Journal articles on the topic 'Implicit layers'
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Huang, Zhongzhan, Senwei Liang, Mingfu Liang, and Haizhao Yang. "DIANet: Dense-and-Implicit Attention Network." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 04 (April 3, 2020): 4206–14. http://dx.doi.org/10.1609/aaai.v34i04.5842.
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Attention networks have successfully boosted the performance in various vision problems. Previous works lay emphasis on designing a new attention module and individually plug them into the networks. Our paper proposes a novel-and-simple framework that shares an attention module throughout different network layers to encourage the integration of layer-wise information and this parameter-sharing module is referred to as Dense-and-Implicit-Attention (DIA) unit. Many choices of modules can be used in the DIA unit. Since Long Short Term Memory (LSTM) has a capacity of capturing long-distance dependency, we focus on the case when the DIA unit is the modified LSTM (called DIA-LSTM). Experiments on benchmark datasets show that the DIA-LSTM unit is capable of emphasizing layer-wise feature interrelation and leads to significant improvement of image classification accuracy. We further empirically show that the DIA-LSTM has a strong regularization ability on stabilizing the training of deep networks by the experiments with the removal of skip connections (He et al. 2016a) or Batch Normalization (Ioffe and Szegedy 2015) in the whole residual network.
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Tuval, Israel, Dan Givoli, and Ehud Behar. "Hybrid asymptotic-numerical modeling of thin layers for dynamic thermal analysis of structures." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 3/4 (May 3, 2016): 818–53. http://dx.doi.org/10.1108/hff-11-2014-0336.
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Purpose – The purpose of this paper is to propose a computational model for thin layers, for problems of linear time-dependent heat conduction. The thin layer is replaced by a zero-thickness interface. The advantage of the new model is that it saves the need to construct and use a fine mesh inside the layer and in regions adjacent to it, and thus leads to a reduction in the computational effort associated with implicit or explicit finite element schemes. Design/methodology/approach – Special asymptotic models have been proposed for linear heat transfer and linear elasticity, to handle thin layers. In these models the thin layer is replaced by an interface with zero thickness, and specific jump conditions are imposed on this interface in order to represent the special effect of the layer. One such asymptotic interface model is the first-order Bövik-Benveniste model. In a paper by Sussmann et al., this model was incorporated in a FE formulation for linear steady-state heat conduction problems, and was shown to yield an accurate and efficient computational scheme. Here, this work is extended to the time-dependent case. Findings – As shown here, and demonstrated by numerical examples, the new model offers a cost-effective way of handling thin layers in linear time-dependent heat conduction problems. The hybrid asymptotic-FE scheme can be used with either implicit or explicit time stepping. Since the formulation can easily be symmetrized by one of several techniques, the lack of self-adjointness of the original formulation does not hinder an accurate and efficient solution. Originality/value – Most of the literature on asymptotic models for thin layers, replacing the layer by an interface, is analytic in nature. The proposed model is presented in a computational context, fitting naturally into a finite element framework, with both implicit and explicit time stepping, while saving the need for expensive mesh construction inside the layer and in its vicinity.
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Geiger, Philipp, and Christoph-Nikolas Straehle. "Learning Game-Theoretic Models of Multiagent Trajectories Using Implicit Layers." Proceedings of the AAAI Conference on Artificial Intelligence 35, no. 6 (May 18, 2021): 4950–58. http://dx.doi.org/10.1609/aaai.v35i6.16628.
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For prediction of interacting agents' trajectories, we propose an end-to-end trainable architecture that hybridizes neural nets with game-theoretic reasoning, has interpretable intermediate representations, and transfers to downstream decision making. It uses a net that reveals preferences from the agents' past joint trajectory, and a differentiable implicit layer that maps these preferences to local Nash equilibria, forming the modes of the predicted future trajectory. Additionally, it learns an equilibrium refinement concept. For tractability, we introduce a new class of continuous potential games and an equilibrium-separating partition of the action space. We provide theoretical results for explicit gradients and soundness. In experiments, we evaluate our approach on two real-world data sets, where we predict highway drivers' merging trajectories, and on a simple decision-making transfer task.
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Tierens, Wouter, and Daniel De Zutter. "Implicit Local Refinement for Evanescent Layers Combined With Classical FDTD." IEEE Microwave and Wireless Components Letters 23, no. 5 (May 2013): 225–27. http://dx.doi.org/10.1109/lmwc.2013.2253090.
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Laurent, Gautier. "Iterative Thickness Regularization of Stratigraphic Layers in Discrete Implicit Modeling." Mathematical Geosciences 48, no. 7 (June 14, 2016): 811–33. http://dx.doi.org/10.1007/s11004-016-9637-y.
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Zhao, Huan, Jie Cao, Mingquan Xu, and Jian Lu. "Variational neural decoder for abstractive text summarization." Computer Science and Information Systems 17, no. 2 (2020): 537–52. http://dx.doi.org/10.2298/csis200131012z.
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In the conventional sequence-to-sequence (seq2seq) model for abstractive summarization, the internal transformation structure of recurrent neural networks (RNNs) is completely determined. Therefore, the learned semantic information is far from enough to represent all semantic details and context dependencies, resulting in a redundant summary and poor consistency. In this paper, we propose a variational neural decoder text summarization model (VND). The model introduces a series of implicit variables by combining variational RNN and variational autoencoder, which is used to capture complex semantic representation at each step of decoding. It includes a standard RNN layer and a variational RNN layer [5]. These two network layers respectively generate a deterministic hidden state and a random hidden state. We use these two RNN layers to establish the dependence between implicit variables between adjacent time steps. In this way, the model structure can better capture the complex semantics and the strong dependence between the adjacent time steps when outputting the summary, thereby improving the performance of generating the summary. The experimental results show that, on the text summary LCSTS and English Gigaword dataset, our model has a significant improvement over the baseline model.
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Lin, Baihan. "Regularity Normalization: Neuroscience-Inspired Unsupervised Attention across Neural Network Layers." Entropy 24, no. 1 (December 28, 2021): 59. http://dx.doi.org/10.3390/e24010059.
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Inspired by the adaptation phenomenon of neuronal firing, we propose the regularity normalization (RN) as an unsupervised attention mechanism (UAM) which computes the statistical regularity in the implicit space of neural networks under the Minimum Description Length (MDL) principle. Treating the neural network optimization process as a partially observable model selection problem, the regularity normalization constrains the implicit space by a normalization factor, the universal code length. We compute this universal code incrementally across neural network layers and demonstrate the flexibility to include data priors such as top-down attention and other oracle information. Empirically, our approach outperforms existing normalization methods in tackling limited, imbalanced and non-stationary input distribution in image classification, classic control, procedurally-generated reinforcement learning, generative modeling, handwriting generation and question answering tasks with various neural network architectures. Lastly, the unsupervised attention mechanisms is a useful probing tool for neural networks by tracking the dependency and critical learning stages across layers and recurrent time steps of deep networks.
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Smolarkiewicz, Piotr K., Len G. Margolin, and Andrzej A. Wyszogrodzki. "Implicit Large-Eddy Simulation in Meteorology: From Boundary Layers to Climate." Journal of Fluids Engineering 129, no. 12 (July 21, 2007): 1533–39. http://dx.doi.org/10.1115/1.2801678.
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The dynamics of the atmosphere and oceans pose a severe challenge to the numerical modeler, due in large part to the broad range of scales of length and time that are encompassed. Modern numerical methods based on nonoscillatory finite volume (NFV) approximations provide a simple and effective means for mitigating this challenge by reproducing the large scale behavior of turbulent flows with no need for explicit subgrid-scale models. In this paper, we describe the remarkable properties of a particular NFV model, multidimensional positive definite advection transport algorithm, and highlight its application to a variety of meteorological and turbulent flows.
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Pruett, C. David. "A semi-implicit method for internal boundary layers in compressible flows." Computer Methods in Applied Mechanics and Engineering 137, no. 3-4 (November 1996): 379–93. http://dx.doi.org/10.1016/s0045-7825(96)01074-2.
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Reshniak, Viktor, and Clayton G. Webster. "Robust Learning with Implicit Residual Networks." Machine Learning and Knowledge Extraction 3, no. 1 (December 31, 2020): 34–55. http://dx.doi.org/10.3390/make3010003.
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In this effort, we propose a new deep architecture utilizing residual blocks inspired by implicit discretization schemes. As opposed to the standard feed-forward networks, the outputs of the proposed implicit residual blocks are defined as the fixed points of the appropriately chosen nonlinear transformations. We show that this choice leads to the improved stability of both forward and backward propagations, has a favorable impact on the generalization power, and allows for control the robustness of the network with only a few hyperparameters. In addition, the proposed reformulation of ResNet does not introduce new parameters and can potentially lead to a reduction in the number of required layers due to improved forward stability. Finally, we derive the memory-efficient training algorithm, propose a stochastic regularization technique, and provide numerical results in support of our findings.
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Zografakis, George, and George Barakos. "Implicit CFD methods for transitional shock wave – boundary layer interaction." Aircraft Engineering and Aerospace Technology 88, no. 5 (September 5, 2016): 636–48. http://dx.doi.org/10.1108/aeat-05-2015-0123.
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Purpose This paper aims to explore the potential of transition prediction methods for modelling transitional shock wave/boundary layer interactions. The study is fuelled by the strong interest of researchers and airframe manufacturers in reducing the drag of vehicles flying at transonic speeds. The principle of drag reduction via flow laminarity is valid, provided there is no need for the flow to sustain large pressure gradients or shocks. This is true, as laminar boundary layers are less resistant to flow separation. Design/methodology/approach It is, therefore, worthwhile to assess the performance of CFD methods in modelling laminar boundary layers that can be tripped to turbulent just before an interaction with a shock. In this work, the CFD solver of Liverpool University is used. The method is strongly implicit, and, for this reason, the implementation of intermittency-based models requires special attention. The Navier–Stokes equations, the transport equations of the kinetic energy of turbulence and the turbulent frequency are inverted at the same time as the transport equations for the flow intermittency and the momentum thickness Reynolds number. Findings The result is stable and robust convergence even for complex three-dimensional flow cases. The method is demonstrated for the flow around the V2C section of the TFAST EU, F7 project. The results suggest that the intermittency-based model captures the fundamental physics of the interaction, but verification and validation are needed to ensure that accurate results can be obtained. For this reason, comparisons with the TFAST experiments is put forward as a means of establishing confidence in the transition prediction tools used for shock/boundary layer interaction simulation. Research limitations/implications At the moment, experimental data for transonic transitional buffet are not yet available, although this will change in the near future. Practical implications The required CPU time is neither insignificant not prohibitive for routine computations. Social implications Reducing aircraft drag without compromising on stall characteristics will result in lower fuel consumption and contribute to a greener and more economic flight for passengers. Originality/value To the authors’ knowledge, this is the first time that transitional buffet has been addressed.
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Kwon, O. Key, R. H. Pletcher, and R. A. Delaney. "Solution Procedure for Unsteady Two-Dimensional Boundary Layers." Journal of Fluids Engineering 110, no. 1 (March 1, 1988): 69–75. http://dx.doi.org/10.1115/1.3243513.
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An accurate and reliable solution procedure is presented for solving the two-dimensional, compressible, unsteady boundary layer equations. The procedure solves the governing equations in a coupled manner using a fully implicit finite-difference numerical algorithm. Several unsteady compressible and incompressible laminar flows are considered. Example results for two unsteady incompressible turbulent flows are also included. An algebraic mixing length closure model is used for the turbulent flow calculations. The computed results compare favorably with experimental data and available analytical/numerical solutions.
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Camacho, F. J., G. Guerrero, P. K. Smolarkiewicz, A. G. Kosovichev, and N. N. Mansour. "Exploring shallow sunspot formation by using Implicit Large-eddy simulations." Proceedings of the International Astronomical Union 12, S328 (October 2016): 117–19. http://dx.doi.org/10.1017/s1743921317003921.
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AbstractThe mechanism by which sunspots are generated at the surface of the sun remains unclear. In the current literature two types of explanations can be found. The first one is related to the buoyant emergence of toroidal magnetic fields generated at the tachocline. The second one states that active regions are formed, from initially diffused magnetic flux, by MHD instabilities that develop in the near-surface layers of the Sun. Using the anelastic MHD code EULAG we address the problem of sunspot formation by performing implicit large-eddy simulations of stratified magneto-convection in a domain that resembles the near-surface layers of the Sun. The development of magnetic structures is explored as well as their effect on the convection dynamics. By applying a homogeneous magnetic field over an initially stationary hydrodynamic convective state, we investigate the formation of self-organized magnetic structures in the range of the initial magnetic field strength, 0.01 < B0/Beq < 0.5, where Beq is the characteristic equipartition field strength.
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Ritos, Konstantinos, Ioannis W. Kokkinakis, Dimitris Drikakis, and S. Michael Spottswood. "Implicit large eddy simulation of acoustic loading in supersonic turbulent boundary layers." Physics of Fluids 29, no. 4 (April 2017): 046101. http://dx.doi.org/10.1063/1.4979965.
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APACOGLU-TURAN, Buryan, and Kadir KIRKKOPRU. "Development of Two-Dimensional Thermal Analysis Code for the Analysis of 3D Printed PLA Parts." Eurasia Proceedings of Science Technology Engineering and Mathematics 18 (October 20, 2022): 28–36. http://dx.doi.org/10.55549/epstem.1192316.
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Fused Deposition Modelling is one of the main 3D printing methods to manufacture plastic parts. The strength of the printed part by FDM is dependent on polymer diffusion between printed layers. The polymer diffusion between two neighboring layers occur not only during the extrusion of the hot top layer, but also during the production of consecutive layers due to thermal conduction. The heat diffusion from upper layers enhances the curing of polymers, which consequently affects the strength of the part. Therefore, the history of the temperature variations - curing time and curing temperature - should be analyzed to predict the strength of the part. The goal of this study is to develop a two-dimensional transient thermal analysis solver for the investigation of time-dependent thermal changes during the printing process. This solver is developed with the use of finite difference method employed under implicit scheme. The transient temperature pattern is qualitatively compatible to the experimental results in literature. The solver can be utilized for further thermal analyses to correlate temperature, polymer diffusion and strength with the inclusion of deposition path in the third dimension.
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Christian, Margareta Ingrid. "Aer, Aurae, Venti: Philology and Physiology in Aby Warburg's Dissertation on Botticelli." PMLA/Publications of the Modern Language Association of America 129, no. 3 (May 2014): 399–416. http://dx.doi.org/10.1632/pmla.2014.129.3.399.
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The reception of Aby Warburg's first published work, his dissertation on Sandro Botticelli, has overlooked layers of meaning implicit in Warburg's word choice. His study of the afterlife of antiquity relies on the activation of the semantic afterlives of words such as Inspirator (“inspirer”), Stimmung (“mood,” “atmosphere”), and Milieu (“milieu”). Warburg brings out the reference to air in these words, invoking their philological nuances and physiological contexts. The air designated is not only the physical medium in which Botticelli's windblown accessories move but also the quattrocento's cultural atmosphere in which Botticelli's creativity thrives. In addition, air implicitly functions as a disciplinary trope for the cultural history into which Warburg aimed to extend traditional art history.
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Juang, Hann-Ming Henry. "A Multiconserving Discretization with Enthalpy as a Thermodynamic Prognostic Variable in Generalized Hybrid Vertical Coordinates for the NCEP Global Forecast System." Monthly Weather Review 139, no. 5 (May 2011): 1583–607. http://dx.doi.org/10.1175/2010mwr3295.1.
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A new vertical discretization used in the atmospheric dynamics of the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) is illustrated, with enthalpy as the thermodynamic prognostic variable to reduce computation in thermodynamic equations while concerning all gas tracers in the model. Mass, energy, entropy, and angular momentum conservations are utilized as constraints to discretize the vertical integration with a finite-difference scheme. A specific definition of a generalized hybrid vertical coordinate, including sigma, isobaric, and isentropic surfaces, is introduced to define pressure at the model levels. Vertical fluxes are obtained by the equation of local changes in variables defined for vertical coordinates at all model layers. The forward-weighting semi-implicit time scheme is utilized to eliminate computational noise for stable integration. Because of time splitting between the dynamic and physics processes, the vertical advection is required both in the model dynamics and model physics, and the semi-implicit time scheme is used both in dynamics and after physics computation. Three configurations—sigma, sigma pressure, and sigma entropy—from the specific hybrid vertical coordinates with layer definition similar to NCEP operational GFS have been implemented in the NCEP GFS. Results from the sigma-isentropic coordinate show the largest anomaly correlation and the smallest root-mean-square error in tropical wind among all results at all layers, especially the upper layers. The scores from a period of daily forecast up to 5 days with the sigma-isentropic coordinate show the same level of skill as compared to the NCEP operational GFS. The results from the hurricane tracks for the fall of 2005 with sigma-isentropic coordinates show better scores compared with the operational GFS.
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Parhi, D. R., and M. K. Singh. "Navigational path analysis of mobile robots using an adaptive neuro-fuzzy inference system controller in a dynamic environment." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 224, no. 6 (June 1, 2010): 1369–81. http://dx.doi.org/10.1243/09544062jmes1751.
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This article focuses on the navigational path analysis of mobile robots using the adaptive neuro-fuzzy inference system (ANFIS) in a cluttered dynamic environment. In the ANFIS controller, after the input layer there is a fuzzy layer and the rest of the layers are neural network layers. The adaptive neuro-fuzzy hybrid system combines the advantages of the fuzzy logic system, which deals with explicit knowledge that can be explained and understood, and those of the neural network, which deals with implicit knowledge that can be acquired by learning. The inputs to the fuzzy logic layer include the front obstacle distance, the left obstacle distance, the right obstacle distance, and target steering. A learning algorithm based on the neural network technique has been developed to tune the parameters of fuzzy membership functions, which smooth the trajectory generated by the fuzzy logic system. Using the developed ANFIS controller, the mobile robots are able to avoid static and dynamic obstacles and reach the target successfully in cluttered environments. The experimental results agree well with the simulation results; this proves the authenticity of the theory developed.
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Araya, Guillermo, and Christian Lagares. "Implicit Subgrid-Scale Modeling of a Mach 2.5 Spatially Developing Turbulent Boundary Layer." Entropy 24, no. 4 (April 15, 2022): 555. http://dx.doi.org/10.3390/e24040555.
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We employ numerically implicit subgrid-scale modeling provided by the well-known streamlined upwind/Petrov–Galerkin stabilization for the finite element discretization of advection–diffusion problems in a Large Eddy Simulation (LES) approach. Whereas its original purpose was to provide sufficient algorithmic dissipation for a stable and convergent numerical method, more recently, it has been utilized as a subgrid-scale (SGS) model to account for the effect of small scales, unresolvable by the discretization. The freestream Mach number is 2.5, and direct comparison with a DNS database from our research group, as well as with experiments from the literature of adiabatic supersonic spatially turbulent boundary layers, is performed. Turbulent inflow conditions are generated via our dynamic rescaling–recycling approach, recently extended to high-speed flows. Focus is given to the assessment of the resolved Reynolds stresses. In addition, flow visualization is performed to obtain a much better insight into the physics of the flow. A weak compressibility effect is observed on thermal turbulent structures based on two-point correlations (IC vs. supersonic). The Reynolds analogy (u′ vs. t′) approximately holds for the supersonic regime, but to a lesser extent than previously observed in incompressible (IC) turbulent boundary layers, where temperature was assumed as a passive scalar. A much longer power law behavior of the mean streamwise velocity is computed in the outer region when compared to the log law at Mach 2.5. Implicit LES has shown very good performance in Mach 2.5 adiabatic flat plates in terms of the mean flow (i.e., Cf and UVD+). iLES significantly overpredicts the peak values of u′, and consequently Reynolds shear stress peaks, in the buffer layer. However, excellent agreement between the turbulence intensities and Reynolds shear stresses is accomplished in the outer region by the present iLES with respect to the external DNS database at similar Reynolds numbers.
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Orlić, Milan. "Borislav Pekić’s New textuality in the light of Bakhtin's concept of the open text of the polyphonic novel." Dostoevsky Journal 16, no. 1 (April 25, 2015): 92–107. http://dx.doi.org/10.1163/23752122-01601011.
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In this paper I analyze two of Pekić’s novels in the light of Bakhtin’s concept of the open text of the polyphonic novel which Pekić develops by means of a new Narrator Figure and a new poetics based on an encyclopedic embedded text structure. Among several literary techniques developed from the beginnings of Pekić’s writing, crucial importance belongs to what I call the Explicit Narrator Figure (for instance, in The Time of Miracles, 1965), who speaks in his own voice as interpreter of found texts, and the Implicit Narrator Figure, who adopts the literary and non-literary voices of (many) others, to whose diction and style he assimilates his own voice (for example, in Pilgrimage of Arsenije Njegovan, 1970). This new (postmodern) narrator figure, both explicit and implicit, acts as an interpreter of «found» texts. What connects these two types of Narrator Figures is the document and related Embedded Narration: both narrators thus deal with the pre-texts as well as texts-in-texts, levels and layers of texts, proto-texts and meta-texts – various types of Framed/Embedded Narratives. The Implicit Narrator Figure deals with Biblical witnessed texts and the Explicit Narrator Figure uses personal testamentary texts. In such a way, both Implicit and Explicit Narrator Figures become the researchers of different types of literary and non-literary documents. These complex inter-textual explorations of the “library” of culture are “encyclopedic” in magnitude and reveal, in combination with the new Narrator Figure’s status as Editor and Interpreter, a new type of narrative text, constituted in the encyclopedic open novel structure. Pekić thus introduces a new form of inter-textuality into Serbian literature, implicitly extending Bakhtin’s (and Dostoevsky’s) legacy by drawing on the Serbian national literary canon and the entire Western cultural “library”.
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BUHL, Johannes, Rameez ISRAR, and Markus BAMBACH. "MODELING AND CONVERGENCE ANALYSIS OF DIRECTED ENERGY DEPOSITION SIMULATIONS WITH HYBRID IMPLICIT / EXPLICIT AND IMPLICIT SOLUTIONS." Journal of Machine Engineering 19, no. 3 (September 15, 2019): 95–108. http://dx.doi.org/10.5604/01.3001.0013.4086.
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Conventional metal manufacturing techniques are suitable for mass production. However, cheaper and faster alternatives are preferred for small batch sizes and individualized components. Directed energy deposition (DED) processes allow depositing metallic material in almost arbitrary shapes. They are characterized by cyclic heat input, hence heating and cooling every point in the workpiece several times. This temperature history leads to distribution of mechanical properties, distortions, residual stresses or even fatigue properties in the part. To avoid experimental trial-and-error optimization, different methods are available to simulate DED processes. Currently, the wire arc additive manufacturing (WAAM) is the most competitive DED process. In this work, a simulation method for the WAAM process is established and validated, which should be capable to calculate global effects (e.g. distortions, residual stresses) of real WAAM-processes with duration of hours and thousands of weld beads. The addition of beads and layers is simulated by the element birth and death technique. The elements are activated according to the movements of the heat source (arc). In this paper, the influence of the time step, the mesh size and the material properties of the inactive elements in hybrid implicit / explicit and fully implicit solutions are evaluated with respect to the computation time and stability. This investigation concludes several recommendations for AM-modelling. For example, a low Young’s modulus (100 N/mm²) for the inactive elements show nearly no influences on the welding simulation, but introduces numerical instabilities in case of multiple welding beads. The Young’s modulus should be increased to 1.000 N/mm² for small mesh-sizes, small step-sizes and many beads, even when it introduces unwanted stresses.
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Weller, Hilary, and Ava Shahrokhi. "Curl-Free Pressure Gradients over Orography in a Solution of the Fully Compressible Euler Equations with Implicit Treatment of Acoustic and Gravity Waves." Monthly Weather Review 142, no. 12 (December 1, 2014): 4439–57. http://dx.doi.org/10.1175/mwr-d-14-00054.1.
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Abstract Steep orography can cause noisy solutions and instability in models of the atmosphere. A new technique for modeling flow over orography is introduced that guarantees curl-free gradients on arbitrary grids, implying that the pressure gradient term is not a spurious source of vorticity. This mimetic property leads to better hydrostatic balance and better energy conservation on test cases using terrain-following grids. Curl-free gradients are achieved by using the covariant components of velocity over orography rather than the usual horizontal and vertical components. In addition, gravity and acoustic waves are treated implicitly without the need for mean and perturbation variables or a hydrostatic reference profile. This enables a straightforward description of the implicit treatment of gravity waves. Results are presented of a resting atmosphere over orography and the curl-free pressure gradient formulation is advantageous. Results of gravity waves over orography are insensitive to the placement of terrain-following layers. The model with implicit gravity waves is stable in strongly stratified conditions, with NΔt up to at least 10 (where N is the Brunt–Väisälä frequency). A warm bubble rising over orography is simulated and the curl-free pressure gradient formulation gives much more accurate results for this test case than a model without this mimetic property.
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Siddiqa, Sadia, Naheed Begum, S. Noor, and Md Anwar Hossain. "Marangoni Convection Flow Along a Wavy Surface with Non-Linear Radiation." International Journal of Nonlinear Sciences and Numerical Simulation 20, no. 5 (August 27, 2019): 517–25. http://dx.doi.org/10.1515/ijnsns-2016-0120.
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AbstractA boundary-layer analysis is presented for steady, two-dimensional, Marangoni convection along an irregular surface. Thick radiation limit is considered to express the radiative heat flux. A coordinate transformation is adopted to convert the physical domain into computational domain. Implicit finite difference method is then used to obtain the solutions of the problem. The main purpose of this study is to demonstrate the radiation effects on the dissipative layers. Numerical solutions are presented in the form of skin friction coefficient, heat transfer coefficient, velocity and temperature profiles, streamlines and isotherms. It is observed that thermal radiation has a pronounced effect on the flow field and amplitude of the harmonic oscillations also decay with $R_d$. The momentum and thermal boundary-layer thickness increases as $R_d$ gets augmented.
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Gama Goicochea, Armando. "A Model for the Stability of a TiO2 Dispersion." ISRN Materials Science 2013 (August 26, 2013): 1–9. http://dx.doi.org/10.1155/2013/547608.
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A computational study of a colloidal dispersion stabilized with grafted polymer layers is presented here as a model for white, water-based paints. The interaction model includes repulsive, three-body interactions and attractive van der Waals forces. The electrostatic interactions are also studied. Stability criteria can be established for the dispersion, such as the thickness of the adsorbed polymer layers, and the quality of the solvent. Using implicit solvent molecular dynamics calculations, the spatial distribution of the pigments is obtained through the calculation of the radial distribution functions. The results show that the solvent quality and the thickness of the grafted polymer layer are key variables in the stability of the dispersion. Additionally, a structural phase transition is predicted, which is driven by the pigment concentration in the dispersion. It is argued that the predictions of this work are useful guidelines in the design of paints and coatings of current industrial interest.
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An, Si-Qi, Hai-Lin Zou, and Zi-Chen Deng. "A dielectric elastomer membrane integrated with protective passive layers under explicit and implicit prestretch." International Journal of Mechanics and Materials in Design 16, no. 4 (June 3, 2020): 733–48. http://dx.doi.org/10.1007/s10999-020-09499-6.
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Stella, John A., and Michael S. Sacks. "On the Biaxial Mechanical Properties of the Layers of the Aortic Valve Leaflet." Journal of Biomechanical Engineering 129, no. 5 (February 22, 2007): 757–66. http://dx.doi.org/10.1115/1.2768111.
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All existing constitutive models for heart valve leaflet tissues either assume a uniform transmural stress distribution or utilize a membrane tension formulation. Both approaches ignore layer specific mechanical contributions and the implicit nonuniformity of the transmural stress distribution. To begin to address these limitations, we conducted novel studies to quantify the biaxial mechanical behavior of the two structurally distinct, load bearing aortic valve (AV) leaflet layers: the fibrosa and ventricularis. Strip biaxial tests, with extremely sensitive force sensing capabilities, were further utilized to determine the mechanical behavior of the separated ventricularis layer at very low stress levels. Results indicated that both layers exhibited very different nonlinear, highly anisotropic mechanical behaviors. While the leaflet tissue mechanical response was dominated by the fibrosa layer, the ventricularis contributed double the amount of the fibrosa to the total radial tension and experienced four times the stress level. The strip biaxial test results further indicated that the ventricularis exhibited substantial anisotropic mechanical properties at very low stress levels. This result suggested that for all strain levels, the ventricularis layer is dominated by circumferentially oriented collagen fibers, and the initial loading phase of this layer cannot be modeled as an isotropic material. Histological-based thickness measurements indicated that the fibrosa and ventricularis constitute 41% and 29% of the total layer thickness, respectively. Moreover, the extensive network of interlayer connections and identical strains under biaxial loading in the intact state suggests that these layers are tightly bonded. In addition to advancing our knowledge of the subtle but important mechanical properties of the AV leaflet, this study provided a comprehensive database required for the development of a true 3D stress constitutive model for the native AV leaflet.
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Qin, Libo, Wanxiang Che, Yangming Li, Mingheng Ni, and Ting Liu. "DCR-Net: A Deep Co-Interactive Relation Network for Joint Dialog Act Recognition and Sentiment Classification." Proceedings of the AAAI Conference on Artificial Intelligence 34, no. 05 (April 3, 2020): 8665–72. http://dx.doi.org/10.1609/aaai.v34i05.6391.
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In dialog system, dialog act recognition and sentiment classification are two correlative tasks to capture speakers' intentions, where dialog act and sentiment can indicate the explicit and the implicit intentions separately (Kim and Kim 2018). Most of the existing systems either treat them as separate tasks or just jointly model the two tasks by sharing parameters in an implicit way without explicitly modeling mutual interaction and relation. To address this problem, we propose a Deep Co-Interactive Relation Network (DCR-Net) to explicitly consider the cross-impact and model the interaction between the two tasks by introducing a co-interactive relation layer. In addition, the proposed relation layer can be stacked to gradually capture mutual knowledge with multiple steps of interaction. Especially, we thoroughly study different relation layers and their effects. Experimental results on two public datasets (Mastodon and Dailydialog) show that our model outperforms the state-of-the-art joint model by 4.3% and 3.4% in terms of F1 score on dialog act recognition task, 5.7% and 12.4% on sentiment classification respectively. Comprehensive analysis empirically verifies the effectiveness of explicitly modeling the relation between the two tasks and the multi-steps interaction mechanism. Finally, we employ the Bidirectional Encoder Representation from Transformer (BERT) in our framework, which can further boost our performance in both tasks.
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Yusifova, Pustakhanim. "Three Layers of Pragmatic Failure Across Languages and Cultures." International Journal of English Linguistics 8, no. 6 (September 2, 2018): 256. http://dx.doi.org/10.5539/ijel.v8n6p256.
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Recently, cultural, economical, and political relations between nations have increased in a noticeable way. People communicate and interact more and more to achieve mutual understanding and hit the target. While communicating, different language users may not understand or misunderstand intentions of their interlocutors. This misunderstanding happens due to the different lexicon used in different linguistic communities that reflect their lifestyle. Some words possess culture-specific meanings that reflect not only ways of living of a certain society but also the way the members of that society think and act. For this reason, intentionally or unintentionally, people apply their native language competence to the foreign language that will likely result in misunderstanding known as pragmatic failure. This article deals with the pragmatic failure on word, sentence and discourse levels. Here, implicit meanings of lexical and grammatical elements in discourses across languages and cultures, namely in the English, Azerbaijani, as well as Russian, Chinese, Turkish, and Korean languages and cultures have been investigated.
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Kaposi, Dávid. "On the possibility of critiquing Israel: The Times’ engagement with Israel’s deployment of white phosphorous during the first Gaza war." Media, War & Conflict 9, no. 3 (July 31, 2016): 272–89. http://dx.doi.org/10.1177/1750635216653904.
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This article comprises a discourse analysis of The Times’ (the British daily newspaper) coverage of Israeli deployment of white phosphorous during the first Gaza war. It argues that this issue is of special theoretical importance as it demonstrates a rare instance of a medium that is considered supportive of an agent (i.e. the state of Israel) offering apparently substantial criticism of that particular agent. The article progresses by uncovering layers of the newspaper’s coverage. It starts by introducing some quantitative characteristics, then moves on to analysis proper – explicit arguments and implicit meaning in editorials. In doing this, the author argues that an understanding of the discourse around criticism and the Israeli–Palestinian conflict needs to account not just for overt arguments but implicit meanings which, consciously or not, are sustaining those arguments.
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Kuria, Isaac M., and Peter E. Raad. "An Implicit Multidomain Spectral Collocation Method for the Simulation of Gas Bearings Between Textured Surfaces." Journal of Tribology 118, no. 4 (October 1, 1996): 783–93. http://dx.doi.org/10.1115/1.2831609.
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This work presents an implicit, multidomain, Chebyshev spectral collocation method for the solution of the compressible Reynolds equation of lubrication for a self-acting air bearing supporting a taper-flat slider. The method maintains second-order accuracy in time and exponential accuracy in space. Multiple domains are introduced to allow for the distribution of additional collocation points in the boundary layer regions without increasing the number of collocation points everywhere else in the computational domain. Multiple domains are also used to resolve individual sinusoidal roughness waves, demonstrating the method’s utility in resolving geometric and/or flow features in the interior of the computational domain. The ordinary differential equations governing the slider’s two degrees of freedom are integrated in time by the use of a fourth-order Adams-Bashforth method which allows for accurate and efficient coupling with the fluid dynamics of the gas bearing. The strength of the multidomain pseudospectral method in resolving problems with important geometric features and boundary layers is demonstrated by numerical experiments for sliders possessing different taper lengths and surface textures.
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Bonaventura, Luca, Enrique D. Fernández-Nieto, José Garres-Díaz, and Gladys Narbona-Reina. "Multilayer shallow water models with locally variable number of layers and semi-implicit time discretization." Journal of Computational Physics 364 (July 2018): 209–34. http://dx.doi.org/10.1016/j.jcp.2018.03.017.
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CHEN, CHIUN-CHUAN, TAI-PING LIU, and TONG YANG. "EXISTENCE OF BOUNDARY LAYER SOLUTIONS TO THE BOLTZMANN EQUATION." Analysis and Applications 02, no. 04 (October 2004): 337–63. http://dx.doi.org/10.1142/s0219530504000400.
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In this paper, we consider the existence of boundary layer solutions to the Boltzmann equation for a hard potential with angular cut-off. The boundary condition is imposed for incoming particles of Dirichlet type and the solution tends to a global Maxwellian in the far field. Similar to the problem on the hard sphere model studied in [17], the existence of a solution is shown to depend on the Mach number of the far field Maxwellian, and there is an implicit solvability conditions yielding the co-dimensions of the boundary data. For hard potential models, the shape of the boundary layers is richer. This compels the introduction of a new norm which is a function of both position and velocity.
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Gromyko, G., M. Chuiko, A. Smychnik, A. Hrechka, and A. Zlebava. "Mathematical Modeling of Geofiltration and Geomigration Processes in Multilayer Systems." Computational Methods in Applied Mathematics 7, no. 2 (2007): 163–77. http://dx.doi.org/10.2478/cmam-2007-0009.
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AbstractNumerical methods for simultaneous solution of geofiltration and ge- omigration problems in multilayer systems in contaminant transport investigation have been developed. A multilayer system consists of several aquifers separated by weakly permeable layers. Mathematical models are constructed under the following assump- tion: longitudinal flows predominate in the aquifer and crossflows — in the separation layers. The mass transfer is described by the convection and diffusion equations. The implicit finite volume difference schemes were used. The computational al- gorithm is based on the concept of splitting the schemes on physical processes of two- dimensional filtration and contaminant transport along aquifers and vertical transport through the separation levels. An iterative method of the block Gauss — Seidel type for the realization of implicit finite difference schemes for geofiltration and geomigration problems in the presence of wells and contaminant sources has been constructed. The method is based on the perturbation transfer from cells with sources (wells and sources of contaminant). The iterative process for update of unknowns has been constructed taking into account the position of a cell relative to the calculated cells. The results of the numerical experiment on modeling groundwater flows redistri- bution and contaminant migration in system of two aquifers with operating wells are presented.
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Yan, H., D. Knight, and A. A. Zheltovodov. "Large-Eddy Simulation of Supersonic Flat-Plate Boundary Layers Using the Monotonically Integrated Large-Eddy Simulation (MILES) Technique." Journal of Fluids Engineering 124, no. 4 (December 1, 2002): 868–75. http://dx.doi.org/10.1115/1.1516578.
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A supersonic flat-plate boundary layer at a Reynolds number of 2×104 based on the inflow boundary layer thickness is investigated at different Mach numbers (M=2.88 and 4) using the monotonically integrated large-eddy simulation (MILES) technique. The inherent numerical dissipation is taken as an implicit subgrid scales (SGS) model to close the Favre-filtered compressible Navier-Stokes (NS) equations. A finite volume method with second-order accuracy in time and space is implemented for the solution of the Navier-Stokes equations on an unstructured grid of tetrahedra. The heat transfer coefficient is predicted by simulating both adiabatic and isothermal cases. The mean flowfield and turbulent stresses are in good agreement with experiment. The relationship between the predicted skin friction coefficient and heat transfer coefficient is in close agreement with the Reynolds analogy factor. The variation of turbulent Prandtl number cross the boundary layer falls within the experimental envelope. These are the first LES predictions of adiabatic and isothermal supersonic flat plate boundary layers using the MILES technique.
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Hulstijn, Jan. "Towards a unified account of the representation, processing and acquisition of second language knowledge." Second Language Research 18, no. 3 (July 2002): 193–223. http://dx.doi.org/10.1191/0267658302sr207oa.
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This article argues for the need to reconcile symbolist and connectionist accounts of (second) language learning by propounding nine claims, aimed at integrating accounts of the representation, processing and acquisition of second language (L2) knowledge. Knowledge representation is claimed to be possible both in the form of symbols and rules and in the form of networks with layers of hidden units representing knowledge in a distributed, subsymbolic way. Implicit learning is the construction of knowledge in the form of such networks. The strength of association between the network nodes changes in the beginning stages of learning with accumulating exposure, following a power law (automatization). Network parts may attain the status equivalent to ‘symbols’. Explicit learning is the deliberate construction of verbalizable knowledge in the form of symbols (concepts) and rules. The article argues for a nonnativist, emergentist view of first language learning and adopts its own version of what could be called a non-interface position in L2 learning: although explicit knowledge cannot turn into implicit knowledge through practice, it is argued that explicit learning and practice often form efficient ways of mastering an L2 by creating opportunities for implicit learning.
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Lubkov, M. V., and O. O. Zakharchuk. "Modeling of oil phase displacement processes in heterogeneous anisotropic reservoirs." Geofizicheskiy Zhurnal 43, no. 3 (July 28, 2021): 170–80. http://dx.doi.org/10.24028/gzh.v43i3.236387.
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Methods of computer modeling of slightly permeable anisotropic oil-bearing layers are needed nowadays because they give us a possibility to obtain a concept on filtration processes near producing and forcing wells in different practical situations and in this way to raise the level of exploitation of such layers significantly. On the other hand, they allow evaluation and taking into account some uncertainties which appear as a result of inefficient information on the structure and properties of the layer outside the wells. In order to investigate the practical aspects of supporting efficiency of oil production in anisotropic heterogeneous low permeable reservoirs on the base of combined finite-element-difference method for solving the non-stationary anisotropic piezoconductivity problem, modeling of distribution of layer pressure was carried out in the vicinity of the production and forcing wells taking into account the anisotropy of the permeability and conditions of the oil phase infiltration on the margins of the examined layer. It has been found that the intensity of filtration process between producing and forcing wells depends essentially on their spacing in both shear-isotropic and anisotropic oil-bearing layers. In addition the effect of oil phase permeability in shear direction dominates over the effect of permeability in axes directions. Starting from the obtained information for the effective exploitation of anisotropic slightly permeable layers we need to locate producing and forcing wells in the areas with relatively low permeability of the layer and especially to avoid the places with presence of shear permeability. It is important to locate the wells in such a way that blocking the oil in the direction of reduced permeability and fast depletion of the layer in the direction of increased permeability would not happen as well as mutual exchange between producing and forcing wells would not stop. While locating the system of specified wells within anisotropic layers of oil deposit it is necessary to conduct a systemic analysis of environmental anisotropy of layers aimed at such a location of these wells which would guarantee the effective dynamics of filtration processes around them. Application of quadratic isoparametric approximation of finite-elemental net of examined area of oil-bearing layer and implicit differential time approximation brings to increase of precision and stability of numerical solution of the problem.
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Schatz, Andreas, Gabriel Willmann, M. Dominik Fischer, Kai Schommer, André Messias, Eberhart Zrenner, Karl-Ulrich Bartz-Schmidt, and Florian Gekeler. "Electroretinographic assessment of retinal function at high altitude." Journal of Applied Physiology 115, no. 3 (August 1, 2013): 365–72. http://dx.doi.org/10.1152/japplphysiol.00245.2013.
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Although hypoxia plays a key role in the pathophysiology of many common and well studied retinal diseases, little is known about the effects of high-altitude hypoxia on retinal function. The aim of the present study was to assess retinal function during exposure to high-altitude hypoxia using electroretinography (ERG). This work is related to the Tübingen High Altitude Ophthalmology (THAO) study. Electroretinography was performed in 14 subjects in Tübingen, Germany (341 m) and at high altitude at La Capanna Regina Margherita, Italy (4,559 m) using an extended protocol to assess functional integrity of various retinal layers. To place findings in the context of acute mountain sickness, correlations between ERG measurements and oxygen saturation, heart rate, and scores of acute mountain sickness (AMS) were calculated. At high altitude, the maximum response of the scotopic sensitivity function, the implicit times of the a- and b-wave of the combined rod-cone responses, and the implicit times of the photopic negative responses (PhNR) were significantly altered. A-wave slopes and i-waves were significantly decreased at high altitude. The strongest correlation was found for PhNR and O2 saturation ( r = 0.68; P < 0.05). Of all tested correlations, only the photopic b-wave implicit time (10 cd·s/m2) was significantly correlated with severity of AMS ( r = 0.57; P < 0.05). ERG data show that retinal function of inner, outer, and ganglion cell layer is altered at high-altitude hypoxia. Interestingly, the most affected ERG parameters are related to combined rod-cone responses, which indicate that phototransduction and visual processing, especially under conditions of rod-cone interaction, are primarily affected at high altitude.
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Wang, Qian, Shinan Wang, Rong Shi, and Yong Li. "A Power Transformer Fault Diagnosis Method Based on Random Vector Functional-Link Neural Network." Mathematical Problems in Engineering 2021 (March 20, 2021): 1–18. http://dx.doi.org/10.1155/2021/6656061.
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The random vector functional link (RVFL) network is suitable for solving nonlinear problems from transformer fault symptoms and different fault types due to its simple structure and strong generalization ability. However, the RVFL network has a disadvantage in that the network structure, and parameters are basically determined by experiences. In this paper, we proposed a method to improve the RVFL neural network algorithm by introducing the concept of hidden node sensitivity, classify each hidden layer node, and remove nodes with low sensitivity. The simplified network structure could avoid interfering nodes and improve the global search capability. The five characteristic gases produced by transformer faults are divided into two groups. A fault diagnosis model of three layers with four classifiers was built. We also investigated the effects of the number of hidden nodes and scale factors on RVFL network learning ability. Simulation results show that the number of implicit layer nodes has a large impact on the network model when the number of input dimensions is small. The network requires a higher number of implicit layer neurons and a smaller threshold range. The size of the scale factor has significant influence on the network model with larger input dimension. This paper describes the theoretical basis for parameter selection in RVFL neural networks. The theoretical basis for the selection of the number of hidden nodes, and the scale factor is derived. The importance of parameter selection for the improvement of diagnostic accuracy is verified through simulation experiments in transformer fault diagnosis.
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Hu, Ya-Yuan, Wan-Huan Zhou, and Yuan-Qiang Cai. "Large-strain elastic viscoplastic consolidation analysis of very soft clay layers with vertical drains under preloading." Canadian Geotechnical Journal 51, no. 2 (February 2014): 144–57. http://dx.doi.org/10.1139/cgj-2013-0200.
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A very soft clay layer is highly compressible and exhibits significant creep under loading. The classical linearly elastic constitutive relationship and small-strain assumption are not suitable for the consolidation analysis of very soft clays. This paper presents a new large-strain consolidation model that incorporates the Yin–Graham elastic viscoplastic (EVP) constitutive equation for use in studying the consolidation of very soft clay layers with vertical drains under preloading. First, the large-strain fluid continuity equation and the EVP constitutive equation are incorporated into a quadratic differential equation of pore-water pressure and its integral terms. Second, the alternating-direction implicit (ADI) method and virtual node method are adopted to obtain the finite difference solution. A computer program named “BSSDS” is developed for large-strain EVP consolidation analysis of clay layers with vertical drains, taking into account the complicated in situ conditions, such as resistance of vertical drains, smear effects, variation of permeability with void ratio, and multilayered soils. Third, the new large-strain numerical method is applied to the consolidation modeling of very soft clay layers with vertical drains under preloading at a site that is part of the Hong Kong – Shenzhen Western Corridor Link Project. It is found that the foundation settlements of the new large-strain EVP consolidation model have good agreement with the measured data. Finally, three different consolidation models are used to calculate the average degree of consolidation and settlements of the clay layers. The analysis shows that it is essential to consider both large-strain compression and creep effects in the analysis of very soft clay layers with vertical drains under loading.
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Han, Sang-Jin, Young-Hee Shim, and Young-Do Park. "Cosmopolitan Sociology and Confucian Worldview: Beck’s Theory in East Asia." Theory, Culture & Society 33, no. 7-8 (November 9, 2016): 281–90. http://dx.doi.org/10.1177/0263276416672535.
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This article aims at an active dialogue between Ulrich Beck and East Asia with respect to cosmopolitan imagination. Beck’s cosmopolitan sociology requires a reflective cosmopolitan publicness to cope with various kinds of global risks. We therefore extract three different layers of publicness from neo-Confucianism – survival-oriented, deliberative, and ecological – and argue that Beck’s cosmopolitan vision can be better conceptualized when properly linked to, or founded upon, the Tianxiaweigong normative potentials of neo-Confucianism. In so doing our intention is to make Beck’s implicit (Asian) sensibilities and the implicit Asian (cosmopolitan) orientations explicit, as a double process of cosmopolitan self-reflection and dialogue. We also draw attention to the analysis of the cosmopolitan actor in East Asia. Finally, we note that the cosmopolitan future of East Asia still remains uncertain and that reconciling global risk politics, national interests and cosmopolitan morality presents a big challenge to second modern transformation.
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Dolgikh, Tatiana F. "Hodograph Method for Solving the Problem of Shallow Water Under a Solid Lid." UNIVERSITY NEWS. NORTH-CAUCASIAN REGION. NATURAL SCIENCES SERIES, no. 1 (209) (March 31, 2021): 15–24. http://dx.doi.org/10.18522/1026-2237-2021-1-15-24.
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One of the mathematical models describing the behavior of two horizontally infinite adjoining layers of an ideal incompressible liquid under a solid cover moving at different speeds is investigated. At a large difference in the layer velocities, the Kelvin-Helmholtz instability occurs, which leads to a distortion of the interface. At the initial point in time, the interface is not necessarily flat. From a mathematical point of view, the behavior of the liquid layers is described by a system of four quasilinear equations, either hyperbolic or elliptic, in partial derivatives of the first order. Some type shallow water equations are used to construct the model. In the simple version of the model considered in this paper, in the spatially one-dimensional case, the unknowns are the boundary between the liquid layers h(x,t) and the difference in their velocities γ(x,t). The main attention is paid to the case of elliptic equations when |h|<1 and γ>1. An evolutionary Cauchy problem with arbitrary sufficiently smooth initial data is set for the system of equations. The explicit dependence of the Riemann invariants on the initial variables of the problem is indicated. To solve the Cauchy problem formulated in terms of Riemann invariants, a variant of the hodograph method based on a certain conservation law is used. This method allows us to convert a system of two quasilinear partial differential equations of the first order to a single linear partial differential equation of the second order with variable coefficients. For a linear equation, the Riemann-Green function is specified, which is used to construct a two-parameter implicit solution to the original problem. The explicit solution of the problem is constructed on the level lines (isochrons) of the implicit solution by solving a certain Cauchy problem for a system of ordinary differential equations. As a result, the original Cauchy problem in partial derivatives of the first order is transformed to the Cauchy problem for a system of ordinary differential equations, which is solved by numerical methods. Due to the bulkiness of the expression for the Riemann-Green function, some asymptotic approximation of the problem is considered, and the results of calculations, and their analysis are presented.
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Harun, Zawati, Nazri Mohd Nawi, Mohd Faizal Batcha, and David Gethin. "Modeling of Layering Ceramic Shell Mould." Applied Mechanics and Materials 232 (November 2012): 548–52. http://dx.doi.org/10.4028/www.scientific.net/amm.232.548.
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This paper presents the modeling the drying process of shell mould layering process for the ceramic shell mould fabrication process. As this process involves the repeated drying of the different wetted/saturated layers, therefore modeling of this phenomena involve a sequent approach to tackle the whole development of shell mould layering process. In this work an Ab-Initia approach was selected as the best simulation technique to map the drying mechanism. Saturation or moisture content was selected as the best parameter that will represent the drying of layering process. Using FEM with quadrilateral shape mapping of several interested points were selected to predict the moisture/saturation movement during the drying of shell layering stages. Standard drying time with 2 hours and early drying time were chosen to measure the moisture movement as layer added to the previous dried coated shell or layers. This complex mechanism of drying and penetration layering shell were then numerically solve with fully implicit backward time stepping scheme. Hopefully, this model and can be used to measure the complex movement of the main parameter i.e saturation/temperature in the drying process of multilayer system which is sometimes impossible directly measured under experimental technique
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Natarajan, N., and G. Suresh Kumar. "Numerical modelling of colloidal transport in fractured porous media with double layered fracture-skin." Journal of Geo-Engineering Sciences 1, no. 2 (2014): 83–94. http://dx.doi.org/10.3233/jgs-130016.
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A numerical model is developed for studying the transport of colloids in a coupled fracture-matrix system with double layer fracture-skin. The governing equations describing colloid transport along the fracture and diffusion into fracture-skin layers as well as rock-matrix, normal to the fracture axis are coupled with each other. The coupled non linear equations are solved numerically with fully implicit finite difference method. Sensitivity analysis is performed to investigate the effect of various colloid properties on the colloid concentration in the multiple porosity fractured system. Colloid remobilisation and filtration has been accounted in the model. Results suggest that the inclusion of a second fracture-skin layer has a marginal effect on the transport mechanism of colloids. As colloid velocity increases, the diffusion of colloids into the fracture-skin decreases due to the low residence time available for the colloids. High first layer fracture-skin thickness and porosity enhances the diffusion of colloids from the aqueous phase of the fracture into the skin considerably resulting in low colloidal concentration within the fracture. Variation in the porosity as well as thickness of the second layer of the fracture-skin has negligible effect on the colloidal concentration in the fracture. The colloid transport mechanism in fractured porous media is marginally affected by the multiple porosity system, or in other words additional layers of fracture skin. High filtration coefficient and low remobilisation coefficient result in low colloidal concentration within the fracture.
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Singh, R. K., K. Jagannadham, and J. Narayan. "Laser surface modification of metal-coated ceramics." Journal of Materials Research 3, no. 6 (December 1988): 1119–26. http://dx.doi.org/10.1557/jmr.1988.1119.
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Pulsed excimer laser radiation has been successfully employed in the improvement (> 50%) of fracture strength of metal-coated ceramics. Thin metallic layers (∼500 Å) of nickel were deposited on silicon nitride and silicon carbide substrates and further irradiated with pulsed excimer (xenon chloride, krypton fluoride) laser pulses. The laser energy density was varied from 0.4 to 2.0 J cm −2 to optimize the formation of mixed interfacial layers. The formation of interfacial layers was studied by transmission electron microscopy and Rutherford backscattering spectrometry techniques. Detailed heat flow calculations using implicit finite difference methods were performed to simulate the effects of intense laser irradiation on metal-coated ceramic structures. Three different mechanisms were found to play an important role in the improvement in the fracture strength of these ceramics. Theoretical calculations showed that the displacement of the crack tip away from the free surface by laser surface modification can lead to a 100% improvement in the fracture strength of the ceramic.
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Yin, Pei, Jing Wang, Jun Zhao, Huan Wang, and Hongcheng Gan. "Deep Collaborative Filtering: A Recommendation Method for Crowdfunding Project Based on the Integration of Deep Neural Network and Collaborative Filtering." Mathematical Problems in Engineering 2022 (July 21, 2022): 1–15. http://dx.doi.org/10.1155/2022/4655030.
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In real recommendation systems, implicit feedback data is more common and easier to obtain, and recommendation algorithms based on such data will be more applicable. However, implicit feedback data cannot directly express user preferences. Meanwhile, data sparsity caused by massive data is still an urgent problem to be solved in recommendation system. In response to this phenomenon, this paper proposes a deep collaborative filtering algorithm. In the perspective of implicit feedback, this method uses the advantages of convolutional neural network for effective learning of the nonlinear interaction of users and items and the characteristics of collaborative filtering algorithm for modeling the linear interaction of users and items and combines the two methods for recommendation. Finally, the baseline method is set up and the comparative experiment and parameter adjustment is carried out. The experimental results show that the proposed algorithm has significantly improved the recommendation accuracy on public dataset (Yahoo! Movie). The parameter adjustment results show that, under the condition of uniformly collecting negative feedback data and setting a certain number of convolution layers, the sparser the data is, the better the recommendation performs. As a result, this paper has made some progress in solving the problem of data sparsity and enriching the research of recommendation system.
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Acosta., Carlos Egas, Felipe Gil-Castiñeira, Enrique Costa-Montenegro, and Jorge Sá Silva. "Reliable Link Level Routing Algorithm in Pipeline Monitoring Using Implicit Acknowledgements." Sensors 21, no. 3 (February 1, 2021): 968. http://dx.doi.org/10.3390/s21030968.
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End-to-end reliability for Wireless Sensor Network communications is usually provided by upper stack layers. Furthermore, most of the studies have been related to star, mesh, and tree topologies. However, they rarely consider the requirements of the multi-hop linear wireless sensor networks, with thousands of nodes, which are universally used for monitoring applications. Therefore, they are characterized by long delays and high energy consumption. In this paper, we propose an energy efficient link level routing algorithm that provides end-to-end reliability into multi-hop wireless sensor networks with a linear structure. The algorithm uses implicit acknowledgement to provide reliability and connectivity with energy efficiency, low latency, and fault tolerance in linear wireless sensor networks. The proposal is validated through tests with real hardware. The energy consumption and the delay are also mathematically modeled and analyzed. The test results show that our algorithm decreases the energy consumption and minimizes the delays when compared with other proposals that also apply the explicit knowledge technique and routing protocols with explicit confirmations, maintaining the same characteristics in terms of reliability and connectivity.
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Iannella, Renato. "Towards E-Society Policy Interoperability for Social Web Networks." International Journal of E-Adoption 2, no. 1 (January 2010): 13–29. http://dx.doi.org/10.4018/jea.2010010102.
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The move toward Policy-Oriented Web is destined to provide support for policy expression and management in the core web layers. One of the most promising areas that can drive this new technology adoption is e-Society communities. With so much user-generated content being shared by these social networks, there is the real danger that the implicit sharing rules that communities have developed over time will be lost in translation in the new digital communities. This will lead to a corresponding loss in confidence in e-Society sites. The Policy-Oriented Web attempts to turn the implicit into the explicit with a common framework for policy language interoperability and awareness. This paper reports on the policy driving factors from the Social Networks experiences using real-world use cases and scenarios. In particular, the key functions of policy-awareness—for privacy, rights, and identity—will be the driving force that enables the e-Society to appreciate new interoperable policy regimes.
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Rubin, Barry, and W. Lloyd Buchanan. "A General Purpose Thermal Model." Society of Petroleum Engineers Journal 25, no. 02 (April 1, 1985): 202–14. http://dx.doi.org/10.2118/11713-pa.
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Abstract This paper describes a fully implicit four-phase (oil, water, gas, solid fuel) numerical reservoir model for simulating hot water injection, steam injection, dry combustion, and wet combustion in one, two, or three dimensions and in either a Cartesian, radial, or curvilinear geometry. The simulator rigorously models fluid flow, heat transfer (convective and conductive), heat loss to formation, fluid vaporization/condensation, and chemical reactions. Any number of oil or gas phase components may be specified, along with any number of solid phase components (fuel and catalysts). The simulator employs either D4 Gaussian elimination or powerful incomplete factorization methods to solve the often poorly conditioned matrix problems. An implicit well model is coupled to the simulator, where reservoir unknowns and well block pressures are primary variables. This paper includescomparisons of the numerical model's results with previously reported laboratory physical models' results for steam and combustion and physical models' results for steam and combustion andanalytical solutions to a hot waterflood problem. In addition, an actual field-scale history match is presented for a single-well steam stimulation problem. Introduction Recent papers by Crookston et al., Youngren Rubin and Vinsome, and Coats have outlined the current trend in thermal process simulation. The trend has been the development of more implicit, more comprehensive finite-difference simulators. Youngren describes a model based on a highly implicit steam model. The components representing air and combustion gases are treated explicitly. Burning reactions are handled not through rates but through the assumption of 100% oxygen utilization at the combustion front. Crookston et al. describe a linearized implicit combustion model that can describe the reaction of a predetermined set of gases and oils. Both of these models are predetermined set of gases and oils. Both of these models are multidimensional and do not handle wellbore-reservoir coupling fully implicitly. Rubin and Vinsome describe a fully implicit one-dimensional (ID) combustion tube simulator. Coats 4 describes a fully implicit four-phase multicomponent multidimensional combustion simulator. This model is general in nature except for the wellbore-reservoir coupling. This work describes a general, fully implicit, four-phase, multicomponent, multidimensional steam and combustion simulator that includes a fully implicit well model and a suite of powerful iterative techniques that can be used for the solution of large-scale thermal problems. The following sections of this paper describe the model's fluid and energy flow equations, property package, powerful iterative techniques capable of reliable package, powerful iterative techniques capable of reliable use with steam and combustion problems, fully implicit well model, and equation substitution formulation. Further, a section considering the applications of the model is presented. Mathematical Model The simulator ISCOM rigorously models fluid flow, vaporization/condensation phenomena, and heat transfer and is efficient enough to allow the simulation of realistically large reservoir problems. The formulation allows for any number of chemical components and reactions. The components can exist in any of four phases: oil, water, gas, or solid. A reaction also can occur in any of the above phases. Furthermore, water and any of the oil components can vaporize. The simulator development is based on the following assumptions.The model can operate in one, two, or three dimensions (1D, 2D, or 3D) with variable grid spacing.Cartesian, radial, non-Cartesian (variable-thickness grids), and specific curvilinear grids corresponding to the commonly used well patterns can be used. patterns can be used.The number of components existing in each phase is variable, and the components can be distributed among four phases.The number and type of chemical reactions can be varied.Each layer, well, or block in the reservoir can exhibit different properties (e.g., viscosities, relative permeabilities, and properties (e.g., viscosities, relative permeabilities, and compressibilities) at different times.Wells can operate under specified fluid rates or flowing pressures and are subject to a hierarchy of user-specified constraints.The simulator must be reasonably efficient to handle field-scale simulation economically, without sacrificing accuracy. Grid Generation The model defines a block-centered grid system in 1-, 2-, or 3D, normally based on Cartesian xyz coordinates. Radial geometries are accommodated by internal modification of the gridblock volumes and interblock transmissibilities. For rectangular grids with variable thickness layers, the interblock transmissibilities and gravity head terms are derived from gridblock dimensions and depth from reference. Curvilinear grids are generated by the method of conformal transformation, which yields analytical formulae for potential and stream functions. Two simple patterns are considered: one-eighth of a five-spot and one-eighth of a nine-spot. SPEJ P. 202
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Bacellar-Galdino, Marianna, Fabiano Montiani-Ferreira, Andre Tavares Somma, Ricardo Guilherme D'Otaviano de Castro Vilani, and Ivan Roque de Barros Filho. "Ophthalmic findings in sheep treated with closantel in Curitiba, Brazil." May-2020 13, no. 5 (2020): 860–64. http://dx.doi.org/10.14202/vetworld.2020.860-864.
Full textAbstract:
Background and Aim: Closantel is a widely used anti-parasitic drug that is known to cause ophthalmic problems that lead to blindness. The aim of this study was to investigate the possible electroretinographic changes in sheep that received closantel. Materials and Methods: Twenty-four 30-day-old Suffolk sheep were split into control group (12 animals) and closantel group (12 animals). The latter group received 15 mg/kg of closantel subcutaneously immediately after the first electroretinography (ERG). The ISCEV protocol was used to perform the ERGs pre-dose (0), 7, and 30 days after treatment. Statistical analyses to compare ERG responses using t-test and analysis of variance were performed (p<0.05). Three months later, the animals were euthanized and the eyes and a part of optic nerve were collected for histopathology. Photography of the retina and optic nerve was taken, and measures of the retinal layers were made and analyzed by paired t-test. Results: Closantel group showed a significant increase of the mean scotopic a-wave amplitude from 0 to 7 days after closantel administration, using a stimulus of 10,000 mcd.s/m2 and a decrease of the mean scotopic and photopic a-wave amplitude (from 7 to 30 days) using the same flash intensity, as well as a decrease in mean photopic b-wave amplitude (from 7 to 30 days) within the group. Control group showed a significant increase of the mean scotopic b-wave implicit time from pre to 30 days after treatment and an increase of the mean scotopic a-wave implicit time from pre to 7 days after treatment, with the stimulus of 10,000 mcd.s/m2. This group also showed a decrease in mean photopic b-wave implicit time (from pre to 30 days after treatment), using a stimulus of 10,000 mcd.s/m2 and a decrease in mean photopic a-wave implicit time from pre to 30 days after treatment, using a stimulus of 3000 mcd.s/m2. The no difference was found in images neither in the measurements of the retina layers. Conclusion: As observed by ERG responses and the histopathology, a dose of 15 mg/kg of closantel does not significantly affect retinal and optic nerve structures in sheep but the electroretinographic results, however, showed alterations on the phototransduction.
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Couvidat, F., and K. Sartelet. "The Secondary Organic Aerosol Processor (SOAP v1.0) model: a unified model with different ranges of complexity based on the molecular surrogate approach." Geoscientific Model Development 8, no. 4 (April 22, 2015): 1111–38. http://dx.doi.org/10.5194/gmd-8-1111-2015.
Full textAbstract:
Abstract. In this paper the Secondary Organic Aerosol Processor (SOAP v1.0) model is presented. This model determines the partitioning of organic compounds between the gas and particle phases. It is designed to be modular with different user options depending on the computation time and the complexity required by the user. This model is based on the molecular surrogate approach, in which each surrogate compound is associated with a molecular structure to estimate some properties and parameters (hygroscopicity, absorption into the aqueous phase of particles, activity coefficients and phase separation). Each surrogate can be hydrophilic (condenses only into the aqueous phase of particles), hydrophobic (condenses only into the organic phases of particles) or both (condenses into both the aqueous and the organic phases of particles). Activity coefficients are computed with the UNIFAC (UNIversal Functional group Activity Coefficient; Fredenslund et al., 1975) thermodynamic model for short-range interactions and with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) parameterization for medium- and long-range interactions between electrolytes and organic compounds. Phase separation is determined by Gibbs energy minimization. The user can choose between an equilibrium representation and a dynamic representation of organic aerosols (OAs). In the equilibrium representation, compounds in the particle phase are assumed to be at equilibrium with the gas phase. However, recent studies show that the organic aerosol is not at equilibrium with the gas phase because the organic phases could be semi-solid (very viscous liquid phase). The condensation–evaporation of organic compounds could then be limited by the diffusion in the organic phases due to the high viscosity. An implicit dynamic representation of secondary organic aerosols (SOAs) is available in SOAP with OAs divided into layers, the first layer being at the center of the particle (slowly reaches equilibrium) and the final layer being near the interface with the gas phase (quickly reaches equilibrium). Although this dynamic implicit representation is a simplified approach to model condensation–evaporation with a low number of layers and short CPU (central processing unit) time, it shows good agreements with an explicit representation of condensation–evaporation (no significant differences after a few hours of condensation).