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Journal articles on the topic 'Logarithmic coordinates'

Author: Grafiati

Published: 2 June 2025

Last updated: 31 July 2025

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1

Rigbi, Zvi. "Graphical representation on logarithmic triangular coordinates." Journal of Chemical Education 62, no. 10 (1985): 855. http://dx.doi.org/10.1021/ed062p855.

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2

Avakov, V. A. "Fatigue Reliability Functions in Semilogarithmic Coordinates." Journal of Mechanical Design 113, no. 3 (1991): 352–58. http://dx.doi.org/10.1115/1.2912789.

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In the previous publication [2], the transformation between fatigue life and strength distribution was established using double-logarithmic coordinate system (InN-InS). Here, a similar transformation is established using a semilogarithmic (InN-S) coordinate system. It is assumed that the set of S = Sj (N/Qj) (j = 1,2,...,p) relations, plotted in the InN-S coordinates, becomes a family of parallel straight lines. With the aid of the developed orthogonal relations, lognormal, Weibull and three-parameter logweibull life distributions have been transformed into normal, asymptotic type 1 of smalles

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3

Campos, L. M. B. C., and P. J. S. Gil. "On spiral coordinates with application to wave propagation." Journal of Fluid Mechanics 301 (October 25, 1995): 153–73. http://dx.doi.org/10.1017/s0022112095003843.

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We introduce a possibly new system of orthogonal curvilinear coordinates, whose coordinate curves are logarithmic spirals in the plane, supplemented by a cylindrical coordinate for three dimensions. It is shown that plane spiral coordinates form a oneparameter family, with equal scale factors along the two orthogonal coordinate curves, and constant Christoffel symbols. The equations of magnetohydrodynamics, which include those of fluid mechanics, are written in spiral coordinates and used to find a state of magnetohydrostatic equilibrium under a radial gravity field and spiral magnetic field,

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4

Tymofijeva, Nadiya К. "Sign Combinatorial Spaces, Finite Sequences and Logarithmic Spirals." Control Systems and Computers, no. 1 (297) (2022): 32–43. http://dx.doi.org/10.15407/csc.2022.01.032.

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Introduction. Sign combinatorial spaces that exist in two states: convolute (tranquility) and deployed (dynamics), are considered. Spaces, in particular biological, physical, informational and some others, for which the axioms of sign combinatorial spaces, are valid, have a combinatorial nature. When they are deployed, combinatorial numbers (Fibonacci numbers) are formed, through which logarithmic spirals appear in living nature. These spirals are formed due to the finite sequences that take place during the deployment of the agreed spaces and which are presented geometrically using polar coor

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Turski, Jacek. "Robotic Vision with the Conformal Camera: Modeling Perisaccadic Perception." Journal of Robotics 2010 (2010): 1–16. http://dx.doi.org/10.1155/2010/130285.

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Humans make about 3 saccades per second at the eyeball's speed of 700 deg/sec to reposition the high-acuity fovea on the targets of interest to build up understanding of a scene. The brain's visuosaccadic circuitry uses the oculomotor command of each impending saccade to shift receptive fields (RFs) to cortical locations before the eyes take them there, giving a continuous and stable view of the world. We have developed a model for image representation based on projective Fourier transform (PFT) intended for robotic vision, which may efficiently process visual information during the motion of

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6

Marton, Katalin. "Logarithmic Sobolev inequalities in discrete product spaces." Combinatorics, Probability and Computing 28, no. 06 (2019): 919–35. http://dx.doi.org/10.1017/s0963548319000099.

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AbstractThe aim of this paper is to prove an inequality between relative entropy and the sum of average conditional relative entropies of the following form: for a fixed probability measure q on , ( is a finite set), and any probability measure on , (*) $$D(p||q){\rm{\le}}C \cdot \sum\limits_{i = 1}^n {{\rm{\mathbb{E}}}_p D(p_i ( \cdot |Y_1 ,{\rm{ }}...,{\rm{ }}Y_{i - 1} ,{\rm{ }}Y_{i + 1} ,...,{\rm{ }}Y_n )||q_i ( \cdot |Y_1 ,{\rm{ }}...,{\rm{ }}Y_{i - 1} ,{\rm{ }}Y_{i + 1} ,{\rm{ }}...,{\rm{ }}Y_n )),} $$ where pi(· |y1, …, yi−1, yi+1, …, yn) and qi(· |x1, …, xi−1, xi+1, …, xn) denote the lo

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7

Das, Tuhin, and Ranjan Mukherjee. "Reconfiguration of a Rolling Sphere: A Problem in Evolute-Involute Geometry." Journal of Applied Mechanics 73, no. 4 (2005): 590–97. http://dx.doi.org/10.1115/1.2164515.

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This paper provides a new perspective to the problem of reconfiguration of a rolling sphere. It is shown that the motion of a rolling sphere can be characterized by evolute-involute geometry. This characterization, which is a manifestation of our specific selection of Euler angle coordinates and choice of angular velocities in a rotating coordinate frame, allows us to recast the three-dimensional kinematics problem as a problem in planar geometry. This, in turn, allows a variety of optimization problems to be defined and admits infinite solution trajectories. It is shown that logarithmic spira

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8

STARK, DUDLEY. "Explicit Limits of Total Variation Distance in Approximations of Random Logarithmic Assemblies by Related Poisson Processes." Combinatorics, Probability and Computing 6, no. 1 (1997): 87–105. http://dx.doi.org/10.1017/s0963548396002775.

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Assemblies are labelled combinatorial objects that can be decomposed into components. Examples of assemblies include set partitions, permutations and random mappings. In addition, a distribution from population genetics called the Ewens sampling formula may be treated as an assembly. Each assembly has a size n, and the sum of the sizes of the components sums to n. When the uniform distribution is put on all assemblies of size n, the process of component counts is equal in distribution to a process of independent Poisson variables Zi conditioned on the event that a weighted sum of the independe

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9

LI Lang, ZHOU Shiyun, GAO Chunqing, and FU Shiyao. "Log-polar transformation data decoding for orbital angular momentum shift keying." Acta Physica Sinica 74, no. 6 (2025): 0. https://doi.org/10.7498/aps.74.20241612.

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Orbital angular momentum (OAM), as a novel high-dimensional degree of freedom, offering significantly potential for optical communication in increasing the system channel capacity and addressing the scarcity of communication resources. However, the effective recognition and detection of OAM modes are the core challenges for achieving efficient communication in such systems. This paper presents an OAM decoding system based on log-polar coordinate transformation, consisting of a designed coordinate transformation device, a phase corrector, and a Fourier transform lens. The coordinate transformat

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10

Nakajima, Yoshitaka, Takashi Tsumura, Seiichi Matsuura, Hiroyuki Minami, and Ryunen Teranishi. "Dynamic Pitch Perception for Complex Tones Derived from Major Triads." Music Perception 6, no. 1 (1988): 1–20. http://dx.doi.org/10.2307/40285413.

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A new type of complex tone that demonstrates pitch circularity is described. For such tones, the spectral envelope is trapezoidal on the coordinates of logarithmic frequency and logarithmic amplitude, and remains constant. The components of each tone form a major triad within each octave. The component frequencies were increased by steps of 1/10 octave from tone to tone, until the first tone was obtained again. According to our paired comparison experiments for pitch, which were analyzed using the multidimensional scaling technique, two kinds of pitch circularities appear. One group of subject

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11

Huber, Johannes, and Bernd Matschkal. "Spherical logarithmic quantization and its application for DPCM." Facta universitatis - series: Electronics and Energetics 17, no. 2 (2004): 165–84. http://dx.doi.org/10.2298/fuee0402165h.

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A new method for efficient digitizing analog signals while preserving the original waveform as close as possible with respect to the relative quantization error is presented. Logarithmic quantization is applied to short vectors of samples represented in sphere coordinates. The resulting advantages, i.e. a constant Signal-to-Noise Ratio over a very high dynamic range at a small loss with respect to rate-distortion theory are discussed. In order to increase the Signal-to-Noise Ratio (SNR) by exploitation of correlations within the source signal, a method of combining differential pulse code modu

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12

Mizuno, Yoshinori, and Javier Jiménez. "Wall turbulence without walls." Journal of Fluid Mechanics 723 (April 16, 2013): 429–55. http://dx.doi.org/10.1017/jfm.2013.137.

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AbstractWe perform direct numerical simulations of turbulent channels whose inner layer is replaced by an off-wall boundary condition synthesized from a rescaled interior flow plane. The boundary condition is applied within the logarithmic layer, and mimics the linear dependence of the length scales of the velocity fluctuations with respect to the distance to the wall. The logarithmic profile of the mean streamwise velocity is recovered, but only if the virtual wall is shifted to a position different from the location assumed by the boundary condition. In those shifted coordinates, most flow p

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DIXIT, SHIVSAI AJIT, and O. N. RAMESH. "Pressure-gradient-dependent logarithmic laws in sink flow turbulent boundary layers." Journal of Fluid Mechanics 615 (November 25, 2008): 445–75. http://dx.doi.org/10.1017/s0022112008004047.

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Experiments were done on sink flow turbulent boundary layers over a wide range of streamwise pressure gradients in order to investigate the effects on the mean velocity profiles. Measurements revealed the existence of non-universal logarithmic laws, in both inner and defect coordinates, even when the mean velocity descriptions departed strongly from the universal logarithmic law (with universal values of the Kármán constant and the inner law intercept). Systematic dependences of slope and intercepts for inner and outer logarithmic laws on the strength of the pressure gradient were observed. A

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14

Karaiev, Artem, and Elena Strelnikova. "Singular integrals in axisymmetric problems of elastostatics." International Journal of Modeling, Simulation, and Scientific Computing 11, no. 01 (2020): 2050003. http://dx.doi.org/10.1142/s1793962320500038.

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Singular integral equations arisen in axisymmetric problems of elastostatics are under consideration in this paper. These equations are received after applying the integral transformation and Gauss–Ostrogradsky’s theorem to the Green tensor for equilibrium equations of the infinite isotropic medium. Initially, three-dimensional problems expressed in Cartesian coordinates are transformed to cylindrical ones and integrated with respect to the circumference coordinate. So, the three-dimensional axisymmetric problems are reduced to systems of one-dimensional singular integral equations requiring t

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15

Bidnichenko, Helen. "LOGARITHMIC SPIRAL AS A GEOMETRIC FORM AND ITS NATURAL AND PRACTICAL APPLICATION." APPLIED GEOMETRY AND ENGINEERING GRAPHICS, no. 108 (July 3, 2025): 3–17. https://doi.org/10.32347/0131-579x.2025.108.3-17.

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This work is devoted to the topical issue of analyzing the geometric features of the logarithmic spiral. Its theoretical and practical aspects and its natural practical application are considered. A mathematical description of the logarithmic spiral is given and its geometric model is developed: the spiral equations are given in polar coordinates and in parametric form, flat geometric models are constructed, and its geometric properties are investigated, which allow the use of this particular form in various technical areas of activity, in particular in mechanical engineering, as well as in as

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16

Feigin, Misha V., and Alexander P. Veselov. "$\vee$ -Systems, Holonomy Lie Algebras, and Logarithmic Vector Fields." International Mathematics Research Notices 2018, no. 7 (2017): 2070–98. http://dx.doi.org/10.1093/imrn/rnw289.

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Abstract It is shown that the description of certain class of representations of the holonomy Lie algebra $\mathfrak g_{\Delta}$ associated with hyperplane arrangement $\Delta$ is essentially equivalent to the classification of $\vee$-systems associated with $\Delta.$ The flat sections of the corresponding $\vee$-connection can be interpreted as vector fields, which are both logarithmic and gradient. We conjecture that the hyperplane arrangement of any $\vee$-system is free in Saito's sense and show this for all known $\vee$-systems and for a special class of $\vee$-systems called harmonic, wh

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17

Wu, Kang, and Yibin Lu. "Numerical computation of preimage domains for spiral slit regions and simulation of flow around bodies." Mathematical Biosciences and Engineering 20, no. 1 (2022): 720–36. http://dx.doi.org/10.3934/mbe.2023033.

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<abstract><p>In this paper, we propose the iterative numerical methods to calculate the conformal preimage domains for the specified logarithmic spiral slit regions and develop the applications of conformal mappings in the simulations of the flow around bodies. Firstly, we postulate that the boundaries of the preimage domains mapped onto logarithmic spiral slits are ellipses. The lengths of the long axes of ellipses and the coordinates of the centers are calculated using our iterative methods. Secondly, each type of the presented iterative method calculates numerical conformal mapp

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18

Feoktistov, Sergey I., and Ivan K. Andrianov. "EQUATIONS OF JOINT LOGARITHMIC DEFORMATIONS IN EULER COORDINATES FOR SOLVING AXISYMMETRIC PRESSURE METAL PROCESSES." Scholarly Notes of Komsomolsk-na-Amure State Technical University, no. 7 (2021): 26–30. http://dx.doi.org/10.17084/20764359-2021-55-26.

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19

Gao, De Cheng, Bin Liu, and Jian Guo Wang. "Texture Classification Research Based on the Logarithmic Polar Coordinates Transform and Support Vector Machine." Applied Mechanics and Materials 39 (November 2010): 226–31. http://dx.doi.org/10.4028/www.scientific.net/amm.39.226.

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In this paper, we have investigated an approach based on log-polar transform and support vector machine (SVM) for texture classification. Firstly, we convert rotation into translation, which reduced the effect of rotation and scale changes using the characteristics of logarithm Polar transformation. Then we extract texture feature after eliminating translation using smooth discrete wavelet transform (SWT) with translation invariant. Finally, support vector machines(SVM) are adopted to the texture classification. The experiment results show the proposed approach can get improved results for tex

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20

Pellegrini, Cláudio C., and Gustavo C. R. Bodstein. "A Modified Logarithmic Law for Neutrally Stratified Flow over Low-Sloped Hills." Journal of Applied Meteorology 44, no. 6 (2005): 900–916. http://dx.doi.org/10.1175/jam2207.1.

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Abstract The study of the atmospheric boundary layer flow over two-dimensional low-sloped hills under a neutral atmosphere finds numerous applications in meteorology and engineering, such as the development of large-scale atmospheric models, the siting of wind turbines, and the estimation of wind loads on transmission towers and antennas. In this paper, the intermediate variable technique is applied to the momentum equations in streamline coordinates to divide the flow into regions, with each characterized by the dominance of different terms. Using a simple mixing-length turbulence closure, a

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21

Koumetio Armel, Azangue, Yiande Deuto Germain, Tene Alain Giresse, and Tchoffo Martin. "The dynamic of quantum entanglement of two dimensional harmonic oscillator in non-commutative space." Physica Scripta 96, no. 12 (2021): 125731. http://dx.doi.org/10.1088/1402-4896/ac42a9.

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Abstract In the present paper, we study the influence of non-commutativity on entanglement in a system of two oscillators-modes in interaction with its environment. The considered system is a two-dimensional harmonic oscillator in non-commuting spatial coordinates coupled to its environment. The dynamics of the covariance matrix, the separability criteria for two Gaussian states in non-commutative space coordinates, and the logarithmic negativity are used to evaluate the quantum entanglement in the system, which is compared to the commutative space coordinates case. The result is applied for t

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22

Liu, Jian Qiao, Zhao Xia Zhai, Guo Hua Jin, Xue Song Liu, and Lin Quan. "Evaluation of Depletion Layer Width in Antimony-Doped Tin Oxide Thin Films for Gas Sensors." Key Engineering Materials 644 (May 2015): 125–28. http://dx.doi.org/10.4028/www.scientific.net/kem.644.125.

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The sensing properties of semiconductive gas sensors originate from the resistance variation of depletion layer in each grain of the element. One of the most fundamental factors in this type of sensors is the width of depletion region. In this work, the antimony-doped tin oxide thin films for gas sensors are prepared via sol-gel routes on alumina substrates. The influence of antimony addition amount on electrical resistance of thin films is concluded. The relationship is plotted in the coordinates of logarithmic resistance against doping amount. On the basis of Schottky barrier model, a novel

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23

Sandulyak, Anna A., Alexander V. Sandulyak, Vera A. Ershova, Darya A. Sandulyak, Nicole Pamme, and Vladimir V. Sleptsov. "On the Influence of Viscosity and Density of a Liquid Medium on Efficiency of Magnetophoresis. Role of Temperature." IOP Conference Series: Earth and Environmental Science 987, no. 1 (2022): 012006. http://dx.doi.org/10.1088/1755-1315/987/1/012006.

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Abstract Significant, but usually insufficiently disclosed and analyzed, parameters of magnetophoresis of magnetoactive particles of liquid-dispersed media are the dynamic viscosity and density of the medium, as well as its temperature, which usually significantly affects the viscosity. The role of viscosity and density is analyzed using the example of such a variant of magnetophoresis as filtration magnetic separation (FMS). This role is reflected in the basic expressions for filtration efficiency and rate limiting. To legalize the role of temperature in these expressions, an approach was use

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24

Xiaojun, Xing, Zuo Xianzhang, and Shen Si. "Subsurface defects recognition using thermography based on second order differential peak method of logarithmic coordinates." Journal of Applied Optics 37, no. 6 (2016): 602–6. http://dx.doi.org/10.5768/jao201637.0603005.

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25

Shcherbakova, K. O. "The problem of high water cut in the products of horizontal wells." Proceedings of higher educational establishments. Geology and Exploration, no. 6 (March 13, 2023): 29–38. http://dx.doi.org/10.32454/0016-7762-2022-64-6-29-38.

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Background. The production of oil and gas by horizontal wells, despite all its advantages, is subject to exploratory and operational complications. At the final stage of their development, such fields become hard-to-recover reserves. Production of oil and gas is often associated with a high water cut, a significant drop in reservoir pressure, and precipitation of asphaltene deposits.Aim. To analyze the problem of early indication of flooding of horizontal wells and do research on existing solutions nowadays.Materials and methods. The dependence of the logarithm of the water-oil ratio on the cu

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26

Ishizuka, M., G. Peng, and Y. Kitamura. "Study on the natural air cooling of electronic equipment casings: Effects of the outlet vent and the power heater locations on the cooling capability." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 216, no. 3 (2002): 269–75. http://dx.doi.org/10.1243/095765002320183586.

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This paper is concerned with the natural cooling of electronic equipment casings. Effects of the size and the location of the outlet vent as well as the relative distance from the outlet vent location to the power heater position on the flow resistance have been investigated experimentally by using a simple model casing simulated for practical natural air cooled electronic equipment casings. The result shows that the mean temperature rise inside the casing increases with increase in the heater input power, but decreases linearly with increase in the vent porosity coefficient in logarithmic coo

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27

Alexandrov, V. A. "An Optimal Choice of Characteristic Polynomial Roots for Pole Placement Control Design." Automation and Remote Control 85, no. 5 (2024): 479–90. http://dx.doi.org/10.31857/s0005117924050038.

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The problem of finding the arrangement of closed-loop control system poles that minimizes an objective function is considered. The system optimality criterion is the value of the H∞ norm of the frequency transfer function relative to the disturbance with constraints imposed on the system pole placement and the values of the H∞ norm of the sensitivity function and the transfer function from measurement noise to control. An optimization problem is formulated as follows: the vector of variables consists of the characteristic polynomial roots of the closed loop system with the admissible values re

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28

Hui (惠得轩), De-Xuan, Zhang-Hu Hu (胡章虎), Wan-Li Shang (尚万里), Xian-Xiu Mei (梅显秀), and You-Nian Wang (王友年). "X-ray beams produced by hot electrons with directional drift velocity in fusion plasmas." Plasma Physics and Controlled Fusion 63, no. 12 (2021): 125029. http://dx.doi.org/10.1088/1361-6587/ac2ea1.

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Abstract Spectra and emission efficiencies of x-rays produced by hot electrons (hot-e’s) with drift Maxwellian distribution are studied using both analytical and numerical methods. The analytic expressions are particularly useful for the analysis of x-ray spectra produced by hot-e’s in laser-produced plasma. Both analytical and numerical results show that when hot-e’s have a nonzero drift velocity, the bremsstrahlung spectrum is still approximately a linear function in logarithmic coordinates, which indicates that the process of inferring hot-e’s temperature from the slope of x-ray spectrum ne

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29

Zhang, Shu Lan, and Nan Qiao Zhang. "Secondary Development of Automatic Drawing Software of Spindle of Numerical Control Lathe." Applied Mechanics and Materials 109 (October 2011): 571–74. http://dx.doi.org/10.4028/www.scientific.net/amm.109.571.

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Looking up data mainly depends on the designer. Automation of looking up related data of charts, curve resource is a key to automatic design of common components, and is neccessory to be solved for strength and structural design automation of common components. A continuous curve on the logarithmic coordinates taken automatically search algorithm and discrete forms of data management and automated check to take the basic data structure to solve all the data graphs and charts automatically check the computer taken. With computer technology, in mechanical product design, various standards curves

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30

Barcelo-Vidal, Carles, and Josep-Antoni Martín-Fernández. "The Mathematics of Compositional Analysis." Austrian Journal of Statistics 45, no. 4 (2016): 57–71. http://dx.doi.org/10.17713/ajs.v45i4.142.

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The term compositional data analysis is historically associated to the approach based on the logratio transformations introduced in the eighties. Two main principles of this methodology are scale invariance and subcompositional coherence. New developments and concepts emerged in the last decade revealed the need to clarify the concepts of compositions, compositional sample space and subcomposition. In this work the mathematics of compositional analysis based on equivalence relation is presented. The two principles are essential attributes of the corresponding quotient space. A logarithmic isom

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31

FRANCIOSA, PAOLO GIULIO, CARLO GAIBISSO, GIORGIO GAMBOSI, and MAURIZIO TALAMO. "A CONVEX HULL ALGORITHM FOR POINTS WITH APPROXIMATELY KNOWN POSITIONS." International Journal of Computational Geometry & Applications 04, no. 02 (1994): 153–63. http://dx.doi.org/10.1142/s0218195994000100.

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We consider the problem of deriving good approximations of the convex hull of a set of points in the plane in the realistic case that only arbitrary finite approximations of the real valued coordinates can be known. In particular, the algorithm we introduce derives sequences of improved certified approximations converging to the exact solution, at the same time allowing the insertion of new points to the problem instance. The complexity analysis of the algorithm is performed by referring to a suitable computation model, based on a RAM with logarithmic costs, and the derived space and time boun

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McGavin, Sharon L., Greg J. Bishop-Hurley, Ed Charmley, Paul L. Greenwood, and Matthew J. Callaghan. "Effect of GPS sample interval and paddock size on estimates of distance travelled by grazing cattle in rangeland, Australia." Rangeland Journal 40, no. 1 (2018): 55. http://dx.doi.org/10.1071/rj17092.

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The distance travelled by an animal, when determined by using global positioning system (GPS) coordinates, is usually calculated assuming linear movement between the recorded coordinates. When using long sample intervals, some movement may be overlooked if linear movement between each recorded position is assumed, because of the tendency of livestock to move in meandering paths. Conversely, overestimation of the true distance travelled could occur with short sample intervals because of the accumulation of extra distance due to GPS measurement error. Data from 10 experiments were used to explor

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Mukherjee, Rudranarayan M., and Kurt S. Anderson. "A Logarithmic Complexity Divide-and-Conquer Algorithm for Multi-flexible Articulated Body Dynamics." Journal of Computational and Nonlinear Dynamics 2, no. 1 (2006): 10–21. http://dx.doi.org/10.1115/1.2389038.

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This paper presents an efficient algorithm for the dynamics simulation and analysis of multi-flexible-body systems. This algorithm formulates and solves the nonlinear equations of motion for mechanical systems with interconnected flexible bodies subject to the limitations of modal superposition, and body substructuring, with arbitrarily large rotations and translations. The large rotations or translations are modelled as rigid body degrees of freedom associated with the interconnecting kinematic joint degrees of freedom. The elastic deformation of the component bodies is modelled through the u

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Mao, Wenjin, and Hongwei Li. "Two three-phase linear power flow models for distribution power system under polar coordinates." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 41, no. 1 (2021): 1–21. http://dx.doi.org/10.1108/compel-10-2019-0425.

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Purpose The purpose of this study is to provide a non-iterative linear method to solve the power flow equations of alternating current (AC) power grid. Traditional iterative power flow calculation is limited in speed and reliability, and it is unsuitable for the real-time and online applications of the modern distribution power system (DPS). Thus, it would be of great significance if a fast and flexible linear power flow (LPF) solution could be introduced particularly necessary for the robust and fast control of DPS, especially when the system consists of star and delta connections ZIP load (a

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Jakobsen, Flemming, Kim Wium Olesen, and Mads Madsen. "A simple method to include vertical resolution in a river model, and results from an implementation." Hydrology Research 36, no. 2 (2005): 163–74. http://dx.doi.org/10.2166/nh.2005.0012.

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A simple method to include vertical resolution in a one-dimensional river model is outlined. The equations on which the method is based are the width-averaged continuity, momentum and transport equations. Some details are given on how to formulate the bed friction in a river model with vertical resolution. The equations are transformed to be in sigma coordinates. The numerical techniques, which make maximum use of an already implemented numerical solution technique in an existing river model, are described. The method is used to implement vertical resolution in the existing river model, MIKE 1

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36

Kotlyar, V. V., A. A. Kovalev, and E. G. Abramochkin. "Asymmetric hypergeometric laser beams." Computer Optics 43, no. 5 (2019): 735–40. http://dx.doi.org/10.18287/2412-6179-2019-43-5-735-740.

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Here we study asymmetric Kummer beams (aK-beams) with their scalar complex amplitude being proportional to the Kummer function (a degenerate hypergeometric function). These beams are an exact solution of the paraxial propagation equation (Schrödinger-type equation) and obtained from the conventional symmetric hypergeometric beams by a complex shift of the transverse coordinates. On propagation, the aK-beams change their intensity weakly and rotate around the optical axis. These beams are an example of vortex laser beams with a fractional orbital angular momentum (OAM), which depends on four pa

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Wang, J., K. Zhan, L. Shien, and L. Yan. "Fundamental characteristics of an approximate correction method for electromagnetic coupling in frequency‐domain induced polarization." GEOPHYSICS 50, no. 2 (1985): 235–41. http://dx.doi.org/10.1190/1.1441913.

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Our studies have determined that both gradient and dipole‐dipole arrays may produce a rather strong electromagnetic (EM) coupling effect under certain conditions. Variations in these apparent effects are closely correlated with changes of surface current density and also influenced by topographic relief. The dipole‐dipole array can provide EM coupling anomalies with the same sign and shape as bona fide induced‐polarization (IP) anomalies. It has been shown by theoretical calculations and model studies that response curves of frequency effects of EM coupling in logarithmic coordinates have dist

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Pozharskii, D. A., and E. D. Pozharskaia. "Contact problems for an inhomogeneous elastic wedge with variable Poisson’s ratio." PNRPU Mechanics Bulletin, no. 1 (December 15, 2021): 63–71. http://dx.doi.org/10.15593/perm.mech/2021.1.07.

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Plane contact problems of the elasticity theory are investigated for a wedge when Poisson’s ratio is an arbitrary smooth function with respect to the angular coordinate while shear modulus is constant. For this case Young’s modulus is also variable with respect to the angular coordinate. A finite contact domain is given on one wedge face, it does not include the wedge apex, while the other wedge face is rigidly fixed (problem A) or stress-free (problem B). To reduce the problems to integral equations with respect to the contact pressure, we use the general Freiberger type representation for th

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Zhu, Zhi Qiang, Wei Xiong, and Shu Sheng Gao. "The Factors of Pseudo Threshold Pressure Gradient." Advanced Materials Research 287-290 (July 2011): 3043–46. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.3043.

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In this paper, we have finished seepage experiments of natural cores from two different areas. And analyzing the data from experiments, we got the curves of permeability and threshold pressure gradients. We found these curves existed good correlation in logarithmic coordinates. We also found that their threshold pressure gradients are different at the same permeability. Seeking the reason why they were different, we checked the experimental process and also tested natural cores form these two areas with the technology of constant speed mercury injection. We discovered that their micro pore str

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Vočadlo, Lidunka, Geoffrey D. Price, and I. G. Wood. "Structures and physical properties of ∊-FeSi-type and CsCl-type RuSi studied by first-principles pseudopotential calculations." Acta Crystallographica Section B Structural Science 56, no. 3 (2000): 369–76. http://dx.doi.org/10.1107/s0108768199016420.

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An investigation of the relative stability of the two known polymorphs of RuSi, having the ∊-FeSi and CsCl structures, has been made by first-principles pseudopotential calculations. The resulting cell volumes and fractional coordinates at P = 0 are in good agreement with experiment. Application of high pressure to the ∊-FeSi phase of RuSi is predicted to produce a structure having almost perfect sevenfold coordination. However, it appears that RuSi having the CsCl-type structure will be the thermodynamically most stable phase for pressures greater than 3.6 GPa. Fitting of the calculated inter

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Bhatnagar, R. M., B. Bhattacharya, and G. Biswas. "Analysis of a pilot valve and taper groove-based compound damping device." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, no. 4 (2008): 859–71. http://dx.doi.org/10.1243/09544062jmes1299.

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This paper describes the lumped mass parameter model of a pilot valve and taper rod-type compounded damping device used for high-speed and high-loading applications such as heavy artillery guns. The modelling of pilot valve and fluid interaction has been described by Euler equations and Laplace equations of potential flow in cylindrical polar coordinates for the axisymmetric situation. The viscosity effects in the model have been accounted through the inclusion of the damping term in the equation of motion of the pilot valve. The model presented has been experimentally validated using a test r

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Zhao, Tian Yu, Hu Yuan Zhang, and Chen Xiang Yu. "Soil-Water Characteristics of Saline Soil in Northwest China." Advanced Materials Research 487 (March 2012): 548–52. http://dx.doi.org/10.4028/www.scientific.net/amr.487.548.

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Geotechnical engineers have become increasingly aware of salt damages caused by water-salt migration.The soil water characteristic curve (SWCC) is a very important tool for determining the engineering properties of unsaturated soil. Using pressure plate extractors, This paper carried out a research on soil-water characteristics of saline soil in northwest China. Then, The relationship between matrix suction and water content was analyzed, the unsaturated hydraulic conductivity in different water content was calculated through predicting model of Van Genuchten(1980). Based on the measurement an

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Berton, R. P. H. "Statistical distributions of water content and sizes for clouds above Europe." Annales Geophysicae 18, no. 3 (2000): 385–97. http://dx.doi.org/10.1007/s00585-000-0385-3.

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Abstract. The statistics of quantities involved in the synthesis of cloud scenes have been investigated from an original data base. Frequency distributions of ice and water content (IWC), horizontal and vertical sizes (L and H), and top temperatures (T) of clouds above Europe have been derived for nine types of clouds (As, Cb, Ci, Cg, LwCg, OrCg, Cs, Ns, Sc). It appears that the cumulated frequency plots can be well fitted with log-normal or Weibull profiles, and that for IWC and T cloud types can be split into two or three classes according to slopes in logarithmic coordinates. Cross-correlat

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Yu, Pei-Zheng, Qian-Wen Jing, and Yan-Qing Hong. "Multi-Level Logarithmic Amplification-Based Fixed Threshold Circular Polarized On-Off Keying Detection for Free-Space Optical Communications." Photonics 10, no. 6 (2023): 667. http://dx.doi.org/10.3390/photonics10060667.

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This study investigates a multi-level logarithmic amplification (MLA)-based fixed threshold circular polarized on-off keying (CP-OOK) detection for free-space optical (FSO) communication links. OOK signal is polarized into a single circular polarization state by a linear polarizer (LP) and a quarter-wave plate (QWP). In the receiver terminal, firstly, circular polarization is transformed into linear polarization utilizing QWP without polarization coordinates alignment between transmitter and receiver. Then, the background noises are decreased by polarization filtering using LP. Then, CP-OOK si

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de Celis, Raul, and Luis Cadarso. "Spot-Centroid Determination Algorithms in Semiactive Laser Photodiodes for Artillery Applications." Journal of Sensors 2019 (January 27, 2019): 1–12. http://dx.doi.org/10.1155/2019/7938415.

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Precision of guided projectiles depends equally on the accuracy in determining the coordinates of the objective and on the exactness of the measurement devices utilized for position and attitude calculation of the projectile. Development of algorithms for low-cost high-precision terminal guidance systems is a cornerstone in research in this field. Semiactive laser (SAL) kits, and particularly quadrant detector devices, have been developed to improve precision in guided weapons. Photodetection system can be functionally divided into two main parts: sensing and processing. The sensed signal is p

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Спесивцев, Виктор Васильевич, та Людмила Евгеньевна Сердюкова. "ВОЗБУЖДЕНИЕ ГАРМОНИЧЕСКИХ ТЕМПЕРАТУРНЫХ ВОЛН В ТВЕРДОМ ОБРАЗЦЕ МАТЕРИАЛА ПРИ КОНВЕКТИВНОМ НАГРЕВЕ". Aerospace technic and technology, № 2 (22 квітня 2019): 36–43. http://dx.doi.org/10.32620/aktt.2019.2.04.

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The article discusses the method and means of exciting harmonic temperature waves in a solid sample material during convective heating, it is typical for the working conditions of heat-stressed assemblies and parts in power plants systems. A supersonic jet of combustion products is used as a heat transfer agent. The scheme of power supply feed and control of the mode of operation of the gas generator is considered, which makes it possible to reliably regulate the modes of its operation and to obtain stable values of the heat transfer agent temperature. For determining the temperature of the he

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Liu, Hao, Rui Bao, and Bin Jun Fei. "Determination of Creep Crack Growth Threshold by Experiments under Elevated Temperature with Pre-Stressed Specimens." Advanced Materials Research 891-892 (March 2014): 371–76. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.371.

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A novel test method is presented in this paper for determination of the creep crack growth threshold. In this method, a wedge is placed in the notch of a standard compact tension (CT) specimen with a pre-crack, which provides an evaluable stress fields characterized with stress intensity factor (K) at the crack tip. Then the specimen is kept in the test temperature for a certain time. The creep crack growth threshold of the material at a given temperature can be obtained by extrapolating the curves of the crack growth rate vs.Kin the double logarithmic coordinates. Since it does not need mecha

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Chen, Bo, Jinbin Zou, and Weiqiang Zhang. "Speckle Noise Removal by Energy Models with New Regularization Setting." Journal of Function Spaces 2020 (July 20, 2020): 1–18. http://dx.doi.org/10.1155/2020/3936975.

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In this paper, we introduce two novel total variation models to deal with speckle noise in ultrasound image in order to retain the fine details more effectively and to improve the speed of energy diffusion during the process. Firstly, two new convex functions are introduced as regularization term in the adaptive total variation model, and then, the diffusion performances of Hypersurface Total Variation (HYPTV) model and Logarithmic Total Variation (LOGTV) model are analyzed mathematically through the physical characteristics of local coordinates. We have shown that the larger positive paramete

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Zhang, Zhihe, Dongkai Zhang, Xiaodong Qiu, Yuanyuan Chen, Sonja Franke-Arnold, and Lixiang Chen. "Experimental investigation of the uncertainty principle for radial degrees of freedom." Photonics Research 10, no. 9 (2022): 2223. http://dx.doi.org/10.1364/prj.443691.

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While the uncertainty principle for linear position and linear momentum, and more recently for angular position and angular momentum, is well established, its radial equivalent has so far eluded researchers. Here we exploit the logarithmic radial position, ln r , and hyperbolic momentum, P H , to formulate a rigorous uncertainty principle for the radial degree of freedom of transverse light modes. We show that the product of their uncertainties is bounded by Planck’s constant, Δ ln r · Δ P H ≥ ℏ / 2 , and identify a set of radial intelligent states that satisfy the equality. We illustrate the

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Zukowski, Pawel, Przemyslaw Rogalski, Tomasz N. Koltunowicz, Konrad Kierczynski, Jan Subocz, and Marek Zenker. "Cellulose Ester Insulation of Power Transformers: Researching the Influence of Moisture on the Phase Shift Angle and Admittance." Energies 13, no. 20 (2020): 5511. http://dx.doi.org/10.3390/en13205511.

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This study investigates the frequency–temperature relations between the phase angle φ and admittance Y for composites of cellulose, synthetic ester, and water nanoparticles. We determined the activation energy value for the relaxation time of a phase shift angle ΔWφ ≈ (0.783 ± 0.0744) eV, which was related to the shift of φ(f) waveforms in higher frequency area with increasing temperature. We found that the position of admittance frequency waveforms in double logarithmic coordinates was simultaneously influenced by the temperature dependence of admittance and its relaxation time. Activation en

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