Dissipative Theory Research Articles

Comprehensive evaluation and stability analysis of ecosystem quality of Yellow River Basin during 1980–2019

AbstractQuality and stability are the basic characteristics of ecosystems, reflecting their structure, process, functional integrity, ability to resist disturbance, self‐regulation, and dynamic balance. The quantitative description of ecosystem quality and stability is an indispensable and important task to promote the ecological protection and high‐quality development of the Yellow River Basin as a major national strategy. In this study, an index evaluation system was constructed from the perspective of system governance, considering the special characteristics of the Yellow River Basin, and an entropy weight model was used to establish a multi‐indicator long time series ecosystem quality evaluation index (EQI) to quantitatively describe the ecological quality changes in the Yellow River Basin over 40 years. The dissipative structure theory and Brussels apparatus model were used to establish quantitative indicators and methods, and provide ideas for the study of ecosystem homeostasis transformation in the Yellow River basin. This study found that: (1) the average EQI value of the Yellow River Basin ecosystem for 40 years was 63.96, the maximum and minimum values were 69.65 and 59.45, respectively; the overall quality showed an oscillating trend of improvement, with an annual increase of 0.03, and the spatial distribution was better in the downstream than in the midstream, and in the midstream than in the upstream; (2) The key factors influencing the system changed gradually from the total water consumption and total annual precipitation in the basin in the early stage to the average income of residents in the last 10 years. (3) The system steady‐state transition force values from 1980 to 2019 were all <0, the steady‐state conversion force of the Yellow River Basin ecosystem was low, but the overall trend was oscillating upward, and the overall trend was getting closer to the critical condition of steady‐state conversion.

Research on thickness problem of pavement asphalt layer based on energy dissipation

Aiming at the problems of low calculation accuracy and poor calculation effect of the traditional calculation method of the optimal thickness of pavement asphalt, a thickness calculation method of pavement asphalt layer based on energy dissipation was proposed. First, according to the energy dissipation theory, the changes of pavement in creep deformation zone and plastic damage zone under different temperature conditions were concretely analyzed, which laid the foundation for subsequent research. Then, proposing to take the lowest energy dissipation control of asphalt pavement as the principle, the energy consumption of asphalt layer was proposed and the optimal thickness of asphalt layer was calculated under the premise of considering the environment and other parameters. Finally, the method was verified by analyzing the changing conditions of the actual failure zone. The verification results show that when the thickness of the asphalt layer reaches the optimal thickness, the main creep deformation zone in the asphalt layer does not change significantly, and the scope of the actual plastic failure zone will be reduced to the minimum. At this time, the energy dissipation of pavement is the lowest, which conforms to the principle that the energy dissipation of the pavement is controlled at the lowest. Moreover, by analyzing the peak value of plastic dissipated energy and the changing situation of the actual plastic failure zone, it is concluded that the most suitable thickness range of asphalt layer is 10 cm∼20 cm. Therefore, through the research of the above, the amount of asphalt used is greatly reduced, and the energy consumption is reduced.

Energy dissipation theory performance of different layup patterns CFRP/aluminium alloy hat-shaped hybrid beams under three-point bending conditions

This study investigates the bending failure behaviour of CFRP-reinforced aluminium alloy hat-shaped hybrid beams under three-point bending conditions. Firstly, three-point-bending experiments are conducted for four kinds of hybrid beams with different layup directions of CFRP. It is found that the layup direction has a more significant impact on the maximum loads. The load carrying capacity of the hybrid beam tends to stabilise around a certain load after decreasing from the maximum value of load. Subsequently, FE models of hybrid beams with inner, external and concurrent reinforced patterns are established to analysis the effect of locations of reinforced structure on the bending characteristics. It is found that the effect of reinforced structure location is influenced by the relative relationship between the thicknesses of aluminium alloy and the CFRP parts. Finally, a theoretical model of hybrid beams under three-point bending condition is proposed to predict the bending characteristics.

PHYSICAL MODEL OF W AND Ti COMPOUND DURING HOT VACUUM ROLLING IN THE SOLID PHASE

The paper considers alternative methods for protecting metal surfaces from corrosion-erosion destruction (CED), based on galvanization or on the use of an oxide film. Their advantages and disadvantages are noted. For the manufacture of CED-resistant tungsten targets, which are used in the subcritical assembly created at the NSC KIPT, it is proposed to use the method of vacuum rolling of W and Ti. A layer of Ti serves as a protective coating. To describe the process of combining these metals, a model description is proposed, which is based on the use of the Rayleigh-Taylor dissipative instability theory (DRTI). An estimate of the values of the parameters of a binary metal system subjected to DRTI is given. The obtained characteristic bonding time of dissimilar metals corresponds to that observed in experiments.

Experimental investigation on the bond-slip behavior between TRC-confined concrete and rebars after exposure to elevated temperatures

In this study, the bond-slip behavior between textile reinforced concrete (TRC)-confined concrete and rebars both at ambient temperature and after ISO 834 standard fire was investigated experimentally through pull-out tests. The failure modes, ultimate load, average ultimate bonding stress and energy consumption were obtained and discussed. Effects of rebar diameters (12 mm, 14 mm and 16 mm), bonding lengths (2.5d, 5d and 7.5d) and high-temperature exposure durations (30 min and 60 min) on the bonding behavior between TRC-confined concrete and rebars were examined emphatically. It was observed that the damage modes of specimens changed from pull-out failure at ambient temperature into splitting failure for both TRC-confined specimens and companion unconfined specimens exposed to high temperatures. The results obtained demonstrated that both the ultimate load and the average ultimate bonding stress can be significantly improved by the utilization of TRC jackets after 30 min exposure, and the increment of the average ultimate bonding stress can reach up to 90% as compared to those unconfined specimens. However, the enhancement of TRC jackets became unobvious after 60 min. Finally, based on test results and Prigogine’s dissipative structure theory, the energy analysis of bond-slip curves was evaluated to verify the enhancement of TRC jackets quantitatively.

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.

Theory of Transfer, Storage and Dissipation of Energy in Circuits

Energy transfer accompanying with current is usually described by using Poynting’s vector. Here, combining Kirchhoff’s law, Joule’s law and Slepian’s postulation, we demonstrate that, for the case of a current travels along a wire, component of total energy flow flux parallel to the wire (CTEFFPW) may be equivalently described by using product of current intensity and electric potential (voltage), furthermore, the law of conversion and conservation of energy accompanying with current, which is equivalent to Poynting’s theorem, may be obtained based on circuit method. Noting that product of current intensity and voltage relates to CTEFFPW instead of the electric power, physical meaning of usual definitions of powers adopted in electric power theory are readdressed. Our work may provide possibility to achieve the long-time expectation that power properties of power systems are described on the basis of Poynting’s theorem and Poynting’s vector, and to address the unsolved problems arised in the electric power theory.

Numerical Analysis of Liquid Potassium Flow and Heat Transfer in a Core for Space Nuclear Reactor Based on Entransy Dissipation Theory

AbstractThe research on the flow and heat transfer of alkali metals is an important technical means to strengthen the heat transfer of the core. In this paper, the 15 cooling channels with different structures are established. Under Re = 2.85 × 104–2.17 × 105, several operating parameters, such as core inlet temperature (T = 350 K, 390 K, 450 K, 550 K, 850 K), fuel rod pitch ratio (P = 1.2, 1.4, 1.6, 1.8, 2.0), and channel shape (triangle and square) on the heat transfer performance are numerically simulated. At the same time, this work introduces an evaluation criterion, entransy dissipation, to measure the irreversibility of the heat transfer process. The results show that the triangular channel has a stronger heat transfer capacity than the square. And the increase of the rod diameter ratio is a positive means to enhance the heat transfer. Among the studied channels, Model “I” (triangle channel, P = 2.0) has the best heat transfer performance. The above results have some guiding value to realize core heat transfer enhancement by adjusting fuel rod arrangement.

Mutual friction and diffusion of two-dimensional quantum vortices

We present a microscopic open quantum systems theory of thermally-damped vortex motion in oblate atomic superfluids that includes previously neglected energy-damping interactions between superfluid and thermal atoms. This mechanism couples strongly to vortex core motion and causes dissipation of vortex energy due to mutual friction, as well as Brownian motion of vortices due to thermal fluctuations. We derive an analytic expression for the dimensionless mutual friction coefficient that gives excellent quantitative agreement with experimentally measured values, without any fitted parameters. Our work closes an existing two orders of magnitude gap between dissipation theory and experiments, previously bridged by fitted parameters, and provides a microscopic origin for the mutual friction and diffusion of quantized vortices in two-dimensional atomic superfluids.

Economic model predictive control with terminal set dynamic programming for tracking control

AbstractThis paper focuses on vehicle tracking control issues with consideration of energy efficiency, ride comfort and tracking performance. To address this issue, an economic model predictive control (EMPC) framework is proposed by taking average performance into account and introducing a time‐varying terminal set. We integrate an economic model predictive controller and a terminal controller with a feedback gain related to the time‐varying terminal set into the proposed EMPC framework. An acceleration‐dependent average constraint is designed and incorporated into the MPC optimization problem to facilitate the convergence of the actual acceleration to the desired one, which enables the vehicle to implement a smooth driving style that boosts energy economy. A tuning factor in the average constraint has the capacity to balance energy consumption and control performance. Under the premise of invariance constraints, a dynamic terminal set is constructed by solving a dynamic programming problem online, which enables an arbitrary location and scale of the terminal set at each iteration by taking the current and predicted tracking errors into account. This allows a reduction in the conservativeness of an economic model predictive controller in the sense of both the region of attraction and the cost bound. Recursive feasibility of the MPC optimization problem and the terminal set dynamic programming is ensured, and average performance is not worse than the performance with an optimal steady‐state operation. Moreover, the convergence of the closed‐loop tracking error to the optimal steady‐state is guaranteed by using the dissipativity theory. The effectiveness of the proposed algorithm is verified by numerical comparisons with different controller parameters and standard EMPC.

A fatigue limit evaluation method based on plastic strain incremental energy dissipation theory

Metallic materials frequently undergo fatigue failure during long-term service. Therefore, the study of fatigue performance detection methods with high precision and wide application ranges is crucial to reduce fatigue failures and accidents of materials and structures. In this study, a plastic strain incremental energy dissipation theory (PSIEDT) is established, and a general expression for fatigue limit is derived with the starting point of the plastic strain increment. Taking 42CrMo4 steel as an example, and its temperature and deformation fields are obtained synchronously using infrared thermal imaging and digital image correlation. Its fatigue limit is evaluated using the energy dissipation theory based on the plastic strain increment. The results show that the relative error between the fatigue limit measurement accuracies of the developed method and the method proposed by Luong is 1.64 %. The relative error of the fatigue limit obtained for the local damage region is only 0.18 %, which has a high measurement accuracy. At the microscopic level, the onset of plastic strain corresponds to a change in the microstructure of the material from reversible deformation (viscoelastic) to permanent deformation (plasticity). Therefore, the strain measurements have higher sensitivity than the temperature measurements. Considering the limited heat release of many materials, the new method has a wide application range, can rapidly obtain material fatigue properties, and has good engineering application prospects.

Transient stability constrained distributed optimal dispatch for microgrids: A state‐based potential game approach

AbstractThe increasing proportion of renewable energy generation (REG) brings severe challenges to the optimal dispatch and stability control of microgrids. On the one hand, the dynamics of REG result in new stability problems. On the other hand, it is difficult to harmonize the benefits of distributed generators (DGs) since they often belong to different owners. To this end, this paper proposes a distributed optimal dispatching method using state‐based potential game theory, which considers both system stability and individual economy. First, an optimal dispatching model is constructed for microgrid containing various DGs. The transient stability constraint (TSC) of microgrid is given based on dissipation theory. Then, by treating each node as an agent, the optimization model is converted into a multi‐agent potential game with a state space. And a distributed algorithm is developed which is capable of handling coupled constraints. To implement the proposed method, updating rules are designed with respect to TSC based on Gerschgorin theorem, and the convergence of the algorithm are discussed. Simulation and experimental results show that the proposed method can maximize the benefits of each DG without the participation of control centre, while the ability of the microgrid to resist large disturbances is also guaranteed.

Creep Behavior and Its Prediction of Saturated Weakly Cemented Medium-Grained Sandstone under Multiaxial Loadings

Weakly cemented medium-grained sandstone in Ordos mining area of China is widely distributed under phreatic water. The creep behavior of saturated rock is important for the stability of water-resisting strata. In this paper, creep mechanical properties of saturated medium-grained sandstone were studied by triaxial rheological test. The results showed that medium-grained sandstone only shows attenuation creep and stable creep under low stress level, and accelerated creep occurs when axial load reaches about 75% of instantaneous compressive strength. The rock samples exhibit volume dilatancy under most loading levels and finally shear fracture. The failure mechanism is the dislocation separation of mineral particles. Based on the energy dissipation theory, the damage evolution equation was modified and introduced into the Burgers model, which can accurately describe the rheological behavior of saturated medium-grained sandstone. The modified model was used to predict the crack initiation time under different deviatoric stresses, which can provide guidance for early warning of water-resisting rock stability.

Microstructure based numerical simulation of the micromechanics and fracture in hypereutectic Al–Mg2Si composites

In the present study, both experimental and numerical examinations were performed to understand the hypereutectic Al–Mg2Si composite's microstructural morphology, mechanical properties and fracture correlation. The innovation of this research includes the micromechanics studies and failure initiation in hypereutectic Al–Mg2Si composite through the compiled induce stress, deformation plasticity and energy dissipation theory subjected to tension. Ultimate tensile strength (UTS), toughness and elongation have decreased, but the yield strength has increased up to 25% Mg2Si addition and then decreased at the composites with 30 wt% Mg2Si because the brittle fracture increases due to the presence of comparatively coarser and dendritic primary Mg2Si particles. Additionally, an increase in the microporosity with the increase in Mg2Si concentration also affects the same. Finite element analysis (FEA) was performed using the Ramberg-Osgood constitutive model and actual microstructure 2D representative volume elements model. The FEA and experimental results have a satisfactory agreement. The fractography unveils the presence of a mix-mode of fracture, i.e. the ductile and the brittle fracture of the composites. Mises and Tresca failure criteria reveal that the distribution of stress is non-homogeneous and stress is localized in the narrow eutectic and irregular Mg2Si phase region, which acts as a crack initiation site. Analysis of the stress triaxiality and equivalent plastic strain distribution shows that void initiation and growth take place during the deformation of the Al–Mg2Si composites. The plastic dissipated energy distribution in deformed RVEs interestingly consents to the von mises stress, plastic strain and stress triaxiality analysis findings.

Open quantum systems with nonlinear environmental backactions: Extended dissipaton theory vs core-system hierarchy construction.

In this paper, we present a comprehensive account of quantum dissipation theories with the quadratic environment couplings. The theoretical development includes the Brownian solvation mode embedded hierarchical quantum master equations, a core-system hierarchy construction that verifies the extended dissipaton equation of motion (DEOM) formalism [R. X. Xu et al., J. Chem. Phys. 148, 114103 (2018)]. Developed are also the quadratic imaginary-time DEOM for equilibrium and the λ(t)-DEOM for nonequilibrium thermodynamics problems. Both the celebrated Jarzynski equality and Crooks relation are accurately reproduced, which, in turn, confirms the rigorousness of the extended DEOM theories. While the extended DEOM is more numerically efficient, the core-system hierarchy quantum master equation is favorable for "visualizing" the correlated solvation dynamics.

An expedition to the islands of stability in the first-order causal hydrodynamics

The recently proposed connection between the Lorentz invariance of stability and the speed of signal propagation has been tested for a first-order relativistic dissipative hydrodynamic theory. The fact that the stability situation in different reference frames agrees with each other only as long as the signal propagation respects causality, has been explicitly established for the theory, which is microscopically derived from the covariant kinetic equation in general hydrodynamic frames with arbitrary momentum-dependent interactions.

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

Due to strong reservoir heterogeneity and low-resolution limit of geophysical data, it is difficult to predict fractures in ultra-deep reservoirs by conventional methods. In this research, we established a novel geomechanical model for prediction of fracture distribution in brittle reservoirs, especially for ultra-deep tight sandstone reservoirs. Methodologically, we intended to introduce the minimum energy dissipation principle considering time variable, combined with the generalized Hooke’s law containing damage variable, and obtained the energy dissipation rate expression corresponding to the energy dissipation process of brittle rocks. Combined with the three-shear energy yield criterion, the Lagrangian multiplier was introduced to deduce and construct the constitutive model and the failure criterion of rocks under the framework of the theory of minimum energy dissipation. Based on the law of conservation of energy, the stress-energy coupling characterization model of fracture density parameter was derived. Finally, all the improved geomechanical equations were incorporated into a finite element software to quantitatively simulate the distributions of tectonic stress filed and fractures based on paleo-structure restoration of Keshen anticline during the middle and late Himalayan periods. Its predictions agreed well with measured fracture density from reservoir cores and image logs.

Rapid fatigue life prediction of butt joint using energy dissipation

This work aims at enabling a rapid life evaluation of Q310NQL2-Q345NQR2 butt joints on the basis of energy dissipation theory within the thermodynamic framework. A Representative Volume Element (RVE) model is first introduced to characterize the energy dissipation response related to two microstructural movements, i.e., the anelastic and inelastic dissipated energy, with increasing stress amplitude. The anelastic dissipated energy is linked to recoverable microstructure motions that cause no damage to the material, while the inelastic energy dissipation is associated with non-recoverable microstructure motions resulting in damage accumulation. Subsequently, the damage-related inelastic energy dissipation is regarded as a valid indicator to deduce a non-linear damage evolution model. Then, a normalized damage model is developed on this basis, and this model is further expanded to quantitatively estimate the high-cycle fatigue life of specimens. Finally, the S-N curves with different probabilities are rapidly estimated by combining with the maximum likelihood method, and the estimated P-S-N curves are well validated by the tested data.

Construction of mental health education system based on dissipative structure theory

Dissipative structure theory, as a new scientific theory, emphasizes that a stable and orderly structure can be formed in the region far from the equilibrium state by exchanging matter and energy with the outside world. The mental health system is an open system, which meets the basic conditions of the application of the dissipative structure. Therefore, applying the dissipative structure theory to the system construction of the mental health education can provide a new theoretical perspective and research method for the construction of the mental health education system. To study the construction of mental health education system from the theory of dissipative structure has an important guiding significance for the mental health education of college students.

Dimension Analysis via Differential Lyapunov and Dissipation Inequalities⋆

Motivated by complex and diverse dynamics in engineering and nature, this paper considers Hausdorff dimension estimates for compact invariant sets of dynamical systems. Our aim is to develop a framework of dimension analysis as an extension of Lyapunov's stability theory as well as Willems’ dissipativity theory. In particular, we extend the existing result by Smith involving Lyapunov inequalities for Hausdorff dimension estimates by employing state-dependent metrics. The obtained result is then combined with the dissipativity framework for studying interconnected systems. This paper is mainly devoted to mathematics but describes several connections with recent works on the differential framework for contraction analysis.