Principle Of Energy Dissipation Research Articles

Effect of different buried depth on the disintegration characteristic of red-bed soft rock and the evolution model of disintegration breakage under cyclic drying-wetting

The disintegration of red-bed soft rock exhibits a strong correlation with various geological disasters. However, the investigation into the evolutionary mechanisms underlying disintegration breakage has not yet received extensive exploration. In order to comprehensively examine the disintegration characteristics of red-bed soft rock, the slake durability tests were conducted to red-bed soft rocks of varying burial depths. Subsequently, an investigation was carried out to examine the disintegration characteristics and the evolution of disintegration parameters, including the coefficient of uniformity (Cu), coefficient of curvature (Cc), disintegration rate (DRE), disintegration ratio (Dr), and fractal dimension (D), throughout the disintegration process. Finally, employing the energy dissipation theory, an energy dissipation model was developed to predicate the disintegration process of samples at various burial depths. The findings demonstrate a decrease in the abundance of large particles and a concurrent increase in the abundance of small particles as the number of drying-wetting cycles increases. Furthermore, as the number of drying-wetting cycles increases, a significant alteration is observed in the content of particles larger than 10 mm, whereas the content of particles smaller than 10 mm undergoes only minor changes. The disintegration parameters, including the curvature coefficient, non-uniformity coefficient, disintegration rate, and fractal dimension, exhibit a positive correlation with the number of drying-wetting cycles. Conversely, the disintegration index demonstrates a decreasing trend with the increasing number of cycles. Nevertheless, as the burial depth increases, a notable trend emerges in the disintegration process, characterized by a gradual increase in the content of large particles alongside a progressive decrease in the content of small particles. Concurrently, the curvature coefficient, non-uniformity coefficient, disintegration rate, and fractal dimension exhibit a gradual decline, while the durability index experiences a gradual increase. In addition, based on the principle of energy dissipation, it is revealed that the surface energy increment of red-bed soft rock increases with the increase of the number of drying-wetting cycles, but decreases with the increase of burial depth. Ultimately, by leveraging the outcomes of energy dissipation analyses, a theoretical model is constructed to elucidate the correlation between surface energy and both the number of drying-wetting cycles and burial depth. This model serves as a theoretical reference for predicting the disintegration behavior of samples, offering valuable insights for future research endeavors.

Energy evolution mechanism of structural surfaces in sandstones with different dips based on the energy principle.

A uniaxial compression test was conducted on sandstone specimens at various inclination angles to determine the energy evolution characteristics during deformation and damage. Based on the principle of minimum energy dissipation, an intrinsic model incorporating the damage threshold was developed to investigate the mechanical properties of sandstone at different inclination angles, and the energy damage evolution during deformation and damage. This study indicated that when the inclination angle of the structural surface remained below 40°, sandstone exhibited varying mechanical properties based on different inclination angles. The peak strain was positively correlated with the inclination angle, whereas the compressive strength and modulus of elasticity showed negative correlations. From an energy perspective, the deformation and damage of sandstone under external loading entail processes of energy input, accumulation, and dissipation. Moreover, higher inclination angles of the structural surface resulted in a smaller absorbed peak strain and a reduced proportion of dissipated energy relative to the energy input, thereby affecting the evolution of energy damage throughout the process. As the inclination angle of the structural surface increased, the absorbed total strain at the peak value decreased, whereas the proportion of the dissipated energy increased. Additionally, the damage threshold and critical value of the rock specimens increased with the inclination angle. The critical value, a composite index comprising the peak strain, compressive strength, and elastic modulus, also increased accordingly. These findings can offer a novel perspective for analyzing geological disasters triggered by fissure zones within underground rock formations.

Multi-component electro-hydro-thermodynamic model with phase-field method. I. Dielectric

We derive a multi-component electro-hydro-thermodynamic (EHTD) model for both leaky and perfect dielectric materials via the principle of energy dissipation. Differing from previous electro-hydrodynamic (EHD) models focusing on fluid mechanics, the electrochemical potential expression is revised and the electric field related term is added to the mass and momentum conservation equations. Resulting from this new correction, we obtain a generalized electro-hydro-thermodynamic stress tensor including the effect of Kortweg and Maxwell stresses. We observe the magnificent impact of the electric field on the thermodynamic equilibrium of the system in two aspects: (i) phase diagram modified by the electric field; (ii) electric field induced surface tension decrease/increase. In addition, the proposed model is validated and shows well conformity with previous analytical solutions in literature. As exemplary applications, we perform phase-field simulations to study the ternary droplet coalescence and spinodal decomposition and observe several typical morphological transformations, such as satellite drop formation and Quincke rotation.

Glassy-like Transients in Semiconductor Nanomaterials.

Glassy behavior is manifested by three time-dependent characteristics of a dynamic physical property. Such behaviors have been found in the electrical conductivity transients of various disordered systems, but the mechanisms that yield the glassy behavior are still under intensive debate. The focus of the present work is on the effect of the quantum confinement (QC) and the Coulomb blockade (CB) effects on the experimentally observed glassy-like behavior in semiconductor nanomaterials. Correspondingly, we studied the transient electrical currents in semiconductor systems that contain CdSe or Si nanosize crystallites, as a function of that size and the ambient temperature. In particular, in contrast to the more commonly studied post-excitation behavior in electronic glassy systems, we have also examined the current transients during the excitation. This has enabled us to show that the glassy behavior is a result of the nanosize nature of the studied systems and thus to conclude that the observed characteristics are sensitive to the above effects. Following this and the temperature dependence of the transients, we derived a more detailed macroscopic and microscopic understanding of the corresponding transport mechanisms and their glassy manifestations. We concluded that the observed electrical transients must be explained not only by the commonly suggested principle of the minimization of energy upon the approach to equilibrium, as in the mechanical (say, viscose) glass, but also by the principle of minimal energy dissipation by the electrical current which determines the percolation network of the electrical conductivity. We further suggest that the deep reason for the glassy-like behavior that is observed in the electrical transients of the nanomaterials studied is the close similarity between the localization range of electrons due to the Coulomb blockade and the caging range of the uncharged atomic-size particles in the classical mechanical glass. These considerations are expected to be useful for the understanding and planning of semiconductor nanodevices such as corresponding quantum dot memories and quantum well MOSFETs.

Research on anti-swing control strategies for three-dimensional overhead cranes with non-stationary enhanced swing angle suppression

In this paper, a non-stationary enhanced swing angle suppression control strategy is proposed to address the issue of excessive swinging angles during the transportation process of a three-dimensional overhead crane. Firstly, in response to the substantial non-stationary initial swing angle resulting from the abrupt increase in driving force during the startup of the overhead crane, we have devised a time-varying damping resistance model. This model is specifically designed to curtail the rapid force surge, subsequently diminishing the swing angle of the payload. Secondly, during the transport phase of the overhead crane, we have established an augmented coupling signal between the displacement tracking error and the payload swing angle tracking error. Drawing upon the principles of energy dissipation, we have devised a nonlinear sway controller. Next, the closed-loop stability of the control system is validated through the use of Lyapunov’s method and the LaSalle invariance principle. Finally, the proposed control strategy’s effectiveness has been substantiated through simulation analysis and physical experiments. This approach not only proves capable of effectively suppressing excessive payload swing angles during the transportation process of the overhead crane but also facilitates the rapid and precise positioning of the payload. This significantly enhances the efficiency of the overhead crane’s transport operations.

Weak Solutions of Mullins–Sekerka Flow as a Hilbert Space Gradient Flow

We propose a novel weak solution theory for the Mullins–Sekerka equation in dimensions d=2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$d=2$$\\end{document} and 3, primarily motivated from a gradient flow perspective. Previous existence results on weak solutions due to Luckhaus and Sturzenhecker (Calc. Var. PDE 3, 1995) or Röger (SIAM J. Math. Anal. 37, 2005) left open the inclusion of both a sharp energy dissipation principle and a weak formulation of the contact angle at the intersection of the interface and the domain boundary. To incorporate these, we introduce a functional framework encoding a weak solution concept for Mullins–Sekerka flow essentially relying only on (i) a single sharp energy dissipation inequality in the spirit of De Giorgi, and (ii) a weak formulation for an arbitrary fixed contact angle through a distributional representation of the first variation of the underlying capillary energy. Both ingredients are intrinsic to the interface of the evolving phase indicator and an explicit distributional PDE formulation with potentials can be derived from them. The existence of weak solutions is established via subsequential limit points of the naturally associated minimizing movements scheme. Smooth solutions are consistent with the classical Mullins–Sekerka flow, and even further, we expect our solution concept to be amenable, at least in principle, to the recently developed relative entropy approach for curvature driven interface evolution.

Study on Failure Energy per Unit Area of Concrete Specimens Based on Minimum Energy Dissipation Theory.

In order to study the strength change of concrete specimens under different loading conditions, based on the principle of minimum energy dissipation, the damage energy per unit area of concrete was studied. By using finite element numerical simulation software for concrete specimens with different failure modes of tension, pressure, bending and torsion, a double-broken line damage constitutive model is adopted. The failure forms of concrete specimens under different loading conditions, as well as the failure area and failure energy of each specimen during loading, are simulated and analyzed. The failure energy per unit area under different failure modes was quantitively calculated, the relationship between the failure area and failure energy consumption under different failure modes was analyzed. The results show that, under different failure modes, the failure area of concrete specimens is different, the energy consumed during failure is different, and the strength is different. However, no matter how the failure mode changes during the failure process, the failure energy W per unit area remains constant and fluctuates in the range of 2.0~6.0 mJ/cm2, which is related to the physical properties of concrete itself.

Non-equilibrium steady states as saddle points and EDP-convergence for slow-fast gradient systems

The theory of slow-fast gradient systems leads in a natural way to non-equilibrium steady states, because on the slow time scale the fast subsystem stays in steady states that are controlled by the interaction with the slow system. Using the theory of convergence of gradient systems depending on a small parameter ɛ (here the ratio between the slow and the fast time scale) in the sense of the energy-dissipation principle shows that there is a natural characterization of these non-equilibrium steady states as saddle points of a so-called B-function where the slow variables are fixed. We give applications to slow-fast reaction-diffusion systems based on the so-called cosh-type gradient structure for reactions. It is shown that two binary reactions give rise to a ternary reaction with a state-dependent reaction coefficient. Moreover, we show that a reaction-diffusion equation with a thin membrane-like layer convergences to a transmission condition, where the formerly quadratic dissipation potential for diffusion convergences to a cosh-type dissipation potential for the transmission in the membrane limit.

Constitutive model of interfacial bond-slip between steel fibers and concrete matrix after exposing to high temperature

In the current study, the bonding properties between two kinds of steel fiber with different shapes and concrete matrix after exposing to high temperatures are investigated experimentally and theoretically. A total of 55 samples were prepared and divided into five groups, subjected to different temperatures ranging from 25 °C to 800 °C, then the residual fiber pull-out strength was measured after naturally cooling down to room temperature. The results of the fibers pulling-out experiment and microstructure analysis show that the bond-slip property of hooked-end steel fiber is better than that of straight steel fiber at any temperature. The influence of temperature on the fiber-pulling performance is mainly due to the change of microstructure in the cement matrix. With the increase of temperature, the cracks of the matrix gradually increase, and the fiber will degrade after 800 °C. According to experimental analysis, a new elastic-plastic constitutive model of bond-slip is developed within the thermodynamic framework. A unified yield function is proposed to describe the pull-out process of fibers of different shapes, which only needs to determine the hardening characteristics. Combined with the principle of free energy dissipation, a damage evolution model of the interface after exposing to high temperature is proposed. The model requires several parameters with definite physical meanings to be obtained from the experiment. Compared with the experimental results, the model proposed in this paper is reliable and provides a basis for further research on the mechanical properties of fiber-reinforced concrete after high temperatures.

Experimental study and evaluation of bonding properties between fiber and cement matrix under sulfate attack

The toughening effect of fibers on cementitious composites mainly comes from the bridging effect of fibers, and the core of the bridging effect depends on the bonding performance of fibers to the cement matrix. To study the fiber-cement matrix bonding performance under the action of sulfate-dry and wet cycles of erosion, fiber pull-out tests with different Na2SO4 solution concentrations (0–15%) and fly ash admixtures (0–30%) were carried out in this paper. Based on the principle of energy dissipation, the mathematical relationship between the toughness index and energy absorption index of fiber-cement-based mortar was established, and a comprehensive evaluation method of fiber-cement matrix bonding performance based on the weight determined by the CRITIC method is proposed. The results show that 15% Na2SO4 solution has a great influence on the erosion rate and erosion degree of interface bonding performance, and the peak load corrosion resistance coefficient is reduced by 43.7%. When the content of fly ash is 20%, the interface transition zone has the best resistance to sulfate attack, and the maximum value of bonding performance index B is 0.59 when the dry-wet cycle is 60 times. The findings can provide a theoretical basis for the interfacial adhesion resistance to sulfate attack and its degradation law under sulfate attack.

Strength deterioration and energy dissipation characteristics of cemented backfill with different gangue particle size distributions

The particle size distribution of gangue is an important factor affecting the strength of backfill body. To uncover the strength deterioration law and energy dissipation characteristics of cemented backfill with different gangue particle sizes, the uniaxial compressive strength mechanical tests were carried out by scanning electron microscopy analysis combined with rock mechanics test system and acoustic emission monitoring equipment. The deformation failure mode, mechanical characteristics, acoustic emission response characteristics and energy dissipation characteristics of backfill samples with different particle size distribution under uniaxial compression were studied. The results shown that: The particle size distribution of gangue material is very important to the performance of backfill body. The compressive strength of the backfill sample with medium particle size was the largest. As the particle size of the gangue increases, the acoustic emission response degree of the backfill firstly increases followed by a subsequent decrease. The acoustic emission ringing count and energy rate reach the peak when the backfill was destroyed. Building upon the principle of energy dissipation and release, the defined energy dissipation ratio was used as the strength deterioration index of the backfill body. The energy dissipation ratio of fine grain size, medium grain size and coarse grain size filling was 19.64%, 7.85% and 12.93%, respectively. When the failure mode of the backfill shifts from tensile failure to shear failure, the energy dissipation ratio decreases from 19.64% to 7.85%. The storage capacity of elastic strain energy in the backfill gradually increases, and the strength degradation degree of backfill gradually decreases.

Functional convergence in slow-growing microbial communities arises from thermodynamic constraints.

The dynamics of microbial communities is complex, determined by competition for metabolic substrates and cross-feeding of byproducts. Species in the community grow by harvesting energy from chemical reactions that transform substrates to products. In many anoxic environments, these reactions are close to thermodynamic equilibrium and growth is slow. To understand the community structure in these energy-limited environments, we developed a microbial community consumer-resource model incorporating energetic and thermodynamic constraints on an interconnected metabolic network. The central element of the model is product inhibition, meaning that microbial growth may be limited not only by depletion of metabolic substrates but also by accumulation of products. We demonstrate that these additional constraints on microbial growth cause a convergence in the structure and function of the community metabolic network-independent of species composition and biochemical details-providing a possible explanation for convergence of community function despite taxonomic variation observed in many natural and industrial environments. Furthermore, we discovered that the structure of community metabolic network is governed by the thermodynamic principle of maximum free energy dissipation. Our results predict the decrease of functional convergence in faster growing communities, which we validate by analyzing experimental data from anaerobic digesters. Overall, the work demonstrates how universal thermodynamic principles may constrain community metabolism and explain observed functional convergence in microbial communities.

Passivity-Based Control of Buck-Boost Converter for Different Loads Research

Normally, the buck-boost converter adopts single or double closed-loop control, and there are differences in control and parameters for different working modes and loads. In this study, a unified control method, the passivity-based control (PBC), is applied to a buck-boost converter for different loads, including constant resistance load (CRL), constant power load (CPL), and battery load. The PBC is a nonlinear control based on energy dissipation principle, and it has strong robustness to parameter interference and external disturbance, and it also has the advantages of simple design and simple implementation. Although many research studies have been conducted before, the voltage and current-related power losses are considered, and different load models are also compared in this research. The detailed mathematical model, control principle, and controller design of the buck-boost converter are thoroughly analysed. In addition, SIMULINK-based simulation results and experimental verification results of different loads are also given in the paper. Also, the PBC has smaller current overshot and smaller current ripples compared with PI control in different loads condition.

Generalized gradient structures for measure-valued population dynamics and their large-population limit

We consider the forward Kolmogorov equation corresponding to measure-valued processes stemming from a class of interacting particle systems in population dynamics, including variations of the Bolker–Pacala–Dieckmann-Law model. Under the assumption of detailed balance, we provide a rigorous generalized gradient structure, incorporating the fluxes arising from the birth and death of the particles. Moreover, in the large population limit, we show convergence of the forward Kolmogorov equation to a Liouville equation, which is a transport equation associated with the mean-field limit of the underlying process. In addition, we show convergence of the corresponding gradient structures in the sense of Energy-Dissipation Principles, from which we establish a propagation of chaos result for the particle system and derive a generalized gradient-flow formulation for the mean-field limit.

Fluid dynamics simulations of pressure and flow control devices in polymer flooding selective use in enhanced oil recovery.

The flow rate in each sand of reservoirs on polymer flooding applications is regulated with flow regulator valves (FRV). Different valves are used depending on their permeability characteristics and reservoir pressure, among other reservoir parameters. However, synthetic polymer solutions generally used in oil recovery processes, like HPAM (Partially Hydrolyzed Polyacrylamide), present high viscosity losses as they flow through regulating valves. Mainly, these viscosity losses happen because commercial water valves designed for waterflooding are used to regulate polymer solutions. To minimize viscosity losses caused by the shear rate in valves, a new flow regulator helicoidal device for polymer flooding was designed and evaluated using computational fluid dynamics (CFD) and experimental tests in a laboratory and a testing bank. Following the energy dissipation principle, this helicoidal valve has a conical reduction and expansion toward the central spiral, creating a smooth flow area reduction. CFD results were compared to laboratory tests, obtaining less than a 15% error for six of the eight cases studied and less than 20% for two. The proposed helicoidal valve of 5 mm presented a reduction of 23 percentage points in the polymeric solution mechanical degradation compared to a commercial water valve. For a 6 mm valve, a reduction of 18 percentage points was achieved with a pressure drop of 500 psi and a polymer concentration of 300 ppm.

Research on overvoltage suppression of hybrid cascaded UHVDC system based on energy dissipation principle

The fault conditions at the receiving end of the hybrid cascaded UHVDC project cause the transmission energy to be blocked, and the sending end cannot respond quickly in a short time, resulting in temporary excess power in the receiving system. A DC controllable self-recovery energy dissipation device for a hybrid cascaded UHVDC project is proposed. The related technical research is carried out, the working principle of the controllable self-recovery energy dissipation device is explained, and the design scheme of the controllable self-recovery energy dissipation device is given. Finally, the feasibility and reliability of the controllable self-recovery energy dissipation device for suppressing system transient overvoltage are verified by simulation. The successful development of the controlled self-recovery energy dissipation device provides a new technology for suppressing transient overvoltage of hybrid cascaded UHVDC faults.

Quantitative prediction of ultra-deep tight sandstone fractures based on the theory of minimum energy dissipation

Structural fractures are key factors that influence natural gas migration and accumulation within ultra-deep tight reservoirs. To obtain a quantitative forecast of the development and distribution of reservoir fractures in the Keshen gas reservoir, we analyzed the characteristics of the region's structural evolution and paleo-tectonic stress field settings. A reasonable geological model of the research area was built based on an interpretation of the geological structure, a test for rock mechanics, and an experiment on acoustic emission. Thereafter, a 3-D paleo-tectonic stress field during the mid-late Himalayan movement was simulated using the finite element method. By introducing the principle of minimum energy dissipation, which to our knowledge, was done for the first time in the field, mechanical constitutive models, rock failure criteria, and fracture parameter calculation models were derived and used to determine the quantitative development of fractures and predict zones prone to fracture development. The fracture distribution in the ultra-deep Keshen gas reservoir is mainly controlled by folds, buried depth, faults, and lithology. Interestingly, even in the strong tectonic compression movement, the stress field was not continuously transmitted forward but showed fluctuation or cyclicity, indicating that fractures might have occurred at each time stage. The predicted areas with developed fractures were consistent with wells having high fracture linear density (i.e., measured results) and in locations with high-producing gas wells. We believe that the novel method in this study can be of great significance to fracture research in other ultra-deep petroliferous basins.

Institutional transformation of society in the light of the sociosynergetic paradigm

The object of theoretical research presented in this article is society as an open non-equilibrium system capable of self-organization. The subject of the study are the factors and driving forces of the institutional transformation of the societal system. The relevance of the study is justified by the prolonged transformational period in the life of Russian society, as well as the increasingly widespread socio-structural crisis phenomena in the world. The scientific problem is determined based on such well-known facts as the low predictability and manageability of the processes of institutional transformation, on the one hand, and the need to reduce the risks associated with them, on the other. Accordingly, the question is raised about the mechanism of institutional transformation, which is proposed to be considered using the principles and provisions of sociosynergetics as a methodological basis. The main element of novelty in this article is the synthesis of neoinstitutional theory with the provisions of sociosynergetics. The study analyzes the process of institutional transformation from the standpoint of the sociosynergetic concept using such categories as energy dissipation, entropy, stationary and nonequilibrium state in their social expression. The characteristics of the evolutionary and crisis stages in the development of the institutional system are given. Attention is focused on the risks of the transformation period and the relationship of its results with the previous period of stability. As a result of the conducted research , the author formulates the following conclusions:1) Subjects of social relations act in accordance with the principle of minimum energy dissipation, as a result of which the foundations of any new order are laid in fluctuations of the previous structure.2) The course of the crisis (transformational) process is adversely affected by both excessive control actions aimed at preserving the previous order, and premature and ill-conceived reforms.3) The prolonged transformation threatens the complete degradation of the societal system due to the depletion of resources needed to reduce entropy.

Research on design and mechanical behavior of a new horizontal connection device of prefabricated shear wall

The mechanical properties of the connection joints/horizontal joints of the fabricated shear wall structure play a vital role in the fabricated structure. In order to improve the seismic performance of the fabricated shear wall structure, a new type of assembled shear wall horizontal connection device is designed and developed based on the principle of energy dissipation in this study. Two horizontal connection devices with different bolt number are designed and manufactured. The device comprises of high-strength bolts and Q345 steel. The dynamic mechanical behaviors are tested for the horizontal connection device under different sinusoidal loading frequencies. The influence laws of different bolt preload, loading frequencies and bolt numbers are explored on the mechanical properties of the device. The effect of friction temperature rise on the mechanical properties of the device is investigated. The experimental results indicate that the device can not only ensure the reliable connection of the structure, but also dissipate significant seismic energy by the internal friction of the device, so as to effectively reduce the seismic response of the structure and protect the main structure. Additionally, the energy dissipation capacity and secant stiffness of the device is proportional to the bolt preload, but the equivalent damping ratio is independent of the preload; the mechanical properties of the horizontal connection device hardly depend on the loading frequency; the increase of the bolt number can considerably enhance the energy dissipation of the device; Both the preload and loading frequency are important factors affecting the temperature rise of the device, but the temperature change has little effect on its mechanical behaviors.

Research on Energy Dissipation Technology and AC Overvoltage Suppression of Sending End in UHVDC Transmission

For suppress the amplitude of overvoltage from HVDC sending terminal, an overvoltage suppression scheme based on the principle of controllable energy dissipation was proposed. The overvoltage mechanism of a weak AC system under the fault of the DC system was analyzed, and the method and operating principle of the CSREDD were proposed. Prototype of the develop CSREDD was tested, which proved correctness about the design. The controllable energy dissipation device has been successfully applied to the ±800kV Lu-Gu UHVDC transmission project. The operation results show that the controllable energy dissipation device can effectively suppress the AC overvoltage.