Solid Transport Research Articles

(Invited) A Formalism Relating the Relative Humidity to the Proton Conductivity Mechanism of Membranes

The relationship between relative humidity of gas phase and proton conductivity in proton exchange membranes has been subject of extensive investigations [1],[2]. Herein, a theoretical framework is presented which describes proton transport in relation to stepwise equilibria that reflect the water uptake. In the proposed model, at first, the hydration process is treated as a stepwise equilibrium process, in agreement with experimental observations. Several hierarchical levels of structure evolve with increasing hydration. These levels are easily confirmed by the analysis of the electric response of perfluorinated based membranes by complex dielectric and conductivity spectra. Thus, a wide range of literature data on hydration of Nafion as a function of activity and temperature has been analyzed by means of the proposed model to extract chemical parameters diagnostic of the type of interactions characterizing the hydrophilic domains of membranes.These parameters, which are crucial in order to modulate the ion transport phenomena in ionomers, are then introduced into the model to describe the functional dependence of conductivity on water activity in gas phase. The treatment of proton conductivity is built on the approaches commonly adopted to describe transport in solids [3]. Key proton migration phenomena appropriate to the levels of the structural hierarchy are considered. The conductivity model is used to describe a set of conductivity vs. water uptake data as a function of temperature, with data taken to exceptionally low water contents. The formalism is then used to analyze a set of data for a perfluorosulfonic acid (PFSA) membrane as a function of hydration, temperature and polymer equivalent weight. The main advantage of the proposed framework is the possibility of a straightforward application to multiple membrane types based on the energetics of water uptake. Actually, the focus on chemical interactions allows to better correlate the effects of the morphology and relaxation events of the matrix to the proton migration phenomena of the membrane. Acknowledgements This work has received funding from: (a) the European Union’s Horizon 2020 research and innovation program under grant agreement 881603; (b) the project ‘Advanced Low-Platinum hierarchical Electrocatalysts for low-T fuel cells’ funded by EIT Raw Materials.

Designing Cathode Morphology for Materials with Solid Transport Limitation

Lithium manganese rich (LMR-NMC) material is a great candidate for next generation high energy density cathodes. It has high specific capacity, low cost, and decreased usage of Cobalt. However, these materials display poor rate capabilities attributed in part due to low lithium diffusion in cathode particle. The LMR-NMC cathode particles (size ~ 5 to 15 microns) are agglomeration of nanoscale primary particles. In this work, we focus on the link between morphology and performance. There are two characteristic diffusion lengths associated with the morphology of LMR-NMC. The diffusion length associated with primary particle radius and the diffusion length associated with the agglomeration of primary particles. The agglomerate diffusion length varies significantly with how the primary particles agglomerate. Presence of intra-agglomerate closed pores results in higher agglomerate diffusion length compared to open and well dispersed arrangement of primary particles. The electrochemical performance is better with smaller primary and agglomerate diffusion lengths. Tailoring the synthesis of cathode particles to obtain the desired diffusion characteristics is promising avenue to optimize the performance of LMR-NMC cathode materials. Figure 1

Population balance modeling of unstirred cooling crystallization on an integrated belt filter

The successive unit operations of cooling crystallization, cake filtration and contact drying are joined in one apparatus, the modular integrated belt filter, for small-scale downstream processing. This modular equipment offers high flexibility without external solid transport. After prior studies on equipment setup and functionality, this contribution focuses on understanding and influencing unstirred cooling crystallization in small layers with the aid of population balance modeling.An unstirred cooling crystallization is dominated by sedimentation effects. Thus, particle size distributions (PSD) are modeled for discrete spatial compartments based on orthogonal collocation on finite elements. Model validation regarding temperature profile and yield is conducted for two material systems featuring high (sucrose/water) and low viscosity (ascorbic acid/water). With a high impact on sedimentation, viscosity influences product quantity (yield) and quality (PSD). For both material systems, the effects of operating parameters on yield and PSD are determined through a parameter study based on surrogate models to derive optimal operating conditions.

Optimization of municipal solid waste transportation in the State of Paraná: rethinking the location of landfills based on mathematical modeling

RESUMO Neste trabalho foram utilizados, conjuntamente, os conceitos de particionamento territorial e localização de instalações para a otimização da rede de aterros sanitários do Estado do Paraná. Isso porque a solução adotada atualmente apresenta uma série de deficiências, incluindo o não atendimento total da demanda, o número excessivo de pequenos locais e diversos consórcios não contíguos, que resultam em maiores custos de transporte e menor eficiência de escala. O objetivo desta pesquisa é otimizar o particionamento territorial para o Estado do Paraná com relação aos aterros sanitários definindo um número adequado de lugares capaz de atender à demanda e que minimize as distâncias a serem percorridas dos pontos de geração do lixo até o descarte. Para isso, foram desenvolvidas simulações em função do custo de transporte rodoviário dos resíduos, em que foram considerados os locais dos 171 aterros operacionais existentes no Estado. Os resultados mostraram a necessidade de se alterarem algumas das capacidades das áreas de descarte existentes, além de se adicionarem 25 novas áreas para atender integralmente à demanda. Com isso, o gasto com transporte seria reduzido em cerca de 80% e o custo total, que inclui novas construções, ficaria reduzido em 57%, acarretando redução de gastos, além do aprimoramento na prestação do serviço e da atenuação do impacto ambiental.

Cloud-Edge-Terminal-Based Synchronized Decision-Making and Control System for Municipal Solid Waste Collection and Transportation

Due to dynamics caused by factors such as random collection and transportation requirements, vehicle failures, and traffic jams, it is difficult to implement regular waste collection and transportation schemes effectively. A challenge for the stable operation of the municipal solid waste collection and transportation (MSWCT) system is how to obtain the whole process data in real time, dynamically judge the process control requirements, and effectively promote the synchronization operation between multiple systems. Based on this situation, this study proposes a cloud-edge-terminal-based synchronization decision-making and control system for MSWCT. First, smart terminals and edge computing devices are deployed at key nodes of MSWCT for real-time collection and edge computing analysis of the whole process data. Second, we propose a collaborative analysis and distributed decision-making method based on the cloud-edge-terminal multi-level computing architecture. Finally, a “three-level and two-stage” synchronization decision-making mechanism for the MSWCT system is established, which enables the synchronization operation between various subsystems. With a real-world application case, the efficiency and effectiveness of the proposed decision-making and control system are evaluated based on real data of changes in fleet capacity and transportation costs.

Catalyst-scale investigation of polydispersity effect on thermophysical properties in a commercial-scale catalytic MTO fluidized bed reactor

The methanol-to-olefin (MTO) process is commercialized worldwide, yet the understanding of in-furnace phenomena is still lacking. Accordingly, this work explores the multiphase flow and thermochemical characteristics in a commercial-scale MTO fluidized bed reactor using a three-dimensional multiphase particle-in-cell model. After model validations, the intrinsic relationship of solid transportation and thermochemical properties is elucidated together with the study of the polydispersity effect on reactor performance. The non-uniform gas-solid distribution in the reactor demonstrates the turbulent fluidization regime. Heat transfer coefficients (HTCs) of about 300 and 200 W/(m2·K) are observed in the medium and upper regions, respectively. The small velocity, particle Reynolds number, temperature, and HTC correspond to those large-size catalysts in the dense region where particles are nearly close packing with a large solid volume fraction. Increasing particle size distribution (PSD) width increases the catalyst HTCs and the mass fraction of C2H4, promoting reactor performance. Besides, increasing the PSD width enlarges gas viscosity, gas specific heat capacity, and gas thermal conductivity but decreases gas density.

Significant Anharmonicity of Thermal Transport in Amorphous Silica at High Temperature

The anharmonicity of thermal transport in amorphous solids is underappreciated and inadequately understood, although considerable attention is paid to that of crystals. Herein, the anharmonic effects on the heat conduction of amorphous silica are investigated by combining the normal mode decomposition method with the Wigner transport equation. The existence of significant anharmonicity in amorphous silica, including temperature‐dependent linewidths and frequency shifts of the vibrational modes, is demonstrated. By considering the anharmonic effects, the predicted temperature dependence of thermal conductivities at high temperatures agrees well with the increasing trend observed in experiments. The underlying mechanisms are further revealed. The anharmonic frequency shifts notably affect the strength of coupling between pairs of vibrational modes and dictate the positive temperature dependence, whereas the increasing linewidths with increasing temperature are of minor importance. This work contributes to the understanding of the anharmonicity of thermal vibrations and heat conduction in amorphous materials.

The Ubiquitous Memristive Response in Solids

Basic ingredients universally available in the carrier transport of conductive solids are proved to be sufficient (not necessary) conditions for the formation of memory while symmetry, or the lack of it, plays a decisive role in the nature of this response. It suffices that the input driving frequency is of the order of the inverse relaxation time and that the nonequilibrium carrier densities are in the order of the quasi-equilibrium ones. Thus, memristive response with ON and OFF states at zero voltage, Type I, and vanishing ON– OFF ratio, Type II, arise naturally according to simple symmetry constraints and are contrasted here in a fully analytical picture. Figures of merit for the conductance and the robustness of the memory response are presented in the form of concise correlations between general intrinsic microscopic parameters such as relaxation times, activation energies, and efficiencies with external drives: voltage pulses, temperature, and illumination. Explicit analytical expressions unveil the mimicry of inductive- and capacitive-like leaning impedances without the need of relaxing the interpretation of flux that has been used for more stringent definitions of memristors.

New Solution Approaches for Multi-Objective Solid Transportation Problem Using Some Aggregation Operators

A solid transportation problem emerges when the decision variables are represented by three items: the source, the destination, and the mode of transport. In applications, the STP generally requires considering multiple objectives such as cost minimization, time minimization, security level maximization, etc. In this way, a multi-objective solid transportation problem arises. This paper deals with the solution of the problem and analyzes the effect of several important fuzzy aggregation operators on the solution of the problem. In this context, the most commonly used aggregation operators are investigated for this problem. To explain the solution approach, a numerical example from the literature is given and a Pareto-optimal solution set is provided to offer the decision-maker. Furthermore, graphical comparisons and sensitivity analysis are presented with the solution obtained.

Fixed-charge solid transportation problem with budget constraints based on carbon emission in neutrosophic environment

This paper is to integrate among solid transportation problem, budget constraints and carbon emission with probable maximum profit. The range of air pollution and climate change are effected by \({\text {CO}_2}\) gas emission and other greenhouse gases from myriad transportation systems. Henceforth, our target is to minimize carbon emission for pollution-free environment. Transportation system with single objective is hardly applicable to the situation with more than one criterion. Therefore multi-objective decision making is incorporated for designing real-life transportation problem. Due to time pressure, data limitation, lack of information or measurement errors in practical problems, there exist some hesitations. Based on the fact, decision maker considers indeterminacy in the designed problems. To overcome such hesitancy of occurrence and non-occurrence in fuzzy and intuitionistic fuzzy, neutrosophic set is very important and suitable to accommodate such general structure of problems. Therefore neutrosophic environment with neutrosophic linear programming, fuzzy programming and global criterion method is utilized here to find the compromise solution of the multi-objective transportation problem. Thereafter, the performance of the considered model is useful by evaluating a numerical example, and then the derived results are compared. Finally sensitivity analysis and conclusions with upcoming works of this research are stated hereafter.

Evidence and Implications of Hydrological and Climatic Change in the Reno and Lamone River Basins and Related Coastal Areas (Emilia-Romagna, Northern Italy) over the Last Century

Climate change and human activities have consequences on coastal areas as they affect hydrological processes in the related river basins. The riverine sediment supply to the beaches of the Emilia-Romagna coast, a highly urbanized area with high economic and naturalistic value, has been heavily impacted by human activities throughout the catchment, reducing solid transport to the coast and increasing the threat of coastal erosion and flooding. Despite the introduction of safeguard policies in the early 1980s and the consequent stoppage of such activities, the expected return in solid transport has not yet been reflected at the coast. To better understand the various processes acting at the river basin scale, we utilized empirical mode decomposition to analyze the variability in different parameters (river discharge, rainfall, air temperature, and sea level) from the headwaters to the coast of the Reno and Lamone rivers over the last century. The anthropogenic footprint, linked to the large-scale dimming/brightening phenomenon, is visible in the long-term trends. Moreover, natural signals with variable periodicity are evident and partially correlated with two major climate modes (North Atlantic Oscillation and Atlantic Multidecadal Oscillation). The coupled interactions among these processes, combined with the changes in land use and evapotranspiration during the last century, have resulted in the prolonged scarcity of river sediment supply and a long-term trend of erosion of the coastal area.

The applications of multiple route optimization heuristics and meta-heuristic algorithms to solid waste transportation: A case study in Turkey

The dense population and high solid waste production make it challenging to determine the optimal routes for garbage collection trucks in metropolitan cities. Moreover, incorrectly planned routes cause waste of fuel, time, and other resources in the municipal garbage collection process. Vehicle Routing Problem (VRP) is a combinatorial optimization problem that aims to find optimal routes for a certain number of vehicles that start from a depot, visit all customers, and return to the depot. This study aims to find the optimal routes that satisfy all the needs by considering the waste collection process of the Istanbul Umraniye district. Data on the currently used routes, daily tonnages, number of truck trips, and the number and locations of containers in the Umraniye district were obtained from the Umraniye municipality. We solve the route optimization problem of the Umraniye municipality with multiple heuristics and meta-heuristic algorithms like the nearest neighbor, savings, Christofides, simulated annealing, greedy descent, guided local search, and Tabu Search algorithms. We show the examined heuristics and meta-heuristics can produce fast and feasible solutions to large-size real-life problems.

A bedload transport in shallow water model applied for sediment transport in open channel flows

This paper presents the numerical approximation of bedload sediment transport due to shallow layer flows. The hydrodynamical component is modelled by a 2D shallow water system and the morphodynamical component by a solid transport discharge formula that depends on the hydrodynamical variables. The coupled system can be written as a non-conservative hyperbolic system. To discretize it, first we consider a Non-Homogeneous Riemann Solver scheme as well as a variant based on the use of flux limiters. In order to develop second-order scheme, we use a MUSCL method incorporating slope limiters in the spatial approximation and a two-step Runge-Kutta method for time integration. The comparison between results based on the proposed scheme and analytical results shows good agreement..

Type-2 zigzag uncertain multi-objective fixed-charge solid transportation problem: time window vs. preservation technology

Type-2 zigzag uncertain multi-objective fixed-charge solid transportation problem: time window vs. preservation technology

A parametric neutrosophic model for the solid transportation problem

PurposeThis research attempts to present a solid transportation problem (STP) mechanism in uncertain and indeterminate contexts, allowing decision makers to select their acceptance, indeterminacy and untruth levels.Design/methodology/approachDue to the lack of reliable information, changeable economic circumstances, uncontrolled factors and especially variable conditions of available resources to adapt to the real situations, the authors are faced with a kind of uncertainty and indeterminacy in constraints and the nature of the parameters of STP. Therefore, an approach based on neutrosophic logic is offered to make it more applicable to real-world circumstances. In this study, the triangular neutrosophic numbers (TNNs) have been utilized to represent demand, transportation capacity, accessibility and cost. Then, the neutrosophic STP was converted into an interval programming problem with the help of the variation degree concept. Then, two simple linear programming models were extracted to obtain the lower and upper bounds of the optimal solution.FindingsThe results reveal that the new model is not complicated but more flexible and more relevant to real-world issues. In addition, it is evident that the suggested algorithm is effective and allows decision makers to specify their acceptance, indeterminacy and falsehood thresholds.Originality/valueUnder the transportation literature, there are several solutions for TP and STP in crisp, fuzzy set (FS) and intuitionistic fuzzy set (IFS) conditions. However, the STP has never been explored in connection with neutrosophic sets to the best of the authors’ knowledge. So, this work tries to fill this gap by coming up with a new way to solve this model using NSs.

Bioinspired Lubricated Slippery Magnetic Responsive Microplate Array for High Performance Multi‐Substance Transport

AbstractIn nature, many organisms have the ability to transport substances, such as bubbles, droplets, or solids, on demand to meet their survival needs. Inspired by these distinct behaviors, a variety of substance transport strategies have been developed for promising applications in microfluidics, microelectronics, and biomedicine. However, it is still challenging to achieve versatile multi‐substance (gas, liquid, and solid) transport. In this work, a triple‐biologically inspired lubricated slippery magnetic‐responsive microplate array (LS‐MMA) by integrating the characteristics of fish scales, Nepenthes peristome, and respiratory cilia is proposed for multi‐substance transport. Under the actuation of the moving magnetic field, the microplates bend and overlap sequentially to form a continuous slippery surface with large curvature. With the continuous motion of the slippery surface, active multi‐substance transport can be realized. The transport speed of the bubbles, droplets, and solid glass balls can reach ≈5, ≈14, and ≈80 mm s−1, respectively. By virtue of the lubricant's capillary sticking property to the substance, the LS‐MMA also realizes 3D on‐demand transport of bubbles and droplets. The LS‐MMA‐based multi‐substance transport strategy improves the applicability and flexibility of target manipulation and has a broad potential application in the fields of microchemical reactions and biomedical engineering.

Generalization on Entropy-Ruled Charge and Energy Transport for Organic Solids and Biomolecular Aggregates.

Herein, a generalized version of the entropy-ruled charge and energy transport mechanism for organic solids and biomolecular aggregates is presented. The effects of thermal disorder and electric field on electronic transport in molecular solids have been quantified by entropy, which eventually varies with respect to the typical disorder (static or dynamic). Based on our previous differential entropy (hs)-driven charge transport method, we explore the nonsteady carrier energy flux principle for soft matter systems from small organic solids to macrobiomolecular aggregates. Through this principle, the synergic nature of charge and energy transport in different organic systems is addressed. In this work, entropy is the key parameter to classify whether the carrier dynamics is in a nonsteady or steady state. Besides that, we also propose the formulation for unifying the hopping and band transport, which provides the relaxation time–hopping rate relation and the relaxation time–effective mass ratio. The calculated disorder drift time (or entropy-weighted carrier drift time) for hole transport in an alkyl-substituted triphenylamine (TPA) molecular device is 9.3 × 10–7 s, which illustrates nuclear dynamics-coupled charge transfer kinetics. The existence of nonequilibrium transport is anticipated while the carrier dynamics is in the nonsteady state, which is further examined from the rate of traversing potential in octupolar molecules. Our entropy-ruled Einstein model connects the adiabatic band and nonadiabatic hopping transport mechanisms. The logarithmic current density at different electric field-assisted site energy differences provides information about the typical transport (whether trap-free diffusion or trap-assisted recombination) in molecular devices, which reflects in the Navamani–Shockley diode equation.

Viscosity of disordered Dirac electrons

Rejuvenation of hydrodynamic transport in solids provides a new window to study collective motion of electrons, where electrons behave like a viscous fluid akin to classical liquids. Experimental observations of such exotic states have not been realized until recent years, and an on-going quest is to amplify the hydrodynamic effect in electron fluids. Here we investigate the hydrodynamic properties of Dirac electron fluid in graphene from a microscopic viewpoint, and elucidate a novel way to enhance electron hydrodynamics. In particular, we present strong evidence that the shear viscosity of Dirac electrons can be enhanced by frequent electron-hole collisions, through three distinct aspects: promoting electrons and holes around the Dirac point by disorder, creating electron-hole shared zeroth Landau level by external magnetic field, and inducing electron-hole excitations by dynamic deformation. We also study Hall viscosity, which is closely related to the geometric topology and exhibits quantum behavior analogous to Hall conductivity. Therefore, our work demonstrates the exotic landscape of hydrodynamic electronics in graphene, and presents experimentally relevant responses to quantify the effects of electronic viscosity.

In Situ Growth of Strained Matrix on CsPbI3 Perovskite Quantum Dots for Balanced Conductivity and Stability.

Their nanoscale size endows perovskite quantum dots (QDs) with processing flexibility and high tunability of optoelectronic properties. The vast surface area also provides an opportunity for ligand engineering to offer QDs extra protection, which however, will impede charge transport in the QD array. Currently, the surface treatments that can balance both stability and conductivity of the perovskite QD array remain a huge challenge. Here, we report in situ growth of an atomic guanidinium lead iodide perovskite matrix on CsPbI3 QDs. In addition to the effect of trap passivation, the matrix can also provide substantial surface strain to improve the QD phase stability. Meanwhile, the ultrathin matrix allows efficient coupling and charge transport in the QD solids. As a result, the CsPbI3 QD solar cells can achieve both superior device stability and performance. We believe the development of a multifunctional surface matrix will become one of the future research focuses in perovskite QD-based devices.

Transient studies of gas transport in porous solids using frequency response method – A conceptual study

The response of a system in a state of equilibrium to a specific perturbation provides information about the processes triggered inside the system. This principle is the basis of the presented measurement method: the frequency response (FR) analysis. A customized apparatus is available to investigate mass transport processes of gases in porous solids. “Conventional” evaluation approaches, such as the characteristic FR functions, can be applied along with the complementary combination of other trending techniques such as numerical simulation. An example of a model developed with COMSOL Multiphysics® is shown. The overview discussion of the mentioned method and how electrochemical impedance spectroscopy and the method of temporal analysis of products complement the FR method in the study of mass transfer in porous materials is presented in this work.