Articoli di riviste: "Continuous arcs"

1

Nikiel, Jacek. "Continuous images of arcs". Proceedings of the American Mathematical Society 103, n. 3 (1 marzo 1988): 961. http://dx.doi.org/10.1090/s0002-9939-1988-0947691-9.

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Uahabi, Kaoutar Lamrini, e Mohammed Zaoui. "Behavior of the Trinomial ArcsB(n,k,r)when0<α<1". International Journal of Mathematics and Mathematical Sciences 2007 (2007): 1–8. http://dx.doi.org/10.1155/2007/91535.

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We deal with the familyB(n,k,r)of trinomial arcs defined as the set of roots of the trinomial equationzn=αzk+(1−α), wherez=ρeiθis a complex number,nandkare two integers such that0<k<n, andαis a real number between0and1. These arcsB(n,k,r)are continuous arcs inside the unit disk, expressed in polar coordinates(ρ,θ). The question is to prove thatρ(θ)is a decreasing function, for each trinomial arcB(n,k,r).

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Fichou, Goulwen, e Masahiro Shiota. "Continuous mappings between spaces of arcs". Bulletin de la Société mathématique de France 143, n. 2 (2015): 315–37. http://dx.doi.org/10.24033/bsmf.2689.

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Bankston, Paul. "On continuous images of ultra-arcs". Topology and its Applications 261 (luglio 2019): 7–21. http://dx.doi.org/10.1016/j.topol.2019.05.001.

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Nikiel, J., L. B. Treybig e H. M. Tuncali. "Local connectivity and maps onto non-metrizable arcs". International Journal of Mathematics and Mathematical Sciences 20, n. 4 (1997): 681–88. http://dx.doi.org/10.1155/s0161171297000938.

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Three classes of locally connected continua which admit sufficiently many maps onto non-metric arcs are investigated. It is proved that all continua in those classes are continuous images of arcs and, therefore, have other quite nice properties.

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Daniel, D., J. Nikiel, L. B. Treybig, M. Tuncali e E. D. Tymchatyn. "Continuous images of arcs: Extensions of Cornette's Theorem". Topology and its Applications 195 (novembre 2015): 63–69. http://dx.doi.org/10.1016/j.topol.2015.09.030.

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Nikiel, J., H. M. Tuncali e E. D. Tymchatyn. "Continuous images of arcs and inverse limit methods". Memoirs of the American Mathematical Society 104, n. 498 (1993): 0. http://dx.doi.org/10.1090/memo/0498.

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8

Lončar, Ivan. "ℵ1-directed inverse systems of continuous images of arcs". International Journal of Mathematics and Mathematical Sciences 24, n. 2 (2000): 109–19. http://dx.doi.org/10.1155/s016117120000363x.

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The main purpose of this paper is to prove that ifX={Xa,pab,A}is a usualℵ1-directed inverse system of continuous images of arcs with monotone bonding mappings, thenX=limXis a continuous image of an arc (Theorem 2.4). Some applications of this statement are also given.

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9

Janson, Svante. "Random coverings of the circle by arcs with restricted endpoints". Journal of Applied Probability 25, n. 1 (marzo 1988): 215–19. http://dx.doi.org/10.2307/3214248.

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A circle is covered by random arcs with a given length a and endpoints chosen (independently and uniformly) among m equispaced points on the circle. The asymptotic distribution as a → 0 and m → ∞of the number of arcs required for complete coverage is given. The result connects earlier results for the cases ma = 1 (a discrete problem) and m = ∞ (the continuous limiting case).

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Janson, Svante. "Random coverings of the circle by arcs with restricted endpoints". Journal of Applied Probability 25, n. 01 (marzo 1988): 215–19. http://dx.doi.org/10.1017/s002190020004078x.

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A circle is covered by random arcs with a given length a and endpoints chosen (independently and uniformly) among m equispaced points on the circle. The asymptotic distribution as a → 0 and m → ∞of the number of arcs required for complete coverage is given. The result connects earlier results for the cases ma = 1 (a discrete problem) and m = ∞ (the continuous limiting case).

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11

Loncar, I. "A note on inverse limits of continuous images of arcs". Publicacions Matemàtiques 43 (1 luglio 1999): 485–99. http://dx.doi.org/10.5565/publmat_43299_03.

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Prajs, Janusz R. "A continuous circle of pseudo-arcs filling up the annulus". Transactions of the American Mathematical Society 352, n. 4 (1 luglio 1999): 1743–57. http://dx.doi.org/10.1090/s0002-9947-99-02330-2.

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Prajs, Janusz R. "A continuous decomposition of the Menger curve into pseudo-arcs". Proceedings of the American Mathematical Society 128, n. 8 (25 febbraio 2000): 2487–91. http://dx.doi.org/10.1090/s0002-9939-00-05615-x.

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14

Cumnock, J. A., L. G. Blomberg, A. Kullen e T. Karlsson. "Small-scale characteristics of extremely high latitude aurora". Annales Geophysicae 27, n. 9 (1 settembre 2009): 3335–47. http://dx.doi.org/10.5194/angeo-27-3335-2009.

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Abstract. We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF By. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.

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Gauthier, P. M., e E. S. Zeron. "Approximation On Arcs and Dendrites Going to Infinity in ℂn". Canadian Mathematical Bulletin 45, n. 1 (1 marzo 2002): 80–85. http://dx.doi.org/10.4153/cmb-2002-008-1.

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Hamzezadeh, F., e H. Salehi Fathabadi. "Capacity Expansion and Reliability Evaluation on the Networks Flows with Continuous Stochastic Functional Capacity". Journal of Applied Mathematics 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/876260.

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In many systems such as computer network, fuel distribution, and transportation system, it is necessary to change the capacity of some arcs in order to increase maximum flow value from sourcesto sinkt, while the capacity change incurs minimum cost. In real-time networks, some factors cause loss of arc’s flow. For example, in some flow distribution systems, evaporation, erosion or sediment in pipes waste the flow. Here we define a real capacity, or the so-calledfunctional capacity,which is the operational capacity of an arc. In other words, the functional capacity of an arc equals the possible maximum flow that may pass through the arc. Increasing the functional arcs capacities incurs some cost. There is a certain resource available to cover the costs. First, we construct a mathematical model to minimize the total cost of expanding the functional capacities to the required levels. Then, we consider the loss of flow on each arc as a stochastic variable and compute the system reliability.

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Krampit, N. Yu, e A. G. Krampit. "Mechanical properties of welded joints in welding with continuous and pulsed arcs". Welding International 25, n. 8 (agosto 2011): 626–28. http://dx.doi.org/10.1080/09507116.2011.566734.

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18

Boroński, Jan P., e Michel Smith. "Continuous curves of nonmetric pseudo-arcs and semi-conjugacies to interval maps". Topology and its Applications 282 (agosto 2020): 107309. http://dx.doi.org/10.1016/j.topol.2020.107309.

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19

Ferguson, Dale C., Phil Perillat e Boris Vayner. "Spectral Characteristics of GEO Satellite Arcing – 300 To 350 MHz". Journal of the Astronautical Sciences 69, n. 1 (25 gennaio 2022): 139–48. http://dx.doi.org/10.1007/s40295-021-00295-8.

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AbstractIn a series of previous papers, the detection of arcing on GPS, Van Allen Probe, and GEO satellites with the Arecibo Observatory Wm. E. Gordon 305 m radiotelescope has been reported and elaborated. In this paper, characteristics of the radiofrequency spectra of two true GEO satellites are reported as they were measured with the Arecibo Mock spectrometer every 9.6 microseconds, and are contrasted with spectra of impulsive RFI (RadioFrequency Interference) events. It is shown that the arc spectra in the 300–350 MHz range are not continuous, but consist of a number of narrow spectral lines. These lines are consistent within the duration of single arcs, but change between arcs, so that when averaged over many arcs, the appearance of a continuous spectrum is approximated. This behavior is replicated in the laboratory within charging-induced vacuum arcing on small solar array samples. In contrast, the spectrum of impulsive RFI (including, but not limited to lightning strokes) is essentially random from one 9.6 microsecond sampling interval to the next. Since the spectrum of a true arc changes little throughout many samples, it cannot be due to the risetime of the arc current, which is much less than one sampling interval. Furthermore, in laboratory experiments done at very high time resolution (< 1 ns), there is little correlation between the arc current spectra and the arcing RFI spectra, indicating that even arc current fluctuations within each arc can have little to do with the UHF spectra observed.

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20

Ricci, N., e F. Verni. "Motor and predatory behavior of Litonotus lamella (Protozoa, Ciliata)". Canadian Journal of Zoology 66, n. 9 (1 settembre 1988): 1973–81. http://dx.doi.org/10.1139/z88-289.

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The ethogram of Litonotus lamella is described and discussed. Individuals of the species creep on the substrate at a velocity of 189 ± 40 μm/s, moving toward the right along geometrically perfect arcs with different radii, lengths, and amplitudes. The arcs are connected by four types of reaction: the continuous trajectory change, the smooth trajectory change, the rough trajectory change, and the side-stepping reaction. Litonotus lamella swims along a helicoid, keeping its ciliated surface outwards. Under appropriate conditions, L. lamella kills, engulfs, and eats the ciliate Euplotes crassus. This predatory behavior consists of two different sets of behavioral patterns; the first is part of the normal motor behavior, while the second comprises behavioral patterns performed characteristically and exclusively during the predatory activity.

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MATOUŠEK, JIŘÍ. "Near-Optimal Separators in String Graphs". Combinatorics, Probability and Computing 23, n. 1 (7 ottobre 2013): 135–39. http://dx.doi.org/10.1017/s0963548313000400.

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Let G be a string graph (an intersection graph of continuous arcs in the plane) with m edges. Fox and Pach proved that G has a separator consisting of $O(m^{3/4}\sqrt{\log m})$ vertices, and they conjectured that the bound of $O(\sqrt m)$ actually holds. We obtain separators with $O(\sqrt m \,\log m)$ vertices.

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Berckmoes, Lidewyde H., Marie Rosenkrantz Lindegaard e Dennis Rodgers. "Introduction". Conflict and Society 7, n. 1 (1 giugno 2021): 96–106. http://dx.doi.org/10.3167/arcs.2021.070107.

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While many anthropologists have previously reflected on longitudinal ethnography— for example distinguishing between different categories of longitudinal research, including the ethnographic revisit, either by the same or another researcher, diachronic research projects, involving continuous and sustained engagement over time, or so-called large-scale or multigenerational projects, among others—there has been little reflection on the way particular topics of research might impact on the longitudinal research process. In particular, we argue here that the stakes of longitudinal ethnographic research come to the fore particularly starkly in relation to studies of violence. More specifically, longitudinality potentially both enhances certain risks inherent to carrying out research on violence, while also offering unique opportunities for better understanding the phenomenon more reflexively.

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23

Diaz, Lorenzo J., e Marcelo Viana. "Discontinuity of Hausdorff dimension and limit capacity on arcs of diffeomorphisms". Ergodic Theory and Dynamical Systems 9, n. 3 (settembre 1989): 403–25. http://dx.doi.org/10.1017/s014338570000506x.

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AbstractWe consider one-parameter families of torus diffeomorphisms that bifurcate from global hyperbolic maps (Anosov) to DA maps (derived from Anosov). For an open set of these families, we show that the Hausdorff dimension and limit capacity of the nonwandering set are not continuous across the bifurcation. We also study the behaviour of equilibrium measures near the bifurcation.

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Lai, Shengxiong, Wei Xu, Zhuchuang Yang, Liming Lu, Kun Wang, Sen Feng, Sijian Zhang, Yangkuan Wu e Ben-Xin Wang. "Quad-band terahertz metamaterial absorber using three parallel gold strips surrounded by two identical gold ring arcs". Physica Scripta 97, n. 3 (8 febbraio 2022): 035501. http://dx.doi.org/10.1088/1402-4896/ac4f9c.

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Abstract Quad-band terahertz metamaterial absorber with near-perfect absorption is given in this paper. It is designed by a patterned Au layer and a continuous Au film separated by an insulating dielectric layer, of which the patterned Au layer is consisted of three parallel Au strips (a longer and two shorter) surrounded by two Au ring arcs of the same size. Four separated terahertz absorption peaks with narrow bandwidths and large absorptance are realized. The first three absorption peaks are due to the fundamental modes of the Au strips and the Au ring arcs, while the fourth absorption peak is ascribed to the excitation of three-order resonance in the Au ring arcs. The field distributions of the four absorption peaks are presented to verify their physical mechanisms. The influence of geometrical dimensions of the proposed configuration on the performance of the quad-band light absorption is discussed. Moreover, considering the potential sensing applications, the sensing performance of the proposed absorption device is also explored. The suggested scheme could provide considerable application prospects in selective thermal radiation, spectral imaging, sensing, detecting, electromagnetic stealth, etc.

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Chen, Li Qiang, Jun Xing Wang e Yu Ting Chen. "Numerical Simulation on Backwater Downstream of Aerators in Spillway Tunnel with Ultra-Low Frounde Number Flow". Applied Mechanics and Materials 444-445 (ottobre 2013): 539–43. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.539.

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The backtracking of flow occurs easily in cavity of aeration step in spillway tunnel with a gentle bottom slope and ultra-low Frounde number, and this influences the intake of air, so combined with the spillway tunnel of Chang heba Hydropower Station, four bodily form of aeration steps are chosen to be studied by both numerical simulation and model test based on κ-ε turbulence model, they are continuous aeration step, U-type aeration step + local steep slope, continuous aeration step + circular arc type steep slope and continuous aeration step + ogee curve steep slope, the results show that, the downstream bottom slope of aeration step with suitable ogee curve or circular arcs can efficiently inhibit the backtracking of flow in continuous aeration step, and can efficiently eliminate hydrops in cavity and in the same time can improve the efficiency of aeration. Usually, the results of bottom slope with an ogee curve are better than that with a circular arc.

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Chhabi Lal Bhusal. "A Survey on Models of Flows over Time with Flow Dependent Transit Times". Prāgyik Prabāha 12, n. 1 (23 settembre 2024): 1–13. http://dx.doi.org/10.3126/pp.v12i1.69961.

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Ford and Fulkerson introduce the maximum dynamic flow problems with fixed transit times on the arcs and developed the first well known algorithm that sends maximum flow from the source to the sink by augmenting along s-t paths and prove the maximum amount of flow is equal to the total capacity of the arcs in minimum cut. In flows over time with fixed transit time on the arc, the time it takes to traverse an arc does not depend on the current flow situation on the arc. But in real situation, the flow units travelling on the same arc at the same time do not necessarily experience the same pace, i.e., flow units are in general not entering and leaving an arc in the same order. In this paper, we discuss the time expanded graph for load-dependent and inflow[1]dependent transit times. We also discuss the discrete and continuous time flow, earliest arrival flow and quickest transhipment problem.

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Bostanov, B. О. "Unstressed combined trajectory of robot". Bulletin of the National Engineering Academy of the Republic of Kazakhstan 4, n. 78 (10 gennaio 2020): 29–34. http://dx.doi.org/10.47533/2020.1606-146x.29.

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The problem of forming a smooth combined trajectory of the robot and determining the position of the connection points, providing kinematic and dynamic smoothness conditions, is considered. Mathematical relations are obtained that express the conditions for connecting arcs of a trajectory without a jump in the radii of curvature at the joints. The proposed method provides the formation of complex technical forms and creates on their basis new models of the combined trajectory of a robot of continuous curvature.

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Bostanov, B. О. "Unstressed combined trajectory of robot". Bulletin of the National Engineering Academy of the Republic of Kazakhstan 4, n. 78 (10 gennaio 2020): 29–34. http://dx.doi.org/10.47533/2020.1606-146x.29.

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The problem of forming a smooth combined trajectory of the robot and determining the position of the connection points, providing kinematic and dynamic smoothness conditions, is considered. Mathematical relations are obtained that express the conditions for connecting arcs of a trajectory without a jump in the radii of curvature at the joints. The proposed method provides the formation of complex technical forms and creates on their basis new models of the combined trajectory of a robot of continuous curvature.

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Hoppmann-Baum, Kai, Felix Hennings, Ralf Lenz, Uwe Gotzes, Nina Heinecke, Klaus Spreckelsen e Thorsten Koch. "Optimal Operation of Transient Gas Transport Networks". Optimization and Engineering 22, n. 2 (16 febbraio 2021): 735–81. http://dx.doi.org/10.1007/s11081-020-09584-x.

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AbstractIn this paper, we describe an algorithmic framework for the optimal operation of transient gas transport networks consisting of a hierarchical MILP formulation together with a sequential linear programming inspired post-processing routine. Its implementation is part of the KOMPASS decision support system, which is currently used in an industrial setting. Real-world gas transport networks are controlled by operating complex pipeline intersection areas, which comprise multiple compressor units, regulators, and valves. In the following, we introduce the concept of network stations to model them. Thereby, we represent the technical capabilities of a station by hand-tailored artificial arcs and add them to network. Furthermore, we choose from a predefined set of flow directions for each network station and time step, which determines where the gas enters and leaves the station. Additionally, we have to select a supported simple state, which consists of two subsets of artificial arcs: Arcs that must and arcs that cannot be used. The goal is to determine a stable control of the network satisfying all supplies and demands. The pipeline intersections, that are represented by the network stations, were initially built centuries ago. Subsequently, due to updates, changes, and extensions, they evolved into highly complex and involved topologies. To extract their basic properties and to model them using computer-readable and optimizable descriptions took several years of effort. To support the dispatchers in controlling the network, we need to compute a continuously updated list of recommended measures. Our motivation for the model presented here is to make fast decisions on important transient global control parameters, i.e., how to route the flow and where to compress the gas. Detailed continuous and discrete technical control measures realizing them, which take all hardware details into account, are determined in a subsequent step. In this paper, we present computational results from the KOMPASS project using detailed real-world data.

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Lynds, Roger, e Vahè Petrosian. "Giant Luminous Arcs in Clusters of Galaxies". Symposium - International Astronomical Union 130 (1988): 467–69. http://dx.doi.org/10.1017/s007418090013637x.

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During a program of study of surface brightness of elliptical galaxies in large redshift clusters in 1976 by a video camera at the KPNO 4-meter telescope, we in colaboration with Alan Sandage discovered filamentary and arc-like features in three clusters of galaxies. More recently, the same clusters (Abell 370, Abell 2218, and Cl2244-02) were observed by three different CCD's at the same telescope. These new observations confirm ouir old observations, and being of higher quality, show that the features in two of the clusters (Abell 370 and Cl 2244) form well defined continuous arcs with the following properties: 1)Large nearly circular features (length and radius of curvature ∼100 Kpc) with the center of curvature located near the center of gravity of the cluster.2)Large optical luminosity (≃1011L⊙).3)Bluer than the elliptical galaxies with unexpectedly high ultraviolet emission for Abell 370 giving rise to an unusual spectrum (see figure 1).4)Nearly uniform width along the arc with almost abrupt termination points, indicating a one dimensional structure rather than projection of a portion of a spherical shell.5)the arcs are nearly resolved perpendicular to their length with widths of ≤ 1″ (≤ 6 Kpc). i)In case of Abell 370 the surface brightness is very uniform but the width varies with wavelength, becoming wider toward blue and ultraviolet.ii)In case of CI 2244 there is considerable variation of surface brightness along the arc. We have no information on the variation of the width with wavelength.6)Our data does not show any other unusual features associated with the clusters as a whole or with the giant cD galaxies. These clusters may, however, be unusual in that they seem to have two distinct centers of gravity, this is especially true for Abell 370 which has two almost identical giant cD galaxies instead of the usual clusters dominated by one centrally located cD galaxy.7)Polarization observations show that the arcs are not highly polarized (polarization < 20%).8)From a short exposure spectral observation of C12244 we can only deduce absence of very strong emission lines.

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Lyzzaik, Abdallah. "The geometry of open continuous mappings having two valences between Riemann surfaces". Mathematical Proceedings of the Cambridge Philosophical Society 120, n. 2 (agosto 1996): 309–29. http://dx.doi.org/10.1017/s0305004100074879.

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AbstractAn open continuous function from an open Riemann surface with finite genus and finite number of boundary components into a closed Riemann surface is termed a (p, q)-map, 0 < q < p, if it has a finite number of branch points and assumes every point in the image surface either p or q times, counting multiplicity, with possibly a finite number of exceptions.The object of this paper is to prove that the geometry of any (p, q)-map resembles that of a (p, q)-map whose q-set (the set of image points of f that are taken on exactly q times, counting multiplicity), constitutes a finite set of Jordan arcs or curves (loops). This leads to interesting geometrie results regarding (p, q)-maps without exceptional points. Further, it yields that every (p, q)-map is homotopic to a simplicial (p, q)-map having the same covering properties.

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Thi Minh, NGUYEN, PHAN Huu Lam, NGUYEN Hong Quang, CAO Thanh Nghia, LUONG Ngoc Minh, NGUYEN Thi Kim Thu, NGUYEN Thi Minh Tam, HO Thi Huyen Thuong, VU Dinh Lam e NGUYEN Thi Quynh Hoa. "A SIMPLE DESIGN OF BROADBAND CROSS-POLARIZATION CONVERTER FOR THE THz FREQUENCY RANGE". Vinh University Journal of Science 52, n. 4A (20 dicembre 2023): 28–38. http://dx.doi.org/10.56824/vujs.2023a084.

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A broadband and lightweight polarization converter is proposed for applications in the THz frequency region. The proposed design has a metasurface structure with the dielectric layer modified to a hollow structure to obtain a lightweight design. The unit cell consists of two opposite arcs resonator patches and a continuous metal patch separated by the polyimide substrate layer. The simulated results indicate that the proposed polarized converter achieves a polarization conversion ratio above 93% in the frequency range from 1.6 THz to 5.8 THz with a relative bandwidth of 113.5%.

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Taheri, Ehsan, e John L. Junkins. "How Many Impulses Redux". Journal of the Astronautical Sciences 67, n. 2 (17 dicembre 2019): 257–334. http://dx.doi.org/10.1007/s40295-019-00203-1.

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AbstractA central problem in orbit transfer optimization is to determine the number, time, direction, and magnitude of velocity impulses that minimize the total impulse. This problem was posed in 1967 by T. N. Edelbaum, and while notable advances have been made, a rigorous means to answer Edelbaum’s question for multiple-revolution maneuvers has remained elusive for over five decades. We revisit Edelbaum’s question by taking a bottom-up approach to generate a minimum-fuel switching surface. Sweeping through time profiles of the minimum-fuel switching function for increasing admissible thrust magnitude, and in the high-thrust limit, we find that the continuous thrust switching surface reveals the N-impulse solution. It is also shown that a fundamental minimum-thrust solution plays a pivotal role in our process to determine the optimal minimum-fuel maneuver for all thrust levels. Remarkably, we find that the answer to Edelbaum’s question is not generally unique, but is frequently a set of equal-Δv extremals. We further find, when Edelbaum’s question is refined to seek the number of finite-duration thrust arcs for a specific rocket engine, that a unique extremal is usually found. Numerical results demonstrate the ideas and their utility for several interplanetary and Earth-bound optimal transfers that consist of up to eleven impulses or, for finite thrust, short thrust arcs. Another significant contribution of the paper can be viewed as a unification in astrodynamics where the connection between impulsive and continuous-thrust trajectories are demonstrated through the notion of optimal switching surfaces.

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Konopatskiy, E. V., e A. A. Bezditnyi. "CONJUGATION OF CURVED LINES IN THE POINT CALCULUS". Vestnik komp'iuternykh i informatsionnykh tekhnologii, n. 216 (giugno 2022): 3–11. http://dx.doi.org/10.14489/vkit.2022.06.pp.003-011.

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The paper implements a general approach to conjugate curves in the point calculus, which includes geometric algorithms for conjugating curves and their analytical description in the form of point equations. This is the mathematical basis for building high-performance computer-aided design systems and providing them with the necessary geometric modeling tools. Geometric algorithms for conjugating planar and spatial curves in general form involving, respectively, two or three free functions continuous and deferential within the parameter variation interval are considered. A point definition of tangents for planar and spatial curves is presented, which consists in differentiating the equation of the original curve by the current parameter followed by a parallel transfer of the resulting segment to the tangent point. Directly conjugation is provided by means of arcs of the first order of smoothness. Several examples of the definition of the arcs of the outline in the point calculus and recommendations on their use for the conjugation of curves are presented. The point equations given in the article and the computational algorithms based on them are valid not only for conjugation of curves, but also for straight lines, proceeding from the fact that a straight line is a special case of a zero-curvature curve that does not require a tangent to be constructed. The prospect of further research is for the conjugation of surface bays, in which two tangents to the original surface bays will form surface bays with cross-sections in the form of arcs of the outline of the chosen shape.

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Park, Dong Cheul, Chan Gyu Hwang e Do Soon Kwon. "Smart Learning for National Technical Qualifications ARCS Motivation Theory is Interactive, Immersive Learning, Research Influence of Continuous use with Pleasure". Information Systems Review 17, n. 2 (31 agosto 2015): 101–32. http://dx.doi.org/10.14329/isr.2015.17.2.101.

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AMROUN, ABDELHAMID. "Equidistribution results for geodesic flows". Ergodic Theory and Dynamical Systems 34, n. 3 (4 gennaio 2013): 742–64. http://dx.doi.org/10.1017/etds.2012.153.

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AbstractUsing the works of Mañé [On the topological entropy of the geodesic flows.J. Differential Geom.45(1989), 74–93] and Paternain [Topological pressure for geodesic flows.Ann. Sci. Éc. Norm. Supér.(4)33(2000), 121–138] we study the distribution of geodesic arcs with respect to equilibrium states of the geodesic flow on a closed manifold, equipped with a$\mathcal {C}^{\infty }$Riemannian metric. We prove large-deviation lower and upper bounds and a contraction principle for the geodesic flow in the space of probability measures of the unit tangent bundle. We deduce a way of approximating equilibrium states for continuous potentials.

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Mhamdi, Lotfi, Lobna Belkacem, Hedi Dhouibi e Zineb Simeu Abazi. "Using Hybrid Automata for Diagnosis of Hybrid Dynamical Systems". International Journal of Electrical and Computer Engineering (IJECE) 5, n. 6 (1 dicembre 2015): 1396. http://dx.doi.org/10.11591/ijece.v5i6.pp1396-1406.

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Physical systems can fail. For this reason the problem of identifying and reacting to faults has received a large attention in the control and computer science communities. In this paper we study the fault diagnosis problem and modeling of Hybrid Dynamical Systems (HDS). Generally speaking, HDS is a system mixing continuous and discrete behaviors that cannot be faithfully modeled neither by using formalism with continuous dynamics only nor by a formalism including only discrete dynamics. We use the well known framework of hybrid automata for modeling hybrid systems, because they combine the continous and discretes parts on the same structure. Hybrid automaton is a states-transitions graph, whose dynamic evolution is represented by discretes and continous steps alternations, also, continous evolution happens in the automaton apexes, while discrete evolution is realized by transitions crossing (arcs) of the graph. Their simulation presents many problems mainly the synchronisation between the two models. Stateflow, used to describe the discrete model, is co-ordinated with Matlab, used to describe the continuous model. This article is a description of a case study, which is a two tanks system.

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Lawrence, J. R., e R. A. Snyder. "Feeding behaviour and grazing impacts of a Euplotes sp. on attached bacteria". Canadian Journal of Microbiology 44, n. 7 (1 luglio 1998): 623–29. http://dx.doi.org/10.1139/w98-057.

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The locomotory and feeding responses of a Euplotes sp. to attached populations of Vibrio natriegens and Pseudomonas fluorescens in a continuous flow system were analyzed by computer image analysis of video microscopy recordings. Upon entry into the chamber, the ciliates moved in long continuous arcs 300 µm in length during which time no bacteria were consumed. As feeding began, the average path length shortened, the arcs became tighter, and the ciliates changed direction more frequently. The feeding activity of the Euplotes appeared to be gregarious, being concentrated in patches within the biofilm of attached bacteria. It was also noted that the feeding effort targeted patches previously visited by other Euplotes, despite reduced bacterial density relative to the surrounding field of attached bacteria. This focused and intense feeding activity resulted in localized zones of nearly complete clearance within the attached bacterial populations. Loss of bacteria and averaged ciliate presence within feeding patches were determined from digitized time series images and discrimination thresholds for particle size. These data were used to determine grazing rates indicating that Euplotes sp. removed 120 V. natriegens cells·ciliate1·h1 and up to 882 P. fluorescens cells·ciliate1·h1. However, surface clearance rates for Euplotes sp. grazing on V. natriegens and P. fluorescens were 0.02 and 0.03 mm2·ciliate1·h1, respectively, indicating that surface grazing pressure was fairly consistent within the patches of intense feeding activity. The effect of such intense localized feeding behaviour on attached or biofilm bacteria would be to increase spatial and temporal heterogeneity within biofilms. Key words: digital image analysis, Euplotes, grazing, biofilms.

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Stojanović, Igor, Ivona Brajević, Predrag S. Stanimirović, Lev A. Kazakovtsev e Zoran Zdravev. "Application of Heuristic and Metaheuristic Algorithms in Solving Constrained Weber Problem with Feasible Region Bounded by Arcs". Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/8306732.

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The continuous planar facility location problem with the connected region of feasible solutions bounded by arcs is a particular case of the constrained Weber problem. This problem is a continuous optimization problem which has a nonconvex feasible set of constraints. This paper suggests appropriate modifications of four metaheuristic algorithms which are defined with the aim of solving this type of nonconvex optimization problems. Also, a comparison of these algorithms to each other as well as to the heuristic algorithm is presented. The artificial bee colony algorithm, firefly algorithm, and their recently proposed improved versions for constrained optimization are appropriately modified and applied to the case study. The heuristic algorithm based on modified Weiszfeld procedure is also implemented for the purpose of comparison with the metaheuristic approaches. Obtained numerical results show that metaheuristic algorithms can be successfully applied to solve the instances of this problem of up to 500 constraints. Among these four algorithms, the improved version of artificial bee algorithm is the most efficient with respect to the quality of the solution, robustness, and the computational efficiency.

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Gîrbacia, Teodora, Andrei Margarit, Simion Mădălin e Gheorghe Mogan. "Path and Trajectory Planning for Vehicles with Navigation Assistants". Applied Mechanics and Materials 811 (novembre 2015): 300–304. http://dx.doi.org/10.4028/www.scientific.net/amm.811.300.

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For autonomous vehicles an important problem is to plan and accurately follow the optimal trajectory between the start point and the target, without collision with the obstacles placed in the environment. In order to obtain a continuous motion along the planned path for a vehicle with navigation assistants, especially when avoiding obstacles, the transition between a straight segment and circle arcs has to be done through using an additional curve. This paper present an algorithm based on clothoid curves for optimal steering using as case a vehicle with navigation assistants. The developed algorithm has been tested in a real environment and results have been presented.

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FERRAZ, A. "RENORMALIZATION GROUP OF A TWO-DIMENSIONAL PATCHED FERMI SURFACE". Modern Physics Letters B 17, n. 04 (20 febbraio 2003): 167–74. http://dx.doi.org/10.1142/s021798490300507x.

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Using the renormalization group we calculate the single particle Green's function G and the momentum occupation function [Formula: see text] for a quasiparticle in a two-dimensional Fermi Surface (FS) composed of four symmetric patches with both flat and curved arcs in [Formula: see text]-space. We show that G develops an anomalous dimension as a result of the vanishing of the quasiparticle weight at the FS. [Formula: see text] is a continuous function of [Formula: see text] with an infinite slope at FS for CU*2/(1 - CU*2) < 1. This result resembles a Luttinger liquid and indicates the breakdown of Fermi liquid theory in this regime.

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Hamza, FAKHAR, LAMRABET Mohammed, ECHANTOUFI Noureddine, OUADRHIRI Karim, EL KHATTABI Khalid e AJANA Lotfi. "ChatGPT as an intelligent self-Continuous Professional Development tool for teachers". Statistics, Optimization & Information Computing 13, n. 2 (2 ottobre 2024): 488–507. https://doi.org/10.19139/soic-2310-5070-2145.

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Artificial intelligence, with its vast capabilities, has permeated various sectors of society, including education. This technological revolution has brought significant changes to both teaching and learning processes. This study aims to assess teachers' motivation to utilize AI-based tools, specifically ChatGPT, as a means of self-professional development to aid in the preparation of their pedagogical tasks. To this end, an online training session on the use of ChatGPT-4 was conducted with 41 physics teachers in the Fez-Meknes region of Morocco. During this training, teachers prepared lessons using both traditional and AI-enhanced methods. To measure their motivation towards the intelligent method, the IMMS-ARCS survey -based on four factors (Attention, Relevance, Confidence, and Satisfaction)- was employed, a global Alpha Cronbach=0.901 indicates an excellent internal consistency between the 36 items. The results indicate that teachers generally exhibit a positive attitude towards using ChatGPT as an innovative tool that can assist and streamline their teaching tasks. Additionally, the findings reveal that the four motivational factors are positively correlated, with higher values of these predictors indicating greater overall teachers’ motivation to adopt ChatGPT-4 as an intelligent tool for self-development of a new skills to improve their competencies, ultimately, enhancing students’ outcomes.

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Wang, Xuan, Momiao Zhou, Zhengqiong Liu e Zhizhong Ding. "On Minimum Parking Space Required by Automatic Parallel Parking". Sensors 22, n. 3 (20 gennaio 2022): 795. http://dx.doi.org/10.3390/s22030795.

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Automatic parking system has been widely equipped on manual driving vehicles for decades. Due to the limited environment sensing ability and not-accurate-enough positioning system, however, it usually requires a very large redundant space for a car to accomplish one successful parking maneuver. There would be two differences in the coming era of automatic driving: (1) sufficiently accurate perception and positioning systems can be expected to be available, and (2) the number of parking trials could be large when parking without passengers on the vehicle. Under such circumstances, it is quite important for the vehicle to know exactly whether the external and internal spaces are large enough for parking and how the minimum number of trials will be required. This paper presents closed-form solutions of minimum internal and external space required for automatic parallel parking and the corresponding trials if the parking is based on circular arcs. On the other hand, it is also very useful for the vehicle to know the required minimum space if only one trial is allowed, for which the solutions are presented both for circular arcs and continuous-curvature curves based parking, respectively. To the best of our knowledge, there is no so far systematic analysis and research on the issue addressed in this paper.

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Chen, Yuhao, Yalun Li, Juan Wang, Languang Lu, Hewu Wang, Minghai Li, Wenqiang Xu, Chao Shi e Cheng Li. "Characterization of Breakdown Arcs Induced by Venting Particles Generated by Thermal Runaway of Large-Capacity Ternary Lithium-Ion Batteries". Electronics 13, n. 16 (10 agosto 2024): 3168. http://dx.doi.org/10.3390/electronics13163168.

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In recent years, with the continuous growth in power demand, lithium-ion batteries (LIBs) have become an indispensable component of various electronic devices, transportation vehicles, and energy systems. The safety performance of LIBs is one of the most significant issues facing their continued development. In battery systems, the presence of arcs constitutes a significant safety hazard that necessitates attention; the thermal runaway (TR) of LIBs releases a large quantity of particles with elevated temperature and high velocity, probably resulting in arc failures. Changes in the insulation structure inside battery packs and the accumulation of particulate matter resulting from the TR of battery cells are potential causes of arc-induced disasters. In this study, we utilized fully charged 71 Ah ternary LIB Li (Ni0.8Co0.1Mn0.1) O2 (NCM811) pouch cell samples and collected the vented particles in an inert atmosphere after TR. All the settled particles were classified into six groups; by conducting experiments with different particle sizes, electrode spacings, and circuit loads, the patterns of the particle-induced arcs were understood. The results indicate that as the particle size increases, the critical breakdown voltage decreases. Regarding electrode spacing and circuit load resistance, larger values require higher critical breakdown voltages. The research results provide valuable guidance for the electrical protection and safety design of battery systems.

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Dieudonne, Kabange Imbanga, Mwila Sompwe Jacques, Mututa Ilunga Peguy, Ilunga Mweze Arsene e Mr Papy Kitengie Musawu. "Optimization of the Fuse Protection System of The BT Electrical Distribution Network in Likasi in Order to Reduce Electric Arcs And Expenses". International Journal of Scientific Research and Management (IJSRM) 13, n. 01 (8 gennaio 2025): 1845–61. https://doi.org/10.18535/ijsrm/v13i01.ec01.

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The study on the optimization of the fuse protection system of the BT electrical distribution network in Likasi has identified the main causes of the recurring electric arcs and the high expenses related to this system. The failures of the protection system are mainly due to a lack of coordination of the protections and a suboptimal selectivity of the installed fuses. This results in frequent power outages and significant maintenance costs for the network operator. To address this situation, technical and organizational solutions have been proposed. These include strengthening the coordination of the protections, optimizing the selectivity of the fuses and improving the preventive maintenance of the network. These improvements should significantly reduce the failures of the protection system, thus benefiting consumers in terms of the reliability of the electricity supply, and the operator in terms of controlling operating costs. Beyond these immediate solutions, the optimization of the fuse protection system is part of a continuous improvement perspective, particularly with the emergence of smart monitoring and control technologies. The progressive integration of more efficient protection devices, such as fast-acting fuses or electronic circuit breakers, will also help reduce the risks of electric arcs and optimize network maintenance. In the longer term, this optimization approach will have to adapt to the challenges of the local energy transition. In addition, an innovative solution was considered as part of this study: the recycling of zinc envelopes from used batteries for the manufacture of replacement fuses. This approach would not only reduce electric arcs, but also significantly reduce the costs associated with the purchase of new fuses. The dimensioning of these zinc fuses, based on the characteristics of the battery envelopes, would be an interesting avenue to explore to further optimize the protection system of the BT network in Likasi.

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Batista, Guilherme V., Cassius T. Scarpin, José E. Pécora e Angel Ruiz. "A New Ant Colony Optimization Algorithm to Solve the Periodic Capacitated Arc Routing Problem with Continuous Moves". Mathematical Problems in Engineering 2019 (28 luglio 2019): 1–12. http://dx.doi.org/10.1155/2019/3201656.

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This paper describes a variant of the Periodic Capacitated Arc Routing Problem for inspections in a railroad network. Inspections are performed by vehicles over a time horizon on which some stretches need evaluation more frequently than others due to its use. Each car can evaluate one stretch per day without being attached to a depot; at each day, the shift may start and end at different locations. This characterizes the problem as the Periodic Capacitated Arc Routing Problem with Continuous Moves in which firstly the delays on attendances are minimized and, second, the displacement costs. We present a mathematical model and an Ant Colony Optimization algorithm to solve the problem. The use of a local search procedure and some principles of Granular Tabu Search is crucial for the algorithm’s performance. The numerical results are promising, especially for critical situations where the arcs’ needs are close to the total vehicles’ capacity.

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Nitulescu, Mircea. "Experiments for Performance Evaluation of a Mobile Robot Trajectory Tracking". Applied Mechanics and Materials 162 (marzo 2012): 302–7. http://dx.doi.org/10.4028/www.scientific.net/amm.162.302.

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Generally, the path given by the 2D global path planner is a complex trajectory concerning straight lines, circular arcs, quick turning motion or lane change motion, but in the simplest case, the trajectory can be a polygonal shape. For the case of a differential wheeled mobile robot without spin motions, this paper presents and analyzes the real continuous evolution of the robot between two adjacent straight line of a polygonal rote, concerning different angles. For the same model of the robot, the control uses alternatively two different algorithms: the first one is a classical solution in path tracking control and the second one is an algorithm based on a smooth curve function.

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M Rosedi, Shamsul Rizal. "Evaluating students’ level of motivation in learning maritime English during the Movement Control Order (MCO) period: Preliminary findings on online distance learning of an STCW course". Journal of Research, Policy & Practice of Teachers & Teacher Education 11, n. 2 (22 dicembre 2021): 139–51. http://dx.doi.org/10.37134/jrpptte.vol11.2.10.2021.

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The global pandemic of Covid-19 has affected the teaching and learning of the STCW courses (Standards of Training, Certification and Watch-keeping for Seafarers) which witnessed the drastic move from normal face-to-face facilitation to full online and distance learning (ODL). This new paradigm shift has resulted in significant changes as well as immense challenges to students who experienced this crisis for the first time. Hence, the study aims to discover students’ motivation level in adapting to the new environment of online learning as experienced by semester 2 students in Maritime English classes via quantitative study adopted Keller’s ARCS Model of Motivation survey administered on 78 respondents. The data collected were analysed and the results showed high level of students’ motivation despite having to undergo challenges in online distance learning during the MCO. Moreover, the four elements of the ARCS Model tested in the experiment indicated very high scores in students’ engagement, confidence, motivation, and satisfaction. This preliminary study has helped to provide a new perspective on online learning as well as students’ motivation to the maritime education and training institutions. Hence, it is hoped that the findings could help them to make continuous quality improvement in pedagogical, technological adaptation and assessment aspects for the benefit of students and stakeholders of the maritime industry.

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De Franco, A., M. Comunian, E. Fagotti, F. Grespan, K. Hayashi, K. Hirosawa, K. Kondo et al. "RF conditioning towards continuous wave of the RFQ of the Linear IFMIF Prototype Accelerator". Journal of Physics: Conference Series 2687, n. 5 (1 gennaio 2024): 052019. http://dx.doi.org/10.1088/1742-6596/2687/5/052019.

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Abstract The Linear IFMIF Prototype Accelerator (LIPAc) is designed to accelerate 125mA of deuteron beam to 9MeV in continuous wave (CW). The superconductive RF Linac has not yet been installed and the final accelerating stage now under commissioning is the RFQ. This system has been designed and developed by INFN (Italy) before installation in QST (Japan). The RFQ is the longest in the World with its 9.8m and requires RF power injection from 8 independent and synchronized coupler ports. LIPAc demonstrated the acceleration of 125mA deuteron beam at 5MeV for 1ms with a 1s repetition period in 2019. A fundamental milestone to extend beam operations to CW is the completion of the RFQ cavity RF conditioning up to CW. This work presents the strategy followed to successfully reach CW RF injection at 80% of the nominal 132kV vane voltage. The field distribution correction scheme (acting on cooling system at various power levels) was successfully verified. We discuss as well the main challenges encountered on the way, which include updates of the RF system, failure of a circulator (by arcs) and the damages occurred on some of the RF couplers. Finally, the recent status and outlook will be provided.

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Stoyanov, Stiliyan. "APPROXIMATION METHOD FOR DISCOVERY OF ANOMALOUS SIGNALS IN OPTICAL-ELECTRONIC DEVICES". Journal Scientific and Applied Research 17, n. 1 (15 novembre 2019): 9–12. http://dx.doi.org/10.46687/jsar.v17i1.266.

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The research is about registration of signals by optic-electronic devices. The subject of the current work is research of the approximative methods capability to discover anomalous signals in an impulse photometric device. The impulse photometric device ensures a high dimensional and timely resolution of the intensity distribution by natural optic emissions in the earth atmosphere and also light interference near the orbital station. The high spectral sensitivity and the dimensional resolution enable the research of fast processes, including pulsating polar lights, polar arcs, etc. When we discover and identify distant objects, the input informational signal is a continuous process with medium dispersion and correlation function. In the optic-electronic system the signal is a combination of equal values in time.

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