Regression-Based Models for Predicting Discharge Coefficient of Triangular Side Orifice

- This study introduced another technique to predict the discharge coefficient (Cd) of the triangular side orifice (TSO). This technique is based on the SPSS software as multiple linear regression (MLR) and multiple nonlinear regression (MNLR) models. These models were established using 570 experimental datasets, 70 and 30% for calibration and testing stages, respectively. These sets considered five non-dimensional parameters, including (orifice crest height, orifice length, orifice height, upstream flow depth, and Froude number of the main channel). Results showed that the MLR and MNLR models in the calibrating stage had higher determination coefficients and lower errors. In addition, the importance of the input parameters was investigated, showing that the orifice crest height and Froude number highly affect the discharge coefficient value by 36%. In the testing stage, the estimated discharge coefficient by the MLR and MNLR models stayed within the range ±12 and ‡5%, respectively, of the experimental values. The MNLR model demonstrated a high level of equivalence compared to previous studies, which provided a mathematical expression to easily predict the TSO\u27s discharge coefficient

An Application of Genetic Algorithms to Time-Cost-Quality Trade-off in Construction Industry

Time, cost and quality are used for measuring project success. So, they are considered the most important objectives in construction projects. Project managers should deliver their project on time with minimum cost and at a certain quality level. To get these conflicting objectives, project managers introduce many possible methods of execution (modes) for each activity in the project. This paper presents an optimization model that supports project managers and decision makers in performing this challenging task and leads to identification of the best solution. Developed model is based on Genetic Algorithms which have many advantages over traditional optimization techniques and considered suitable for more than one objective function. The developed Genetic Algorithms model considers target function, design variables affecting that target, and problem constraints. Through application to two projects, the model feasibility is examined. The results show that the proposed approach can help the practitioners in considering different modes for activities and easily find minimum cost for a certain project time meeting the quality requirements. The model can easily reach the best solution from huge number of solutions in reasonable running time. In addition, the results tell that the present method can be used in generating a group of optimal solutions. Key words: construction projects; time-cost-quality; trade-off; optimization; Genetic Algorithm

Spin Transfer Torque in Antiferromagnetic Spin-Valves: From Clean to Disordered Regimes

Current-driven spin torques in metallic spin-valves composed of antiferromagnets are theoretically studied using the non-equilibrium Green's function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin-valve, the coherent and exchange torques can be either in the plane, {\alpha} n\times(q \times n) or out of the plane {\alpha} n \times q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin-valvesComment: 10 pages, 11 figure

Determination of some metal ions in aquatic environs by atomic absorption spectrometry after concentration with modified silica

The uptake behaviour of porous silica modified with N-propylsalicylaldimine (IE11) and Cd (II), Cr (III), Cu (II), Mn (II) and Pb (II) metal ions were studied. The Log kd values were found to be within the range 2.19 - 5.16 depending on pH and time of stirring. IE11 was used in the separation and preconcentration of Cd (II), Cr (III, VI), Cu (II), Mn (II, VII) and Pb (II) from some natural water samples. The data were compared with those obtained by the solvent extraction method (APDC/MIBK). The proposed methodology permits verification of improvements in the water quality of the Nile River, probably attributed to moderately high floods of the last few years. The method was found to be accurate and precise and not subject to random error

Photometric and Spectroscopic Analysis of the SX Phe Star BL Cam

In the present paper, we report the photometric and spectroscopic observations obtained by the 1.88 m telescope at the Kottamia astronomical observatory of the pulsating star BL Cam. Fourier analysis of the light curves reveals that the fundamental mode has two harmonics. The O-C method is used to establish the period changes. So far, the analysis has been very successful in mapping the pulsation amplitude of the star across the instability strip. By using the formalism of Eddington and Plakidis (1929), we found significant results and strong indications of the evolutionary period change. A total of 55 new maximum light timings are reported. New values of (1/P) dP/dt are estimated using the O-C diagram based on all newly obtained times of maximum light combined with those taken from the literature, assuming the periods are decreasing and changing smoothly. To compute the effective temperature and surface gravity of the star, we performed model atmosphere analysis on its spectra. The physical parameters of the star are calculated and compared with the evolutionary models

Majorana bound states in d-wave superconductor planar Josephson junction

We study phase-controlled planar Josephson junction comprising a two-dimensional electron gas with strong spin-orbit coupling and d-wave superconductors, which have an advantage of high critical temperature. We show that a region between the two superconductors can be tuned into topological state by the in-plane Zeeman field, and can host Majorana bound states. The phase diagram as a function of the Zeeman field, chemical potential, and the phase difference between superconductors exhibits the appearance of robust Majorana bound states for a wide range of parameters. We further investigate the behavior of the topological gap and its dependence on the type of d-wave pairing, i.e., d, d+is, or d+id', and note the difficulties that can arise due to the presence of gapless excitations in pure d-wave superconductors. On the other hand, the planar Josephson junctions based on superconductors with d+is and d+id' pairings can potentially lead to realizations of Majorana bound states. Our proposal can be realized in twisted bilayer d-wave superconductors realizable in mechanically exfoliated van der Waals copper oxide heterostructures.Comment: 4 pages, 4 figure

Reducción de las enfermedades cardiovasculares e hipercolesterolemia por mezclas de extractos de plantas comestibles: un estudio del perfil lipídico, estrés oxidativo y testosterona en ratas

The present study was postulated to prepare and evaluate the influence of two plant food extract mixtures on plasma lipid profile, oxidative stress and testosterone levels in rats fed a hypercholesterolemic diet. The safety of the studied extract mixtures was evaluated through the determination of liver and kidney functions. The total phenolic contents, tocopherols, fatty acids and unsaponifiable matter (UNSAP) in the extract mixtures were determined. Rats fed a hypercholesterolemic diet were given a daily oral dose (300 mg/kg rat body weight) of either mixture I or II for a month and compared with a control hypercholesterolemic group and a normal control group. Results showed that α-tocopherol was 0.750 and 4.017 mg, γ-tocopherol was 0.564 mg and 0 and δ-tocopherol was 15.23mg and 0.634mg/100g for mixtures I and II, respectively. The phenolic contents in mixtures I and II were 36.74 and 23.72 g gallic acid equivalent/100g mixture, respectively. The GLC investigation of UNSAP revealed that stigmasterol and b-sitosterol were the major phytosterols in mixtures I and II, respectively followed by campesterol in both. The GLC analysis of the fatty acids showed that oleic acid was the major fatty acid in both extract mixtures. Results from the animal experiment showed that feeding a hypercholesterolemic diet produced a significant increase in total lipids, total cholesterol (T-Ch), triglycerides (TGs), low density lipoprotein cholesterol (LDLCh), T-Ch/HDL-Ch, TGs/HDL-Ch and malondialdehyde (MDA) and a significant reduction in high density lipoprotein cholesterol (HDL-Ch), vitamin E, b-carotene and testosterone. Rats fed a hypercholesterolemic diet and given mixture I or II showed significant improvements in plasma lipid profile compared to the hypercholesterolemic control group. This improvement was associated with a significant reduction in oxidative stress reflected by an elevation in plasma levels of antioxidants (vitamin E and b-carotene) and a reduction in plasma MDA levels. The plasma level of testosterone increased significantly in the rats fed the hypercholesterolemic diet and given mixture I or II compared to the hypercholesterolemic control. Plasma testosterone showed a significant negative correlation with plasma TGs and TGs/HDL-Ch in the hypercholesterolemic control rats. The studied extract mixtures showed complete safety towards liver and kidney functions. In conclusion the tested extract mixtures showed an improvement in the plasma lipid profile, a significant increase in testosterone and a decrease in oxidative stress with promising prevention of atherosclerosis and cardiovascular diseases. The antiatherogenic effect of the extract mixtures may be due to the presence of phenolic compounds, phytosterols, tocopherols and unsaturated fatty acids.El presente estudio fue dirigido a preparar y evaluar la influencia de dos mezclas de extractos de plantas comestibles sobre el perfil lipídico del plasma, estrés oxidativo y nivel de testosterona en ratas alimentadas con una dieta hipercolesterolemica. La salubridad de las mezclas de extractos estudiadas fue evaluada mediante la determinación de las funciones del hígado y del riñón. El contenido total de fenoles, tocoferoles, ácidos grasos, y materia insaponificable (UNSAP) fueron determinado en la mezclas de extractos. Las ratas fueron alimentadas con dietas hipercolesterolémica junto con una dosis oral diaria de (300 mg/kg de peso) cada mezcla I y II durante un mes y comparada con un control hipercolesterolémico y un control normal. Los resultados muestran que el contenido de α-tocopherol fue 0.750 y 4.017 mg, γ-tocopherol fue 0.564 mg y 0 y δ-tocopherol fue 15.23mg y 0.634mg/100g de mezcla I y II, respectivamente. El contenido de fenoles en las mezcla I and II fue 36.74 y 23.72 g equivalentes de ácido gálico/100g de mezcla, respectivamente. La investigación por GLC de UNSAP reveló que el estigmasterol y el b-sitosterol fueron los principales fitoesteroles de las mezclas I y II, respectivamente seguido por el campesterol en ambos casos. El análisis por GLC de los ácidos grasos mostró que el ácido oleico fue el ácido graso mayoritario en ambas mezclas de extractos. Los resultados con animales de experimentación mostraron que la alimentación con dietas hipercolesterolémicas produce un incremento significativo en los lípidos totales, colesterol total (T-Ch), triglicéridos (TGs), colesterol en lipoproteínas de baja densidad (LDL-Ch), en las relaciones T-Ch/ HDL-Ch y TGs/HDL-Ch y malondialdehido (MDA) y una significativa reducción en el colesterol de las lipoproteínas de alta densidad (HDL-Ch), vitamina E, b-caroteno and testosterona. Las ratas alimentadas con dietas hipercolesterolémicas junto con mezclas I y II mostraron una mejora significativa del perfil lipídico del plasma comparado con el grupo control hypercholesterolémico. Esta mejora estuvo asociada con una significativa reducción del estrés oxidativo reflejado por la elevación de los niveles de antioxidantes en el plasma (vitamin E y bcarotene) y reducción de los niveles de MDA en plasma. Los niveles de testosterona en plasma aumentaron significativamente en ratas alimentadas con dietas hipercolesterolémicas junto con mezclas I y II en comparación con el control hipercolesterolémico. La testosterona del plasma mostró una correlación negativa significativa con los TGs y TGs/HDL-Ch en ratas control hipercolesterolémicas. Las mezclas de los extractos estudiados mostraron una completa salubridad hacia las funciones del hígado y el riñón. En conclusión las mezclas mostraron una mejora del perfil lipídico del plasma, un significativo incremento en la testosterona, y un descenso del estrés oxidativo con una prometedora prevención de las enfermedades cardiovasculares y ateroesclerosis. El efecto anti-aterogénico de las mezclas de los extractos puede ser debida a la presencia de compuestos fenólicos, fitoesteroles, tocoferoles y ácidos grasos insaturados

Antiscaling Evaluation and Quantum Chemical Studies of Nitrogen-Free Organophosphorus Compounds for Oilfield Scale Management

Nonpolymeric aminomethylenephosphonates are widely used as powerful scale inhibitors in the petroleum industry. However, most of these inhibitors have certain drawbacks, such as low biodegradability and incompatibilities with high calcium brines. Therefore, there is a great need to explore more biodegradable phosphonated oilfield scale inhibitors affording high calcium-ion tolerance. In this project, known and new nitrogen-free phosphonates have been tested as scale inhibitors against carbonate and sulfate scales according to the Heidrun oilfield, Norway. The considered nitrogen-free scale inhibitors are 1,2,4-phosphonobutanetricarboxylic acid (PBTCA), hydroxyphosphonoacetic acid (HPAA), phosphonoacetic acid (PAA), and 3-phosphonopropanoic acid (PPA). A high-pressure dynamic tube-blocking test, calcium tolerance, thermal aging, and seawater biodegradation were used to assess the antiscaling performance of these inhibitors. A very good to excellent performance of all nitrogen-free phosphonate scale inhibitors has been observed against the calcite scaling. A biodegradable naturally occurring PAA displayed a very good calcite inhibition efficiency and afforded excellent thermal stability at 130 °C for 7 days under anaerobic conditions. PAA also gave outstanding tolerance activity with all concentrations up to 10 000 ppm calcium ions. Density functional theory (DFT) simulations predicted higher affinities of the commercial SIs compared to the nitrogen-free molecules, which is in line with their calcium compatibilities. The high calcium tolerance of nitrogen-free molecules makes them more efficient than commercial inhibitors. Further, DFT solid-state simulations reveal that the affinities of the nitrogen-free molecules for the calcite surface are higher than the barite surface, which agrees well with the experimental fail inhibitor concentration (FIC) data. The sluggish and complicated kinetics of the barite scale formation compared to the calcite scale explain well the high concentrations of the nitrogen-free molecules required for barite inhibition. In summary, our results showed that the nitrogen-free molecules show good potential as scale inhibitors for both calcite and barite. However, for the latter scale, further optimization is needed for optimal performance.publishedVersio