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Öğe First boundary value problem for cordes-type semilinear parabolic equation with discontinuous coefficients(Hindawi, 2020-06-19) Harman, Aziz; Harman, EzgiFor a class of semilinear parabolic equations with discontinuous coefficients, the strong solvability of the Dirichlet problem is studied in this paper. The problem ∑i,j=1naijt,xuxixj-ut+gt,x,u=ft,x,uΓQT=0, in QT=Ω×0,T is the subject of our study, where Ω is bounded C2 or a convex subdomain of En+1,ΓQT=∂QT\∖t=T. The function gx,u is assumed to be a Caratheodory function satisfying the growth condition gt,x,u≤b0uq, for b0>0,q∈0,n+1/n-1,n≥2, and leading coefficients satisfy Cordes condition b0>0,q∈0,n+1/n-1,n≥2.Öğe Comparative experimental investigation on the effects of heavy alcohols- safflower biodiesel blends on combustion, performance and emissions in a power generator diesel engine(Elsevier, 2021-02-05) Işık, Mehmet ZerrakkiThe experimental works carried out in this article evaluates the potential of using heavy alcohol and safflower biodiesel as the blended fuel mixtures without making any modifications in the tests diesel engine. For this purpose, volumetrically 20% of Propanol, Pentanol, Butanol, and Octanol were blended with safflower biodiesel fuel and they were named as PR20, PE20, BU20, and OC20, respectively. The performance, combustion, and emission data were found out at the same conditions of constant engine speed and various loads and compared with pure biodiesel (B100) and diesel fuel(ULSD). In the experiments, a four-cylinder, water-cooled diesel engine that was loaded by an electrical power generator was used for the tests. The addition of alcohol causes an increase in fuel consumption due to a decrease in lower thermal performance. The use of heavy alcohols in diesel engine in specific quantities by mixing with biodiesel significantly increases engine brake thermal efficiency. Negative effects of low cetane number and high latent heat of vaporization that may decrease ignition delay and decrease cylinder pressure while increase peak heat release was considered to be compensated by the better mixing properties and atomization of alcohol blended biodiesel thus eventually improve the combustion. Alcohol addition to biodiesel fuel can be accepted as a useful application to increase brake thermal efficiency and reduce nitrogen oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC) emissions by reducing the density and viscosity.Öğe An innovative research on variable compression ratio in RCCI strategyon a power generator diesel engine using CNG-safflower biodiesel(Elsevier, 2021-09-15) Aydın, HüseyinThe CNG usage as a fuel in IC engines have many advantages such as decreasing CO2and PM and smokeemissions and in many cases reducing NOx emission, along with its low prices and naturally abundancespread on the world. In heavy loaded operation of diesel engines, it becomes very hard to controlexcessive NOx, and PM formation in the exhaust emissions and smoke accumulation especially forbiodiesel usage. In the present study, in order to achieve the usability of higher percentages of biodieselwith CNG, the low temperature combustion of reactivity controlled compression ignition (RCCI) strategyhave been applied in a single cylinder diesel engine with variable compression ratios. The CNG, as thelow reactivity fuel, was subjected to the intake manifold as the substitute the gas with 5%, 10% and 15% ofbiodiesel under 1500 rpm and 10.8 kW(full load) load of the engine with variable compression ratiosfrom 13:1 to 19:1 in order to investigate the effects of compression ratios on RCCI operation with highpercentages of biodiesel and CNG usage. Apart from the main performance, emissions and combustionindicators of diesel engines tests, 3 novel parameters (SPE, STE and SHRE) were created for thefirst timein order to deeply evaluate the combustion. Mean of cylinder pressure was increased while combustionduration was lowered for CNG usage with biodiesel. BTE was increased while BSEC and BSFC weredecreased in either operation of biodiesel/CNG RCCI and various CR. In addition, NOx emissions werelowered for CNG usage and CR decrease, along with smoke decrease for biodiesel/CNG RCCI combustion.Öğe Production of mixed rare earth oxide powder from a thorium containing complex Bastnasite ore(Journals & Books, 2021-02) Özsaraç, Şafak; Kurşunoğlu, Sait; Hussaini, Shokrullah; Top, Soner; Ichlas, Zela Tanlega; Gökçen, Hasan Serkan; Kaya, MuammerThe production of mixed rare earth oxide powder from a thorium containing bastnasite ore by sulfuric acid bake-water leaching followed by precipitation with oxalic acid and thermal decomposition of the oxalates was investigated. The sulfuric acid baking was performed at 250 °C and the optimum baking time was found to be 3 h. Using deionized water as lixiviant, 92.6% La, 86.8% Ce, 86.9% Pr, 82.3% Nd, 95.4% Th and 31% Y were dissolved from the baked ore at 25 °C after 30 min of leaching. The effect of solid-to-liquid ratio on the dissolution of the rare earth elements and thorium shows that when the solid ratio in the water increased from 1:10 to 1:3, the dissolution percentage decreased. The final mixed rare earth oxide powder contained 88.54% REO and 6% ThO2 together with small amounts of other impurities. The SEM mapping results revealed that the produced REO has an irregular crystal shape. Based on the experimental results obtained from the current study, a flowsheet was proposed for the production of mixed rare earth oxide powder from a specific complex bastnasite ore.Öğe Correlation formulation for optimum tilt angle for maximizing the solar radiation on solar collector in the Western Himalayan region(Journals & Books, 2021-01) Kallioğlu, Mehmet Ali; Sharma, Ashutosh; Awasthi, Anchal; Chauhan, Ranchan; Fekete, Gusztáv; Singh, TejSolar tracking devices are efficacious in maximizing solar irradiation collection. However, higher price makes these systems less frequently used. As an alternative, optimum tilt angle estimation has the advantage that it does not involve tracking cost expenditure. In this study, optimum tilt angles for different months have been computed for Hamirpur, Himachal Pradesh, India (L 31° 42′ N). Several mathematical models and statistical tools have been employed to forecast the monthly optimum tilt angles for the selected site. Different scenarios have been presented by considering five, four, three, and two annual adjustment models to increase the practical usage of the estimated optimum tilt angles. Additionally, cost-benefit analysis has also be performed on the PV panels. Based on the results, it has been concluded that model M − 11, with three annual adjustments, stipulates maximum benefits over the other models. This study can serve as fundamental guidance for setting up solar energy plants in this specified region with the highest efficiency.
