Simultaneous heavy paraffin dehydrogenation and hydrogenation of nitrobenzene in a linear alkyl benzene plant

In the current study, a novel thermally coupled reactor with radial-flow pattern named as Radial Flow-Coupling Reactor (RF-CR) is modeled for heavy paraffin dehydrogenation. In this novel structure, the cross-section area of the Radial Flow-Tubular Reactor is sliced into some subsections. The necessary heat for heavy paraffin dehydrogenation in the endothermic side is supplied by the catalytic nitrobenzene hydrogenation in the exothermic side. The results of modeling represent 12.4 tons per day enhancement in the olefin production rate in comparison with non-coupling configuration using the same catalyst loading and duty. Besides, aniline as an additional valuable product is produced ～17.45 tons per day in exothermic side of RF-CR.     

Conversion of syngas to liquid hydrocarbons via a sorption-enhanced dual bed reactor

Fischer–Tropsch synthesis (FTS) plays an important role in the production of clean liquid transportation fuels, chemicals, and other hydrocarbon products. This study proposes a novel dual bed configuration of FTS reactor in which Zeolite 4A, with the composition of Na₁₂ (Si₁₂Al₁₂O₄₈)?27H₂O, is considered as water adsorbent inside the first reactor. In the second converter, the heat of reaction is used to pre-heat the synthesis gas to the first bed. The simulation results show an enhancement in the gasoline production, a main decrease in undesirable product formation (CO₂ and CH₄), and a favorable temperature profile along the proposed concept rather than the conventional reactor. This paper shows how the concept of in-situ water adsorption is feasible and beneficial for dual bed FTS.     

The concept of control points in hybrid discontinuous Galerkin methods—Application to geometrically nonlinear crystal plasticity

A new concept for hybrid discontinuous Galerkin (DG) methods is presented: control points. These are defined on the interelement boundaries. The concept makes it possible to formulate element shape functions without nodes. Moreover, the theory is not restricted to certain element shapes. Furthermore, one can formulate the discrete model such that the displacement is either continuous or discontinuous at the control points. Classical continuous isoparametric elements are included as special case. As an additional new feature, a regularization technique for very high strain rate sensitivity exponents up to 1000 in finite single crystal viscoplasticity is presented and implemented into the new hybrid DG framework. In addition, the numerical linearization used in an earlier work is carried out analytically in this work. To the knowledge of the authors, this work presents the first hybrid DG implementation of geometrically nonlinear plasticity, here in the context of single crystal plasticity. The regularization method in combination with the DG formulations facilitates a very simple implementation leading to a numerically efficient, robust, and locking‐free model. Two examples are investigated: the deformation of a planar double slip single crystal exhibiting localization in the form of shear bands and an oligocrystal under uniaxial load.     

Multilayered optical OFDM for high spectral efficiency in visible light communication system

Photonic Network Communications - This paper presents two new schemes for improving the spectral efficiency of an optical orthogonal frequency-division multiplexing-based visible light...     

Blasting pattern optimization using gene expression programming and grasshopper optimization algorithm to minimise blast-induced ground vibrations

Engineering with Computers - Blast-induced ground vibration is considered as one of the most hazardous phenomena of mine blasting, which can even cause casualties and severe damages to the adjacent...     

Nested Augmentation of Rainfall Monitoring Network: Proposing a Hybrid Implementation of Block Kriging and Entropy Theory

One of the most influential environmental variables is rainfall which has significant effect on water resources management, agricultural development, hydrology, and climate change studies. Due to high spatiotemporal variability of rainfall, its monitoring network design can be considered as a useful tool to improve the efficiency of recorded rain gauge stations within the study area. In this study, a new methodology of augmentation of rain gauge network is developed using coupled Block Kriging (BK) and entropy theory methods. In the proposed method, a nested approach of a two-stage positioning of rain gauge stations has been demonstrated. In the first stage, large-scale or fast positioning was done in which the optimal number of candidate blocks was identified. Then, local scale or fine-tuned positioning was done in the second stage. In this stage, to develop the network, accurate locations of rain gauge stations in each block are determined. Besides the main point of this paper, the effect of two kriging estimators, BK and Ordinary Kriging (OK), on the developed network has been investigated and compared. The study area is the Namak Lake watershed with various climates and altitudes. To assess the performance of the optimal rainfall network, three diagnostics were utilized; spatial distribution of annual precipitation, Estimation Error Variance (EEV) maps and histograms. Based on the results, 30 (more than 30% percent of the current stations) rain gauge stations have been proposed scattered over the watershed. Evaluation of the results has shown that the augmented rain gauge network proposed by the BK method outperformed dramatically that of the OK method. EEV maps and also statistical analysis of EEV values confirms the EEV value reduction of almost 25% in augmented network, as well.

     

Electrokinetic dewatering of Turkish glass sand plant tailings

In this study, the dewatering of glass sand plant tailings from Mersin, Turkey was investigated using an electrokinetic technique. The particle size (d(80)) of the solid waste material tested was less than 0.020 mm and consisted mainly of silica, orthoclase, alumina, potassium and iron oxides. In current plant practice, Larox high-pressure filters are used to produce a filter cake containing 22-25% moisture. As an alternative, a laboratory-scale dewatering pond using an electrokinetic technique was designed and a final product (cake) containing 34% moisture was obtained after 24h treatment using 14.6 V direct current applied for 40 min. When the treatment continued up to 48 h, a firm-to-hard cake was produced.     

Development of a technology orientated programming system for industrial robots

The disassembly of used goods is characterized by strongly varying quantities and a wide range of different kinds and states of products. Furthermore, the requirements of a disassembly system are determined by the disassembly object, by the process as well as by the disassembly system itself. As a result of the high labor costs in industrial countries and the huge amount of used goods, an automated disassembly is favored for the industrial disassembly. New methods for the programming of industrial robots have to be developed because the costs for a programming of small lot sizes are a key factor of the economic efficiency of small and medium sized enterprises (SME). In this paper an off-line programming environment for programming of industrial robots in the field of automated disassembly is presented. The exemplary implementation is realized at a pilot disassembly system, which was built up at the Institut für Werkzeugmaschinen und Fabrikbetrieb (IWF) of the Technische Universität Berlin.     

CFD simulation and experimental study of liquid flow mal-distribution through the randomly trickle bed reactors

A numerical model for liquid mal-distribution in randomly trickle bed reactors has been investigated and the results are compared with the experimental data. A CFD model based on the three-phase Eulerian approach is developed and a two-fluid model is utilized to perform the inter-phase momentum exchanges. Furthermore, radial distribution of the bed porosity is considered adjacent to the reactor wall. Two different types of liquid inlet distributors have been used in order to study the accuracy of the CFD model. To validate the CFD model, the simulation results are compared with the experimental data and the results from the porous media concept in which the permeability model has been applied to implement the inter-phase momentum exchange. Experimental results have been obtained on an industrial trilobe catalyst under a trickling flow regime in a pilot scale reactor setup. Co-current liquid and gas streams have entered to the reactor through a mono or multi orifice distributor. Results of the developed CFD model have found more accurate than that of the porous media concept when compared with the experimental data.     

Fano-Like Resonance from Disorder Correlation in Vacancy-Doped Photonic Crystals

By preparing colloidal crystals with random missing scatterers, crystals are created where disorder is embodied as vacancies in an otherwise perfect lattice. In this special system, there is a critical defect concentration where light propagation undergoes a transition from an all but perfect reflector (for the spectral range defined by the Bragg condition), to a metamaterial exhibiting an enhanced transmission phenomenon. It is shown that this behavior can be phenomenologically described in terms of Fano-like resonances. The results show that the Fano's parameter q experiences a sign change signaling the transition from a perfect crystal exhibiting a reflectance Bragg peak, through a state where background scattering is maximum and Bragg reflectance reaches a minimum to a point where the system reenters a low scattering state recovering ordinary Bragg diffraction. A simple dipolar model considering the correlation between scatterers and vacancies is proposed and the reported evolution of the Fano-like scattering is explained in terms of the emerging covariance between the optical paths and polarizabilities and the effect of field enhancement in photonic crystal (PhC) defects.