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A new procedure for linearizing dynamic error, without using state transformation, and linearizing nonlinear terms has been presented. The nonlinear term in the error differential equation has been analyzed in terms of the dynamic error and then has been replaced in the matrix of error factors. With stabilizing this matrix, the differential equation can be linearized and the gains of the observer have been obtained in nonlinear terms of the estimated state and the actual output. In other words, utilizing nonlinear gain factors, the nonlinearity in the final form of differential equation can be removed, and thus, differential equation of dynamic error can be linearized. The required conditions for observer construction and the procedure for linearizing of dynamic error have thoroughly been presented in detail. The robustness of designed observer to Lipschitz constant has been studied, and the absolute robustness of observer has been proved. Additionally, robustness to uncertainty has been investigated, and finally, the results for a sample nonlinear Lipschitz system, in the absence and the presence of uncertainty, are elicited and presented. The extracted results have shown good ability of observer in state estimation of studied system in the presence and absence of uncertainty. Furthermore, the presented results proved absolute robustness of designed observer to Lipschitz nonlinearity.

Using supplementary cementitious materials in concrete attracted significant attention worldwide due to environmental benefits and the potential for enhancing concrete’s mechanical properties and durability. This study investigates the interaction effects of silica fume and ground granulated blast furnace slag on the behavior of normal and high-strength concrete regarding steel corrosion resistance, carbonation depth, and compressive strength. Fifty-two concrete specimens were prepared in four groups with different combinations of water-to-cementitious materials ratio (w/cm), slag content, and silica fume content and were tested. A method was employed to compare the corrosion initiation times of different concrete specimens. The results demonstrated that silica fume improves the concrete’s resistance to steel corrosion by enhancing the cement matrix’s density, strength, and durability. The specimen with a w/cm ratio of 0.3 containing 35% slag and 10% silica fume achieved a 33% reduction in carbonation depth and a compressive strength of 118 MPa, representing a 20% increase compared to the similar specimen without slag. Furthermore, the specimen with a w/cm ratio of 0.3 containing 35% slag and 15% silica fume exhibited a 44% increase in steel corrosion resistance compared to the similar specimen without silica fume. While optimizing the combined content of slag and silica fume, this study highlights that their individual effects are less significant than their combined effect when used as partial replacements for cement.

In the current study, elemental analysis and microscopic investigations were conducted to characterize the minerals present in an iron ore sample. The iron content was below 24%, with the dominant iron-bearing minerals being hematite and magnetite. Consequently, gravity and magnetic separation methods were employed to enhance the iron content. However, the processing results less than what was expecting due to incomplete sample characterization. The sample was further analyzed using quantitative X-ray diffraction analysis. This more comprehensive examination revealed additional iron-bearing minerals as goethite, ankerite, and limonite. The behavior of these minerals likely contributed to the unsuccessful separation process which was thoroughly explored in this article. Understanding the mineralogical composition of iron ores is paramount for optimizing processing operations and achieving successful outcomes.

Nowadays, one of the methods to prevent the progress of Alzheimer's disease (AD) is to prescribe compounds that inhibit the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Researchers are actively pursuing compounds, particularly of natural origin, that exhibit enhanced efficacy and reduced side effects. The inhibition of AChE and BChE using natural flavonoids represents a promising avenue for regulating AD. This study aims to identify alternative flavonoids capable of modulating AD by down-regulating AChE and BChE activity through a molecular docking approach. Molecular docking analysis identified Ginkgetin and Kolaflavanone as potent inhibitors of AChE and BChE, respectively, among the selected flavonoids. Asn87 and Ala127 involved in the interactions of AChE-Ginkgetin complex through conventional hydrogen bonds. While in the BChE-Kolaflavanone complex, Asn83, Ser79, Gln 47, and Ser287 are involved. In vitroanalysis further corroborated the inhibitory potential, with Ginkgetin exhibiting an IC50of 3.2 mM against AChE, and Kolaflavanone displaying an IC50of 3.6 mM against BChE. These findings underscore the potential of Ginkgetin and Kolaflavanone as candidate inhibitors for the treatment of AD through the inhibition of AChE and BChE enzymes. Nevertheless, additional in vitroand in vivostudies are imperative to validate the efficacy of these compounds.

We use an efficient molecular theory approach to study electrokinetic flow within a pH-responsive nanopore grafted with a polyelectrolyte (PE) brush. The flow rate, migration and convective conductance, electric potential and velocity fields, species distributions and the degree of ionization of the weak PE functional groups and nanopore selectivity are obtained and interpreted while considering pH-induced surface charges. The theory is generally based on writing the overall free energy of the system including the entropies arising from the conformations of flexible, excluded volume chains, the mixing of mobile species, electrostatic contribution, and the free energy due to the chemical acid–base equilibrium reactions. We demonstrate how, by controlling the bulk salt concentration, pH, surface grafting density, and PE drag coefficient, the flow inside the pore can be controlled. Generally, the flow rate gets enhanced upon decreasing pH, but the effect of salt concentration is more complex. As long as the pH is small (large), the flow rate decreases (increases) by increasing the salt concentration, while a nonmonotonic trend is evident at moderate pH values. We find that, when the PE drag coefficient is high (low), the flow rate decreases (increases) by increasing surface grafting density. For intermediate drag coefficients, the flow rate varies nonmonotonically with surface grafting density. It is observed that the convective ionic conductance obeys almost the same trend as the flow rate. It is also illustrated that the mean degree of ionization of the polymer chains and the migration ionic conductance enhance on increasing the background salt concentration, whereas the opposite is true for nanopore selectivity. However, when very low salt concentration is accompanied by a high pH value, there is a minimum in the nanopore selectivity. The present approach allows investigation of the application of PE-coated nanopores as smart nanovalves.

Over the past few years, the Optical Trapezoid Model (OPTRAM) has been widely used as a means for high-resolution mapping of surface soil moisture using optical satellite data. In this paper, we propose a new variant of OPTRAM that can map not only soil moisture, but also water bodies such as lakes and rivers. The proposed variant was tested using laboratory experimental data as well as Landsat-8 reflectance observations. Results showed the new OPTRAM variant has greater skill than the original variant in separating land and water pixels. In addition, the new variant showed less sensitivity to the model parameters, and hence, is less user dependent. To quantitatively examine the user-dependency of the model, we analyzed OPTRAM soil moisture based on Landsat-8 satellite images in California, where we varied the model parameters in a plausible range. The correlations of the resulting maps in terms of R2between two largely different sets of parameters were found in the range of 0.47-0.52 for the original variant and 0.67-0.76 for the new variant. Because some OPTRAM parameters can be quite uncertain, particularly in wet regions, the reduced sensitivity promises more consistent soil moisture estimates across the range of parameter choices.

The presence of polymer–particle interactions in composite materials leads to the formation of interfacial layers with physical properties significantly different from those of the polymer matrix and fillers. Mathematical modeling of the interfacial morphology in mixed matrix membranes (MMMs) not only considerably depends on the assumed interface thickness, but also is related to the applied modeling algorithm. In the current study, a new algorithm is developed to estimate the interface thickness based on findings of molecular dynamics and Monte Carlo simulations in the literature as well as the size and the loading of the particles. Moreover, effective permeability of the MMMs is predicted with no need to evaluate the permeability of the particles and the type of interfacial morphology by only adjusting the reduced permeability factor in the range of −0.5 to 1. On the basis of the proposed modeling approach, characteristic parameters of encapsulated particles by interfacial layer, β and γ, can be simply determined from the corresponding contour line of γ and β for the description of permeability through it. Initially, the effective permeability of composites comprising encapsulated particles by the interfacial layer is assessed by adjusting only one parameter after determining effective interface thickness. The comparison between the predictions and the reported experimental permeability data of 17 series of the MMMs confirmed that the accuracy of the modified Maxwell model based on the proposed modeling approach is more than 95% for more than 90% of the predictions, while the maximum average absolute relative error (AARE) is 8.3%.

Soil moisture (SM) is a key hydrologic state variable that is of significant importance for numerous Earth and environmental science applications that directly impact the global environment and human society. Potential applications include, but are not limited to, forecasting of weather and climate variability; prediction and monitoring of drought conditions; management and allocation of water resources; agricultural plant production and alleviation of famine; prevention of natural disasters such as wild fires, landslides, floods, and dust storms; or monitoring of ecosystem response to climate change. Because of the importance and wide‐ranging applicability of highly variable spatial and temporal SM information that links the water, energy, and carbon cycles, significant efforts and resources have been devoted in recent years to advance SM measurement and monitoring capabilities from the point to the global scales. This review encompasses recent advances and the state‐of‐the‐art of ground, proximal, and novel SM remote sensing techniques at various spatial and temporal scales and identifies critical future research needs and directions to further advance and optimize technology, analysis and retrieval methods, and the application of SM information to improve the understanding of critical zone moisture dynamics. Despite the impressive progress over the last decade, there are still many opportunities and needs to, for example, improve SM retrieval from remotely sensed optical, thermal, and microwave data and opportunities for novel applications of SM information for water resources management, sustainable environmental development, and food security. Recent soil moisture measurement and monitoring techniques and estimation models from the point to the global scales and their limitations are presentedThe importance and application of soil moisture information for various Earth and environmental sciences disciplines such as forecasting weather and climate variability, modeling hydrological processes, and predicting and monitoring extreme events and their impacts on the environment and human society are presented

In this study, TiO2nanoparticles were functionalized by grafting polymerization of methoxy poly(ethylene glycol) methacrylate (MPEG) onto the nanoparticle surface. Functionalized TiO2nanoparticle was used as nanofiller to prepare poly(vinyl alcohol) (PVA) based nanocomposite (NC) membranes through solution mixing method. The thermal and mechanical properties of PVA/PMPEG-TiO2membranes were improved compared to pristine PVA membrane due to well dispersion and high compatibility between the inorganic fillers and the polymer matrix. Gas permeation and selectivity properties of PVA/PMPEG-TiO2NC membranes with various TiO2contents were also studied for O2, N2, CH4and CO2. Gas permeability improvement was seen for studied gases, especially for CO2. In addition, the results showed higher CO2/N2selectivity up to 49.36% for 3 wt% TiO2containing NC membranes.

In the present work, the response surface method software was used with five measurement levels with three factors. These were applied for the optimization of operating parameters that affected gas separation performance of polyurethane–zeolite 3A, ZSM-5 mixed matrix membranes. The basis of the experiments was a rotatable central composite design (CCD). The three independent variables studied were: zeolite content (0–24 wt%), operating temperature (25–45 °C) and operating pressure (0.2–0.1 MPa). The effects of these three variables on the selectivity and permeability membranes were studied by the analysis of variance (ANOVA). Optimal conditions for the enhancement of gas separation performances of polyurethane–3A zeolite were found to be 18 wt%, 30 °C and 0.8 MPa respectively. Under these conditions, the permeabilities of carbon dioxide, methane, oxygen and nitrogen gases were measured at 138.4, 22.9, 15.7 and 6.4 Barrer respectively while the CO2/CH4, CO2/N2and O2/N2selectivities were 5.8, 22.5 and 2.5, respectively. Also, the optimal conditions for improvement of the gas separation performance of polyurethane–ZSM 5 were found to be 15.64 wt%, 30 °C and 4 bar. The permeabilities of these four gases (i.e.carbon dioxide, methane, oxygen and nitrogen) were 164.7, 21.2, 21.5 and 8.1 Barrer while the CO2/CH4, CO2/N2and O2/N2selectivities were 7.8, 20.6 and 2.7 respectively.

•Drying behavior of poultry litter was investigated.•Air temperature has the highest effect on crude protein and specific energy consumption.•Optimal specific energy consumption during the poultry litter drying was obtained.•Optimal crude protein and drying effectiveness during the drying of poultry litter was obtained.•Models were confirmed with experimental data to achieve the desired goals.

The development of thin film composite (TFC) membranes offers an opportunity to achieve the permeability/selectivity requirements for optimum CO2separation performance. However, the durability and performance of thin film gas separation membranes are mostly challenged by weak mechanical properties and high CO2plasticization. Here, we designed new polyurethane (PU) structures with bulky aromatic chain extenders that afford preferred mechanical properties for ultra-thin-film formation. An improvement of about 1500% in Young’s modulus and 600% in hardness was observed for pentiptycene-based PUs compared to the typical PU membranes. Single (CO2, H2, CH4, and N2) and mixed (CO2/N2and CO2/CH4) gas permeability tests were performed on the PU membranes. The resulting TFC membranes showed a high CO2permeance up to 1400 GPU (10–6cm3(STP) cm–2s–1cmHg–1) and the CO2/N2and CO2/H2selectivities of about 22 and 2.1, respectively. The enhanced mechanical properties of pentiptycene-based PUs result in high-performance thin membranes with the similar selectivity of the bulk polymer. The thin film membranes prepared from pentiptycene-based PUs also showed a twofold enhanced plasticization resistance compared to non-pentiptycene-containing PU membranes.

Thermal conductivity is an essential component in multiphysics models and coupled simulation of heat transfer, fluid flow, and solute transport in porous media. In the literature, various empirical, semiempirical, and physical models were developed for thermal conductivity and its estimation in partially saturated soils. Recently, Ghanbarian and Daigle (GD) proposed a theoretical model, using the percolation-based effective-medium approximation, whose parameters are physically meaningful. The original GD model implicitly formulates thermal conductivity ?as a function of volumetric water content ?. For the sake of computational efficiency in numerical calculations, in this study, we derive an explicit ?(?) form of the GD model. We also demonstrate that some well-known empirical models, e.g., Chung-Horton, widely applied in the HYDRUS model, as well as mixing models are special cases of the GD model under specific circumstances. Comparison with experiments indicates that the GD model can accurately estimate soil thermal conductivity. An explicit form of the Ghanbarian-Daigle physically based model for thermal conductivity in unsaturated soil is derivedIt is shown that the Chung-Horton model, widely used particularly in the HYDRUS model, is a special case of the Ghanbarian-Daigle modelWe recommend using the Ghanbarian-Daigle model for improved simulation of water and heat flow in the vadose zone

In this paper, the general form of the linear vibrational eigenvalue problems with some boundary conditions is considered. The given problem is then formulated by the operational Tau method with arbitrary polynomial bases. Afterward, considering the most common form of the vibrational eigenvalue problems and boundary conditions, some useful relations are derived from the method to solve such problems easily with a rapid rate of convergence. Finally, some numerical samples are solved with Chebyshev, Legendre and Standard basis and compared with the analytical solutions to clarify the efficiency and accuracy of the method in solving continuous vibrational problems.

In this study, we report highly selective CO 2 polyurethane incorporated with cured epoxy nanoparticles. PU–epoxy composite membranes were prepared via solution casting method. The obtained SEM micrographs confirmed the nano-scale distribution of epoxy particles in the polymer matrix. DSC and FTIR spectra showed different phase separation for the PU composites compared to the pure PU. The effect of epoxy nanoparticles on the gas permeability of CO 2 , CH 4 , O 2 and N 2 was studied at 25 °C and 10 bar. The selectivity of CO 2 /N 2 increased from 25 for the pure PU membrane to 55.5 for the PU–EP10, while the CO 2 permeability was unchanged. [ABSTRACT FROM AUTHOR]

The Miller‐Miller similar media theory is widely applied to characterize the spatial variability of soil hydraulic properties. For a group of soils, a distinct scaling factor is commonly assigned to each individual soil to coalesce the soil water characteristic and hydraulic conductivity functions to single curves. It is generally assumed that the Miller‐Miller theory is valid as long as soils are “similar” either with regard to their microscopic pore space geometry or the closely related macroscopic soil hydraulic functions. In this paper, it is illustrated that similarity is not the sole required condition for validity of the Miller‐Miller theory. In addition, the interrelation between the soil water characteristic and the hydraulic conductivity functions considered for scaling need to be comparable. The interrelation is dependent not only on the pore space geometry, but also on solid‐liquid interactions. Hence similar interrelation cannot be concluded from similarity of microscopic pore space geometry. A dimensionless parameter termed the “joint scaling factor” was defined and applied to evaluate the soundness of the interrelation condition for 26 soils from the UNSODA database that were grouped into six classes of similar soils. Obtained results clearly reveal the crucial importance of the interrelation condition for the Miller‐Miller scaling theory, which has been hidden behind the “similarity” requirement, and contradict the general belief that Miller‐Miller scaling is valid as long as soils are “similar.” Soil similarity is not sufficient for applicability of Miller‐Miller scalingThe interrelation between h(S) and K(S) functions also needs to be comparableBesides pore geometry, the interrelation depends on solid‐liquid interactions

AbstractIn this research, the capability of ultrafiltration hollow fiber polyvinylidene fluoride membrane by polyaluminum chloride in pretreated oil-in-water emulsion was studied. Central composite design and response surface method were applied to optimize the operating variables: transmembrane pressure (TMP) and velocity. Quadratic models developed for the three responses (permeate flux (PF), turbidity removal, and chemical oxygen demand (COD) removal) indicated that the optimum PF of 50 L/m2 h, turbidity removal of 79%, and COD removal of 77% would be achieved after pretreatment at a TMP of 1 bar and velocity of 3 m/s. The simulated values obtained from the statistical model were in agreement with the experimental results.

In this research, the capability of ultrafiltration hollow fiber polyvinylidene fluoride membrane by polyaluminum chloride in pretreated oil-in-water emulsion was studied. Central composite design and response surface method were applied to optimize the operating variables: transmembrane pressure (TMP) and velocity. Quadratic models developed for the three responses (permeate flux (PF), turbidity removal, and chemical oxygen demand (COD) removal) indicated that the optimum PF of 50 L/m2 h, turbidity removal of 79%, and COD removal of 77% would be achieved after pretreatment at a TMP of 1 bar and velocity of 3 m/s. The simulated values obtained from the statistical model were in agreement with the experimental results.

This paper presents a novel model for investigating squeeze film effect on a simple flexural beam resonator based on modal Galerkin reduced order method, step by step linearization and state space formulation. In contrast to conventional equivalent circuit model, this method enables the user to calculate scattering parameters of the filter as a two port network directly from geometry, consequently has the capability for considering any physical phenomena (in this case squeeze film effect) without losing generality. In this study a clamped-clamped beam has been considered as the resonating structure of the filter and the problem has been solved for dynamic motion of the beam simultaneously with gas pressure, voltages, and electrical current of input and output port of the filter. The results were verified with previous experimental and theoretical studies and an acceptable agreement achieved.

In this paper, the static behaviour of the Pride’s engine block under pressure and thermal loads in the course of combustion is analysed using the finite element method (FEM). For this purpose, the engine block with its full details including water-jackets, journal positions with oil slots and so on, is modelled and then the model is meshed. To ensure geometric modelling, the dynamic characteristics of the model were obtained by experimental modal analysis and the results compared with the ones obtained by the numerical (FEM) modal analysis. By imposing mechanical and thermal loads, stresses and strains were computed. The results were compared with the available experimental or theoretical-related works. The results show that thermal loads have the most significant effect on the cylinder block deformation. This deformation is higher in the lateral direction than the longitudinal one, and decreases from the top to the bottom of the cylinder block. In addition, the maximum stress is highest in cylinder no. 3. The results confirm the accuracy of the geometric modelling.

Topics such as passenger's safety, seat performance in the crashes, energy absorption by the seat, are the major concern in vehicle design. Automobile seat, as a member which is in direct interaction with the passenger, has a major rule in providing passenger's safety. Statistics show that rear-side collisions, which cause severe injuries, have the forth rank among other type of crashes. Moreover, three out of four injuries caused by such crashes, are neck injuries. Therefore, seat design has a major rule in reducing the severity of the neck injuries. In this study, the measurement of the energy index by using FEM based method has been introduced, and the technique to increase the energy absorption by the seat structure has been investigated, and the effect of design parameter-variation on the severity of injuries has been studied via the simulation of rear-side collision. In this article most important patents are also discussed.

Evaporation from soil and other porous media constitutes a significant source of water loss affecting global water balance and energy exchange between land and atmosphere. The presence of a shallow water table can lead to sustained water loss that is dependent on porous media hydraulic properties and water table depth among other factors. In this paper, an exact analytical solution to steady state evaporation from porous media is developed using the Brooks‐Corey hydraulic conductivity model. The solution is presented in terms of a set of infinite series. An advantage of this solution compared to previous derivations is that the infinite series can be very closely approximated using a closed‐form solution (i.e., excluding integrals or series). The novel solution shows excellent agreement with the exact solution for a broad range of soil texture from sand to clay. The applicability of the solution to predict the location of the drying front was also verified using experimental data taken from the literature. The solution may be used for directly modeling steady state evaporation or for inverse determination of the Brooks‐Corey hydraulic parameters. Improvement of the estimate of evaporation from soilA new analytical solution for water status above a water tableFitting of Brooks‐Corey hydraulic conductivity parameters

During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. A novel approach for reducing large standing phase angle (SPA) based on Genetic Algorithm (GA) is presented in this paper. The proposed approach starts with a state estimation on Wide Area Monitoring System (WAMS) data measurements and considering power system operation and angular stability constraints, seeks an optimal control action scenario for reducing SPA. Since these constraints are evaluated based on WAMS data, the presented approach is considerably high speed and accurate. As an optimization problem, objective function of the proposed approach is to minimize variation from the current state of the power system. Simulation results on the IEEE 118 bus test system clearly show efficiency of the approach.

During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. A novel approach for reducing large standing phase angle (SPA) based on Genetic Algorithm (GA) is presented in this paper. The proposed approach starts with a state estimation on Wide Area Monitoring System (WAMS) data measurements and considering power system operation and angular stability constraints, seeks an optimal control action scenario for reducing SPA. Since these constraints are evaluated based on WAMS data, the presented approach is considerably high speed and accurate. As an optimization problem, objective function of the proposed approach is to minimize variation from the current state of the power system. Simulation results on the IEEE 118 bus test system clearly show efficiency of the approach.