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Keywords = maximum entropy production principle

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22 pages, 1439 KB  
Article
A Thermodynamic Closure Model for Titan’s Surface Temperature: Its Long-Term Stability Anchored to Methane’s Triple Point
by Hsien-Wang Ou
Geosciences 2026, 16(2), 90; https://doi.org/10.3390/geosciences16020090 - 22 Feb 2026
Viewed by 402
Abstract
We develop a minimal thermodynamic model to predict Titan’s surface temperature based on radiative–convective equilibrium and the principle of maximum entropy production (MEP). The model retains only the essential atmospheric constituents: gaseous methane, which absorbs both longwave and near-infrared radiation, and stratospheric haze, [...] Read more.
We develop a minimal thermodynamic model to predict Titan’s surface temperature based on radiative–convective equilibrium and the principle of maximum entropy production (MEP). The model retains only the essential atmospheric constituents: gaseous methane, which absorbs both longwave and near-infrared radiation, and stratospheric haze, which scatters and absorbs solar flux. Subject to Clausius–Clapeyron scaling of methane vapor pressure together with energy balances at the surface, tropopause, and stratopause, the model links the convective flux to the surface temperature, which exhibits a pronounced maximum due to competing radiative effects of tropospheric methane. As the surface warms, enhanced greenhouse effect would strengthen the convection, whereas the rising anti-greenhouse effect would suppress convection. The resulting convective peak corresponds to MEP, which thus selects a surface temperature slightly above methane’s triple point. To assess its long-term evolution, we consider a 20% dimmer early Sun and a hypothetical 20% enrichment of the oceanic methane. Even in combination, they only cool the surface by ~2 K, in sharp contrast to the ~20 K cooling inferred in studies that prescribe haze abundance. This study suggests a critical role of self-adjusting haze in providing the internal degree of freedom necessary for MEP closure, thereby stabilizing Titan’s temperature. Full article
(This article belongs to the Section Climate and Environment)
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10 pages, 291 KB  
Proceeding Paper
Maximum Entropy Production for Optimizing Carbon Catalysis: An Active-Matter-Inspired Approach
by Klaus Regenauer-Lieb, Manman Hu, Hui Tong Chua, Victor Calo, Boris Yakobson, Evgeny P. Zemskov and
Phys. Sci. Forum 2025, 12(1), 16; https://doi.org/10.3390/psf2025012016 - 15 Nov 2025
Viewed by 723
Abstract
The static topology of surface characteristics and active sites in catalysis overlooks a crucial element: the dynamic processes of optimal pattern formation over time and the creation of intermediate structures that enhance reactions. Nature’s principle of coupling reaction and motion in catalytic processes [...] Read more.
The static topology of surface characteristics and active sites in catalysis overlooks a crucial element: the dynamic processes of optimal pattern formation over time and the creation of intermediate structures that enhance reactions. Nature’s principle of coupling reaction and motion in catalytic processes by enzymes or higher organisms offers a new perspective. This work explores a novel theoretical approach by adding the time dimension to optimise topological variations using the Maximum Entropy Production (MEP) assumption. This approach recognises that the catalyst surface is not an unchanging energy landscape but can change dynamically. The time-dependent transport problem of molecules is here interpreted by a non-equilibrium model used for modelling and predicting dynamic pattern formation in excitable media, a class of active matter requiring an activation threshold. We present a nonlocal reaction–cross-diffusion (RXD) formulation of catalytic reactions that can capture the catalyst’s interaction with the target molecule in space and time. The approach provides a theoretical basis for future deep learning models and multiphysics upscaling of catalysts and their support structures across multiphysics fields. The particular advantage of the RXD approach is that it allows each scale to investigate dynamic pattern-forming processes using linear and nonlinear stability analysis, thus establishing a rule base for developing new catalysts. Full article
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21 pages, 3111 KB  
Article
Unraveling the Spatial Dynamics and Global Climate Change Response of Prominent Tropical Tree Species in Asia: Symplocos cochinchinensis and Beyond
by Haijun Li, Lihao Guo, Jingrui Zhang, Suile Li and Bo Liu
Forests 2025, 16(5), 715; https://doi.org/10.3390/f16050715 - 23 Apr 2025
Viewed by 1331
Abstract
The tropical tree species Symplocos cochinchinensis plays a crucial role in ecological restoration and serves as a resource for traditional medicine, dyeing, and timber production. Assessing its distribution patterns and adaptive responses to global climate change is essential for maintaining ecosystems and developing [...] Read more.
The tropical tree species Symplocos cochinchinensis plays a crucial role in ecological restoration and serves as a resource for traditional medicine, dyeing, and timber production. Assessing its distribution patterns and adaptive responses to global climate change is essential for maintaining ecosystems and developing conservation strategies. This study elucidates the spatial distribution patterns and projects potential geographic shifts of the widely distributed tropical species S. cochinchinensis under climate change scenarios. A compilation of data from global and local herbaria and databases yielded 5050 occurrence records, covering the majority of its native range in the tropics and subtropics. We modeled the species’ potential habitats using the maximum entropy (MaxEnt) principle for current, 2050, and 2070 climate scenarios under high-emission SSP585. Our analysis reveals that sampling bias substantially influences the observed distribution patterns of S. cochinchinensis. Predictions indicate a decrease in barely suitable habitats and an increase in areas deemed highly suitable, suggesting climate change stress and an ecological niche shift towards areas with favorable microclimates with “Precipitation of Wettest Month” (Bio 13) and “Mean Temperature of Wettest Quarter” (Bio 8). Our findings reveal S. cochinchinensis’s adaptive resilience, offering valuable insights for developing strategies and conservation management in Southeast Asia, as well as a reference for the response of other common tropical species to climate change. Full article
(This article belongs to the Section Forest Meteorology and Climate Change)
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17 pages, 885 KB  
Review
Maximum Entropy Production Principle of Thermodynamics for the Birth and Evolution of Life
by Yasuji Sawada, Yasukazu Daigaku and Kenji Toma
Entropy 2025, 27(4), 449; https://doi.org/10.3390/e27040449 - 21 Apr 2025
Cited by 7 | Viewed by 5078
Abstract
Research on the birth and evolution of life are reviewed with reference to the maximum entropy production principle (MEPP). It has been shown that this principle is essential for consistent understanding of the birth and evolution of life. First, a recent work for [...] Read more.
Research on the birth and evolution of life are reviewed with reference to the maximum entropy production principle (MEPP). It has been shown that this principle is essential for consistent understanding of the birth and evolution of life. First, a recent work for the birth of a self-replicative system as pre-RNA life is reviewed in relation to the MEPP. A critical condition of polymer concentration in a local system is reported by a dynamical system approach, above which, an exponential increase of entropy production is guaranteed. Secondly, research works of early stage of evolutions are reviewed; experimental research for the numbers of cells necessary for forming a multi-cellular organization, and numerical research of differentiation of a model system and its relation with MEPP. It is suggested by this review article that the late stage of evolution is characterized by formation of society and external entropy production. A hypothesis on the general route of evolution is discussed from the birth to the present life which follows the MEPP. Some examples of life which happened to face poor thermodynamic condition are presented with thermodynamic discussion. It is observed through this review that MEPP is consistently useful for thermodynamic understanding of birth and evolution of life, subject to a thermodynamic condition far from equilibrium. Full article
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19 pages, 306 KB  
Review
The Significance of the Entropic Measure of Time in Natural Sciences
by Leonid M. Martyushev
Entropy 2025, 27(4), 425; https://doi.org/10.3390/e27040425 - 14 Apr 2025
Cited by 2 | Viewed by 2397
Abstract
The review presents arguments emphasizing the importance of using the entropic measure of time (EMT) in the study of irreversible evolving systems. The possibilities of this measure for obtaining the laws of system evolution are shown. It is demonstrated that EMT provides a [...] Read more.
The review presents arguments emphasizing the importance of using the entropic measure of time (EMT) in the study of irreversible evolving systems. The possibilities of this measure for obtaining the laws of system evolution are shown. It is demonstrated that EMT provides a novel and unified perspective on the principle of maximum entropy production (MEPP), which is established in the physics of irreversible processes, as well as on the laws of growth and evolution proposed in biology. Essentially, for irreversible processes, the proposed approach allows, in a certain sense, to identify concepts such as the duration of existence, MEPP, and natural selection. EMT has been used to generalize prior results, indicating that the intrinsic time of a system is logarithmically dependent on extrinsic (Newtonian) time. Full article
(This article belongs to the Section Time)
22 pages, 609 KB  
Article
A New Metric for CO2 Emissions Based on the Interaction Between the Efficiency Ratio Entropy/Marginal Product and Energy Use
by Second Bwanakare, Marek Cierpiał-Wolan and Daniel Rzeczkowski
Energies 2025, 18(8), 1895; https://doi.org/10.3390/en18081895 - 8 Apr 2025
Cited by 2 | Viewed by 1106
Abstract
In an era of growing climate concerns and complex environmental policy challenges, novel approaches for accurate carbon emissions measurement are urgently needed. This article introduces an innovative approach for predicting carbon dioxide emissions by analyzing the interaction between energy consumption and production efficiency, [...] Read more.
In an era of growing climate concerns and complex environmental policy challenges, novel approaches for accurate carbon emissions measurement are urgently needed. This article introduces an innovative approach for predicting carbon dioxide emissions by analyzing the interaction between energy consumption and production efficiency, measured through an entropy-to-marginal product ratio. Unlike conventional metrics such as Eurostat measurements or the Kaya identity, our framework establishes explicit connections to fundamental physical laws governing energy transformation while offering flexible elasticity parameters that capture non-linear relationships between efficiency improvements and emission reductions. The research combines theoretical modeling with empirical validation across ten European countries, demonstrating how the entropy-based methodology accounts for both production complexity and energy efficiency where traditional linear models fall short. Analysis reveals that energy-efficient countries demonstrate lower entropy maximization under stable conditions, indicating a direct relationship between operational efficiency and environmental impact. Although the model demonstrates strong predictive capabilities with an exceptional accuracy/information cost ratio, limitations exist in achieving accuracy in some country cases. This study concludes by evaluating these strengths and constraints, acknowledging the need for extended time series analysis and sector-specific applications, and providing clear directions for future research that bridge this promising theoretical contribution with practical environmental policy applications. Full article
(This article belongs to the Collection Feature Papers in Carbon Capture, Utilization, and Storage)
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24 pages, 4145 KB  
Article
Using Entropy Metrics to Analyze Information Processing Within Production Systems: The Role of Organizational Constraints
by Frits van Merode, Henri Boersma, Fleur Tournois, Windi Winasti, Nelson Aloysio Reis de Almeida Passos and Annelies van der Ham
Logistics 2025, 9(2), 46; https://doi.org/10.3390/logistics9020046 - 26 Mar 2025
Cited by 5 | Viewed by 2567
Abstract
Background: The literature on measuring the complexity of production systems employs the graph and information theory. This study analyzes these systems and their coordination under varying states of control, with a focus on the probability of unfavorable events and their temporal characteristics. [...] Read more.
Background: The literature on measuring the complexity of production systems employs the graph and information theory. This study analyzes these systems and their coordination under varying states of control, with a focus on the probability of unfavorable events and their temporal characteristics. Methods: Coordination systems are represented as temporal networks, using entropy and node influence metrics. Two case studies are presented: a factory operating under the principles of the Toyota Production System (TPS) with adjacent (local) coordination and andon (global) coordination and a university obstetrics clinic with only adjacent (local) coordination. Results: Adjacent coordination leads to zero entropy in 38.40% of all situations in the TPS example, contrasted to 76.62% in the same system with andon coordination. Degree centrality of nodes outside of zero-entropy situations exhibits higher average and maximum values in andon coordination networks, compared to those with adjacent coordination in TPS. Entropy values in the university obstetric clinic range from 0.92 to 2.23, average degrees vary between 3 and 4.08, and maximum degrees range from 7 to 9. Conclusions: Coordination systems modeled as temporal networks capture the evolving nature of centralizing and decentralizing coordination in production systems. Full article
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18 pages, 12593 KB  
Article
Modeling of the Potential Distribution Areas Suitable for Olive (Olea europaea L.) in Türkiye from a Climate Change Perspective
by Muhammed Mustafa Özdel, Beyza Ustaoğlu and İsa Cürebal
Agriculture 2024, 14(9), 1629; https://doi.org/10.3390/agriculture14091629 - 17 Sep 2024
Cited by 18 | Viewed by 5539 | Correction
Abstract
Türkiye is one of the first regions where olives were domesticated, and olives reflect the country’s millennia-old agricultural and cultural heritage. Moreover, Türkiye is one of the leading nations in olive and olive oil production in terms of quality and diversity. This study [...] Read more.
Türkiye is one of the first regions where olives were domesticated, and olives reflect the country’s millennia-old agricultural and cultural heritage. Moreover, Türkiye is one of the leading nations in olive and olive oil production in terms of quality and diversity. This study aims to determine the current and future distribution areas of olives, which is important for Türkiye’s socio-economic structure. For this purpose, 19 different bioclimatic variables, such as annual mean temperature (Bio1), temperature seasonality (Bio4), and annual precipitation (Bio12), have been used. The RCP4.5 and RCP8.5 emission scenarios of the CCSM4 model were used for future projections (2050 and 2070). MaxEnt software, which uses the principle of maximum entropy, was employed to determine the current and future habitat areas of the olives. Currently and in the future, it is understood that the Mediterranean, Aegean, Marmara, and Black Sea coastlines have areas with potential suitability for olives. However, the model projections indicate that the species may shift from south to north and to higher elevations in the future. Analyses indicate that the Aegean Region is the most sensitive area and that a significant portion of habitats in the Marmara Region will remain unaffected by climate change. Full article
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18 pages, 1377 KB  
Study Protocol
Application of Research on Risk Assessment of Roadway Roof Falls Based on Combined Weight Matter Element Extension Model
by Shenggang Wang, Chao Yuan, Lianxin Li, Xiaowei Su and Chao Wang
Appl. Sci. 2024, 14(10), 4111; https://doi.org/10.3390/app14104111 - 12 May 2024
Cited by 4 | Viewed by 1845
Abstract
Roof falls in coal mine roadways are the main causes of many casualties, shutdowns and production plan delays. To understand the relationship between the influencing factors of roadway roof fall accidents and the importance ranking of the accidents, we will reduce safety accidents [...] Read more.
Roof falls in coal mine roadways are the main causes of many casualties, shutdowns and production plan delays. To understand the relationship between the influencing factors of roadway roof fall accidents and the importance ranking of the accidents, we will reduce safety accidents in coal mines. To enable the timely prediction and control of roadway roof fall risks, based on the investigation of many roadway roof fall risk factors, 12 evaluation indexes such as the roadway roof rock thickness, geological conditions and roadway section shape were selected. An evaluation index system of roadway roof fall risks is constructed. A risk degree standard of roadway roof falls is proposed. The risk evaluation model of roadway roof falls was established by using the combination weight of the analytic hierarchy process (AHP), entropy weight method (EW) and matter element extension theory. According to the principle of the maximum membership degree, the risk degree of roadway roof falls is determined. Based on Java Web, a risk assessment system for roadway roof falls was developed. We name the system Multiple Weight-Material Element Web (MW-MEW). The MW-MEW system was used to evaluate the risk degree of roof falls in the C9 return airway of the Xingu Coal Mine. Compared with the evaluation results of the AHP matter element extension model, it is found that the evaluation results of the MW-MEW system are more in line with the actual engineering conditions. The successful application of the MW-MEW system will provide new avenues for the quantitative evaluation of roof fall risks in coal mine roadways. Full article
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17 pages, 5054 KB  
Article
Planetary Energy Flow and Entropy Production Rate by Earth from 2002 to 2023
by Elijah Thimsen
Entropy 2024, 26(5), 350; https://doi.org/10.3390/e26050350 - 23 Apr 2024
Viewed by 4154
Abstract
In this work, satellite data from the Clouds and Earth’s Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are analyzed to determine how the global absorbed sunlight and global entropy production rates have changed from 2002 to 2023. The data [...] Read more.
In this work, satellite data from the Clouds and Earth’s Radiant Energy System (CERES) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are analyzed to determine how the global absorbed sunlight and global entropy production rates have changed from 2002 to 2023. The data is used to test hypotheses derived from the Maximum Power Principle (MPP) and Maximum Entropy Production Principle (MEP) about the evolution of Earth’s surface and atmosphere. The results indicate that both the rate of absorbed sunlight and global entropy production have increased over the last 20 years, which is consistent with the predictions of both hypotheses. Given the acceptance of the MPP or MEP, some peripheral extensions and nuances are discussed. Full article
(This article belongs to the Collection Disorder and Biological Physics)
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14 pages, 3715 KB  
Article
Synergy Prediction Model of Information Entropy Based on Zone Safety Degree and Stope Roof Weighting Step Analysis
by Lijun Xiong, Haiping Yuan, Hengzhe Li, Xiaohu Liu, Yangyao Zou, Shuaijie Ji and Xingye Fang
Axioms 2023, 12(9), 892; https://doi.org/10.3390/axioms12090892 - 19 Sep 2023
Cited by 3 | Viewed by 1565
Abstract
During the underground mining of coal resources, the rock pressure emerges acutely and the mine geological disasters occur frequently. It is of great significance to grasp the manifestation law of rock pressure in time to guide the safety production and operation in the [...] Read more.
During the underground mining of coal resources, the rock pressure emerges acutely and the mine geological disasters occur frequently. It is of great significance to grasp the manifestation law of rock pressure in time to guide the safety production and operation in the pit. In this research, the calculation equations and concept of information entropy based on zone safety degree are primarily defined, and the synergetic theory of the maximum information entropy principle is combined to put forward the synergy prediction model of information entropy based on zone safety degree. In the meantime, the synergy prediction model of information entropy based on zone safety degree is employed to calculate and predict the first weighting step and the periodic weighting step of the main roof of the 9203 working face of Hengsheng Coal Mine in China’s Shanxi Province, as well as verifying the validity and reliability of the synergy prediction model of information entropy based on zone safety degree by the comparison of similar simulation test results, which has presented a scientific basis for the effective control of rock pressure and roof management. Full article
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22 pages, 8057 KB  
Article
Research on Spatial Restructuring of Farmers’ Homestead Based on the “Point-Line-Surface” Characteristics of Mountain Villages
by Yingbin Feng, Jingjing Li and Dedong Feng
Land 2023, 12(8), 1598; https://doi.org/10.3390/land12081598 - 14 Aug 2023
Cited by 6 | Viewed by 2745
Abstract
The spatial restructuring of rural settlements is conducive to the realization of rural transition and development. This study constructed a “point-line-surface” framework for the spatial reconstruction of the homestead in a typical mountain village and used the weighted Voronoi diagram and buffer analysis [...] Read more.
The spatial restructuring of rural settlements is conducive to the realization of rural transition and development. This study constructed a “point-line-surface” framework for the spatial reconstruction of the homestead in a typical mountain village and used the weighted Voronoi diagram and buffer analysis method to analyze. The results are as follows. (1) The development capacity of rural homesteads in Longfeng Village was divided into three levels: high, medium, and low. Among them, the high-level homesteads clustered in the north and south of the village in the form of a “T” and a long strip, respectively; the medium-level homesteads are mostly aggregated in the middle of the village; the low-level homesteads are mainly distributed along the Fenghuang Mountain. (2) The layout of homesteads in Longfeng Village was axis-oriented, which is manifested by the number and scale being in a gradient-decreasing pattern with the main road axis as the centerline. (3) According to the principle of “maximum” development capacity of the homestead, nine reconstruction units are divided. By calculating the location entropy, it is found that the dominant functions of each reconstruction unit mainly include supporting life services, operational production, ecological agricultural production, and traditional agricultural production, and there are obvious differences in the development patterns of homesteads in different functional units. (4) Based on the “point-line-surface” characteristics of the homestead, four reconstruction modes, namely, modern community type, field and garden integration type, road-pointing type, and traditional residential type, are summarized, and the reconstruction strategies are proposed accordingly. The “point-line-surface” framework of rural settlements is of practical significance and theoretical value, which can provide a decision-making reference for the optimization and reorganization of residential land space in villages of the same type in mountain areas. Moreover, the integrated and innovative framework proposed in the paper has also international significance, thanks to the possibility of replicating the research strategy and methodological approach in other contexts. Full article
(This article belongs to the Special Issue Agricultural Land Use and Rural Development)
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23 pages, 1669 KB  
Article
Applying the Action Principle of Classical Mechanics to the Thermodynamics of the Troposphere
by Ivan R. Kennedy and Migdat Hodzic
Appl. Mech. 2023, 4(2), 729-751; https://doi.org/10.3390/applmech4020037 - 5 Jun 2023
Cited by 2 | Viewed by 4676
Abstract
Advances in applied mechanics have facilitated a better understanding of the recycling of heat and work in the troposphere. This goal is important to meet practical needs for better management of climate science. Achieving this objective may require the application of quantum principles [...] Read more.
Advances in applied mechanics have facilitated a better understanding of the recycling of heat and work in the troposphere. This goal is important to meet practical needs for better management of climate science. Achieving this objective may require the application of quantum principles in action mechanics, recently employed to analyze the reversible thermodynamics of Carnot’s heat engine cycle. The testable proposals suggested here seek to solve several problems including (i) the phenomena of decreasing temperature and molecular entropy but increasing Gibbs energy with altitude in the troposphere; (ii) a reversible system storing thermal energy to drive vortical wind flow in anticyclones while frictionally warming the Earth’s surface by heat release from turbulence; (iii) vortical generation of electrical power from translational momentum in airflow in wind farms; and (iv) vortical energy in the destructive power of tropical cyclones. The scalar property of molecular action (@t mvds, J-sec) is used to show how equilibrium temperatures are achieved from statistical equality of mechanical torques (mv2 or mr2ω2); these are exerted by Gibbs field quanta for each kind of gas phase molecule as rates of translational action (d@t/dt ≡mr2ω/dt ≡ mv2). These torques result from the impulsive density of resonant quantum or Gibbs fields with molecules, configuring the trajectories of gas molecules while balancing molecular pressure against the density of field energy (J/m3). Gibbs energy fields contain no resonant quanta at zero Kelvin, with this chemical potential diminishing in magnitude as the translational action of vapor molecules and quantum field energy content increases with temperature. These cases distinguish symmetrically between causal fields of impulsive quanta (Σhν) that energize the action of matter and the resultant kinetic torques of molecular mechanics (mv2). The quanta of these different fields display mean wavelengths from 10−4 m to 1012 m, with radial mechanical advantages many orders of magnitude greater than the corresponding translational actions, though with mean quantum frequencies (v) similar to those of radial Brownian movement for independent particles (ω). Widespread neglect of the Gibbs field energy component of natural systems may be preventing advances in tropospheric mechanics. A better understanding of these vortical Gibbs energy fields as thermodynamically reversible reservoirs for heat can help optimize work processes on Earth, delaying the achievement of maximum entropy production from short-wave solar radiation being converted to outgoing long-wave radiation to space. This understanding may improve strategies for management of global changes in climate. Full article
(This article belongs to the Special Issue Applied Thermodynamics: Modern Developments (2nd Volume))
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21 pages, 2620 KB  
Article
Self-Organization of Enzyme-Catalyzed Reactions Studied by the Maximum Entropy Production Principle
by Andrej Dobovišek, Marko Vitas, Tina Blaževič, Rene Markovič, Marko Marhl and Aleš Fajmut
Int. J. Mol. Sci. 2023, 24(10), 8734; https://doi.org/10.3390/ijms24108734 - 13 May 2023
Cited by 2 | Viewed by 3236
Abstract
The self-organization of open reaction systems is closely related to specific mechanisms that allow the export of internally generated entropy from systems to their environment. According to the second law of thermodynamics, systems with effective entropy export to the environment are better internally [...] Read more.
The self-organization of open reaction systems is closely related to specific mechanisms that allow the export of internally generated entropy from systems to their environment. According to the second law of thermodynamics, systems with effective entropy export to the environment are better internally organized. Therefore, they are in thermodynamic states with low entropy. In this context, we study how self-organization in enzymatic reactions depends on their kinetic reaction mechanisms. Enzymatic reactions in an open system are considered to operate in a non-equilibrium steady state, which is achieved by satisfying the principle of maximum entropy production (MEPP). The latter is a general theoretical framework for our theoretical analysis. Detailed theoretical studies and comparisons of the linear irreversible kinetic schemes of an enzyme reaction in two and three states are performed. In both cases, in the optimal and statistically most probable thermodynamic steady state, a diffusion-limited flux is predicted by MEPP. Several thermodynamic quantities and enzymatic kinetic parameters, such as the entropy production rate, the Shannon information entropy, reaction stability, sensitivity, and specificity constants, are predicted. Our results show that the optimal enzyme performance may strongly depend on the number of reaction steps when linear reaction mechanisms are considered. Simple reaction mechanisms with a smaller number of intermediate reaction steps could be better organized internally and could allow fast and stable catalysis. These could be features of the evolutionary mechanisms of highly specialized enzymes. Full article
(This article belongs to the Special Issue Molecular Advances in Enzyme Kinetics)
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18 pages, 6988 KB  
Article
Analysis of Inner Flow in a Multi-Stage Double-Suction Centrifugal Pump Using the Detached Eddy Simulation Method
by Wenjie Peng, Ji Pei, Shouqi Yuan, Jiabin Wang, Benying Zhang, Wenjie Wang and Jiaxing Lu
Processes 2023, 11(4), 1026; https://doi.org/10.3390/pr11041026 - 28 Mar 2023
Cited by 7 | Viewed by 3034
Abstract
In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity [...] Read more.
In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity field distribution characteristics and pressure fluctuation propagation law using the detached eddy simulation method was conducted. Additionally, the principle of entropy generation was put to use to quantify and compare the energy loss of different components. The results reveal that the existence of unstable flow structures in the first-stage impeller and a large number of vortical structures in the back-channel result in reduced operational efficiency of the pump. Furthermore, the pressure fluctuation intensity reaches its maximum with 0.15 at the blade trailing edge, which propagates to the tongue region of the forward flow channel and the double-volute under the low rates condition. Additionally, the main frequency of the monitoring points in the inter-stage flow channel and volute is basically located at a frequency of 198.667 Hz, which is twice the blade frequency. Consequently, the wall entropy production accounting for nearly 25% cannot be ignored and that the loss mainly occurs in the double-volute and the inter-stage flow channel due to the occurrence of irregular flow in the above components with more than 50%. The outcomes of this research present a valuable point of reference for the optimization of structural design in multistage turbomachines with various applications. Full article
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