We compare evolutionary algorithms with minima hopping for global optimization in the field of cluster structure prediction. introduce a new average offspring recombination operator and it previously used operators. Minima is improved softening method stronger feedback mechanism. Test systems are atomic clusters Lennard-Jones interaction as well silicon gold described by force fields. The found to be well-suited all these homoatomic problems. algorithm more efficient compact symmetric ground...

The Bell-Evans-Polanyi principle that is valid for a chemical reaction proceeds along the coordinate over transition state extended to molecular dynamics trajectories in general do not cross dividing surface between initial and final local minima at exact state. Our states low energy are more likely into basin of attraction minimum than high trajectories. In context global optimization schemes based on our implies using have an only somewhat higher necessary overcome barriers lead fastest...

Abstract Liquid–solid fluid dynamics has been investigated in a 6‐in. (0.15 m) “cold‐flow” circulating fluidized bed riser using non‐invasive flow monitoring methods. Gamma‐ray computed tomography (CT) was used to measure the time‐averaged cross‐sectional solids volume fraction distributions at several elevations. The mean and “fluctuating” velocity fields were quantified computer‐automated radioactive particle tracking (CARPT) technique. experimental equipment, protocol of implementation,...

Ni enhances CNT production via Fe-based catalysts, with 40Fe–5Ni yielding 5.80 gC per g metal, outperforming pure Fe as a catalyst. DFT supports experimental findings by revealing stronger carbon binding, thus enabling more efficient production.

The trend toward environmentally benign processing has resulted in novel chemistries and new reactor types. For alkylation of both aromatics linear paraffins, with solid acid catalysts, liquid−solid risers are one the types considered. As fluid dynamics is largely unknown, it been investigated this work a 6-in.- (15-cm-) diameter "cold-flow" circulating fluidized-bed riser using noninvasive methods. time-averaged solids holdup distribution determined by γ-ray computed tomography (CT)....

Even though many experimental investigations are reported on this subject of liquid velocity patterns in bubble columns, most the work is restricted to measurements at near wall regions, columns without internals, and low dispersed phase hold‐ups. In present work, a non‐invasive radioactive particle tracking technique was employed quantify hydrodynamic parameters 120 mm diameter column with, vertical rod using air/water system as working fluids. The superficial air velocities cover wide...

The accuracy of the fundamental properties energy landscape silicon systems obtained from density functional theory with various exchange-correlation functionals, a tight binding scheme, and force fields is studied. Depending on application, quantum Monte Carlo or results serve as quasiexact reference values. In addition to well-known methods for geometric ground states metastable configurations we find that give similar transition thus good overall description systems. On other hand, very...

Optimizations of atomic positions belong to the most commonly performed tasks in electronic structure calculations. Many simulations like global minimum searches or characterizations chemical reactions require performing hundreds thousands minimizations saddle computations. To automatize these tasks, optimization algorithms must not only be efficient but also very reliable. Unfortunately, computational noise forces and energies is inherent codes. This poses a severe problem stability methods...

A liquid−solid circulating fluidized bed is a potential reactor of interest in variety industrial processes, such as petroleum refining, and the synthesis fine chemicals, petrochemicals, foodstuffs. Rapid deactivation solid catalyst these processes necessitates regeneration recirculation solids into riser section which principal reaction accomplished. In this study we show that computer-automated radioactive particle tracking (CARPT) can be used to obtain velocity patterns backflow exists at...

Abstract The effect of inclination angle a packed bed on its corresponding gas–liquid flow segregation and liquid saturation spatial distribution was measured in co‐current descending flows for varying inclinations fluid velocities, simulated using two‐phase Eulerian computational dynamics framework (CFD) adapted from trickle‐bed vertical configuration based the porous media concept. model predictions were validated with our own experimental data obtained electrical capacitance tomography....

Abstract Liquid phase mixing is a phenomenon that results mainly due to convective and turbulent flow fields, which are generated by hydrodynamic interactions between the gas liquid phases within continuous co‐current upflow bubble column reactor. The extent of usually quantified through time, or axial dispersion coefficient. In present work, computational fluid dynamics (CFD) simulations for RTD in (with without internals) performed using OpenFOAM 2.3.1. superficial velocities were 0.014,...

Abstract Radioactive particle tracking (RPT) is one of the most widely used non‐intrusive velocimetry technique for multiphase reactors. The large volume interrogation and presence internals limit application RPT in large‐scale real‐world systems. main challenge lies having fast reconstruction algorithms applicable to conventional (i.e., bubble columns, fluidized beds, etc.) as well new vessels. In this contribution, a methodology proposed based on machine learning. Three machine‐learning...

Abstract Dynamics of segregation and fluidization unary particles binary mixtures in a cylindrical fluidized bed is investigated using temporally– spatially–resolved measurements solids volume fraction ( α s ) performed Electrical Capacitance Tomography (ECT). Through the comparison with high‐speed imaging, we have shown that ECT can be used to measure behavior beds quantitatively. been further quantify effects mixture composition, particle–diameter ratio, superficial gas velocity on...

Abstract Including internals in bubble columns is known to enhance the gas holdup. In this paper, a method achieve objective substantially has been proposed via use of vibrating helical spring internals. Experimental observations on effect such as springs holdup are presented. Effects superficial velocity, H / D ratio (height static liquid column diameter ratio), volume fraction springs, and thickness wires hydrodynamics parameters studied. Increase up 135% observed by using compared without...