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The adaptive versions of charting tools are well-established statistical monitoring techniques for detecting unknown changes in the process over a range of shifts. A re-weighted adaptive CUSUM mean (RACUSUM) charting scheme has been proposed in this study for monitoring the range of shifts. The proposed RACUSUM statistic estimates the unknown changes in the ongoing process using an EWMA statistic by plugging in an unbiased shift estimator and choosing a suitable smoothing constant according to the estimated shift to update the slack value of the CUSUM statistic. By employing Monte Carlo simulation using the zero- and steady-state processes, the proposal's run-length (RL) profiles have been calculated. The proposed RACUSUM chart shows more sensitive behavior under the shift delay process than in the case of zero-state. A comparative analysis between the proposal and competitors has been presented using average RL, extra quadratic loss (EQL), and the relative mean index (RMI) as metrics for 1-sided and 2-sided charting schemes. The robustness of the proposed 2-sided RACUSUM chart against non-normality has also been reported. The proposal's applicability has been demonstrated using two cases, one from the artificial and the other from a dataset of piston ring manufacturing industrial process. [Display omitted] • A new re-weighted adaptive CUSUM (RACUSUM) mean chart is designed to monitor shifts in the interval. • The proposal RACUSUM statistic estimates the unknown shift in the process mean. • The run-length (RL) profiles of the 1-sided and 2-sided proposed RACUSUM charts are evaluated using Monte Carlo simulation. • The extra quadratic loss (EQL) and relative mean index (RMI) metrics have been selected for the shifts in the interval. • The designed structure is applied to real piston ring industrial process data. [ABSTRACT FROM AUTHOR]

• The effect of the crankshaft starting position on startup vibration is investigated. • Startup vibrations are analytically modeled and validated with experimental results. • Optimal starting crank angle ranges are revealed for a smoother startup. • The bottom-dead center position is found to be the most undesirable start position. The maximum reciprocating compressor vibrations occur during the startup and shutdown operations and understanding the factors that influence the transient vibrations can help in developing solutions to reduce the excessive displacements. In this study, the effect of crankshaft starting position on the vibration phenomenon is investigated and the optimal starting position to deliver a smooth start is proposed. The structural forces are analytically modeled to estimate the body displacements by considering the system resonance frequencies and modal vectors. An experimental setup is also constructed to validate the prediction model results, with the integration of an encoder to track the crankshaft angular position and transducers to measure the discharge and suction pressures. The transient responses of three different crankshaft start positions are then compared using the experimental setup and the analytical model. The results indicate that if the crankshaft starts to rotate from positions close to the bottom dead center, a higher amount of startup vibrations is observed, revealing the optimal starting position zone. The magnetization effect can potentially be addressed by the sensorless starting strategy developed by Lee et al. (2008) that implements a phase current controller for a smoother startup. While out of scope for this study, shutdown strategies can also be devised to have the piston consistently land at the favorable SAP range. By separately investigating the instances when the 'stop' command is provided to the steady-state operating compressor, solutions that attempt to replicate the conditions that lead to the favorable stop position can be developed; a limiting factor in mass production will be implementing the encoder for continuous position tracking and an accompanying undesirable cost increase in manufacturing. Nevertheless, the investigation of passive and active strategies is ripe for research in literature. [ABSTRACT FROM AUTHOR]

We study a two-stage structured population model for which the juveniles diffuse purely by random walk while the adults exhibit long range dispersal. Questions on the persistence or extinction of the species are examined. It is shown that the population eventually dies out if the principal spectrum point λ p of the linearized system at the trivial solution is nonpositive. However, the species persists if λ p > 0. Moreover, at least one positive steady state exists when λ p > 0. The uniqueness and global stability of the positive steady-state solution is obtained under some special cases. We also establish a sup/inf characterization of λ p. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of the existence and stability of non-trivial steady state solutions to the following coupled system of PDEs on the half-line R + = (0 , ∞) : u t = u x x − χ [ u (ln w) x ] x , w t = ɛ w x x − u γ w m , which is a model of chemotaxis of Keller–Segel type. When u is subject to the no-flux boundary condition, w equals a positive value at the origin, and assuming the functions vanish at the far field, a unique steady state (U , W) is constructed under suitable restrictions on the system parameters, which is capable of describing fundamental phenomena in chemotaxis, such as spatial aggregation. Moreover, the steady state is shown to be nonlinearly asymptotically stable if (u 0 − U) carries zero mass, w 0 (x) matches W (x) at the far field, and the initial perturbation is sufficiently small in weighted Sobolev spaces. [ABSTRACT FROM AUTHOR]

Makena (17-hydroxyprogesterone caproate) was approved by the United States Food and Drug Administration for the prevention of recurrent spontaneous preterm birth in 2011 under the accelerated approval pathway, but fundamental pharmacokinetic or pharmacodynamic (Phase 1 and Phase 2) studies were not performed. At the time, there were no dose-response or concentration-response data. The therapeutic concentration was not known. The lack of such data brings into question the dosing regimen for 17-hydroxyprogesterone caproate and if it was optimized. The purpose of this study was to evaluate the dosing regimen for 17-hydroxyprogesterone by analyzing 3 data sets in which the 17-hydroxyprogesterone caproate pharmacology was evaluated, namely the Maternal-Fetal Medicine Omega 3 study, the Obstetric-Fetal Pharmacology Research Units study, and the Obstetrical-Fetal Pharmacology Research Centers study. If an inappropriate dosing regimen could be identified, such information could inform future studies of pharmacotherapy in pregnancy. Data from the Omega 3 study were used to determine if plasma concentration was related to spontaneous preterm birth risk and if a threshold concentration could be identified. Data from the Obstetric-Fetal Pharmacology Research Units study were used to determine the half-life of 17-hydroxyprogesterone caproate and to develop a model to simulate drug concentrations with various dosing regimens. Data from the Obstetrical-Fetal Pharmacology Research Centers study were used to determine the relationship between dose and safety outcomes. Analysis of the Omega 3 data set indicated that the risk for spontaneous preterm birth decreased as the log concentration of 17-hydroxyprogesterone caproate increased (odds ratio, 0.04; 95% confidence interval, 0.00–0.90). A steady state concentration of >9 ng/mL (equivalent to >8 ng/mL at 25–28 weeks) was associated with the lowest risk for spontaneous preterm birth (hazard ratio, 0.52; 95% confidence interval, 0.27–0.98; P =.04); this concentration was not achieved in 25% of subjects who received the 250 mg weekly dose. In the Obstetrical-Fetal Pharmacology Research Units study, the adjusted half-life (median and interquartile range) of 17-hydroxyprogesterone caproate was 14.0 (11.5–17.2) days. Simulations indicated that with the 250 mg weekly dose, >5 weekly injections were required to reach the 9 ng/mL target; however, those with the shortest half-life (corresponding to higher clearance), never reached the targeted 9 ng/mL concentration. In 75% of subjects, a loading dose of 500 mg weekly for 2 weeks followed by 250 mg weekly achieved and maintained the 9 ng/mL concentration within 2 weeks but in those 25% with the shortest half-life, concentrations exceeded the 9 ng/mL target for only 3 weeks. In the Obstetrical-Fetal Pharmacology Research Centers study, all 65 subjects who received a weekly dose of 500 mg exceeded the 9 ng/mL steady state. The dosing regimen for 17-hydroxyprogesterone caproate was inadequate. There is a significant inverse relationship between drug concentration and spontaneous preterm birth. The risk was lowest when the concentration exceeded 9 ng/mL, but 25% of women who received the 250 mg weekly dose never reached or maintained this concentration. The drug's long half-life necessitates a loading dose to achieve therapeutic concentrations rapidly. The omission of basic pharmacologic studies to determine the proper dosing may have compromised the effectiveness of 17-hydroxyprogesterone caproate. Future pharmacotherapy trials in pregnancy must first complete fundamental pharmacology studies. [Display omitted] [ABSTRACT FROM AUTHOR]

• Vehicle swap strategy to mitigate the wild goose chase phenomenon in taxi systems. • Analytical model to predict system performance in the steady-state. • New data-processing method based on dynamic programming to measure multiple distinct equilibria from data. • Analytical predictions are well corroborated by measurements from agent-based simulations. This paper examines the so-called wild goose chase phenomenon in taxi systems and proposes a new mitigation strategy based on dynamic vehicle swaps. An analytic queuing network model, including a system of differential equations, is derived to yield approximate formulas for the expected system performance in the steady-state equilibria under the vehicle swap strategy. This model is solved numerically to yield equilibrium points and the expected system performance metrics. To corroborate the theoretical predictions, a new data-processing method based on dynamic programming is proposed to identify and measure multiple distinct equilibrium states from observed data. Agent-based simulations are conducted to generate examples of such data, and to verify the formulas. Numerical results show that (i) the proposed measurement method works well in identifying the distinct equilibria, and (ii) the vehicle swap strategy works quite effectively in mitigating the wild goose chase phenomenon. [ABSTRACT FROM AUTHOR]

The frequency response analysis describes the steady-state responses of a system to sinusoidal inputs at different frequencies, providing control engineers with an effective tool for designing control systems in the frequency domain. However, conducting this analysis for closed-loop reset systems is challenging due to system nonlinearity. This paper addresses this challenge through two key contributions. First, it introduces novel analysis methods for both open-loop and closed-loop reset control systems at steady states. These methods decompose the frequency responses of reset systems into base-linear and nonlinear components. Second, building upon this analysis, the paper develops closed-loop higher-order sinusoidal-input describing functions for reset control systems at steady states. These functions facilitate the analysis of frequency-domain properties, establish a connection between open-loop and closed-loop analysis. The accuracy and effectiveness of the proposed methods are successfully validated through simulations and experiments conducted on a reset Proportional–Integral–Derivative (PID) controlled precision motion system. • Current Describing function and Higher-order Sinusoidal-Input Describing Function (HOSIDF) analysis for closed-loop reset control systems are inaccurate. • The new theory provides insights that outputs of open-loop and closed-loop reset control systems under sinusoidal inputs can be analytically separated into their base-linear outputs and pulse-based nonlinear elements. • The proposed HOSIDF analysis rectifies the conservative assumption in previous HOSIDF analysis. • The closed-loop HOSIDF enables sensitivity function analysis, including higher-order harmonics. • The relation between open-loop and closed-loop analysis provide frequency-domain tools for future reset control system design. [ABSTRACT FROM AUTHOR]

A promising magnetic fusion steady state reactor is Chinese Fusion Engineering Testing Reactor (CFETR) and a different power conversion system is required than tokamak reactor. The control and utilization of high outlet temperature and thermal power generated by the fusion reactor efficiently are the main challenges in the field of thermo-fusion technology. An efficient and optimized power conversion system is an urge for the thermo-fusion energy system with a candidate working fluid under high temperature and pressure. Five cycle topologies based on the Brayton cycle have been designed such a s multi stage expansion and recompression cycle with intercooling, recompression cycle with intercooling, partial expansion with multistage compression, partial expansion and partial recompression with cooling across range of turbine and compressor inlet temperatures. Brayton cycle with different system configurations have been simulated with He-gas and supercritical Carbon Dioxide (CO 2) to conceive high outlet temperature of CFETR about 500 °C and thermal power of 200 MW th for better thermal performance by using REFPROP, EES and analytical model has been developed with MATLAB. The supercritical CO 2 has better thermal performance about 36.18 % as compared to He-gas has 29.81 % under same thermal conditions. The Schematic-I with addition of preheat and recompression enhance the thermal performance about 2 % and has been proposed for CFETR. The effect of change in pressure of the system, effect of the working fluid, isentropic efficiency, heat rate and back to work ratio on the thermal performance and network output have been analyzed and optimized based on analytical model with the MATLAB. The system net power is increased from 69.20 MW to 79.71 MW, heat rejected by the system is decreased from 134.46 MW to 127.06 MW and thermal performance is increased about 34.62 %–39.85 % with pressure from 24 MPa to 28 MPa. Using multi stage expansion and recompression cycle with intercooling instead of other topologies can improve the thermal performance up to 6.1 % depends upon the operation conditions and working fluid. The heat rate of the system decreased while back work ratio increased with the pressure and it reveal that calculations are correct. • The steady state Chinese Fusion Engineering Testing Reactor (CFETR) is a promising candidate to meet world energy demands. • The control and utilization of high outlet temperature and thermal power are main challenges in field of thermo-fusion technology. • SCO 2 Brayton cycle with multistage expansion, compression and intercooling has been designed and proposed for CFETR. [ABSTRACT FROM AUTHOR]

[Display omitted] • A discretization method to solve the steady state population balance is presented. • Nucleation, size independent growth and loose agglomeration are included. • A fixed point acceleration algorithm is applied with an optimal initial vector. • The crossed-secant acceleration method ensures the algorithm convergence. • The algorithm is suitable for coupling with multicompartment model and CFD. The present work focuses on the development of a performing numerical methodology to solve the steady state Population Balance Equation (PBE) including nucleation, independent size growth and loose agglomeration as crystallization mechanisms. The methodology is based on the solution of two PBEs: one for the isolated crystallites and one describing the loose agglomerates formation. Both are solved by a discretization method and only the last one is reformulated as a fixed point problem. The algorithm solving PBE for agglomeration includes the crossed-secant algorithm as a fixed point acceleration method. The numerical PBE solution method is first validated by comparison to analytical solutions and then applied to the neodymium oxalate precipitation in order to compare to experimental results in a wide range of operating conditions. The methodology is tested under highly restrictive numerical conditions: narrow tolerances, a large amount of points in the discretization scheme and a zero vector as initial condition. The crossed-secant method demonstrates to improve the robustness of the standard fixed point iterations by ensuring the convergence of the agglomerates PBE when penalizing conditions are applied and by reducing the number of iterations otherwise. In all cases, the developed methodology predicts accurately the crystal size distribution under the experimental uncertainty in a reasonable computation time and number of iterations. [ABSTRACT FROM AUTHOR]

The quantum Langevin equation as obtained from the independent-oscillator model describes a strong-coupling situation, devoid of the Born–Markov approximation that is employed in the context of the Gorini–Kossakowski–Sudarshan–Lindblad equation. The question we address is what happens when we implement such 'Born–Markov'-like approximations at the level of the quantum Langevin equation for a harmonic oscillator which carries a noise term satisfying a fluctuation–dissipation theorem. In this backdrop, we also comment on the rotating-wave approximation. • We discuss 'Born–Markov'-like limits of the quantum Langevin equation for an oscillator. • Equal-time position and velocity correlation functions are explicitly obtained. • We discuss the free-particle limit. • The rotating-wave approximation is discussed. [ABSTRACT FROM AUTHOR]

Prospective cardiac gating during MRI is hampered by electromagnetic induction from the rapidly switched imaging gradients into the ECG detection circuit. This is particularly challenging in small animal MRI, as higher heart rates combined with a smaller myocardial mass render routine ECG detection challenging. We have developed an open-hardware system that enables continuously running MRI scans to be performed in conjunction with cardio-respiratory gating such that the relaxation-weighted steady state magnetisation is maintained throughout the scan. This requires that the R-wave must be detected reliably even in the presence of rapidly switching gradients, and that data previously acquired that were corrupted by respiratory motion re-acquired. The accurately maintained steady-state magnetisation leads to an improvement in image quality and removes alterations in intensity that may otherwise occur throughout the cardiac cycle and impact upon automated image analysis. We describe the hardware required to enable this and demonstrate its application and robust performance using prospectively cardio-respiratory gated CINE imaging that is operated at a single, constant TR. Schematics, technical drawings, component listing and assembly instructions are made publicly available. [ABSTRACT FROM AUTHOR]

With the advantages of large flow capacity, low head, and high efficiency, the tubular turbine can well meet the demand for renewable resources. To obtain its synthetic characteristics in full operating conditions, model tests on both the steady state and transient process were designed and conducted in an ultra-low head bulb turbine. The similitude criteria, model test system, and test method were introduced; experiments on comprehensive steady-state and load-rejection conditions were performed; and the results were analyzed. Based on the steady-state test, the variation of flow, torque, and axial force with respect to the rotating speed, runner blade (RB) opening, and guide vane (GV) opening were revealed. Dynamic test results showed that the closing laws of GV and RB have an obvious influence on the quality of the transient process. Orthogonal optimization was used to acquire the optimal closing scheme of GVs and RBs when the turbine undergoes full load rejection under rated head conditions. Our test results provide a sound reference for the design and operation of tubular turbine units. • The synthetic performance of a double regulated bulb turbine was experimentally studied. • The characteristics of three key parameters in steady state were revealed and analyzed. • The external variation of different hydraulic parameters were explored and deeply analyzed. • The optimal closing scheme of regulating mechanism was acquired by using orthogonal optimization method. [ABSTRACT FROM AUTHOR]

[Display omitted] • The role of waste activated sludge (WAS) in anaerobic digestion was re-evaluated. • WAS provided extra microbes, creating a chance to reach microbial niche balance. • System resiliency developed when acidogenesis and acetogenesis over hydrolysis > 0.5. • Core species' acidogenesis and acetogenesis versatility assisted system resilience. There have been extensive applications of waste activated sludge (WAS) in anaerobic co-digestion (AcoD). Nonetheless, mechanisms through which AcoD systems maintain stability, particularly under nutrient-stressed conditions, are under-appreciated. In this study, the role of WAS in a nutrient-stressed WAS-food waste AcoD system was re-evaluated. Our findings demonstrated that WAS-based co-digestion increased methane production (by 20–60%) as WAS bolsters such systems' resilience via establishing a core niche-based microbial balance. The carbon utilization investigation suggested a microbial niche balance is attainable if two conditions are satisfied: 1) hydrolysis efficiency is greater than 50%; and 2) both the acidogenesis-to-hydrolysis and acetogenesis-to-hydrolysis efficiencies surpass 0.5. Metagenomic assembly genome (MAG) analysis indicated that the versatile metabolic characteristics strengthened the microbial niche balance, rendering the system resilient and efficient through a syntrophic mode, contributing to both acidogenesis and acetogenesis. The findings of this study provide new insights into the ecological effects of WAS on AcoD. [ABSTRACT FROM AUTHOR]

• Steady state description of crack propagation during DCB test with viscoelastic-viscoplastic-damage interface is achieved. • Macroscopic Gc vs da/dt master curves are obtained numerically for various adhesive layer rheological behavior. • A dual failure criterion is introduced to reproduce both toughtening and embrittlement phenomena. Adhesively bonded joints are known to suffer from creep and relaxation phenomena due to the viscous nature of the adhesive. These effects are detrimental to the durability of structural joints as they can lead to progressive and slow crack propagation rate phenomena and possible delayed failure. Master curve approaches are often used to assess the durability of structural assemblies, but the physical justification for such approaches requires additional investigation to more accurately assess the coupling between structural effects and the possible complex long-term rheological behaviour of the adhesive layer. Following similar approaches developed to study the steady-state crack propagation regime in bulk materials, an Eulerian description of crack propagation along a viscous adhesive layer during a double cantilever beam test is implemented. Taking into account viscoelastic-viscoplastic and various hardening rules, some master curves can be obtained describing the evolution of the crack propagation rate as a function of the stationary loading conditions. With such a model, the role of adhesive layer behaviour and joint geometry on crack propagation conditions can be discussed, as well as the applicability of such a master curve approach. [ABSTRACT FROM AUTHOR]

Most geohazards and industrial processes are essentially gravity-driven dense granular flows. Deep understanding of the effect of gravity on granular flow is of crucial importance in analyzing the evolution of planetary surfaces. By using a discrete element numerical simulation method, we obtain the evolutionary characteristics of velocity, volume fraction, shear rate and granular temperature during granular flow, and analyze the effect of gravity on the rheological behavior of granular materials. The results indicate that gravity significantly affects the flow characteristics of granular materials, especially in the case of large inclination angle. With the increase of gravity, the flow velocity, shear rate and granular temperature of the granular material tend to increase. When the inclination angle exceeds the critical value, the volume fraction of the granular system in the high gravity environment decreases significantly, while the inertia number increases. [ABSTRACT FROM AUTHOR]

This paper presents several steady-state neutron transport models which are used to determine the behaviour of the nuclear criticality incident that occurred at the Windscale Works in 1970. The transfer vessel involved in this incident contained two immiscible fissile liquids (an aqueous phase and an organic phase) which had been disturbed such that an emulsion layer formed between them. Infinite domains of the aqueous, organic, and emulsion phases were modelled to enable the understanding of the effects of nuclear data library, neutron transport code and material on the calculated kinetics data, effective multiplication factor and macroscopic neutron cross sections. Six possible configurations of the 1970 Windscale criticality incident were simulated using three-dimensional models in MCNP, two-dimensional models in academic research code EVENT, and one-dimensional models in a collision probability (CP) code. Quantities of interest, such as reactivity, scalar neutron flux, neutron absorption and production rates, and kinetics data are presented. System reactivity, mean neutron generation time and neutron absorption and production rates are shown to increase with increasing emulsion thickness, whereas the total scalar neutron flux is shown to decrease. It is determined that the volume of organic phase present during the transient was likely to be around 39.0 L, as the emulsion thickness required to reach criticality (6.5 cm) was within the range cited in the literature. EVENT and the CP code showed deficiencies when calculating the scalar neutron flux through the plenum gas at the top of the transfer vessel, with the CP code overestimating the total scalar neutron flux in the system by as much as 19 %. The intrinsic neutron source, subcritical multiplication and subcritical power of the system were computed using Monte Carlo simulations. It was shown, by use of the Hansen criteria, that the subcritical system was likely to be in a strong neutron source regime (such that stochastic variations in neutron population are negligible when regarding nuclear criticality transients). In addition, it was computed that a vessel containing 39.0 L of organic solvent had a subcritical power of 10.81 ± 0. 03 μ W. [ABSTRACT FROM AUTHOR]

Background: Dietary protein supports resistance exercise-induced anabolism primarily via the stimulation of protein synthesis rates. The indicator amino acid oxidation (IAAO) technique provides a noninvasive estimate of the protein intake that maximizes whole-body protein synthesis rates and net protein balance.Objective: We utilized IAAO to determine the maximal anabolic response to postexercise protein ingestion in resistance-trained men.Methods: Seven resistance-trained men (mean ± SD age 24 ± 3 y; weight 80 ± 9 kg; 11 ± 5% body fat; habitual protein intake 2.3 ± 0.6 g·kg-1·d-1) performed a bout of whole-body resistance exercise prior to ingesting hourly mixed meals, which provided a variable amount of protein (0.20-3.00 g·kg-1·d-1) as crystalline amino acids modeled after egg protein. Steady-state protein kinetics were modeled with oral l-[1-13C]-phenylalanine. Breath and urine samples were taken at isotopic steady state to determine phenylalanine flux (PheRa), phenylalanine excretion (F13CO2; reciprocal of protein synthesis), and net balance (protein synthesis - PheRa). Total amino acid oxidation was estimated from the ratio of urinary urea and creatinine.Results: Mixed model biphasic linear regression revealed a plateau in F13CO2 (mean: 2.00; 95% CI: 1.62, 2.38 g protein·kg-1·d-1) (r2 = 0.64; P ˂ 0.01) and in net balance (mean: 2.01; 95% CI: 1.44, 2.57 g protein·kg-1·d-1) (r2 = 0.63; P ˂ 0.01). Ratios of urinary urea and creatinine concentrations increased linearly (r = 0.84; P ˂ 0.01) across the range of protein intakes.Conclusions: A breakpoint protein intake of ∼2.0 g·kg-1·d-1, which maximized whole-body anabolism in resistance-trained men after exercise, is greater than previous IAAO-derived estimates for nonexercising men and is at the upper range of current general protein recommendations for athletes. The capacity to enhance whole-body net balance may be greater than previously suggested to maximize muscle protein synthesis in resistance-trained athletes accustomed to a high habitual protein intake. This trial was registered at clinicaltrials.gov as NCT03696264. [ABSTRACT FROM AUTHOR]

Continuum description of particle-fluid flows is of fundamental importance. In the past, various averaging methods were developed to derive local quantities directly from particle scale information. However, it is not clear if the long-sought resolution-independence of the local quantities exists. Here, using a discrete element method, a statistical analysis is conducted for a gas-solid fluidized bed of monodispersed coarse particles under various conditions. The mean free path and time are first examined with the variation of inlet gas velocity. Then, the particle motion is analyzed according to the Langevin equation and it is revealed that the motion of individual particles in the driven system follows the fluctuation-dissipation relation. Finally, the particle collisional frequency and velocity distribution are analyzed. These distributions can achieve a steady state. The particle collisional frequency distribution deviates from the Gaussian distribution noticeably at high gas velocities. These findings lead to a better understanding of particle motion in a gas-solid fluidized bed and support the seeking of resolution-independent local quantities with averaging methods. Unlabelled Image • A statistical and theoretical analysis is conducted for the motion of particles. • Mean free time and path are quantified for different energy input levels. • Random particle motion is examined according to the Langevin equation. • Particle collisional frequency and velocity distributions are investigated. • The evidence show that resolution-independent local quantities could be attained. [ABSTRACT FROM AUTHOR]

The steady state is expected when applying severe plastic deformation (SPD) techniques to process metals. In this study, we propose a method to study the steady state regarding the microstructural features and the mechanical properties, which are verified by the experimental results. More importantly, the initial state of as-prepared metal depending mainly on the processing conditions is critical for the subsequent constitutive relations. Within the framework of dislocation-based crystal plasticity, it is revealed that the dislocation density and flow stress will not change during further deformation when the initial dislocation density is equal to the steady-state value under the loading conditions. In addition, if the initial dislocation density is larger or smaller than the steady-state value, then the dislocation density and flow stress will decrease or increase with increasing strain, and tend to approach the steady-state value. These mechanisms provide not only a physical interpretation for various experimental observations such as near-perfect elastoplasticity, strain hardening and strain softening, but also insightful guidance for investigating the strengthening mechanisms in gradient nano-grained metal produced by SPD. • A general method is proposed to study the steady state during severe plastic deformation. • The crystal plasticity framework is developed to reveal the effect of initial states of metal on mechanical properties. • When ρ 0 = ρ s , the dislocation density and flow stress will not change during further deformation. • When ρ 0 > ρ s or ρ 0 < ρ s , the dislocation density and flow stress will decrease or increase with increasing strain, and approach the steady state. • The guidance is provided for investigating the strengthening mechanisms in gradient nano-grained metal. [ABSTRACT FROM AUTHOR]

This paper reported a semi-analytical method (SAM)-fast Fourier transform (FFT) based model for three-dimensional (3D) steady-state elastodynamic frictional contact of an elastic ellipsoid sliding on an elastic half-space with a constant sliding velocity. The frequency response functions (FRFs) and their conversion into influence coefficients (ICs) for displacements and stresses in an elastic half-space are analytically derived pertaining to generalized normal and tangential forces. Fast numerical techniques used are based on the conjugate gradient method (CGM) for obtaining unknown pressure distribution in the contact interface, and the discrete convolution-fast Fourier transform (DC-FFT) algorithm for calculating displacements and stresses. The proposed SAM-FFT based model is employed to investigate the effects of friction, sliding velocity, and Young's modulus on contact pressure, surface deformation and sub-surface von Mises stress. A transition map, supported by appropriate limits of friction coefficient and sliding velocity, is constructed to determine whether the location of maximum von Mises stress to appear beneath the contact surface or in the contact surface. It deserves mentioning that the elastodynamic effect becomes more profound if the sliding velocity is higher than 0.4 times of shear wave speed, which corresponds to a sliding velocity of 1300 m/s for steel materials (shear wave speed ∼3250 m/s), or 60 m/s for a soil foundation (shear wave speed ∼150 m/s). [ABSTRACT FROM AUTHOR]

Different materials would exhibit discrepant behaviors of radiation tolerance under energetic particle irradiation, due to the effect of intrinsic features (like defect migration energy and sink strength of grain boundaries) and extrinsic conditions (like irradiation rate and temperature) on defect accumulation. We wonder what the general rules of radiation tolerance are in body-centered cube (BCC) transition metals. Based on the steady state chemical rate theory, the influence of these intrinsic features and extrinsic conditions on vacancy accumulation is thus investigated in typical BCC metals including V, Cr, Fe, Nb, Mo, Ta and W. It shows that V, Cr, Fe and Nb exhibit obvious advantage in radiation resistance than that of Ta, Mo and W under typical service conditions, due to their higher vacancy diffusivities. In addition, the smaller grain size and lower irradiation rate, the higher anti-irradiation ability of BCC metals. Therefore, we propose that, under practical irradiation rates and temperatures, BCC metals with low vacancy migration energy and small grain size should be recommended in the selection of new nuclear materials, at least in the view of steady state. [ABSTRACT FROM AUTHOR]

• Slow increase of Δp (creep) during steady state is caused by accumulation of oil. • Creep is most pronounced for highly efficient filter media. • Different steady states for pre-saturated and initially dry filters. • Temporarily reduced air flows might result in pre-saturated steady states. This paper addresses the phenomenon of a slow Δ p increase ("creep") sometimes observed in mist filters during their so-called steady-state operation, especially at relatively high flow rates and aerosol loads (Kolb et al., 2017). This creep phenomenon draws into question the concept of steady state and awaits a physical explanation on the basis of more systematic data. The present study was performed with conventional glass microfiber filter media at filter face velocities in the range of 1–70 cm/s, using submicron oil aerosol at loading rates up to 1.1 g/(m2 s). Experiments started either with a dry filter (designated as S 0 = 0, where S stands for the liquid saturation level), or with a completely pre-saturated filter (designated as S 0 = 1). The S 0 = 0 runs reached "steady state" (defined here as the onset of drainage) after approximately 0.3 h and were then loaded continually for another 100 h. Runs starting at S 0 = 1 reached a steady state very quickly. With regard to Δ p, all filters featured Δ p creep when starting from S 0 = 0. For coarse filter grades, Δ p creep effectively ended in less than 40 h at moderate flow velocities; finer grades crept further and did not stop creeping within any reasonable loading time. When starting from S 0 = 1, a steady Δ p endpoint was reached rapidly, but was considerably higher than the level attained by creep. It was further shown that creep is associated with a slow increase in the saturation level and that S approached the (higher) level of pre-saturated filters. The increase in S during creep was associated with the formation of additional fine oil channels. Conversely, oil channels were completely absent in pre-saturated filters and the liquid was uniformly dispersed. Using simple theoretical considerations for flow in porous media, the observed differences in Δ p are explained in part by the difference in S between S 0 = 0 and S 0 = 1 filters, and in additionally also by taking into account the different liquid distribution patterns. We conclude that the onset of drainage under steady external conditions – the stage conventionally viewed as the beginning of steady-state operation – does not automatically represent an internal steady state with regard to saturation levels or pressure drop; and presumably also not for the oil distribution pattern. The internal saturation reaches a stable endpoint sooner than the pressure drop, which may continue to creep for the lifetime of the filter. Of and when a transition from channel patterns to homogeneous oil distribution occurs during steady operation is not known. However, the transition can be forced rather quickly by operating the filter intermittently at a very low flow velocity. [ABSTRACT FROM AUTHOR]

• The proposed kinetic model explains the trigger effect of N-acetylaspartate behavior. • Substrate inhibition is a necessary factor of N-acetylaspartate autostabilization. • N-acetylaspartate's "anti-peak" causes a wave of its hydrolysis products. A kinetic model of the process response of nervous tissue to an external signal stimulus is proposed. The model is based on the multistage and non-linear nature of the dynamic process of changes of N-acetylaspartate concentration. The existence of multiple steady states explains the trigger effect of the system. The effect of substrate inhibition for this system was studied as a necessary factor of N-acetylaspartate's autostabilization as a key metabolite in the brain. The appearance of N-acetylaspartate's "anti-peak" causes a wave of its hydrolysis products, such as aspartic acid and acetic acid. [ABSTRACT FROM AUTHOR]

Abstract The local existence and stability of non-constant positive steady states for the Holling–Tanner predator–prey model with prey-taxis was discussed by Wang et al. (2017) through local bifurcation analysis. It is our purpose in this paper to make a detailed description for the structure of the set of the non-constant steady states. We will prove a global bifurcation theorem by treating prey-taxis as a bifurcation parameter, which gives the existence of non-constant steady states under a rather natural condition. A priori estimates for steady state solutions will play a key role in the proof. In addition, the stability results for the homogeneous equilibrium will extend to the case that the derivative of prey's functional response with prey is positive, and it is found that attractive prey-taxis can stabilize homogeneous equilibrium even diffusion-driven instability has occurred. [ABSTRACT FROM AUTHOR]

Abstract A three dimensional model for solving steady state heat conduction in a semi-infinite domain containing an elementary cuboidal inhomogeneity is established in this paper. A set of analytical formulas for steady state heat conduction in a full space with an embedded cuboidal inclusion is derived. The temperature field of a half space distributed with arbitrarily shaped inhomogeneities is then obtained via the application of numerical discretization and the method of images. Benchmark comparisons involving a cuboidal/ellipsoidal inhomogeneity and double-inhomogeneity particle with the results produced by the finite element method (FEM) are conducted. Good agreements between the results of the two methods demonstrate the effectiveness and capability of the proposed model. Further, a case of heterogeneous material containing arrayed inhomogeneities is studied to explore the disturbance and interaction of the temperature field due to distributed inhomogeneities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Considering reactions in a zeolite via KMC simulation for the first time. • Describing the coupling of various processes in a zeolite for the first time. • Revealing the mesoscale structure of an adsorbate shell plus an inaccessible core. • Proposing a simulation approach to evaluate the channel utilization. • Discussing the manipulation of the mesoscale structure and the channel utilization. Abstract Complex distribution of adsorbates can emerge in heterogeneous catalysis due to the compromise among different mechanisms (showing different tendencies of structural evolution) associated with different processes. On two-dimensional catalyst surfaces, all the surfaces are exposed to the gas reservoir (and thus adsorption and desorption processes are accessible to all the surfaces), and we have investigated the effects of adsorption, desorption, diffusion, and reactions on the adlayer structure, and revealed the mechanisms (Huang and Li, 2016). However, in zeolites, only the entrances (or exits) of the pore channels are exposed to the gas reservoir (and thus adsorption and desorption processes are limited there), so the mesoscale behavior might be somewhat different. In this work we explore the influence of adsorption, desorption, diffusion, and reactions on the adsorbate distribution in the ZSM-5 zeolite using kinetic Monte Carlo simulations. Complex distributions of adsorbates (nonlinearly gradient, showing apparent adsorbate shells in some cases) have been revealed, and the channel utilization has been evaluated. The approach and results might be useful to catalyst design, especially determining the optimal thickness of zeolite on a catalyst particle (pellet), since the channel utilization is a measure of effective fraction of the catalyst and is correlated with the practical efficiency of catalysis. [ABSTRACT FROM AUTHOR]

Abstract The Organic Rankine Cycle (ORC) driven by low-grade energy can operate in off-grid mode. Here, we report the steady and transient characteristics of an ORC system. A single screw expander and a synchronous generator convert mechanical power to electricity. A lamp array simulates the variable external loads. The quality parameters including electric frequency, electric power and effective voltage are measured by a power meter. We show that at setting frequency of 50 Hz, the maximum system efficiency can be reached when the external load is not larger than the ORC power capacity. The expander isentropic efficiency is above 80% for the vapor superheating of 5–10 K at expander inlet. A control strategy is proposed to achieve better system performance under varied heat source and environment conditions. By use of residual frequency and adjusting pumping frequency, the vapor pressure at expander inlet can be automatically adjusted to reach the optimal value. Transient tests indicate that the electric quality is insensitive to the step change of external loads and heat/cold sources parameters. The thermohydraulic parameters are self-adapted to the change of external parameters. This work provides a self-adapting strategy for ORC operation at varied heat/cold source parameters. Highlights • The steady and transient operation characteristics of an ORC system are investigated. • A single screw expander and a synchronous generator are included in the system. • The electric frequency of 50 Hz is reached if external load is not larger than ORC capacity. • Electric energy quality parameters are insensitive to the step change of external parameters. [ABSTRACT FROM AUTHOR]

• An analytical model is developed for inter-aquifer, abandoned-well leakage. • A well injected to the confined aquifer is considered in the leakage model. • A thinner confined aquifer will lead to a higher abandoned well leakage rate. A non-plugged abandoned well may cause unwanted flows and solute transport between aquifers. This research provides a novel analytical model to calculate the leakage rate in an abandoned well between a confined aquifer and an unconfined aquifer under steady-state flow conditions. The abandoned well is treated as a passive preferential flow channel connecting a confined aquifer receiving injection from a separate well and an overlying unconfined aquifer; an impermeable aquiclude separates the two aquifers. A closed-form analytical solution for the steady-state leakage rate through an abandoned well is derived. The concerned abandoned well in this study fully penetrates the receiving unconfined aquifer but only penetrates the ceiling of the injecting confined aquifer with a very small screen length (with respect to the confined aquifer thickness). The injection well is sealed from the receiving unconfined aquifer and fully penetrating in the injecting confined aquifer. The solution developed in this study is compared with a previous solution by Avci (1994) (Avci, 1994. Evaluation of flow leakage through abandoned wells and boreholes. Water Resources Research, 30 (9), 2565–2578). Compared to Avci (1994), this research has two different assumptions: (1) The Avci solution assumed that the leakage effect occurs between two confined aquifers, and leakage concerned in this research occurs between an injecting confined aquifer and a receiving unconfined aquifer. (2) The abandoned well in the Avci (1994) solution fully penetrates both the receiving and injecting confined aquifers, while the abandoned well in this research fully penetrates the receiving unconfined aquifer but only penetrates the ceiling of the injecting confined aquifer with a minor screen length. In both this study and the Avci (1994), the injecting well is isolated from the receiving aquifer and fully penetrating in the injecting aquifer. The results show that the two solutions have similarities in thin confined aquifers but are much different in relatively thick confined aquifers (with thickness greater than 10 m). Using the Sobol method for global sensitivity analysis, we tested controls of the hydraulic conductivity ratio between confined and unconfined aquifers, the transmissivity of the confined aquifer over the injection rate per unit screen length, and the aquifer thickness on model performance. The results show that the model is most sensitive to the transmissivity of the confined aquifer over the injection rate per unit screen length. This research can be applied in multiple applications, such as modeling the leakage effect among two aquifers involving stormwater recharge and using a monitoring well to detect the existence of abandoned wells when the abandoned wells are not visible on the surface or not documented, among others. [ABSTRACT FROM AUTHOR]

This paper presents the development and verification of a collision probability (CP) code, capable of modelling neutron transport in one-dimensional slabs and axially heterogeneous cylinders with varying radii. The CP code is used to model layered systems of aqueous and organic plutonium nitrate, as process criticality accidents are more likely to occur in these systems compared to dry systems. The use of the CP code is desired as it offers a computationally inexpensive method for calculating neutron transport when compared to higher fidelity codes such as MCNP. For slab geometries, the CP code can be used effectively, given they contain at least 0.7 g cm−2 plutonium. The approximation employed by the CP code to model heterogeneous cylinders overestimated the rate of radial neutron leakage such that vessels with radii of 30.0 cm could not reliably calculate reactivity to within 1 $ of MCNP. Increasing the radii to 40.0 cm improved the accuracy of the CP code to within 1 $ of MCNP for systems containing at least 2.75 kg plutonium. The error in the CP code increased when used to model cylindrical geometries with dished ends and complete vessels with dished ends, such that systems with large dished ends and low plutonium content should be avoided. As a simple, neutronics based model, the CP code could be used as part of rough order of magnitude calculations for criticality transients, where high levels of accuracy are not required, given that potential errors in results have been previously identified. [ABSTRACT FROM AUTHOR]

This pilot study explores the suitability of thermoluminescence (TL) of quartzites from exhumed metamorphic rocks of the Peloponnese (Greece) for thermometry and thermochronometry. Specifically, four quartz samples with very low radioelement content were extracted from large quartz lumps exposed at the surface of extensive quartzite rocks that make up the metamoprhic core of the central and southern Peloponnese The samples were submitted to a series of experiments and methods of analysis involving the sensitization of the 110 °C TL peak, fractional glow (via initial rise), TL-signal deconvolution, and characterization of signal response to large doses. The sensitization of the 110 °C TL trap was used to monitor the peak metamoprhic temperature of the quartzites. This is a novelty employed for the first time in this work. The sensitization of the 110 °C TL trap points to peak metamorphic temperatures which seem to be in agreement with independent thermometric data specific to these rocks. TL deconvolution analysis returned at least three traps which exhibit variable geological stabilities (lifetimes) but high saturation levels. Our studies demonstrate that TL from these rocks has the potential to be used for both thermometry and thermochronometry. Nevertheless, the very low dose rates associated with these quartzes qualify the here estimated equivalent doses for the estimation of maximum cooling ages only at this stage. • Exploring thermoluminescence of quartzites for thermometry and thermochronometry. • The sensitization of the 110 °C TL trap points at peak metamorphic temperatures. • TL peak analysis revealed at least three traps with variable geological lifetimes. • Using the dose rate, the equivalent doses ages lead to minimum closure temperatures. [ABSTRACT FROM AUTHOR]

Mining operations produce large quantities of tailings that must be handled and stored safely in a technical framework that reconciles economic restrictions and environmental sustainability. Unfortunately, the history of tailings deposits is marked by episodes of catastrophic failures, which is confirmed by the recent tailings dam collapses that occurred in Canada (Mount Polley), Australia (Cadia) and Brazil (Samarco and Brumadinio). Due to this alarming empirical evidence left by the mining industry worldwide, there is international concern and a demand to build these deposits safely from every point of view. In this scenario, the main geotechnical parameter that requires significant attention is the undrained residual shear strength, which is crucial to ensure the physical stability of a tailings dam. The critical state soil mechanic (CSSM) and/or the steady state of deformation provide the conceptual framework for evaluating this strength mobilized by particulate materials. However, despite the fact that these concepts are long established, some important aspects of soil behavior have not been clearly incorporated, which can seriously affect the estimation of the residual undrained shear strength. In this paper the effects of strain rate and reorientation of platy particles in fine-grained soils, the existence of a quasi-steady state (condition of minimum undrained strength) in sandy soils and the limitations of the state parameter are analyzed and discussed. In this context, the main goals are to minimize misjudgments in the estimation of the undrained strength and to introduce an alternative tool, the flow index, I f , to evaluate the susceptibility of the occurrence of flow failure in tailings dams. • The history of tailings deposits is marked by episodes of failures, many of them associated with the occurrence of static liquefaction. • The critical state soil mechanic (steady state of deformation) provides the framework to evaluate static liquefaction. • It is shown that the critical state is more suitable for clayey soils, while the steady state is more useful in sandy soils. • The state parameters do not consider the static shear stress, which in contractive states is responsible for triggering a flow failure. • An alternative state parameter based on the quasi-steady state and the static shear stress is proposed to identify flow failures. [ABSTRACT FROM AUTHOR]

Usually, it is very challenging to construct appropriate Lyapunov functionals for proving the global stability of age-structured models. In this paper, we propose an analytical approach to applying the Lyapunov direct method for such models. The novelty of this approach lies in successfully handling the two challenges when applying the method. On the one hand, according to the integral terms involved in the model, we propose an easy-to-follow way to determine the kernel functions in the Lyapunov functional candidate. On the other hand, we establish a new integral inequality, which is conducive to arranging the derivative of the functional so that it is easy to see whether the derivative is negative definite or negative semi-definite. As an application, we investigate the global stability of the endemic steady state of an age-structured epidemic model with two infectious stages. Moreover, the Lyapunov functional obtained for the endemic steady state is also helpful for proving the global stability of the disease-free steady state and the persistence of the disease. [ABSTRACT FROM AUTHOR]

Abstract In biomedical optics, the diffusion model of biological tissue plays an important role. In the biological tissue of any multi-layer rectangular non-matching slab medium, under the rectangular boundary condition, based on the diffusion equation of light propagation in the biological medium, using the extrapolation boundary condition, the exact solution of the diffusion equation Green function of the light in any multi-layer rectangular medium of finite thickness is established and given, and the spatial resolution diffuse reflectivity and transmittance and time resolved diffuse reflectivity and transmittance are calculated in this paper. Different formulas for calculating transmittance are given. We use Monte Carlo to verify our model. The results show that our equation is in good agreement with Monte Carlo simulation. The equation can not only solve the problem of medium which is rectangular laterally, but also solve the problem that the x axis and y axis are infinite in transverse direction, and the medium is semi-infinite in longitudinal direction, and it can also solve the problem that the x, y and z coordinate axes are finite in size. So it's more universal. [ABSTRACT FROM AUTHOR]

Abstract The slab reheating process in a reheating furnace is a very energy intensive process with many operating parameters that can be optimized. Numerical methods are therefore applied to generate models which can be used in an optimization strategy. This paper presents the first step in the creation of these models: obtaining the boundary conditions for the slab model from a steady state model of the furnace. The slab heating process itself is a transient phenomenon and an accurate cross-sectional slab temperature cannot be obtained using a steady state model. The furnace however, operates in a narrow range of temperatures and steady state operation is a suitable approximation. The steady state model is calibrated with data from a working reheating furnace at the ArcelorMittal Gent site. The numerical results show a good agreement with the experimental data with an average relative error of 3.1%. This gives confidence in using this model to determine the furnace heating boundary conditions of the slab model which will be implemented in future work. [ABSTRACT FROM AUTHOR]

Highlights • New high voltage underground cables modeling approach including induced effects. • Calculation of induced voltages and currents due to nearby cables and sheaths. • Different types of sheaths connections and various short-circuit configurations. • Simulation tool that allows the automatic generation of multiple coupling circuits. • Validated by expected theoretical data and compared to ATP simulator. Abstract This paper presents a novel approach to the modeling of high voltage underground cables. Its main contribution is that it considers induced effects. Indeed, it incorporates the estimate of induced voltages and currents in cable sheaths in steady state due to the nearby cables and sheaths, for different types of sheaths connections and for various single-phase short-circuit configurations and three-phase short-circuits. Furthermore, it allows multiple circuits to be coupled automatically in a simple way. An intuitive and friendly simulation tool has been implemented that allows the automatic generation of multiple coupling circuits and to calculate all these induced effects caused by the connection of the sheaths and the distance between cables. It has been validated by comparing it with the expected theoretical data and to other simulators with satisfactory results. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this paper is to study the existence of steady state in a linear cross-diffusion predator–prey model with Beddington–DeAngelis functional response. The proofs mainly rely on Fixed point index theory and analytical techniques. [ABSTRACT FROM AUTHOR]

Abstract Understanding of the microstructural evolution and equilibrium grain size development during steady state tertiary flow is essential in order to improve our knowledge of ice and rock deformation. This contribution presents results from in situ transmitted light deformation experiments of natural glacier ice, with the development of the microstructure in a tertiary flow regime. We conducted one relative slower (1 × 10 − 6 1/s) and two relative faster-strain rate (2 × 10 − 6 1/s) pure shear experiments at −10 °C, up to a shortening of ∼57%. Microstructure development was followed by time-lapse observations, and two new microstructure-based indicators, the 'seeding rate' and the 'microstructure activity', were introduced to evaluate whether a steady-state was reached. These indicate that a steady state was only reached in the two faster strain rate experiments. In contrast, during a slow deformation there is insufficient seeding of new grains to enable continuous recovery, and there is a bimodal grain size distribution. These results are explained by stress concentrations within grains. Particularly where basal planes are in unfavourable orientations for basal slip (hard glide orientation) coinciding with the development of a bimodal grain size distribution. In the case of bimodal grain size distributions the use of a stabilised mean grain size as a stress piezometer as a criterion for steady state should be handled with caution. Highlights • Mean grain size is not a reliable indicator for steady state. • 'Seeding rate' and 'microstructure activity' introduced as steady state indicators. • Concentration of stress on 'hard' grains can impede steady state in slow strain rate. [ABSTRACT FROM AUTHOR]

Abstract Models for weathering and regolith formation are generally built on the assumption of constant rates of water advection in the zone of water-saturated pores, and constant water content of those pores, but it is common that weathering occurs in the water-unsaturated zone where lateral flow occurs. Thus, water content in pores varies with depth. Here we model mineral weathering profiles while accounting for depth-dependent water content. Like previous models, a mineral equilibrates with water over a length ξ that depends on dissolution and advection rates, but a new lengthscale λ is introduced to describe the decrease of water content with depth. Steady states of the regolith thickness can be attained for any finite λ and non-zero velocity v E of erosion at the land surface. The type of mineral depletion profile developed over geological timescales depends on coupling between weathering and erosion: for slow erosion, a completely developed profile (CDP) is observed, in which the mineral-depleted zone at the top of the regolith has thickness of order λ ; as v E increases, there is a transition to an incompletely developed profile (IDP), in which partial mineral depletion at the land surface is constrained to a narrow range of velocities; when v E exceeds the advance rate of weathering under far from equilibrium conditions, the profile transitions to an unstable regime that exposes bedrock. In general, the reaction front (RF) thickness and the velocity where CPD transitions to IDP depend on the interplay of both water infiltration and chemical equilibration over the timescale of water residence in regolith. The RF thickness roughly equals a correlation length χ defined as half the harmonic average of ξ and λ. In cases of limited water infiltration, water-mineral equilibration is achieved within the length λ , so that the RF thickness is controlled by hydrological properties and is independent of dissolution and advection rates. In the opposite endmember, water infiltrates to large depths and the effects of physical and chemical parameters on RF thickness are the same as in previous geochemical models. The relaxation time for reaching a steady state is shown to be ∼ χ / v E . We discuss the effects of physical and chemical parameters in CDPs and IDPs in those endmembers and show an application to a CDP in granitic regolith. [ABSTRACT FROM AUTHOR]

Abstract Gas concentration profiles of carbon dioxide (CO 2), oxygen (O 2), methane (CH 4) and nitrogen (N 2) are usually measured during tests investigating microbial aerobic methane oxidation in landfill cover. However, only qualitative/limited information can be obtained from gas concentration profiles by existing methods. A new method is proposed to determine methane oxidation in soil quantitatively and comprehensively, including methane oxidation efficiency, stoichiometry, gas transfer mechanism, methane generation rate and gas reaction rate distributions. Governing equations are established based on mass balance for O 2 , CO 2 , CH 4 and N 2 at one-dimensional and steady-state condition. Gas transfer mechanisms considered include gas diffusion, advection and gas reaction. The method utilizes gas concentration profiles to determine gas diffusion for each gas component according to Fick's law. Then gas advections and reactions can be determined by mass balance. The method is validated by (i) published soil column tests investigating methane oxidation and (ii) a calibrated numerical model based on a selected soil column test. The new method is capable of determining methane oxidation efficiency, stoichiometry, gas transfer mechanism, methane generation rate and gas reaction rate distributions for CH 4 , CO 2 and O 2. Graphical abstract Unlabelled Image Highlights • A new analytical method for determining methane (CH 4) oxidation in landfill cover • The method determines CH 4 oxidation in soil quantitatively and comprehensively. • The method requires gas concentration profiles and gas diffusion coefficient in soil. • Calculated CH 4 oxidation rate and generation rate increase as tortuosity increases. • Calculated CH 4 oxidation efficiency and stoichiometry are independent of tortuosity. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a methodology for leak detection and isolation (LDI) in pipelines based on data fusion from two approaches: a steady-state estimation and an Extended Kalman Filter (EKF). The proposed method considers only pressure head and flow rate measurements at the pipeline ends, which contain intrinsic sensor and process noise. The LDI system is tested in real-time by using an USB data acquisition device that is implemented in MATLAB environment. The effectiveness of the method is analyzed by considering: online detection, location as well as quantification of non-concurrent leaks at different positions. The leak estimation error average is less than 1% of the flow rate and less than 3% in the leakage position. Furthermore, the incorporation of a steady-state estimation shows that the solution of the LDI problem has improved significantly with respect to the one that only considers the EKF estimation. An experimental analysis was also performed on the effectiveness of the proposed approach for different sampling rates and for different leakage positions. Highlights • This paper focuses on improving some practical limitations in the real-time implementation of an Extended Kalman Filter (EKF) for leak detection and isolation (LDI) in pipelines. • Results of the diagnosis program tests in an experimental pipeline are included. The EKF was tuned according to the uncertainty of the available sensors. • The proposed LDI scheme considers the incorporation of the steady-state solution of the dynamic model into EKF outputs to improve the estimates of the leak parameters. • The leak-detection system considers different reliability regions according to the sample time. [ABSTRACT FROM AUTHOR]

Highlights • Whether the optimal operation of dividing-wall column (DWC) can be realized without adjusting vapor split ratio can be determined. • For ternary separation, dilution effect in DWC is proposed. It reveals DWC may need online optimization. • Feedback is used for the online optimization of DWC. The relation between degree of closeness (between energy consumption (Q) and Q min) and setpoint range of manipulated variable/control variable can be acquired. • Disturbance and implementation error can be handled by using the proposed method. Abstract Optimal operation indicates energy consumption (Q) close to its Q min while product specifications are satisfied. Generally, for DWC, there are two manipulated variables (MVs) to keep Q close to Q min. Therefore, there are three operation mode, which are two MVs online optimization (Mode 2), single MV online optimization (Mode 1) and two MVs fixed (Mode 0). A steady-state analysis method for optimal operation of DWC with disturbance is presented. In the method, whether optimal operation can be achieved under Mode 0/ Mode 1 can be determined. Feedback is used for the online optimization under Mode 1 and Mode 2. The relation between degree of closeness (between Q and Q min) and setpoint range of manipulated variable/control variable can be acquired. For ternary separation, dilution effect in DWC is proposed. It reveals DWC may need online optimization. Implementation error is discussed. Disturbance and implementation error can be handled by using the proposed method simultaneously. The important ternary separation of benzene, toluene, and o-xylene in industry is used as an example to illustrate the method. In the case, optimal operation can be realized under Mode 1 and Mode 2. [ABSTRACT FROM AUTHOR]

Highlights • Experimental research on microencapsulated phase change material. • Steady and non-steady state measurements of dynamic viscosity. • Results for shear rate range 0.0132–132.00 s−1 and temperature 10–50 °C. • Non-Newtonian behavior observed (with exception of low mass fraction of mPCM). • In non-steady state heating a visible influence of phase change process on dynamic viscosity is observed. Abstract The use of microencapsulated phase change materials (mPCM) is one of the most efficient ways of storing thermal energy. Microencapsulated phase change slurry (mPCM slurry) is formed when the microencapsulated phase change material is dispersed into the carrier fluid. The mPCM slurry can be used as a heat transfer medium. This paper details an experimental study that was performed to investigate rheological properties of microencapsulated phase change slurry (Micronal® DS 5039 X – water). Six samples of mPCM slurry were prepared with different mass ratios of mPCM to water, namely: 10:90, 30:70, 50:50, 70:30, 90:10, 100:0 (pure Micronal® DS 5039 X). The dynamic viscosity-shear rate curves were obtained for spindle speeds from 0.01 to 100 rpm (shear rate 0.0132–132.00 s−1 respectively). The steady state measurement of viscosity was carried out when the slurry reached constant temperatures, namely: 10.0; 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 40.0 and 50.0 °C. The dynamic viscosity of slurries increases with the mPCM concentration in dispersion rises. Only the sample of 10% mPCM may be considered as a Newtonian fluid within the test range (shear rate 0.0132–132.00 s−1). Increasing the shear rate ultimately causes viscosity to decrease down to the Newtonian plateau, where it seems to be constant. The higher the temperature of the slurry, the lower the shear rate value, after which the viscosity characteristic becomes linear or constant. The same principle applies to mass ratio. In vicinity of the melting point (about 25 °C) the phase change process of mPCM slurry does not influence the viscosity-shear rate characteristic behavior when steady state conditions are preserved. The non-steady state condition was also examined, more specifically, the temperature of the sample was increased continuously at a steady pace from 16 °C to 29 °C. This stage took 17 min with each data point collected at 15 s intervals. During a non-steady state temperature increase, near melting point, the viscosity of the slurry clearly departed from those values observed in steady states. It can therefore be concluded that around the melting point temperature, the phase change process of mPCM slurry influences the viscosity. [ABSTRACT FROM AUTHOR]

Highlights • A tool to predict asphalt pavement surface deterioration is developed. • The tool successfully predicts the steady state of pavement surface deterioration. • The onset of steady state of pavement surface deterioration is predicted. • A reduction of 40% to 50% of experimentation time is achieved. Abstract The laboratory simulation of asphalt pavement surface deterioration is usually a lengthy process. In this study, a predictive tool (or equation) was developed to calculate the steady state torque-based coefficient of friction (Tfr) and the onset of steady state. To this end, nonlinear regression was utilized and a Graphical User Interface (GUI) was built in MATLAB®. The purpose of the tool is to reduce experimentation time. Eight sets of data were used. Data was obtained from laboratory testing conducted on eight Job Mix Formulas (JMFs) of highway materials obtained from the State of Ohio. The data was collected using a power unit (or motor) attached to a newly developed asphalt polishing machine to detect surface deterioration. The experiment measures torque values that are directly related to friction values; the so called torque-based coefficients of friction. The main characteristic of the equation allows for calculating the steady state Tfr and the onset of steady state. This enables the experimenter to determine when steady state is reached at a desired tolerance during the test, thus reducing the time required for testing. It was concluded that testing time can be reduced significantly (a range of 40% to 50% savings), which may be received positively by Departments of Transportation and other highway material testing laboratories around the world. [ABSTRACT FROM AUTHOR]