•Pilot Free Trade Zones (PFTZ) can promote green technology innovation efficiency.•Providing reference for developing countries to develop green economy.•Proposing a more holistic index system of ...green technology innovation efficiency.•The impact of PFTZ exhibits significant spatial heterogeneity.•Market potential affects the green effect of PFTZ.
The Pilot Free Trade Zone (PFTZ) policy represents a significant step in China’s institutional innovation and broader opening-up, crucial for fostering green and high-quality economic growth. The existing literature has conducted in-depth studies on the economic effects, energy conservation, emission reduction and green innovation of PFTZs, but the effect on green technology innovation efficiency (GTIE) remains underexplored. Institutional innovation in the PFTZs will profoundly affect regional green development, and green innovation, and will certainly affect the regional GTIE. Based on this, this paper uses the city-level data of prefecture-level cities in China from 2005 to 2020 to empirically test the impact of PFTZ establishment on GTIE. First, the Super-SBM model was applied to evaluate the GTIE across 281 Chinese cities. Then, taking the establishment of PFTZs as a quasi-natural experiment, the multi-stage differentially differential model is constructed to empirically assess PFTZ policy’s impact on GTIE. The findings indicate that PFTZs can significantly enhance the GTIE. This improvement is facilitated through four pathways: the digital economy, the high-tech industries agglomeration, innovation agglomeration, and talent agglomeration. The results offer strategies for balancing external openness with environmental protection in developing countries and furnish empirical support for creating high-quality development frameworks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A new approach for solving three-dimensional elasto-plastic wheel-rail normal contact problems is presented, which is used to obtain the normal contact pressure distribution in the wheel-rail contact ...patch and its interior. First, the potential contact region dispersed by rectangular blocks is given. Then, the normal contact pressure in each block is iterated using the conjugate gradient algorithm, and the contact patch and normal contact pressure distribution under elastic conditions are obtained. After that, based on the proposed normal contact pressure correction equation and grid size correction equation, the size and normal contact pressure of each block are corrected, and so the normal contact pressure considering plastic deformation is obtained. Finally, the wheel-rail normal contact pressure under different lateral displacements and normal forces is calculated using the finite element method, and the accuracy of the proposed method is verified. Results show that the computational efficiency of the proposed approach is much higher than that of the conventional finite element method, which can provide new inspiration for railway dynamics computation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this note, we study the stability properties of linear neutral delay systems. We consider systems described by both neutral differential-difference and state-space equations, and we seek to ...determine the delay margin of such systems, that is, the largest range of delay values for which a neutral delay system may preserve its stability. In both cases, we show that the delay margin can be found by computing the eigenvalues and generalized eigenvalues of certain constant matrices, which can be executed efficiently and with high precision. The results extend previously known work on retarded systems, and demonstrate that similar stability tests exist for neutral systems; in particular, the tests require essentially the same amount of computation required for retarded systems.
In this paper, we study the robust stability of uncertain time-delay systems. We consider uncertain quasi-polynomials whose coefficients may vary in a certain prescribed range. Our goal is to derive ...necessary and sufficient conditions for such uncertain quasi-polynomials to maintain stability independent of delay parameters. Our primary contributions are frequency-sweeping conditions for interval, diamond, and spherical quasi-polynomial families, which can be readily checked, requiring only the computation of two simple frequency-dependent functions. Additionally, we also obtain vertex- and edge-type results in the spirit of the Kharitonov approach known in robust stability analysis, showing that the stability of interval and diamond quasi-polynomials can be ascertained by checking the stability of certain special vertex and/or edge members in those families. Both type of results provide necessary and sufficient conditions for the quasi-polynomial families to be robustly stable independent of delay.
In this technical note we present a stability analysis approach for polynomially-dependent one-parameter systems. The approach, which appears to be conceptually appealing and computationally ...efficient and is referred to as an eigenvalue perturbation approach, seeks to characterize the analytical and asymptotic properties of eigenvalues of matrix-valued functions or operators. The essential problem dwells on the asymptotic behavior of the critical eigenvalues on the imaginary axis, that is, on how the imaginary eigenvalues may vary with respect to the varying parameter. This behavior determines whether the imaginary eigenvalues cross from one half plane into another, and hence plays a critical role in determining the stability of such systems. Our results reveal that the eigenvalue asymptotic behavior can be characterized by solving a simple generalized eigenvalue problem, leading to numerically efficient stability conditions.
The dual control for a class of discrete-time linear-quadratic Gaussian problems with unknown parameters is studied in this paper. To achieve an optimality in dual control, a control law must possess ...a property of active learning. The best possible (partial) closed-loop feedback control law is derived in this paper by exploring the future nominal posterior probabilities, thus taking into account the effect of future learning when constructing an optimal nominal control law.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This two-part paper is concerned with stability analysis of linear systems subject to parameter variations, of which linear time-invariant delay systems are of particular interest. We seek to ...characterize the asymptotic behavior of the characteristic zeros of such systems. This behavior determines, for example, whether the imaginary zeros cross from one half plane into another, and hence plays a critical role in determining the stability of a system. In Part I of the paper we develop necessary mathematical tools for this study, which focuses on the eigenvalue series of holomorphic matrix operators. While of independent interest, the eigenvalue perturbation analysis has a particular bearing on stability analysis and, indeed, has the promise to provide efficient computational solutions to a class of problems relevant to control systems analysis and design, of which time-delay systems are a notable example. PUBLICATION ABSTRACT
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CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This paper presents an application of the eigenvalue series developed in Part I J. Chen et al., SIAM J. Control Optim., 48 (2010), pp. 5564-5582 to the study of linear time-invariant delay systems, ...focusing on the asymptotic behavior of critical characteristic zeros on the imaginary axis. We consider systems given in state-space form and as quasi-polynomials, and we develop an eigenvalue perturbation analysis approach which appears to be both conceptually appealing and computationally efficient. Our results reveal that the zero asymptotic behavior of time-delay systems can in general be characterized by solving a simple eigenvalue problem, and, additionally, when described by a quasi-polynomial, by computing the derivatives of the quasipolynomial. PUBLICATION ABSTRACT
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CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
This paper studies the stability of 2-D dynamic systems. We consider systems characterized by 2-D polynomials and 2-D state–space descriptions. For each description, we derive necessary and ...sufficient stability conditions, which all require only the computation of a constant matrix pencil. The stability of the underlying system can then be determined by inspecting the generalized eigenvalues of the matrix pencil. The results consequently yield 2-D stability tests that can be checked both efficiently and with high precision. Additionally, frequency-sweeping tests are also obtained which complement the matrix-pencil tests and are likely to be more advantageous analytically.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•A fully coupled thermo-elastic contact model of coated systems is developed.•The complex thermo-mechanical interaction is considered.•Elastic properties and thermal expansion coefficient can vary ...with temperature.•Material properties can vary arbitrarily along the depth direction of the coating.
This paper aims to develop a novel model to solve the coupled thermo-elastic sliding contact problems of coated systems. The elastic properties and thermal expansion coefficient are allowed to vary arbitrarily with temperature. The complex thermo-mechanical interaction is also considered. Additionally, there exists no limitation on the spatial distributions of thermo-elastic properties along the direction of coating thickness. Taking the thermal strain as an eigenstrain, the spatial gradient and thermo-induced change of elastic properties are depicted through the inhomogeneous inclusion theory. The resulting disturbance fields are calculated using the equivalent inclusion method. Subsequently, the thermo-elastic contact pressure is solved via the conjugate gradient method in combination with the contribution of friction-induced temperature rise to surface deformation. Based on the developed model, some parametric studies are conducted to discuss the effects of sliding velocity, friction coefficient, and material inhomogeneity on contact responses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
