An expert system for predicting shear stress distribution in circular open channels using gene expression programming

The shear stress distribution in circular channels was modeled in this study using gene expression programming (GEP). 173 sets of reliable data were collected under four flow conditions for use in the training and testing stages. The effect of input variables on GEP modeling was studied and 15 different GEP models with individual, binary, ternary, and quaternary input combinations were investigated. The sensitivity analysis results demonstrate that dimensionless parameter y/P, where y is the transverse coordinate, and P is the wetted perimeter, is the most influential parameter with regard to the shear stress distribution in circular channels. GEP model 10, with the parameter y/P and Reynolds number (Re) as inputs, outperformed the other GEP models, with a coefficient of determination of 0.7814 for the testing data set. An equation was derived from the best GEP model and its results were compared with an artificial neural network (ANN) model and an equation based on the Shannon entropy proposed by other researchers. The GEP model, with an average RMSE of 0.0301, exhibits superior performance over the Shannon entropy-based equation, with an average RMSE of 0.1049, and the ANN model, with an average RMSE of 0.2815 for all flow depths.     

Agricultural Water Allocation by Integration of Hydro-Economic Modeling with Bayesian Networks and Random Forest Approaches

Water Resources Management - Sustainable utilization of water resources requires preventive measures that must be taken to promote optimal use of water resources together with consideration of...     

Advanced Bioresponsive Multitasking Hydrogels in the New Era of Biomedicine

Advanced forms of hydrogels have many inherently desirable properties and can be designed with different structures and functions. In particular, bioresponsive multifunctional hydrogels can carry out sophisticated biological functions. These include in situ single-cell approaches, capturing, analysis, and release of living cells, biomimetics of cell, tissue, and tumor-specific niches. They can allow in vivo cell manipulation and act as novel drug delivery systems, allowing diagnostic, therapeutic, vaccination, and immunotherapy methods. In the present review of multitasking hydrogels, new approaches and devices classified into point-of-care testing (POCT), microarrays, single-cell/rare cell approaches, artificial membranes, biomimetic modeling systems, nanodoctors, and microneedle patches are summarized. The potentials and application of each format are critically discussed, and some limitations are highlighted. Finally, how hydrogels can enable an “all-in-one platform” to play a key role in cancer therapy, regenerative medicine, and the treatment of inflammatory, degenerative, genetic, and metabolic diseases is being looked forward to.     

A novel 4H-SiC MESFET by lateral insulator region to improve the DC and RF characteristics

In this paper, a novel recessed gate metal–semiconductor field-effect transistor (RG-MESFET) is presented by modifying the depletion region and the electric field. The proposed structure improves the breakdown voltage, drain current and high frequency characteristics by embedding a lateral insulator region between drain and gate while is placed laterally into the metal gate and a silicon well exactly under the insulator region. We called this new structure as modified recess gate MESFET (MRG-MESFET). The radio frequency and direct current (DC) characteristics of the proposed structure is studied using numerical simulations and compared with a conventional MESFET (C-MESFET). The breakdown voltage, drain current DC transconductance and maximum power density of the proposed structure increase by 27%, 16.5%, 15% and 48%, respectively, relative to the C-MESFET. Also, the gate-source capacitance and the minimum noise figure of the proposed structure improve relative to the C-MESFET. The proposed structure can be used for high breakdown voltage, high saturation drain current, high DC transconductance, high power, high frequency, and low noise applications.     

Inverse radiation-conduction estimation of temperature-dependent emissivity using a combined method of genetic algorithmand conjugate gradient

The solution of an inverse, conduction-radiation problem in a two-dimensional rectangle is analyzed to determine the temperature-dependent emissivity at the boundary. The medium is gray, absorbing, emitting and isotropically scattering. The bounding surfaces are assumed to be opaque and diffuse. The inverse problem is solved by minimizing the performance function, which is expressed by the sum of square residuals between estimated and exact heat fluxes, using a combined method of genetic algorithm and conjugate gradient. The emissivity is assumed to be represented as a function of boundary temperature with unknown variables. Therefore, the inverse problem is treated by the estimation of these variables. Finally, four examples are presented to show the accuracy of the algorithm. The effect of the measurement errors on the accuracy of the inverse analysis is also investigated. Results show the algorithm can estimate the unknown emissivity when the measurement errors are neglected. Also it is found that increasing the measurement error decreases the accuracy of estimation of temperature-dependent emissivity.     

Self-standing crystalline TiO2 nanotubes/CNTs heterojunction membrane: synthesis and characterization

In the present study, we report for the first time synthesis of TiO(2) nanotubes/CNTs heterojunction membrane. Chemical vapor deposition (CVD) of CNTs at 650 °C in a mixture of H(2)/He atmosphere led to in situ detachment of the anodically fabricated TiO(2) nanotube layers from the Ti substrate underneath. Morphological and structural evolution of TiO(2) nanotubes after CNTs deposition were investigated by field- emission scanning electron microscopy (FESEM), glancing angle X-ray diffraction (GAXRD), and X-ray photoelectron spectroscopy (XPS) analyses.     

Surfactant modified zeolite carbon paste electrode (SMZ-CPE) as a nitrate selective electrode

A nitrate-selective electrode based on surfactant-modified zeolite (SMZ) particles into carbon paste was proposed (SMZ-CPE). The electrode was fully characterized in terms of composition, response time, ionic strength, thermal stability and usable pH range. The electrode containing 10% SMZ exhibited linear response range to nitrate species in the range of 1.00 × 10⁻⁶ to 1.00 × 10⁻³ M with a detection limit of 1.00 × 10⁻⁶ M and a Nernstian slope of 59.4 ± 0.7 mV per decade of nitrate concentration. The response of the electrode to nitrate remains constant in the pH ranges of 3.5–9.8 and 1.7–10.5 for 1.00 × 10⁻⁴ and 1.00 × 10⁻² M nitrate, respectively, and in presence of 1 × 10⁻⁴ to 1 × 10⁻³ M NaCl. The response of the electrode reaches to its equilibrium value within several seconds (10 s) after immersing the electrode in nitrate solution. Selectivity coefficients showed multivalent anions (such as arsenate, dichromate and sulfate) have higher interferences than monovalent anions (such as iodide, fluoride, bromide, chloride and thiocyanate). The electrode was used for determination of nitrate in an ammonium nitrate fertilizer sample, using direct potentiometry, and the satisfactory results were obtained. The electrode was also used for the potentiometric titration of nitrate. The validation of the obtained results in each case was proved by statistical “t” and “g” tests.     

Low-velocity impact damage response of fiberglass/magnesium fiber-metal laminates under different size and shape impactors

Low-velocity impact tests are performed on fiberglass/AZ31B-H24 magnesium fiber-metal laminates (FMLs) with various configurations in order to gain a better understanding of the effect of an impactor's features on the response of this type of FML. For that, impactors with two different shapes (hemispherical and sharp-edged) and sizes are used to impact the specimens. The impact response data, such as the deformation of the contact location and energy absorption, is obtained directly during the impact tests through the impact equipment, while mechanical sectioning was carried out to establish the extent of delaminated area and post-impact residual deformation. While the sharp-edged impactor caused the development of cracks on the metal constituent, and delamination within the specimens, the hemispherical ones imposed more influence over the residual deformation. Noticeable differences are observed in response of FML specimens made with two and three layers of magnesium, especially with respect to the energy absorption capacity. Moreover, finite-element analysis, as a major part of this study, has been employed to simulate the low-velocity impact response of FML specimens. The behavior of specimens has been simulated using the commercial finite-element code ABAQUS. The results imply that there is a good agreement between the experimental and numerical results.     

Memristor-based synaptic plasticity and unsupervised learning of spiking neural networks

Journal of Computational Electronics - Synaptic plasticity is studied herein using a voltage-driven memristor model. The bidirectional weight update technique is demonstrated, and significant...     

Enhanced water splitting through different substituted cobalt-salophen electrocatalysts

Synthesis of stable catalysts for water splitting is important for the renewable and clean energy production. Here, water oxidation activities of cobalt (II) complexes CoL¹-CoL³ (1–3) with salophen type ligands (N,N′-bis(salicylidene)-4-chloro-1,2-phenylendiamine (H₂L¹), N,N′-bis(salicylidene)-4-bromo-1,2-phenylendiamine (H₂L²) and N,N′-bis(salicylidene)-4-nitro-1,2-phenylendiamine (H₂L³)) are studied by electrochemical techniques, FE-SEM images and XRD patterns. Linear sweep voltammetry studies indicate that 2 and 3 have superior activities and only require the overpotential of 316 and 247 mV vs. RHE at current density of 10 mA/cm² with Tafel slopes of 75 and 50 mVdec^?1 at pH = 11. Experiments show relationships between the stability of the complexes and their catalytic activity. It is revealed that substituents on ligands affect the catalytic behaviors. Experiments show that in the presence of 2 and 3, the complexed cobalt ions are likely candidates as molecular catalysts for water oxidation. It is speculated that the O–O bond formation occurs by oxidizing the active center of cobalt complexes.