Viscosity and rheological behavior of castor–canola mixture

In this work, the effects of shear rate on viscosity of selected pure food grade oils (castor and canola) are investigated. The rheological behavior of castor–canola oil mixture is also studied through modeling the experimental data. The effect of shear rate on the variation of viscosity was clearly observed. Interpretations of the results from rheological models indicate that these food grade oils belong to pseudo‐plastic category. The results also show that among the six used mixing rules, Grunberg–Nissan model seems very well fitted to the experimental data.     

Prediction of hydrate formation conditions based on the vdWP‐type models at high pressures

Prediction of phase boundaries of gas hydrates has been done for several decades based on the vdWP (van der Waals and Platteeuw) hydrate equation and the classical thermodynamic equations for describing the water fugacities in water or ice phase. This procedure gives a reasonable prediction at low pressures, but when the pressure increases, above 10⁵ kPa, it shows a significant error. In the conventional vdWP‐type models it has been assumed that the volume difference between the empty hydrate lattice and pure liquid water is independent of the system pressure and temperature. In this work, different approaches for describing the volume dependency of pure liquid water and the empty hydrate lattice on the system pressure have been used to predict the hydrate equilibria based on the vdWP‐type model. Also, an expression is introduced to estimate the volume of methane hydrate lattice as a function of pressure and temperature. Finally, this method is extended to other hydrate formers, that is, ethane, carbon dioxide, xenon, and nitrogen. The predicted values are in good agreement with the experimental data both for L_w–H–V and L_w–H–L_hf phase boundaries.     

Extracting Optimal Rule Curve of Dam Reservoir Base on Stochastic Inflow

Water Resources Management - Declining rainfall, development of agricultural and industrial activities, population growth as well as Iran's location in arid and semi-arid regions of the planet...     

Kernel ridge regression model for sediment transport in open channel flow

Neural Computing and Applications - Sediment transport modeling is of primary importance for the determination of channel design velocity in lined channels. This study proposes to model sediment...     

Spinel nano-ferrites as low-cost (photo)electrocatalysts with unique electronic properties in solar energy conversion systems

Spinel nano-ferrites (MFe₂O₄, M: Co²⁺, Ni²⁺, …) are excellent low-cost candidates as (photo) electrocatalysts in solar-to-hydrogen energy conversion systems owing to their high dual electrochemical and photochemical activities. Their crystal structure consists of alternating tetrahedral and octahedral units that accommodate Fe³⁺/Fe²⁺ ions and another divalent ion in their interstices that give them unique electronic properties for (photo) electrocatalysis. Herein, the role of nano-ferrites as oxygen evolution reaction (OER) catalyst and counter-electrode catalyst in photovoltaic-electrolysis (PV-E) and photoelectrochemical (PEC) water splitting systems are highlighted. In particular, the recent advances on OER (photo) electrocatalysts based on spinel nano-ferrites and their design strategies such as doping, oxygen/cation defect engineering, as well as supporting and compositing with other materials are discussed and summarized. Finally, their advantages and performance limitations were presented, and future perspectives towards their improvement are suggested. Overall, this report is a critical review of the performance of spinel nano-ferrites as truly low-cost candidate catalysts with a wide natural abundance and easy preparation toward clean hydrogen generation.     

The effect of different process parameters on the TiCl4/internal donor/MgCl2/AlEt3 catalytic system using external donor and cyclohexylchloride

In this work, the effects of different process parameters were investigated on the performance of TiCl₄/internal donor/MgCl₂/AlEt₃ catalytic system and produced polyethylene in a semi-batch stirred reactor. Various methods such as Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscope (SEM), sieve shaker and melt flow index (MFI) measurement were used to investigate the catalyst activity and final polyethylene product. The results showed that cyclohexylchloride as promotor, in the presence of external donor, increased the catalyst activity up to 110% at optimum ratio to titanium. On the other hand, the polymer particle size and fine particles, which were directly related to the catalyst activity in the most cases, increased up to 15% in the presence of optimal halocarbon/Ti ratio and decreased up to 45% using hydrogen in the studied range. Also, in the optimal ratio, cyclohexylchloride increased the active site concentration and as a result, the MFI increased significantly. Also at low agitator speeds, due to low heat and mass transfer, the catalyst particles were severely fragmented and the particle size was decreased clearly. The results also showed that due to the special catalyst structure, pre-polymerization with propylene increased the catalyst activity by approximately two times compared to ethylene pre-polymerization.

     

Joint RSSD/AOA Source Localization: Bias Analysis and Asymptotically Efficient Estimator

In this paper we study blind source localization problem based on the joint received signal strength difference (RSSD) and angle of arrival (AOA) measurements with unknown transmit power of source. Since RSSD and AOA measurements are uncorrelated, combining two methods leads to a better performance for source localization. This paper focus on the pseudo linear estimator (PLE) with a closed-form and low complexity solution. One of the main limitations in this estimator is the bias created from the correlation between system matrix and error vector, which is not vanished by increasing the number of measurements. To overcome this problem first, we present a bias compensated PLE using the closed instrumental variable (IV). Then, for improving the localization performance a weighting IV estimator (WIV) is presented. Finally, for achieving the Cramer–Rao lower bound (CRLB) an improved WIV (IWIV) estimator is used based on the known relation between the estimated parameters of WIV estimator. The proposed IWIV estimator is proved to be asymptotically efficient (i.e., obtaining zero bias and the Cramer–Rao lower bound). Numerical simulations also verify the theoretical development and show source localization using hybrid information RSSD/AOA has a superior performance than RSSD and AOA solely.