Logarithmic spiral ≈ Logarithmic spiral
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Transient spiral structure and the disc velocity substructure in Gaia DR2 Open
The second data release from ESA's Gaia mission has revealed many ridge-like\nstructures in the velocity distribution of the Milky Way. We show that these\ncan arise naturally from winding transient spiral structure that is commonly\nseen …
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An Improved Whale Optimization Algorithm Based on Different Searching Paths and Perceptual Disturbance Open
Whale optimization algorithm (WOA) is a swarm intelligence optimization algorithm inspired by humpback whale hunting behavior. WOA has many similarities with other swarm intelligence algorithms (PSO, GWO, etc.). WOA’s unique search mechani…
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Multiple phase spirals suggest multiple origins in <i>Gaia</i> DR3 Open
Gaia Data Release 2 revealed that the Milky Way contains significant indications of departures from equilibrium in the form of asymmetric features in the phase space density of stars in the Solar neighbourhood. One such feature is the z–vz…
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Thermal Infrared Imaging of MWC 758 with the Large Binocular Telescope: Planetary-driven Spiral Arms? Open
Theoretical studies suggest that a giant planet around the young star MWC 758 could be responsible for driving the spiral features in its circumstellar disk. Here, we present a deep imaging campaign with the Large Binocular Telescope with …
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Orbital tori for non-axisymmetric galaxies Open
Our Galaxy's bar makes the Galaxy's potential distinctly non-axisymmetric. All orbits are affected by non-axisymmetry, and significant numbers are qualitatively changed by being trapped at a resonance with the bar. Orbital tori are used to…
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A modified logarithmic spiral method for determining passive earth pressure Open
In this study, a modified logarithmic spiral method is proposed to determine the passive earth pressure and failure surface of cohesionless sloping backfill, with presence of wall–soil interface friction. The proposed method is based on a …
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The Euler spiral of rat whiskers Open
Rat whiskers curve naturally as Euler spirals.
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Magnetic spiral arms in galaxy haloes Open
We seek the conditions for a {\it steady} mean field galactic dynamo. The parameter set is reduced to those appearing in the $\alpha^2$ and $\alpha/\omega$ dynamo, namely velocity amplitudes, and the ratio of sub-scale helicity to diffusiv…
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Planar Ultrawideband Circularly Polarized Cosine Slot Archimedean Spiral Antenna for Partial Discharge Detection Open
Design and experimental verification of an ultrawideband planar circularly polarized ultrahigh frequency (UHF) sensor is presented for detection of partial discharge (PD) activities in high voltage (HV) equipment. The proposed sensor is ca…
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Multi-Objective Low-Thrust Interplanetary Trajectory Optimization Based on Generalized Logarithmic Spirals Open
The multi-objective optimal design of low-thrust multigravity-assist trajectories is formulated within the hybrid optimal control framework. A new automated solution strategy for this problem is proposed in this Paper based on a two-step a…
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Active earth pressure of narrow cohesive backfill on rigid retaining wall of rotation about the bottom Open
Retaining wall construction often encounters narrow cohesive backfill and the traditional theories are no longer suitable. Hence, analytical solutions for active earth pressure of narrow cohesive backfill on a rigid retaining wall rotating…
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The interaction of a walking droplet and a submerged pillar: From scattering to the logarithmic spiral Open
Millimetric droplets may walk across the surface of a vibrating fluid bath, propelled forward by their own guiding or “pilot” wave field. We here consider the interaction of such walking droplets with a submerged circular pillar. While sim…
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THE DYNAMICAL RELATIONSHIP BETWEEN THE BAR AND SPIRAL PATTERNS OF NGC 1365 Open
Theories that attempt to explain the dynamical relationship between bar and spiral patterns in galactic disks make different predictions about the radial profile of the pattern speed. These are tested for the H-alpha bar and spiral pattern…
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Broadband spin‐controlled focusing via logarithmic‐spiral nanoslits of varying width Open
This work presents analytical, numerical and experimental demonstrations of light diffracted through a logarithmic spiral (LS) nanoslit, which forms a type of switchable and focus‐tunable structure. Owing to a strong dependence on the inci…
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Numerical Study of Shock Wave Attenuation in Two-Dimensional Ducts Using Solid Obstacles: How to Utilize Shock Focusing Techniques to Attenuate Shock Waves Open
Research on shock wave mitigation in channels has been a topic of much attention in the shock wave community. One approach to attenuate an incident shock wave is to use obstacles of various geometries arranged in different patterns. This w…
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Segmented strings in AdS 3 Open
We study segmented strings in flat space and in $AdS_3$. In flat space, these\nwell known classical motions describe strings which at any instant of time are\npiecewise linear. In $AdS_3$, the worldsheet is composed of faces each of which\…
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Flow Characteristics and Hydraulic Lift of Coandă Effect-Based Pick-Up Method for Polymetallic Nodule Open
The deep-sea mining vehicle is the main component of the undersea exploitation system, which gathers polymetallic nodules with its professionally designed seabed collector. The Coandă effect-based collecting method is an improved hydraulic…
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Geometric Aspects and Testing of the Galactic Center Distance Determination from Spiral Arm Segments Open
We consider the problem of determining the geometric parameters of a Galactic\nspiral arm from its segment by including the distance to the spiral pole, i.e.,\nthe distance to the Galactic center ($R_0$). The question about the number of\n…
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Classifying and modelling spiral structures in hydrodynamic simulations of astrophysical discs Open
DHF, FGR-F and IAB gratefully acknowledge support from the ECOGAL project, grant agreement 291227, funded by the European Research Council under ERC-2011-ADG.
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Ultra-Wideband Low-Cost High-Efficiency Cavity-Backed Compound Spiral Antenna Open
A low-cost high-efficiency ultra-wideband (UWB) cavity-backed spiral antenna is proposed. It employs an equiangular spiral enclosed by an Archimedean spiral and it is fed through a tapered microstrip balun. A center-raised cylindrical abso…
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Interfacial metric mechanics: stitching patterns of shape change in active sheets Open
A flat sheet programmed with a planar pattern of spontaneous shape change will morph into a curved surface. Such metric mechanics is seen in growing biological sheets, and may be engineered in actuating soft matter sheets such as phase-cha…
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On the generation of spiral-like paths within planar shapes Open
We simplify and extend prior work by Held and Spielberger [CAD 2009, CAD&A 2014] to obtain spiral-like paths inside of planar shapes bounded by straight-line segments and circular arcs: We use a linearization to derive a simple algorithm t…
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Galactic Density and Evolution Based on the Virial Theorem, Energy Minimization, and Conservation of Angular Momentum Open
Spiral galaxies are spinning, internally densified objects. The Virial Theorem explains galactic rotation curves via its linkage of the rotation rate to the gravitational self-potential (Ug) and the moment of inertia of oblate spheroids. W…
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The Complex Dynamics of the Precessing Vortex Rope in a Straight Diffuser Open
The decelerated swirling flow in the discharge cone of Francis turbines operated at partial discharge develops a self-induced instability with a precessing helical vortex (vortex rope). In an axisymmetric geometry, this phenomenon is expec…
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The Logarithmic Spiral of Networks of Care for Expectant Families in Rural Nepal: A Descriptive Case Study Open
This case study utilizes the four domains of effective Networks of Care (NOC) as a lens to describe the suite of interventions of a biosocial approach to maternal and neonatal health services in rural Nepal: The Network of Safety model, cr…
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Smooth path planning via cubic GHT-Bézier spiral curves based on shortest distance, bending energy and curvature variation energy Open
In this article, an algorithm to obtain a smooth path (free from obstacles) that can be optimized by shortest path distance, bending energy and curvature variation energy will be presented. Previously, scholars used various tools to genera…
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Numerical and Experiment Investigation on Novel Guide Vane Structures of Turbo Air Classifier Open
In this paper, three types of air guide vanes are designed: direct-type, L-type, and logarithmic spiral type, respectively. ANSYS-FLUENT 20.0 is used to numerically simulate the internal flow field of turbo air classifier by novel differen…
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A Model of Deformation Geometry in Pipe Bending Processes Open
The paper presents a complete set of geometric relationships for logarithmic measures of longitudinal, circumferential and radial strains arising in bending of thin- and thick-walled pipes. The strain can be determined at each plane parall…
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A Pseudodynamic Approach of Seismic Active Pressure on Retaining Walls Based on a Curved Rupture Surface Open
Reasonable determination of the magnitude and distribution of dynamic earth pressure is one of the major challenges in the seismic design of retaining walls. Based on the principles of pseudodynamic method, the present study assumed that t…
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Spiral chain models of two-dimensional turbulence Open
Reduced models, mirroring self-similar, fractal nature of two-dimensional turbulence, are proposed, using logarithmic spiral chains, which provide a natural generalization of shell models to two dimensions. In a turbulent cascade, where ea…