Force Method Research Articles

Prediction method for the tension force of support ropes in flexible rockfall barriers based on full-scale experiments and numerical analysis

This paper proposes a prediction method for the tension force of support ropes in flexible rockfall barriers. The method is based on two full-scale model tests with an impact energy of 3000 kJ, as well as 36 set numerical models featuring varying lengths and impact energies. From the results of full scale tests and numerical models, it is inferred that the tension force at the end of the support rope is significantly less than that at the point of impact, exhibiting an approximate Gaussian attenuation distribution with propagation distance. To account for the attenuation of tensile forces in support ropes, a tensile attenuation coefficient is defined. Through comparative analysis of data obtained from 36 models with varying impact energies and propagation distances, the average attenuation coefficient for the upper support rope is determined to be approximately 0.7, while the average coefficient for the lower support rope is around 0.8. Utilizing the least squares method, a prediction method for the tension force of support ropes in flexible rockfall barriers is established. This method takes into account both the propagation distance and impact energy, enabling accurate predictions of the tensile behavior of the ropes under different conditions. This prediction model provides valuable insights for engineers in the design and optimization of these flexible barriers for rockfall mitigation.

The Impact of Caregiver Pressure to Eat on Food Neophobia in Children with Autism Spectrum Disorder: A Cross-Sectional Study.

(1) Background: With autistic children's high pervasiveness of eating problems and inappropriate feeding behaviors by their caregivers, this study wanted to inspect the connection between caregivers' pressure to eat and food neophobia in these children. (2) Methods: Cross-sectional overview of 160 guardians of kids aged 2 to 7 years. After one-on-one questioning by the researcher, the collected information on the socio-demographic characteristics of the children with autism, caregiver feeding behavior, and new food neophobia (FN) scores was entered into the Questionnaire Star system. (3) Results: The mean FN score was 25.56 ± 6.46. The caregiver's pressure to eat positively related to children's FN (β = 0.164 95% CI, 0.078, 2.163). In these children, we found a negative correlation between FN score and the frequency of vegetable intake (p ≤ 0.001), fruit intake (p ≤ 0.05), aquatic product intake (p ≤ 0.05), and dietary diversity score (p ≤ 0.01), and positively correlated with the frequency of snack intake (p ≤ 0.05). (4) Conclusions: Caregiver pressure to eat was positively associated with high levels of FN in Chinese kids with ASD, which in turn negatively impacted dietary quality. To improve eating habits, caregivers should reconsider their feeding strategies and avoid using forceful methods to ease food neophobia in these children.

Liquid – Solid mass transfer characteristics of a heterogeneous reactor made of separated horizontal woven screens impinged by a submerged jet

The mass transfer characteristics of a submerged liquid jet impinging on a stack of separated screens were investigated by the electrochemical limiting current technique. The effects of changing the jet velocity, the nozzle diameter, and the screens’ porosity were studied. The present mass transfer data were found to be much higher than the data obtained by previous studies on jet impinging on flat surfaces. The mass transfer data also revealed that using the impinging jet greatly enhanced the mass transfer at screen surfaces with respect to other conventional forced convection methods used in previous studies. The mass transfer data were correlated by the equation: ShR=0.253Sc0.33ReN0.66ε0.745 for the conditions: Sc=1898, 8071 ≤ ReN≤ 33631, 0.668≤ε≤ 0.809. The importance of the above equation in the scale up and design of electrochemical and catalytic reactors suitable for diffusion-controlled reactions was highlighted. The calculated high energy utilization efficiency (kA/e) of the reactor lends support to its use in practice in preference to reactors made of flat surfaces impinged by a submerged jet. By supporting catalyst on the screens, the reactor also can replace stirred slurry reactors usually used in conducting biochemical and photochemical reactions in order to eliminate the time consuming and the costly step of separating the final product from the catalyst particles.

Exhaustive Study of Electrical Conductivity in the MNb2−x TixO6–0.5x (M = Mg, Ca, Zn; x = 0, 0.1, 0.2) Columbites

The CaNb2O6 and ZnNb2O6 columbites (Sp.gr. Pbcn) were studied as oxygen ion conductors both theoretically and experimentally. A theoretical approach included geometrical-topological analysis, bond valence site energy (BVSE) and density functional theory (DFT) calculations. The BVSE approach showed the possibility of pure oxygen ions diffusion with migration energies less than 0.45 eV in both compounds. However, DFT calculations indicated the possibility of diffusion of both anions and cations. The single-phases columbites were synthesized by the Pechini method for accurately determine charge carriers type and investigated by impedance spectroscopy, by the Tubandt method, which confirmed the absence of cationic conductivity, and measured the electrical conductivity as a function of oxygen partial pressures. The CaNb2O6 sample was characterized by the pure oxygen-ionic conductivity ∼2 × 10−6 S cm–1 at 800 °C (E a = 0.82 eV), while the ZnNb2O6 had a similar conductivity value due to mixed ionic-electronic contribution (E a = 0.83 eV). The electromotive force method also showed the predominance of the ionic type of conductivity in CaNb2O6, while ZnNb2O6 has a mixed conductivity with ion transport number of about 0.4. Additionally, we synthesized Ti-doped samples MNb2−x Ti x O6–0.5x (M = Mg, Ca; x = 0.1, 0.2) to study the doping effect on conducting properties.

Non-locality of mean scalar transport in two-dimensional Rayleigh–Taylor instability using the macroscopic forcing method

The importance of non-locality of mean scalar transport in two-dimensional Rayleigh–Taylor Instability (RTI) is investigated. The macroscopic forcing method is utilized to measure spatio-temporal moments of the eddy diffusivity kernel representing passive scalar transport in the ensemble averaged fields. Presented in this work are several studies assessing the importance of the higher-order moments of the eddy diffusivity, which contain information about non-locality, in models for RTI. First, it is demonstrated through a comparison of leading-order models that a purely local eddy diffusivity is insufficient to capture the mean field evolution of the mass fraction in RTI. Therefore, higher-order moments of the eddy diffusivity operator are not negligible. Models are then constructed by utilizing the measured higher-order moments. It is demonstrated that an explicit operator based on the Kramers–Moyal expansion of the eddy diffusivity kernel is insufficient. An implicit operator construction that matches the measured moments is shown to offer improvements relative to the local model in a converging fashion.

Seismic displacement analysis of slope reinforced by frame prestressed anchor rod structure

Instability of slope induced by earthquake seriously affects casualties and property losses and hinders earthquake rescue, so the study of slope displacement under earthquake is of great significance. For the slope reinforced by frame prestressed anchor rod structure under earthquake, the calculation method of slope displacement and axial force of anchor rod under seismic action were derived by combing Newmark method and limit analysis method. This method proposed in this paper comprehensively considers the amplification effect of earthquake acceleration on the slope surface, the inertial force of reinforce structure and the dynamic change of axial force of anchor rod. The solution program of this method was compiled in MATLAB and its rationality was proved by a numerical model in FLAC3D software. The results show the slope displacement calculated by the method proposed is consistent with the variation law of slope displacement obtained by traditional methods. Regardless of whether the anchoring force is considered or not, the slope yield acceleration obtained by this method is very close to the slope yield acceleration obtained by the Bishop method. The critical sliding surfaces obtained by the two methods are very close, and the sliding points are located at the foot of the slope. Compared with the Bishop method, this method can consider the amplification effect of seismic force on the free surface of the slope and the gravity of the supporting structure. Ignoring the change of the axial force of anchor rod will make the slope displacement larger, while not considering the amplification effect of the seismic acceleration on the slope surface and the gravity of the reinforce structure will make the slope displacement smaller. This method proposed in this paper comprehensively considers the above factors and is more accurate. In the process of landslide mass sliding, the axial force of the anchor rods increase gradually, and the growth rate of the axial force of the lower anchor rods are larger than that of the upper anchor rods. The increase of anchor rod prestress and elastic modulus will reduce the seismic displacement of the slope, and the increase of the dip angle of the anchor rod will increase the seismic displacement of the slope. The dip angle of the anchor rod should be minimized without affecting the grouting effect of the anchor rod.

Formation of philosophical and legal ideas of Taoism

The article examines the philosophical trend of Taoism, which arose in ancient Chinese philosophy around the VI-V centuries BC. e. The founder of Taoism is Lao-Tzu, who formulated the system based on the principle of knowing the Tao as the only true path. The purpose of this article is to analyze the evolution of philosophical and legal concepts that arose within the framework of Taoism. The interaction between the key principles of Taoist philosophy and the legal system is highlighted, as well as the impact of this interaction on the formation of socio-cultural norms and values is evaluated.
 Lao Tzu’s Tao Te Ching defines the key concepts and ideas of Taoism. Attention is drawn to the important statements of Lao Tzu, which reveal the relationship between Taoism and life, morality and nature.
 The article examines the views of various scientists on the principles of Taoism. The text also analyzes the main principles of Taoism, expressed in the «Tao-De-Ching». The Tao is considered as the ruling law of all that exists, inaccessible to the senses, associated with natural chaos. The principle of «u-wei» is defined as a return to the original nature.
 Special attention is paid to the principle of non-intervention, which means a unique approach to state management. According to the opinion of one of the scientists identified in this work, the ruler, following the principles of Taoism, should not intervene by force in natural processes, but should act in accordance with the natural properties of things.
 Emphasis is placed on the fact that with the help of such principles, the state, according to the teachings of Lao Tzu, develops in its own way, without artificial intervention. Criticism of the government that uses force and artificial methods shows the ineffectiveness of such an approach from the point of view of Taoism. The article also examines the concept of the culture of law in the context of Taoism, where adherence to the principles of this teaching ensures legitimacy and legalization, the expression of the will of society, not the state. Emphasizes the perceived need for citizens to adhere to Taoist principles in order to achieve spiritual and physical self-improvement in relation to Taoism.
 Overall, the article reveals the key aspects and development of Taoism as an important philosophical direction in the ancient Chinese context.

A computational approach to modeling flow-induced large deformation of thin-walled compliant vessels

We present a computational method capable of modeling 3D flow-induced deformation of thin, highly compliant, hyperelastic vessels conveying viscous, inertial fluid. The method can uniformly consider vessel extension and collapse. Very large inflation, transient deformation, complex flow features as well as highly complex buckling shapes are well resolved by this method. The methodology combines finite volume and spectral methods for fluid motion, finite element method for structural mechanics of the vessel wall, and the immersed boundary method for two-way coupling between the wall and fluid. A hybrid of the continuous forcing and the ghost node methodologies capitalizing on the strengths of each is developed. The method avoids the surface instability encountered with the continuous forcing methods, as well as the need for domain remeshing as required in the iterative and partitioned approaches. The vessel wall can follow linear or nonlinear (strain softening and hardening) material models, and the fluid inertia can vary over a wide range. We demonstrate the versatility of the method by considering vessel inflation and collapse with large, complex, and transient deformation. Remarkable differences in vessel inflation at low versus moderate inertia are observed; this includes steady versus oscillatory motion, emergence of flow recirculation and pressure wave reflection which are well resolved. For the collapsing vessels, well-defined shapes with different buckling modes as well as highly complex buckling with fine surface folds are predicted. Additionally, a second-order correction to the well-known law of Laplace is developed and used to validate our computational results for vessel inflation.

Research on Ventilation Simulation Technology for Large Section Gas Tunnel Construction

In order to solve the problem of gas overrun during the construction of large section gas tunnel, this paper takes the Baima Tunnel as the engineering background and uses fluent numerical simulation software to study the gas transport law of the tunnel under different ventilation methods. The results indicate that when the tunnel is excavated for 1200m, the forced ventilation method cannot effectively solve the problem of gas overrun on the heading face. After adopting the gallery ventilation method, the gas concentration on the heading face decreases to less than 1%, which effectively solved the problem of gas overrun on the heading face and provided assistance for the safe construction of the project..

Chromatin image-driven modelling

The challenge of modelling the spatial conformation of chromatin remains an open problem. While multiple data-driven approaches have been proposed, each has limitations. This work introduces two image-driven modelling methods based on the Molecular Dynamics Flexible Fitting (MDFF) approach: the force method and the correlational method. Both methods have already been used successfully in protein modelling. We propose a novel way to employ them for building chromatin models directly from 3D images. This approach is termed image-driven modelling. Additionally, we introduce the initial structure generator, a tool designed to generate optimal starting structures for the proposed algorithms. The methods are versatile and can be applied to various data types, with minor modifications to accommodate new generation imaging techniques.

Design and Analysis Method of Piezoelectric Liquid Driving Device with Elastic External Displacement.

In piezoelectric drive, resonant drive is an important driving mode in which the external elastic force and electric drive signal are the key factors. In this paper, the effects of the coupling of external elastic force and liquid parameters with the structure on the vibrator resonance frequency and liquid drive are analyzed by numerical simulation. The fluid-structure coupling model for numerical analysis of the elastic force was established, the principle of microdroplet generation and the coupling method of the elastic force were studied, and the changes in the resonant frequency and mode induced by the changes in the liquid parameters in different cavities were analyzed. Through the coupled simulation and calculation of the pressure and deformation of the cavity, the laser vibration measurement test was carried out to test the effect of the vibration mode analysis. The driving model of the fluid jet driven by the elastic force on the piezoelectric drive was further established. The changing shape of the fluid jet under different elastic forces was analyzed, and the influence law of the external elastic force on the change in the droplet separation was determined. It provides reference support for further external microcontrol of droplet motion.

A Method to Simulate an Outwardly Propagating Turbulent Premixed Flame at Constant Pressure

An outwardly propagating premixed flame in homogeneous isotropic turbulence at constant pressure is considered one of canonical configurations to study turbulent premixed flames. In this paper, a surface forcing method to prevent the undesirable influence of the boundary-condition-induced backflow on the flame evolution, while maintaining the constant pressure, in the simulation of the outwardly propagating flame is presented. The method is validated for laminar and turbulent flames. The results show that the present method well preserves the characteristics of turbulence and of an outwardly propagating flame, without the undesirable influence of the boundary condition, by feeding the homogeneous turbulence relative to the velocity field induced by the volume expansion due to heat release to the domain in which the flame develops.

Effects of wind-induced static angle of attack on flutter performance of long-span bridges using 2D bimodal and 3D multimodal analysis

Flutter performance of long span bridges is directly affected by winds featured with large angles of attack (AoAs) in typhon climates and mountainous areas. Flutter critical wind speed and flutter derivatives (FDs) of a streamlined closed-box girder under various initial AoAs are obtained by free and forced vibration wind tunnel tests of a section model, based on which the two-dimensional(2D) and three-dimensional (3D) flutter performance and evolution mechanisms are further investigated. The results indicate that FDs identified at small vibration amplitudes through different forced vibration control methods, i.e., fixing wind speed or vibration frequency, in wind axis or body axis are almost identical. The flutter performance of the closed-box girder is susceptible to the AoA. The flutter critical wind speed changes significantly with the initial AoA due to the nonlinear variation of some typical FDs. The sign of A2* shifts from negative to positive and the reduced wind speed associated with the sign change becomes lower as the initial AoA increases, which worsens the flutter performance. The flutter critical wind speed would significantly decrease because of the consideration of the static additional AoA in the range of positive initial AoA. In addition, the participation of multi modes and different longitudinal distribution of static additional AoA are taken into consideration in 3D numerical analysis, which have little influence on the flutter critical wind speed of long span bridges between the 2D and 3D numerical analysis.

The local potential variation mapping including thermoelectromotive force in nanocomposite materials under non-thermal equilibrium

Thermoelectric nanocomposite materials are attracting much attention due to their high thermoelectric performance brought by effectively combining thermoelectric properties of the matrix and introduced nanostructures. However, understanding the mechanism of Seebeck coefficient enhancement brought in nanocomposite materials is difficult because there are no measurement methods of thermoelectromotive force V TE on the nanoscale. In this study, we demonstrate that the controlled temperature gradient Kelvin force microscopy (T-KFM) measurement we developed in 2021 can be applied to nanocomposite films. We observe temperature difference ΔT-induced vacuum level V vac variation, which is related to V TE, in PEDOT:PSS/Si nanowire nanocomposite films using T-KFM. The large ΔT-induced V vac variation at the tops of Si nanowires is generated, which is mainly explained by the larger Seebeck coefficient value of the Si nanowire. This application of T-KFM to the nanocomposites highlights that T-KFM will be a powerful tool for the development of nanocomposite materials with controlled thermoelectric properties on the nanoscale.

Explicit Model Predictive Cascade-Free Direct Force and Torque Control of Quadrotors

High-performance control of quadrotors' force and torques is the basis for achieving excellent trajectory tracking. However, the conventional method indirectly controls the force and torques by controlling four permanent magnet synchronous motors' speeds, resulting in poor dynamic performance and static deviations when pneumatic parameters mismatch. Dedicated to achieving high-dynamic and high-accuracy control of force and torques, an explicit model predictive (EMP) cascade-free direct force and torque control method is proposed. Firstly, defining force current and torque currents, whereby a new structure is proposed. Then, dynamics of the quadrotor and motor are fused to design the linear robust predictive models of force and torques. Accordingly, the EMP controller is constructed to replace the traditional cascaded speed solution module and four speed controllers uniformly. The EMP controller generates the optimal current commands directly from the force and torque commands, realizing direct control without the speed loop. The new structure makes it possible to solve the pneumatic parameter mismatch problem with an auxiliary extended state observer, obtaining offset-free control. The proposed method optimizes the dynamic performance and steady-state accuracy of force and torques and improves the system's robustness. Finally, the proposed method's feasibility is verified by experiments.

Numerical investigation of water entry of hydrophobic spheres

We perform numerical simulations to study the dynamics of the entry of hydrophobic spheres in a pool of water. To track the air-water interface during the translation of the sphere in the pool of water, we use the volume of fluid model. The continuum surface force method computes the surface tension force. To represent the hydrophobic surface properties, we use wall adhesion in terms of a static contact angle. We perform simulations with different diameters and impact speeds of the sphere. Our simulations capture the formation of different types of air cavities, pinch-offs of these cavities, and other finer details similar to the experiments performed at the same parameters. Finally, we compare the drag force among the different hydrophobic cases. We further perform simulations of hydrophilic spheres impacting the pool of water and compare the drag force with the analogous hydrophobic cases. We conclude that the spheres with hydrophobic surfaces encounter a lower drag than their hydrophilic counterparts. This lower drag of the hydrophobic spheres is attributed to the formation of the air cavity by the hydrophobic surfaces while translating through the pool of water, which reduces the area of the sphere in contact with water. In contrast, no such air cavity forms in the case of hydrophilic spheres.

Comparative Study of Static and Dynamic Analysis of Multistoried Building

In a moderate seismic activity, relying solely on the static force method to estimate the seismic force assessing the vulnerability and behaviour of RCC buildings under seismic loads is insufficient. The seismic response of the building system is highly influenced by the analysis method adopted. In the past years, static approaches were preferred due to their simplicity, although these methods provided safe design, they may have been overly cautious. Dynamic analysis, on the other hand, is a fundamental aspect of structural mechanics, that describes and predicts the behaviour of structures subjected to dynamic loads. Dynamic load includes wind, imposed load, earthquake, etc. Dynamic analysis techniques, such as modal analysis, time history analysis, and dynamic displacement analysis. RCC structures are mainly designed to resist static load. This process of ignoring dynamic events sometimes becomes the cause of disasters, especially in the case of earthquakes. This research paper provides information on the comparison of various parameters in static and dynamic analysis. Two RCC multistoried residential buildings (g+10 and g+25) acting on seismic zone IV are analyzed using the static analysis method and response spectrum method with ETABS 16. The research investigates the effect on various structural parameters such as story displacement, story drift, and support reactions. The results are compared and evaluated to assess the performance of the response spectrum method over the static analysis method.

Electrochemical behavior and effective extraction of Er in fused LiCl-KCl eutectic

For the efficient electrolytic extraction of Er from spent nuclear fuel, a series of electrochemical methods was used to research the electrochemical behavior of Er(III) in the LiCl-KCl system on inert (Mo) electrode and on reactive (Ni) electrodes. On the inert Mo electrode, the reduction of Er(III) to Er(0) is a one-step with three-electron and quasi-reversible reaction process. Meanwhile, the apparent generation Gibbs free energy and activity coefficients of Er(III) on the inert electrode were determined. Thereafter, the electrochemical reduction of Er(III) on the Ni electrode was emphatically investigated. Er(III) is reduced at a corrected potential owing to the formation of Ni-Er alloys. In addition, thermodynamic parameters such as partial excess Gibbs free energy change of Er in Ni, activity and apparent generation Gibbs free energy of the Ni-Er alloys were determined by the electromotive force method. Finally, different Ni-Er alloys were produced using potentiostatic electrolysis on the Ni cathode by controlling different potentials. Moreover, electrolytic extraction was carried out on the Ni cathode at the potential of –2.0 V, and the separation efficiency of Er reaches 99.72%, which proves the practicability of separating Er from LiCl-KCl eutectic on the reactive Ni cathode.

Fracture criteria and initiation mechanism of concrete based on material configurational mechanics

AbstractIn this study, the interaction force between an in‐plane elliptical inclusion and a crack is evaluated using the Eshelby equivalent inclusion and material configurational force method. The toughening effect of coarse aggregates on concrete is investigated. The fracture criteria for mixed‐mode cracks based on the characteristics of the crack‐tip plastic zone assessed by the principal configurational stress difference are proposed and verified by experimental results in the literature. The fracture probability is then used to improve the fracture criteria, and the dimensionless factor associated with stress intensity factors is introduced to determine the fracture probability. Additionally, the volume fraction of coarse aggregates, the age and fatigue life of concrete are considered in the present fracture criteria. Theoretical studies show that the interaction between a crack and a hard or soft inclusion exhibits mutual repulsion and attraction. The size and shape of the crack‐tip plastic zones assessed by the Mises stress and the principal configurational stress difference are essentially the same. The fracture load envelopes increase with the increase in the volume fraction of coarse aggregates and the age of concrete and shrink with the increase in the life ratio.

Fast and exact fixed-radius neighbor search based on sorting.

Fixed-radius near neighbor search is a fundamental data operation that retrieves all data points within a user-specified distance to a query point. There are efficient algorithms that can provide fast approximate query responses, but they often have a very compute-intensive indexing phase and require careful parameter tuning. Therefore, exact brute force and tree-based search methods are still widely used. Here we propose a new fixed-radius near neighbor search method, called SNN, that significantly improves over brute force and tree-based methods in terms of index and query time, provably returns exact results, and requires no parameter tuning. SNN exploits a sorting of the data points by their first principal component to prune the query search space. Further speedup is gained from an efficient implementation using high-level basic linear algebra subprograms (BLAS). We provide theoretical analysis of our method and demonstrate its practical performance when used stand-alone and when applied within the DBSCAN clustering algorithm.