A generalized set of correlations for plus fraction characterization

The importance of accurate determination of the critical properties of plus fractions in prediction of phase behaviour of hydrocarbon mixtures by equations of state is well known in the petroleum industry. It has been stated in various papers (Elsharkawy, 2001) that using the plus fraction as a single group in equation of state calculations reduces the accuracy of the results. However in this work it has been shown that using the proper values of critical temperature and pressure for the plus fraction group can estimate the properties of hydrocarbon mixtures, and they are accurate enough to be used in reservoir engineering and enhanced oil recovery calculations. In this paper, a new method is proposed for calculating the critical properties of plus fractions of petroleum fluids. One can use this method either in predicting critical pressure and temperature of single carbon numbers (SCNs) after the splitting process or in predicting critical pressure and temperature of the plus fraction as a single group. A comparison study is performed against Riazi-Daubert correlation (Riazi and Daubert, 1987) and Sancet correlations (Sancet, 2007) for 25 oil samples taken from 14 fields from southwest Iran. The results indicate the superiority of the proposed method to the Riazi-Daubert and Sancet correlations.     

VLS and VS effect on ferromagnetic behaviour of SnO2 nanobelts

Fabrication of SnO₂ nanobelts has been carried out by employing vapour liquid solid (VLS) and vapour solid (VS) mechanism. Nanobelts obtained by VLS mechanism were fabricated at relatively low temperature using Fe powders as a catalyst by means of chemical vapour deposition (CVD) technique. Direct thermal evaporation of SnO₂ nanobelts was carried out at 1350°C in the atmosphere of Argon gas via VS mechanism. In both cases, ramp rate was adjusted to 10°C/min. The structural, compositional and morphological characterisations of synthesised SnO₂ nanobelts were conducted by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X?ray spectroscopy (EDS). Magnetic behaviour of the nanobelts was studied by vibrating sample magnetometer (VSM). Cathodoluminescence (CL) spectra were studied using Renishaw Raman spectroscopy system. The growth of nanobelts is found to be homogeneous and dense. The nanobelts formed by VLS mechanism show ferromagnetic behaviour along with some other exciting results whereas the nanobelts formed by VS mechanism show a diamagnetic behaviour. The observed room temperature ferromagnetism in SnO₂ nanobelts is superior to other oxides.     

Novel Linear Piezo-resistive Auxetic Meta-Sensors with Low Young's Modulus by a Core–Shell Conceptual Design and Electromechanical Modelling

Production of piezo-resistive auxetic sensors is usually carried out through mixing and coating methods. Although these methods are beneficial, Young's modulus of mixed sensors becomes high because of using a high percentage of sensing elements while the durability of coated sensors gets low due to the separation of sensing elements from the sensor surface. This article presents a new core–shell metamaterial model to address the mentioned problems. The shell and the core are produced of polydimethylsiloxane (PDMS) rubber and a mixture of PDMS/graphite powders (73.45 wt% graphite powders), respectively. A finite element model is developed via COMSOL software to predict the electromechanical behaviors of the created sensor and verified by an experimental study. Scanning electron microscope imaging is conducted to detect the separations of the graphite particles. The main important feature of this meta-sensor is to possess a linear sensitivity due to having zero Poisson's ratio. The advantage of this method is that Young's modulus of the sensor does not decrease (unlike the mixing method), and the sensor-coated particles do not separate from the sensor after a while (unlike the coating method). The introduced model has advantages that promote potential applications such as using sensory gloves to detect, for instance, human hand movements.     

Comprehensive energy and economic transient analysis of an off-grid hydrogen car-integrated zero energy building

Clean Technologies and Environmental Policy - In this study, for the first time, an off-grid zero-energy building with hydrogen energy storage integrated with two hydrogen cars is simulated and...     

A FinBOX Based Ge FinEHBTFET: Design and Investigation

Silicon - In this work, we propose a Germanium Fin Buried Oxide (FinBOX) Fin Electron-Hole Bilayer Tunnel FET (FBF-EHBTFET) structure. The proposed structure eliminates the gated underlaps and...     

ILSBMR: improved LSBMR (ILSBMR) method

The Least Significant Bit Matching Revisited (LSBMR) is among the most commonly used methods on image steganography, aiming to make only smaller changes in an image. While security is considered as one of the basic evaluation criteria for steganography techniques and notably, LSBMR can be easily recognized due to its well-known structure, it is important to find a way to help improve this approach so that it might cause less variation in the image and also increase security. To this end, the current paper deploys divided blocks of the original cover image and a selection of the best layout to embed secret message bits from each block into color images by using LSBMR. The simulation results indicate that this improved method makes small changes in the image and increases its security, compared to the LSBMR technique.     

Kinetic study of slaughterhouse wastewater treatment by electrocoagulation using Fe electrodes

In this study, treatment of slaughterhouse wastewater by electrocoagulation was investigated in batch system using Fe electrodes. The effect of various variables such as electrode number, current density and operating time was tested. Pollutant removal efficiency increased with increasing electrode number and operating time. The biochemical oxygen demand (BOD(5))(,) chemical oxygen demand (COD), total suspended solid (TSS), and total nitrogen (TN) removal efficiencies using eight electrodes at a contact time of 50 min and a current density of 10 A/m(2) were 66, 62, 60, and 56%, respectively. Higher electrode numbers will allow shorter operating times to achieve certain removal efficiencies. Also, removal efficiencies increased by increasing the current density; the highest removal efficiencies of BOD(5,) COD, TSS, and TN at a contact time of 50 min and a current density of 25 A/m(2) were 97, 93, 81, and 84%, respectively. The results also show that the reactor pH varies directly with the current density; at 25 A/m(2), the reactor pH increased from an initial value of 7.1 to 7.7 after 50 min. The experimental results showed that the kinetics of BOD(5), COD, TSS and TN removal could be fitted adequately using a first order kinetic model (higher R(2)).     

Photocatalytic degradation of dimethyl sulphoxide by CdS/TiO2 core/shell catalyst: A novel measurement method

In the present research, the photocatalytic degradation of dimethyl sulphoxide (DMSO) by means of CdS/TiO₂ core/shell nanocomposite was investigated and modelled for the direct measurement of degradation rate. Instead of common measurement methods, liquid freezing point measurement was used in order to determine the rate of DMSO decomposition. To model the photocatalytic behaviour, two empirical-statistical equations based on photocatalytic retention time, amount of catalyst and pollutant were introduced. The effect of parameters such as retention time, amount of catalyst and pollutant were studied by statistical methods. The design of experiments, acquisition and optimization of statistical models was performed by response surface methodology (RSM) through central composite design (CCD). The rates of disappearance fitted the Langmuir-Hinshelwood kinetics model and the parameter k was determined to be up to 0.0105 per minute for a low concentration and 0.0073 per minute for a high concentration of DMSO. In addition, more than 85% degradation of 1% DMSO was attained by 8% catalyst in 150 minutes. Finally, the accuracy and consistency of the statistical models was verified by the HPLC method and ~ ± 2.7% difference was observed. The other results indicate that the CdS/TiO₂ nano photocatalyst can efficiently remove dimethyl sulphoxide from wastewater under visible light irradiation.     

Simultaneous Determination of Nitrite and Nitrate in Milk Samples by Ion Chromatography Method and Estimation of Dietary Intake

The presence of nitrate and nitrite in foods may be considered hazardous after ingestion in the gastrointestinal tract due to their reaction with naturally occurred secondary amines to form potentially carcinogenic nitrosamines. Due to this fact, a new method was developed in this study for the simultaneous determination of nitrite and nitrate in milk samples using by ion chromatography. Proposed mobile phase composed of sodium hydrogen carbonate and sodium carbonate (1.0 and 3.2 mmol/L) with a flow rate of 0.7 ml/min. The average recoveries for nitrate and nitrite were higher than 86 and 88%, respectively. The limit of detection for nitrate and nitrite were 0.24 and 0.09 mg/L, respectively. The results of 102 real milk samples showed nitrate was found in all of the samples (100%) with a mean of 34 ± 11 mg/L, while nitrite was found in none of the samples. The mean intake of nitrate in all age groups was lower than World Health Organization guideline. The present assessment concludes that the maximum contaminant level was equal to 82.8 mg/L nitrate. This method was fast, sensitive and accurate and is capable of being an alternative method in food control laboratories for investigation of nitrite and nitrate content. This is the first study of the determination and survey of nitrite and nitrate and exposure assessment of the Iranian population to nitrite and nitrate level in milk, which was widely used in infants and adolescents as one of the basic food components.