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1
Burlakov, Evgenii O., та Ivan N. Malkov. "On connection between continuous and discontinuous neural field models with microstructure: II. Radially symmetric stationary solutions in 2D (“bumps”)". Russian Universities Reports. Mathematics, № 129 (2020): 6–17. http://dx.doi.org/10.20310/2686-9667-2020-25-129-6-17.
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We suggest a method allowing to investigate existence and the measure of proximity between the stationary solutions to continuous and discontinuous neural fields with microstructure. The present part involves results on proximity of the stationary solutions to specific homogenized neural field equations with continuous and discontinuous activation functions. The results of numerical investigation of radially symmetric stationary solutions (bumps) to the neural field with a discontinuous activation function and a given microstructure are presented.
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Sun, Chao Ming. "Recovery Techniques for Complex Grain Boundaries." Applied Mechanics and Materials 364 (August 2013): 854–58. http://dx.doi.org/10.4028/www.scientific.net/amm.364.854.
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When estimating the grain size, the processing effect for complex grain boundaries is often poor. To solve this problem, the recovery techniques for complex grain boundary are studied. After analysis of steps to estimate the grain size, we know that it is critical to get more accurate boundary before quantitative determination, and the discontinuous points among grain boundaries should be connected. Therefore, two methods to connect the discontinuous points were established, and it showed that watershed method is more efficient; however over-segmentation and under-segmentation exist. Accordingly, recovery techniques of complex grain boundary were put forward, that is to edit the regional minimum manually or to connect the discontinuous points in the gray image before watershed transform. By this technique, the grain boundary can be got more accurately, conveniently and continuously closed, independently of interfere of noise, scratches, illumination etc.
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Gaussier, Hervé, and Xianghong Gong. "Smooth Equivalence of Deformations of Domains in Complex Euclidean Spaces." International Mathematics Research Notices 2020, no. 18 (2018): 5578–610. http://dx.doi.org/10.1093/imrn/rny168.
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Abstract We prove that two smooth families of 2-connected domains in $\mathbf{C}$ are smoothly equivalent if they are equivalent under a possibly discontinuous family of biholomorphisms. We construct, for $\infty > m \geq 3$, two smooth families of smoothly bounded $m$-connected domains in $\mathbf{C}$, and for $n\geq 2$, two families of strictly pseudoconvex domains in $\mathbf{C}^n$, which are equivalent under discontinuous families of biholomorphisms but not under any continuous family of biholomorphisms. Finally, we give sufficient conditions for the smooth equivalence of two smooth families of domains.
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Kumar, Gautam, and Mayuresh V. Kothare. "On the Continuous Differentiability of Inter-Spike Intervals of Synaptically Connected Cortical Spiking Neurons in a Neuronal Network." Neural Computation 25, no. 12 (2013): 3183–206. http://dx.doi.org/10.1162/neco_a_00503.
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We derive conditions for continuous differentiability of inter-spike intervals (ISIs) of spiking neurons with respect to parameters (decision variables) of an external stimulating input current that drives a recurrent network of synaptically connected neurons. The dynamical behavior of individual neurons is represented by a class of discontinuous single-neuron models. We report here that ISIs of neurons in the network are continuously differentiable with respect to decision variables if (1) a continuously differentiable trajectory of the membrane potential exists between consecutive action potentials with respect to time and decision variables and (2) the partial derivative of the membrane potential of spiking neurons with respect to time is not equal to the partial derivative of their firing threshold with respect to time at the time of action potentials. Our theoretical results are supported by showing fulfillment of these conditions for a class of known bidimensional spiking neuron models.
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Liu, Heng, Jie Hong, and Dayi Zhang. "Bending and vibration of a discontinuous beam with a curvic coupling under different axial forces." Frontiers of Mechanical Engineering 15, no. 3 (2020): 417–29. http://dx.doi.org/10.1007/s11465-019-0584-4.
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Abstract The transverse stiffness and vibration characteristics of discontinuous beams can significantly differ from those of continuous beams given that an abrupt change in stiffness may occur at the interface of the former. In this study, the equations for the deflection curve and vibration frequencies of a simply supported discontinuous beam under axial loads are derived analytically on the basis of boundary, continuity, and deformation compatibility conditions by using equivalent spring models. The equation for the deflection curve is solved using undetermined coefficient methods. The normal function of the transverse vibration equation is obtained by separating variables. The differential equations for the beam that consider moments of inertia, shearing effects, and gyroscopic moments are investigated using the transfer matrix method. The deflection and vibration frequencies of the discontinuous beam are studied under different axial loads and connection spring stiffness. Results show that deflection decreases and vibration frequencies increase exponentially with increasing connection spring stiffness. Moreover, both variables remain steady when connection spring stiffness reaches a considerable value. Lastly, an experimental study is conducted to investigate the vibration characteristics of a discontinuous beam with a curvic coupling, and the results exhibit a good match with the proposed model.
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Ferreira, Carina Fonseca, Dina D’Ayala, Jose L. Fernandez Cabo, and Rafael Díez. "Numerical Modelling of Historic Vaulted Timber Structures." Advanced Materials Research 778 (September 2013): 517–25. http://dx.doi.org/10.4028/www.scientific.net/amr.778.517.
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Historic timber structures forming vaulted roofs of public and ecclesiastical buildings are present worldwide. The structural response of these constructions is usually governed by the structural performance of the joints, the interaction between the timber structure and the masonry parts, and the current condition of both joints and timber members. At present, numerical approaches, such as finite element method-based approaches are well-established tools for investigating the global response of complex historic structures. Using a FE-based software package, the authors developed a numerical model of a portion of an existing historic vaulted timber structure, which is part of the roof of the Cathedral of Ica in Peru, considering the in-plane semi-rigid response of the planked arches in the elastic range. For this purpose, the rotational and shear stiffness of the joints and the properties of the materials, which are assumed in good conditions, are calibrated by comparing the numerical outputs with experimental results available in literature. The aim of the work presented here is to compare the response of the same vault assuming either continuous (planks continuously connected) or discontinuous arches (modelling of the semi-rigid response of the joints which connect the planks together).
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Sakai, Taku, and Hiromi Miura. "Annealing of Deformed Materials Developed by Continuous/Discontinuous Dynamic Recrystallization." Materials Science Forum 550 (July 2007): 327–32. http://dx.doi.org/10.4028/www.scientific.net/msf.550.327.
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Annealing behaviour was studied in deformed copper developed by continuous or discontinuous dynamic recrystallization (cDRX or dDRX). Pure copper was deformed to large strains by multi-directional forging at room temperature, resulting in an ultra-fine grained structure due to operation of cDRX. Subsequent annealing of such a fine-grained copper can be controlled mainly by grain growth accompanied with recovery and no texture change, that is continuous static recrystallization (cSRX). On the other hand, 4 kinds of static restoration processes operate during annealing of dDRXed copper, i.e. metadaynamic recovery and recystallization (mDRV and mDRX), and classical static recovery and recrystallization. The stable existence of mDRVed grains containing moderate dislocations leads to incomplete recrystallization even after a long period of annealing time. It is discussed how such various types of annealing processes, occurring in cDRXed or dDRXed matrices, can be connected with the characteristic nature of the deformed microstructures.
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Burlakov, E. O., and M. A. Nasonkina. "On connection between continuous and discontinuous neural field models with microstructure I. General theory." Tambov University Reports. Series: Natural and Technical Sciences 23, no. 121 (2018): 17–30. http://dx.doi.org/10.20310/1810-0198-2018-23-121-17-30.
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CHEN, B., Q. YUAN, J. H. FAN, J. G. WANG, and J. LUO. "FIBER-CONTINUOUS PILLAR-BOARD BIOCOMPOSITE STRUCTURE IN TUMBLEBUG ELYTRA." International Journal of Modern Physics B 24, no. 01n02 (2010): 191–200. http://dx.doi.org/10.1142/s0217979210064125.
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The observation of scanning electron microscope (SEM) showed that Tumblebug elytra consist of almost parallel upper and lower cuticles. Both of which are a kind of chitin-fiber-reinforced composite. There is a kind of chitin-fiber-reinforced composite pillars between the upper and lower cuticles, which support and connect the upper and lower cuticles uprightly. More careful observation showed that the chitin fibers in the pillars smoothly extend to the upper and lower composite cuticles forming a kind of fiber-continuous pillar-board composite (FCPBC) structure. Based on the observation, two kinds of pillar-board composite structure specimens, respective with continuous and discontinuous glass fibers, were fabricated with molding and felting processes. The rupture strengths of the two kinds of the specimens were tested and compared. It showed that the rupture strength of the specimens of the FCPBC structure is markedly larger than that of the specimens of the fiber-discontinuous pillar-board composite (FDPBC) structure. At last, the experimental result was analyzed for illumining the mechanism of the FCPBC structure in the enhancement of the strength.
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Arancio, M., C. Marchetti, G. Landi, et al. "A Rare Case of Female Splenogonadal Fusion." Urologia Journal 76, no. 2 (2009): 137–39. http://dx.doi.org/10.1177/039156030907600221.
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Splenogonadal fusion (SGF) is a rare congenital abnormality in which there is a fusion between spleen and gonad. Approximately 150 cases have been described in world literature. SGF can be continuous, where there is a connection between ectopic and orthotopic spleen, and discontinuous, with no connection. In our paper we report a case of SGF in a 36-year-old female with ultrasound and MR findings of space-occupying lesion in lower abdomen, and a review of the literature.
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Demirci, Emrah, Xiao Nan Hou, Memiş Acar, Behnam Pourdeyhimi, and Vadim V. Silberschmidt. "Numerical Modelling of Thermally Bonded Nonwovens: Continuous and Discontinuous Approaches." Solid State Phenomena 188 (May 2012): 164–69. http://dx.doi.org/10.4028/www.scientific.net/ssp.188.164.
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Nonwoven fabrics are web structures of randomly-oriented fibres, bonded by means of mechanical, thermal or chemical techniques. This paper focuses on nonwovens manufactured with polymer-based fibres and bonded thermally. During thermal bonding of such fibres, as a hot calender with an engraved pattern contacts the fibre web, bond spots are formed by melting of the polymer material. As a result of this bonding process, a pattern of bond points connected with randomly oriented polymer-based fibres form the nonwoven web. Due to their manufacturing-induced composite microstructure and random orientation of fibres, nonwovens demonstrate a complex mechanical behaviour. Two distinct modelling approaches were introduced to simulate the non-trivial mechanical response of thermally bonded nonwovens based on their planar density. The first modelling approach was developed to simulate the mechanical behaviour of high-density nonwovens, and the respective fabric was modelled with shell elements with thicknesses identical to those of the bond points and the fibre matrix having distinct anisotropic mechanical properties. Random orientation of individual fibres was introduced into the model in terms of the orientation distribution function in order to determine the material’s anisotropy. The second modelling approach was introduced to simulate low-density nonwovens, and it treated the nonwoven media as a structure composed of fibres acting as truss links between bond points.
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Liu, F. L., and K. M. Liew. "Vibration Analysis of Discontinuous Mindlin Plates by Differential Quadrature Element Method." Journal of Vibration and Acoustics 121, no. 2 (1999): 204–8. http://dx.doi.org/10.1115/1.2893965.
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A new numerical technique, the differential quadrature element method (DQEM), has been developed for solving the free vibration of the discontinuous Mindlin plate in this paper. By the DQEM, the complex plate domain is decomposed into small simple continuous subdomains (elements) and the differential quadrature method (DQM) is applied to each continuous subdomain to solve the problems. The detailed formulations for the DQEM and the connection conditions between each element are presented. Several numerical examples are analyzed to demonstrate the accuracy and applicability of this new method to the free vibration analysis of the Mindlin plate with various discontinuities which are not solvable directly using the differential quadrature method.
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Okuda, Takayuki. "Homogeneous space with non-virtually abelian discontinuous groups but without any proper SL(2, ℝ)-action". International Journal of Mathematics 27, № 03 (2016): 1650018. http://dx.doi.org/10.1142/s0129167x1650018x.
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In the study of discontinuous groups for non-Riemannian homogeneous spaces, the idea of “continuous analogue” gives a powerful method (T. Kobayashi [Math. Ann. 1989]). For example, a semisimple symmetric space [Formula: see text] admits a discontinuous group which is not virtually abelian if and only if [Formula: see text] admits a proper [Formula: see text]-action (T. Okuda [J. Differ. Geom. 2013]). However, the action of discrete subgroups is not always approximated by that of connected groups. In this paper, we show that the theorem cannot be extended to general homogeneous spaces [Formula: see text] of reductive type. We give a counterexample in the case [Formula: see text].
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Fahem, Kawther, Dhia Elhak Chariag, and Lassaad Sbita. "Performance evaluation of continuous and discontinuous pulse width modulation techniques for grid-connected PWM converter." International Transactions on Electrical Energy Systems 28, no. 10 (2018): e2609. http://dx.doi.org/10.1002/etep.2609.
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Ion, Stelian, Dorin Marinescu, and Stefan-Gicu Cruceanu. "Riemann Problem for Shallow Water Equation with Vegetation." Analele Universitatii "Ovidius" Constanta - Seria Matematica 26, no. 2 (2018): 145–73. http://dx.doi.org/10.2478/auom-2018-0023.
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Abstract We investigate the existence of the solution of the Riemann Problem for a simplified water ow model on a vegetated surface - system of shallow water type equations. It is known that the system with discontinuous topography is non-conservative even if the porosity is absent. A system with continuous topography and discontinuous porosity is also non-conservative. In order to define Riemann solution for such systems, it is necessary to introduce a family of paths that connects the states defining the Riemann Problem. We focus our attention towards choosing such a family based on physical arguments. We provide the structure of the solution for such Riemann Problems.
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Cupal, Jan, Stephan Kopp, and Peter F. Stadler. "RNA Shape Space Topology." Artificial Life 6, no. 1 (2000): 3–23. http://dx.doi.org/10.1162/106454600568294.
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The distinction between continuous and discontinuous transitions is a long-standing problem in the theory of evolution. Because continuity is a topological property, we present a formalism that treats the space of phenotypes as a (finite) topological space, with a topology that is derived from the probabilities with which one phenotype is accessible from another through changes at the genotypic level. The shape space of RNA secondary structures is used to illustrate this approach. We show that evolutionary trajectories are continuous if and only if they follow connected paths in phenotype space.
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Behrens, Bernd Arno, A. Erman Tekkaya, Klaus Georg Kosch, Annika Foydl, Matthias Kammler, and Andreas Jäger. "Manufacturing of Steel-Reinforced Aluminum Parts by Co-Extrusion and Subsequent Forging." Key Engineering Materials 585 (December 2013): 149–56. http://dx.doi.org/10.4028/www.scientific.net/kem.585.149.
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The processes of manufacturing continuously and discontinuously steel-reinforced aluminum profiles by means of co-extrusion and subsequent forging were examined. In the co-extrusion and subsequent forging of discontinuously reinforced parts, influences of the reinforcing elements on forming behavior and material bonding for both processes were investigated. It was shown that forming temperature as well as ram speed have no influence on joining quality and forming behavior of the reinforcing elements in the co-extrusion of continuously reinforced profiles. The analyses of the joining zone between the composite partners revealed that a good connection of the two materials could be achieved.
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Jonuzi, Asmir, Nusret Popović, Zlatan Zvizdić, et al. "A rare case of discontinuous type splenogonadal fusion in a 13 year old boy: a case report and review of literature." International Surgery Journal 7, no. 10 (2020): 3438. http://dx.doi.org/10.18203/2349-2902.isj20204150.
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Splenogonadal fusion (SGF) is a rare developmental anomaly in which an abnormal connection between the splenic tissue and gonads or mesonephric derivatives is present. This entity often presents with scrotal mass, inguinal hernia, or cryptorchidism. Less than 200 cases have been reported since it was first described in 1883. It can be of continuous and discontinuous type based on the presence of a band of connecting splenic tissue. Report a rare case of discontinuous type of SGF in an adolescent male presenting as nonpalpable testis. On evaluation, ultrasonography (USG) and magnetic resonance imaging of abdomen and pelvis, his left scrotal testis was atrophied and right intra-abdominal undescended testis. This is the first reported case of SGF from Bosnia and Herzegovina. Laparoscopy was demonstrated to be the only accurate exploratory procedure for the diagnosis and surgical treatment of SGF with non‑palpable testis.
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PANAGIOTOU, KONSTANTINOS, RETO SPÖHEL, ANGELIKA STEGER, and HENNING THOMAS. "Explosive Percolation in Erdős–Rényi-Like Random Graph Processes." Combinatorics, Probability and Computing 22, no. 1 (2012): 133–45. http://dx.doi.org/10.1017/s0963548312000442.
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The study of the phase transition of random graph processes, and recently in particular Achlioptas processes, has attracted much attention. Achlioptas, D'Souza and Spencer (Science, 2009) gave strong numerical evidence that a variety of edge-selection rules in Achlioptas processes exhibit a discontinuous phase transition. However, Riordan and Warnke (Science, 2011) recently showed that all these processes have a continuous phase transition.In this work we prove discontinuous phase transitions for three random graph processes: all three start with the empty graph on n vertices and, depending on the process, we connect in every step (i) one vertex chosen randomly from all vertices and one chosen randomly from a restricted set of vertices, (ii) two components chosen randomly from the set of all components, or (iii) a randomly chosen vertex and a randomly chosen component.
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Simpson, David J. W. "Unfolding Codimension-Two Subsumed Homoclinic Connections in Two-Dimensional Piecewise-Linear Maps." International Journal of Bifurcation and Chaos 30, no. 03 (2020): 2030006. http://dx.doi.org/10.1142/s0218127420300062.
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For piecewise-linear maps, the phenomenon that a branch of a one-dimensional unstable manifold of a periodic solution is completely contained in its stable manifold is codimension-two. Unlike codimension-one homoclinic corners, such “subsumed” homoclinic connections can be associated with stable periodic solutions. The purpose of this paper is to determine the dynamics near a generic subsumed homoclinic connection in two dimensions. Assuming the eigenvalues associated with the periodic solution satisfy [Formula: see text], in a two-parameter unfolding there exists an infinite sequence of roughly triangular regions within which the map has a stable single-round periodic solution. The result applies to both discontinuous and continuous maps, although these cases admit different characterizations for the border-collision bifurcations that correspond to boundaries of the regions. The result is illustrated with a discontinuous map of Mira and the two-dimensional border-collision normal form.
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Feng, Z., and Xun Chen. "Grinding Wheel Loading Features Extracted by Image Processing." Key Engineering Materials 304-305 (February 2006): 14–18. http://dx.doi.org/10.4028/www.scientific.net/kem.304-305.14.
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The paper presents a method that identifies and extracts features of chips on loading grinding wheel using image processing technology. The Sobel operator is adopted to detect chips edge. The segmenting threshold was obtained by applying Otsu's method. Image dilation connects the discontinuous segments to yield continuous and close shapes of chips. Erosion removes the noise from the image. The different optical characters between metal chips and abrasive grains are analysed. The ratios of chips are calculated and displayed to monitor the wheel surface working status. The toolbox of the MATLAB is used for image processing.
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Chen, Huann-Sheng, Sarah Zeichner, Robert N. Anderson, David K. Espey, Hyune-Ju Kim, and Eric J. Feuer. "The Joinpoint-Jump and Joinpoint-Comparability Ratio Model for Trend Analysis with Applications to Coding Changes in Health Statistics." Journal of Official Statistics 36, no. 1 (2020): 49–62. http://dx.doi.org/10.2478/jos-2020-0003.
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AbstractAnalysis of trends in health data collected over time can be affected by instantaneous changes in coding that cause sudden increases/decreases, or “jumps,” in data. Despite these sudden changes, the underlying continuous trends can present valuable information related to the changing risk profile of the population, the introduction of screening, new diagnostic technologies, or other causes. The joinpoint model is a well-established methodology for modeling trends over time using connected linear segments, usually on a logarithmic scale. Joinpoint models that ignore data jumps due to coding changes may produce biased estimates of trends. In this article, we introduce methods to incorporate a sudden discontinuous jump in an otherwise continuous joinpoint model. The size of the jump is either estimated directly (the Joinpoint-Jump model) or estimated using supplementary data (the Joinpoint-Comparability Ratio model). Examples using ICD-9/ICD-10 cause of death coding changes, and coding changes in the staging of cancer illustrate the use of these models.
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Horvath, Kristian, Yuh-Lang Lin, and Branka Ivančan-Picek. "Classification of Cyclone Tracks over the Apennines and the Adriatic Sea." Monthly Weather Review 136, no. 6 (2008): 2210–27. http://dx.doi.org/10.1175/2007mwr2231.1.
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Abstract Cyclones that appear in the Adriatic Sea basin strongly influence the climate and weather conditions in the area. In particular, apart from the usually mild climate, cyclone activity in the Adriatic and the central Mediterranean Sea provide both the main hydrological forcing and the trigger mechanisms for a range of extreme weather phenomena. Therefore, a basic understanding of the cyclogenesis over the Adriatic Sea is essential. In particular, the classification of different types of cyclogenesis in the area is fundamental because it will help the understanding and prediction of the relevant weather phenomena. In this study, based on the analysis of the 4-yr (2002–05) operational European Centre for Medium-Range Weather Forecasts T511 dataset, various types of cyclone tracks are classified and the mesocyclogenesis areas in the vicinity of the Adriatic Basin are isolated. This analysis indicates that the following four types of cyclogenesis over the Adriatic Sea can be identified: 1) type A: cyclones connected with preexisting Genoa cyclones [with two subcategories, (A-I) continuous track: Genoa cyclones crossing over the Apennines to the Adriatic Sea, and (A-II) discontinuous track: new surface cyclones generated over the Adriatic Sea under the influence of a parent cyclone generated in the Gulf of Genoa (Genoa cyclones) and moving toward the Adriatic but blocked by the Apennines]; 2) type B: cyclones developed in situ over the Adriatic Sea without any connections with other preexisting cyclones in the surrounding area; 3) type AB: mixed types A and B cyclones, including cases where two cyclones coexist and stride over the Apennines (twin or eyeglass cyclones); and 4) type C: cyclones moving from the Mediterranean Sea, but not from the Gulf of Genoa (non-Genoa cyclones) [with 2 subcategories: (C-I) continuous track: a non-Genoa cyclone is able to cross over the Apennines to the Adriatic Sea continuously, and (C-II) discontinuous track: a non-Genoa cyclone is blocked by the Apennines and a new surface cyclone is generated over the Adriatic Sea]. The relevant dynamics of the above types of cyclones are discussed along with characteristics of the cyclones and their synoptic situations at the lower and upper troposphere.
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Beer, Gerald. "Topological Completeness of Function Spaces Arising in the Hausdorff Approximation of Functions." Canadian Mathematical Bulletin 35, no. 4 (1992): 439–48. http://dx.doi.org/10.4153/cmb-1992-058-1.
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AbstractLet X be a complete metric space. Viewing continuous real functions on X as closed subsets of X × R, equipped with Hausdorff distance, we show that C(X, R) is completely metrizable provided X is complete and sigma compact. Following the Bulgarian school of constructive approximation theory, a bounded discontinuous function may be identified with its completed graph, the set of points between the upper and lower envelopes of the function. We show that the space of completed graphs, too, is completely metrizable, provided X is locally connected as well as sigma compact and complete. In the process, when X is a Polish space, we provide a simple answer to the following foundational question: which subsets of X × R arise as completed graphs?
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Albalawi, Hani, and Sherif Zaid. "An H5 Transformerless Inverter for Grid Connected PV Systems with Improved Utilization Factor and a Simple Maximum Power Point Algorithm." Energies 11, no. 11 (2018): 2912. http://dx.doi.org/10.3390/en11112912.
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Due to their small size, minimum cost, and great efficiency, photovoltaic (PV) grid-connected transformerless inverters have been developed and become famous around the world in distributed PV generators systems. One of the most efficient topologies of the transformerless inverter family is H5 topology. This inverter extracts a discontinuous current from the PV panel, which conflicts with the operation at maximum power point tracking (MPPT) conditions while the utilization factor of the PV degrades. This paper proposes improved H5 topology featuring a boost converter inserted in the middle between the PV panels and the H5 inverter. The design of the boost converter is planned to operate at continuous conduction mode to guarantee MPPT conditions of the PV. A new and simple off line MPPT algorithm is introduced and performance factors like efficiency and utilization factors of the proposed and convention H5 topology are compared. The simulation results indicate that the proposed system provides a preferable utilization factor and a simpler MPPT algorithm.
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Li, Qiyu, Hongwei Zhou, Jiansong Zhang, Shengdun Zhao, and Jingfeng Lu. "A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM." Energies 13, no. 7 (2020): 1595. http://dx.doi.org/10.3390/en13071595.
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The output LC filter of a photovoltaic (PV) string three-level grid-tied inverter that connects the filter capacitor neutral point to dc-link capacitor neutral point can reduce the common-mode (CM) current injected to the grid by letting the CM current circulate within the inverter. However, the internal CM current may resonate because of the existence of the resonant frequency of the internal CM LC circuit. Compared with the traditional continuous pulse-width modulation (CPWM), the resonance can be worse if discontinuous pulse-width modulation (DPWM) is applied, for the zero sequence quantity of DPWM contains more harmonics than that of CPWM. In this paper, a virtual negative resistor based common mode current resonance suppression method for a three-level grid-tied inverter is proposed to overcome the CM current resonance problem in DPWM application. Different positions of the virtual negative resistor in the equivalent CM circuit with different feedback variables are analyzed theoretically. The virtual negative resistor connected in series with the inductor in the equivalent CM circuit is selected to damp the CM current resonance for simplification and damping performance. Different from the implementation in CPWM where a pair of small voltage vectors exist and are used to adjust the CM voltage directly, the proposed method for DPWM application is implemented indirectly by adding the CM adjustment quantity to differential-mode (DM) control quantity with appropriate coefficients. Depending on the sector of DM control quantity in the α β reference frame, the coefficients are calculated using one of three specific voltage vectors. Experimental results are given to demonstrate the effectiveness of theoretical analyses and the proposed method.
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Becher, Simon, and Gunar Matthies. "Variational time discretizations of higher order and higher regularity." BIT Numerical Mathematics 61, no. 3 (2021): 721–55. http://dx.doi.org/10.1007/s10543-021-00851-6.
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AbstractWe consider a family of variational time discretizations that are generalizations of discontinuous Galerkin (dG) and continuous Galerkin–Petrov (cGP) methods. The family is characterized by two parameters. One describes the polynomial ansatz order while the other one is associated with the global smoothness that is ensured by higher order collocation conditions at both ends of the subintervals. Applied to Dahlquist’s stability problem, the presented methods provide the same stability properties as dG or cGP methods. Provided that suitable quadrature rules of Hermite type are used to evaluate the integrals in the variational conditions, the variational time discretization methods are connected to special collocation methods. For this case, we present error estimates, numerical experiments, and a computationally cheap postprocessing that allows to increase both the accuracy and the global smoothness by one order.
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Cao, Taiqiang, Fang You, Fei Zhang, Ping Yang, Qian Luo, and Jun Wang. "DSP-Based Control of Tri-State Boost PFC Converter with High Input Power Factor for Wide Range of Load Variations." Journal of Circuits, Systems and Computers 24, no. 05 (2015): 1550072. http://dx.doi.org/10.1142/s0218126615500723.
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Tri-state boost power factor correction (PFC) converter operating in pseudo-continuous-conduction mode (PCCM) is analyzed in this paper. The connection of power switch in parallel with inductor makes the boost converter operate in PCCM, which provides an additional degree of control freedom by inductor current freewheeling operation mode. Compared with boost PFC converter operating in continuous conduction mode (CCM) and discontinuous conduction mode (DCM), tri-state boost PFC converter extends the load range and is therefore more suitable for wide range of load variation. However, for universal input applications, the input power factor (PF) of the tri-state boost PFC converter is relatively low when the sinusoidal reference current control strategy is used. To improve the PF over the whole input voltage range, the input current and PF expressions of the tri-state boost PFC converter is derived and the non-sinusoidal reference current control strategy is proposed. A 400 W prototype of the tri-state boost PFC converter is built by using digital signal processing (DSP) as the controller. The experimental results verify the analysis results.
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Su, Zhanzhan, Zhengqiang Zhu, Yifu Zhang, Hua Zhang, and Qiankun Xiao. "Recrystallization Behavior of a Pure Cu Connection Interface with Ultrasonic Welding." Metals 11, no. 1 (2020): 61. http://dx.doi.org/10.3390/met11010061.
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Three-dimensional metal waveguide components are key components in the next generation of radio telescopes. Ultrasonic additive manufacturing technology combining ultrasonic welding and micro electrical discharge machining (micro-EDM) provides a new method for the overall manufacturing of waveguide elements, and the effective welding of Electrolytic Tough Pitch copper (Cu-ETP) sheets is the key process of this method. This study demonstrates that the orthogonal test optimization method is used to conduct ultrasonic welding tests on Cu-ETP. Specifically, electron backscattered diffraction (EBSD) technology is used to analyze the crystal grains, grain boundary types and texture changes during interface recrystallization. In addition, the finite element software ABAQUS 6.13 is employed to calculate the temperature field in order to determine the possibility of recrystallization of the welding interface. The results showed that the average grain size of the welding interface decreased from 20 to 1~2 μm. The Cu-ETP matrix is mainly composed of coarse grains with high-angle grain boundaries (HAGBs), while a large number of low-angle grain boundaries (LAGBs), subcrystals and fine equiaxed grains appear in the welded joint. At the same time, discontinuous dynamic recrystallization (DDRX) occurs in the less strained area, and continuous dynamic recrystallization (CDRX) is predominant in the greater strain area. The temperature field calculation shows that the peak temperature of the welding interface exceeds the recrystallization temperature of Cu-ETP from 379.05 to 433.2 °C.
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Mandrioli, Riccardo, Aleksandr Viatkin, Manel Hammami, Mattia Ricco, and Gabriele Grandi. "A Comprehensive AC Current Ripple Analysis and Performance Enhancement via Discontinuous PWM in Three-Phase Four-Leg Grid-Connected Inverters." Energies 13, no. 17 (2020): 4352. http://dx.doi.org/10.3390/en13174352.
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A complete analysis of the ac output current ripple in four-leg voltage source inverters considering multiple modulation schemes is provided. In detail, current ripple envelopes and peak-to-peak profiles have been determined in the whole fundamental period and a comprehensive method providing the current ripple rms has been achieved, all of them as a function of the modulation index. These characteristics have been determined for both phase and neutral currents, considering the most popular common-mode injection schemes. Particular attention has been paid to the performance of discontinuous pulse width modulation (DPWM) methods, including DPWMMAX and DPWMMIN, and their four most popular combinations DPWM0, DPWM1, DPWM2, and DPWM3. Furthermore, a comparison with a few continuous techniques (sinusoidal, centered pulse width modulations, and third harmonic injection) has been provided as well. Moreover, the average switching frequency and switching losses are analyzed, determining which PWM technique ensures minimum output current ripple within the linear modulation range at different assumptions. Numerical simulations and laboratory tests have been conducted to extensively verify all the analytical claims for all the considered PWM injections.
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Thommeret, N., J. S. Bailly, and C. Puech. "Robust extraction of thalwegs network from DTM: application on badlands." Hydrology and Earth System Sciences Discussions 7, no. 1 (2010): 879–905. http://dx.doi.org/10.5194/hessd-7-879-2010.
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Abstract. This paper presents methods to extract badlands thalwegs network from regular grid DTM by combining terrain morphology indices to a drainage algorithm. The computation of a continuous vector network will permit the study of the badlands spatial patterns. These methods aim at delineating a thalweg only where the DTM denotes a significant curvature with respect to DTM accuracy. It relies on three major steps. Firstly, discontinuous concave areas are detected from the DTM using morphological criteria; the plan curvature and the convergence index. Secondly, the concave areas are connected using a drainage algorithm which provides continuous and tree-structured thick scheme. We assume that these areas present physical significance and correspond to a gully floor area. Finally, the thick path is reduced to its main curve and vectorised to obtain a thalwegs network. The methods are applied on both virtual and actual cases DTM. The actual case is a LiDAR DTM of Draix Badlands (French Alps). The obtained networks are quantitatively compared both to the one obtained with usual drainage area criteria and to a reference network. The networks comparison shows the great potential of the convergence index based method for thalwegs network extraction.
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Rudenko, Yu V. "MODELING OF PROCESSES ON THE BASIS OF STATE SPACE AVERAGING IN BOOST CONVERTER WITH MAGNETICALLY COUPLED ELEMENTS." Praci Institutu elektrodinamiki Nacionalanoi akademii nauk Ukraini 2021, no. 58 (2021): 44–54. http://dx.doi.org/10.15407/publishing2021.58.044.
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The features of the state-space average method using Lagrange's theorems for calculation of processes in the boost converter with magnetically coupled elements (with autotransformer connection of inductors) in continuous currents mode are considered. A mathematical model of the converter based on relative variables has been developed, which makes it possible to calculate processes in a wide range of parameters taking into account the degree of magnetic coupling between inductive elements, including the definition of constant and pulsating components. It is shown that to obtain a complete system of the algebraic equations as a mathematical model of converters, which provides its single solution, it is advisable to additionally use the ratio according to energy balance in reactive elements in a steady state at the operation intervals of the converter during commutation period. The boundary dependences of boost converter parameters with magnetically coupled elements between the modes of discontinuous and continuous currents are calculated. The relative characteristics of the converter have been studied, which demonstrate the influence of imperfection of the magnetic coupling in the regulation zone of the relative duration value of switching interval. Ref. 21, fig. 6.
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Baklouti, A., N. Elaloui, and I. Kedim. "The Selberg–Weil–Kobayashi rigidity theorem: The rank one solvable case." International Journal of Mathematics 27, no. 10 (2016): 1650085. http://dx.doi.org/10.1142/s0129167x16500853.
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A local rigidity theorem was proved by Selberg and Weil for Riemannian symmetric spaces and generalized by Kobayashi for a non-Riemannian homogeneous space [Formula: see text], determining explicitly which homogeneous spaces [Formula: see text] allow nontrivial continuous deformations of co-compact discontinuous groups. When [Formula: see text] is assumed to be exponential solvable and [Formula: see text] is a maximal subgroup, an analog of such a theorem states that the local rigidity holds if and only if [Formula: see text] is isomorphic to the group Aff([Formula: see text]) of affine transformations of the real line (cf. [L. Abdelmoula, A. Baklouti and I. Kédim, The Selberg–Weil–Kobayashi rigidity theorem for exponential Lie groups, Int. Math. Res. Not. 17 (2012) 4062–4084.]). The present paper deals with the more general context, when [Formula: see text] is a connected solvable Lie group and [Formula: see text] a maximal nonnormal subgroup of [Formula: see text]. We prove that any discontinuous group [Formula: see text] for a homogeneous space [Formula: see text] is abelian and at most of rank 2. Then we discuss an analog of the Selberg–Weil–Kobayashi local rigidity theorem in this solvable setting. In contrast to the semi-simple setting, the [Formula: see text]-action on [Formula: see text] is not always effective, and thus the space of group theoretic deformations (formal deformations) [Formula: see text] could be larger than geometric deformation spaces. We determine [Formula: see text] and also its quotient modulo uneffective parts when the rank [Formula: see text]. Unlike the context of exponential solvable case, we prove the existence of formal colored discontinuous groups. That is, the parameter space admits a mixture of locally rigid and formally nonrigid deformations.
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Kawiecka, R., A. Krawczyk, P. Lewińska, et al. "Mining Activity and its Remains - The Possibilities of Obtaining, Analysing and Disseminating of Various Data on the Example of Miedzianka, Lower Silesia, Poland." Journal of Applied Engineering Sciences 8, no. 2 (2018): 65–72. http://dx.doi.org/10.2478/jaes-2018-0020.
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Abstract The article presents comprehensive documentation of the situation of post-mining Miedzianka village (former town), which is located in Lower Silesia, in south-western Poland. Due to the long-term expansive mining exploitation since the 14th century, over time Miedzianka was completely destroyed and depopulated, thus nowadays, only a few inhabitants live there. The basis for the conducted research area were changes in land and urban structure that have been occurring for centuries in connection with mining operation of copper and uranium. The authors focused on presenting the changes using archival cartographic documentation, land surveying measurements and 3D modelling. That data allowed to determine on the ground specific sites related to mining operations, discover old urban buildings, performing their 3D models and finding places potentially threatened by continuous and discontinuous deformations. The combination of all the data allowed to present the full situation that occurred in Miedzianka.
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Thommeret, N., J. S. Bailly, and C. Puech. "Extraction of thalweg networks from DTMs: application to badlands." Hydrology and Earth System Sciences 14, no. 8 (2010): 1527–36. http://dx.doi.org/10.5194/hess-14-1527-2010.
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Abstract. To study gully spatial patterns in the badlands using a continuous thalweg vector network, this paper presents methods to extract the badlands' thalweg network from a regular grid digital terrain model (DTM) by combining terrain morphology indices with a drainage algorithm. This method will delineate a thalweg only where the DTM denotes a significant curvature with respect to DTM accuracy and relies on three major steps. First, discontinuous concave areas were detected from the DTM using morphological criteria, either the plan curvature or the convergence index. Second, the concave areas were connected using a drainage algorithm, which provides a continuous, thick, tree-structured scheme. We assumed that these areas were physically significant and corresponded to a gully floor. Finally, the thick path was reduced to its main course and vectorised to obtain a thalweg network. The methods were applied to both virtual and actual DTM cases. The actual case was a LiDAR DTM of the Draix badlands in the French Alps. The obtained networks were quantitatively compared, both with a network obtained using the usual drainage area criteria and with a reference network mapped in the field. The CI-based network showed the great potential for thalweg network extraction.
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Al-Asbahi, Khaled Mohammed Moqbel. "Insights into the Semantics of Reduplication in English and Arabic." International Journal of English Linguistics 10, no. 1 (2020): 384. http://dx.doi.org/10.5539/ijel.v10n1p384.
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The paper aims to describe and compare the semantics of reduplication in English and Arabic. The paper shows more semantic similarities in reduplication than differences between both languages; although, Arabic reduplication is noted to be semantically more productive than English reduplication. Both languages divide reduplication into full/partial, free/bound, and continuous/discontinuous. Moreover, both languages share the senses of reduplication like; repetition, emphasis, intensity, onomatopoeia, contempt, affection, plurality, non-uniformity, and instability, nonsense, spread out, scatter, movement, contrast, continuity, completion, and lack of control. The semantic connection was developed between most of these concepts, which showed that ambiguity was common between both languages. Both the languages used reduplication in the nursery rhymes, lyrics, games, prayers, second language teaching, children’s phonics cartoons, advertisements, tongue twisters, slogans, newspaper headlines, and political and ideological rhetoric. These similarities support the belief of some linguists stating that different languages in the world share a variety of ‘universal’ semantic features. The study concluded that Arabic reduplication was semantically more productive than English reduplication.
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Itoh, Makoto, and Leon O. Chua. "Parasitic Effects on Memristor Dynamics." International Journal of Bifurcation and Chaos 26, no. 06 (2016): 1630014. http://dx.doi.org/10.1142/s0218127416300147.
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In this paper, we show that parasitic elements have a significant effect on the dynamics of memristor circuits. We first show that certain [Formula: see text]-terminal elements such as memristors, memcapacitors, and meminductors can be used as nonvolatile memories, if the principle of conservation of state variables hold by open-circuiting, or short-circuiting, their terminals. We also show that a passive memristor with a strictly-increasing constitutive relation will eventually lose its stored flux when we switch off the power if there is a parasitic capacitance across the memristor. Similarly, a memcapacitor (resp., meminductor) with a positive memcapacitance (resp., meminductance) will eventually lose their stored physical states when we switch off the power, if it is connected to a parasitic resistance. We then show that the discontinuous jump that circuit engineers assumed to occur at impasse points of memristor circuits contradicts the principles of conservation of charge and flux at the time of the discontinuous jump. A parasitic element can be used to break an impasse point, resulting in the emergence of a continuous oscillation in the circuit. We also define a distance, a diameter, and a dimension, for each circuit element in order to measure the complexity order of the parasitic elements. They can be used to find higher-order parasitic elements which can break impasse points. Furthermore, we derived a memristor-based Chua’s circuit from a three-element circuit containing a memristor by connecting two parasitic memcapacitances to break the impasse points. We finally show that a higher-order parasitic element can be used for breaking the impasse points on two-dimensional and three-dimensional constrained spaces.
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Ando, Kei, Kazuyoshi Kobayashi, Masaaki Machino, et al. "Connection of discontinuous segments in early functional recovery from thoracic ossification of the posterior longitudinal ligament treated with posterior instrumented surgery." Journal of Neurosurgery: Spine 32, no. 2 (2020): 200–206. http://dx.doi.org/10.3171/2019.8.spine19604.
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OBJECTIVEThe objective of this study was to investigate the relationship between morphological changes in thoracic ossification of the posterior longitudinal ligament (T-OPLL) and postoperative neurological recovery after thoracic posterior fusion surgery. Changes of OPLL morphology and postoperative recovery in cases with T-OPLL have not been examined.METHODSIn this prospective study, the authors evaluated data from 44 patients (23 male and 21 female) who underwent posterior decompression and fusion surgery with instrumentation for the treatment of T-OPLL at our hospital. The patients’ mean age at surgery was 50.7 years (range 38–68 years). The minimum duration of follow-up was 2 years. The location of thoracic ossification of the ligamentum flavum (T-OLF), T-OLF at the OPLL level, OPLL morphology, fusion range, estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA recovery rate were investigated. Reconstructed sagittal multislice CT images were obtained before and at 3 and 6 months and 1 and 2 years after surgery. The basic fusion area was 3 vertebrae above and below the OPLL lesion. All parameters were compared between patients with and without continuity across the disc space at the OPLL at 3 and 6 months after surgery.RESULTSThe preoperative morphology of OPLL was discontinuous across the disc space between the rostral and caudal ossification regions on sagittal CT images in all but one of the patients. Postoperatively, these segments became continuous in 42 patients (97.7%; occurring by 6.6 months on average) without progression of OPLL thickness. Patients with continuity at 3 months had significantly lower rates of diabetes mellitus (p < 0.05) and motor palsy in the lower extremities (p < 0.01). The group with continuity also had significantly higher mean postoperative JOA scores at 3 (p < 0.01) and 6 (p < 0.05) months and mean JOA recovery rates at 3 and 6 months (both p < 0.01) after surgery.CONCLUSIONSPreoperatively, discontinuity of rostral and caudal ossified lesions was found on CT in all patients but one of this group of 44 patients who needed surgery for T-OPLL. Rigid fixation with instrumentation may have allowed these segments to connect at the OPLL. Such OPLL continuity at an early stage after surgery may accelerate spinal cord recovery.
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Roth, Jenny, Michaela Huber, Annkatrin Juenger, and James H. Liu. "It’s about valence: Historical continuity or historical discontinuity as a threat to social identity." Journal of Social and Political Psychology 5, no. 2 (2017): 320–41. http://dx.doi.org/10.5964/jspp.v5i2.677.
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National identity is underpinned by historical representations. Recent research shows that narratives presenting an in-group’s history as discontinuous rather than continuous raise collective angst, suggesting that historical discontinuity threatens social identity. This previous research has focused on positive aspects of an in-group’s past. The present research aims to extend the findings to go beyond positive histories. We suggest that when the in-group’s actions in the past are presented as negative, historical continuity instead of discontinuity will increase perceived identity threat because a negative, continuous history threatens group members’ need for a positive social identity in the present. In an experiment with a sample size of N = 316, we manipulated the narrated valence of in-group actions during the historical event of the approval of the German constitutional law by framing the group’s actions in either positive or negative terms. In addition, we presented the in-group’s history as connected or disconnected to the in-group’s present. Results demonstrate that historical continuity only decreased identity threat compared to historical discontinuity when the in-group’s past behavior was presented as positive. When the in-group’s past was presented as negative, continuity even increased identity threat compared to historical discontinuity. These results were particularly pronounced for people who strongly identified with their national in-group. We discuss implications of the findings for political communication and managing a nation’s perception of social identity threat.
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COOMBES, S., Y. M. LAI, M. ŞAYLI, and R. THUL. "Networks of piecewise linear neural mass models." European Journal of Applied Mathematics 29, no. 5 (2018): 869–90. http://dx.doi.org/10.1017/s0956792518000050.
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Neural mass models are ubiquitous in large-scale brain modelling. At the node level, they are written in terms of a set of ordinary differential equations with a non-linearity that is typically a sigmoidal shape. Using structural data from brain atlases, they may be connected into a network to investigate the emergence of functional dynamic states, such as synchrony. With the simple restriction of the classic sigmoidal non-linearity to a piecewise linear caricature, we show that the famous Wilson–Cowan neural mass model can be explicitly analysed at both the node and network level. The construction of periodic orbits at the node level is achieved by patching together matrix exponential solutions, and stability is determined using Floquet theory. For networks with interactions described by circulant matrices, we show that the stability of the synchronous state can be determined in terms of a low-dimensional Floquet problem parameterised by the eigenvalues of the interaction matrix. Moreover, this network Floquet problem is readily solved using linear algebra to predict the onset of spatio-temporal network patterns arising from a synchronous instability. We further consider the case of a discontinuous choice for the node non-linearity, namely the replacement of the sigmoid by a Heaviside non-linearity. This gives rise to a continuous-time switching network. At the node level, this allows for the existence of unstable sliding periodic orbits, which we explicitly construct. The stability of a periodic orbit is now treated with a modification of Floquet theory to treat the evolution of small perturbations through switching manifolds via the use of saltation matrices. At the network level, the stability analysis of the synchronous state is considerably more challenging. Here, we report on the use of ideas originally developed for the study of Glass networks to treat the stability of periodic network states in neural mass models with discontinuous interactions.
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Sommer, J. R., T. High, P. Ingram, D. Kopf, R. Nassar, and I. Taylor. "Avian Extended Junctional SR: 3-D Geometry Rendered in Stereo." Microscopy and Microanalysis 3, S2 (1997): 247–48. http://dx.doi.org/10.1017/s1431927600008126.
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Extended junctional sarcoplasmic reticulum (EJSR) is an invariant differentiation of the sarcoplasmic reticulum (SR) in bird cardiac myocytes (CM) and central to excitation-contraction coupling (ECC). EJSR occurs as both continuous and discontinuous extensions of junctional sarcoplasmic reticulum (JSR), and surrounds and pervades the Z/I band as the “ EJSR Z-rete” whose geometry has mechanistic implications for the function of “couplings” in ECC, in general. “Peripheral coupling(s)” (PC) in birds, and the additional “interior coupling(s)” (IC) at transverse tubules (TT) in mammals, are formed by tight apposition to plasmalemma of JSR, a specialized calcium (Ca) store of the SR. Free SR (FSR; i.e. free of JSR/EJSR specializations) is the rest of the smooth, tubular SR network, which connects intercalated patches of EJSR forming the EJSR Z-retes and, elsewhere, displays both longitudinal and transverse geometries in surrounding the contractile material for the purpose of sequestering Ca after each muscle contraction. Except for EJSR having no plasmalemmal contact, morphologically, EJSR and JSR are homologues:1 both have similar sizes; are studded (approx. 32 nm center-to-center) with junctional processes (JP; ryanodine receptor (RyR)/-Ca-release channels);
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Kadouri, Youssef, Damien Carnicelli, Hachem El Sayegh, Lounis Benslimane, and Yassine Nouini. "Pathogenesis, Diagnosis, and Management of Splenogonadal Fusion: A Literature Review." Case Reports in Urology 2020 (October 8, 2020): 1–7. http://dx.doi.org/10.1155/2020/8876219.
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Introduction. Splenogonadal fusion is a rare congenital anomaly, defined by the presence of ectopic splenic tissue caused by an abnormal connection between the spleen and the gonad or mesonephrotic derivatives during the embryonic period. Materials and Methods. By reporting an observational case and performing a review of the literature according to the CARE guidelines (using the PubMed database and guidelines from urology, general surgery, and pediatric learned societies), we present the embryological genesis of the splenogonadal fusion, the associated anatomical anomalies, and the diagnostic procedure. Observation. We report the case of a patient aged 45, with no notable history, reporting left testicular pain. A small nodule on the upper pole of the left testicular was clinically palpable. Tumor markers were normal, and scrotal ultrasound depicted a hypoechoic hypervascular nodule measuring 8∗6∗8 mm. After validation in a multidisciplinary oncology consultation meeting and opinion from a uro-andrologist expert, the patient underwent an inguinal lumpectomy with an extemporaneous examination which did not objectify any signs of malignancy. Ultimately, it is a normal spleen tissue in the testicular ectopic position. Discussion. Splenogonadal fusion corresponds to a rare congenital malformation; less than 200 cases have been published in the literature, most often affecting boys, with a sex ratio of 15/1. Two types are described, depending on the continuity of the link between the orthotopic spleen and the gonad: the continuous and discontinuous forms. In a third of the cases, there are associated congenital malformations and particularly in the continuous forms (44 to 50% of the cases): anomalies of the limbs, micrognathia, microgyria, and hepatic and digestive abnormalities. Cryptorchidism is associated with the continuous form in 31% of cases. The preoperative diagnosis remains difficult because of its morphological and clinical characteristics suggesting a tumor process.
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Delatorre, M., TS Vasconcelos, NL Cunha, et al. "Implementing new northernmost records to modelling the distribution of Hypsiboas caingua (Anura: Hylidae) in South America." Brazilian Journal of Biology 74, no. 4 (2014): 854–60. http://dx.doi.org/10.1590/1519-6984.05113.
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New northwestern records of the striped treefrog Hypsiboas caingua (Carrizo, 1991 “1990”) are presented for Brazil, extending its known geographic distribution approximately 115 km northward (linear distance) of the previous northernmost record of the species. In all new localities, individuals of H. caingua were only found in calling activity under temperatures below 18°C. The species appears to be associated with Atlantic Forest, although it had already been recorded in Cerrado. Although the scientific literature data suggests that H. caingua presents discontinuous geographical distribution, three methods of distribution modelling based on climatic data show that the species' distribution is continuous. The gap in the distribution may be related to the lack of field surveys in the regions that connect these populations, especially in colder periods. Nevertheless, factors other than climate might also be responsible for the current distribution of H. caingua, since the species was absent in well-surveyed sites situated between the areas of modeled distribution. Therefore, further studies on natural history, populations' genetic structure, and geographic distribution models implementing factors other than climate will be important to elucidate some ecological and evolutionary aspects of the distribution of H. caingua in South America.
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SHIN, JEONG WOO, and YOUNG-SHIN LEE. "DYNAMIC CRACK PROPAGATION IN A FUNCTIONALLY GRADED PIEZOELECTRIC INTERFACE LAYER BETWEEN TWO DISSIMILAR PIEZOELECTRIC LAYERS UNDER ELECTROMECHANICAL LOADING." International Journal of Modern Physics: Conference Series 06 (January 2012): 55–60. http://dx.doi.org/10.1142/s2010194512002930.
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The dynamic propagation of a crack in a functionally graded piezoelectric material (FGPM) interface layer between two dissimilar piezoelectric layers under anti-plane shear is analyzed using the integral transform approaches. The properties of the FGPM layers vary continuously along the thickness. FGPM layer and the two homogeneous piezoelectric layers are connected weak-discontinuously. A constant velocity Yoffe-type moving crack is considered. Numerical values on the dynamic energy release rate (DERR) are presented for the FGPM. Followings are helpful to increase of the resistance of the crack propagation of the FGPM interface layer: (a) certain direction and magnitude of the electric loading; (b) increase of the thickness of the FGPM interface layer; (c) increase of the thickness of the homogeneous piezoelectric layer which has larger material properties than those of the crack plane in the FGPM interface layer. The DERR always increases with the increase of crack moving velocity and the gradient of the material properties.
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Green, Joseph, Daniel Ryckman, and Michael Cromer. "A Continuum Model for Complex Flows of Shear Thickening Colloidal Solutions." Fluids 4, no. 1 (2019): 21. http://dx.doi.org/10.3390/fluids4010021.
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Colloidal shear thickening fluids (STFs) have applications ranging from commercial use to those of interest to the army and law enforcement, and the oil industry. The theoretical understanding of the flow of these particulate suspensions has predominantly been focused through detailed particle simulations. While these simulations are able to accurately capture and predict the behavior of suspensions in simple flows, they are not tractable for more complex flows such as those occurring in applications. The model presented in this work, a modification of an earlier constitutive model by Stickel et al. J. Rheol. 2006, 50, 379–413, describes the evolution of a structure tensor, which is related to the particle mean free-path length. The model contains few adjustable parameters, includes nonlinear terms in the structure, and is able to predict the full range of rheological behavior including shear and extensional thickening (continuous and discontinuous). In order to demonstrate its capability for complex flow simulations, we compare the results of simulations of the model in a simple one-dimensional channel flow versus a full two-dimensional simulation. Ultimately, the model presented is a continuum model shown to predict shear and extensional thickening, as observed in experiment, with a connection to the physical microstructure, and has the capability of helping understand the behavior of STFs in complex flows.
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Brennand, T. A., and D. R. Sharpe. "Ice-sheet dynamics and subglacial meltwater regime inferred from form and sedimentology of glaciofluvial systems: Victoria Island, District of Franklin, Northwest Territories." Canadian Journal of Earth Sciences 30, no. 5 (1993): 928–44. http://dx.doi.org/10.1139/e93-078.
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On Victoria Island, tunnel channels, eskers, and associated fans and extended deposits together constitute channelized glaciofluvial systems. Flutes and drumlinoid ridges, interpreted as residuals left by erosive, catastrophic, subglacial meltwater sheet flows, lie adjacent to these systems. One tunnel channel is described in detail. It exhibits deep scours, a discontinuous thalweg, sculpted margins, and flutes on the downflow side of one wall, features indicative of complex flow and possibly several flow events. The tunnel channel is interpreted as the product of erosion by catastrophic, subglacial meltwater flow in a combined ice – substrate (R/N) channel.Esker sediments and morphology are used to infer details of the depositional environment and meltwater regime. A continuous esker with fans and extended deposits records seasonally controlled discharge events through an R-channel. These features may also suggest a grounding-line environment, thin ice, and localized ice floatation events. Less well connected ridges also record seasonally controlled meltwater rhythms and were produced within a thinning and stagnating ice mass; the depositional environment may have been in a subglacial R-channel or an ice-walled reentrant.Differences in the drainage system associated with each glaciofluvial landform, and temporal disconnection between tunnel channel and esker formation, is also suggested by possible paleoflow reversals between inferred catastrophic and seasonally controlled drainage phases. Changes in ice-sheet profiles between events may have been responsible.
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Köhler, Peter, Christoph Nehrbass-Ahles, Jochen Schmitt, Thomas F. Stocker, and Hubertus Fischer. "A 156 kyr smoothed history of the atmospheric greenhouse gases CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O and their radiative forcing." Earth System Science Data 9, no. 1 (2017): 363–87. http://dx.doi.org/10.5194/essd-9-363-2017.
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Abstract. Continuous records of the atmospheric greenhouse gases (GHGs) CO2, CH4, and N2O are necessary input data for transient climate simulations, and their associated radiative forcing represents important components in analyses of climate sensitivity and feedbacks. Since the available data from ice cores are discontinuous and partly ambiguous, a well-documented decision process during data compilation followed by some interpolating post-processing is necessary to obtain those desired time series. Here, we document our best possible data compilation of published ice core records and recent measurements on firn air and atmospheric samples spanning the interval from the penultimate glacial maximum ( ∼ 156 kyr BP) to the beginning of the year 2016 CE. We use the most recent age scales for the ice core data and apply a smoothing spline method to translate the discrete and irregularly spaced data points into continuous time series. These splines are then used to compute the radiative forcing for each GHG using well-established, simple formulations. We compile only a Southern Hemisphere record of CH4 and discuss how much larger a Northern Hemisphere or global CH4 record might have been due to its interpolar difference. The uncertainties of the individual data points are considered in the spline procedure. Based on the given data resolution, time-dependent cutoff periods of the spline, defining the degree of smoothing, are prescribed, ranging from 5000 years for the less resolved older parts of the records to 4 years for the densely sampled recent years. The computed splines seamlessly describe the GHG evolution on orbital and millennial timescales for glacial and glacial–interglacial variations and on centennial and decadal timescales for anthropogenic times. Data connected with this paper, including raw data and final splines, are available at doi:10.1594/PANGAEA.871273.
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Cai, Qing, Mahardhika Pratama, and Sameer Alam. "Interdependency and Vulnerability of Multipartite Networks under Target Node Attacks." Complexity 2019 (November 20, 2019): 1–16. http://dx.doi.org/10.1155/2019/2680972.
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Complex networks in reality may suffer from target attacks which can trigger the breakdown of the entire network. It is therefore pivotal to evaluate the extent to which a network could withstand perturbations. The research on network robustness has proven as a potent instrument towards that purpose. The last two decades have witnessed the enthusiasm on the studies of network robustness. However, existing studies on network robustness mainly focus on multilayer networks while little attention is paid to multipartite networks which are an indispensable part of complex networks. In this study, we investigate the robustness of multipartite networks under intentional node attacks. We develop two network models based on the largest connected component theory to depict the cascading failures on multipartite networks under target attacks. We then investigate the robustness of computer-generated multipartite networks with respect to eight node centrality metrics. We discover that the robustness of multipartite networks could display either discontinuous or continuous phase transitions. Interestingly, we discover that larger number of partite sets of a multipartite network could increase its robustness which is opposite to the phenomenon observed on multilayer networks. Our findings shed new lights on the robust structure design of complex systems. We finally present useful discussions on the applications of existing percolation theories that are well studied for network robustness analysis to multipartite networks. We show that existing percolation theories are not amenable to multipartite networks. Percolation on multipartite networks still deserves in-depth efforts.
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Liu, H. C., G. J. He, X. M. Zhang, W. Jiang, and S. G. Ling. "Spatiotemporal Mining of Time-Series Remote Sensing Images Based on Sequential Pattern Mining." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences II-4/W2 (July 10, 2015): 111–18. http://dx.doi.org/10.5194/isprsannals-ii-4-w2-111-2015.
Full textAbstract:
With the continuous development of satellite techniques, it is now possible to acquire a regular series of images concerning a given geographical zone with both high accuracy and low cost. Research on how best to effectively process huge volumes of observational data obtained on different dates for a specific geographical zone, and to exploit the valuable information regarding land cover contained in these images has received increasing interest from the remote sensing community. In contrast to traditional land cover change measures using pair-wise comparisons that emphasize the compositional or configurational changes between dates, this research focuses on the analysis of the temporal sequence of land cover dynamics, which refers to the succession of land cover types for a given area over more than two observational periods. Using a time series of classified Landsat images, ranging from 2006 to 2011, a sequential pattern mining method was extended to this spatiotemporal context to extract sets of connected pixels sharing similar temporal evolutions. The resultant sequential patterns could be selected (or not) based on the range of support values. These selected patterns were used to explore the spatial compositions and temporal evolutions of land cover change within the study region. Experimental results showed that continuous patterns that represent consistent land cover over time appeared as quite homogeneous zones, which agreed with our domain knowledge. Discontinuous patterns that represent land cover change trajectories were dominated by the transition from vegetation to bare land, especially during 2009–2010. This approach quantified land cover changes in terms of the percentage area affected and mapped the spatial distribution of these changes. Sequential pattern mining has been used for string mining or itemset mining in transactions analysis. The expected novel significance of this study is the generalization of the application of the sequential pattern mining method for capturing the spatial variability of landscape patterns, and their trajectories of change, to reveal information regarding process regularities with satellite imagery.
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Park, Hyun Jin, Kyu-Lim Lee, Young-Chun Gil, Ji-Hyun Lee, Kyung-Seok Hu, and Hee-Jin Kim. "Sonographic Analysis of the Upper Labial Orbicularis Oris and Its Clinical Implications." Aesthetic Surgery Journal 40, no. 7 (2019): 778–83. http://dx.doi.org/10.1093/asj/sjz341.
Full textAbstract:
Abstract Background Purse string lips, which include the vertical wrinkles over the lips, are frequently observed in aged individuals. Botulinum toxin and fillers are routinely injected into these areas to remove the wrinkles; however, the anatomy of the orbicularis oris muscle (OOr) near the vermilion border area has not been well defined. Objectives The aim of this study was therefore to identify any morphological differences of the upper OOr via sonographic imaging. Methods The upper lip muscles as observed utilizing an ultrasound device were divided into 2 muscles (pars peripheralis and pars marginalis) that were subsequently divided into a further 2 types (Type I and Type II) associated with the development of the pars marginalis. Type II was further divided into Type IIa and Type IIb depending on whether the muscle fibers were well developed and connected. Results On the midline of the lip, Type I, in which the pars marginalis was rarely observed and only appeared in traces, was observed in 20.0% of the volunteers. Type IIa, in which the pars marginalis was well-developed and appeared continuous, was observed in 42.9% of the volunteers. Type IIb, in which the pars marginalis was observed but appeared discontinuous, was observed in 37.1% of the volunteers. Conclusions The shapes of the upper pars marginalis of the OOr varied markedly between volunteers. Type classification of the OOr based on its shape and the lip appearance serves as a reliable source of reference information to be utilized when injecting botulinum toxin into the upper lip.