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A mixed shop is a manufacturing infrastructure designed to process a mixture of a set of flow-shop jobs and a set of open-shop jobs. Mixed shops are in general much more complex to schedule than flow-shops and open-shops, and have been studied since the 1980's. We consider the three machine proportionate mixed shop problem denoted as M 3 | p r p t | C max , in which by "proportionate" each job has equal processing times on all three machines. Koulamas and Kyparisis (2015) [6] showed that the problem is solvable in polynomial time in some very special cases; for the non-solvable case, they proposed a 5/3-approximation algorithm. In this paper, we first present an improved 4/3-approximation algorithm and show that this ratio of 4/3 is asymptotically tight; when the largest job is a flow-shop job, we then present a fully polynomial-time approximation scheme (FPTAS). On the negative side, while the F 3 | p r p t | C max problem is polynomial-time solvable, we show an interesting hardness result that adding one open-shop job to the job set makes the problem NP-hard if this open-shop job is larger than any flow-shop job. We are able to design an FPTAS for this special case too. [ABSTRACT FROM AUTHOR]

Based on the Euler-Lagrange equation for ion density distribution in an inhomogeneous, charged, and hard-sphere fluid, a novel method is proposed to determine the interaction pressure between charged plates. The resulting expression is a sum of distinct physical contributions to the pressure, which involves different contributions to the single-particle direct correlation function. It can, therefore, be conveniently used in any density functional approach to facilitate analysis of the pressure components. In this study, the so-called fundamental measure theory (FMT)/weighted correlation approach (WCA) approach is applied to estimate both the hard-sphere and the electric residual contributions to the single-particle direct correlation function, upon the calculation of the ionic density profiles between charged plates. The results, against the Monte Carlo simulations, show that the FMT/WCA approach is superior to the typical FMT/mean spherical approximation approach of the density functional theory in predicting the interaction pressure between charged plates immersed in an electrolyte solution upon various conditions in the primitive model. The FMT/WCA approach can well capture the fine features of the pressure-separation dependence, to reproduce not only the shoulder shape and the weak attractions in monovalent electrolytes but also the strongly oscillatory behavior of pressure in divalent electrolytes where pronounced attractions are observed. In addition, it is found that the FMT/WCA approach even has an advantage over the anisotropic, hyper-netted chain approach in that it agrees with the Monte Carlo results to a very good extent with, however, much less computational effort. [ABSTRACT FROM AUTHOR]

Using an equivalent circuit model to characterize the constant-current part of a charging/discharging profile, a model is developed to estimate the state-of-health of lithium ion batteries. The model is an incremental capacity analysis-based model, which applies a capacity model to define the dependence of the state of charge on the open circuit voltage as the battery ages. It can be learning-free, with the parameters subject to certain constraints, and is able to give efficient and reliable estimates of the state-of-health for various lithium ion batteries at any aging status. When applied to a fresh LiFePO 4 cell, the state-of-health estimated by this model (learning-unrequired or learning-required) shows a close correspondence to the available measured data, with an absolute difference of 0.31% or 0.12% at most, even for significant temperature fluctuation. In addition, NASA battery datasets are employed to demonstrate the versatility and applicability of the model to different chemistries and cell designs. • An ICA-based model is proposed to estimate SOH of LIBs. • The ICA-based model can be learning-required or learning-unrequired. • This model can give reliable estimates of SOH for various LIBs at any aging status. • The accuracy of the model is validated by experimental results of LFP and NCA batteries. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a techno-economic study to seek the feasibility about the proposed system that integrating solar-assisted pressure-temperature swing adsorption (PTSA) into an 800MW e coal-fired power plant. Solar energy has the potential to supply thermal energy demand for carbon capture, which can avoid the energy consumption of the traditional method such as the steam extraction. The performance of the proposed system is largely affected by the climatic conditions and solar collector's types. The assessment criteria include carbon emission intensity (CEI), levelized cost of electricity (LCOE) and cost of CO 2 avoidance (COA). By the parametric analysis, the results show that CEI of the novel system with solar thermal collectors is approximately 2g/kWh lower than that of the referenced power plant with CO 2 adsorption capture. In addition, CEI of the novel system can be further decrease with the decline of desorption temperature, adsorption pressure and desorption pressure. For the sake of lower LCOE and COA, the prices of the power plant capacity, adsorbents and solar collectors should be reduced. Specifically, LCOE of the system with evacuated tube collector will be lower than that of the reference system with CO 2 capture as the price of solar field is lower than 46.08 USD/m2. Graphical abstract Image 1001 Highlights • A power plant with solar-assisted PTSA for CO 2 capture is proposed and studied. • Technical study is evaluated in terms of carbon emission intensity. • Economic evaluation is conducted in terms of LCOE and COA. • The proposed system is superior to other solar-assisted CO 2 capture methods. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The novel ventilation can separate carbon dioxide from indoor air and outdoor air. • The minimum separation work for capturing from 400 ppm air is about 20 kJ/mol. • The optimal second-law efficiencies range from 31.60% to 44.57% for 1000–3000 ppm. • Possibility for approaching negative carbon buildings has been explored. Abstract Abrupt climate change such as the loss of Arctic sea-ice area urgently needs negative emissions technologies. The potential application of direct air capture of carbon dioxide from indoor air and outdoor air in closed buildings or crowded places has been discussed in this paper. From the aspects of carbon reduction and indoor comfort, the ventilation system integrating a capture device is of great value in practical use. For ultra-dilute carbon dioxide sources, many traditional separation processes have no cost advantages, but adsorption technologies such as temperature vacuum swing adsorption is one of suitable methods. Thermodynamic exploration has been investigated regarding minimum separation work and second-law efficiency at various concentrations in the air. The influence of concentration, adsorption temperature, desorption temperature and desorption pressure on the energy efficiency has also been evaluated. Results show that the minimum separation work for the level of 400 ppm is approximately 20 kJ/mol. The optimal second-law efficiencies are 44.57%, 37.55% and 31.60%, respectively for 3000 ppm, 2000 ppm and 1000 ppm. It means that a high energy-efficiency capture device in buildings merits attention in the exploration of the possibility of approaching negative carbon buildings. [ABSTRACT FROM AUTHOR]

A new simple and robust solution, based on uniform steady-state flow velocity, is developed for the problem of solute transport in a fracture-matrix system with a finite penetration depth of a radioactive contaminant into the rock matrix. The solution is an extension of Liu et al. (2017) to finite penetration depth and an alternative solution strategy to the problem solved by Sudicky et al. (1982). The solution takes the form of a convolution of two functions. The first function describes the probability density function of the residence time distribution of a conservative solute resulting merely from advection and Fickian dispersion. The second function is actually the impulse response of the fracture-matrix system in the case of a plug flow without any hydrodynamic dispersion. As a result, the effects of Fickian dispersion and matrix diffusion on solute transport are decoupled, and thus the resulting breakthrough curve can be analyzed in terms of those two functions. In addition to this, the derived Péclet numbers of those two functions, based on temporal moments, are also found to be associated with the derived Péclet number of the resulting breakthrough curve. By comparing the Péclet numbers of those two functions, the contribution of Fickian dispersion and matrix diffusion to solute spreading is determined in a straightforward way. This can aid to find out the dominating mechanism on solute transport, and therefore the performance of breakthrough curve can be approximated by only one function in some specific cases. [ABSTRACT FROM AUTHOR]

A simple and robust solution is developed for the problem of solute transport along a single fracture in a porous rock. The solution is referred to as the solution to the single-flow-path model and takes the form of a convolution of two functions. The first function is the probability density function of residence-time distribution of a conservative solute in the fracture-only system as if the rock matrix is impermeable. The second function is the response of the fracture-matrix system to the input source when Fickian-type dispersion is completely neglected; thus, the effects of Fickian-type dispersion and matrix diffusion have been decoupled. It is also found that the solution can be understood in a way in line with the concept of velocity dispersion in fractured rocks. The solution is therefore extended into more general cases to also account for velocity variation between the channels. This leads to a development of the multi-channel model followed by detailed statistical descriptions of channel properties and sensitivity analysis of the model upon changes in the model key parameters. The simulation results obtained by the multi-channel model in this study fairly well agree with what is often observed in field experiments-i.e. the unchanged Peclet number with distance, which cannot be predicted by the classical advection-dispersion equation. In light of the findings from the aforementioned analysis, it is suggested that forced-gradient experiments can result in considerably different estimates of dispersivity compared to what can be found in natural-gradient systems for typical channel widths. [ABSTRACT FROM AUTHOR]

The idea of the inverse optimization problem is to adjust the value of the parameters such that the observed feasible solution becomes optimal. The modification cost can be measured by different norms, such as l 1 , l 2 , l ∞ norms and the Hamming distance, and the goal is to adjust the parameters as little as possible. In this paper, we consider the inverse minimum flow problem under the weighted sum-type Hamming distance, where the lower and upper bounds for the arcs should be changed as little as possible under the weighted sum-type Hamming distance such that a given feasible flow becomes a minimum flow. Two models are considered: the unbounded case and the general bounded case. We present their respective combinatorial algorithms that both run in O ( n m ) time in terms of the minimum cut method. Computational examples are presented to illustrate our algorithms. [ABSTRACT FROM AUTHOR]

• Three variant Time Domain Random Walk algorithms are newly developed. • The developed algorithms are applicable to an arbitrary injection boundary case. • The results from the developed algorithms are identical to the reference ones. • The accuracy of the simulation result is related to the number of particles used. In this work, three variant Time Domain Random Walk (TDRW) algorithms were developed for the problem of solute transport in a single fracture-matrix system, where an arbitrary inlet boundary condition can be applied. One approach performs an additional evaluation of integral in terms of injection boundary and the solution to a Dirac delta case. One method makes use of two functions, dependent on specific boundary conditions, to estimate the particle arrival time. The other additionally introduces the concept of solute injection time, resulting from the injection boundary, into the calculation of particle arrival time. To validate the developed variant algorithms, two benchmark cases are considered with respect to a general Dirichlet injection mode and a Robin injection boundary, respectively. The results from three approaches all make a good agreement with those of inverse Laplace transform method. However, the Monte Carlo nature of the TDRW algorithm implies that the accuracy of the computational result is highly dependent on the number of particles applied in the simulation. [ABSTRACT FROM AUTHOR]

An essential task of performance assessment of radioactive waste repositories is to predict radionuclide release into the environment. For such a quantitative assessment, the Channel Network Model and the corresponding computer program, CHAN3D, have been used to simulate radionuclide transport in crystalline bedrocks. Recent studies suggest, however, that the model may tend to underestimate the rock retarding capability, because it ignores the presence of stagnant water zones, STWZs, situated in the fracture plane. Once considered, the STWZ can provide additional surface area over which radionuclides diffuse into the rock matrix and thereby contribute to their retardation. The main objective of this paper is to extend the Channel Network Model and its computer implementation to account for diffusion into STWZs and their adjacent rock matrices. In the first part of the paper, the overall impact of STWZs in retarding radionuclide transport is investigated through a deterministic calculation of far-field releases at Forsmark, Sweden. Over the time-scale of the repository safety assessments, radionuclide breakthrough curves are calculated for increasing STWZ width. It is shown that the presence of STWZs enhances the retardation of most long-lived radionuclides except for 36 Cl and 129 I. The rest of the paper is devoted to the probabilistic calculation of radionuclide transport in fractured rocks. The model that is developed for transport through a single channel is embedded into the Channel Network Model and new computer codes are provided for the CHAN3D. The program is used to (I) simulate the tracer test experiment performed at Äspö HRL, STT-1 and (II) investigate the short- and long-term effect of diffusion into STWZs. The required data for the model are obtained from detailed hydraulic tests in boreholes intersecting the rock mass where the tracer tests were made. The simulation results fairly well predict the release of the sorbing tracer 137 Cs. It is found that over the short time-scale of the tracer experiment, the effect of diffusion into STWZs is not as pronounced as that of matrix diffusion directly from the flow channel, and the latter remains the main retarding mechanism. Predictions for longer time-scale, tens of years and more, show that the effect of STWZs becomes strong and tends to increase with transport time. It is shown that over the long times of interest for safety assessment of radioactive waste repositories, STWZs can substantially contribute to radionuclide retardation, though for the short time-scales the impact is not very strong and is not expected to affect the results of short-term field experiments. [ABSTRACT FROM AUTHOR]

Summary The paper presents a model development to derive a semi-analytical solution to describe reactive solute transport through a single channel in a fracture with cylindrical geometry. The model accounts for advection through the channel, radial diffusion into the adjacent heterogeneous rock matrix comprising different geological layers, adsorption on both the channel surface, and the geological layers of the rock matrix and radioactive decay chain. Not only an arbitrary-length decay chain, but also as many number of the rock matrix layers with different properties as observed in the field can be handled. The solution, which is analytical in the Laplace domain, is transformed back to the time domain numerically e.g. by use of de Hoog algorithm. The solution is verified against experimental data and analytical solutions of limiting cases of solute transport through porous media. More importantly, the relative importance and contribution of different processes on solute transport retardation in fractured rocks are investigated by simulating several cases of varying complexity. The simulation results are compared with those obtained from rectangular model with linear matrix diffusion. It is found that the impact of channel geometry on breakthrough curves increases markedly as the transport distance along the flow channel and away into the rock matrix increase. The effect of geometry is more pronounced for transport of a decay chain when the rock matrix consists of a porous altered layer. [ABSTRACT FROM AUTHOR]

By using a so-called differential-integral method on the chemical potential of a hard-sphere fluid, a special variant of our previously developed expression that describes the interaction between charged plates immersed in an electrolyte, is introduced to examine the hard-sphere fluid mediated pressure in a slit. The resulting expression consists of a kinetic contribution and a hard-sphere contribution, and it is formulated as a function of the single-particle direct correlation function and the density distribution of a hard-sphere fluid. It allows us to conveniently apply the classic density functional theory to explicitly investigate the influence of the hard-sphere excluded-volume effect on the interaction pressure between surfaces. In this study, a newly proposed weighted correlation approach (WCA)-Denton and Ashcroft (DA) method is employed to predict the interaction pressure as well as its pressure components for a hard-sphere fluid inside a slit pore. Comparisons with the results from the Monte Carlo simulations and the fundamental measure theory suggest that the WCA-DA method is able to accurately capture the detailed characteristic pattern of the pressure-separation curves at different fluid densities. It is also found, both qualitatively and quantitatively, that the hard-sphere pressure contribution dominates over the kinetic pressure contribution in determining the oscillatory behaviour of the interaction pressure curves, especially when a hard-sphere fluid of high density is concerned. [ABSTRACT FROM AUTHOR]

• An analytical solution is derived in a form of convolution with three functions. • A Time Domain Random Walk algorithm is developed based on the nature of functions. • The new algorithm is superior in physical reasoning and numerical implementations. • The algorithm is used to estimate concentration and its profile within matrix. In this work, a new solution is developed for the problem of contaminant transport in a single fracture-matrix system, where the first-order reaction rate constants are different in both fracture and matrix. It takes a form of convolution with three functions as a basis to consider different transport mechanisms separately. The statistical nature of the three functions, as well as the interpretation of the solution as a marginal probability distribution in the case of no first-order reactions, allows us to develop a simple Time Domain Random Walk (TDRW) algorithm to calculate the breakthrough curves at a given point of observation downstream the fracture. Compared with the existing versions of the TDRW algorithm, it is superior not only in the physical reasoning and statistical interpretations but also in its numerical implementations. In addition, the developed algorithm can not only be used to estimate the distribution profile of the contaminant concentration along the fracture but also the concentration within the matrix, since the analytical solution to contaminant concentration in the matrix also takes a convolution form of three functions. Also, the distribution profile of contaminant concentration within the matrix can readily be determined by the use of our TDRW algorithm. To validate the developed algorithm, three benchmark cases are considered for either nuclide or colloid transport through a fractured rock. The results show that TDRW algorithm is superior to the Gaussian quadrature solution, but similar to inverse Laplace transform solution, in computational expense when nearly identical results are obtained. However, the Monte Carlo nature of the TDRW algorithm implies that the accuracy of the computational result is related to the number of particles applied in the simulation, which might make the obtained results fluctuated. [ABSTRACT FROM AUTHOR]

Summary This study presents an analytical approach to simulate nuclide migration through a channel in a fracture accounting for an arbitrary-length decay chain. The nuclides are retarded as they diffuse in the porous rock matrix and stagnant zones in the fracture. The Laplace transform and similarity transform techniques are applied to solve the model. The analytical solution to the nuclide concentrations at the fracture outlet is governed by nine parameters representing different mechanisms acting on nuclide transport through a fracture, including diffusion into the rock matrices, diffusion into the stagnant water zone, chain decay and hydrodynamic dispersion. Furthermore, to assess how sensitive the results are to parameter uncertainties, the Sobol method is applied in variance-based global sensitivity analyses of the model output. The Sobol indices show how uncertainty in the model output is apportioned to the uncertainty in the model input. This method takes into account both direct effects and interaction effects between input parameters. The simulation results suggest that in the case of pulse injections, ignoring the effect of a stagnant water zone can lead to significant errors in the time of first arrival and the peak value of the nuclides. Likewise, neglecting the parent and modeling its daughter as a single stable species can result in a significant overestimation of the peak value of the daughter nuclide. It is also found that as the dispersion increases, the early arrival time and the peak time of the daughter decrease while the peak value increases. More importantly, the global sensitivity analysis reveals that for time periods greater than a few thousand years, the uncertainty of the model output is more sensitive to the values of the individual parameters than to the interaction between them. Moreover, if one tries to evaluate the true values of the input parameters at the same cost and effort, the determination of priorities should follow a certain sequence. [ABSTRACT FROM AUTHOR]

Abstract: In addition to mechanical loading, the transport properties of rock fractures are also affected by chemically mediated changes, such as pressure solution, stress corrosion and free-face dissolution, among others. Based on a time-dependent model of fracture closure under constant normal stresses, the transport behavior of contaminants in a slowly closing fracture is studied using a finite difference scheme. The results show that the contaminant penetrating along the fracture plane gradually becomes slow or almost negligible during the process of fracture closure induced by chemical processes, whereas the matrix diffusion of contaminants is active all the time. This finding indicates that diffusion into the rock matrix perpendicular to the advective flow direction always plays an important role in determining the fate of contaminant in rock fractures. The smaller the fluid flow due to fracture closure and the larger impact the matrix diffusion can further delay the solute transport. [Copyright &y& Elsevier]

Highlights: [•] A model is developed to predict swelling pressures of bentonite-based materials. [•] The model takes both crystalline swelling and osmotic swelling into account. [•] The model also accounts for disintegration of the montmorillonite particles. [•] The model predictions agree well with a great number of experimental results. [•] The model is able to predict the water retention curves of unsaturated bentonites. [Copyright &y& Elsevier]

SUMMARY The use of reversible chemical reactions in recuperation of heat has gained significant interest due to higher magnitude of reaction heat compared to that of the latent or sensible heat. To implement chemical reactions for upgrading heat, a chemical heat pump (CHP) may be used. A CHP uses a reversible chemical reaction where the forward and the reverse reactions take place at two different temperatures, thus allowing heat to be upgraded or degraded depending on the mode of operation. In this work, an exergetic efficiency model for a CHP operating in the temperature-level amplification mode has been developed. The first law and the exergetic efficiencies are compared for two working pairs, namely, CaO/CO2 and CaO/H2O for high-temperature high-lift CHPs. The exergetic efficiency increases for both working pairs with increase in task, TH, decrease in heat source, TM, and increase in condenser, TL, temperatures. It is also observed that the difference in reaction enthalpies and specific heats of the involving reactants affects the extent of increase or decrease in the exergetic efficiency of the CHP operating for temperature-level amplification. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The purpose of this study is to extend the weighted correlation approach (WCA) for inhomogeneous fluids. It now introduces a generic expression to evaluate the single-particle direct correlation function in terms of a series of pair direct correlation functions weighted by different correlation-weight functions and adjustable weight factors. When applied for practical use, however, approximations of the pair direct correlation functions have to be made, together with appropriate definitions of the weighted densities and the choices of the correlation-weight functions. The WCA approach would, then, not only help us to connect and compare different strategies and their underlying assumptions in the density functional approaches, but also enable us to propose and apply density functional theory methods to predict the density profile of, e.g., the hard-sphere fluid confined between a pair of parallel planar hard walls. Numerical results of the extended WCA approach, against the Monte Carlo (MC) simulations in a range of surface separations and bulk densities, suggest that it is capable of representing the fine features of the hard-sphere density distributions. The WCA results also agree well with the calculations from the fundamental measure theory. In addition, the thermodynamic self-consistency of the WCA approach is confirmed by its fairly good agreement with the MC fitted data for the surface tension of a hard-sphere fluid at a planar hard wall. All these tests show that a pure WCA approach can be constructed to investigate the states of ionic hard-sphere fluids. [ABSTRACT FROM AUTHOR]

Abstract: A simple yet accurate model describing the viscosity of dilute suspensions of sodium montmorillonite in dilute homoionic solutions is presented. Taking the clay particle and the surrounding clouds of ions as a whole as an uncharged but soft, coin-like particle, the Huggins’ equation for a suspension of uncharged particles is extended in the model to account for not only the primary and the secondary electroviscous effects, but also the multi-particle interaction. The agreements between the predicted and measured results are excellent. The Huggins’ coefficient obtained compares favorably with available data, while the intrinsic viscosity reduces to the Simha’s equation in the large limit of ionic strength, suggesting that the model is robust. [Copyright &y& Elsevier]

Abstract: Natural bentonite MX-80 differs from the purified and fully Na-exchanged bentonite in that it contains approximately 20.0% accessory minerals, in addition to the montmorillonite particles. Since the accessory minerals and montmorillonite particles have very different physical and chemical properties, natural bentonite MX-80 is found to expand much more slowly in distilled water, leading actually to a three-component system that has very different hydraulic properties from that of the fully Na-exchanged bentonite. To better understand and simulate the special features of expansion of natural bentonite MX-80 in distilled water, the focus is put primarily on the development of a Kozeny–Carman-like equation for its hydraulic permeability in the same way as it was done for Na-exchanged bentonite. With this permeability model, the dynamic force balance model that was originally developed for colloidal expansion of montmorillonite in a two-component system is applied to the natural MX-80 system. Without making any changes to the model, however, two strategies are used to account for both physical and chemical effects of the accessory minerals. The “lumped” strategy assumes that the accessory minerals are stuck onto the montmorillonite particles in such a way that they behave just like one solid component. The “stepwise” strategy changes the pore water chemistry gradually from initially distilled water to eventually achievement of the equilibrium condition. These strategies are simple but proved to function well. The agreement between the simulations and the experimental results indicates that the two-component dynamic force balance model works well in predicting the general features and the behavior of upward expansion of natural bentonite MX-80 in distilled water in a vertical test tube. [Copyright &y& Elsevier]

Abstract: Smectite gel formed at the outer part of a bentonite buffer in granitic rock could expand into rock fractures with seeping water. Such a gel can release colloids into low ionic strength waters. In addition the gel/sol can itself slowly flow downstream when it has reached a low particle concentration sufficient to decrease the viscosity to allow flow. The erosion due to the combined effects of particle diffusion and gel/sol flow is modelled for a thin fracture into which the gel expands influenced by various forces between and on particles. Some of the forces such as the electrical double layer force and viscous force are strongly influenced by the ionic strength of the pore water. Changes in the ionic strength due to diffusion and dilution of ions in the expanding clay are modelled simultaneously with the gel expansion, flow of gel and colloid release to the seeping water. The model includes description of flow of the seeping fluid, which gradually turns from pure water to sol to more dense gel as the smectite source is approached. The model also describes expansion of the gel/sol and colloid release and flow and diffusion of ions in the system. The coupled models are solved using a numerical code. The results show that the gel will flow with a non-negligible flowrate when its volume fraction is below 1%, but that the erosion and loss of smectite is not much influenced by the concentration of sodium in the clay or in the approaching seeping water, if they are kept below the Critical Coagulation Concentration, CCC. [Copyright &y& Elsevier]

Abstract: In developing the dynamic force balance model for colloidal expansion, it was acknowledged that accurate description of the viscous drag force, or equivalently the permeability, is very important to describe the swelling process of compacted bentonite as it expands and eventually turns from a gel into a sol in low ionic strength waters. We therefore developed a Kozeny–Carman-like equation to quantify the permeability of the purified and fully Na-exchanged bentonite in dilute homoionic solutions, based on a set of permeability measurements. The force balance model, together with a friction model derived from the permeability, is then validated against accurate observations of the expansion process of the Na-exchanged bentonite in a water filled vertical test tube. The expansion is followed in detail over a month, by use of the magnetic resonance imaging technique with a spatial resolution of 0.2mm, as an initially compacted tablet of Na-bentonite expands in water. The model accurately predicts not only the expansion rate and the general features of the expansion but also the basic behaviour at the expanding gel/sol interface. In addition, the use of the developed Kozeny–Carman-like equation substantiates that the expansion rate depends strongly on the friction of the particles against the water. [Copyright &y& Elsevier]

Capacitive energy extraction based on double layer expansion (CDLE) is a renewable method of harvesting energy from the salinity difference between seawater and freshwater. It is based on the change in properties of the electric double layer (EDL) formed at the electrode surface when the concentration of the solution is changed. Many theoretical models have been developed to describe the structural and thermodynamic properties of the EDL at equilibrium, e.g., the Gouy–Chapman–Stern (GCS), Modified Poisson–Boltzmann–Stern (MPBS), modified Donnan (mD) and improved modified Donnan (i-mD) models. To evaluate the applicability of these models, especially the rationality and the physical interpretation of the parameters that were used in these models, a series of single-pass and full-cycle experiments were performed. The experimental results were compared with the numerical simulations of different EDL models. The analysis suggested that, with optimized parameters, all the EDL models we examined can well explain the equilibrium charge–voltage relation of the single-pass experiment. The GCS and MPBS models involve, however, the use of physically unreasonable parameter values. By comparison, the i-mD model is the most recommended one because of its accuracy in the results and the meaning of the parameters. Nonetheless, the i-mD model alone failed to simulate the energy production of the full-cycle CDLE experiments. Future research regarding the i-mD model is required to understand the process of the CDLE technique better. [ABSTRACT FROM AUTHOR]

Abstract: The inverse optimization problem is to modify the weight (or cost, length, capacity and so on) such that a given feasible solution becomes an optimal solution. In this paper, we consider the inverse min–max spanning tree problem under the weighted sum-type Hamming distance. For the model considered, we present its combinatorial algorithm that runs in strongly polynomial times. [Copyright &y& Elsevier]

Abstract: Various approximate solutions to the Poisson-Boltzmann (PB) equation have been derived to describe the interaction of electric diffuse double layers adjacent to charged surfaces. However, all these expressions are case-specific and accurate only in limited ranges of particle separations. None can cover the entire range of plate separations and/or surface charge densities generally found in real systems. In this paper, we derive an approximate expression for the force between two parallel similar plates with constant surface charge densities in a symmetrical electrolyte solution, which agrees well with the rather complex exact analytical solution over a wide range of plate separations. The method used is based on the so-called “compression” approach developed previously for the case of low surface charge densities. The results are also in good agreement with “exact” numerical solutions over a wide range where no restriction is actually required on the magnitudes of the surface charge densities, surface potentials or the distance between the plates. Furthermore, an expression for the derivative of the force is also given, which is fairly simple and is very useful in modelling, e.g. colloidal transport problems based on a force balance on particles in a colloidal system. In such cases it is very impractical to use either the exact analytical or numerical solution to the PB equation. [Copyright &y& Elsevier]

In this paper, we consider two network improvement problems with given discrete values: the inverse minimum spanning tree problem and the reverse shortest-path problem, where the decrements of the weight of the edges are given discrete values. First, for the three models of the inverse minimum spanning tree problem (the sum-type, the bottleneck-type and the constrained bottleneck-type), we present their respective strongly polynomial algorithms. Then, we show that the reverse shortest-path problem is strongly NP-complete. [ABSTRACT FROM AUTHOR]

• A simple and robust transient solution is developed and takes a convolution form. • The solution is applicable to a single channel system with cylindrical geometry. • The solution aids to develop a simple Time Domain Random Walk (TDRW) algorithm. • The simple algorithm is extended to improve calculation efficiency and accuracy. • The extended TDRW algorithm becomes applicable to more complicated cases. Numerous field observations show that the channels in one fracture are narrow and the solute penetration depth might be larger than the width. For this case, the diffusion from a channel into the matrix is more realistic to be modeled as radial diffusion than one-dimensional. In present work, the single channel model with radial diffusion is revisited and a simple and robust analytical solution is developed. This solution takes a convolution form of two functions, in which different transport mechanisms are accounted for. The statistical interpretations of the two functions and the analytical solution aid to develop a simple Time Domain Random Walk (TDRW) algorithm and an extension is made to improve its accuracy, efficiency and applicability. To demonstrate the accuracy and efficacy of the extended algorithm, three groups of simulations are performed and it is found that the results of all approaches are identical. The TDRW algorithm, having the same performance as that of inverse Laplace transform solution, is superior to Gaussian quadrature method in computational time. However, due to Monte Carlo nature of the algorithm, the computational burden of TDRW algorithm is dependent on the number of particles applied, which also influences the calculation accuracy. Therefore, a trade-off between computational burden and calculation accuracy should always be made, once the TDRW algorithm is used. [ABSTRACT FROM AUTHOR]

An open circuit voltage-based model for state-of-health estimation of lithium-ion batteries is proposed and validated in this work. It describes the open circuit voltage as a function of the state-of-charge by a polynomial of high degree, with a lumped thermal model to account for the effect of temperature. When applied for practical use, the model requires a prior learning from the initial charging or discharging data for the sake of parameter identification, using e.g. a nonlinear least squares method, but it is undemanding to implement. The study shows that the model is able to estimate the state-of-health of a LiFePO 4 cell cycled under conditions where the temperature has fluctuated significantly with a relative error less than 0.45% at most. A short part of a constant current profile is enough for state-of-health estimation, and the effect of size and location of voltage window on the model's accuracy is also studied. In particular, the reason of accuracy change with different voltage windows is explained by incremental capacity analysis. Additionally, the versatility and flexibility of the model to different chemistries and cell designs are demonstrated. • An open circuit voltage-based model is proposed to estimate the SOH of LIBs. • The accuracy of the model is validated by experimental results of an LFP cell. • The effect of size and location of voltage window on the model accuracy is studied. • ICA is used to explain the model accuracy change with different voltage window. • The versatility of the model to different chemistries is demonstrated. [ABSTRACT FROM AUTHOR]

Carbon dioxide capture from the post-combustion flue gas via temperature swing adsorption is supposed to be a valid technology to mitigate carbon emissions. With regard to the adsorbent development and process improvement, the technologies of temperature swing adsorption for post-combustion carbon dioxide capture have been reviewed and compared in terms of fixed bed, fluidized bed and moving bed. A comprehensive evaluation framework of fixed-bed temperature swing adsorption for CO 2 capture has been established. In a four-step fixed-bed cycle, a shortcut model has been utilized. Four typical adsorbent materials, such as activated carbon, zeolite 13X, zeolite NaUSY and Mg-MOF-74, have been chosen in this assessment. The comparative study has been conducted under the same operating conditions, from four aspects using eight performance indicators. Results indicate that Mg-MOF-74 and zeolite 13X reveal excellent performance among the four selected adsorbents. Thereinto, Mg-MOF-74 performs well at four indicators including purity, productivity, specific thermal energy consumption and second-law efficiency; zeolite 13X excels in the other four indicators such as selectivity, recovery, minimum separation work and capture cost. Future work will complete a thorough assessment criterion in evaluating the TSA process for CO 2 capture. Image 1 • Research on adsorption based TSA process for PCC has been summarized and reviewed. • 4 adsorbents have been compared in a 4-step fixed-bed TSA cycle by 8 indicators. • Mg-MOF-74 and zeolite 13X show excellent performance among the selected adsorbents. • Mg-MOF-74 excels in purity, productivity, energy consumption and 2nd law efficiency. • Zeolite 13X performs well at selectivity, recovery, minimum work and capture cost. [ABSTRACT FROM AUTHOR]

The migration behavior of Se(IV) and Re(VII) in muscovite was studied by capillary diffusion method and diffusion cell method. The results show that diffusion accelerates when the density decreases and the ionic strength increases. At the same time, pH also significantly affects their migration. The apparent diffusion coefficient ranges from 10–11 to 10–9 m/s2. This work can provide potential applications in deep geological nuclear waste repositories. [ABSTRACT FROM AUTHOR]

A simple approach for preparing high-efficiency and cost-effective adsorbent to extract uranium in nuclear wastewater is essential for safeguarding the environment. This study introduces an easy procedure to synthesize phosphate-rich biochar (PS) from sawdust by treating it with phosphoric acid before carbonization (700 °C). The sample was characterized by SEM, FT-IR, BET and XPS, indicating that the PS700 exhibited a high concentration of phosphorous groups, high specific surface area and developed mesoporous structure. Subsequently, the effects of pH (optimal at pH 7), adsorption kinetics (fitted by quasi-second-order), and sorption isotherms (modeled by Langmuir) were investigated. The best uranium (VI) adsorption performance of PS700 is 808 mg g−1 at 40 °C and pH 7. In addition, PS700 shows remarkable selectivity and recyclability for uranium (VI). The sorption mechanism can be attributed to the uranium (VI) binding with phosphate groups on the surface of sorbent, which significantly improve its ability for uranium (VI) adsorption. This study displays a great application prospect of PS700 as innovative adsorbent for the efficient extraction of uranium (VI) from nuclear wastewater. [ABSTRACT FROM AUTHOR]

In an inverse combinatorial optimization problem, a feasible solution is given and is not optimal under the current parameters. The aim is to make the feasible solution optimal by modifying the current parameters as little as possible. The modification cost can be measured by different norms, such as weighted l 1 norm, weighted l 2 norm, weighted l ∞ norm, weighted Hamming distance and so on. In this paper, we focus on the constrained inverse minimum flow problems under the weighted Hamming distance. Three different models are considered: the general problem under the weighted bottleneck-type Hamming distance and two cases under the mixed of sum-type and bottleneck type. Strongly polynomial algorithms are presented for the models we studied. [ABSTRACT FROM AUTHOR]

Computer vision obtains object and environment information by simulating human visual senses and borrowing human sensory activity. As one of the main tasks of computer vision, image classification can be used not only for face recognition, traffic scene recognition, image retrieval, and automatic photo categorization but also as a theoretical basis for target detection and image segmentation. In this paper, we use the existing CNN architecture network-ConvNeXt. By adapting and modifying the residual connectivity and convolutional structure of the network, we achieve a balance between classification accuracy and inference speed. These modifications are able to reduce both computation and memory consumption while keeping accuracy largely unchanged, thus better facilitating network lightweighting. [ABSTRACT FROM AUTHOR]

Semantic segmentation in indoor environments is a crucial task for artificial intelligence-driven visual robotics, enabling pixel-level classification results to facilitate robot path planning. Inspired by the success of multimodal models, we propose an end-to-end multimodal semantic segmentation model for image segmentation tasks in indoor scenes, which we call OIPNet. We design the OIP module to enhance the network's ability to extract global information and enable information interaction in different directions. We have validated on NYUv2 and Sun RGB-D datasets, and the experiments show the generality and effectiveness of the proposed model. Our code is available at https://github.com/Mantee0810/OIP. [ABSTRACT FROM AUTHOR]

Long-term self-irradiation of high-level waste (HLW) matrices may cause diverse microstructural changes, which can degrade their immobilization performance. This study reports the irradiation-induced redox response of Ce-doped pyrochlores, which can be attributed to the damage process in pyrochlores. Lu 2 Ti 2 O 7 and Lu 1.46 Ce 0.54 Ti 2 O 7+ x pyrochlores were irradiated by 400 keV Ne2+. The coordinate environment of the elements was characterized by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and Raman spectroscopy, while the chemical compositions of the samples were analyzed by scanning electron microscopy. First, the irradiation-induced oxidation of Ce was observed in Lu 1.46 Ce 0.54 Ti 2 O 7+ x at doses of 0–0.052 dpa, and the Ce3+ content was found to decrease from 61.73% to 58.44%. When the dose was increased to 0.261 dpa, the valency of Ce was reduced, and the Ce3+ content increased to 59.25%. Herein, the reduction behavior is discussed in terms of amorphization and recrystallization in the irradiated Lu 1.46 Ce 0.54 Ti 2 O 7+ x. This irradiation-induced redox behavior of Ce-doped pyrochlores provides another perspective for predicting the long-term performance of HLW matrices in repositories. [ABSTRACT FROM AUTHOR]

Biotite is an important adsorption carrier in the constituent minerals of Beishan granite. In this work, the effects of compaction density and ionic strength on the diffusion behavior of Se(IV) and Re(VII) in biotite were studied by capillary in-diffusion method and diffusion cell through-diffusion method. When the compaction density decreases or the ionic strength increases, the apparent diffusion coefficient increases, and its values range between 10–11 and 10–9 m2/s. The relationship between De and εacc, ionic strength and εacc was fitted using Archie's law and compared with the parameters of other researchers. [ABSTRACT FROM AUTHOR]

Although the expression of miRNAs has been widely applied to investigate on gonads, the role of miRNAs in the gonadal development of white Pacific shrimp (Litopenaeus vannamei) remains unknown. In this study, we performed high-throughput sequencing to identify the sex-related microRNAs (miRNAs) that elucidated the regulatory mechanisms on the gonadal differentiation of L. vannamei. We obtained a total of 29,671,557 and 28,526,942 raw reads from the ovaries and testes library, respectively. We then mapped 26,365,828 (92.73%) of the ovarian clean sequences and 23,694,294 (85.65%) of the testicular clean sequences for a transcriptome reference sequence of L. vannamei. After blasting the miRNA sequences against the miRBase database, we identified 153 significantly differentially expressed miRNAs between the ovaries and testes. To confirm the high-throughput sequencing results, we used a reverse transcriptase–quantitative polymerase chain reaction (RT-qPCR) to verify the expression patterns of the seven most differentially expressed miRNAs (i.e., novel_mir23, miR-92b-3p_3, miR-12-5p_2, novel_mir67, miR-279_1, let-7-5p_6, miR-263a-5p_1). According to the results of RT-qPCR, most of the miRNAs were expressed consistently with the high-throughput sequencing results. In addition, the target genes significantly enriched several Kyoto Encyclopedia of Genes and Genome (KEGG) pathways that were closely related to gonadal differentiation and development, including extracellular matrix–receptor interaction, Hedgehog signaling pathway, protein digestion and absorption and cell adhesion molecules (CAMs). This study revealed the first miRNAs sequencing of L. vannamei gonads. We identified sex-related differentially expressed miRNAs and KEGG pathways, which will be helpful to facilitate future research into the regulatory mechanism on the gonadal differentiation of L. vannamei. [ABSTRACT FROM AUTHOR]

In this study, a novel adsorbents, molybdenum disulfide-graphene oxide (MoS2–GO) composites, is prepared by one-step hydrothermal method and used for U (VI) adsorption. SEM, XRD, FT-IR, BET and XPS results show that the MoS2 layers grow on the surface of graphene oxide layers, forming MoS2–GO composite structure. The specific surfaces area of MoS2–GO composite (5.5 m2/g) is higher than that of MoS2 (2.3 m2/g). Batch adsorption experiments indicate that the adsorption process of uranium (VI) on MoS2–GO conforms to the quasi-second-order kinetic model and the adsorption isotherm accords with Langmuir model. The maximum adsorption capacity calculated by Langmuir model is 136 mg·g−1 at pH 5.0 and 298 K. Meanwhile, MoS2–rGO displays excellent selectivity for U (VI) in multicomponent metal ion solution. The increasement in specific surface area and the introduction of GO that rich in O-containing groups, provide more accessible binding sites for U (VI), which greatly enhance its uranium uptake capability. This work shows the potential of MoS2–GO as novel and promising materials in the efficient elimination of U (VI) from contaminated water and industrial effluents. [ABSTRACT FROM AUTHOR]

The state of health (SOH) is a vital parameter enabling the reliability and life diagnostic of lithium-ion batteries. A novel fusion-based SOH estimator is proposed in this study, which combines an open circuit voltage (OCV) model and the incremental capacity analysis. Specifically, a novel OCV model is developed to extract the OCV curve and the associated features-of-interest (FOIs) from the measured terminal voltage during constant-current charge. With the determined OCV model, the disturbance-free incremental capacity (IC) curves can be derived, which enables the extraction of a set of IC morphological FOIs. The extracted model FOI and IC morphological FOIs are further fused for SOH estimation through an artificial neural network. Long-term degradation data obtained from different battery chemistries are used for validation. Results suggest that the proposed fusion-based method manifests itself with high estimation accuracy and high robustness. [ABSTRACT FROM AUTHOR]

• Facile and scalable synthesis of phosphorus-doped biochar from pomelo peel. • High uranium removal efficiency and good selectivity. • Dynamic adsorption of uranium from real nuclear wastewater. • Investigation of the mechanism based on DFT calculations. The phosphoric acid activated biochar adsorbent is recognized as a good candidate for application in efficient disposal of uranium-containing nuclear wastewaters. However, the production of high-efficiency biochars with typical characteristics of large specific surface area, hierarchically porous structure and abundant adsorption group remains a challenge. In this work, we report a new hydrogelation-carbonization technique to facilely produce phosphorus-doped biochar from pomelo peel and meantime provide new sights into the interaction mechanism of phosphoric acid groups with uranium ion. An interesting hydrogelation phenomenon is found when simply mixing the phosphoric acid solution and pomelo peel powder. The resulted hydrogel readily undergo carbonization to produce desired biochar. The biochar exhibits good uranium removal efficiency (up to 99 %) with a maximum adsorption capacity of 603 mg/g at 313 K. The distribution coefficient of uranium (VI) attains 10.8 L/g. The biochar undergoes five desorption-adsorption cycles with desorption and adsorption efficiencies above 95 %. It can be applied in fix-bed column for dynamic adsorption of uranium from uranium-containing solutions and real nuclear wastewater with an adsorption capacity over 422 mg/g. Rather than direct interaction with uranium ion, our experimental and computational results reveal that the surface phosphoric acid groups initially undergo in-situ ionization to produce phosphonates and the complexation of phosphonate with uranium ion results in effective uranium adsorption. This work demonstrates the high efficiency of pomelo peel biochar for disposal of uranium-containing nuclear wastewater, and offers new insights into the mechanism of uranium adsorption on the adsorbents containing phosphoric acid and phosphonate groups. [ABSTRACT FROM AUTHOR]

The perceptual scope of deep convolutional neural networks is inherently confined to a local scale due to the inherent limitations of convolution operations. This confinement subsequently hampers a comprehensive understanding of intricate scenes. In response, an innovative approach called Bilateral Non-Local Decoupled Convergence Network (BNDCNet) is proposed to facilitate contextual interaction of global information. The proposed module decouples the information from the input feature map and uses a bilateral non-local architecture for system processing. This strategy facilitates inter-pixel interaction and aggregates global information. An important aspect of our approach involves the computation of adaptive convolutional channel weights for the feature map. This innovation greatly improves the efficacy and performance of the model. The proposed method achieved high performance on the competitive scene-parsing datasets CamVid, Cityscapes, and KITTI, and thus demonstrated effectiveness and generality. Code has been released: https://github.com/Mantee0810/BNDC. • The addition of this module improves segmentation performance. • Decoupling the channel message of the feature map for information interaction. • Extracting information and reconstructing feature maps by tensor operations. [ABSTRACT FROM AUTHOR]

The accurate estimation of the state-of-health (SOH) is vital to the life management of lithium-ion batteries (LIBs). In this article, we propose a fusion-type SOH estimation method by combining the model-based feature extraction and data-based state estimate. Particularly, a novel model-based voltage construction method is proposed to eliminate the unfavorable numerical condition and reshape the disturbance-free incremental capacity (IC) curves. Leveraging the modified IC curves, a set of informative features-of-interest is extracted and evaluated, while eventually several cautiously selected ones are used to estimate the SOH of LIBs accurately. Furthermore, the impact of model order on the estimation performance is scrutinized to give insights into the parameterization in practical applications. Long-term cycling tests on different types of LIB cells are used for evaluation. The proposed method is validated with a good robustness to the cell inconsistency, temperature uncertainty, noise corruption, and a satisfied generality to different battery chemistries. [ABSTRACT FROM AUTHOR]

A surface complexation model of Se(IV) sorption on biotite with one type of strong sorption sites and two types of weak sorption sites were developed based on experimental data obtained from titration, sorption edge and sorption isotherm experiments. Titration data was collected using a batch-wise manner together with backtitration to calibrate the effect of mineral dissolution in 0.01 M KClO 4 background electrolytes from pH 3 to 11 in an inert atmosphere glovebox. Further calibrations of the titration curve include proton exchange and cation exchange in which the calculations of cation occupancies on biotite surfaces were taken into account. The sorption edge measurements were determined by measuring the sorption of 10−9 M total Se with a radioactive Se-75 tracer on converted biotite in 0.01 M KClO 4 solution from pH 3 to 11. Se sorption was observed to be strongly dependent on pH. Surface complexation modelling was performed by deriving a set of optimized parameters that can fit titration, sorption edge and sorption isotherm (at pH ~7.7) experimental data. A CASTEP code implemented into Materials Studio was used to calculate the site densities and site types on the biotite surfaces. Weak sorption sites with site densities of 3.2 sites/nm2 and 1.4 sites/nm2 were derived from the codes and used in the sorption model. A computer code that coupled PHREEQC with Python was developed for the fitting and optimizing processes. The model was validated by sorption data at pH ~9.5. The results show that the model can provide quantitative predicts of Se(IV) sorption in groundwater conditions of a deep geological repository and help improve the performance assessments by giving more convincing estimates of the release of radionuclides towards aquifers and biosphere. • A surface complexation model of Se(IV) sorption on biotite was developed. • Titration data were calibrated for the effect of mineral dissolution. • Sorption edge data were modelled and sorbed species were illustrated vs pH. • Molecular modelling was used to calculate the site densities and site types. • Coupling of PHREEQC with Python was developed for fitting and optimizing. [ABSTRACT FROM AUTHOR]

Organophosphorus acid polymers with high hydrophilicity and limited swelling capacity have great application potential in disposal of uranium (VI)-containing wastewater due to its high uranium (VI) adsorption efficiency. In this work, POSS-crosslinked poly(vinylphosphonic acid) polymer is synthesized via copolymerization of octavinyloctasilasesquioxane and vinylphosphonic acid for uranium (VI) adsorptive removal from solution. The polymer has a high hydrophilicity and limited swelling capacity. The uranium (VI) adsorptive removal is performed in batch mode and the effects of polymer dosage, pH and ionic strength are investigated. The polymer shows high removal efficiency for uranium (VI) from a 120 mg L−1 solution and can achieve the complete uranium (VI) removal at 30 °C and pH 4.0 with 0.33 g L−1 polymer. The adsorption process is analyzed by comparison with the adsorption kinetic and isotherm models. Uranium (VI) adsorption on this polymer is found to be more consistent with the pseudo-second-order and Langmuir models, and the maximum adsorption capacity attains 714 mg g−1. Competitive adsorption between uranium (VI) and other metal ions on polymer is performed to analyse the adsorption selectivity. The polymer attains a 20 L g−1 uranium (VI) distribution coefficient, higher than other metal ions (0.1–1.8 L g−1). The polymer can be easily recycled for at least five times with removal efficiency above 99% and the polymer can be well applied for dynamic adsorptive removal of uranium (VI) from uranium-containing solution (5 mg L−1) in a fixed-bed column with removal efficiency above 99%. The excellent uranium (VI) removal performances of this composite polymer highlight its great potential in the disposal of uranium-containing nuclear wastewater. [Display omitted] • Segregative organophosphorus acid polymer is used for uranium (VI) removal. • The polymer have high hydrophilicity and limited swelling capacity. • The polymer shows high removal efficiency and selectivity for uranium (VI). • The polymer is well applied in the fixed-bed column. [ABSTRACT FROM AUTHOR]

The advection-dispersion equation, ADE, has commonly been used to describe solute transport in fractured rock. However, there is one key question that must be addressed before the mathematical form of the so-called Fickian dispersion that underlies the ADE takes on physical meaning in fractures. What is the required travel distance, or travel time, before the Fickian condition is met and the ADE becomes physically reasonable? A simple theory is presented to address this question in tapered channels. It is shown that spreading of solute under forced-gradient flow conditions is mostly dominated by advective mechanisms. Nevertheless, the ADE might be valid under natural flow conditions. Furthermore, several concerns are raised in this paper with regard to using the concept of a field-scale matrix diffusion coefficient in fractured rocks. The concerns are mainly directed toward uncertainties and potential bias involved in finding the continuum model parameters. It is illustrated that good curve fitting does not ensure the physical reasonability of the model parameters. It is suggested that it is feasible and adequate to describe flow and transport in fractured rocks as taking place in three-dimensional networks of channels, as embodied in the channel network concept. It is argued that this conceptualization provides a convenient framework to capture the impacts of spatial heterogeneities in fractured rocks and can accommodate the physical mechanisms underlying the behavior of solute transport in fractures. All these issues are discussed in relation to analyzing and predicting actual tracer tests in fractured crystalline rocks. [ABSTRACT FROM AUTHOR]

The formation of high concentrations of acid gases; in combustion with large variations in fuel qualities, represents a major challenge for energy production from contaminated biomass fuels. This paper provides a comprehensive evaluation of the effects of acid gas formation and retention in the combustion of recycled wood fuels. A model has been developed based on the chemical reactions involved and empirical correlations from plant monitoring and testing. The model has been used to study the behaviour of acidic gas components in critical stages of a bubbling fluidised bed boiler process. Results indicate that the variation in type of fuel contamination is the most important issue to deal with in the combustion of recycled wood fuels. Peaks in the flue gas chlorine concentrations cannot be suppressed easily by conventional flue gas cleaning measures. Upon applying ammonium sulphate dosing for the protection of chlorine induced corrosions, it is sometimes difficult to maintain the required S/Cl ratio when large variations of fuel chlorine occur. Moreover, a high level of chlorine in the fuel can also indirectly affect the emission control of sulphur dioxide because it would require an increased level of ammonium sulphate decomposition, which results in a high level of SO 2 in flue gas. The study also shows a beneficial effect of the recirculation of quench water from the flue gas condenser to the boiler. It offers opportunities for the optimisation of flue gas cleaning and flue gas condensation, for improving the efficiencies of water and wastewater treatment, as well as for emission reduction with a sustainable way. [ABSTRACT FROM AUTHOR]

Uranium has been recognized as one of the most desired radionuclides that has long been used in reactor. The efficient extraction of uranyl (VI) ions from radioactive effluents and seawater is an ideal way to collect uranium, however it is always a challenge to develop high-efficiency adsorbents for effective uranium uptake. In this paper, a series of phosphate-containing mesoporous carbon (PC) are fabricated by the carbonization of sucrose and phytic acid upon using nanosized silica as hard template. The obtained PC have high-content phosphate group, large specific surface area and tunable mesoporous structure. The PC can efficiently adsorb uranium at a wide pH conditions. The maximum uptake capacity of PC for uranium reaches 928 mg g −1, ranking as one of the most highly effective adsorbents. The mesopores of PC enables them to quickly reach the adsorption equilibrium within 60 s and meantime PC show excellent adsorption selectivity. Investigations of adsorption mechanism reveals that uranyl (VI) ions tend to bind with the surface P-OH groups to form P-O-U complexes, leading to the effective uranium extraction. Moreover, PC displays good recyclability and can be further used for dynamic column adsorption of uranyl (VI) ion from uranium-containing solution. The excellent adsorption performances of PC highlight their great potential in uranium extraction. [Display omitted] • Phosphate-containing mesoporous carbons were prepared for effective uranium extraction. • The adsorbents have high-content phosphate group, large specific surface area and tunable mesoporous structure. • The adsorbents displayed both high adsorption capacity, adsorption rate and selectivity for uranium. • Phosphate group can effectively bind with uranyl (VI) ion to form uranyl phosphate complexes [ABSTRACT FROM AUTHOR]