Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Article Types

Countries / Regions

Search Results (126)

Search Parameters:
Keywords = system dichotomy

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
12 pages, 10018 KiB  
Article
Unraveling the Compound Eye Design of the Diurnal Moth Histia flabellicornis (Lepidoptera: Zygaenidae)
by Qing-Xiao Chen, Ya-Fei Li and Yun-Zhu Huo
Insects 2025, 16(8), 771; https://doi.org/10.3390/insects16080771 - 27 Jul 2025
Viewed by 383
Abstract
Lepidoptera typically exhibit a dichotomy in compound eye design: diurnal butterflies possess apposition eyes for high resolution in bright light, whereas nocturnal moths have superposition eyes for enhanced sensitivity under dim conditions. However, exceptions, particularly among diurnal moths, challenge this pattern and offer [...] Read more.
Lepidoptera typically exhibit a dichotomy in compound eye design: diurnal butterflies possess apposition eyes for high resolution in bright light, whereas nocturnal moths have superposition eyes for enhanced sensitivity under dim conditions. However, exceptions, particularly among diurnal moths, challenge this pattern and offer insights into the evolution of compound eyes in Lepidoptera. In this study, we investigated the compound eye design of the diurnal moth Histia flabellicornis (Fabricius) using light, scanning, and transmission electron microscopy to determine whether it has superposition or apposition eyes, and to quantitatively analyze the structural features and visual acuity. Our results reveal that H. flabellicornis possesses apposition-type compound eyes composed of over 2000 ommatidia, each comprising a cornea, a crystalline cone, nine retinula cells forming a fused rhabdom, and a few isolated tracheoles. The calculated interommatidial angles (Δϕ = 4.08°) and the eye parameter P (P = 1.74) suggest a visual system adapted to moderate light conditions, balancing spatial resolution with photon capture. These findings confirm the presence of apposition eyes in H. flabellicornis, supporting the moth’s adaptation to diurnal behavior and contributing to understanding the evolutionary diversification of compound eye designs in Lepidoptera. Full article
(This article belongs to the Section Insect Physiology, Reproduction and Development)
Show Figures

Figure 1

32 pages, 7150 KiB  
Article
A Riemannian Dichotomizer Approach on Symmetric Positive Definite Manifolds for Offline, Writer-Independent Signature Verification
by Nikolaos Vasilakis, Christos Chorianopoulos and Elias N. Zois
Appl. Sci. 2025, 15(13), 7015; https://doi.org/10.3390/app15137015 - 21 Jun 2025
Cited by 1 | Viewed by 381
Abstract
Automated handwritten signature verification continues to pose significant challenges. A common approach for developing writer-independent signature verifiers involves the use of a dichotomizer, a function that generates a dissimilarity vector with the differences between similar and dissimilar pairs of signature descriptors as components. [...] Read more.
Automated handwritten signature verification continues to pose significant challenges. A common approach for developing writer-independent signature verifiers involves the use of a dichotomizer, a function that generates a dissimilarity vector with the differences between similar and dissimilar pairs of signature descriptors as components. The Dichotomy Transform was applied within a Euclidean or vector space context, where vectored representations of handwritten signatures were embedded in and conformed to Euclidean geometry. Recent advances in computer vision indicate that image representations to the Riemannian Symmetric Positive Definite (SPD) manifolds outperform vector space representations. In offline signature verification, both writer-dependent and writer-independent systems have recently begun leveraging Riemannian frameworks in the space of SPD matrices, demonstrating notable success. This work introduces, for the first time in the signature verification literature, a Riemannian dichotomizer employing Riemannian dissimilarity vectors (RDVs). The proposed framework explores a number of local and global (or common pole) topologies, as well as simple serial and parallel fusion strategies for RDVs for constructing robust models. Experiments were conducted on five popular signature datasets of Western and Asian origin, using blind intra- and cross-lingual experimental protocols. The results indicate the discriminative capabilities of the proposed Riemannian dichotomizer framework, which can be compared to other state-of-the-art and computationally demanding architectures. Full article
Show Figures

Figure 1

24 pages, 4791 KiB  
Article
Zircon out, Elpidite in: Deformation-Driven Zirconosilicate Evolution in Peralkaline Granites: A Case Study of the Papanduva Pluton (Brazil)
by Larissa P. Grangeiro, Frederico C. J. Vilalva, Silvio R. F. Vlach and Armando L. S. de Oliveira
Minerals 2025, 15(7), 667; https://doi.org/10.3390/min15070667 - 20 Jun 2025
Viewed by 253
Abstract
The peralkaline granites of the Papanduva Pluton (South Brazil) display a remarkable facies dichotomy, with zircon dominant in massive facies and diverse zirconosilicates (Zr-Si) in foliated facies. This study employs petrography and mineral chemistry (major and trace elements) to elucidate the textural diversity [...] Read more.
The peralkaline granites of the Papanduva Pluton (South Brazil) display a remarkable facies dichotomy, with zircon dominant in massive facies and diverse zirconosilicates (Zr-Si) in foliated facies. This study employs petrography and mineral chemistry (major and trace elements) to elucidate the textural diversity and compositional evolution of these minerals. Three discrete zirconosilicate groups were identified: Na-rich elpidite (euhedral, vein-like, and granular varieties), Na-poor (Na,K)Zr-Si-I, and silica-rich (Na,K)Zr-Si-II. Contrary to the expected crystallization sequences, trace element data reveal that REE enrichment correlates with deformation intensity rather than paragenetic order, with vein-like aggregates along deformation features showing the highest REE concentrations. Statistical analysis demonstrates significant correlations between REE contents and alkali exchange patterns. We propose a three-stage evolutionary model involving magmatic crystallization, deformation-enhanced fluid interaction, and late-stage recrystallization, with a progressive evolution from Na-dominated to K-dominated conditions. This study provides new insights into closed-system fluid evolution in agpaitic environments and highlights deformation as a primary control on element mobility in peralkaline granitic systems. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
Show Figures

Figure 1

42 pages, 551 KiB  
Article
AI Reasoning in Deep Learning Era: From Symbolic AI to Neural–Symbolic AI
by Baoyu Liang, Yuchen Wang and Chao Tong
Mathematics 2025, 13(11), 1707; https://doi.org/10.3390/math13111707 - 23 May 2025
Viewed by 5985
Abstract
The pursuit of Artificial General Intelligence (AGI) demands AI systems that not only perceive but also reason in a human-like manner. While symbolic systems pioneered early breakthroughs in logic-based reasoning, such as MYCIN and DENDRAL, they suffered from brittleness and poor scalability. Conversely, [...] Read more.
The pursuit of Artificial General Intelligence (AGI) demands AI systems that not only perceive but also reason in a human-like manner. While symbolic systems pioneered early breakthroughs in logic-based reasoning, such as MYCIN and DENDRAL, they suffered from brittleness and poor scalability. Conversely, modern deep learning architectures have achieved remarkable success in perception tasks, yet continue to fall short in interpretable and structured reasoning. This dichotomy has motivated growing interest in Neural–Symbolic AI, a paradigm that integrates symbolic logic with neural computation to unify reasoning and learning. This survey provides a comprehensive and technically grounded overview of AI reasoning in the deep learning era, with a particular focus on Neural–Symbolic AI. Beyond a historical narrative, we introduce a formal definition of AI reasoning and propose a novel three-dimensional taxonomy that organizes reasoning paradigms by representation form, task structure, and application context. We then systematically review recent advances—including Differentiable Logic Programming, abductive learning, program induction, logic-aware Transformers, and LLM-based symbolic planning—highlighting their technical mechanisms, capabilities, and limitations. In contrast to prior surveys, this work bridges symbolic logic, neural computation, and emergent generative reasoning, offering a unified framework to understand and compare diverse approaches. We conclude by identifying key open challenges such as symbolic–continuous alignment, dynamic rule learning, and unified architectures, and we aim to provide a conceptual foundation for future developments in general-purpose reasoning systems. Full article
18 pages, 6646 KiB  
Communication
An Ultra-Low-Power High-Precision Temperature Sensor Using Nonlinear Calibration with an Inaccuracy of +0.6/−1 °C from −30 °C to 90 °C for RFID Applications
by Hanyang Wang, Zhonghan Shen and Hao Min
Sensors 2025, 25(9), 2911; https://doi.org/10.3390/s25092911 - 4 May 2025
Viewed by 689
Abstract
This paper proposes a three-point nonlinear calibration scheme for an ultra-low-power, high-precision temperature sensor to address the issue where the temperature error of a 0.8 μW sensor exceeds ±1 °C in RFID (Radio-Frequency Identification) temperature measurement systems. The proposed calibration scheme introduces a [...] Read more.
This paper proposes a three-point nonlinear calibration scheme for an ultra-low-power, high-precision temperature sensor to address the issue where the temperature error of a 0.8 μW sensor exceeds ±1 °C in RFID (Radio-Frequency Identification) temperature measurement systems. The proposed calibration scheme introduces a temperature-dependent nonlinearity coefficient to the traditional linear calibration, effectively compensating for the sensor’s nonlinear output characteristics. To minimize calibration costs, a scheme embedding the calibration algorithm into the reader is proposed, along with a dichotomy-based approach for efficient temperature calibration. The experimental results demonstrate that, within the temperature range of −30 °C to 90 °C, the temperature error of five sensor samples can be reduced from ±8 °C to between −1 °C and 0.6 °C. This solution has been successfully implemented in mass production. Full article
(This article belongs to the Special Issue Sensors for High Temperature Monitoring)
Show Figures

Figure 1

23 pages, 1033 KiB  
Review
Memory T Cells in Respiratory Virus Infections: Protective Potential and Persistent Vulnerabilities
by Henry Sutanto, Febrian Ramadhan Pradana, Galih Januar Adytia, Bagus Aditya Ansharullah, Alief Waitupu, Bramantono Bramantono and Deasy Fetarayani
Med. Sci. 2025, 13(2), 48; https://doi.org/10.3390/medsci13020048 - 29 Apr 2025
Viewed by 1251
Abstract
Respiratory virus infections, such as those caused by influenza viruses, respiratory syncytial virus (RSV), and coronaviruses, pose a significant global health burden. While the immune system’s adaptive components, including memory T cells, are critical for recognizing and combating these pathogens, recurrent infections and [...] Read more.
Respiratory virus infections, such as those caused by influenza viruses, respiratory syncytial virus (RSV), and coronaviruses, pose a significant global health burden. While the immune system’s adaptive components, including memory T cells, are critical for recognizing and combating these pathogens, recurrent infections and variable disease outcomes persist. Memory T cells are a key element of long-term immunity, capable of responding swiftly upon re-exposure to pathogens. They play diverse roles, including cross-reactivity to conserved viral epitopes and modulation of inflammatory responses. However, the protective efficacy of these cells is influenced by several factors, including viral evolution, host age, and immune system dynamics. This review explores the dichotomy of memory T cells in respiratory virus infections: their potential to confer robust protection and the limitations that allow for breakthrough infections. Understanding the underlying mechanisms governing the formation, maintenance, and functional deployment of memory T cells in respiratory mucosa is critical for improving immunological interventions. We highlight recent advances in vaccine strategies aimed at bolstering T cell-mediated immunity and discuss the challenges posed by viral immune evasion. Addressing these gaps in knowledge is pivotal for designing effective therapeutics and vaccines to mitigate the global burden of respiratory viruses. Full article
(This article belongs to the Section Immunology and Infectious Diseases)
Show Figures

Figure 1

23 pages, 326 KiB  
Perspective
The Impact of Brexit on UK Food Standards and Food Security: Perspectives on the Repositioning of Neoliberal Food Policy
by Sophia Lingham, Aleksandra Kowalska, Jarosław Kowalski, Damian Maye and Louise Manning
Foods 2025, 14(9), 1474; https://doi.org/10.3390/foods14091474 - 23 Apr 2025
Cited by 1 | Viewed by 2073
Abstract
Brexit, the exiting of the United Kingdom (UK) from the European Union (EU), has impacted socio-political relationships, both internally, and externally with other countries and economic groups. This has been especially true regarding international trade, and legal and market standards for food and [...] Read more.
Brexit, the exiting of the United Kingdom (UK) from the European Union (EU), has impacted socio-political relationships, both internally, and externally with other countries and economic groups. This has been especially true regarding international trade, and legal and market standards for food and food security. This paper examines how the enacting of Brexit has framed and underlined contemporary perceptions of the UK neoliberal food system, the relative importance of food standards, and the impact of policy transition on food security. Using a positional approach, perspectives and narratives within the literature are critiqued and synthesized, including academic sources, parliamentary debates, economic reports, and media analysis. The politico-economic effects of Brexit have altered food-related relationships, recalibrating trade interactions and changing the public funding that UK farmers receive. Through realigning extractive economic models, the pre-Brexit UK food system has been reset, and new perspectives about neoliberalism have emerged. Government intervention has steered away from traditional neoliberal framings towards neo-developmentalism. A dichotomy thus exists between recognizing the intrinsic right to adequate and nutritious food and maintaining existing cultural dynamics of food supply, and the use of agri-food policy as a politico-economic tool to drive higher economic growth. The implications of this policy change are stark for UK agri-food actors within food system transition post-Brexit. Full article
(This article belongs to the Special Issue Sustainable Agriculture for Food and Nutrition Security)
26 pages, 3563 KiB  
Article
Research on Synergistic Mechanism of Upstream Subjects of Agro-Ecological Product Supply Chain—Based on the Perspective of Three Systems Evolutionary Game
by Qin Shu, Reziyan Wakasi and Yang Su
Sustainability 2025, 17(8), 3558; https://doi.org/10.3390/su17083558 - 15 Apr 2025
Viewed by 363
Abstract
The synergistic dilemma of upstream actors in the agro-ecological product supply chain restricts the transformation of ecological value, and traditional research focuses on the “production-supply” dichotomy, neglecting the driving role of the innovation service system. This study innovatively proposes a theoretical framework of [...] Read more.
The synergistic dilemma of upstream actors in the agro-ecological product supply chain restricts the transformation of ecological value, and traditional research focuses on the “production-supply” dichotomy, neglecting the driving role of the innovation service system. This study innovatively proposes a theoretical framework of “industry-supply-innovation tri-system synergy”, constructs a dynamic evolutionary game model with “free-riding” behavior, quantifies the effects of synergistic cost sharing coefficients (θ), benefit distribution ratios (γ), and policy regulation variables on the evolution of the main body’s strategy, and reveals the key laws through Matlab simulation. The results show that: (1) the participation of an innovation service system can significantly improve the speed of cooperation convergence; (2) the initial willingness to cooperate and the fairness of benefit distribution dominate the evolution path, and the probability of the system converging to “active cooperation” increases significantly when θ > 0.5; (3) the policy needs to be complemented with the market, and the government optimizes the distribution of the benefits of innovation services to improve the efficiency of the supply chain. The government can optimize the distribution of benefits from innovation services to promote the efficiency of the supply chain. Accordingly, we propose a “market-policy” dual-wheel control strategy to promote the deep integration of multiple supply chain actors with the innovation service system as a link. Full article
Show Figures

Graphical abstract

16 pages, 3222 KiB  
Article
Anisotropic Conductivity and Mechanical Strength Enhancements in Gel Polymer Electrolyte Films by Hot Pressing
by Zhifan Fang, Hao Zhang and Shuangjun Chen
Materials 2025, 18(8), 1751; https://doi.org/10.3390/ma18081751 - 11 Apr 2025
Cited by 1 | Viewed by 464
Abstract
Gel polymer electrolyte (GPE) with a polymer matrix swollen in liquid electrolytes offers several advantages over conventional liquid electrolytes, including no leakage, lightweight properties, and high reliability. While poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based GPEs show promise for lithium-ion batteries, their practical application is hindered by [...] Read more.
Gel polymer electrolyte (GPE) with a polymer matrix swollen in liquid electrolytes offers several advantages over conventional liquid electrolytes, including no leakage, lightweight properties, and high reliability. While poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based GPEs show promise for lithium-ion batteries, their practical application is hindered by the intrinsic trade-off between ionic conductivity and mechanical robustness in conventional PVDF systems. Typical strategies relying on excessive plasticizers (e.g., ionic liquids) compromise mechanical integrity. Here, we propose a novel hot-pressing-induced recrystallization strategy to synergistically enhance both anisotropic ionic conductivity and puncture strength in PVDF-based GPE films. By blending PVDF with controlled amounts of 1-hexyl-3-methylimidazolium chloride ([HMIM]Cl), followed by solution casting and hot pressing, we achieve microstructural reorganization that dramatically improves through-thickness ion transport and mechanical performance. Crucially, hot-pressed PVDF with only 25 wt% [HMIM]Cl exhibits a 12.5-fold increase in ionic conductivity (reaching 4.7 × 10−4 S/cm) compared to its solution-cast counterparts. Remarkably, this formulation surpasses the conductivity of PVDF-HFP composites with a higher [HMIM]Cl content (35 wt%, 1.7 × 10−4 S/cm), demonstrating performance optimization of anisotropic conductivity. What is more, the mechanical strength of the piercing strength perpendicular to the GPE film after hot pressing increased by 42% compared to the solution-cast film. This work establishes a scalable processing route to break the conductivity–strength dichotomy in GPEs, offering critical insights for designing high-performance polymer electrolytes. Full article
(This article belongs to the Special Issue Polymer Electrolytes: Fundamentals, Approaches and Applications)
Show Figures

Figure 1

10 pages, 236 KiB  
Review
State Thought and Migration: Analysing the Ideological Underpinnings of Temporary Migration Programmes
by Yoan Molinero-Gerbeau
Genealogy 2025, 9(1), 28; https://doi.org/10.3390/genealogy9010028 - 18 Mar 2025
Viewed by 503
Abstract
This paper analyses temporary migration programs (TMPs) as a manifestation of the “State thought” ideology, drawing on Abdelmalek Sayad’s sociological framework. Sayad considers the State central to the migration system, shaping perceptions and practices around migration through its ideological and structural dominance. The [...] Read more.
This paper analyses temporary migration programs (TMPs) as a manifestation of the “State thought” ideology, drawing on Abdelmalek Sayad’s sociological framework. Sayad considers the State central to the migration system, shaping perceptions and practices around migration through its ideological and structural dominance. The paper first explores how the State constructs hegemonic ideologies around migration, emphasising the dichotomy between nationals and non-nationals. TMPs epitomise these ideologies by promoting utilitarian migration systems that maximise economic benefits while minimising social integration. TMPs, such as agricultural guest worker schemes, enforce strict temporality, denying migrants permanence and full participation in host societies. Migrants are treated as disposable labour, restricted by non-transferable permits, and confined to precarious living conditions. The paper highlights the tension between the economic reliance on migrant labour and the State’s exclusionary policies, revealing TMPs as tools for controlling and exploiting migrants while maintaining national homogeneity. Ultimately, TMPs embody the pinnacle of “State thought”, balancing economic utility and sovereignty by perpetuating provisionality, exclusion, and systemic exploitation. The paper concludes by acknowledging migrants’ agency as they navigate and resist the structural constraints of TMPs to pursue personal and collective goals, challenging these programmes’ colonial and utilitarian underpinnings. Full article
19 pages, 4267 KiB  
Article
Investigation on the Linkage Between Precipitation Trends and Atmospheric Circulation Factors in the Tianshan Mountains
by Chen Chen, Yanan Hu, Mengtian Fan, Lirui Jia, Wenyan Zhang and Tianyang Fan
Water 2025, 17(5), 726; https://doi.org/10.3390/w17050726 - 1 Mar 2025
Cited by 1 | Viewed by 939
Abstract
The Tianshan Mountains are located in the hinterland of the Eurasian continent, spanning east to west across China, Kazakhstan, Kyrgyzstan, and Uzbekistan. As the primary water source for Central Asia’s arid regions, the Tianshan mountain system is pivotal for regional water security and [...] Read more.
The Tianshan Mountains are located in the hinterland of the Eurasian continent, spanning east to west across China, Kazakhstan, Kyrgyzstan, and Uzbekistan. As the primary water source for Central Asia’s arid regions, the Tianshan mountain system is pivotal for regional water security and is highly sensitive to the nuances of climate change. Utilizing ERA5 precipitation datasets alongside 24 atmospheric circulation indices, this study delves into the variances in Tianshan’s precipitation patterns and their correlation with large-scale atmospheric circulation within the timeframe of 1981 to 2020. We observe a seasonally driven dichotomy, with the mountains exhibiting increasing moisture during the spring, summer, and autumn months, contrasted by drier conditions in winter. There is a pronounced spatial variability; the western and northern reaches exhibit more pronounced increases in precipitation compared to their eastern and southern counterparts. Influences on Tianshan’s precipitation patterns are multifaceted, with significant factors including the North Pacific Pattern (NP), Trans-Niño Index (TNI), Tropical Northern Atlantic Index (TNA*), Extreme Eastern Tropical Pacific SST (Niño 1+2*), North Tropical Atlantic SST Index (NTA), Central Tropical Pacific SST (Niño 4*), Tripole Index for the Interdecadal Pacific Oscillation [TPI(IPO)], and the Western Hemisphere Warm Pool (WHWP*). Notably, NP and TNI emerge as the predominant factors driving the upsurge in precipitation. The study further reveals a lagged response of precipitation to atmospheric circulatory patterns, underpinning complex correlations and resonance cycles of varying magnitudes. Our findings offer valuable insights for forecasting precipitation trends in mountainous terrains amidst the ongoing shifts in global climate conditions. Full article
Show Figures

Figure 1

32 pages, 9871 KiB  
Article
Energy Trading Strategy for Virtual Power Plants with Incomplete Resource Aggregation Based on Hybrid Game Theory
by Jing Wan, Jinrui Tang, Rui Chen, Leiming Suo, Honghui Yang, Yubo Song and Haibo Zhang
Appl. Sci. 2025, 15(4), 2100; https://doi.org/10.3390/app15042100 - 17 Feb 2025
Cited by 1 | Viewed by 773
Abstract
Shared energy storage (SES) and some photovoltaic prosumers (PVPs) are difficult to aggregate by the virtual power plant (VPP) in the short term. In order to realize the optimal operation of the VPP in the incomplete resource aggregation environment and to promote the [...] Read more.
Shared energy storage (SES) and some photovoltaic prosumers (PVPs) are difficult to aggregate by the virtual power plant (VPP) in the short term. In order to realize the optimal operation of the VPP in the incomplete resource aggregation environment and to promote the mutual benefit of multiple market entities, the energy trading strategy based on the hybrid game of SES–VPP–PVP is proposed. Firstly, the whole system configuration with incomplete resource aggregation is proposed, as well as the preconfigured market rules and the general problem for the optimal energy trading strategy of VPP. Secondly, the novel hybrid game theory-based optimization for the energy trading strategy of VPP is proposed based on the multi-level game theory model. And, the corresponding solving process using Karush–Kuhn–Tucker (KKT), dichotomy, and alternating direction method of multipliers (ADMM) algorithms are also constructed to solve nonconvex nonlinear models. The effectiveness of the proposed strategy is verified through the comparison of a large number of simulation results. The results show that our proposed energy trading strategy can be used for optimal low-carbon operation of VPPs with large-scale renewable energy and some unaggregated electricity consumers and distributed photovoltaic stations, while SES participates as an independent market entity. Full article
(This article belongs to the Special Issue Design, Optimization and Control Strategy of Smart Grids)
Show Figures

Figure 1

27 pages, 2662 KiB  
Article
Export–Import Activity and Its Assessment: The Ukrainian Case
by Lyudmyla Malyarets, Svitlana Labunska, Mykola Sidak, Hanna Bilokonenko and Viktoriya Onegina
Adm. Sci. 2025, 15(2), 42; https://doi.org/10.3390/admsci15020042 - 3 Feb 2025
Viewed by 1791
Abstract
The development of export–import activity at all levels of the national economic system is an important factor and the result of globalization and country integration in the world economy. The elaboration of sound public policy related to export–import activity is based on its [...] Read more.
The development of export–import activity at all levels of the national economic system is an important factor and the result of globalization and country integration in the world economy. The elaboration of sound public policy related to export–import activity is based on its assessment and analysis. The goal of this article is the systematization and development of methodological support for the evaluation of the export–import activity of the national economy, including the development of its technology and a conceptual assessment model, which is presented in a structural–logical–semantic form, and the analysis and forecasting of export–import activity using the proposed model. To achieve the research goal, quantitative methods were used: the method of integral taxonomic indicators of development and efficiency, the method of forecasting based on trend models, multivariate factor analysis, and the modified method of cointegration of time series. A set of indicators for the export–import activity “development–effectiveness” matrix was proposed, and their dichotomies were studied. To ensure the reliability and objectivity of the export–import activity assessment, a methodological basis, which is detailed by structural elements, was formed. The model was constructed and tested based on monthly data on the export–import activity of Ukraine for the years 2021–2023. Full article
(This article belongs to the Section Strategic Management)
Show Figures

Figure 1

13 pages, 303 KiB  
Article
Dichotomy Law for a Modified Shrinking Target Problem in Beta Dynamical System
by Wenya Wang and Zhongkai Guo
Mathematics 2024, 12(23), 3680; https://doi.org/10.3390/math12233680 - 24 Nov 2024
Cited by 1 | Viewed by 721
Abstract
Let φ:N(0,1] be a positive function. We consider the size of the set [...] Read more.
Let φ:N(0,1] be a positive function. We consider the size of the set Ef(φ):={β>1:|Tβn(x)f(β)|<φ(n)i.o.n}, where “i.o.n” stands for “infinitely often”, and f:(1,)[0,1] is a Lipschitz function. For any x(0,1], it is proved that the Hausdorff measure of Ef(φ) fulfill a dichotomy law according to lim supnlogφ(n)n= or not, where Tβ is the β-transformation. In ergodic theory, the phenomenon of shrinking targets is crucial for understanding the long-term behavior of systems. By studying the shrinking target problem of the β dynamical system, we can reveal the relationship between randomness and determinism, which is significant for constructing more complex mathematical models. Moreover, there is a close connection between the β transformation and number theory. Investigating the contraction target problem helps uncover new properties and patterns in number theory, advancing the development of this field. In this work, we establish a significant relationship between the decay rate of the positive function φ(n) and the structural properties of the set Ef(φ). Specifically, we show that: The Hausdorff dimension of Ef(φ) either vanishes or is positive based on the behavior of φ(n) as n approaches infinity. The establishment of this dichotomy can help us more effectively understand the geometric characteristics and dynamical behavior of the system, thereby aiding our acceptance and comprehension of complex theories. Researching this shrinking target problem can help us uncover new properties in number theory, leading to a better understanding of the structure of numbers and promoting the development of related fields in number theory. Full article
32 pages, 453 KiB  
Article
Almost Periodic Solutions of Differential Equations with Generalized Piecewise Constant Delay
by Kuo-Shou Chiu
Mathematics 2024, 12(22), 3528; https://doi.org/10.3390/math12223528 - 12 Nov 2024
Cited by 1 | Viewed by 1145
Abstract
In this paper, we investigate differential equations with generalized piecewise constant delay, DEGPCD in short, and establish the existence and stability of a unique almost periodic solution that is exponentially stable. Our results are derived by utilizing the properties of the [...] Read more.
In this paper, we investigate differential equations with generalized piecewise constant delay, DEGPCD in short, and establish the existence and stability of a unique almost periodic solution that is exponentially stable. Our results are derived by utilizing the properties of the (μ1,μ2)-exponential dichotomy, Cauchy and Green matrices, a Gronwall-type inequality for DEGPCD, and the Banach fixed point theorem. We apply these findings to derive new criteria for the existence, uniqueness, and convergence dynamics of almost periodic solutions in both the linear inhomogeneous and quasilinear DEGPCD systems through the (μ1,μ2)-exponential dichotomy for difference equations. These results are novel and serve to recover, extend, and improve upon recent research. Full article
(This article belongs to the Special Issue The Delay Differential Equations and Their Applications)
Show Figures

Figure 1

Back to TopTop