Search

The star sensor is the most accurate measurement instrument in the spacecraft attitude measurement system, and the accurate centroid of the star point is the basis for ensuring the performance of the star sensor. Currently, the centroid of the gray method is the most widely used centroid extraction method in practice. Systematic errors caused by the centroid of the gray method and random noise in the detector imaging process are the main factors contributing to the deviation of the star centroiding coordinates. Considering the relationship between the point spread function and the pixel gray value, this paper proposes a centroiding method to reduce the star point centroiding error by fusing a priori information and energy distribution. The star charts are first preprocessed using a curvature filter and Gaussian blur to reduce the random noise. Then the complexity of the point spread function is considered, and the pixel gray values are corrected based on a priori information and gray value fuzzy processing. Finally, the symmetry of the one-dimensional energy distribution is used to quickly determine the sub-pixel deviation to get the star centroid coordinates. Through simulation and physical simulation experiments, the method was verified to be effective, and the extraction accuracy met the requirements of high-precision star sensors. The night sky observation test results demonstrate that the method in this paper can improve the measurement accuracy of the star sensors. [ABSTRACT FROM AUTHOR]

This paper argues that 'dirty hands' (DH) scenarios, where an agent is forced to do wrong in order to do right, are conceptually coherent. The charge of incoherence is a widespread and common criticism made by deontologists and consequentialists alike. They argue that DH theorists erroneously assume the existence of real moral dilemmas and then compound this error by claiming that it is possible to engage in justified moral wrongdoing. However, such critics argue that there are only prima facie moral dilemmas and hence it is not only irrational and obtuse to argue for DH scenarios, but also undermines our search for sound moral judgments in very difficult situations. Given the gravity of these charges, surprisingly little has been written in defence of DH as a coherent and necessary part of our moral vocabulary. If there can be no successful defence of the possibility of DH, then all talk of such scenarios become futile. This paper responds to two influential and what initially appear to be strongly plausible arguments used by critics of DH. I call these the 'Arguments from Deontic Logic' and the 'All-Things-Considered Argument'. I present three responses which seek to raise serious doubts about their efficacy. I then support the possibility of DH by exploring what we can learn about our moral reality from the moral emotion of 'tragic remorse'. This approach endorses the role of emotions in determining moral knowledge. It also rejects the view that ethical theories ought to dismiss DH experiences as incoherent in favour of questionable theoretical a priori assumptions, which seek a reductionist account of our moral reality. [ABSTRACT FROM AUTHOR]

With the continuous development of virtual reality, digital image applications, the required complex scene video proliferates. For this reason, portrait matting has become a popular topic. In this paper, a new matting algorithm with improved portrait details for images with complex backgrounds (MORLIPO) is proposed. This work combines the background restoration module (BRM) and the fine-grained matting module (FGMatting) to achieve high-detail matting for images with complex backgrounds. We recover the background by inputting a single image or video, which serves as a priori and aids in generating a more accurate alpha matte. The main framework uses the image matting model MODNet, the MobileNetV2 lightweight network, and the background restoration module, which can both preserve the background information of the current image and provide a more accurate prediction of the alpha matte of the current frame for the video image. It also provides the background prior of the previous frame to predict the alpha matte of the current frame more accurately. The fine-grained matting module is designed to extract fine-grained details of the foreground and retain the features, while combining with the semantic module to achieve more accurate matting. Our design allows training on a single NVIDIA 3090 GPU in an end-to-end manner and experiments on publicly available data sets. Experimental validation shows that our method performs well on both visual effects and objective evaluation metrics. [ABSTRACT FROM AUTHOR]

Digitalisation and computation presents us with a vague empirical world that unsettles established links between measurements and values. As more and more actors use digital media to produce data about aspects of the world they deem important, new possibilities for inscribing their lives emerge. The practical work with digital methods thus often involves the production of social visibilities that are misfits in the context of established data practices. In this paper I argue that this dissonance carries the distinct critical potential to design data experiments that (a) uses the act of operationalisation as an engine for creating intersubjective clarity about the meaning of existing concepts and (b) takes advantage of algorithmic techniques to provoke a reassessment of some of the core assumptions that shape the way we pose empirical problems are normally framed. Drawing on the work of Kant, Peirce, Dewey and C.I. Lewis I propose to think of this critical potential as the possibility to practice what I term 'experimental a priori' and I use qualitative vignettes from two years of data experiments with GEHL architects to illustrate what this entails in practice. Faced with the task of using traces from Facebook as an empirical source to produce a map of urban political diversity, the architects found themselves in a need to revisit inherited assumptions about the ontology of urban space and the way it can even be formulated as a problem of diversity. While I describe this as a form of obstructive data practice that is afforded by digital methods, I also argue that it cannot be realised without deliberate design interventions. I therefore end the paper by outlining five design principles that can productively guide collective work with digital methods. These principles contribute to recent work within digital STS on the recalibration of problem spaces and the design of data sprints. However, the concept of 'experimental a priori' can also serve as a philosophical foundation for knowledge production within computational humanities more broadly. [ABSTRACT FROM AUTHOR]

Guaranteed lower Dirichlet eigenvalue bounds (GLB) can be computed for the m-th Laplace operator with a recently introduced extra-stabilized nonconforming Crouzeix–Raviart ( m = 1 ) or Morley ( m = 2 ) finite element eigensolver. Striking numerical evidence for the superiority of a new adaptive eigensolver motivates the convergence analysis in this paper with a proof of optimal convergence rates of the GLB towards a simple eigenvalue. The proof is based on (a generalization of) known abstract arguments entitled as the axioms of adaptivity. Beyond the known a priori convergence rates, a medius analysis is enfolded in this paper for the proof of best-approximation results. This and subordinated L 2 error estimates for locally refined triangulations appear of independent interest. The analysis of optimal convergence rates of an adaptive mesh-refining algorithm is performed in 3D and highlights a new version of discrete reliability. [ABSTRACT FROM AUTHOR]

This paper argues that no form of meaningful development can be discussed without an incursion into the realm of consciousness, from which ideas emanate. This paper demonstrates that human civilization is driven by notions such as ideas, imaginations, concepts, plans, and projects which are germane to social development. An examination of Kant’s theory of concept formation reveals that though objects are given to us by means of sensibility, it is through the understanding that concepts arise. The mind therefore becomes the ‘breeding’ ground from which our ideas are generated and organized. In Kant’s analysis of the faculty of understanding, he noted that there are a priori pure intuitions and sets of categories such as Quality, Relation, Modality that organize particular sensations into unified objects of experience. This capacity of the mind enables it to produce or generate ideas within its own operations. Ideas generated are used to recreate our world. This paper provides a conceptual framework to explicate the foundation of development. Using the method of analysis, this essay concludes that the basis of development – social, economic, and cultural – is hinged on the nature and role of the mind. [ABSTRACT FROM AUTHOR]

This paper is concerned with nonlocal fractional p-Laplacian Schrödinger–Hardy-type equations involving concave–convex nonlinearities. The first aim is to demonstrate the L ∞ -bound for any possible weak solution to our problem. As far as we know, the global a priori bound for weak solutions to nonlinear elliptic problems involving a singular nonlinear term such as Hardy potentials has not been studied extensively. To overcome this, we utilize a truncated energy technique and the De Giorgi iteration method. As its application, we demonstrate that the problem above has at least two distinct nontrivial solutions by exploiting a variant of Ekeland's variational principle and the classical mountain pass theorem as the key tools. Furthermore, we prove the existence of a sequence of infinitely many weak solutions that converges to zero in the L ∞ -norm. To derive this result, we employ the modified functional method and the dual fountain theorem. [ABSTRACT FROM AUTHOR]

In this paper, we consider a fractional Nernst-Planck-Poisson-Navier-Stokes system in ℝ³. First, we obtain a priori estimates by using energy estimates. Then, we construct an iterative solution sequence by solving the approximate problem and obtaining the local existence and uniqueness of the classical solution. Finally, combining the local existence with a priori estimates, the global existence and uniqueness of the classical solution with small initial data are obtained. [ABSTRACT FROM AUTHOR]

The higher-order guaranteed lower eigenvalue bounds of the Laplacian in the recent work by Carstensen et al. (Numer Math 149(2):273–304, 2021) require a parameter C st , 1 that is found not robust as the polynomial degree p increases. This is related to the H 1 stability bound of the L 2 projection onto polynomials of degree at most p and its growth C st, 1 ∝ (p + 1) 1 / 2 as p → ∞ . A similar estimate for the Galerkin projection holds with a p-robust constant C st , 2 and C st , 2 ≤ 2 for right-isosceles triangles. This paper utilizes the new inequality with the constant C st , 2 to design a modified hybrid high-order eigensolver that directly computes guaranteed lower eigenvalue bounds under the idealized hypothesis of exact solve of the generalized algebraic eigenvalue problem and a mild explicit condition on the maximal mesh-size in the simplicial mesh. A key advance is a p-robust parameter selection. The analysis of the new method with a different fine-tuned volume stabilization allows for a priori quasi-best approximation and improved L 2 error estimates as well as a stabilization-free reliable and efficient a posteriori error control. The associated adaptive mesh-refining algorithm performs superior in computer benchmarks with striking numerical evidence for optimal higher empirical convergence rates. [ABSTRACT FROM AUTHOR]

In this paper, a high-accuracy conservative implicit algorithm for computing the space fractional coupled Schrödinger–Boussinesq system is constructed. Meanwhile, the conservative nature, a priori boundedness, and solvability of the numerical solution are presented. Then, the proposed algorithm is proved to be second-order convergence in temporal and fourth-order spatial convergence using the discrete energy method. Finally, some numerical experiments validate the effectiveness of the conservative algorithm and confirm the accuracy of the theoretical results for different choices of the fractional-order α. [ABSTRACT FROM AUTHOR]

Convolutional neural network based methods have been proposed to address blind deblurring. Aiming at the difficulty of reconstructing high-frequency features of images with existing network models, this paper proposes a two-stage convolution-based encoder-decoder for fusing high-frequency a prior. In the first stage, both blurred and high-frequency images are input, and the image features extracted by the network and the high-frequency features are fused. In the second stage, the fused features are further refined and recovered as potentially clear images, and the reconstruction ability of the model for high-frequency features is enhanced. In addition, this paper proposes a deep feature reorganization module that integrates multi-layer semantic information in the encoder-decoder and targets the encoder semantics to further enhance the feature characterization capability of the model. Comprehensive experimental results show that our method achieves 0.9085 structural similarity index (SSIM) and 30.66db peak signal-to-noise ratio (PSNR) on the GoPro dataset. Meanwhile, our method achieves 0.8514 SSIM and 27.39db PSNR on the Lai dataset. [ABSTRACT FROM AUTHOR]

This paper investigates a novel C 0 nonconforming virtual element method (VEM) for solving the Kirchhoff plate obstacle problem, which is described by a fourth-order variational inequality (VI) of the first kind. In our study, we distinguish our approach by introducing new internal degrees of freedom to the traditional lowest-order C 0 nonconforming VEM, which originally lacked such degrees. This addition not only facilitates error estimation but also enhances its intuitiveness. Importantly, our novel C 0 nonconforming VEM naturally satisfies the constraints of the obstacle problem. We then establish an a priori error estimate for our novel C 0 nonconforming VEM, with the result indicating that the lowest order of our method achieves optimal convergence. Finally, we present a numerical example to validate the theoretical result. [ABSTRACT FROM AUTHOR]

Copyright of Studies in Hispanic & Lusophone Linguistics is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Few-shot classification is one of the most daunting challenges in deep learning. The complexities of this task arise from the fact that category targets are often embedded within intricate and diverse background pixels, resulting in inconspicuous category features. Moreover, obtaining common category characteristics from a limited number of samples is difficult. Compounding the issue, models encounters categories that they have never seen before, rendering the prior guarantee of interclass variance infeasible. To address these dilemmas, this paper leverages the apriori conditioned information of few-shot tasks and introduces a Conditioned Feature Reconstruction Network (CFRN). The CFRN employs prototype reconstruction to minimize the prototype similarity among different classes and query reconstruction to maximize the similarity of (query, prototype) feature pairs. This approach increases the interclass variance while decreasing the intraclass variance, thereby enhancing separability and improving the saliency of the target features. An experimental validation demonstrates the effectiveness of the CFRN, which obtains state-of-the-art results on the mini-ImageNet, tiered-ImageNet, and CUB datasets. [ABSTRACT FROM AUTHOR]

This research explores the pos tag sequences that shape the transition from upper intermediate (B2 cefr) to near-native proficiency (C2 cefr) in a corpus of essays (n=32,410) from the Cambridge Learner Corpus. Gilquin (2018) and others have shown that pos tag sequences offer a holistic approach to extracting the most commonly used patterns without a starting point of an a priori set of words and word sequences. Using corpus linguistics informed by usage-based theories of language learning, this paper examines the frequency and distribution of 4-slot pos-tag sequences in L2 English writing, drawing on the taxonomy of pattern grammar (Francis et al., 1996, 1998; and Hunston and Francis, 2000). Findings point to the presence of both core and emergent pos-tag sequences in learner language in the two proficiency levels analysed. These sequences point to the presence of dynamic language restructuring processes as learners become more proficient and re-evaluate their understanding of frequency and distribution in English. This paper shows evidence of how language competence increases with proficiency. The research offers new evidence in our understanding of the development of L2 writing in efl contexts. [ABSTRACT FROM AUTHOR]

The chemist Jeremias Benjamin Richter (1762–1807) coined the term "stoichiometry" and proposed the "law of definite proportions." He is also commonly acknowledged as having been a student of Immanuel Kant (1724–1804). This paper demonstrates how Kant's philosophy positively shaped Richter's approach to chemistry in the Anfangsgründe der Stöchiometrie (1792–1794) and outlines two ways in which Richter attempted to represent the chemical force in "pure intuition": (1) "reductionistic forces," in which qualitative features scale with the quantity of matter; and (2) generalized "abstracted forces," in which a plurality of dissolution- and bonding-properties are latent within the chemical in the manifold of space-time. [ABSTRACT FROM AUTHOR]

This paper is concerned with identification of a spatial source function from final time observation in a bi-parabolic equation, where the full source function is assumed to be a product of time dependent and a space dependent function. Due to the ill-posedness of the problem, recently some authors have employed different regularization method and analysed the convergence rates. But, to the best of our knowledge, the quasi-reversibility method is not explored yet, and thus we study that in this paper. As an important implication, the Hölder rates for the apriori and aposteriori error estimates obtained in this paper improve upon the rates obtained in earlier works. Also, in some cases we show that the rates obtained are of optimal order. Further, this work seems to be the first one that has broaden the applicability of the problem by allowing the time dependent component of the source function to change sign. To the best of our knowledge, the earlier known work assumed the fixed sign of the time dependent component by assuming some bounded below condition. [ABSTRACT FROM AUTHOR]

In this paper a two grid algorithm for quasilinear elliptic problem based on virtual element method (VEM) discretization is proposed. With this new algorithm the solution of a quasilinear elliptic problem on a fine grid is reduced to the solution of a quasilinear elliptic problem on a much coarser grid, and the solution of a linear system on the fine grid. A priori error estimate in H1 norm is derived. Numerical experiments are carried out to illustrate the theoretical findings. [ABSTRACT FROM AUTHOR]

We present a priori estimates and unique solvability results in the mixed-norm Lebesgue spaces for the kinetic Kolmogorov-Fokker-Planck (KFP) equation in divergence form. The leading coefficients are bounded uniformly nondegenerate with respect to the velocity variable v and satisfy a vanishing mean oscillation (VMO) type condition. We consider the L2 case separately and treat more general equations, which include the relativistic KFP equation. This paper is a continuation of our previous work on Lp estimates for KFP equations in nondivergence form. [ABSTRACT FROM AUTHOR]

Peirce and Dewey were generally more concerned with the process of scientific activity than purely mathematical work. However, their accounts of knowledge production afford some insights into the epistemology of mathematical postulates, especially definition and axioms. Their rejection of rationalist metaphysics and their emphasis on continuity in inquiry provides the pretext for the pragmatic a priori - hypothetical and operational assumptions whose justification relies on their fruitfulness in the long run. This paper focuses on the application of this idea to the epistemology of definitions and an account of progress in mathematics, although it has broader implications for the study of conceptual change and the function and basis of presuppositions in the sciences. [ABSTRACT FROM AUTHOR]

One of Kripke's innovations concerning the philosophy of language is the doctrine that the truth of some metaphysically necessary propositions is only known a posteriori. The typical example he gives is the identity statement consists of two different proper names that refer to the same referent, like "Hesperus = Phosphorus". By metaphysically necessary he means that the proposition is true in all possible worlds and by a posteriori knowledge he means that its truth is known by experiment or investigation. Some philosophers have given arguments against Kripke's doctrine and claimed that such propositions can, also, be known a priori. In this paper, I will defend Kripke's view by showing that his approach to the issue is linguistic not metaphysical, opposite to his critics. [ABSTRACT FROM AUTHOR]

Copyright of Runa: Archivo para las Ciencias del Hombre is the property of Runa: Archivo para las Ciencias del Hombre and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista de Filosofía UIS is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we provide some results pertaining to asymptotic behaviour as ε → 0 of the finite-energy sequences of the one-dimensional Cahn-Hilliard functional ... where u ∊ H1(0, 1), and where W is a multi-well potential endowed with a non-standard integrability condition. We introduce a new class of finite-energy sequences, recover its underlying geometric properties as ε → 0, and obtain the related a priori estimates. [ABSTRACT FROM AUTHOR]

A family of allocation rules for cooperative games with a priori unions is introduced in this paper. These allocation rules, which will be called rough Shapley values, are extensions of the well-known Shapley value for classical cooperative games. The family of rough Shapley values, which is constructed by using rough sets to describe different cooperative options, includes several of the extensions of the Shapley value found in the literature. We prove that the rough Shapley values are the allocation rules for games with a priori unions that satisfy some reasonable properties. [ABSTRACT FROM AUTHOR]

In this paper, we explore the version of Hairer's regularity structures based on a greedier index set than trees, as introduced in (Otto et al. in A priori bounds for quasi-linear SPDEs in the full sub-critical regime, 2021, arXiv:2103.11039) and algebraically characterized in (Linares et al. in Comm. Am. Math. Soc. 3:1–64, 2023). More precisely, we construct and stochastically estimate the renormalized model postulated in (Otto et al. in A priori bounds for quasi-linear SPDEs in the full sub-critical regime, 2021, arXiv:2103.11039), avoiding the use of Feynman diagrams but still in a fully automated, i. e. inductive way. This is carried out for a class of quasi-linear parabolic PDEs driven by noise in the full singular but renormalizable range. We assume a spectral gap inequality on the (not necessarily Gaussian) noise ensemble. The resulting control on the variance of the model naturally complements its vanishing expectation arising from the BPHZ-choice of renormalization. We capture the gain in regularity on the level of the Malliavin derivative of the model by describing it as a modelled distribution. Symmetry is an important guiding principle and built-in on the level of the renormalization Ansatz. Our approach is analytic and top-down rather than combinatorial and bottom-up. [ABSTRACT FROM AUTHOR]

In this paper, we study the mixed virtual element approximation to an elliptic optimal control problem with boundary observations. The objective functional of this type of optimal control problem contains the outward normal derivatives of the state variable on the boundary, which reduces the regularity of solutions to the optimal control problems. We construct the mixed virtual element discrete scheme and derive an a priori error estimate for the optimal control problem based on the variational discretization for the control variable. Numerical experiments are carried out on different meshes to support our theoretical findings. [ABSTRACT FROM AUTHOR]

The considerable interest in the recent literature for nonlocal equations and their applications to a wide range of scientific problems does not appear to be supported by a corresponding advancement in the efforts toward reliable numerical techniques for their solution. The aim of this paper is to provide such an algorithm and above all to prove its high order convergence. The numerical scheme is applied to a diffusion problem in a biological context, arising in population theory. Several simulations are carried out. At first the empirical order of convergence on examples with known solution is assessed. Their results are in agreement with the theoretical findings. Simulations are then extended to cases for which the solution is not known a priori. Also in this case the outcomes support the convergence analysis. [ABSTRACT FROM AUTHOR]

This paper is concerned with the inverse problem of determining the initial value of the distributed‐order time‐fractional diffusion equation from the final time observation data, which arises in some ultra‐slow diffusion phenomena in applied areas. Since the problem is ill‐posed, we propose an iterated regularization method based on the Nesterov acceleration strategy to deal with it. Convergence rates for the regularized approximation solution are given under both the a priori and a posteriori regularization parameter choice rules. It is shown that the proposed method can always yield the order optimal convergence rates as long as the iteration parameter which appears in the Nesterov acceleration strategy is chosen large enough. In numerical aspect, the main advantage of the proposed method lies in its simplicity. Specifically, due to the Nesterov acceleration strategy, only a few number of iteration steps are required to obtain the approximation solution, and at each iteration step, we only need to numerically solve the standard initial‐boundary value problem for the distributed‐order time‐fractional diffusion equation. Some numerical examples including one‐dimensional and two‐dimensional cases are presented to illustrate the validity and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

A systematic definition of an aircraft generator's "available power" (used to supply loads on its DC bus) is given, which is defined in the context of constraints on transient and steady‐state performance. Using a geometric, data‐driven approach, such a characterisation has been achieved, and a new method, called Power availablE Estimation Tool (PEET), has been developed to determine in real‐time whether a given load can be fulfilled at a given time while maintaining power quality. This is an important problem, especially for safety critical electrical systems such as more electric aircraft, for which it is imperative to know a priori whether an added load will result in voltage variations outside of allowed values. PEET is introduced and its conceptual framework is formalised. Lastly, it provides simulation results that illustrate its performance. The results show that the PEET method produces reliable a priori estimates of power availability, and that this can be achieved within time frames that make it applicable in a real‐time implementation. [ABSTRACT FROM AUTHOR]

How, if at all, can scientific progress improve our view of the modal facts? According to rationalist approaches to modal epistemology, science has no substantive role: a priori reflection reveals the structure of modal space, and a posteriori science merely locates us within that modal space, by identifying the actual properties and structures instantiated at our world. According to modal naturalist approaches, science provides evidence about the structure of the underlying modal space. In this paper I distinguish four versions of modal naturalism, with science playing an increasingly robust evidential role, and discuss their plausibility. [ABSTRACT FROM AUTHOR]

In 1967, Alvin Goldman prominently claimed that the traditional JTB analysis is adequate for non‐empirical knowledge. Since then, this claim has remained widely unchallenged. In this paper, I show that this claim is false. I provide two examples in which a true belief is a priori justified but epistemically defective such that it does not constitute knowledge. Finally, I submit a novel analysis of a priori knowledge that avoids the Gettier problem. What is particularly important and distinctive about my analysis is that I neither need to make the justification condition so strong that only infallible justification is allowed, nor do I need to explicitly introduce a truth condition. [ABSTRACT FROM AUTHOR]

This paper presents a novel model for the discrete forcing ghost-cell method to make it applicable for eigensolution analysis, utilizing the sinusoidal property of real solutions to determine the location of mirror points, the values of which are linearly represented by the surrounding grid. This scheme can serve as an a priori analysis tool for evaluating immersed boundary methods. The analytical solution for a harmonic wave with the initial condition u (x , 0) = exp (ikx) under periodic boundary conditions is obtained. Ghost cells (GCs) are interpolated from the internal grid, and the method is shown to effectively analyze dispersion–dissipation across different GC numbers and interpolation types. Finally, the conclusions are validated by simulating the Burgers equation. [ABSTRACT FROM AUTHOR]

In the present paper, we apply the geometrical mechanism of diffusion in an a priori unstable Hamiltonian system [L. Chierchia and G. Gallavotti, Ann. l'I.H.P. Phys. théor. 60, 1–144 (1994)] with 3 + 1/2 degrees of freedom. This mechanism consists of combining iterations of the inner and outer dynamics associated with a Normally Hyperbolic Invariant Manifold (NHIM) to construct diffusing pseudo-orbits and subsequently apply shadowing results to prove the existence of diffusing orbits of the system. In addition to proving the existence of diffusion for a wide range of the parameters of the system, an important part of our study focuses on the search for Highways, a particular family of orbits of the outer map (the so-called scattering maps), whose existence is sufficient to ensure a very large drift of the action variables, with a diffusion time near them that agrees with the optimal estimates in the literature. Moreover, this optimal diffusion time is calculated, with an explicit calculation of the constants involved. All these properties are proved by analytical methods and, where necessary, supplemented by numerical calculations. [ABSTRACT FROM AUTHOR]

The truth conditions of sentences with indexicals like 'I' and 'here' cannot be given directly, but only relative to a context of utterance. Something similar applies to questions: depending on the semantic framework, they are given truth conditions relative to an actual world, or support conditions instead of truth conditions. Two-dimensional semantics can capture the meaning of indexicals and shed light on notions like apriority, necessity and context-sensitivity. However, its scope is limited to statements, while indexicals also occur in questions. Moreover, notions like apriority, necessity and context-sensitivity can also apply to questions. To capture these facts, the frameworks that have been proposed to account for questions need refinement. Two-dimensionality can be incorporated in question semantics in several ways. This paper argues that the correct way is to introduce support conditions at the level of characters, and develops a two-dimensional variant of both proposition-set approaches and relational approaches to question semantics. [ABSTRACT FROM AUTHOR]

In this paper, we establish nonlinear ellipticity of the equation of contact instantons with Legendrian boundary condition on punctured Riemann surfaces by proving the a priori elliptic coercive estimates for the contact instantons with Legendrian boundary condition, and prove an asymptotic exponential C ∞ -convergence result at a puncture under the uniform C 1 bound. We prove that the asymptotic charge of contact instantons at the punctures under the Legendrian boundary condition vanishes. This eliminates the phenomenon of the appearance of spiraling cusp instanton along a Reeb core, which removes the only remaining obstacle towards the compactification and the Fredholm theory of the moduli space of contact instantons in the open string case, which plagues the closed string case. Leaving the study of C 1 -estimates and details of Gromov-Floer-Hofer style compactification of contact instantons to [27], we also derive an index formula which computes the virtual dimension of the moduli space. These results are the analytic basis for the sequels [27–29] and [36] containing applications to contact topology and contact Hamiltonian dynamics. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to consider an optimal distributed control problem for a Cahn-Hilliard type phase field system related to tumor growth, which consists of Cahn-Hilliard equation with two relaxation terms and a reaction-diffusion equation with a suitable distributed control variable representing the concentration of cytotoxic drugs in medical treatment. We prove the well-posedness of the state system and its corresponding linearized system. Based on these results, we establish the Fréchet differentiability of the control-to-state operator and deduce the first-order necessary optimality conditions in terms of a variational inequality involving the adjoint state variables. Moreover, by establishing some a priori estimates that are uniform in some relaxation parameter, we implement the asymptotical analysis of the solutions as well as the optimal control when the relaxation parameter approaches to zero. [ABSTRACT FROM AUTHOR]

Fuel cell behavior is characterized by important electric and kinetic parameters such as charge transfer coefficient, exchange current density and ohmic resistance. The quantitative estimate of these parameters by a semi-empirical approach without resorting to the sophisticated and costly methods like AC Impedance spectroscopy is presented in this paper. A fuel cell model that describes voltage-current density behavior is utilized to acquire the fuel cell parameters by using two different kinds of fitting procedures. A set of equations suitable for fitting various regions of voltage-current density variation are proposed and the criteria used to assess the quality of fit is uniformly applied to all the fitting procedures. The importance of leakage current as a parameter is also discussed by presenting improved form of fuel cell model. The model is fitted on the DC Impedance (Polarization) curve experimental data obtained for liquid feed passive Direct Methanol Fuel Cell (DMFC) at different methanol feed concentration and the operating torque. After establishing the applicability of the model and the proposed fitting procedure, a detailed sensitivity analysis is conducted to demonstrate the reliability of the model. The sensitivity analysis, along with an independent parameter sensitivity method is used to study the impact of individual model parameters on fitting criteria. The results showed higher sensitivity ratio (SR) for the model equation as compared to the sensitivity analysis for a given assumed value of charge transfer coefficient. Also, the fitted curve on experimental data shows nearly same Sum of Squared Residue (SSR) for two kinds of fitting procedures. The 95% confidence intervals for all the fuel cell parameters were presented and analyzed. The ohmic resistance and exchange current density obtained by improved form of model equation were validated by the experimental data in the literature. The deviation and dispersion behavior of important parameters of charge transfer coefficient and ohmic resistance are thoroughly studied for various kinds of variation types, percentage of points and the type of method. Finally, the trends of the sensitivity factor based on the value of model parameter were analyzed. The importance of the present model in obtaining valuable information regarding the fuel cell behavior under different operating conditions is presented. [Display omitted] • A simple semi-empirical method for estimation of kinetic and electric parameters of the fuel cell is developed. • Normal equations and well-defined objective function have been used for fitting. • Experimental I–V curve is used for fitting and EIS-ohmic resistance is utilized for validation. • Sensitivity analysis accompanied with parameter sensitivity method are used to establish the validity of the model and fitting procedure. • Estimation of important fuel cell parameters without resort to sophisticated AC Impedance techniques is a novel feature. [ABSTRACT FROM AUTHOR]

Selecting a safe and clinically beneficial dose can be difficult in drug development. Dose justification often relies on dose-response modeling where parametric assumptions are made in advance which may not adequately fit the data. This is especially problematic in longitudinal dose-response models, where additional parametric assumptions must be made. This paper proposes a class of longitudinal dose-response models to be used in the Bayesian model averaging paradigm which improve trial operating characteristics while maintaining flexibility a priori. A new longitudinal model for non-monotonic longitudinal profiles is proposed. The benefits and trade-offs of the proposed approach are demonstrated through a case study and simulation. [ABSTRACT FROM AUTHOR]

This paper is concerned with the pullback dynamics of a three-dimensional Brinkman-Forchheimer-extended Darcy (3D BFeD) model for porous media in the whole space. The existence and uniqueness of weak solutions is achieved firstly, leading to the generation of a continuous non-autonomous cocycle for the BFed model. Based on the global well-posedness, the existence of pullback attractors is proved by using uniform a priori estimates on the tails of solutions outside bounded domains. [ABSTRACT FROM AUTHOR]

Copyright of Automatisierungstechnik is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Kant-Studien is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposes a novel method for recognizing a set of signals with linearly and nonlinearly included parameters from a given ensemble of signals under essential a priori uncertainty. Due to this uncertainty, well-known statistical methods become inapplicable. Signals may be present in an additive mixture containing an observation noise and a singular interference; the distribution law of the noise is unknown, and only its correlation matrix is specified. The novel method is invariant to this interference, does not require traditional state-space expansion, and ensures the decomposition and parallelization of the computational procedure. The signals and interference are represented using conventional linear spectral decompositions with unknown coefficients and given basis functions. Random and methodological errors, as well as the resulting computational effect, are analyzed. An illustrative example is provided. [ABSTRACT FROM AUTHOR]

In this paper, a new crack surface energy for the simulation of ductile fracture is proposed, which is based on the Allen–Cahn theory of diffuse interfaces. In contrast to existing fracture approaches, here, the crack surface energy density is a double-well potential based on a new interpretation of the crack surface. That is, the energy associated with the whole diffuse region between the fully cracked and intact regions is interpreted as crack surface energy. This kind of formulation, on the one hand, results in the balance of micromechanical forces and on the other hand, is a priori thermodynamically consistent. Furthermore, the proposed formulation is based on a gamma-convergent interface energy and it is in agreement with the classical solution of Irwin (Appl Mech Trans ASME E24:351–369, 1957). It is shown that in contrast to existing models, crack irreversibility is automatically fulfilled and no further constraints related to neither local nor global irreversibility are needed. To also account for potential plastic shear band localization, the approach is extended by a micromorphic plasticity model. By analyzing two different classical numerical benchmark problems, the proposed formulation is shown to enable mesh-independent results which are in agreement with the results of competing approaches. [ABSTRACT FROM AUTHOR]

The aim of this paper is to establish a precise illustration for the structure of the nonconstant steady states for a Beddington–DeAngelis and Tanner predator–prey reaction–diffusion system with prey‐taxis. We treat the nonlinear prey‐taxis as a bifurcation parameter to analyze the bifurcation structure of the system. Furthermore, the exported global bifurcation theorem, under a rather natural condition, offers the existence of nonconstant steady states. In the proof, a priori estimates of steady states will play an important role. The local stability analysis with a numerical simulation and bifurcation analysis are given. Finally, some conclusions including biological meanings are performed to summarize our main analytic results and future investigations. [ABSTRACT FROM AUTHOR]

A new solution strategy for the problem of induction has been developed based on a priori advantages of regret-weighted meta-induction (RW) in prediction tasks. These a priori advantages seem to contradict the no-free lunch (NFL) theorem. In this paper, the NFL challenge is dissolved by three novel results: (1) RW enjoys free lunches in the long run. (2) Yet, the NFL theorem applies to iterated prediction tasks, because the distribution underlying it assigns a zero probability to all possible worlds in which RW enjoys free lunches. (3) The a priori advantages of RW can even be demonstrated for the short run. [ABSTRACT FROM AUTHOR]

This paper concentrates on a priori error estimates of two monolithic schemes for Biot's consolidation model based on the three‐field formulation introduced by Oyarzúa et al. (SIAM J Numer Anal, 2016). The spatial discretizations are based on the Taylor–Hood finite elements combined with Lagrange elements for the three primary variables. We employ two different schemes to discretize the time domain. One uses the backward Euler method, and the other applies the combination of the backward Euler and Crank‐Nicolson methods. A priori error estimates show that both schemes are unconditionally convergent with optimal error orders. Detailed numerical experiments are presented to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

While frameworks to systematically assess bias in systematic reviews and meta-analyses (SRMAs) and frameworks on causal inference are well established, they are less frequently integrated beyond the data analysis stages. This paper proposes the use of Directed Acyclic Graphs (DAGs) in the design stage of SRMAs. We hypothesize that DAGs created and registered a priori can offer a useful approach to more effective and efficient evidence synthesis. DAGs provide a visual representation of the complex assumed relationships between variables within and beyond individual studies prior to data analysis, facilitating discussion among researchers, guiding data analysis, and may lead to more targeted inclusion criteria or set of data extraction items. We illustrate this argument through both experimental and observational case examples. [ABSTRACT FROM AUTHOR]