The present study proposes modified solar-driven combined power and ejector refrigeration cycles (CPERCs) for low-temperature heat sources. The proposed cycles are constructed from combination of simple organic Rankine cycle (ORC), ORC with an internal heat exchanger (IHE), a regenerative ORC, and regenerative ORC with an IHE, with ejector refrigeration cycle (ERC). The ejector is driven by the exhausts from the turbine to produce more power and refrigeration, simultaneously. The first and second laws of thermodynamics have been applied to each cycle using R245fa and isobutene as working fluids. With respect to each proposed cycle, thermodynamic model has been validated by previous works. Using isobutene as a working fluid, the maximum thermal and exergetic efficiencies have been obtained 50.46 and 58.08 %, respectively, which corresponded to regenerative combined power and ejector refrigeration cycle with an IHE. In general, the thermal efficiency of system is improved by 7.54 and 5.76 % through this state-of-art modification using R245fa and isobutene as working fluids, respectively. This demonstrated that isobutene can be a good candidate for CPERCs based on the first and second laws of thermodynamics. Throughout these modifications, cooling capacity and net produced power of cycles are also increased, successively. These results show that proposed cycles can produce more power and refrigeration compared with the previous cycles. These proposed cycles are more especially applicable for refrigeration purposes, since the power/refrigeration ratio (R) is smaller than unit. From the second law of thermodynamics point of view, among all components in the proposed cycles, generator has the highest contribution in exergy losses of the overall cycle. At the end of this study, sensitivity analysis of different key parameters of the proposed cycles has been conducted which is highly beneficial to be more familiar with the characteristics of these proposed cycles.

La mondialisation qui a pour corollaire l’uniformisation s’étend par-delà les cultures traditionnelles, les lamine, quand bien même celles-ci servent d’argument commercial. Peut-il en aller autrement ? Les cultures se brassent, s’enrichissent, se métissent, laissant, çà et là, émerger quelques reliefs, forger une nouvelle culture fruit de ce métissage. Un monde à cheval entre tradition et modernité. Conflits en apparence apaisés, compromis ; qu’en est-il dans la rude réalité du temps, d’une économie malgré tout libérale et dominante qui impose une forme d’alignement sur le reste du monde ?

Copper metal and its alloys are most used over industries, because it holds excellent conductivity and natural corrosion protectiveness against air / moisture. However, copper undergoes degradation in presence of aggressive 3.5% NaCl. Protective coating is one of the practical methods to safeguard copper metal. In this study, 2-amino-4-methyl-pyridine (AMP) was coated as self-assembled monolayer method (SAMs) with different immersion periods (12 h / 24 h) and investigated the corrosion potential against 3.5 % NaCl medium. Chemical composition of AMP/SAM/Cu was characterized using Fourier-transform infrared spectroscopy (FT-IR) and morphological analysis using Atomic force microscopy (AFM) techniques. AMP’s corrosion inhibition potential were evaluated via electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDS) analysis. Quantum chemical calculations and molecular dynamics (MD) simulations explained the stronger adsorption of AMP over copper metal surface via self-assembly method. The corrosion analysis revealed that AMP’s SAM formation (24 h immersion) enhances the corrosion protection of Cu metal, which is mainly due to the uniform thin adhesive compact layer formation and blocks incoming corrosive chloride ions. Electrochemical studies evident that AMP’s significant inhibition efficiency (90%) and mixed mode mechanism in PDS. Molecular modelling investigation supported well for the Cu-N (from AMP) bond formation.

The paper contains an implemented approach to stress recognition based on registered sound parameters LZE, LZeq, LZF and LZS at different speech levels in working environment. Said approach combines apparatus k – nearest neighbors (k-NN) with metric distances Euclidean, Cityblock, Minkowski and Chebychev, Decision tree (DT) method with CART training algorithm and artificial neural networks (ANN) with reverted error propagation in Levenberg-Marquadt (LM) and Scaled Conjugate Gradient (SCG) training. A matching has been done between parameters of models according k-NN method as maximum accuracy of 93.99 % with minimum parameter k = 3 has been registered for Cityblock distance. There has been established a fourth optimum level of nodes pruning from the structure for multiple choice of the classification group using DT method with achieved accuracy of 99.05 %. In investigation of LM algorithm during training of networks using purelin, tansig and logsig transfer functions, there has been achieved identical accuracy of 99.99 %. With regard to a minimal indication of criterion Mean Squared Error (MSE) 0.0064 with 11 hidden neurons, there has been selected ANN architecture with tansig output activation.

Background: The dose distributions were expressed on percentage depth dose (PDD). The measurements of PDDs were done as a function of irradiation field size with an uncertainty of 2% as recommended by IAEA protocols. The objective of this study is to evaluate mathematically an empirical law governs the skin dose with photon beam energy and irradiation field size based on experiments data of dose distributions for checking out the radiotherapy quality at the patient’s skin.\nMethods: based on PDDs measured in water phantom using PTW ionization chamber, we evaluate the quality of skin dose by introducing the parameter of build-up index. The latter is calculated with field size for two photon beam energies 6 MV and 18 MV.\nResults: The dose build-up quality increased linearly with irradiation field size and the slope of the line for 18 MV is very high than the slope line for 6 MV that means while cancer treatment, the delivered dose at sallower depths is very high for photon beam of 6 MV than photon beam of 18 MV.\nConclusion: the medical physicist and physician should take this property of the photon beam energy for IMRT. The photon beam of 6 MV is more efficient than the photon beam of 18 MV.

In this study, a comprehensive energy and exergy analysis for Organic Rankine Cycle Waste Heat Recovery (ORC-WHR) system integrated with a coal-fired power plant was constructed. In order to conduct thermodynamic analysis of the ORC-WHR system, industrial data obtained from a coal-fired power plant operating at a maximum capacity of 660 MW was used. As working fluid, R123, R236FA, R245CA, R245FA and R365MFC organic fluids were considered in the existing system. Energy and exergy analyzes were applied to each component of the ORC-WHR system. The performance parameters of the ORC-WHR system were determined according to flue gas temperature and evaporator inlet pressure. According to the obtained results, the best performance value in respect to thermal and general exergy efficiencies and net ORC turbine power output was achieved when the organic fluid of R245FA was used in the system. When the coal-fired power plant with the integrated ORC-WHR system was operated at full load, 4.78 MW of additional electricity generation was recovered and so the total system efficiency of the power plant was increased by 0.322%. Furthermore, the investment, operation and maintenance costs required for the installation of the ORC-WHR unit were handled separately and the return on investment (ROI) was calculated as 5.02 years.