Mixed Configuration Research Articles

Potassium recovery from vinasse by integrated electrodialysis – precipitation process: Effect of the electrolyte solutions

Abstract This study aimed to investigate the influence of four different electrolyte solutions (Na2SO4, MgSO4, K2SO4, and NH4NO3) on electrodialysis (ED) performance for vinasse desalination and nutrient recovery, especially of potassium, for agricultural purposes. The experiments were carried out using a mixed configuration of ion exchange membranes, which utilized a monoselective cationic membrane between the central and cathode concentrated compartments and the other non-monoselective membranes. The solution performance was mainly evaluated in terms of energy efficiency as well as nutrient removal and recovery (Ca2+, K+, and Mg2+). The chemical equilibrium model Visual MINTEQ was used to estimate the struvite and K-struvite precipitation from the cathode concentrated stream. The MgSO4 and NH4NO3 solutions provided the best conditions for vinasse desalting and subsequent nutrient recovery. When MgSO4 and NH4NO3 were used as electrolyte solutions, 4.4 and 3.9 kg of K-struvite and 0 and 7.3 kg of struvite per m3 of treated vinasse were estimated to be produced, respectively. The desalted vinasse, with a lower potassium content, can be applied via fertigation at higher rates. Therefore, ED is a promising alternative method for vinasse treatment, reducing the environmental impacts associated with its disposal. Moreover, the integration of ED with precipitation has great potential to produce valuable fertilizer.

End-to-end latency characterization of task communication models for automotive systems

Different communication models have been historically adopted in the automotive domain for allowing concurrent tasks to coordinate, interact and synchronize on a shared memory system for implementing complex functions, while ensuring data consistency and/or time determinism. To this extent, most automotive OSs provide inter-task communication and synchronization mechanisms based upon memory-sharing paradigms, where variables modified by one task may be concurrently accessed also by other tasks. A so-called “effect chain” is created when the effect of an initial event is propagated to an actuation signal through sequences of tasks writing/reading shared variables. The responsiveness, performance and stability of the control algorithms of an automotive application typically depend on the propagation delays of selected effect chains. Depending on the communication model adopted, the propagation delay of an effect chain may significantly vary, as may be the resulting overhead and memory footprint. In this paper, we explore the trade-offs between three communication models that are widely adopted for industrial automotive systems, namely, Explicit, Implicit, and Logical Execution Time (LET). A timing and schedulability analysis is provided for tasks scheduled following a mixed preemptive configuration, as specified in the AUTOSAR model. An end-to-end latency characterization is then proposed, deriving different latency metrics for effect chains under each one of the considered models. The results are compared against an industrial case study consisting of an automotive engine control system.

Reliability and Sensitivity assessment of a Thermal power plant using Boolean function technique

The aim of aforementioned paper is to investigate the terminal reliability, mean time to failure and sensitivity analysis for a thermal power plant based on minimizing Boolean expression approach. A thermal power plant be expressed by four major subsystems namely conveyer, boiler, turbine and generator arranged in mixed configuration. Conveyer and boiler both individually have two units in parallel redundancy. Throughout the task thermal power plant may work in basically three different states namely good, degraded and failed state. The various results regarding reliability, mean time to failure (MTTF) and sensitivity analysis are authenticated with the help of graphs.

Transient performance of the mixed flow and radial flow variable geometry turbines for an automotive turbocharger

In our previous paper, the steady-state test results of a mixed flow turbine with variable nozzle vanes for a turbocharger are reported. In this paper, the transient response of the same mixed flow turbine along with that of a similarly sized radial flow turbine is presented. The turbine size is suitable for handling the flow capacity of the diesel engines with swept volume up to 1.5 L. The previous experimental test set up is modified by adding a quick-release valve – actuation system before the turbine inlet to obtain a transient response. The radial and mixed flow turbines are tested for different turbine inlet pressures and for various opening positions of the nozzle vanes while matching the turbine mass flow parameters between radial and mixed flow turbines. Typically at nozzle vane openings corresponding to 50% mass flow parameter and 1.5 bar (abs) pressure at the inlet to the turbine, the transient response time for the turbine with mixed flow variable nozzle vanes configuration is about 0.770 s, as compared to 0.858 s for the turbine with radial flow variable nozzle vanes configuration.

MORPHOLOGICAL CARTOGRAPHY OF BLOCKS AND LOTS IN NEIGHBORHOODS OF THE JUÍNA MUNICIPALITY, MATO GROSSO STATE, BRAZIL

This study aimed to identify and analyze the morphological cartography and population density of blocks and lots of the city of Juína-MT. Data were collected in the neighborhoods “Module 1” and “Module 6” with the aid of topographic precision techniques and tools. Subsequently, the elements found were processed by an engineering software, which generated topographic plans to diagnose the topology of the respective lots and blocks. Results showed that blocks and lots of the Module 1 neighborhood presented orthogonal shapes with population density of 28 inhabitants per hectare, and the Module 6 neighborhood presented blocks and lots with orthogonal and non-orthogonal mixed configurations with population density of more than 30 inhabitants per hectare.

Adsorption Behavior of the Hydroxyl Radical and Its Effects on Monolayer MoS2.

Based on first-principles density functional theory calculations, we investigated a modified routine using hydroxyl adsorption that recently demonstrated the controlled growth of MoS2 monolayers. The new growth approach impedes the deposition of a second MoS2 layer; however, the hydroxyl adsorption and its effects have been mostly unexplored. Through this study, we first explored the adsorption behaviors of the hydroxyl radical (OH) on monolayer MoS2 and briefly discussed its effects on the stability and electronic structure. Monolayer MoS2 repels charged OH–, whereas the adsorption of the neutral OH radical is energetically favorable; the corresponding adsorption energies are 0.09 eV and −1.35 eV, respectively. The diffusion barrier of the OH radical on MoS2 is 0.52 eV, indicating that the molecule can quickly diffuse. Next, the study demonstrated that for multiple OH adsorptions, a concerted reaction including OH dissociation and H2O formation is more energetically favorable than the adsorption of two OH molecules by 2.50 eV, which in turn results in a mixed adsorption configuration of O and OH. In addition, we revealed that the OH adsorption creates a mid-gap state and facilitates the reconstruction of the MoS2 edge.

Effect of ITO electrode patterning on the properties of organic heterostructures based on non-fullerene acceptor prepared by MAPLE

This paper presents some studies on the organic heterostructures realized by Matrix Assisted Pulsed Laser Evaporation in both bi-layer and mixed layer configurations on glass substrates covered by flat or nano-patterned ITO. The donor, a star-shaped arylenevinylene compound, 4,4′,4″-tris[(4′-diphenylamino) styryl] triphenylamine, and acceptor, a non-fullerene compound, N,N′-bis-(1-dodecyl)perylene-3,4,9,10 tetracarboxylic diimide, were blended in three weight ratios: 1:2, 1:3 and 1:4.A grating of cylindrical pillars with a periodicity of 1.1 μm has been developed by UV-Nanoimprint Lithography in a polymer layer. The shape of the nanostructures changed to cone trunk by the Pulsed Laser Deposition of ITO on this nanostructured surface.The effect of the nanostructures and composition on the optical and electrical properties of the heterostructures was analyzed.The nano-patterning affected both the UV–Vis transmission and photoluminescence through the multiple reflections inside the cavities and at interfaces and the particularities of the molecular arrangement. The patterning was preserved independently of composition, but the roughness increased with increasing acceptor amount.The I-V characteristics drawn at room temperature in dark revealed an ohmic contact behavior for all heterostructures. The nano-patterning had a similar effect on the current in the heterostructures with mixed layer (1:2) and stacked bi-layer.

Mixed configurations of tensor-multiscalar solitons and neutron stars

In the present paper we consider special classes of massive tensor-multi-scalar theories of gravity whose target space metric admits Killing field(s) with a periodic flow. For such tensor-multi-scalar theories we show that there exist mixed configurations of tenor-multi-scalar solitons and relativistic (neutron) stars. The influence of the curvature of the target space on the structure of the mixed configurations is studied for two explicit scalar-tensor theories. The stability of the obtained compact objects is examined and it turns out that the stability region spans to larger central energy densities and central values of the scalar field compared to the pure neutron stars or the pure tensor-multi-scalar solitons.

Mixed star-plus-wormhole systems with a complex scalar field

We study compact mixed configurations with a nontrivial wormholelike spacetime topology supported by a complex ghost scalar field with a quartic self-interaction and a polytropic fluid. The latter is modeled by a relativistic barotropic equation of state that can approximately describe more or less realistic matter. For such systems, we find regular asymptotically flat equilibrium solutions describing localized configurations in which the fluid is concentrated in a finite-size region. The solutions obtained describe double-throat wormholes which are located outside the fluid (one can say that the fluid is hidden inside the region between the throats). Also, we consider the dependence of the total mass of the system on the central density of the fluid and demonstrate the existence of critical values of the central density at which the mass diverges. In this case all regular solutions possessing finite masses lie in the region between these critical values, and this region also contains a discontinuity in magnitudes of the central density where only physically unacceptable oscillating solutions do exist. Is shown that for some values of the central density of the fluid there can exist solutions describing systems whose fluid density and pressure maxima lie not at the center. This results in the fact that such systems possess two equators (local maxima of the metric function) resided symmetrically with respect to the center.

Water/methanol solutions characterized by liquid μ-jet XPS and DFT—The methanol hydration case

The advent of liquid μ-jet setups as proposed by Faubel and Winter – in conjunction with X-ray Photoemission Spectroscopy (XPS) – has opened up a large variety of experimental possibilities in the field of atomic and molecular physics. In this study, we present first results from a synchrotron-based XPS core level and valence band electron spectroscopy study on water (10-4 M aqueous NaCl solution) as well as a water/methanol mixture using the newly commissioned ALBA liquid μ-jet setup. The experimental results are compared with simulations from density functional theory (DFT) regarding the electronic structure of single molecules, pure molecular clusters, and mixed clusters configurations as well as previous experimental studies. We give a detailed interpretation of the core level and valence band spectra for the vapour and liquid phases of both sample systems. The resulting overall picture gives insight into the water/methanol concentrations of the vapour and liquid phases as well as into the local electronic structure of the pertinent molecular clusters under consideration, with a special emphasis on methanol as the simplest amphiphilic molecule capable of creating hydrogen bonds.

A one-dimensional full-range two-phase model to efficiently compute bifurcation diagrams in sub-cooled boiling flows in vertical heated tube

This paper presents a powerful numerical model to compute bifurcation diagrams in liquid-vapor two-phase fluid flows in vertical heated tube. This full range two-phase model is designed to deal with both single phase (purely liquid or purely vapor) and mixed liquid-vapor configurations that span all flow regimes (laminar and turbulent) in forced, mixed and natural convections. The originality of the proposed methodology is to faithfully integrate the implicit highly nonlinear system of governing equations along branches of steady-state solutions. This is performed by means of a continuation algorithm based on the Asymptotic Numerical Method supplemented with Automatic Differentiation. Then, linear stability analyses are performed at various points of interest, enabling to figure out stability limits within the parameter space in natural circulation configurations. Markedly, Hopf bifurcations that indicate limit-cycle occurrences are identified at low and medium void fractions, respectively, showing the added-value of the approach to track density-wave mechanisms and potential failure of standard application of Ledinegg stability criteria on such cases.

Forward Modeling of GPR Data by Unstaggered Finite Difference Frequency Domain (FDFD) Method: An Approach towards an Appropriate Numerical Scheme

Forward modeling of ground penetrating radar (GPR) is an important part to the inversion/modeling of the observed data. The aim of this study is to establish specific numerical schemes for forward modeling of GPR data by finite difference frequency domain (FDFD) method which were originally developed for seismic or finite difference time domain (FDTD) method. A total number of six modified and improved FDFD techniques have been used to discretize the two-dimensional (2D) transverse electric (TE)-mode scalar wave equation in order to find the suitable method for this. These techniques include five-point classical to nine-point mixed unstaggered-grid configurations. The numerical schemes for three unsplit perfectly matched layer (PML) for nine-point mixed unstaggered-grid configurations are also presented. The applicability of these techniques is tested by using the underground models of relative permittivity and conductivity for the two cases of homogeneous and 2-cross models. GPR shot gather data for these two models are also produced for this study. The relative reflection errors of the numerical schemes are also estimated for the homogeneous model to comprehend the appropriate method for the modeling. The algorithm for complex-frequency shifted PML (CFSPML) gives the least error in case of the forward modeling of the GPR data.

Synthesis, Structure and Properties of Poly(1-trimethylsilyl-1-propyne) Obtained with NbBr5- and TaBr5-Based Catalytic Systems

In this work, the polymerization of 1-trimethylsilyl-1-propyne [TMSP] using catalytic systems based on pentabromide Nb(V) and Ta(V) with organometallic cocatalysts Ph3Bi, Ph4Sn, Bu4Sn, Ph3SiH, and Et3SiH was investigated. The use of NbBr5-based catalytic systems has strongly marked cis-stereospecificity and gives highly cis-enriched poly(1-trimethylsilyl-1-propyne) [PTMSP] (content of cis-units above 70%), whereas the use of TaBr5-based catalytic systems leads to the formation of PTMSP with mixed cis-/trans-composition (content of cis-units from 50 to 65%).With increasing cis-content, solvent resistance of PTMSP increases significantly. PTMSP with a content of cis-units above 70% obtained on NbBr5-containing systems in cyclohexane acquires resistance to aliphatic and aromatic hydrocarbons, and cis-regular PTMSP obtained on NbBr5-based systems in toluene is totally insoluble in any of the organic solvents. The results of wide-angle X-ray diffraction indicate an increase in the packing density of the polymer during the transition from a mixed configuration to a cis-regular one. Durable PTMSP film membranes exhibit ultra-high permeability coefficients for individual gases (e.g., $${{P}_{{{{{\text{O}}}_{{\text{2}}}}}}}$$ = 8500–11000 barrer, $${{\alpha }_{{{{{\text{O}}}_{{\text{2}}}}{\text{/}}{{{\text{N}}}_{{\text{2}}}}}}}$$ = 1.5–1.9). According to the low-temperature Ar sorption, PTMSP synthesized with NbBr5- and TaBr5-based catalytic systems has high BET surface areas in the range of 870–1050 m2/g, high intrinsic microporosity, and higher gas permeability coefficients of PTMSP correlate with BET surface area growth.

Repeated localized impulsive loading on monolithic and multi-layered metallic plates

Abstract The objective of the current study is to numerically investigate the effect of repeated localized impulsive loading on the performance and dynamic plastic response of monolithic and multi-layered circular plate configurations made of either high- and low-strength aluminum or steel or a combination of these materials in the impulse range of 12.5–30 N s. For this, several numerical models were developed using ABAQUS/Explicit commercial FEM software via a FORTRAN subroutine VDLOAD in combination with the Johnson-Cook thermoviscoplastic constitutive relation, as well as the Johnson-Cook damage model. In order to validate the numerical models, the available experimental results on monolithic and multi-layered plate configurations under single localized load were used. Afterward, 18 different numerical models and 96 various cases including monolithic, double- and triple-layered plate configurations with an equivalent areal density subjected to five consecutive loads, were employed. The numerical simulation results indicated that a double-layered mixed configuration with a thin back steel layer and a thick front aluminum layer performs better compared to other configurations made of similar and dissimilar materials at higher impulses subjected to multiple impulsive loading, particularly while steel and aluminum materials have lower strength.

Effect of flow configuration on the performance of spiral-wound heat exchanger

The effects of flow configuration on the heat transfer performance of a spiral wound heat exchanger were experimentally investigated. The spiral-wound heat exchanger was made from stainless steel tubes of 6 mm outside diameter and consisted of 4 helical coils centrally connected in series, with a longitudinal and transverse pitch of 12 mm. Three air flow configurations were tested, namely axial, radial, and mixed axial-radial flows. The overall heat transfer coefficient was determined from the experimental data and the shell-side convection heat transfer coefficient was calculated from the tube-side convection heat transfer coefficient and the total thermal resistance. The measurements were conducted for tube-side Reynolds number in the range of 9000–10,000 (for water flow inside the tubes) and shell-side Reynolds number in the range of 500–6000 (for air flow outside the tubes based on maximum velocity). The results showed that the mixed axial-radial flow configuration has the highest heat transfer coefficient and pressure drop followed by the axial and radial flow configurations. Correlations of Nusselt number, Colburn-j factor, and friction factor were developed for the different flow configurations and a comparison with the Nusselt number correlations for heat transfer over bank of tubes was presented. The correlations are in good agreement with experimental data and has correlation coefficient in the range of 78–98%.

Time reversal applied to fault location in power networks: Pilot test results and analyses

This paper presents the results of a pilot test performed on a real medium voltage distribution network in Switzerland with the aim of assessing the performance of a fault location system relying on the Electromagnetic Time Reversal (EMTR) method. To the best of the Authors’ knowledge, this is the first time that the EMTR-based fault location technique is validated through live tests. The pilot network is a live radial medium voltage distribution feeder, which consists of 11.9-km long double-circuit lines operating at 18/60 kV and multiple 18-kV three-phase laterals. The branched lines are overhead lines, underground cables, or mixed configuration with lengths ranging from tens of meters to a few kilometers. The test involves solid- and resistive-type single-phase-to-ground fault occurrences triggered along one of the laterals when the network is operational. The fault location task is performed by a real-time industrial controller prototype that integrates the functions of fault detection, data acquisition, time-reversal processing and Electromagnetic Transients simulations. Concerning the methodological aspects, the EMTR Fault Current Signal Energy (FCSE) metric is used to determine the location of the fault. The obtained results show that the FCSE metric is capable of accurately identifying the faulty phase and the real fault location in all tested fault cases, with a location accuracy of less than 10 m.

Entanglement negativity in Galilean conformal field theories

We obtain the entanglement negativity for various bipartite zero and finite temperature pure and mixed state configurations in a class of $(1+1)$-dimensional Galilean conformal field theories. In this context we establish a construction for computing the entanglement negativity for such bipartite states involving a suitable replica technique. Our construction exactly reproduces certain universal features observed for entanglement negativity of corresponding states in relativistic $(1+1)$-dimensional conformal field theories.

Investigation of electrodialysis configurations for vinasse desalting and potassium recovery

This study aimed to investigate three different electrodialysis (ED) configurations using two distinct membranes, a monovalent ion selective membrane and a non-selective heterogeneous membrane. The configurations were evaluated in terms of efficiency of potassium recovery from vinasse and energy requirements. Moreover, the contribution of vinasse pretreatment by ultrafiltration was assessed. The results showed that ultrafiltration is important to prevent membrane fouling and save energy. Tests with only monovalent-selective membranes, only non-selective membranes and a mixed configuration (one cationic selective membrane and the others non-selective) were performed. The mixed ED configuration was able to recover 72% of potassium applying a current density of 60 A m−2, with the lowest energy consumption (9 kW h m−3) and the best current efficiency (54%). Therefore, the ED was proved to be an advantageous method for vinasse treatment, generating a concentrated solution that can be profitably used as fertilizer and a diluted effluent that could be used for biogas production or fertigation.

Influence of mixed and displacement air distribution systems' design on concentrations of micro-particles emitted from floor or generated by breathing

Particles deposited on surfaces and floors can be reintroduced into air through re-suspension; thus constituting a threat to humans’ health. The ventilation system configuration should reduce indoor air particle concentrations and ensure minimal deposition and re-deposition fractions over surfaces and floors. The purpose of this work is to compare the effectiveness of different mixed and displacement air distribution system configurations in removing re-suspended particles from indoor occupied space for two main scenarios of particle generation: floor emissions and particle generated at the breathing level. The performance was investigated using configurations with variable inlet/outlets sizes and locations by evaluating breathing level air quality. A computational fluid dynamics (CFD) model was developed to predict the flow field and particle transport in the space using ANSYS Fluent software. The model was validated by experimentation.Good agreement was achieved between the CFD and experimental values of planer normalized concentration at different heights with a maximum relative error in the order of 10%. This was followed by a parametric study conducted to determine the most influential design parameters in enhancing indoor air quality: the relative inlet/outlet location, the number of exhausts and the suction velocity. Mixed ventilation configuration with top supply and two floor return vents at walls’ middle (reversed displacement ventilation) presented the best performance in case of floor generation by creating an effective symmetrical suction covering the majority of floor area while DV provided the worst performance. Accordingly, recommendations on switching operation between displacement and mixed ventilation were provided in case of activities involving high floor resuspension as dusting and vacuuming.

Removal of Chromium from Aqueous Solution using Multilayer-Mixed (Reduction/Sorption) Bed from Iron Scrap and Nutshells

In this research removal of chromium from an aqueous solution by multilayer-mixed (reduction/sorption) bed via scrap iron as zero valent iron and charred nutshell (walnut shell) as adsorber were studied. Both batch and continuous system were conducted. The batch system reveals that the adsorption process was of favorable type. Three models were used to describe the adsorption process. Freundlich model is matching well to the data with (R2=0.975). In the continuous system , two sets of experimental were considered, the first set (multilayer bed) conducted by fixing the characteristics of the scrap iron bed (bed height 0.2 cm, particle size 500 µm) and varying the walnut shell parameters, the optimum value of this set recorded as (bed height 2.5 cm, particle size250µm). While for the second set of experimental after fixing the optimum values of the walnut shell bed and varying the scrap iron bed characteristics, the optimum values were (height 1cm, particle size 500µm as filling). Also, the Mixed bed configuration were studied by conducting the optimum conditions for the previous experiment. it was found that at any certain time the mixed layer offers the maximum efficiency of removal rather than the multi-layer bed.