Search Results (1,275)

Urban ecological resilience is essential for mitigating environmental risks, supporting green urban transitions, and promoting sustainable development. However, existing studies have mainly explained urban ecological resilience through linear and single-factor approaches, paying insufficient attention to the configurational mechanisms through which technological, financial, institutional, and structural conditions jointly shape resilience outcomes. Drawing on resilience theory, socio-ecological system theory, and synergetics, this study constructs a “risk identification–resource mobilization–institutional adaptation–structural carrying capacity” analytical framework. Using 249 prefecture-level cities in China as cases, we apply fuzzy-set qualitative comparative analysis (fsQCA) to examine how six antecedent conditions—FinTech, green finance, environmental regulation intensity, economic development, industrial structure, and urbanization—combine to generate high and non-high urban ecological resilience. The antecedent conditions are measured in 2021, while urban ecological resilience is measured in 2023 to capture the lagged effects of resilience-building conditions. The results show that no single condition constitutes a necessary condition for high urban ecological resilience, indicating that resilience is shaped by multi-condition conjunctions rather than isolated determinants. The sufficiency analysis identifies two pathways leading to high urban ecological resilience. Both pathways share FinTech, economic development, and urbanization as common foundational conditions, while green finance and industrial structure play complementary roles under different urban contexts. Specifically, the first pathway reflects a “risk identification–resource mobilization–structural carrying capacity” mechanism, whereas the second pathway reflects a “risk identification–structural carrying capacity” mechanism. In contrast, five configurations lead to non-high urban ecological resilience, demonstrating clear causal asymmetry. Non-high resilience is mainly associated with the joint absence of technological feedback, resource mobilization, and spatial carrying capacity, rather than being a simple reversal of the high-resilience pathways. These findings suggest that urban ecological resilience should be promoted through differentiated, combination-based strategies tailored to cities’ technological, financial, institutional, and structural endowments. Full article

In this paper, we investigate the problem of designing surface pencil pairs through Bertrand curves as iso-curvature lines in three-dimensional Euclidean space. By using the modified orthogonal frame and suitable marching-scale functions, we construct a pair of parametric surface pencils along a prescribed Bertrand pair. Necessary and sufficient conditions are derived for the Bertrand curves to be iso-curvature lines (isoparametric curves and curvature lines) on their corresponding surface pencils. The special case in which the curves also satisfy the isogeodesic condition is also discussed. In addition, several cases related to the torsion functions of the prescribed curves are analyzed. The construction is also extended to ruled surface pencil pairs, where the ruling directions are expressed with respect to the modified orthogonal frame. Finally, examples involving helical and planar Bertrand pairs are provided to show the effect of the controlling functions on the generated surface pencils. Full article

In the present research, necessary and sufficient conditions for the univalence of the fractional integral of the Gaussian hypergeometric function are obtained by employing specific approaches from differential subordination theory. The first theorem provides the best dominant for a particular differential subordination, which is proved to be a Carathéodory function. These results facilitate the establishment of several corollaries that give the necessary and sufficient conditions for this fractional operator to be a function with a positive real part of the first derivative. The univalence properties obtained through this research enhance the potential for new applications in geometric function theory and related research domains. Full article

A generalized $(a,b)$-knight’smove is an outcome when the knight moves on a rectangular chessboard a cells in either the horizontal or vertical direction, followed by a perpendicular move of b cells. An $(a,b)$-knight’s tour on a chessboard is a sequence of $(a,b)$-knight’s moves such that the knight visits every cell of the chessboard exactly once. Such a tour is said to be closed if the final position of the knight coincides with its initial position; otherwise, the tour is said to be open. In this paper, we investigate the existence of open $(2,3)$-knight’s tours on an $m\times n$ rectangular chessboard. In particular, we establish sufficient and necessary conditions under which a $5p\times n$ rectangular chessboard admits an open $(2,3)$-knight’s tour. The results presented here provide a complete characterization for this class of rectangular chessboards. Full article

Green innovation performance (GIP) in new energy enterprises emerges from complex interactions among technological, organizational, and institutional resource subsystems, yet existing research predominantly applies linear, single-factor approaches that fail to capture this systemic complexity. Drawing on the Resource-Based View (RBV) and systems thinking, this study employs fuzzy-set qualitative comparative analysis (fsQCA) on a sample of 54 Chinese A-share listed new energy enterprises—spanning wind power, solar power, hydrogen energy, energy storage, and new energy equipment manufacturing—observed over the 2019–2023 period, to examine the configurational pathways through which these firms achieve high GIP. Green patent grants serve as the outcome measure, and six conditions spanning three resource subsystems are considered: digital transformation and R&D intensity (technological subsystem), firm size and ownership structure (organizational subsystem), and government subsidies and carbon emission performance (institutional subsystem). Three key findings emerge. First, none of the six conditions is individually necessary for high GIP (all consistency scores below 0.90), indicating that high GIP reflects combinations of resources rather than a single driver. Second, the six sufficient configurations identified collapse into two distinct pathway clusters: a “SOE digital-empowerment-driven” cluster, in which digital transformation combines with R&D investment, government subsidies, or organizational scale within state-owned enterprises, and a “resource–capability synergy and substitution” cluster, in which scale resources, R&D investment, and policy support combine with or substitute for digital transformation regardless of ownership. Third, digital transformation appears in five of the six pathways, indicating that it functions as a key—but not universal—enabling element whose effectiveness depends on its alignment with other system components. Beyond confirming that multiple, equally valid resource combinations lead to high GIP, this study’s principal contribution is to embed RBV within an explicit systems framework, showing how technological, organizational, and institutional resources interact as subsystems of a single socio-technical system, and to translate the resulting configurations into differentiated, pathway-specific guidance for enterprises and policymakers navigating the low-carbon energy transition. Full article

Titanium dioxide is used as a white pigment in cosmetics and other products, but it possesses photocatalytic activity and has become problematic for decomposing sebum when exposed to sunlight. Consequently, titanium phosphate has been investigated as a new white pigment, with expectations for its biocompatibility. However, this pigment had the drawback of having particles that were too large. Therefore, in this study, as a new process for cosmetic pigments, we prepared samples where titanium hydroxide and titanium phosphate were coprecipitated, and we attempted to create a mixed material of titanium oxide and titanium phosphate by heating. This method aimed to suppress photocatalytic activity and produce a novel pigment with particle sizes suitable for cosmetics. With this method, thorough rinsing with water is necessary to remove the sodium sulfate. Even in samples with a low phosphorus ratio of Ti/P = 10/1, photocatalytic activity was sufficiently suppressed. Under this Ti/P = 10/1 condition, the drawback of excessively large particle sizes typically found in phosphate pigments is not particularly noticeable. This study is expected to contribute to the development of new white pigments for use in cosmetics. Full article

Accurate mine pressure prediction is essential for understanding roof–support interaction and supporting intelligent monitoring in fully mechanized longwall mining. In underground production, hydraulic-support pressure sensors provide continuous pressure sequences that reflect the mechanical response of the support–roof system. However, these sequences are affected by local mining disturbances, missing records, abnormal zero-value segments, nonstationary fluctuations, and periodic weighting, which make future pressure forecasting challenging. To address this issue, an LSTM–Transformer hybrid model is proposed for hydraulic-support pressure forecasting. The LSTM module extracts local nonlinear pressure-evolution features from recent historical windows, whereas the Transformer module captures temporal dependencies and periodic pressure patterns through global sequence modeling. Support-wise experiments were conducted using field monitoring data from Yili No. 1 Mine, and the pressure sequence of each support was processed independently to avoid mixing information from different support locations. In the representative test case, the proposed model achieved an R² of 0.971 and reduced the MAE to 0.471 MPa, while improving the phase consistency of predicted pressure peaks. Further analysis indicates that sufficient historical data coverage is necessary to capture complete pressure-evolution cycles, and that the 25-step forecasting case maintains stable accuracy for short-term mine pressure estimation. These findings demonstrate the feasibility of the proposed approach for hydraulic-support pressure prediction under the monitored conditions of the studied working face. Full article

Digital technologies are increasingly embedded in tourism performing arts, yet technology-intensive projects do not automatically generate profound cultural experiences. To explain this high-investment-but-low-experience dilemma, this study conceptualizes digital technology-enabled cultural experience as a configurational outcome of technological conditions and visitor-side psychological processing. Drawing primarily on the S-O-R framework and interpreted from a socio-technical systems perspective, digital technology interactivity and innovativeness are treated as stimulus conditions, while cognitive evaluation, scenario construction, and flow experience are treated as organism-level processing conditions. Psychological ownership theory is employed as a supplementary interpretive lens—rather than as a directly measured or tested mechanism—to explain why divergent configurational pathways may converge on high cultural experience through control, intimate understanding, and self-investment. Using fuzzy-set qualitative comparative analysis (fsQCA) with 540 valid questionnaires from visitors to tourism performing arts, the study finds that no single condition is necessary for high cultural experience. Instead, five sufficient configurations are identified: interaction–cognitive compensation, interaction–cognitive–flow synergy, dual-technology traction, innovation–scenario–immersion drive, and innovation–cognitive–flow compensation. The pathway to non-high cultural experience is asymmetric and is mainly characterized by the concurrent absence of technological, cognitive, scenario, and flow conditions. The findings re-specify the application of S-O-R theory in a configurational analytical context and provide a cautious socio-technical explanation of how technological and psychological conditions jointly shape cultural experience. Full article

Digital transformation has become a central public-sector reform agenda, yet high digital governance performance remains uneven across subnational governments. Although digital governance is expected to strengthen administrative capacity and service delivery, less is known about the policy pathways through which such performance is achieved. Drawing on the Technology–Organization–Environment framework, this study examines six implementation conditions: technological management capability, digital infrastructure development level, organizational strategy, attention to digital governance, public demand, and intergovernmental competitive pressure. Applying fuzzy-set qualitative comparative analysis to 31 provincial-level cases in China, the study finds that organizational strategy is necessary but insufficient, and that no single condition alone explains high performance. Four sufficient policy pathways are identified and summarized into three implementation mechanisms: technology–organization synergy, competition-pressure reinforcement, and demand compensation. The findings show that high public-sector digital governance performance is shaped by aligned implementation conditions rather than isolated technological investment. Full article

This article explores properties of conformal vector fields on a Riemannian manifold, focusing on conditions that lead to the manifold being isometric to the Euclidean space. Given a conformal vector $\zeta$ with conformal factor $\sigma$ on a Riemannian manifold $\left(N,g\right)$, there is naturally associated a skew-symmetric tensor $\chi$ to $\zeta$ called the essential tensor of $\zeta$. It is shown that the essential tensor $\chi$ plays a vital role in our study. We intend to analyze when a conformal vector field becomes a Killing vector field. In a first result of this article, we obtain a necessary and sufficient geometric condition on a complete and connected Riemannian manifold $\left(N,g\right)$ admitting a conformal vector field $\zeta$ so that $\zeta$ is a Killing vector field. In the rest of the article, we obtain characterizations of a Euclidean space using conformal vector fields. In the first such result, it is shown that an n-dimensional complete and connected Riemannian manifold $\left(N,g\right)$, $n>2$ admits a conformal vector field $\zeta$ with conformal factor $\sigma \ne 0$ and essential tensor $\chi$ such that the affinity tensor of $\nabla \sigma$ is zero, the function $\zeta \left(\sigma \right)$ is a constant, and $\zeta$ annihilates $\chi$ if and only if $\left(N,g\right)$ is isometric to the Euclidean space $E^n$. Similarly, in a second characterization of the Euclidean space $E^n$ using a conformal vector field $\zeta$, we use the following conditions: $\zeta$ annihilates the Ricci operator S, $\nabla \sigma$ annihilates $\chi$, and the vector field $\chi \left(\zeta \right)$ is incompressible. Finally, we consider a conformal vector field $\zeta$ with conformal factor $\sigma \ne 0$ and essential tensor $\chi$ on a complete and connected Riemannian manifold $\left(N,g\right)$ such that the Hessian operator $H_{\sigma }$ is invariant under the local flow of $\zeta$ so that the function $\zeta \left(\sigma \right)-{\sigma }^2$ is a subharmonic function and $\zeta$ annihilates $\chi$, and show that $\left(N,g\right)$ is isometric to the Euclidean space $E^n$. The converse holds as well. Full article

This paper investigates the stabilization of unstable third-order Multiple-Input Multiple-Output (MIMO) systems whose interaction structure is described by a doubly stochastic combined matrix, also known as the Relative Gain Array (RGA). Starting from systems with negative Niederlinski index, we derive necessary and sufficient conditions under which stability can be recovered through diagonal perturbations while preserving the doubly stochastic structure of the combined matrix. By exploiting the canonical representation of matrices associated with a prescribed combined matrix and the invariance properties under diagonal equivalence, the problem is reduced to a structured parametric form that allows a complete algebraic characterization. Special attention is given to perturbations involving the (1, 1) entry and one additional diagonal entry, leading to explicit bounds on the perturbation parameters that guarantee stabilization. The results extend previous papers on diagonal perturbations of combined matrices and provide a constructive method for stabilizing MIMO systems without altering their interaction pattern. Numerical examples illustrate the applicability of the proposed approach. Full article

This paper develops a unified Lorentzian framework for persistent rigid motions generated by slant helices in three-dimensional Minkowski space and investigates their geometric and kinematic properties. Persistence is characterized by the constancy of the pitch of the instantaneous twist associated with a one-parameter rigid motion in the Poincaré group $\mathrm{ISO}(2,1)$. Interpreting curves in the motion group as trajectories of rigid motions, we study Frenet–Serret and adapted frame motions determined by slant helices under different causal characters. Necessary and sufficient conditions are established for these frame motions to generate persistent Lorentzian motions. An explicit intrinsic relationship between the pitches of Frenet–Serret and adapted frame motions is obtained in terms of the geodesic curvature of the spherical image of the principal normal indicatrix, showing that persistence is governed by intrinsic curve invariants and is independent of the chosen moving frame. The geometric structure of persistent motions is further clarified through associated ruled surfaces. In particular, the pitch of a persistent motion is shown to coincide with the distribution parameter of the ruled surface associated with the corresponding frame motion. Illustrative examples are presented for different causal configurations. These results extend classical Euclidean theory of persistent rigid motions to the Lorentzian setting and provide a unified framework connecting curve theory, frame geometry, ruled surfaces, and Lorentzian kinematics. Full article

In the present work, we study a class of nonhomogeneous linear systems with fractional derivatives in Caputo’s sense of incommensurate order and distributed delays, satisfying the Perron condition. More precisely we study the impact of the Perron condition on the boundedness of the fundamental and extended fundamental matrices of the corresponding homogeneous system. We prove that if the nonhomogeneous system satisfies the Perron condition, then the fundamental matrix $C(t,s)$ and the extended fundamental matrix $Q(t,s)$ of the homogeneous system are uniformly bounded. As a consequence we obtain that the boundedness of the matrix $Q(t,s)$ is a necessary and sufficient condition for the uniform stability of the zero solution of the homogeneous system. Furthermore, we also prove that the extended fundamental matrix $Q(t,s)$ tends to zero when $t\to \infty$, which is a necessary and sufficient condition for the uniform asymptotic stability of the zero solution of the homogeneous system under study. Full article

Glaucoma is a chronic, progressive optic neuropathy and the second leading cause of irreversible blindness worldwide. Although elevated intraocular pressure (IOP) remains the principal modifiable risk factor, it is neither necessary nor sufficient for disease development. The literature indicates that systemic conditions such as obstructive sleep apnea (OSA) may contribute to its pathogenesis. The pathophysiology of glaucoma is supported by several theories, primarily the mechanical and vascular theories. This review describes the pathophysiological links between OSA and glaucoma considering current theories. The principal connecting mechanism appears to be chronic intermittent hypoxia and reduced ocular perfusion pressure, which trigger optic nerve head hypoxia, oxidative stress, and biomechanical remodeling of the lamina cribrosa. These processes interact within a vicious cycle that progressively compromises the metabolic support of optic nerve axons. The mechanisms described are particularly relevant to normal-tension glaucoma, which may be associated with OSA. Retinal nerve fiber layer thinning appears among the earliest markers of optic nerve vulnerability, whereas IOP and visual field changes are more variable. These observations underscore the clinical relevance of the OSA–glaucoma relationship and support a multidisciplinary approach incorporating routine ophthalmic screening for subclinical optic nerve damage. Full article

The security of new energy vehicle (NEV) industry chains has become a strategic issue for industrial competitiveness, the energy transition, and economic security. This study examines how digital economy capabilities jointly support NEV industry chain security across 30 provincial-level administrative regions in China. Drawing on Organizational Information Processing Theory and Dynamic Capability Theory, we conceptualize artificial intelligence capability (AIC), big data analytics capability (BDA), cloud computing infrastructure (CCI), and blockchain application level (BCL) as complementary information-processing and reconfiguration capabilities. We combine Necessary Condition Analysis (NCA), fuzzy-set Qualitative Comparative Analysis (fsQCA), and Random Forest/SHAP analysis. The revised results show that AIC is a practically necessary condition for supply chain resilience, BDA is a necessary condition for achieving a high cybersecurity level, and BCL is a dimension-specific necessary condition for data security. Four sufficient configurational paths—technology-driven, data-driven, infrastructure-driven, and security-synergistic—lead to high comprehensive NEV industry chain security. Robustness checks using alternative calibration anchors and consistency thresholds show that the core configurations are stable. A revised machine learning specification using only digital economy predictors confirms the high relative importance of AIC. It also shows that the marginal contribution of AIC tends to flatten beyond the upper-middle range. The findings provide a configurational and regionally differentiated perspective on digital economy empowerment while avoiding overgeneralization beyond the Chinese provincial context. Full article