Search

With regard to an inherent understanding of electrical conductivity exhibited by monolithic metals and alloys system and metal matrix composite system under alternating current field, a long-standing unresolved issue, an analytical model is developed following classical free electron theory along with a typical conceptualisation of 'effective relaxation time' that combines conventional relaxation time (in view of collision of free electrons with lattice defects) and the time between successive cyclic reversals of electric field (the inverse of frequency). Two prime phenomena (electron scattering and polarisation at particle–matrix interface) are further conceived for metal matrix composite system containing particles. The developed model is found to closely follow (% deviation << 10) the available experimental result in the literature on A.C. electrical conductivity of 6063Al alloy and 6063Al–TiO2 composite systems. The model further ascertains certain system-specific parameters; such as, relaxation time under A.C. field, effective scattering factor and effective relaxation time aid from interface polarisation to specify the system behaviour under alternating current field. Accordingly, the model adequately explains the declining trend of A.C. electrical conductivity with increasing frequency in monolithic alloy system and an enhancement of A.C. electrical conductivity in metal matrix composite system in the presence of particles together with a non-declining trend even on increasing frequency. [ABSTRACT FROM AUTHOR]

Laser shock forming (LSF) is a novel plastic forming process which utilizes a laser-induced shock wave to deform metal sheet to 3D configurations. Quantitative evaluation of the deformation in LSF is of great importance to understand the forming mechanism and achieve the high precision. In this paper, an analytical model was proposed to predict the deformation of a circular plate in laser shock bulging process. Models showed that the deformation is related to material parameters such as the impedance, density, yield strength of the metal target, geometric parameters such as the plate thickness and die radius, and processing parameters such as the energy, radius and pulse duration of the laser beam. The deformation profiles and the maximum deformation height calculated by the analytical model agree with those of experiment, which validate the rationality of the constructed models. The maximum deformation height increases with an increase of laser energy and decreases with increasing plate thickness. [ABSTRACT FROM AUTHOR]

Highlights To predict the coefficient of thermal expansion (CTE) of carbon fiber/epoxy resin composites with void defects comprehensively and accurately, a comprehensive study is carried out by integrating experiment, analytical model (ANM), and finite element model (FEM). The experiments on composites are conducted combining with Micro‐CT to provide geometric parameters and verification for ANM and FEM. An ANM considering void defects is established based on the Chamis model to investigate the influence of porosity, temperature and the ratio of modulus of the constituents of composites. A FEM is established to verify the ANM and reveal the mechanisms of the influence of void defects. The results show that the proposed ANM has high agreement with FEM and experiment. The longitudinal CTE decreases by 61.94% as the porosity increases from 0% to 20% at 60°C, and the same change of porosity results in a 15.62% decrease at 180°C. The transverse CTE is less susceptible to changes in porosity, showing reductions of 2.32% at 60°C and 3.33% at 180°C. An innovative model is proposed to predict CTE considering void defects. The glass transition temperature Tg of the resin has a significant effect on CTE. Void defects change the homogeneity of the original stress field of the matrix. The reduction of the longitudinal CTE caused by void defects is more significant. [ABSTRACT FROM AUTHOR]

We theoretically analyzed the rotational behavior of beam–column dovetail joints in traditional Chinese timber frames in this study. An analytical model of dovetail joints at both the column head and body was designed by clarifying the moment generation mechanism and effect of rotational embedment yielding in timber perpendicular to the grain on the rotational behavior of joints. An asynchronous manifestation of rotational embedment deformation across the column surface, tenon cheeks, and upper and lower surfaces of the tenon head was analyzed, and the corresponding characteristic yield points and consequent reduction in rotational stiffness were derived in the model. The Inayama embedment theory was used to clarify the effect of rotational embedment with varying end lengths on the movement of the joint rotation center and asymmetric moment generated in different rotation directions of the column head joint. The precision of the analytical model was validated through a comparative analysis by involving nine sets of experimental data, for estimating the initial stiffness, post-yield stiffness, and identified yield points. The implications of the parameters, including the initial gap between the tenon and mortise, geometric dimensions of the dovetail tenon, and friction coefficient, were also discussed. Controlling the ratio of the initial gap and tenon height within 0.01 to ensure a certain rotational resistance of dovetail beam–column joints within the collapse limits of traditional timber frames is recommended considering the significant effect of the initial gap on the initial sliding angle and moment reduction. [ABSTRACT FROM AUTHOR]

AbstractThe ceramic core sandwich structure (CCSS) is a lightweight material with advantages of high anti-ballistic impact performance, high energy absorption and high specific strength. The ballistic performances of the CCSS with metal face plates hit vertically by projectiles with the nose shapes of conical, flat, and hemispherical are studied analytically and numerically in this paper. Based on the principle of energy conservation, an analytical model of ballistic characteristics of the sandwich ceramic core structure is developed. Numerical calculations are conducted, and the numerical model has been verified by experimental results from references by others. In addition, the analytical results agree well with finite element results. The effects of shape of projectile head, the thickness ratio of three plates of CCSS, and the ratio of shear strength of ceramic core to yield strength of metal face plates on the ballistic characteristics of the CCSS are discussed. It is shown that the conical-nosed projectile achieved the highest ballistic limit velocity (BLV) and the sharper nose increases the normal stress at the impact area thereby enhancing the BLV. The thickness of the ceramic core significantly influences the resistance of the CCSS and the thicker ceramic core enhances the ability of CCSS to absorb kinetic energy from the projectile. Furthermore, an appropriate increase in the yield strength of face plates can enhance the anti-ballistic impact performance of the CCSS. These insights have practical implications for the design of protective systems in military and civilian applications, where optimizing materials for impact resistance is crucial. [ABSTRACT FROM AUTHOR]

As a typical passive energy dissipation device, the fluid viscous damper (FVD) is widely utilized for structural vibration control. However, performance degradation in FVDs has been highlighted, particularly concerning the gap effect resulting from the imperfect installation and insufficient fluid. This study proposes three analytical models to characterize the gap property in the hysteresis behavior of FVDs, including the Gap model (G. model), the Equivalence model (E. model), and the Stiffness Degradation model (S. model). The purpose of the G. model is to reproduce the zero-force platform in the hysteresis curve. The E. model and S. model are both simplified models, aiming to consider the gap effect by altering the damping coefficient, velocity exponent, and stiffness based on the energy and maximum force equivalence principles. Shake table tests of a single-degree-of-freedom system are carried out to validate and assess the effectiveness and accuracy of these three methods. The results indicate that the gap effect will significantly degrade the vibration mitigation performance of FVDs, and hence it needs to be considered in simulations. The displacement and force obtained using the G. model under distinct loads highly correspond to the experimental results. By adopting the simplified models, satisfactory results can be derived with a lower implementation cost. Among them, the E. model is more appropriate when subjected to harmonic loads, while the S. model is suggested for cases under seismic excitations. [ABSTRACT FROM AUTHOR]

Accurate magnetic field calculation is the premise of electromagnetic performance prediction. Conventional subdomain (SD) techniques assume that the iron's relative permeability is infinite, leading to falsely overestimated flux density. We propose an accurate magnetic field analytical model for permanent magnet (PM) in-wheel machines considering iron's magnetization nonlinearity and saturation. Specifically, according to the excitation source and topology, the entire solution domain of the machine is divided into sub-regions such as stator slots/teeth, stator slot-openings/tooth-tips, air-gap, and rotor slots/teeth, etc. Poisson's or Laplace's magnetic vector potential (MVP) equations are solved using Maxwell's electromagnetic theory and complex Fourier series methods in each sub-region. Specifically, in our approach, The Cauchy product theorem addresses the discontinuous magnetic permeability change at the slot and tooth interface. The machine's magnetic saturation effect is considered by combining the actual magnetization characteristics of iron with an iterative algorithm. The general solution for the MVP is solved using the boundary conditions between adjacent subregions. Subsequently, electromagnetic properties such as air-gap flux density, back electromotive force (EMF), and electromagnetic torque are obtained. The accuracy of the analytical model is verified by finite element analysis (FEA) and prototype tests, which proved that the proposed analytical model can consider the iron's nonlinearity and the magnetic saturation. In addition, the inaccurate overestimation of electromagnetic torque and air-gap magnetic flux density by the conventional SD techniques has also been proven. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to determine more robust shear failure criteria, focusing on rough concrete-rock interfaces. The proposed method could also be applied to rock joints. The new approach is based on the distribution and variety of interfaces numerically tested in terms of surface roughness. For this reason, random field simulations are performed using the turning bands method to generate an extensive database of synthetic rough rock surfaces. With this database of synthetic rough rock surfaces, numerical simulations of direct shear tests are carried out. Finally, analytical and neural network models are proposed using the database of shear strength obtained from the finite element simulations to estimate the peak shear strength of concrete-rock interfaces. The performances of the analytical and neural network models in estimating this peak shear strength are evaluated by computing the percentage error and the mean absolute error (MAE) between the predicted and the numerically obtained values. Both models lead to satisfactory predictions. Nevertheless, it is worth noting that the neural network model mildly outperforms the analytical model regarding the magnitude of the error. Furthermore, the neural network model reproduces the possible non-bijective aspect of the correlation roughness-peak shear strength. Highlights: New methodology to investigate the influence of roughness on the shear behavior of interfaces Methodology to generate databases of synthetic rough rock surfaces with controlled roughness values Establishment of numerical simulations as a strategy to perform extensive virtual experimental studies The correlation between interface roughness and shear strength is not bijective. Assessment of artificial neural network modeling as a complementary alternative to failure criteria [ABSTRACT FROM AUTHOR]

Efficient and accurate calculation of stress overload and stress redistribution near the fiber breakpoint is the basis for simulating the tensile damage evolution of unidirectional fiber reinforced plastic (FRP), and it is also the premise for predicting the tensile-tensile fatigue life. In this study, an efficient finite element (FE) model with a large number of fibers was developed based on the FE method to calculate stress concentration factor (SCF) near multiple breakpoints, and the calculation time only takes 3 min on average. The FE model is used to efficiently calculate multiple breakpoints and the stress distribution near the breakpoint considering the interface debonding. Based on the efficient FE model, an analytical model is developed to calculate the stress overload superposition around multiple breakpoints. In this analytical model, the shear stress distribution near the broken fiber elements is established based on the experiment, and the stress redistribution mechanism near the breakpoint in FRP with random distribution of fibers is established. Moreover, the calculation method of stress overload near multiple break points is established, and the FE method is verified. [ABSTRACT FROM AUTHOR]

An analytical method and numerical simulation were developed to investigate the shear performance of fiberglass rock bolts (20-tonne and 30-tonne) by conducting sixteen double-shearing tests with both clean and infilled shear interfaces. Following the preparation of the required samples, each test set-up was subjected to different ranges of pretension values. The infilled scenario involved 5 mm thick sandy clay infilled shear interfaces. The results of the double shearing tests unveiled that as pretension increased, so did the confining pressures at the shear interfaces for both clean and infilled joints. Also, an analytical model was developed utilising the Fourier transform, energy balance theory, and linear elastic theory. The result was an empirical relationship that could determine the double shear performance of fibreglass rock bolts in close agreement with the experimental data. Coefficients were incorporated to facilitate model calibration and tuning. Eventually, fast Lagrangian analysis of continua (FLAC) three-dimensional (3D) modelling was utilised to conduct numerical simulations of fibreglass rock bolts subjected to double shearing scenarios. The numerical model was calibrated against experimental data and then extended to conduct a sensitivity analysis on fibreglass rock bolts subjected to double shear test setup variations. Scenarios included rock bolt installation angles, shearing rates, and various host rock strengths. The results revealed that increasing the shear speed from the experimental test baseline yielded substantial displacement increases in the post-failure residual performance of the rock bolts. Changing the installation angle resulted in greater peak shear forces and extended residual zones. The least significant impacts were observed when changing the host rock UCS, suggesting neither rock bolt was drastically impacted by weak or strong host rocks. [ABSTRACT FROM AUTHOR]

Due to complex geological structures and potential environmental impacts, single-well production in coal-measure gas reservoirs is not satisfactory. Field studies have shown that co-production is a promising approach, which can efficiently and economically extract multiple gas resources. However, the literature lacks a mathematical model to accurately describe and predict the production behavior during co-production. Based on the five-linear flow model, this work presents an analytical solution to evaluate the production dynamics characteristics of co-production between coalbed methane and tight gas reservoirs. In addition, the proposed model accounts for factors such as dual-porosity media, the gas slippage effect, and the matrix shrinkage effect. With the aid of the model, sensitivity analyses of the Blasingame decline curve and the layered flux contribution are conducted. The calculation results show that a higher fracture conductivity, as well as a longer fracture length, lead to larger cumulative production. Additionally, increased layer thickness significantly boosts flux contribution throughout the production period. Finally, large boundary distances extend the duration of high flux contributions in late production. This research contributes to a better understanding of the production dynamics in coal-measure gas reservoirs and offers practical guidelines for reservoir management in co-production scenarios. [ABSTRACT FROM AUTHOR]

This article presents an analytical model for the diurnal cycle of slope‐normal profiles of potential temperature and wind speed characterizing thermally driven slope winds, generated by a daily‐periodic surface energy budget. The model extends the solution proposed by Zardi and Serafin, originally formulated for a pure sinusoidal surface forcing temperature. To account for the asymmetric features characterizing the daytime and nighttime phases, a full Fourier series expansion is derived, the coefficients and phases of which are prescribed from the surface energy budget driven by the daily‐periodic radiation model described in Part 1 of the present work. The model is applicable for any slope angle (0∘≤α≤90∘$$ {0}^{\circ}\le \alpha \le {90}^{\circ } $$) and orientation, at any latitude and elevation (up to 2500 m), and for all seasons. Despite some inherent limitations, the most remarkable being the absence of moist processes and latent heat fluxes, the model captures most key features of daily‐periodic slope wind systems, in particular the asymmetry between daytime and nighttime phases. Moreover, it allows exploration of the sensitivity of these flows to the various factors concurring in their development, and offers a basis for more realistic analytical solutions for slope winds. [ABSTRACT FROM AUTHOR]

Flow of suspensions through the complex porous network is typically characterized by the initial spurt and then the formation of internal/ external filter cake which impedes the flow velocity. The transient mechanisms involved during the particle migration phenomenon need to be studied carefully as it is crucial for effectively managing the flow characteristics of drilling fluids and their impact on subsurface reservoirs. In this study, constant pressure permeation experiments are carried out using a specially designed apparatus to quantify the formation and evolution of particle migration zones using advanced image processing algorithms. Additionally, a comprehensive pre-test and post-test characterization of drilling fluids/ filtrates and the porous medium revealed intricate insights into the dynamics of particle migration. Four distinct particle migration/ filtration zones such as internal filter cake, primary filtration, secondary filtration and fluid loss are identified based on the change in the concentration gradient. The influence of additives on the growth of these zones is quantified during the filtration process. The concentration of barite/ micronized calcium carbonate and xanthan gum predominantly controls the filtration process by enhancing the particle plugging and retention time, respectively. In addition to the in-depth understanding of the particle migration zones, the transition from kinetic to capillary flow is identified by performing the fractal analysis. The analysis revealed that drilling fluid containing more barite exhibits a dominant capillary flow. Finally, an analytical model has been modified by considering the influence of different additives to predict the depth of penetration, which is comparable with the experimental results. [ABSTRACT FROM AUTHOR]

Repair of reinforced concrete structures is required to preserve the adequate performance of these structures throughout their service life. One of the credible techniques is using fibrous concrete as a repair material. In this paper, the performance of steel fibre-reinforced geopolymer concrete (SFRGPC) in the repair of pre-damaged reinforced concrete T-beams (pre-loaded up to 50% of their shear capacity) failing in shear was investigated. Five T-beam series and a four-point loading test were adopted: one reference beam, three beams were repaired with different fibrous ratios of 1, 2, and 3%, and one was repaired with 2% steel fibre and additional U-steel stirrups. The key test results include crack propagation, crack width, initial stiffness, load deflection, peak loads, and strain associated with web stirrups. A clear enhancement was noticed in the performance of the repaired T-beams; their shear capacity was boosted by as much as 45% compared to the control beam. It was also deduced that the beam went from a brittle to a ductile failure mode at 3% SFRGPC and at 2% SFRGPC with U-stirrups. Finally, an analytical model prediction was proposed to predict the shear capacity of repaired T-beams with the SFRGPC. The model showed a satisfactory correlation with experimental results, with an average ratio of 0.995 and a standard deviation of 0.035. [ABSTRACT FROM AUTHOR]

Eccentrically Braced Frames (EBFs) equipped with steel shear links primarily sustain large deformation demands through inelastic actions in the links, including yielding, bucking, and fracture of the steel plates or weld parts. This failure mode becomes more complex and results in highly nonlinear behavior using Low-Yield-Point (LYP) steels for the construction of the links due to their high strain hardening capacities. The existing analytical models have been presented for links made of normal steel grades, and thus there is a substantial research need for developing an analytical model to capture the actual behavior of links made of LYP steels. To fill this gap, this paper developed both shear-hinge and shear-spring-based models for performance-based evaluation of EBFs equipped with LYP steel shear links, which are more practical models in general-purpose structural analysis programs. The accuracy of the proposed model was assessed by comparing it with existing experimental tests and analytical models. As a result, there is good agreement between the proposed model and test results in terms of initial stiffness, post-yielding stiffness, and strength, which shows significant improvement over existing analytical models. [ABSTRACT FROM AUTHOR]

• An analytical model is proposed for the semi-parallel stay cables under axial tensile loads. • The friction generated by adjacent steel wires under contact force and relative slip is considered. • The angle between the principal torsion-flexure axes and Frenet–seret axes of each wire is yielded. • The effect of friction on stay cable is clarified according to mechanical performance along axial direction of the wire. A novel analytical model is proposed to evaluate the influence of adjacent wire friction on the mechanical properties of semi-parallel stay cables. This model considers the bending and torsional stiffness of semi-parallel wires and the friction between adjacent contact wires. The finite difference method and nonlinear least squares method are used to solve the angle between the principal torsion-flexure axes and Frenet–Serret axes of the wires numerically, and each wire is solved sequentially according to the equation of the force transmission. The helical radius and angle of all wires after deformation are derived according to the angle, and the problem is iteratively solved until convergence of all wires. The effectiveness of the proposed model is verified via the refined finite element model of a 19-wire stay cable. The proposed method accurately evaluated the mechanical properties of adjacent wire friction on stay cable by analyzing the influence of angle on the semi-parallel wires, which is more conducive to understanding the fretting wear and fatigue behavior of wires and quantifying their damage. [ABSTRACT FROM AUTHOR]

Structural strengthening solutions typically employ externally bonded reinforcement (EBR) systems with carbon fiber (CF) sheets because of these materials' lightweight, corrosion resistance, and electromagnetic immunity. However, elevated ambient temperatures can negatively impact the mechanical performance of EBR, as documented in the literature. Therefore, American bridge design specifications assume a concrete surface temperature of 60 °C (140 °F), which reflects the extreme conditions that bridge structures may experience, particularly in regions with intense sunlight and high ambient temperatures. Therefore, sustainable design solutions require a reliable quantification of the effects of temperature. This study extends a recently developed bending test layout and builds the analytical modeling procedure to quantify the stiffness degradation under repeated temperature and mechanical loads. The explicitly obtained equivalent stresses in the tensile concrete determine the stiffness measure independent of the loading condition and sequence. This test program used 12 laboratory samples. All beam samples faced the mechanical load repetitions and entire unloading. Three selected beams were additionally treated at 60 °C for 10 hours in a heating chamber between the loading repetitions. These tests identified a substantial (three times) decrease in the bonding performance of the CF sheets after eight heating rounds. Scanning electron microscopy (SEM) identified the corresponding microstructure changes. • This work proposes an efficient measure to quantify flexural stiffness. • It is suitable for repeated combinations of temperature and mechanical loads. • The wet-layup CF EBR system tends to lose its reinforcement performance at 60 °C. • This effect appears after three mechanical load and heating repetitions. • The epoxy bond deterioration can explain the reinforcement efficiency decrease. [ABSTRACT FROM AUTHOR]

The chip compression ratio is the most important characteristic of various machining processes with chip generation. This characteristic enables the determination of kinetic and other energy loads on the tool and the machined material. This provides an overall evaluation of the machining process and the possibility of its subsequent optimization. This paper presents the results of determining this cutting characteristic by experimental method, analytical calculation, and numerical modeling. For the analytical calculation of the chip compression ratio, an analytical cutting model developed based on the variational principle of the minimum potential energy was used. A finite element model of orthogonal cutting was used for the numerical simulation of the above process characteristic. Experimentally, the chip compression ratio was determined by the ratio of the chip thickness to the cutting depth (undeformed cutting thickness). The chip thickness was determined by direct measurement using chip slices obtained during the cutting process. The Johnson–Cook constitutive equation was used as the machined material model and the Coulomb model was used as the friction model. The generalized parameters' determination of the constitutive equation was performed through a DOE (Design of Experiment) sensitivity analysis. The variation range of these parameters was chosen based on the analysis of the effect of individual parameters of the constitutive equation on the chip compression ratio value. The largest deviations between the experimental and analytically calculated values of the chip compression ratio did not exceed 21%. At the same time, the largest deviations of simulated values of the indicated cutting characteristic and its experimental values did not exceed 20%. When comparing the experimental values of the chip compression ratio with the corresponding calculated and simulated values, the deviations were within 22%. [ABSTRACT FROM AUTHOR]

New developments in nickel-based superalloys and production methods, such as the use of additive manufacturing (AM), can result in innovative designs for turbines. It is crucial to understand how the material behaves during the AM process to advance the industrial use of these techniques. An analytical model based on reaction–diffusion formalism is developed to better explain the solidification behavior of the material during laser metal deposition (LMD). The well-known Scheil–Gulliver theory has some drawbacks, such as the assumption of equilibrium at the solid–liquid interface, which is addressed by this method. The solidified fractions under the Scheil model and the pure equilibrium model are calculated using CALPHAD simulations. A differential scanning calorimeter is used to measure the heat flow during the solid–liquid phase transformation, the result of which is further converted to solidified fractions. The analytical model is compared with all the other models for validation. [ABSTRACT FROM AUTHOR]

In this article, a three‐dimensional (3D) auxetic system is designed by linking layers of rotating squares with torsion springs. The orientation of the rotating squares in the different layers is organized in such a way that when a tensile load is applied on them, corresponding squares would rotate in opposite directions. This creates a torque that acts on the torsion spring. As a consequence, the length of the torsion spring increases resulting in a negative Poisson's ratio in three dimensions. An analytical model for the Poisson's ratio is derived and then tested using a 3D‐printed specimen of the proposed design. The results are found to be in general good agreement. [ABSTRACT FROM AUTHOR]

The milling process has proven to be a versatile process for the manufacturing of complex components at the macro- and micro-scales. Development of the cutting force prediction model in milling is important for process planning and optimization, as well as the controlling of machining accuracy. The well-established milling force prediction models include analytical, empirical, and numerical models, among which the analytical models are the most useful for characterizing the milling process and enhancing the understanding of the mechanics of the milling process. This paper makes a detailed review on the analytical models for the force predictions in macro- and micro-milling processes by analyzing the calculation modeling of the instantaneous uncut chip thickness (IUCT) and the determination methods of milling force coefficients. The development of the IUCT model starts from the studying of the effects of circular and trochoidal tool tip locus, later tool and workpiece deflections, tool runout, and tool wear, then the effects of cutting tool edge radius and workpiece material properties in the micro-milling process. The methods for cutting force coefficients are summarized and divided into three subgroups: the first is in constant form and obtained from the experiment, the second is expressed as the functions of the depth of cut, while the third is represented as the polynomial form under different influencing factors including machining conditions, tool geometries, and IUCT effect. The modeling laws and the key challenges for milling forces are also discussed for future research. [ABSTRACT FROM AUTHOR]

The railway is an essential source of logistics and transportation in cold regions, but low temperatures and icing can be challenging for uninterrupted railway operations in these regions. Icing on railway switches is a safety hazard, and presently, one of the industry's adaptive approaches for ice mitigation is the use of resistive heaters. This method is efficient but consumes a great amount of electricity, leading to high financial costs in terms of the operation and maintenance of railway tracks in ice-prone regions. In this paper, a study is carried out using experiments and computational simulations to analyze the heat distribution in a cross-section of a rail at below-freezing temperatures. Experiments are performed in a cold room using an actual rail switch, thermocouples, and infrared imaging, while numerical analyses are carried out using a MATLAB-based analytical model to simulate the heat transfer, considering a section of stock rail and a heating element. Results show a considerable loss of heat from the heater to the surroundings of the rail, especially towards the ground ballast. Numerical simulation results provide a good insight into heat transfer along railway sections, and results are validated with experiments, where a good agreement is found. This study provides a good base for further optimization of resistive heating operations for ice mitigation along railway switches. [ABSTRACT FROM AUTHOR]

Crystalline matters with periodically arranged atoms found wide applications in modern science and technology. To facilitate the design of new materials and the advancement of existing ones, accurate and efficient models without relying too much on known inputs for predicting the functionalities are essential. Here, we propose an analytical approach for such a purpose, with only the knowledge of the structural chemistry of crystals. Based on the electrostatic interaction between periodically arranged atoms, the 1st, 2nd and 3rd derivatives of interatomic potential, respectively, enable a prediction of ten kinds in total of mechanical, acoustical and thermal properties. Over a thousand measurements are collected from ∼500 literatures, this results in the symmetric mean percentage error (SMPE) within ±25% and the symmetric mean absolute percentage error (SMAPE) ranging from 22%∼74% across all properties predicted, which further enables a revelation of bond characteristics as the most important but implicit origin for functionalities. [ABSTRACT FROM AUTHOR]

The problem of investigating the nonlinear acoustic waves in stepped acoustic resonators is treated theoretically. A perturbation scheme that combines the method of multi-scale expansion yields a set of coupled nonlinear ordinary differential equations for deriving an analytical model to describe the resonant oscillations. The nonlinear sound pressure in stepped resonator is predicted with accuracy up to the second-order terms of a small-amplitude parameter . The pressure amplitudes and waveforms at the closed end of stepped resonators with different size parameters are investigated by the derived analytical model and qualitatively compared with the measured results in experiment. The qualitative comparison of calculated and measured results shows good agreement. The results suggest that the sound pressure generated in stepped resonators with different size parameters may be very different. Not all stepped resonators can generate high-amplitude and low-distortion standing waves. The derived analytical model can be used to qualitatively study the nonlinear acoustic waves in stepped acoustic resonators and design suitable tube dimensions for resonant macrosonic synthesis. [ABSTRACT FROM AUTHOR]

The success of CO2 storage projects largely depends on addressing formation damage, such as salt precipitation, hydrate formation, and fines migration. While analytical models for reservoir behaviour during CO2 storage in aquifers and depleted gas fields are widely available, models addressing formation damage and injectivity decline are scarce. This work aims to develop an analytical model for CO2 injection in a layer-cake reservoir, considering permeability damage. We extend Dietz's model for gravity-dominant flows by incorporating an abrupt permeability decrease upon the gas-water interface arrival in each layer. The exact Buckley-Leverett solution of the averaged quasi-2D (x, z) problem provides explicit formulae for sweep efficiency, well impedance, and skin factor of the injection well. Our findings reveal that despite the induced permeability decline and subsequent well impedance increase, reservoir sweep efficiency improves, enhancing storage capacity by involving a larger rock volume in CO2 sequestration. The formation damage factor d, representing the ratio between damaged and initial permeabilities, varies from 0.016 in highly damaged rock to 1 in undamaged rock, resulting in a sweep efficiency enhancement from 1–3% to 50–53%. The developed analytical model was applied to predict CO2 injection into a depleted gas field. [ABSTRACT FROM AUTHOR]

To improve shear capacity, as well as reduce on-site casting and steel consumption, a novel Y-shaped perfobond rib (Y-PBL) shear connector with ultra-high-performance concrete (UHPC) grout was proposed. The shear behavior of the Y-PBL shear connector was investigated by six groups of pushout specimens. Their failure modes, load–slip curves, load–separation curves, strain analysis, and shear transfer mechanisms were discussed. Subsequently, finite-element analysis (FEA) models were established to study the effect of parameters on the shear behavior of the Y-PBL shear connector, as well as to compare the shear capacity contributions with straight-shaped PBL (S-PBL) shear connectors. Analytical models were proposed to predict the shear capacity of the Y-PBL shear connector. The results reveal that the proposed Y-PBL shear connector has superior shear capacity and stiffness. The contribution of the perforating rebar is minor compared with the end-bearing effect of UHPC. The analytical predictions agree well with the experimental and FEA results. This study can be used to guide the design and application of the Y-PBL shear connector in steel-concrete composite bridges. [ABSTRACT FROM AUTHOR]

Understanding the ecological conditions of vegetation growth in water sources is vital to appraise the influence of vegetation on river engineering. Based on the experimental information that is accessible, the consequences of vegetation on flow resistance is described as an alteration in the drag coefficient and the planned area. The current study analytically estimates the vertical distribution of stream-wise velocity in open-channel flow while considering rigid and flexible vegetation. The flow is vertically separated into top free water layer and bottom vegetation layer using the projected deflection height of both vegetation. Related momentum calculations for each layer are then derived. Based on the gathered experimental data, a 3D numerical model with various simulation situations is used to model, calibrate, and evaluate the artificial cylinders. A considerable deflection analysis is utilised to calculate the velocity-dependent stem height. This has proven to be more precise compared to formerly deflection investigation. The estimated outcomes show that precise predictions may be made for the vertical contours of vertical Reynolds shear stress based on mean horizontal velocity. The numerical simulations demonstrate that plant flexibility reduces the vertical Reynolds shear stress and prompted flow resistance force of the vegetation. [ABSTRACT FROM AUTHOR]

Recognizing the lightweight nature and superior tribological properties of Al-based metal matrix composites, this study introduces a novel analytical model based on polynomial approximations, offering new insights into the mechanisms of dry friction in AlSi10Mg-SiC composite materials. Key findings highlight a significant reduction in the coefficient of friction (COF) and oscillation amplitudes in SiC-reinforced composites, indicating superior tribological performance compared to their unreinforced counterparts. This behavior is attributed to the effective distribution of SiC particles within the aluminum matrix, which mitigates the stick–slip motion commonly observed under dry sliding conditions. Importantly, the model using polynomial approximations is noted for its simplicity and ease of implementation in practice. The study's conclusions not only underscore the benefits of SiC reinforcement in enhancing wear resistance but also contribute to the broader field of materials science by providing a robust framework for the predictive modeling of COF in various composite systems. [ABSTRACT FROM AUTHOR]

The eradication of diseases through vaccination has been a long-standing problem in developing countries. The supply chain plays an essential role in end-to-end connection and enhancing the effectiveness of successful immunization. However, no study highlights the vaccine supply chain's role in maximizing stakeholder outreach and a successful vaccination campaign. The supply chain cannot be applied as a 'one size fits all,' 'centralized,' or a 'black box approach' to every vaccination area, as each may require specific inputs from the supply chain. This study considers the Poliovirus eradication program at immunization centres in several vaccination areas in Pakistan and proposes tailored supply chain strategies that are conducive to the requirements of vaccination areas. There are four-fold contributions of this study, i.e., identification of several factors from the literature that can trigger various responses from the supply chain, prioritization of these factors using a graph theory approach, grouping of vaccination areas based on the similarity of factors for the formulation of supply chain strategies, and proposing three tiers of the customer-facing arc of integration for the vaccination areas. The first tier of integration strategies comprises accurate demand forecasts, controlling wastage, and enhancing synchronization among vaccination and other health services. The second tier of integration strategies comprises a mix of centralization and de-centralization, coordination, and robust information systems, considering the relocation of vaccination centres to population epicentres. The third tier of integration strategies comprises increased investment in awareness programs, increasing partnerships with private partners, and ensuring the well-being of personnel and ground support staff. Finally, the conclusion, limitations, and future recommendations are provided. [ABSTRACT FROM AUTHOR]

A new approach to predicting the geometrical characteristics of the mixing behavior of an inclined dense jet for angles ranging from 15° to 85° is proposed in this study. This approach is called the group method of data handling (GMDH) and is based on the artificial neural network (ANN) technique. The proposed model was trained and tested using existing experimental data reported in the literature. The model was then evaluated using statistical indices, as well as being compared with analytical models from previous studies. The results of the coefficient of determination (R2) indicate the high accuracy of the proposed model, with values of 0.9719 and 0.9513 for training and testing for the dimensionless distance from the nozzle to the return point x r / D and 0.9454 and 0.9565 for training and testing for the dimensionless terminal rise height y t / D . Moreover, four previous analytical models were used to evaluate the GMDH model. The results showed the superiority of the proposed model in predicting the geometrical characteristics of the inclined dense jet for all tested angles. Finally, the standard error of the estimate (SEE) was applied to demonstrate which model performed the best in terms of approaching the actual data. The results illustrate that all fitting lines of the GMDH model performed very well for all geometrical parameter predictions and it was the best model, with an approximately 10% error, which was the lowest error value among the models. Therefore, this study confirms that the GMDH model can be used to predict the geometrical properties of the inclined negatively buoyant jet with high performance and accuracy. [ABSTRACT FROM AUTHOR]

A 3D analytical model is formulated based on linearised small-amplitude wave theory to analyse the behaviour of a horizontal, flexible membrane subject to wave–current interaction. The membrane is connected to spring moorings for stability. Green's function approach is used to obtain the dispersion relation and is utilised in the solution by applying the velocity decomposition method. On the other hand, a brief description of the experiment is presented. The accuracy level of the analytical results is checked by comparing the results of reflection and the transmission coefficients against experimental data sets. Several numerical results on the displacements of the membrane and the vertical forces are studied thoroughly to examine the impact of current loads, spring stiffness, membrane tension, modes of oscillations, and water depths. It is observed that as the value of the current speed (CS) rises, the deflection also increases, whereas it declines in deeper water. On the other hand, the spring stiffness has minimal effect on the vibrations of the flexible membrane. When vertical force is considered, higher oscillation modes increase the vertical loads on the membrane, and for a mid-range wavelength, the vertical wave loads on the membrane grow as the CS increases. Further, the influence of the phase and group velocities are presented. The influences of CS and comparisons between them in terms of water depth are presented and analysed. This analysis will inform the design of membrane-based wave energy converters and breakwaters by clarifying how current loads affect the dynamics of floating membranes at various water depths. [ABSTRACT FROM AUTHOR]

This study presents the Flexible Rocking Model on Concentrated Springs (FRMCS), developed to investigate 2D laterally flexible oscillators rocking and sliding on deformable support media during ground excitations. In this model, concentrated vertical springs and viscous dampers simulate the contact forces from support medium at the corners of the body; the tensionless vertical contact element is linear in compression. Horizontal concentrated springs and linear viscous dampers simulate the frictional behaviour at the corners; the constitutive law for the springs models elastic deformations and sliding (according to Coulomb's friction law). With these elements, FRMCS can model the response of a rocking body which can experience sliding and free‐flight phases of motion. The consideration of the flexibility of the support medium enables the evaluation of the forces exerted by the support medium on the structure during an impact. In this study, the FRMCS response is first compared to a previous model where the support medium deformability and the effects of sliding and free‐flight are ignored. Then, the responses of four configurations, which feature either stiff or soft lateral springs and stiff or soft high‐grip support media, are examined under the influence of pulse excitations. Finally, to understand the potential influence of sliding, a configuration with a low‐grip support medium is explored. The comparative influence of lateral flexibility and support medium deformability and sliding is quantified with stability diagrams and various response spectra, describing structural force and moment demands. [ABSTRACT FROM AUTHOR]

Abstract We theoretically analyzed the rotational behavior of beam–column dovetail joints in traditional Chinese timber frames in this study. An analytical model of dovetail joints at both the column head and body was designed by clarifying the moment generation mechanism and effect of rotational embedment yielding in timber perpendicular to the grain on the rotational behavior of joints. An asynchronous manifestation of rotational embedment deformation across the column surface, tenon cheeks, and upper and lower surfaces of the tenon head was analyzed, and the corresponding characteristic yield points and consequent reduction in rotational stiffness were derived in the model. The Inayama embedment theory was used to clarify the effect of rotational embedment with varying end lengths on the movement of the joint rotation center and asymmetric moment generated in different rotation directions of the column head joint. The precision of the analytical model was validated through a comparative analysis by involving nine sets of experimental data, for estimating the initial stiffness, post-yield stiffness, and identified yield points. The implications of the parameters, including the initial gap between the tenon and mortise, geometric dimensions of the dovetail tenon, and friction coefficient, were also discussed. Controlling the ratio of the initial gap and tenon height within 0.01 to ensure a certain rotational resistance of dovetail beam–column joints within the collapse limits of traditional timber frames is recommended considering the significant effect of the initial gap on the initial sliding angle and moment reduction.

Abstract Accurate magnetic field calculation is the premise of electromagnetic performance prediction. Conventional subdomain (SD) techniques assume that the iron’s relative permeability is infinite, leading to falsely overestimated flux density. We propose an accurate magnetic field analytical model for permanent magnet (PM) in-wheel machines considering iron’s magnetization nonlinearity and saturation. Specifically, according to the excitation source and topology, the entire solution domain of the machine is divided into sub-regions such as stator slots/teeth, stator slot-openings/tooth-tips, air-gap, and rotor slots/teeth, etc. Poisson’s or Laplace’s magnetic vector potential (MVP) equations are solved using Maxwell’s electromagnetic theory and complex Fourier series methods in each sub-region. Specifically, in our approach, The Cauchy product theorem addresses the discontinuous magnetic permeability change at the slot and tooth interface. The machine’s magnetic saturation effect is considered by combining the actual magnetization characteristics of iron with an iterative algorithm. The general solution for the MVP is solved using the boundary conditions between adjacent subregions. Subsequently, electromagnetic properties such as air-gap flux density, back electromotive force (EMF), and electromagnetic torque are obtained. The accuracy of the analytical model is verified by finite element analysis (FEA) and prototype tests, which proved that the proposed analytical model can consider the iron’s nonlinearity and the magnetic saturation. In addition, the inaccurate overestimation of electromagnetic torque and air-gap magnetic flux density by the conventional SD techniques has also been proven.

A series of direct shear tests under constant normal loading conditions were carried out on specimens of bolted sandstone single-joint treated with different numbers of dry–wet cycles. The experimental results show that the peak shear strength and shear stiffness of bolted sandstone joints were significantly reduced after 12 dry–wet cycles. The decrease in the shear strength of rough joints is more significant than that of flat joints. Due to the decrease in the strength of the surrounding rock, the deformation characteristics of the bolts are significantly affected by the number of dry–wet cycles performed. With an increase in the number of dry–wet cycles, the plastic hinge length of the bolt gradually increases, resulting in an increase in the corresponding shear displacement when the bolt breaks. Compared with the tensile–shear failure mode of the bolts in flat joints, the tensile–bending failure mode arises for bolts in rough joints. A shear curve model describing the whole process of bolted rock joints is established based on the deterioration of rock mechanical parameters caused by dry‒wet cycles. The model proposed considers the change in the friction angle of the joint surface with the shear displacement, which is applied to the derivation of the model by introducing the dynamic evolutionary friction angle parameter. The reasonably good agreement between a predicted curve and the corresponding experimental curve indicates that this method can effectively predict the shear strength of a bolted rock joint involving rough joint under dry–wet cycling conditions.

Structural strengthening solutions typically employ externally bonded reinforcement (EBR) systems with carbon fiber (CF) sheets because of these materials’ lightweight, corrosion resistance, and electromagnetic immunity. However, elevated ambient temperatures can negatively impact the mechanical performance of EBR, as documented in the literature. Therefore, American bridge design specifications assume a concrete surface temperature of 60 °C (140 °F), which reflects the extreme conditions that bridge structures may experience, particularly in regions with intense sunlight and high ambient temperatures. Therefore, sustainable design solutions require a reliable quantification of the effects of temperature. This study extends a recently developed bending test layout and builds the analytical modeling procedure to quantify the stiffness degradation under repeated temperature and mechanical loads. The explicitly obtained equivalent stresses in the tensile concrete determine the stiffness measure independent of the loading condition and sequence. This test program used 12 laboratory samples. All beam samples faced the mechanical load repetitions and entire unloading. Three selected beams were additionally treated at 60 °C for 10 hours in a heating chamber between the loading repetitions. These tests identified a substantial (three times) decrease in the bonding performance of the CF sheets after eight heating rounds. Scanning electron microscopy (SEM) identified the corresponding microstructure changes.

GH4169 thin-walled parts are widely used in aerospace due to their high-temperature, corrosion resistance, and fatigue strength. However, they often deform from machining-induced residual stress, which is a significant unresolved manufacturing challenge. Additionally, initial residual stress from previous steps critically impacts subsequent processes. This study found that the residual stress of side milling of thin-walled parts under smaller cutting parameters is mainly caused by mechanical effects, and the influence of milling heat can be ignored. In this study, an analytical prediction model for residual stress of multi-step side milling thin-walled parts based on the deformation of thin-walled parts is proposed for the first time, which is suitable for smaller cutting parameters. Then, the proposed model is examined the mechanisms through which residual stresses develop during side milling and defined the applicability of model based on specific assumptions. To validate these assumptions, an experimental setup was devloped to simulate the movement of the heat source during milling. Subsequent two-step side milling experiments on GH4169 confirmed the accuracy of the analytical prediction model in predicting the residual stresses of multi-step side milling in thin-walled parts. It was observed that higher equivalent bending stiffness in thin-walled parts correlates with reduced machining deformation. The analytical model also provides a strategic approach to control machining deformation by managing the equivalent bending stiffness of the parts.

The mechanical properties of the steel-plate-reinforced segmental lining are generally determined by the load-bearing capacity of reinforced joints. However, there is a lack of valid calculation methods for compression-bending bearing capacity, and researchers mainly rely on experience and analogy for the design of reinforced joints. This paper proposes an analytical model based on the deformation and stress characteristics of the joint surface to calculate the compression-bending capacity of the steel-plate-reinforced joint. After verifying the applicability of this analytical model through finite element simulations, the evalution rules of the load-bearing capacity of the reinforced joint were attained, followed by a quantitative investigation into the influence of joint parameters on it. The results show that: (1) the bearing capacity curve of the reinforced joint under different axial forces can be separated into two parts, with the maximum ultimate bending moment found at the demarcation point, where the steel plate yielding and joint failure occur simultaneously; (2) the steel plate strength and cross-sectional area have a strong influence on the bearing capacity of the reinforced joint when the axial force is under 0.15RFF, where RFF is the axial force at pure-compression failure); (3) the concrete strength and segment width have a prominent influence on the curve when the axial force is over 0.30RFF; (4) the impact of the fictitious strain, bolt strength, bolt diameter, and bolt location on the bearing capacity is minimal in range and amplitude.

The paper presents an analytical model to study the shear driven debonding of a composite cantilever beam subjected to a point load. The composite structure consists of two elastic beams connected by an interface layer, and the model uses cohesive zone models to simulate the degradation process at the joint. These cohesive zone models are characterized by non-continuous and linear softening in the relationship between shear stress and relative tangential displacement. The results are expressed using non-dimensional parameters, and the model yields quasi-static equilibrium paths that demonstrate snap-back responses in both force and displacement values. The significance of the research lies in its application to structural engineering, where composite materials are extensively used. The study emphasizes the critical role of the interface layer strength in maintaining the structural integrity of composites. The proposed model advances the understanding of debonding by introducing a constitutive relation for the interface that accounts for the step-wise change in mechanical properties. The governing equations for the cantilever beam are derived, considering the equilibrium of forces and moments, and the relative tangential displacement at the interface. The model delineates three stages of interface degradation: no relative slip, plastic deformation, and progressive debonding. The analytical solutions for each stage provide insights into the beam deflection, shear stress, and axial force distribution. This research contributes to the field by offering a more refined analytical approach to study debonding in composite beams, which is essential for improving the design and analysis of composite structures. [ABSTRACT FROM AUTHOR]

Landfills emissions, ranking as the third‐largest anthropogenic source of methane in the atmosphere, pose environmental challenges and threaten public health. The pivotal role of clay as a mitigating agent for methane emission within landfill cover systems cannot be overstated; however, our understanding of methane escape from fractured clay remains limited. This study aims to address the existing gaps by proposing a robust analytical model of methane transport in both fractures and clay matrix. Our investigation also includes a dimensionless analysis to govern the relative significance of diffusion and advection in methane emission from fractured clay, systematically reviewing factors such as the degree of water saturation (Sr) and fracture width. The methane concentration profiles in cracked clay demonstrated escalating sensitivity to Péclet (Pe) numbers, especially when advection dominates transport. Our findings also highlight the prevalence of preferential methane flow with increasing Sr in the clay matrix. The flux of methane emission from fractures at Sr = 0.8 was 130 times greater than that from intact clay. However, the study necessitates considering methane emission from clay matrix, particularly in dry clay conditions (Sr = 0.2 and 0.4). The accumulated methane emission flux from intact clay, more than that emitted from fractures by about 2.5 times at Sr = 0.2, was 1.3 × 10−5 g/m/s. The findings significantly advance the understanding of gas transport in fractured geomaterials, revealing the effect of water saturation and crack width on methane emissions from fractures. Overall, the outcomes emphasize the inclusion importance of methane emission from cracked clay in the design of gas barriers. [ABSTRACT FROM AUTHOR]

The long‐core SDCM pile is a typical type of stiffened deep cement mixing (SDCM) pile, it could be widely exploited in coastal geotechnical engineering because of its high bearing capacity, low settlement, green, and economic advantages. The long‐core SDCM pile is constituted by a PHC pipe pile and cemented soil, the height of the PHC pipe pile is upward than the depth of the cemented soil reinforcement. This study implements a theoretical approach to load transfer analysis of the long‐core SDCM pile under vertical load in layer soil. Herein, the shear constitutive models of the DCM pile‐PHC pipe pile interface and the fictitious soil pile‐PHC pipe pile interface are double exponential models, the compression constitutive model of the soil under the pile and the shear constitutive models of the DCM pile–soil interface and the fictitious soil pile–soil interface are ideal elastic–plastic models. The results obtained from this calculation model can match well with the data from on‐site tests and other analytical solutions. The theoretical model is used to analyze the key parameters LD/LP, DD/DP, Ec, and Ep of the long‐core SDCM pile. The LD/LP and DD/DP are the critical parameters affecting the bearing characteristics, and the minor settlement is affected by the changes of Ec and Ep. [ABSTRACT FROM AUTHOR]

This study proposes a simplified theoretical model to predict the in-plane lateral capacity of unreinforced masonry (URM) walls, addressing limitations in current design guidelines based on semi-empirical approaches. Masonry walls are conceptualized as macroscale units subjected to vertical and lateral loads, with failure mechanisms governed by the effective compression zone. The model applicability is evaluated against comprehensive URM datasets and compared with existing guidelines. The results indicated the outperformance of the proposed model compared to existing guidelines. Additionally, a parametric study explores the influence of primary design parameters on the in-plane lateral capacities of URM walls, offering valuable predictive insights. [ABSTRACT FROM AUTHOR]

The prediction of churning power loss has been a difficult problem in the analysis of spur gears. Thus, an analytical prediction model based on the redefinition of churning power loss and energy transformation is proposed to estimate the churning power of spur gears. Churning power loss is defined as the combination of the power loss due to the drag on the end face, the power loss due to the tangential flow, the power loss due to the acceleration of lubricants in the tooth space, and the power loss due to the centrifugal force. Several comparisons of prediction and experimental results are made and good agreement of those is obtained. Finally, the components of churning power loss under different gears and work conditions are analyzed, and the influences of each part on churning power loss are obtained. [ABSTRACT FROM AUTHOR]

To adapt to complex underwater geological conditions, immersed tunnel projects have gone through the development from rigid and flexible to semirigid immersed tunnels. The stiffness of segment joints and the element joint could reflect the differences in structural characteristics of the three types of immersed tunnels. This paper presents a theoretical model using segment joints, the element joint, and 16 segments for the longitudinal seismic response analysis of the three types of immersed tunnels. Based on the matrix transfer principle, the end boundary conditions and the continuity conditions for the forces and deformations at the segment joints and element joint were considered. Analytical solutions were validated by verifying the established laws. Results indicate that the semirigid immersed tunnel, in contrast to the rigid immersed tunnel, can reduce shear forces and bending moments along the longitudinal direction by using segment joints and the element joint. In addition, compared with the flexible immersed tunnel, the semirigid immersed tunnel has higher overall stiffness and better continuity of deformation between the adjacent soil regions through the prestressed tendons inside the tube element. The semirigid immersed tunnel is a viable solution for complex geological conditions where the strata change every few tens of meters. [ABSTRACT FROM AUTHOR]

A beam's Neutral Axis (NA) is a parameter that has been utilized to detect damage. Its position depends on the geometry of the cross-section and also a member's axial loads. Shifts in its position can indicate changes in either load distribution or geometric characteristics. When considering structures such as cable-stayed bridges where the inclined cables induce significant axial forces, the effect of axial loads on NA position is significant. In this research, a simplified analytical model was developed consisting of the key elements of a cable-stayed bridge (beam, cable, and bearing). The model was loaded with a vertical point load representing a vehicle load. The NA position was calculated beneath the load as it moves over the length of the beam. By changing element properties, one can observe how the NA position behaves in different locations of the beam, due to simulated damage in the beam, cable, or bearing. It was found that changes in NA position can capture not only whether damage has occurred, but also in which component of the structure the damage is located (beam, cable, or bearing). This ability to use NA position for damage identification renders it an excellent parameter for monitoring cable-stayed bridges. [ABSTRACT FROM AUTHOR]

In this paper, we revisit the classical energy transport equation for pure tidal flows in estuaries by including the effects of residual water level and freshwater discharge. Starting from the one-dimensional mass and momentum conservations, we derive analytical expressions for energy flux and its dissipation, which can be used to explore the interaction between tide and river from an energy perspective. It has been shown that the potential energy flux is dominant over the kinetic energy flux, and the energy contribution made by tide-river interaction is negligible compared with that due to tidal flow and freshwater discharge. A critical position corresponding with zero energy flux can be identified, reflecting a balance between along-channel tidal amplitude and residual water level. Assuming the variation of system energy tends to zero, we derive the long-term equilibrium bed profile with a convex-up shape, where we identify the location of a second estuarine turbidity maximum (ETM) at a position determined by the balance between river- and tide-induced energy flux. The dynamic response of tidal propagation extent and critical position with zero energy flux are shown to adjust to reflect seasonal changes towards the formation of a bed profile that is in dynamic equilibrium. [ABSTRACT FROM AUTHOR]