Condenser Optimization in Steam Power Plant

In this paper the effects of the condenser design parameters (such as turbine inlet condition, turbine power and condenser pressure) on heat transfer area, cooling water flow-rate, condenser cost and specific energy generation cost are studied for surface type condenser. The results are given in the text and also shown as diagrams.     

Free Vibration Analysis and Design of an Adhesively Bonded Corner Joint with Double Support

This study carries out the three dimensional free vibration analysis of an adhesively bonded corner joint and investigates the effect of an additional horizontal support to the adhesive corner joint with single support on the first ten natural frequencies and mode shapes. In the presence of a horizontal support the effects of the vertical support length, the adhesive thickness, the plate thickness, and the joint length on the natural frequencies and modal strain energies of the adhesive joint were also investigated using the back-propagation Artificial Neural Network (ANN) method and the finite element method. The natural frequencies and modal strain energies increased with increasing plate thickness, whereas an adverse effect was observed for increasing joint length. Both horizontal and vertical support lengths exhibited similar effects but the adhesive thickness had a negligible effect. The plate thickness and the joint length are dominant geometrical parameters in comparison with both horizontal and vertical support lengths. The proposed ANN models were combined with the Genetic Algorithm in order to determine the optimal corner joint in which the maximum natural frequency and minimum elastic modal strain energy are achieved for each natural frequency and mode shape of the adhesive corner joint and the optimal dimensions were given versus one geometrical parameter.     

Vertically aligned carbon nanotube – Polyaniline nanocomposite supercapacitor electrodes

We develop a fast and cost effective method for the fabrication of a nanocomposite supercapacitor electrode. In this study aluminum foils were decorated with vertically aligned carbon nanotubes (VACNT) via chemical vapor deposition (CVD) method, which was followed by the electrodeposition of polyaniline (PANI) layer on top of the VACNTs. Electrochemical behavior of the fabricated nanocomposite electrodes were evaluated through cyclic voltammetry, galvanostatic charge discharge cycles and electrochemical impedance spectroscopy method. Fabricated VACNT/PANI nanocomposite electrodes through 15 electrodeposition cycles showed significant electrochemical performance. The specific capacity of these electrodes was calculated as 16.17 mF/cm² at a current density of 0.25 mA/cm².     

Cellular Biocatalysts Using Synthetic Genetic Circuits for Prolonged and Durable Enzymatic Activity

Cellular biocatalysts hold great promise for the synthesis of difficult to achieve compounds, such as complex active molecules. Whole-cell biocatalysts can be programmed through genetic circuits to be more efficient, but they suffer from low stability. The catalytic activity of whole cells decays under stressful conditions, such as prolonged incubation times or high temperatures. In nature, microbial communities cope with these conditions by forming biofilm structures. In this study, it is shown that the use of biofilm structures can enhance the stability of whole-cell biocatalysts. We employed two different strategies to increase the stability of whole-cell catalysts and decrease their susceptibility to high temperature. In the first approach, the formation of a biofilm structure is induced by controlling the expression of one of the curli component, CsgA. The alkaline phosphatase (ALP) enzyme was used to monitor the catalytic activity of cells in the biofilm structure. In the second approach, the ALP enzyme was fused to the CsgA curli fiber subunit to utilize the protective properties of the biofilm on enzyme biofilms. Furthermore, an AND logic gate is introduced between the expression of CsgA and ALP by toehold RNA switches and recombinases to enable logical programming of the whole-cell catalyst for biofilm formation and catalytic action with different tools. The study presents viable approaches to engineer a platform for biocatalysis processes.     

Bofy-fuzzy logic control for the basic oxygen furnace (BOF)

In this paper, fuzzy modeling for the control of basic oxygen furnace (BOF) processes is proposed. BOF is a widely preferred and effective steel making method due to its higher productivity and considerably low production cost. Therefore, today almost 65% of the total crude steel production in the world is met by using the BOF method. Higher steel output at lower cost is one of the main objectives of modern steel making methods. In order to accomplish this objective, fuzzy modeling was employed in this study in order to control some variables related to the BOF process. Fuzzy modeling and control in BOF promise a solution to the strongly non-linear problems associated with the process, which have so far proven extremely difficult to be solved by conventional control methods. Data set was selected as inputs from the real empirical BOF data in an integrated steel plant based in Turkey. Although there were negligible deviations from the target values, most of the fuzzy results obtained using MATLAB-Fuzzy Logic Toolbox version 5.0 were found to be acceptable. As a result of the application of the proposed modeling, acceptable levels of compatibility were achieved compared to the empirical BOF data and targeted steel composition. The paper indicates how fuzzy logic would be effectively used for improved process control of BOF furnace in steel making industry.     

Adsorptive features of polyacrylamide-apatite composite for Pb2+, UO(2)2+ and Th4+

Micro-composite of polyacrylamide (PAA) and apatite (Apt) was prepared by direct polymerization of acrylamide in a suspension of Apt and characterized by means of FT-IR, XRD, SEM and BET analysis. The adsorptive features of PAA-Apt and Apt were then investigated for Pb(2+), UO(2)(2+) and Th(4+) in view of dependency on ion concentration, temperature, kinetics, ion selectivity and reusability. Experimentally obtained isotherms were evaluated with reference to Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. Apt in PAA-Apt had higher adsorption capacity (0.81, 1.27 and 0.69 mol kg(-1)) than bare Apt (0.28, 0.41 and 1.33 mol kg(-1)) for Pb(2+) and Th(4+), but not for UO(2)(2+). The affinity to PAA-Apt increased for Pb(2+) and UO(2)(2+) but not changed for Th(4+). The values of enthalpy and entropy changed were positive for all ions for both Apt and PAA-Apt. Free enthalpy change was DeltaG<0. Well compatibility of adsorption kinetics to the pseudo-second-order model predicated that the rate-controlling step was a chemical sorption. This was consistent with the free energy values derived from DR model. The reusability tests for Pb(2+) for five uses proved that the composite was reusable to provide a mean adsorption of 53.2+/-0.7% from 4x10(-3)M Pb(2+) solution and complete recovery of the adsorbed ion was possible (98+/-1%). The results of this investigation suggested that the use of Apt in the micro-composite form with PAA significantly enhanced the adsorptive features of Apt.     

Experimental determination of thermal conductivity of solid and liquid phases in Bi−Sn and Zn−Mg binary eutectic alloys

The thermal conductivities of solid phases, K_s, for Bi-43 wt.% Sn and Zn-0.15 wt.%Mg binary alloys at their eutectic temperature are found to be 28.0 τ 1.4 and 137.4–6.9 W/Km, respectively, with a radial heat flow apparatus. The thermal conductivity ratios, R, of liquid phase to solid phase for the same alloys at their eutectic temperature are found to be 0.93 and 0.78, respectively, with a Bridgman type directional solidification apparatus. Thus, the thermal conductivities of the liquid phases, K_L, for Bi-43 wt.%Sn and Zn-0.15 wt.%Mg binary alloys at their eutectic temperature are evaluated to be 26.0−1.3 and 107.2−5.4 W/Km, respectively, from the measured values of K_s and R.     

The determination of the total mass attenuation coefficients and the effective atomic numbers for concentrated colemanite and Emet colemanite clay

In this study, the attitude of some photon absorption energy related parameters such as coherent, Compton, photoelectric, pair-nuclear, pair-electronic, the total mass attenuation coefficients, effective atomic number, and electron density are investigated for two the mixtures, concentrated colemanite and Emet colemanite clay. In order to reach some desired conclusions, we calculated many of these parameters ranging from low energy (1 keV) to high energy (100 MeV) by using WinXCom program. Radiation shielding of the materials are compared in terms of B₂O₃ content. One of the most significant promise claimed by this study is that the excess or scarcity of B₂O₃ content in any material may not be a defining parameter alone for environment, construction, radiation shielding, and neutron capture applications. As well as B₂O₃ content, concentration values from quantitative and qualitative analysis of other compounds such as SiO₂, CaO, MgO, Fe₂O₃, Al₂O₃, PbO, K₂O contained in a material, if existed, must be taken into account.     

Synergistic and selective extraction of Cd2+ from acidic solution containing Cd2+, Co2+, Ni2+ by triisooctylamine (TIOA) and tributyl phosphate (TBP)

Selective and synergistic extraction of cadmium from acidic iodine solutions containing Cd²⁺, Co²⁺ and Ni²⁺using solvent extraction (SX) technique is presented in this study. The study has highlighted the importance of main and synergistic extractants composition. The mixtures have evident synergistic effects on Cd²⁺ with a synergistic enhancement factor of 2.22. The various experimental parameters were studied to determine the optimum extraction and stripping conditions of Cd²⁺. Under optimum conditions, the maximum extraction efficiency (99.7%) was achieved when using 1.5% (v/v) TIOA and 0.5% (v/v) TBP in dichloromethane within 5 min. Extracted Cd²⁺ was stripped effectively from the organic phase using 2.0 mol/L NaOH solution.