Assessment of power and hydrogen production performance of an integrated system based on middle-grade geothermal source and solar energy

In this study, power and hydrogen production performance of an integrated system is investigated. The system consists of an organic Rankine cycle (ORC), parabolic trough solar collectors (PTSCs) having a surface area of 545 m², middle-grade geothermal source (MGGS), cooling tower and proton exchange membrane (PEM). The final product of this system is hydrogen that produced via PEM. For this purpose, the fluid temperature of the geothermal source is upgraded by the solar collectors to drive the ORC. To improve the electricity generation efficiency, four working fluids namely n-butane, n-pentane, n-hexane, and cyclohexane are tried in the ORC. The mass flow rate of each working fluid is set as 0.1, 0.2, 0.3, 0.4 kg/s and calculations are made for 16 different situations (four types of working fluids and four different mass flow rates for each). As a result, n-butane with a mass flow rate of 0.4 kg/s is found to be the best option. The average electricity generation is 66.02 kW between the hours of 11⁰⁰-13⁰⁰. The total hydrogen production is 9807.1 g for a day. The energy and exergy efficiency is calculated to be 5.85% and 8.27%, respectively.     

Optical dispersion and dielectric properties of rubrene organic semiconductor thin film

Rubrene thin film has been fabricated on a glass substrate by spin-coating at 300 K. The optical dispersion and dielectric properties of the film have been determined from the analysis of transmittance and reflectance measurements at normal incident of light between 200 and 700 nm. The optical transmittance of the film was estimated as of 80–85 % in the visible range. Optical absorption characteristics show that the absorption mechanism is due to the indirect transition. The transport and onset optical energy gaps were determined as 2.93 and 2.31 eV, respectively. Single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model were used to determine the optical dispersion parameters. Several dispersion parameters such as lattice dielectric constant, optical dielectric constant at higher frequency, dispersion energy, oscillator energy, the ratio of carrier concentration to the effective mass, the average oscillator wavelength, and average oscillator strength were determined by analysis of refractive index dispersion. The loss factor, the electric modulus, the optical conductivity, the volume and surface energy loss functions, and the relaxation time were also evaluated from the optical dielectric constants analysis.     

Robust crew pairing for managing extra flights

This paper discusses a modeling approach to robust crew pairing when a set of extra flights is likely to be added to the regular flight schedule. The set of these possible extra flights is known at the planning stage. We demonstrate that these extra flights may be incorporated into the schedule if necessary by modifying the planned crew pairings appropriately and without delaying or canceling existing flights. To this end, we either identify a pair of crews whose schedules may be (partially) swapped while adding an extra flight into the schedule or show that an extra flight may be inserted into the schedule of a crew without affecting others. We note that deadheading may be necessary in either case. For these two types of solutions, we define the appropriate feasibility rules with respect to the common airline regulations. We then propose two robust mathematical programming models that consider incorporating such solutions into the set of selected pairings while keeping the increase in the crew cost at an acceptable level. The baseline solution for comparison is found by a conventional crew pairing model in the literature which ignores robustness at the planning stage and relies on recovery procedures at the time of operation. We also propose the variations of the two models, where the double counting of the possible solutions across extra flights is prevented. Finally, we conduct computational experiments on a set of data generated from the actual data of an airline company. We solve the crew pairing problem both with the proposed robust models and the conventional model. Our results demonstrate the benefits of the proposed modeling approach and indicate that the proposed robust models provide natural options to recovery without disrupting the existing flights at a relatively small incremental cost, which is visible at the planning stage.     

Extracellular Pectinase Production and Purification from a Newly Isolated Bacillus subtilis Strain

Pectinase is widely used in the fruit juice industry with various aspects, especially to reduce blur in fruit juice. To produce pectinase, Bacillus subtilis were isolated from Kilis soil contaminated by agricultural crop wastes. The extracellular pectinase was purified by using three different technics (cell-free supernatant, ethanol, and ammonium sulphate precipitation) and enzyme activity was measured with spectrophotometric analysis. The maximum specific activity was observed in enzyme preparate purified by ethanol precipitation, 217.44 U/mg. The degradation products of reaction–glucose, saccharose, and fructose–were identified by Fourier transform infrared spectroscopy and thin layer chromatography analysis. Two protein bands belong to pectinase of B. subtilis were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Molecular weights of bands were approximately calculated as 60 and 64 kDa.     

Optical and electrical properties of new organic thin film

This paper describes a new organic thin film (OTF) (50 nm) which was deposited by spin coated at room temperature. OTF has been constructed from chemically synthesized poly(pentachlorophenyl methacrylate-co-glycidyl methacrylate). Optical properties of the obtained poly(pentachlorophenyl methacrylate-co-glycidyl methacrylate) in solution were tested by ultraviolet–visible absorption spectroscopy. The analysis of the optical absorption data revealed an existence of a direct and indirect transition optical band gap (E_g). The electrical properties of ITO/PEDOT:PSS/OTF/Al heterojunction structure has been investigated by forward and reverse bias current–voltage (I–V) measurements at room temperature. The main electrical parameters such as barrier height (Φ_Bo), ideality factor (n) and reverse saturation current (I_o) have been calculated by applying thermionic emission theory as 0.80 eV, 3.69, 1.86 × 10^?8 A respectively. Additionally, series resistance (R_s), Φ_Bo and n were calculated from the forward bias I–V data using the methods of Cheung and Cheung with Norde and showed that these methods can be applied successfully for this structure.     

Effect of cultivation area and climatic conditions on volatiles of virgin olive oil

To elucidate the influence of the cultivation area and climatic conditions on volatiles of virgin olive oil from Gemlik cultivar, an investigation was carried out. Five Turkish geographical zones (Bal?kesir, Ayd?n, Manisa, Antalya and Hatay) were chosen. From these areas, fruits were collected at the same maturity stage and processed using a small experimental olive oil mill, applying identical processing conditions for all olive samples. Headspace solid‐phase microextraction (HS‐SPME) technique coupled to GC/MS was used for volatile analysis. Twenty‐seven compounds were identified and characterised, representing 96.40–98.74% of the total GC area. The major volatile representing about 50% was the (E)‐2‐hexenal. This compound was found in higher concentrations on olive oils from Antalya than from Hatay area. Hexanal was the second most abundant volatile compound and varied between 13.89 and 28.96%. Comparing the olive growing areas Hatay and Antalya, the hexanal concentration was about 29 and 14%, respectively. Generally, a significant difference in the composition of volatile compounds between the oils from the same olive cultivar and from different geographic regions was recorded. The results suggest that climatic factors, latitude and longitude affect the formation of volatiles.