeutic options

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International Journal of Ophthalmology(English edition) 2013年第2期6卷 228-236页

作者： Fatih Mehmet Mutlu Umit serdar Sarici Department of Ophthalmology Gülhane Military Medical Academy and Medical School Department of Pediatrics Division of Neonatology Gülhane Military Medical Academy and Medical School

Retinopathy of prematurity (ROP), a retinal vascular disease of premature infants, continues to be a major cause of preventable childhood blindness all over the world. The incidence of ROP varies among countries, being influenced by the quality of the level of neonatal intensive care. Here, we discuss the potential treatments that are now available or will soon or probably be available for ROP. Although ablation of the avascular retina with laser photocoagulation remains the current gold standard and well established therapy for ROP, some new therapeutic options including angiostatic therapies are being explored based on our knowledge of the pathophysiology of the ROP and complications and efficacy of laser treatment. However, prevention of the development of severe ROP and screening for ROP seem to be the best strategy in avoiding visual impairment caused by ROP in premature infants. New therapeutic interventions including vascular endothelial growth factor antibody administration, gene therapy and supplemental therapies should be supported with evidence-based data for the treatment of ROP.

关键词： retinopathy of prematurity laser retina vascular endothelial growth factor propranolol

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