Parameters Estimation for the New Four-Parameter Nonlinear Muskingum Model Using the Particle Swarm Optimization

The Muskingum model is a popular method for flood routing in river engineering. This model has several parameters, which should be estimated. Most of the techniques have applied to estimate these parameters to reduce the distance between observed flow and estimated flows. In this paper, for the first time, the parameters of a novel form of the nonlinear Muskingum model are estimated by the Particle Swarm Optimization (PSO) algorithm. The new Muskingum model, which have four parameters, is applied for three benchmark examples and one real case in Iran. The sum of the squared (SSQ) or absolute (SAD) deviations between the observed and estimated outflows was considered as objective functions. The results showed that although the new Muskingum model became more complex but this model by using PSO technique can improve the fit to observed flow especially in multiple-peak hydrographs.     

CMOS linear high performance push amplifier for WiMAX power amplifier

In this work a novel and efficient approach is proposed to optimize the linearity and efficiency of power amplifiers used in mobile WiMAX applications. A linear and high performance push amplifier is designed and implemented in 0.18 μm CMOS technology to enhance the linearity of a class-E switched-mode power amplifier. The proposed push amplifier consists of two sections; analog and switching sections. The analog section provides required linearity and the switching section guarantees satisfying total efficiency level. Each block is designed and optimized to meet required specifications. The core power amplifier which is a class-E switched-mode power amplifier is also designed to have maximum possible efficiency. The implemented circuit is simulated using HSPICERF and TSMC models for active and passive elements. The proposed power amplifier provides a maximum output power of 25 dBm and a power added efficiency (PAE) as high as 48% at 2.5 GHz operation frequency and supply voltage of 1.8 V. At 1 dB compression point this PA exhibits 23 dBm of output power with 42% PAE and 4.5% EVM which was appropriate for 64QAM OFDM signals.     

An improved process simulation system for ball-end milling of sculptured surfaces

A simulation system is developed in this paper, which deals with the geometry and mechanics of machining with ball-end milling cutters. The geometry of the workpiece, the cutter, and the cutter/workpiece engagement is modeled using a geometric simulation system. This module uses a commercial solid modeler (ACIS) as a geometric engine and automatically extracts the critical geometric information required for the physical simulation system. To calculate the instantaneous cutting forces, a new mechanistic force model is developed. This force model takes into account the variations of the cutting coefficients along the cutting edge, and considers the variations of the rake angle and the chip flow direction on the rake face. The calibration of the developed model is performed for half-immersion ball-end milling operation. The applicability of the developed system is verified experimentally for various up-hill angles. It is shown that as the up-hill angle increases, the ball-nose tip engagement decreases which in turn significantly affects the magnitude of the resultant forces. Also, lower cutting forces and powers are experienced if cutting with the vicinity of the tool tip is avoided.     

A Kinetic Study on the Catalytic Reductive Methylation of Acetylhydrazine

Catalytic reductive methylation of acetylhydrazine (AH) to dimethyl acetylhydrazine (DMAH) is a key step in the production of unsymmetrical dimethyl hydrazine (UDMH). The results of the present study show that the limiting step in this process is the hydrogenation of AH to mono methyl acetylhydrazine (MMAH). The kinetics of the hydrogenation of acetylhydrazone (AOH) using an activated carbon catalyst impregnated with 5 % palladium were studied in a stirred slurry reactor at 40–65 °C and 5–25 bar hydrogen pressure. Analysis of the data from this investigation indicates that the rate of hydrogenation is consistent with an Eley‐Rideal reaction mechanism. The activation energy for the hydrogenation was determined as 44 kJ/mol.     

Printed Wide-Slot Antenna for Wideband Applications

The design and analysis of a novel printed wide-slot antenna, fed by a microstrip line, for wideband communication systems is presented. Detailed simulation and experimental investigations are conducted to understand its behavior and optimize for broadband operation. The designed antenna has a wide operating bandwidth of over 120% (2.8-11.4 GHz) for S11 <-10 dB. In addition to being small in size, the antenna exhibits stable far-field radiation characteristics in the entire operating bandwidth, relatively high gain, and low cross polarization. By properly choosing the suitable slot shape, selecting similar feed shape and tuning their dimensions, the design with very wide operating bandwidth, relatively small size and improved radiation pattern is obtained. A comprehensive parametric study has been carried out to understand the effects of various dimensional parameters and to optimize the performance of the designed antenna. Results show that the impedance matching of this kind of antenna is greatly affected by the feed-slot combination and feed gap width, with the slot shape being a main contributor of the radiation characteristics. The simulated and measured Results for return loss, far-field E and H-plane radiation patterns, and gain of designed antenna are presented and discussed.     

Experimental investigation and development of new correlation for influences of temperature and concentration on dynamic viscosity of MWCNT-SiO2 (20-80)/20W50 hybrid nano-lubricant

In current research, MWCNT-SiO_2/oil hybrid nano-lubricant viscosity is experimentally examined. By dispersing 0.05%, 0.1%, 0.2%, 0.4%, 0.8% and 1% volume of MWCNTs and SiO_2 nanoparticle into the engine oil SAE 20W50, the temperature and solid volume fraction consequences were studied. At 40 to 100 ℃ temperature, the viscosities were assessed. The results indicated Newtonian behavior for the hybrid nano-lubricant. Moreover, solid volume fraction augmentation and temperature enhanced the viscosity enhancement of hybrid nano-lubricant. At highest solid volume fraction and temperature, nano-lubricant viscosity was 171% greater compared to pure 20W50. Existed models lack the ability to predict the hybrid nano-lubricant viscosity. Thus, a new correlation regarding solid volume fraction and temperature was suggested with R-squared of 0.9943.     

Studying the Potential Application of Electrospun Polyethylene Terephthalate/Graphene Oxide Nanofibers as Electroconductive Cardiac Patch

Nowadays, engineering‐based cardiac patches aim to accelerate cardiac regeneration in myocardial infarcted tissues. Considering the fundamental role of cardiac electrophysiology in myocardial function, this study aims to investigate graphene oxide (GO) incorporation in the polyethylene terephthalate (PET) nanofibrous scaffold, as a conductive cardiac patch. The PET/GO nanocomposites are prepared using the uniaxial nozzle and coaxial nozzle electrospinning processes and comprehensively evaluated. The morphological observation indicates a uniform beaded free morphology with an average diameter of 147 ± 38 and 253 ± 67 nm for solid and core–shell nanocomposite fibers, respectively. Addition of GO to the PET nanofibers in a concentration of 0.05 wt% remarkably increases the Young modulus of mats from 30 ± 0.03 to 60 ± 0.02 and 69 ± 0.08 MPa for solid and core–shell nanofibers, respectively. Also, the electroconductivity is improved from 0.7 × 10^?6 to 1.175 × 10^?6 and 1.3 × 10^?6 S cm^?1 for solid and core–shell nanofibers, which are in the range of cardiac electroactivity values. PET/GO substrate interestingly supports human umbilical vein endothelial cells’ spreading morphology and cardiomyocyte elongated morphology, mainly where the GO nanosheets are distributed near the surface of nanofibers. In conclusion, the core–shell electrospun PET/GO nanocomposite fibers are suggested as a potential electroactive cardiac patch to improve cardiac cell attachment and proliferation.     

Neural computing approach for predicting vaporization enthalpy of pure hydrocarbons and petroleum fractions

The current collaboration was aimed to approximate the heat of vaporization for petroleum fractions and pure hydrocarbons through using the multi-layer perceptron artificial neural network (MLP-ANN) based on the specific gravity, molecular weight, and boiling point temperature. Furthermore, Levenberg Marquardt algorithm was utilized to train the ANN structure and optimize its tuning parameters. Another comparison was carried out between the outcomes of suggested MLP-ANN model and six well-known correlations. Better results were observed for predicting heat of vaporization by the MLP-ANN model with the obtained value of mean relative error (MRE) and R-squared (R²) equal to 1.31% and 0.9962%, respectively. This computational approach can be applied in the petroleum engineering for a precise determination of heat of vaporization.     

Regulation of striatal dopamine release by metabotropic glutamate receptors

This study examined the temporal relationship between aminoglycoside ototoxicity and the onset of auditory function in the rat. A single dose of gentamicin sulfate (200 mg/kg) and furosemide (100 mg/kg) was administered on postnatal day 6 (P6), P7, P8, P9, or P10, just before the onset of auditory function. Ototoxicity was assessed by the elevation of auditory brain stem response (ABR) thresholds, recorded once the rats had matured. The ABRs were evoked by acoustic clicks and tone pips. The thresholds of control and P6- and P7-treated animals did not differ significantly from each other. Thresholds of some P8- and all P9-treated animals were elevated. The P10-treated animals were deafened, according to these ABR criteria. These data suggest that the potential for aminoglycoside ototoxicity develops rapidly between P8 and P10, just before the onset of auditory function.     

Comparison of the born iterative method and tarantola's method for an electromagnetic time-domain inverse problem

Two methods of solving the nonlinear two-dimensional electromagnetic inverse scattering problem in the time domain are considered. These are the Born iterative method and the method originally proposed by Tarantola for the seismic reflection inverse problems. The former is based on Born-type iterations on an integral equation, whereby at each iteration the problem is linearized, and its solution is found via a regularized optimization. The latter also uses an iterative method to solve the nonlinear system of equations. Although it linearizes the problem at each stage as well, no optimization is carried out at each iteration; rather the problem as a whole is posed as a (regularized) optimization. Each method is described briefly and its computational complexity is analyzed. Tarantola's method is shown to have a lower numerical complexity compared to the Born iterative method for each iteration, but in the examples considered, required more iterations to converge. Both methods perform well when inverting a smooth profile; however, the Born iterative method gave better results in resolving localized point scatterers.