Numerical study of heat transfer enhancement from a heated circular cylinder by using nanofluid and transverse oscillation

Journal of Thermal Analysis and Calorimetry - Adding nanoparticles into the base fluid and oscillating the target surface are two passive and active techniques, respectively, for heat transfer...     

A Surrogate Modelling Approach Based on Nonlinear Dimension Reduction for Uncertainty Quantification in Groundwater Flow Models

Transport in Porous Media - In this paper, we develop a surrogate modelling approach for capturing the output field (e.g. the pressure head) from groundwater flow models involving a stochastic...     

Hollow-Core Fiber: Breaking the Nonlinearity Limits of Silica Fiber in Long-Distance Green Laser Pulse Delivery

Hollow-core fiber (HCF), in which >99.99% of the light is guided in a central air (or vacuum) filled core, is a radically new fiber technology offering the potential to overcome the nonlinear limits associated with the delivery of high-brightness laser pulses over long distances in conventional solid-core fiber. Overcoming these limits is particularly challenging at visible wavelengths where the core sizes of single-mode fibers (SMFs) are reduced. In this work, the delivery of near-diffraction-limited, kilowatt-peak-power, sub-nanosecond laser pulses in the green wavelength range over hundred-meter scale lengths of a hollow-core anti-resonant fiber (HC-ARF) which offers broadband low-loss guidance in the visible is experimentally demonstrated. Substantially reduced nonlinearity-induced spectral broadening is observed relative to silica-core SMF. The simulation further confirms that the broadening observed (in the HC-ARF) is entirely due to the interaction of the light with the air in the core and thus can effectively be eliminated by evacuating the fiber. Moreover, access to lower-loss is noted, and visible guiding HC-ARFs (that are now becoming available) will improve the throughput efficiency and extend power delivery to kilometer distance scales. The results demonstrated here pave the way for future long-distance HCF pulse delivery applications, such as remote industrial e-mobility manufacturing.     

An Improvement of Ostrowski’s and King’s Techniques with Optimal Convergence Order Eight

In this paper, we first establish a new class of three-point methods based on the two-point optimal method of Ostrowski. Analysis of convergence shows that any method of our class arrives at eighth order of convergence by using three evaluations of the function and one evaluation of the first derivative per iteration. Thus, this order agrees with the conjecture of Kung and Traub (J. ACM 643–651, 1974) for constructing multipoint optimal iterations without memory. We second present another optimal eighth-order class based on the King’s fourth-order family and the first attained class. To support the underlying theory developed in this work, we examine some methods of the proposed classes by comparison with some of the existing optimal eighth-order methods in literature. Numerical experience suggests that the new classes would be valuable alternatives for solving nonlinear equations.     

Effect of “Magnetized Water” on Size of Nickel Oxide Nanoparticles and their Catalytic Properties in Co2 Reforming of Methane

Theoretical and Experimental Chemistry - It was shown that the particle size of NiO nanoparticles has been controlled through the homogeneous precipitation process by using “magnetized...     

Synthesis and application of a novel magnetic nanosorbent for determination of trace Cd(II), Ni(II), Pb(II), and Zn(II) in environmental samples

In this work for the first time, Fe₃O₄@SiO₂ core–shell nanoparticles functionalized with isatin groups as a magnetic nanosorbent was applied for the simultaneous extraction of trace amounts of cadmium(II), nickel(II), lead(II), and zinc(II). The characterization of this nanosorbent was studied using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffraction, vibrating sample magnetometer and thermogravimetric analysis. The effect of several factors such as pH, amount of sorbent, extraction time, type and volume of the eluent, sample volume, sorption capacity, and potentially interfering ions was investigated. In the selected conditions, it was observed that the limits of detection were 0.11 ng mL^?1 for Cd(II), 0.28 ng mL^?1 for Ni(II), 0.47 ng mL^?1 for Pb(II), and 0.21 ng mL^?1 for Zn(II), and the maximum sorption capacity of this suggested magnetic nanosorbent was 120, 112, 100, and 100 mg g^?1 for Cd(II), Ni(II), Pb(II), and Zn(II), respectively. Also, the precision of the method (RSD%) for ten replicate measurements was found 2.5, 2.5, 2.8, and 3.1%, for Cd(II), Ni(II), Pb(II), and Zn(II) ions, respectively. Finally, the suggested procedure was applied for determination of cadmium(II), nickel(II), lead(II), and zinc(II) at trace levels in different water and agricultural products with satisfactory results.     

Preparation of polyphenylsulfone/graphene nanocomposite membrane for the pervaporation separation of cumene from water

Polyphenylsulfone (PPSU) was applied for the first time in the hydrophobic PV process. Nanocomposite membranes of PPSU/graphene (Gr) nanosheets were prepared and used to separate isopropyl benzene (cumene) from water via pervaporation (PV). Analysis of the mechanical properties of the membranes showed that the tensile strength and Young's modulus had an increasing trend with the incorporation of Gr into PPSU. The water contact angle of the membranes had a rising trend with the addition of Gr, confirming the improved hydrophobicity of membranes. In the PV experiments, the membrane containing 3.5 wt% Gr provided the highest separation factor, which was 4.5-fold as much as that of the neat PPSU membrane. Cumene separation from water by the PPSU/3.5 wt% Gr membrane was associated with the total flux of 132.73 gMH, the separation factor of 1566.36, and the PSI of 208,124.8 gMH.     

Determination of hydroxylamine using a carbon paste electrode modified with graphene oxide nano sheets

A carbon paste electrode that was chemically modified with 3-(4'-amino-3'-hydroxy-biphenyl-4-yl)-acrylic acid (3,4-AA) was used as a selective electrochemical sensor for the detection of hydroxylamine. Cyclic voltammetry (CV), choronoamperometry (CHA) and square wave voltammetry (SWV) were used to investigate oxidation of hydroxylamine in aqueous solution. Under optimized concentration the electrocatalytic oxidation current peak for hydroxylamine increased linearly with concentration in the range of 0.025–10.0 μM. The detection limits for hydroxylamine was 0.012 μM. Finally, the modified electrode was applied to detection hydroxylamine in water samples.     

Headspace solid-phase microextraction of menthol using a sol–gel titania-based coating along with multiwalled carbon nanotubes on the surface of stainless steel fiber

Sol–gel coating technology for the preparation of solid-phase microextraction fibers involves a single-step procedure and allows for in situ creation of chemically bonded coatings which are characterized by high thermal and solvent stabilities. A novel titania sol–gel coating was prepared for the first time on a stainless steel fiber and applied for the headspace solid-phase microextraction (HS-SPME) of menthol with gas chromatography and flame ionization detection. Important parameters influencing the efficiency of SPME process, such as extraction time, extraction temperature and ionic strength, were optimized by central composite design. An extraction time of 40 min at 60 °C gave maximum extraction efficiency, when NaCl (10% w/v) was added to the aqueous sample. The analytical characteristics of the proposed method were comparable with other reported fibers. Under optimized conditions, the linearity was between 0.05 and 100 µg mL^??1. The relative standard deviations (RSDs) determined at 0.5 µg mL^??1 concentration level (n?=?5) were as follows: intra-day RSD 7.26%; inter-day RSD 10.87%; fiber-to-fiber RSD 9.05%. The relative recoveries determined after spiking a mint distillate sample at three concentration levels from 0.067 to 50.0 µg mL^??1 varied from 86 to 102%. The proposed method was successfully applied for the analysis of menthol in peppermint samples.     

Genetic algorithm optimization for finned channel performance

Compared to a smooth channel,a finned channel provides a higher heat transfer coefficient;increasing the fin height enhances the heat transfer.However,this heat transfer enhancement is associated with an increase in the pressure drop.This leads to an increased pumping power requirement so that one may seek an optimum design for such systems.The main goal of this paper is to define the exact location and size of fins in such a way that a minimal pressure drop coincides with an optimal heat transfer based on the genetic algorithm.Each fin arrangement is considered a solution to the problem (an individual for genetic algorithm).An initial population is generated randomly at the first step.Then the algorithm has been searched among these solutions and made new solutions iteratively by its functions to find an optimum design as reported in this article.