Dynamical Theory Research Articles

Analysis of the dynamic performance of pantograph-catenary system with posture of pan-head

Abstract This article focuses on the changes in the contact pressure between the pantograph and the catenary caused by variations in the pan-head posture. Starting from the kinematics and dynamics of the pantograph and based on the theories of multibody dynamics and finite element analysis, the pantograph head model is validated, and a pantograph rigid-flexible coupling model considering the flexibility of the pantograph head is established. A coupling model between the pantograph model and the rigid contact catenary is established to extract the pantograph posture and dynamic performance data during operation. By finely considering and modeling the structural characteristic parameters of the pantograph, the influence of different pantograph head characteristic parameters on the dynamic performance of the catenary system is studied. This provides a research basis for understanding the degree of influence of different characteristic parameters on the catenary dynamics.

Climatic temperature and precipitation jointly influence body size in species of western rattlesnakes.

Both the metabolic theory of ecology and dynamic energy budget theory predict that climate influences body size through its effects on first-order determinants of energetics: reactive temperatures, carbon resources and oxygen availability. Although oxygen is seldom limiting in terrestrial systems, temperature and resources vary spatially. We used redundancy analyses and variation partitioning to evaluate the influence of climatic temperature, precipitation and their seasonalities on multivariate body size across the distributions of four species of the western rattlesnake group in North America (Crotalus pyrrhus, C. scutulatus, C. oreganus and C. viridis). Most species showed a pattern of increased body size in cooler, mesic climates and decreased body size in warmer, xeric climates. Exceptions to the pattern provided additional context through climatic idiosyncrasies in the distributions of each species. For example, the general pattern of a negative influence of temperature on body size was not apparent for C. oreganus, which ranges across the mildest climates overall among the four species. In contrast to previous studies, we found that seasonality had negligible effects on body size. We suggest that precipitation gradients correlate positively with resource availability in driving intraspecific body size and that temperature compounds this gradient by increasing baseline metabolic demands and restricting activity in particularly warm or otherwise extreme climates.

Orchestrated Stakeholder Dialogue: Place in Dynamic Capability Theory and Strategic Significance

Orchestrated Stakeholder Dialogue: Place in Dynamic Capability Theory and Strategic Significance

Enhanced cellular longevity arising from environmental fluctuations

Cellular longevity is regulated by both genetic and environmental factors. However, the interactions of these factors in the context of aging remain largely unclear. Here, we formulate a mathematical model for dynamic glucose modulation of a core gene circuit in yeast aging, which not only guided the design of pro-longevity interventions but also revealed the theoretical principles underlying these interventions. We introduce the dynamical systems theory to capture two general means for promoting longevity-the creation of a stable fixed point in the "healthy" state of the cell and the "dynamic stabilization" of the system around this healthy state through environmental oscillations. Guided by the model, we investigate how both of these can be experimentally realized by dynamically modulating environmental glucose levels. The results establish a paradigm for theoretically analyzing the trajectories and perturbations of aging that can be generalized to aging processes in diverse cell types and organisms.

Digitalization and productivity in the Chinese wind power industry: the serial mediating role of reconfiguration capability and technological innovation

PurposeWind power is the most promising renewable energy source in China. The development of digital technologies has brought about unprecedented growth opportunities and prospects for wind power. However, the relationship between digital technology adoption and total factor productivity (TFP) in the wind power industry in China has not been empirically assessed. This study aims to clarify whether and how digital technology adoption affects the TFP of the wind power industry in China.Design/methodology/approachBased on the data of listed companies in the Chinese wind power industry from 2006 to 2021, this study proposes and verifies relevant hypotheses with two-way fixed effects regression models.FindingsThe empirical results indicate that digital technology adoption is the cornerstone of the TFP of China’s wind power industry. Reconfiguration capability and technological innovation serially mediate the above relationship. In addition, the incentive effect of digital technology adoption varies among wind power firms. The impact of digital technology adoption is more significant in firms that are old and located in economically undeveloped regions.Originality/valueThis study is one of the earliest attempts to investigate the relationship between digital technology adoption and TFP in the renewable energy sectors of emerging economies. By integrating dynamic capability theory and the analytical framework of “Capability-Behavior-Performance” into the digital context, this study offers the theoretical insights into how digital technology adoption can enhance organizational reconfiguration capability, thereby stimulating technological innovation and subsequent TFP. Additionally, the impacts of different digital technologies are estimated in entirety, rather than in isolation.

Influence of anti-ferromagnetic ordering and electron correlation on the electronic structure of MnTiO3

Electron correlation and long-range magnetic ordering have a significant impact on the electronic structure and physical properties of solids. Here, we investigate the electronic structure of ilmenite MnTiO3 using room temperature photoemission spectroscopy and theoretical approaches within density functional theory (DFT), DFT+ U and DFT+dynamical mean-field theory (DMFT). Mn 2p (Ti 2p) core level photoemission spectra, confirming Mn2+ (Ti4+) oxidation state, exhibit multiple satellites which are very similar to that of MnO (TiO2), suggesting similar strength of various interactions in this system. Valence band spectra collected at different photon energies suggest dominant Mn 3d character in the highest occupied band with a wide insulating gap. DFT(+ U) correctly predicts the experimentally observed anti-ferromagnetic (AFM) insulating ground state for MnTiO3 where the requirement of a large U to reproduce the experimental values of magnetic moment and band gap signifies the importance of electron correlation. Magnetically disordered paramagnetic (PM) phase could be well captured within DFT+DMFT, which provides an excellent agreement for the experimental band gap, paramagnetic moment, valence band spectra as well as dominant Mn 3d character in the highest occupied band. The calculated spectral function remains largely unaffected and exhibits sharper features in the magnetically ordered AFM phase. We show that the electronic structure of MnTiO3 in both the PM and AFM phases can be accurately described within DFT+DMFT.

Research on non-linear dynamic simulation model of feeding system

Abstract The automatic gun feeding system is an important mechanism for achieving continuous shooting, but due to its complex structure, there is a lot of contact during firing, and its reliability is lower. To improve the reliability of the feeding system and its dynamic characteristics, a multi rigid body dynamic simulation model of the feeding system considering contact nonlinearity was established based on nonlinear dynamics theory. The dynamic characteristics of the feeding system were analyzed for single and continuous firing. The research results indicate that the presence of contact nonlinearity increases the interaction forces between components and also increases the uncertainty of component motion.

Realization of a shock-tube facility to study the Richtmyer-Meshkov instability driven by a strong shock wave.

A shock-tube facility capable of generating a planar shock with the Mach number higher than 3.0 is developed for studying Richtmyer-Meshkov instability induced by a strong shock wave (referred to as strong-shock RMI). Shock enhancement is realized through the convergence of shock within a channel with the profile determined by using shock dynamics theory. The facility is designed considering the repeatability of shock generation, transition of shock profile, and effects of viscosity and flow choking. By measuring the dynamic pressure of the tube flow using pressure sensors and capturing the shock movement through the high-speed shadowing technique, the reliability and repeatability of the shock tube for generating a strong planar shock are first verified. Particular emphasis is then placed on the ability of the facility to study strong-shock RMI, for which a thin polyester film is adopted to form the initial interface separating gases of different densities. The results indicate that the shock tube is reliable for conducting strong-shock RMI experiments.

Single-site DFT+DMFT for vanadium dioxide using bond-centered orbitals

We present a combined density-functional theory and single-site dynamical mean-field theory (DMFT) study of vanadium dioxide (VO2) using an unconventional set of bond-centered orbitals as the basis of the correlated subspace. VO2 is a prototypical material undergoing a metal-insulator transition (MIT), hosting both intriguing physical phenomena and the potential for industrial applications. With our choice of correlated subspace basis, we investigate the interplay of structural dimerization and electronic correlations in VO2 in a computationally cheaper way compared to other state-of-the-art methods, such as cluster DMFT. Our approach allows us to treat the rutile and M1 monoclinic VO2 phases on an equal footing and to vary the dimerizing distortion continuously, exploring the energetics of the transition between the two phases. The choice of basis presented in this work hence offers a complementary view on the long-standing discussion of the MIT in VO2 and suggests possible future extensions to other similar materials hosting molecular-orbital-like states. Published by the American Physical Society 2024

Statistical Dynamics and Subgrid Modelling of Turbulence: From Isotropic to Inhomogeneous

Turbulence is the most important, ubiquitous, and difficult problem of classical physics. Feynman viewed it as essentially unsolved, without a rigorous mathematical basis to describe the statistical dynamics of this most complex of fluid motion. However, the paradigm shift came in 1959, with the formulation of the Eulerian direct interaction approximation (DIA) closure by Kraichnan. It was based on renormalized perturbation theory, like quantum electrodynamics, and is a bare vertex theory that is manifestly realizable. Here, we review some of the subsequent exciting achievements in closure theory and subgrid modelling. We also document in some detail the progress that has been made in extending statistical dynamical turbulence theory to the real world of interactions with mean flows, waves and inhomogeneities such as topography. This includes numerically efficient inhomogeneous closures, like the realizable quasi-diagonal direct interaction approximation (QDIA), and even more efficient Markovian Inhomogeneous Closures (MICs). Recent developments include the formulation and testing of an eddy-damped Markovian anisotropic closure (EDMAC) that is realizable in interactions with transient waves but is as efficient as the eddy-damped quasi-normal Markovian (EDQNM). As a similarly efficient closure, the realizable eddy-damped Markovian inhomogeneous closure (EDMIC) has been developed. Moreover, we present subgrid models that cater for the complex interactions that occur in geophysical flows. Recent progress includes the determination of complete sets of subgrid terms for skilful large-eddy simulations of baroclinic inhomogeneous turbulent atmospheric and oceanic flows interacting with Rossby waves and topography. The success of these inhomogeneous closures has also led to further applications in data assimilation and ensemble prediction and generalization to quantum fields.

Knowledge entrepreneurship in higher education institutions: a perspective of knowledge sharing and entrepreneurial leadership in Pakistani HEIs

PurposeThe purpose of this study is to contribute to the research of knowledge management in higher education institutions (HEIs) by studying the enablers of knowledge entrepreneurship. Anchored in the dynamic capability theory, knowledge entrepreneurship is heterogeneously distributed in HEIs and is critical for the sustenance of organizations in the knowledge economy. This aim is realized by understanding the determinants of knowledge entrepreneurship and empirically investigating the relationship of knowledge-sharing behaviour and entrepreneurial leadership with knowledge entrepreneurship.Design/methodology/approachData was collected through structured questionnaires from 550 faculty members of HEIs in Pakistan by adequately representing the sample size through regional stratification and proportionate sampling. Data was analyzed through the Analysis of Moment Structures software where the data validation and reliability were achieved using correlations, confirmatory factor analysis and structured equation modelling to generate generalizable results.FindingsThe findings revealed that knowledge sharing is an important component in developing knowledge entrepreneurship. Entrepreneurial leadership is pivotal in providing the support, vision and autonomy to individuals with personal and professional capabilities to ensure the creation of new knowledge, collaboration and innovation.Research limitations/implicationsThe study contributes to an understanding of relationship of knowledge sharing and entrepreneurial leadership that leads to promotion of knowledge entrepreneurship in HEIs of Pakistan. In addition, the findings of the study extend the existing literature on knowledge entrepreneurship by offering the positive mediating role of entrepreneurial leadership in the universities of Pakistan, hence, addressing the specific challenges and opportunities faced by the HEIs of a developing country like Pakistan. The theoretical framework of the study elucidates the importance of knowledge sharing and entrepreneurial leadership by using the dynamic capabilities theory and extends the scope of the aforementioned theory in entrepreneurial leadership realm.Practical implicationsBy generating an understanding of the dynamics of knowledge entrepreneurship this study tries to help policymakers and educational leaders to develop strategies to cultivate a culture of knowledge sharing and entrepreneurial leadership in Pakistani HEIs. Building the entrepreneurial ecosystem entails prioritizing knowledge creation, knowledge sharing and retention that can lead to innovative solutions for local and global challenges.Originality/valueThe study used dynamic capabilities theory to link the knowledge and resources together for the education sector for sustainable outcomes in the knowledge economy. To the best of the authors’ knowledge, this is the first study to empirically study the behaviour of HEIs to create and support knowledge entrepreneurship in the presence of entrepreneurial leadership in the context of a developing country, Pakistan. Becoming a knowledge-based society will help Pakistan upgrade itself to the list of developed countries.

High accuracy solutions for the Pochhammer–Chree equation in elastic media

This study investigates the nonlinear Pochhammer–Chree equation, a model crucial for understanding wave propagation in elastic rods, through the application of the Khater III method. The research aims to derive precise analytical solutions and validate them using He’s variational iteration method (VIM). The Pochhammer–Chree equation’s relationship to other nonlinear evolution equations, such as the Korteweg-de Vries and nonlinear Schrödinger equations, underscores its significance in the field of nonlinear wave dynamics. The methodology employs the Khater III method for deriving analytical solutions, while He’s VIM serves as a numerical validation tool, ensuring the accuracy and stability of the obtained results. This dual approach not only yields novel solutions but also provides a robust framework for analyzing complex wave phenomena in elastic media. The findings of this study have significant implications for material science and engineering applications, offering new insights into the behavior of waves in elastic rods. By bridging the gap between theoretical models and practical applications, this research contributes to the advancement of both mathematical theory and physical understanding of nonlinear wave dynamics. Situated within the domain of applied mathematics, with a focus on nonlinear wave equations, this work exemplifies the interdisciplinary nature of contemporary research in mathematical physics. The results presented herein open new avenues for future investigations in related fields and highlight the potential for innovative applications in material science and engineering.

Exploring the Impacts of Green Supply Chain Integration and Ambidextrous Green Innovation on the Financial Performance of China’s Pharmaceutical Manufacturing Enterprises

This study focuses on the factors affecting the financial performance of pharmaceutical manufacturing enterprises. Based on dynamic capability theory and ambidextrous innovation theory, this study adopts the Resource–Behavior–Performance framework to investigate how green supply chain integration (GSCI) and ambidextrous green innovation affect financial performance. The proposed hypotheses were tested through structural equation modeling using data from 400 China’s pharmaceutical manufacturing enterprises. The results indicate that the various dimensions of GSCI and ambidextrous green innovation yield distinct outcomes. Among the three dimensions of GSCI, only green supplier integration and green customer integration significantly impact financial performance directly, unlike green internal integration. Among the two dimensions of ambidextrous green innovation, only exploitative green innovation significantly influences financial performance, acting as a mediator between the GSCI dimensions and financial performance, while exploratory green innovation does not. The main advantages of this study include considering the connotation and value of GSCI from a green dynamic capability perspective, as well as the effects of exploratory and exploitative green innovation as intermediary behaviors while simultaneously considering the performance effects of GSCI and ambidextrous green innovation. This study offers novel academic insights and practical guidelines for pharmaceutical manufacturing enterprises to integrate GSCI and ambidextrous green innovation, with the aim of achieving better financial performance in their sustainable development efforts.

RESEARCH ON THE MECHANISM OF RESILIENT LEADERSHIP'S EFFECT ON THE RESILIENCE OF SMALL TOURISM ENTERPRISES

Tourism, as a strategic pillar industry in our country, is critical in promoting economic development and labor employment. During the "Fourteenth Five-Year Plan" period, China will fully enter the era of mass tourism. This study focuses specifically on small tourism enterprises. Based on a review of the resilience of domestic and foreign enterprises, guided by relevant theories such as dynamic capability theory and resource allocation theory, and on the basis of redefining the concept connotation and extension of small tourism enterprises' resilience, tenacious leadership, inter-organizational learning, resource restructuring and environmental complexity, This paper builds a theoretical model based on the influence mechanism of resilient leadership and resilience of small tourism enterprises, describes and statistically analyzes the basic characteristics, current situation and existing problems of resilience of small tourism enterprises, and uses case analysis and empirical analysis methods to explore the impact degree and impact path of resilient leadership on resilience of small tourism enterprises. Finally, the study proposes measures to boost the resilience of small tourism enterprises, drawing from the findings of case and empirical analysis.

Impact of Artificial Intelligence on Supply Chain Efficiency in Turkey

Purpose: The aim of the study was to evaluate the impact of artificial intelligence on supply chain efficiency in Turkey. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Artificial intelligence (AI) has significantly enhanced supply chain efficiency in Turkey. AI applications such as predictive analytics, demand forecasting, and optimization algorithms have streamlined operations, reduced costs, and improved decision-making. Automation of repetitive tasks through AI has increased productivity and accuracy in inventory management and logistics. Unique Contribution to Theory, Practice and Policy: Resource-based view (RBV) theory, dynamic capabilities theory & technology acceptance model (TAM) may be used to anchor future studies on the impact of artificial intelligence on supply chain efficiency in Turkey. Invest in continuous training and development programs for supply chain professionals to effectively utilize AI tools. Develop industry standards and regulatory frameworks for the ethical use of AI in supply chains. These policies should address data privacy, security, and the responsible use of AI technologies to protect stakeholders.

A network control theory pipeline for studying the dynamics of the structural connectome.

Network control theory (NCT) is a simple and powerful tool for studying how network topology informs and constrains the dynamics of a system. Compared to other structure-function coupling approaches, the strength of NCT lies in its capacity to predict the patterns of external control signals that may alter the dynamics of a system in a desired way. An interesting development for NCT in the neuroscience field is its application to study behavior and mental health symptoms. To date, NCT has been validated to study different aspects of the human structural connectome. NCT outputs can be monitored throughout developmental stages to study the effects of connectome topology on neural dynamics and, separately, to test the coherence of empirical datasets with brain function and stimulation. Here, we provide a comprehensive pipeline for applying NCT to structural connectomes by following two procedures. The main procedure focuses on computing the control energy associated with the transitions between specific neural activity states. The second procedure focuses on computing average controllability, which indexes nodes' general capacity to control the dynamics of the system. We provide recommendations for comparing NCT outputs against null network models, and we further support this approach with a Python-based software package called 'network control theory for python'. The procedures in this protocol are appropriate for users with a background in network neuroscience and experience in dynamical systems theory.

Very Strong Hydrogen Bond in Nitrophthalic Cocrystals.

This work presents the studies of a very strong hydrogen bond (VSHB) in biologically active phthalic acids. Research on VSHB comes topical due to its participation in many biological processes. The studies cover the modelling of intermolecular interactions and phthalic acids with 2,4,6-collidine and N,N-dimethyl-4-pyridinamine complexes with aim to obtain a VSHB. The four synthesized complexes were studied by experimental X-ray, IR, and Raman methods, as well as theoretical Car-Parrinello Molecular Dynamics (CP-MD) and Density Functional Theory (DFT) simulations. By variation of the steric repulsion and basicity of the complex' components, a very short intramolecular hydrogen bond was achieved. The potential energy curves calculated by the DFT method were characterized by a low barrier (0.7 and 0.9 kcal/mol) on proton transfer in the OHN intermolecular hydrogen bond for 3-nitrophthalic acid with either 2,4,6-collidine or N,N-dimethyl-4-pyridinamine cocrystals. Moreover, the CP-MD simulations exposed very strong bridging proton dynamics in the intermolecular hydrogen bonds. The accomplished crystallographic and spectroscopic studies indicate that the OHO intramolecular hydrogen bond in 4-nitrophthalic cocrystals is VSHB. The influence of a strong steric effect on the geometry of the studied cocrystals and the stretching vibration bands of the carboxyl and carboxylate groups was elaborated.

Deformation theory and nonlinear dynamic behavior of PVC gel actuators

Polyvinyl chloride (PVC) gel generates complex nonlinear vibration behavior under an alternating current voltage excitation, which has potential application as a dynamic electromechanical actuator. However, there are few studies on the deformation theory of PVC gel actuators, especially the dynamic nonlinear response theory. In this paper, a complex dynamic model is established according to the electrodeformation mechanism of PVC film, and the nonlinear dynamic behavior of the actuator is numerically studied by a differential equation. The effects of applied voltage amplitude, voltage frequency, dibutyl adipate content, mechanical tension, and bias voltage on the dynamic properties of PVC film were analyzed under the condition of equal biaxial tension. The variation of amplitude and the generation and disappearance of the beat frequency during vibration are analyzed by using time-domain characteristics. The degree of PVC actuator nonlinearity as well as vibration stability and periodicity is also reflected based on the phase path and Poincare map. Finally, the law of influence of external condition parameters on the dynamic response of the PVC actuator is obtained.

Enterprise value creation effects of artificial intelligence technology from the perspective of digital agility: evidence from China

ABSTRACT As a pivotal technology driving the latest wave of technological revolution and industry transformation, artificial intelligence (AI) is permeating the processes of business operations widely. Grounded in the dynamic capability theory, the research use Word2Vec and Python to extract metrics for AI technology from annual reports of Chinese A-share listed companies from 2012 to 2022. This research empirically investigates the impact of AI technology on the level of enterprise value creation. The findings reveal that the application of AI technology by listed companies significantly enhances their value creation, a conclusion that remains robust following various endogeneity and robustness tests. AI technology empowers enterprise value creation through the mechanisms of sensing, integrating, and restructuring digital agility. Furthermore, the value-creation effect of AI technology is more significant in manufacturing and the eastern region. The results elucidate the logic behind the influence of AI technology on enterprise value creation and provide practical support for organisations in implementing AI strategic planning and decision-making.

A Discrete Hamilton–Jacobi Theory for Contact Hamiltonian Dynamics

In this paper, we propose a discrete Hamilton–Jacobi theory for (discrete) Hamiltonian dynamics defined on a (discrete) contact manifold. To this end, we first provide a novel geometric Hamilton–Jacobi theory for continuous contact Hamiltonian dynamics. Then, rooting on the discrete contact Lagrangian formulation, we obtain the discrete equations for Hamiltonian dynamics by the discrete Legendre transformation. Based on the discrete contact Hamilton equation, we construct a discrete Hamilton–Jacobi equation for contact Hamiltonian dynamics. We show how the discrete Hamilton–Jacobi equation is related to the continuous Hamilton–Jacobi theory presented in this work. Then, we propose geometric foundations of the discrete Hamilton–Jacobi equations on contact manifolds in terms of discrete contact flows. At the end of the paper, we provide a numerical example to test the theory.