Adsorption process has an importance for improving the color of juice and also stabilizing the final product during the shelf life. In this study, polyvinylpolypirrolidone (PVPP) and octadecyl acrylate-co-ethylene glycol dimethacrylate (ODA-EGDMA) polymeric resins were used as adsorbents for improving the color properties of apple juice. The ODA-EGDMA resin was prepared by classical suspension polymerization technique and characterized by electron microscopy. The obtained spherical particles diameters were between 20 and 140 μm. PVPP was selected as reference polymeric material for its importance in the juice industry. The adsorption kinetics of dark-colored compounds on adsorbent polymeric resins were studied at different adsorbent resins concentrations (1, 2, 4, and 8 g adsorbent resin per liter of apple juice) at the constant temperature (20 °C) in batch reactor. Langmuir adsorption model was applied for both PVPP and ODA-EGDMA polymeric adsorbents. The Langmuir isotherms were plotted for both polymeric adsorbents by evaluation of the absorbance data of apple juice at 420 nm. Langmuir isotherm's empirical constants known as Kad and Q0 were calculated from the equilibrium data. Numerical value of Kad and Q0 were determined as 5.0578 and 0.3089 for the ODA-EGDMA polymeric resin, 2.4824 and 0.5268 for the PVPP adsorbent, respectively. The scope of this study included comparison of reusability and regeneration properties of the each polymeric adsorbent. For this purpose, series of experiment were done in pack bed column application. Pressure drop measured throughout the PVPP pack bed column was 4.8 times higher than ODA-EGDMA pack bed column at same flow rate (2.5 mL/min) during the this group experiment. ODA-EGDMA resin and PVPP were regenerated with NaOH (4% w/v, 50 °C) after each run. After regeneration, average removal of dark color (relative absorbance change at 420 nm) of apple juice was determined as 76.47±0.90% for ODA-EGDMA and 91.51±0.86% for PVPP adsorbent resin. 相似文献
In heterogeneous networks where macro cells and metro cells use the same frequency band to communicate with their respective users, the major problem limiting performance is the interference caused by macro cells to metro cells. The information theoretic result known as dirty paper coding provides a way to address this problem and significantly improve the performance of heterogeneous networks with co-channel deployment. In this paper, we show how a simple dirty paper coding scheme employing Tomlinson-Harashima pre-coding with partial interference pre-subtraction can be employed by metro cells to mitigate the interference caused by macro cells. A performance study included in this paper shows that the proposed dirty paper coding scheme can lead to significant improvement in user rate statistics.
The aim of this study is to determine the input–output energy consumption and to make a cost analysis of intermediate type stake-tomato grown in open field in Tokat province of Turkey. The data used in the study were obtained from 98 local tomato growers using a questionnaire. The farms were chosen by random sampling method. The results showed that the amount of energy consumed in stake-tomato production was 96 957.36 MJ ha−1. About 42% of this was generated by diesel oil and 38% from fertilizers and machinery. The input–output ratio was 0.80 and energy productivity was found to be 1.00 kg MJ ha−1. About 76% of the total energy inputs used in stake-tomato production was non-renewable while only about 22% was renewable. These findings reveal that intensive input use in stake-tomato production, especially chemical fertilizers, gives a high tomato yield but also raises some problems like environmental pollution and global warming. Thus, new policies, emphasizing energy consumption without degradation of national resources, should be designed for such farms. 相似文献
Lattice dynamical calculations are performed on Ta-W alloys with bcc structure in various concentrations. We assume ion-ion interaction through the improved third-neighbor Clark-Gazis-Wallis (CGW) model. The theory has been applied to compute the dispersion curves, frequency spectra and lattice specific heat of the studied alloys. The obtained results are in good agreement with the available experimental ones. 相似文献
The main objective is to investigate Turkey's fossil fuels demand, projection and supplies by using the structure of the Turkish industry and economic conditions. This study develops scenarios to analyze fossil fuels consumption and makes future projections based on a genetic algorithm (GA). The models developed in the nonlinear form are applied to the coal, oil and natural gas demand of Turkey. Genetic algorithm demand estimation models (GA-DEM) are developed to estimate the future coal, oil and natural gas demand values based on population, gross national product, import and export figures. It may be concluded that the proposed models can be used as alternative solutions and estimation techniques for the future fossil fuel utilization values of any country. In the study, coal, oil and natural gas consumption of Turkey are projected. Turkish fossil fuel demand is increased dramatically. Especially, coal, oil and natural gas consumption values are estimated to increase almost 2.82, 1.73 and 4.83 times between 2000 and 2020. In the figures GA-DEM results are compared with World Energy Council Turkish National Committee (WECTNC) projections. The observed results indicate that WECTNC overestimates the fossil fuel consumptions. 相似文献
The scattering of electromagnetic waves from a frequency selective surfaces (FSSs) composed of a new two-turn square spiral shaped periodic structures are investigated by using modal expansion method. The moment method of Galerkin type is employed by expressing the current induced on the metallic surfaces in terms of Piecewise Sinusoidal (PWS) basis functions to determine the FSS structure reflection and transmission coefficients. 相似文献
Vacuum cooling is known as a rapid evaporative cooling technique for any porous product which has free water. The aim of this paper is to apply vacuum cooling technique to the cooling of the iceberg lettuce and show the pressure effect on the cooling time and temperature decrease. The results of vacuum cooling are also compared with conventional cooling (cooling in refrigerator) for different temperatures. Vacuum cooling of iceberg lettuce at 0.7 kPa is about 13 times faster than conventional cooling of iceberg lettuce at 6 °C. It has been also found that it is not possible to decrease the iceberg lettuce temperature below 10 °C if vacuum cooling method is used and vacuum pressure is set to 1.5 kPa. 相似文献