Journal articles: 'Disk basic'

1

Miranda, Ryan, and Roman R. Rafikov. "Planet–Disk Interaction in Disks with Cooling: Basic Theory." Astrophysical Journal 892, no. 1 (March 30, 2020): 65. http://dx.doi.org/10.3847/1538-4357/ab791a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

FUNATSU, Kazumori, Toshihisa KAJIWARA, Takeshi MINODA, and Yoshinori OHGA. "Basic Study on Disk Type Extruders." Seikei-Kakou 1, no. 1 (1989): 95–103. http://dx.doi.org/10.4325/seikeikakou.1.95.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Kato, Shoji. "Basic Properties of Thin-Disk Oscillations." Publications of the Astronomical Society of Japan 53, no. 1 (February 25, 2001): 1–24. http://dx.doi.org/10.1093/pasj/53.1.1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Mineshige, S. "Accretion Disk Instabilities." International Astronomical Union Colloquium 134 (1993): 83–103. http://dx.doi.org/10.1017/s0252921100013968.

Full text

Abstract:

AbstractBasic properties of accretion disk instabilities are summarized. We first explain the standard disk model by Shakura and Sunyaev. In this model, the dominant sources of viscosity are assumed to be chaotic magnetic fields and turbulence in gas flow, and the magnitude of viscosity is prescribed by so-called a model. It is then possible to build a particular disk model. In the framework of the standard model, accretion disks are stationary, but when some of the basic assumptions are relaxed, various kinds of instabilities appear. In particular, we focus on the thermal limit-cycle instability caused by partial ionization of hydrogen (and helium). We demonstrate that the disk instability model well accounts for the basic observed features of outbursts of dwarf novae and X-ray nova. We then introduce other kinds of instabilities based on the α viscosity model. They are suspected to produce time variabilities observed on a wide range of timescales in close binaries and active galactic nuclei.

APA, Harvard, Vancouver, ISO, and other styles

5

Brodersen, S., D. E. Metzger, and H. J. S. Fernando. "Flows Generated by the Impingement of a Jet on a Rotating Surface: Part I—Basic Flow Patterns." Journal of Fluids Engineering 118, no. 1 (March 1, 1996): 61–67. http://dx.doi.org/10.1115/1.2817514.

Full text

Abstract:

The results of an experimental study of the flow field resulting from the interaction between an impinging jet and a rotating disk are presented. The resulting flow configuration has applications in turbomachinery, for example, to intensify the local heat transfer at turbine disks. The experiments cover separate measurements of the disk-wall flow, the jet flow and interaction between the two. The flow patterns are investigated over a range of jet Reynolds numbers Rejet = 0.66-104 - 6.80-104 (based on jet diameter) and disk Reynolds numbers Redisk 3.4·105 − 6.2· 105 (based on impingement radius), achieved by varying the jet nozzle diameter, jet flow rate, rotational disk speed and the impingement radius. The measurements included the depth of jet penetration into the wall boundary layer, the travel distance of the jet against the direction of disk rotation, and the turbulent and mean velocity distribution. Another objective of this study concerns the type of flow at the impingement region (jet dominated flow or rotation dominated flow) and the conditions for the transition from one to the other. In the first part of the study, the flow structure of the jet and disk flows as well as the three-dimensional flow fields resulting from the interaction are presented.

APA, Harvard, Vancouver, ISO, and other styles

6

Grüner, Martin, and Marion Merklein. "Basic Experimental and Numerical Investigations on Chip Pressing." Key Engineering Materials 554-557 (June 2013): 630–37. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.630.

Full text

Abstract:

Aluminium alloys show a great potential for lightweight constructions due to their high strength and low density but the production of this material is very energy consuming. Also the recycling of aluminium alloys, e.g. chips from the milling process, shows different challenges. Beside contamination by cooling lubricant and oxidation of the surface of the chips the melting and rolling process for new semi finish products needs a high amount of energy. TEKKAYA shows a new approach for recycling of aluminium alloy chips by an extrusion process at elevated temperatures producing different kinds of profiles. A new idea is the production of components directly out of chips using severe plastic deformation for joining of the chips similar to the accumulative roll bonding process in sheet metal forming. In a first approach aluminium alloy chips out of a milling process were uniaxial compressed with different loads inside an axisymmetric tool installed in a universal testing machine. The compressed chip disks subsequently were tested with two experiments to gain information on their stability. First experiment is a disk compression test with the disk standing on its cylindrical surface, giving information on the stability perpendicular to the compression direction. Second experiment is a stacked disk compression test with three disks to investigate the stability parallel to compression direction. During all three tests force and displacement values are recorded by the universal testing machine. These data are also processed to calculate or identify input parameters for the numerical investigations. For numerical simulation ABAQUS in conjunction with the Drucker-Prager-Cap material model, which is often used for sintering processes, seems to be a good choice. By numerical simulation of the experiments and comparison with the experiments input parameters for the material model can be identified showing good accordance. This material model will be used in future numerical investigations of an extrusion process to identify tool geometries leading to high strains inside the material and by this to an increased stability of the parts.

APA, Harvard, Vancouver, ISO, and other styles

7

Marinov, Boycho. "Full Dynamic Reactions in the Basic Shaft Bearings of Big Band Saw Machines." Journal of Theoretical and Applied Mechanics 43, no. 1 (March 1, 2013): 3–18. http://dx.doi.org/10.2478/jtam-2013-0001.

Full text

Abstract:

Abstract The band saws machines are a certain class woodworking machines for longitudinal or transversal cutting as well as for curvilinear wood cutting. These machines saw the wood through a band-saw blade and two feeding wheels. These wheels usually are very large and they are produced with inaccuracies. The centre of mass of the disc is displaced from the axis of rotation of the distance e (eccentricity) and the axis of the disk makes an angle with the axis of rotation. In this paper, the dy- namic reactions in the bearings of the basic shaft, which drives the band saw machines, are analyzed. These reactions are caused by the external loading and the kinematics and the mass characteristics of the rotating disk. The expressions for the full dynamic reactions are obtained. These expressions allow the parameters of the machines to be chosen in such a way that the loading in the shaft and the bearings to be minimal.

APA, Harvard, Vancouver, ISO, and other styles

8

Qian, Wen Xue, Li Yang Xie, and Xiao Wei Yin. "Finite Element Analysis of a Compressor Disk." Advanced Materials Research 118-120 (June 2010): 49–53. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.49.

Full text

Abstract:

Compressor disk is a key rotor part of aeroengines. Alone with the increase of thrust weight ratio of aeroengines, the work conditions of compressor disk are more and more rigor. So the stress level of compressor is very high nowadays. As we know that the stress analysis is a basic of age analysis and reliability analysis, Do a finite element analysis (FEA) is necessary before and after the compressor disks have been made. In this paper, a detail analysis was done with finite element method (FEM), and the stress distribution of disk we got was consistent with the real stress distribution. Also the FEA results show that the location of maximum stress is the failure site of the disk. It is useful work for further work.

APA, Harvard, Vancouver, ISO, and other styles

9

Korakianitis, T., L. Meyer, M. Boruta, and H. E. McCormick. "Alternative Multinutating Disk Engine Configurations for Diverse Applications." Journal of Engineering for Gas Turbines and Power 126, no. 3 (July 1, 2004): 482–88. http://dx.doi.org/10.1115/1.1688770.

Full text

Abstract:

The nutating engine is a new type of internal combustion engine with distinct advantages over conventional piston engines and gas turbines in small power ranges. The engine’s unique arrangement flexibility allows several alternative disk and shaft configurations, each selected for a different application. Variations in cycle temperature ratio and compression ratio during normal operation enable the engine to effectively become a variable-cycle engine, allowing significant flexibility for maximum efficiency or power or other optimizing function for on-ground stationary or for airborne applications. In its basic configuration the core of the engine is a nutating nonrotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk “nutates,” performs a wobbling motion without rotating around its axis. The motion of the disk circumference prescribes a portion of a sphere. A portion of the area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. A companion paper examines the performance potential of the one-disk engine. This paper examines alternative engine configurations. The external combustion chamber enables the engine to operate on a variable compression ratio cycle. In addition, separate disks of unequal size are used for intake and expansion, resulting in distinct and significant power, efficiency, fuel flexibility, and arrangement advantages over conventional piston engines, over gas turbines, and over the basic nutating-engine configuration. The performance of these arrangements is examined for: on-ground power, on-ground efficiency, (auxiliary power, automotive); and for small and light airframe applications for flight Mach numbers from 0 to 1 and altitudes from 0 to 20 km. This publication is the original presentation of the performance potential of several alternative configurations of the basic engine, such as multidisk arrangements, combustion and exhaust disks of different size, and variable-compression ratio (variable cycle) configurations.

APA, Harvard, Vancouver, ISO, and other styles

10

Валиев, Айрат, and Ayrat Valiev. "INVESTIGATION OF SOIL MOTION ALONG THE WORKING SURFACE OF A DISK CULTIVATOR." Vestnik of Kazan State Agrarian University 12, no. 3 (January 11, 2018): 54–60. http://dx.doi.org/10.12737/article_5a1d9587a0d852.23012684.

Full text

Abstract:

The results of theoretical studies of a disk cultivator are presented, the working units of which consist of two flat discs, inclined to each other in the horizontal and vertical planes. The distance between the upper leading edges of the discs is greater than between the lower rear edges. When the discs move in the soil, the layer is jammed between them, breaks off from the bottom of the furrow, rises slightly upwards and is laid back into the furrow in the loosened state. The main constructive and adjusting parameters of the working unit are the inclination angles of discs γ, the distance between the discs d and the radius of the disks R. The purpose of this work is a theoretical study of the soil movement process in the inter-disk space and the rationale for the design and adjusting parameters of the developed disc cultivator. Based on the methods of theoretical mechanics, the terms for separating the soil particles from the main monolith and their motion along the working surface of the disks are investigated. Equations, describing the trajectories of soil particles with allowance for specific soil conditions, characterized by the basic mechanical parameters of the soil and also depending on the parameters of the working organ and the depth of soil cultivation are obtained. Based on the results of solving these equations, it is established that in the process of working at a depth of up to 16 cm, with a distance between the disks d = 0.15 ... 0.20 m, disc angles γ = 6 ... 90 and disk radius R = 0.25 m, the soil will be guaranteed to tear off from the monolith, rise to a height above the horizontal axis of the disk working units and leave the interdisk space. At the same time, on the one hand, the limiting value of the relative deformation of the soil is reached in the layer being processed, its fracture and crumbling are ensured, and on the other hand, the soil particles are thrown forward and the working organs of the disk cultivator are blocked.

APA, Harvard, Vancouver, ISO, and other styles

11

Kudoh, T., and K. Shibata. "Mass Flux and Toroidal Magnetic Field in Magnetically Driven Jets from Accretion Disks: Steady Solutions and Application to Jet/Wind in YSO." International Astronomical Union Colloquium 163 (1997): 751–52. http://dx.doi.org/10.1017/s0252921100043785.

Full text

Abstract:

AbstractWe solved one-dimensional steady and axisymmetric magnetohydrodynamical (MHD) equations to study basic properties of astrophysical jets from accretion disks. We found that the mass flux of the jets depends on the poloidal magnetic field strength of the disk. The mass loss rates observed in T Tauri winds will constrain the physical quantities in the accretion disks.

APA, Harvard, Vancouver, ISO, and other styles

12

Boneva, D. V., E. A. Mikhailov, M. V. Pashentseva, and D. D. Sokoloff. "Magnetic fields in the accretion disks for various inner boundary conditions." Astronomy & Astrophysics 652 (August 2021): A38. http://dx.doi.org/10.1051/0004-6361/202038680.

Full text

Abstract:

Context. The magnetic fields of accretion disks play an important role in studying their evolution. We may assume that its generation is connected to the dynamo mechanism, which is similar with that in the galactic disks. Aims. Here, we propose a model of the magnetic field of the accretion disk that uses the same approaches that have been used for galaxies. It is necessary to obtain the field, which is expected to be less than the equipartition value, and without destroying the disk. To do so, it is necessary to formulate the basic properties of the ionized medium and to estimate the parameters governing the dynamo. Methods. We used the no-z approximation that has been developed for thin disks. We also take different boundary conditions that can change the value of the field significantly. Results. We show that the magnetic field strictly depends on the boundary conditions. Taking zero conditions and the fixed magnetic field condition on the inner boundary, which are connected to the physical properties of the accretion disk, we can avoid solutions that are greater than the equipartition field.

APA, Harvard, Vancouver, ISO, and other styles

13

Watson, William D. "Theory and extragalactic masers." Symposium - International Astronomical Union 206 (2002): 464–78. http://dx.doi.org/10.1017/s0074180900222882.

Full text

Abstract:

Theoretical research on extragalactic masers (and hence this review) is almost entirely directed toward 22 GHz water masers in circumnuclear disks with the focus being the near ideal masing disk at the nucleus of the galaxy NGC4258. The discussion here is organized around (1) the excitation and conditions for the masers, (2) the spatial and spectral appearance of the maser emission, and (3) the mass accretion rate and structure of the disk. In addition, a summary is given of the basic physics (spectral linebreadths and maser polarization) that underlies certain interpretations of these and other astrophysical masers.

APA, Harvard, Vancouver, ISO, and other styles

14

AZUMA, Masayuki, Atsuhiko SHINTANI, and Katsuhisa FUJITA. "405 Basic Study on Sqeal Reduction of a Disk Brake." Proceedings of Conference of Kansai Branch 2007.82 (2007): _4–5_. http://dx.doi.org/10.1299/jsmekansai.2007.82._4-5_.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

IWATA, Hiromu, and Yasuo YOSHIDA. "A Basic Study of Tensioning Effect on Rotating Disk Vibration." Transactions of the Japan Society of Mechanical Engineers Series C 58, no. 547 (1992): 684–89. http://dx.doi.org/10.1299/kikaic.58.684.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Iwata, Hiromu, and Yasuo Yoshida. "Basic Study of Tensioning Effect on Thermally Stressed Disk Vibration." Transactions of the Japan Society of Mechanical Engineers Series C 59, no. 563 (1993): 2015–19. http://dx.doi.org/10.1299/kikaic.59.2015.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Iwata, Hiromu, Yasuo Yoshida, and Koji Hashimoto. "Basic Study of Slit Effect on Thermally Stressed Disk Vibration." Transactions of the Japan Society of Mechanical Engineers Series C 61, no. 584 (1995): 1293–99. http://dx.doi.org/10.1299/kikaic.61.1293.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Glaser, Christian, and Andreas Heuck. "Basic Aspects in MR Imaging of Degenerative Lumbar Disk Disease." Seminars in Musculoskeletal Radiology 18, no. 03 (June 4, 2014): 228–39. http://dx.doi.org/10.1055/s-0034-1375566.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Raducanu, Dorina, Horiana Tudor, and Shigeyoshi Owa. "An extension of a basic univalence criterion." Tamkang Journal of Mathematics 44, no. 4 (December 30, 2013): 417–30. http://dx.doi.org/10.5556/j.tkjm.44.2013.1219.

Full text

Abstract:

Some sufficient conditions for univalence and quasiconformal extension of a class of functions defined by an integral operator are discussed with some examples. This condition involves two arbitrary functions $ g $ and $ h $ analytic in the unit disk. A number of well-known univalent conditions would follow upon specializing the functions and the parameters involved in our main result.

APA, Harvard, Vancouver, ISO, and other styles

20

GAUTHIER, G., P. GONDRET, and M. RABAUD. "Axisymmetric propagating vortices in the flow between a stationary and a rotating disk enclosed by a cylinder." Journal of Fluid Mechanics 386 (May 10, 1999): 105–26. http://dx.doi.org/10.1017/s0022112099004346.

Full text

Abstract:

The destabilization of the stationary basic flow occurring between two disks enclosed by a cylinder is studied experimentally when the radius of the disks is large compared to the spacing. In the explored range of the cell aspect ratio, when one disk only is rotating, circular vortices propagating to the centre are observed above a critical angular velocity. These structures occur naturally but can also be forced by small modulations of the angular velocity of the disk. For each rotation rate the dispersion relation of the instability is experimentally reconstructed from visualizations and it is shown that this dispersion relation can be scaled by the boundary layer thickness measured over the disk at rest. The bifurcation is found to be of supercritical nature. The effect of the forcing amplitude is in favour of a linear convective nature of this instability of the non-parallel inward flow existing above the stationary disk. The most unstable temporal frequency is found to be about four times the frequency of the rotating disk. The evolution of the threshold of this primary instability is described for different aspect ratios of the cell. Finally, two sets of experiments made under transient conditions are presented: one in order to investigate further a possible convective/absolute transition for the instability, and the other to compare with the impulsive spin-down-to-rest experiments of Savas (1983).

APA, Harvard, Vancouver, ISO, and other styles

21

Takeuchi, Yoshinori, and Katsuyuki Tanaka. "Development of Nanometer Flying-Height Slider for Small Magnetic Disk Drives." Journal of Robotics and Mechatronics 17, no. 5 (October 20, 2005): 517–22. http://dx.doi.org/10.20965/jrm.2005.p0517.

Full text

Abstract:

The 90nm and 15nm flying-height sliders we designed for small magnetic disk drives are based on a basic design guide we previously proposed that covers (1) a very small slider, (2) a multipad slider or side-step slider, and (3) a negative-pressure slider use in low spacing mode alone. These experimentally prototyped sliders were confirmed to fly stably on the disk at the prescribed 90nm and 15nm heights, and have been commercialized for 3.5-inch and 2.5-inch hard disk drives. These practical results demonstrate the feasibility of the proposed basic design guide.

APA, Harvard, Vancouver, ISO, and other styles

22

Homola, A. M., C. M. Mate, and G. B. Street. "Overcoats and Lubrication for Thin Film Disks." MRS Bulletin 15, no. 3 (March 1990): 45–52. http://dx.doi.org/10.1557/s0883769400060176.

Full text

Abstract:

Metallic alloy thin film media and ever decreasing head-to-media spacing make severe demands on storage devices. Decreasing head-to-media separation is critical for high storage densities but it also leads to increased slider-disk interactions, which can cause slider and disk wear or even head crashes. Wear can also occur when drives start and stop when the slider contacts the disk at relatively high speeds. The reliability and durability of thin film disks, which provide much higher areal density than conventional oxide disks with particulate media, are achieved by the use of very thin overcoat materials and surface lubricants. This article summarizes the approaches taken in the industry to enhance the tribological performance of magnetic media, with special emphasis on the basic understanding of the processes occurring at the slider-disk interface.The continuous rise in the demand for storage capacity at a competitive price is the prime motivator of the changes we have seen in the data storage industry. It is clearly stimulating the present move away from particulate media, which has long dominated all fields of data storage, i.e., tape, rigid, and flexible disks, to the thin film storage media. Particulate storage devices use magnetic media formulated by dispersing magnetic particles, usually iron oxides, in an organic binder. In thin film storage devices, the storage medium is a continuous magnetic film, usually a cobalt alloy, made either by sputtering or by electroless plating.

APA, Harvard, Vancouver, ISO, and other styles

23

GAUTHIER, G., P. GONDRET, F. MOISY, and M. RABAUD. "Instabilities in the flow between co- and counter-rotating disks." Journal of Fluid Mechanics 473 (December 10, 2002): 1–21. http://dx.doi.org/10.1017/s0022112002002525.

Full text

Abstract:

The flow between two rotating disks (radius to heigh ratio of 20.9), enclosed by a rotating cylinder, is investigated experimentally in the cases of both co- and counter-rotation. This flow gives rise to a large gallery of instability patterns. A regime diagram of these patterns is presented in the (Reb,Ret)-plane, where Reb,t is the Reynolds number associated with each disk. The co-rotation case and the weak counter-rotation case are very similar to the rotor–stator case, both for the basic flow and the instability patterns: the basic flow consists of two boundary layers near each disk and the instability patterns are the axisymmetric vortices and the positive spirals described in the rotor–stator experiments of Gauthier, Gondret & Rabaud (1999), Schouveiler, Le Gal & Chauve (2001), and the numerical study of Serre, Crespo del Arco & Bontoux (2001). The counter-rotation case with higher rotation ratio is more complex: above a given rotation ratio, the recirculation flow becomes organized into a two-cell structure with the appearance of a stagnation circle on the slower disk. A new kind of instability pattern is observed, called negative spirals. Measurements of the main characteristics of this pattern are presented, including growth times, critical modes and phase velocities.

APA, Harvard, Vancouver, ISO, and other styles

24

Freeman, K. C. "The Formation of Disk Galaxies." Symposium - International Astronomical Union 130 (1988): 301–10. http://dx.doi.org/10.1017/s0074180900136186.

Full text

Abstract:

In this talk, I will discuss a few particular topics, rather than attempting a general review of the formation of disk galaxies. First recall the basic structure and kinematics of a disk galaxy like the Milky Way. The Table below lists the four main structural components as they are presently understood, and gives typical masses, and (if known) the characteristic rotational velocities (at the sun) and the radial velocity dispersion for each component. For more details, see Freeman (1987).

APA, Harvard, Vancouver, ISO, and other styles

25

Druchinin, Denis, Petr Popikov, V. Gigko, E. Pozdnyakov, and Sergey Malyukov. "Increasing of the soil basic cultivation quality by forest disk tools." Актуальные направления научных исследований XXI века: теория и практика 3, no. 9 (December 9, 2015): 133–36. http://dx.doi.org/10.12737/16450.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Li, Zhishan, and Yaoyao Shi. "Tool Orientation Optimization for Disk Milling Process Based on Torque Balance Method." Symmetry 12, no. 1 (December 27, 2019): 60. http://dx.doi.org/10.3390/sym12010060.

Full text

Abstract:

Disk milling strategy has been applied in grooving for decades for its capacity to provide huge milling force on difficult-to-cut material. However, basic research on the tool orientation of the disk milling cutter for the disk milling process on the milling free surface, especially on the free surface of the blisk, is still lacking in previous studies. In this study, the minimum residual amount after the disc milling process is used as an optimization target to obtain the optimal tool orientation of the disc cutter. To address the problem mentioned above, a torque balance method, including a torque balance algorithm and concentric circle ray point (CCRP) method is proposed. The torque calculation and torque balance problem are solved by the torque balance algorithm and the problem of generating random points to cause torque symmetry is solved in the CCRP method. Based on the secondary development of UG NX software, a series of tool orientation of disk milling cutter are calculated. Finally, the torque balance method is compared with steepest descent method, Newton method, and conjugate gradient method in the aspects of calculation accuracy, operation speed, and convergence speed. However, both the calculation speed and the convergence speed are better than the other three algorithms. Compared with the other three methods, the operation speed of the torque balance method is reduced by 0.35 times, 1.5 times, and 2.25 times. The results prove the feasibility of the torque balance method in solving the problem of tool orientation optimization of the disk milling cutter.

APA, Harvard, Vancouver, ISO, and other styles

27

Nam, Jae-Hyun, and Jae-Young Kang. "A Basic Experimental Study on the Squeak Noise Using the Pin-on-disk." Transactions of the Korean Society for Noise and Vibration Engineering 22, no. 8 (August 20, 2012): 736–41. http://dx.doi.org/10.5050/ksnve.2012.22.8.736.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Артамонов, Evgenij Artamonov, Котов, Dmitriy Kotov, Артамонова, and Olga Artamonova. "THEORETICAL SUBSTANTIATION OF CONSTRUCTIVE AND REGIME PARAMETERS OF MECHANICAL CELLULAR-DISK SOWING DEVICE FOR SOWING AMARANTH PANICULATE." Bulletin Samara State Agricultural Academy 1, no. 4 (October 27, 2016): 60–66. http://dx.doi.org/10.12737/21793.

Full text

Abstract:

The purpose of the study is improving the uniformity of sowing seeds of amaranth paniculate cellular-disk sowing device. One of the conditions allowing to achieve high planned yield of amaranth is its accurate seeding with specified messagenum interval. Uniform distribution of seeds and plants is necessary due to the high requirements to the area of nutrition. Analysis of the existing agropolicy and designs of modern metering devices for fine-seed crops shows that they do not allow to implement fully agroclavine accuracy of seed distribution in the row when planting amaranth with a variation megamanny intervals (10-15%) and low seeding rate (0.3-0.5 kg/ha), due to the very small sizes of seeds and characteristics of their physical and mechanical properties. In this regard, was developed a constructive-technological scheme of the cellular-disk sowing device, allowing to carry out the sowing amaranth seeds with low seeding rate and high longitudinal uniformity of distribution of seeds in the row. Novelty design cellular-disk sowing device is confirmed by the patents of the Russian Federation for inventions and utility model №61981, №2347349 respectively. The theoretical substantiation of the basic constructive and regime parameters of mechanical cellular-disk sowing device for sowing amaranth, in particular, the analytically determined: unit cell parameters of a seed disc and the velocity of the seed relative to the wire mesh of a seed disc. As a result of theoretical research has been substantiated geometric cell parameters: maximum diameter of the cell Dmax = 1.42 mm, the maximum depth of a cell Nmax = 1.62 mm, and the conditions of collapse of amaranth seeds in a cell, seed disc, namely the critical speed of the seed cattle = to 0.074 m/s and critical frequency of rotation of a seed disc min-1, which will be retraction of the amaranth seeds in a cell of a seed disc.

APA, Harvard, Vancouver, ISO, and other styles

29

Chiba, M., and M. Hanasz. "Basic Properties of Swing-Excitation Mechanism." Symposium - International Astronomical Union 157 (1993): 375–80. http://dx.doi.org/10.1017/s0074180900174455.

Full text

Abstract:

We describe the basic process of coupling between dynamo and density waves in galaxies. The growth rate of magnetic field as a result of coupling is derived, applying the method of multiple time scales to the marginal state of disk dynamo. It is shown that the 1st-order resonance in a perturbation of density and thus the linear swing excitation, is possible. Moreover, the growth rate of magnetic field is always positive and does not depend on the initial phase difference between the magnetic and density waves. Both the numerical and analytical calculations show that ω = 2ω0 (ω: density-wave freq., ω0: dynamo freq.) is still the best condition for resonance due to the linear effect of swing excitation.

APA, Harvard, Vancouver, ISO, and other styles

30

Бартенев, Ivan Bartenev, Донцов, Igor Dontsov, Лысыч, Mikhail Lysych, Шабанов, Mikhail Shabanov, Сенькин, and Ivan Sen'kin. "MODERN WOOD DISKSCARIFIER." Forestry Engineering Journal 7, no. 1 (August 15, 2017): 168–76. http://dx.doi.org/10.12737/25208.

Full text

Abstract:

The article is devoted to problems of forest regeneration and promote natural regeneration in conditions of wood cuttings down, in particular, the designs of tillage tools for primary soil preparation. Tillage equipment operated under such conditions, must possess high permeability and strength, while providing acceptable quality. These requirements correspond to the most ploughs-rippers with disk working bodies. It uses both passive and active working bodies, which brings the first disc plows and heavy harrows, and the second milling tillage. On the basis of the spent constructive analysis of existing tools their classification by drive type (with an active mechanical drive, with an active hydraulic drive, with a passive drive), method of aggregation (rear-mounted mounted, mounted on lateral faces) and to type of the safety mechanism (spring, hydraulic, without safety locks) is resulted.The tools representing various constructive types are in more details considered. Given their technical characteristics: variants of aggregation, type of drive, quantity of working bodies, the width, the diameter of the disk working bodies, depth of processing, type of safety mechanism, weight. The short description of designs and appointment disk rippers is given.On each tool the critical analysis is carried out and conclusions are drawn on possibility of its application in conditions not cleared cuttings down. Based on the analysis formulated the main requirements to prospective disk rippers that will effectively carry out basic preparation of the soil in conditions not cleared cuttings down at height of stubs to 50 sm in various conditions of the Russian Federation.

APA, Harvard, Vancouver, ISO, and other styles

31

SEGU, DAWIT ZENEBE, POLINA V. KHAN, and PYUNG HWANG. "A STUDY OF HEAD–DISK INTERACTION DETECTION IN THE HARD-DISK DRIVES." Surface Review and Letters 22, no. 06 (October 20, 2015): 1550075. http://dx.doi.org/10.1142/s0218625x15500754.

Full text

Abstract:

The reliability and performance of precision mechanical components that experience sliding under contact depend heavily on the friction and wear characteristics at the sliding interface. In order to improve the reliability of the sliding interface, there is a need to predict, measure and monitor any physical interactions at the head–disk interface (HDI). In the present work, the basic tribological characteristics of HDI were analyzed. The HDI during start–stop and constant speed operation using acoustic emission (AE) were studied. The Fast Fourier Transform (FFT) analysis of the AE signal was used to understand the interaction between the AE signal and the state of contact. In addition, we developed laser textured (LT) disk and the contact start–stop (CSS) tests were performed to investigate the effect of dimples on the stiction performance of the HDI. Furthermore, numerical analysis between the slider and disk surface pressure were performed using the boundary coordinate system and divergence formulation for the nonlinear Reynold's equation solution.

APA, Harvard, Vancouver, ISO, and other styles

32

Just, A., B. Fuchs, and R. Wielen. "The Vertical Age Distribution of Stellar Disk Populations in Edge-on Galaxies." Symposium - International Astronomical Union 164 (1995): 423. http://dx.doi.org/10.1017/s0074180900109386.

Full text

Abstract:

The scale height of the disk stars in our Galaxy increases continously with age, which is also seen in the age-velocity dispersion relation of the solar vicinity. In external galaxies a similar evolution of stellar disks can be deduced from the colour distribution of the light in edge-on galaxies. Using physical disk models and stellar population synthesis we compute the luminosity and colour profiles in optical and infrared bands. For diffusion coefficient and SFR constant in time the vertical density profile is exponential. The colour profiles are mainly affected by dust extinction, and the age and metallicity distribution of the stars. The comparison of a basic model with the observed profiles of IC 2531 shows, that these influences can be disentangled by analyzing the systmatic deviations in the colour profiles.

APA, Harvard, Vancouver, ISO, and other styles

33

Liu, Yao, Giovanni Dipierro, Enrico Ragusa, Giuseppe Lodato, Gregory J. Herczeg, Feng Long, Daniel Harsono, et al. "Ring structure in the MWC 480 disk revealed by ALMA." Astronomy & Astrophysics 622 (January 29, 2019): A75. http://dx.doi.org/10.1051/0004-6361/201834157.

Full text

Abstract:

Gap-like structures in protoplanetary disks are likely related to planet formation processes. In this paper, we present and analyze high-resolution (0.17′′× 0.11′′) 1.3 mm ALMA continuum observations of the protoplanetary disk around the Herbig Ae star MWC 480. Our observations show for the first time a gap centered at ~74 au with a width of ~23 au, surrounded by a bright ring centered at ~98 au from the central star. Detailed radiative transfer modeling of the ALMA image and the broadband spectral energy distribution is used to constrain the surface density profile and structural parameters of the disk. If the width of the gap corresponds to 4–8 times the Hill radius of a single forming planet, then the putative planet would have a mass of 0.4–3 MJ. We test this prediction by performing global three-dimensional smoothed particle hydrodynamic gas/dust simulations of disks hosting a migrating and accreting planet. We find that the dust emission across the disk is consistent with the presence of an embedded planet with a mass of ~2.3 MJ at an orbital radius of ~78 au. Given the surface density of the best-fit radiative transfer model, the amount of depleted mass in the gap is higher than the mass of the putative planet, which satisfies the basic condition for the formation of such a planet.

APA, Harvard, Vancouver, ISO, and other styles

34

Sang, Chenglin, Xuecheng Cao, Fangjing Chen, Xuekang Yang, and Yongxian Zhang. "Differential Characterization of Two Kinds of Stem Cells Isolated from Rabbit Nucleus Pulposus and Annulus Fibrosus." Stem Cells International 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/8283257.

Full text

Abstract:

Objective. Nucleus pulposus (NP) and annulus fibrosus (AF) are two main components of intervertebral disc (IVD). We aimed to figure out whether NP and AF also contain stem cells and whether these stem cells share common properties with chondrocytes and/or fibroblasts in their phenotypes or whether they are completely different types of cells with different characteristics.Design. The disk cells were isolated from AF and NP tissues of the same lumbar spine of the rabbits. The properties of these disk cells were characterized by their morphology, population doubling time (PDT), stem cell marker expression, and multidifferentiation potential using tissue culture techniques, immunocytochemistry, and RT-PCR.Results. Both disk cells formed colonies in culture and expressed stem cell markers, nucleostemin, Oct-4, SSEA-4, and Stro-1, at early passages. However, after 5 passages, AFSCs became elongated and NPSCs appeared senescent.Conclusion. This study indicated that IVD contains stem cells and the characteristics of AFSCs and NPSCs are intrinsically different. The findings of this study may provide basic scientific data for understanding the properties of IVD cells and the mechanisms of lower back pain.

APA, Harvard, Vancouver, ISO, and other styles

35

SATO, Toshihisa, Hideshi YOKOTA, and Kenya GOTO. "The Basic Study of Micro-Optics Head for Optical Floppy Disk System." Journal of Advanced Science 4, no. 4 (1992): c24. http://dx.doi.org/10.2978/jsas.4.4_c24.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Wong, B. Y., and D. E. Laughlin. "Determination of basic magnetic unit size in CoCrTa/Cr magnetic disk media." IEEE Transactions on Magnetics 34, no. 1 (1998): 293–98. http://dx.doi.org/10.1109/20.650358.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Ибятов and Ravil Ibyatov. "Approximation of asymmetric flow velocity in inter-disk space of separator." Vestnik of Kazan State Agrarian University 8, no. 4 (January 13, 2014): 61–64. http://dx.doi.org/10.12737/2435.

Full text

Abstract:

We consider the motion of non-Newtonian behavior in the inter-disk space of the liquid separator. The shared medium is supplied from the periphery of the disks and moves to the center of the machine. Under the influence of centrifugal force the particles of the dispersed phase are precipitated to the bottom surface of the top disk to form a thin layer of precipitate, which moves toward the periphery of the disk. The equations of motion are solved by the equal-discharge-increments method. In this case, the flow field is introduced surfaces of equal costs for the continuous phase, which are determined by the conditions of constant flow velocity of the medium between them. To determine the locations of input surfaces, the recurrent type differential equations are recorded. The equations of motion, recorded on the flow lines, are simplified and take the form of ordinary differential equations in the longitudinal coordinate. The term, takes into account the effect of viscous friction in the equation of motion, contains the partial derivatives of the transverse coordinate. For their computation, a grid solution can be represented as a series expansion in the complete system of basis functions, satisfying the boundary condition. The presence of moving sediment layer and the centrifugal force influence causes the asymmetry of the flow in the dispersion medium in the inter-disk space. In this work the basic functions that take into account the asymmetry of the flow were constructed. In order to determine the type of basis functions, the Poiseuille flow in a conical slit with a moving wall was considered. An algebraic equation for calculating the extremum point of the function of speed made up. It is shown, that for the power fluid in the areas of increasing and decreasing functions, there are different solutions. The studies proposed a system of basis functions for the approximation of the grid solutions. It is shown, that the proposed features provide continuity of the viscous stress tensor in the whole flow area.

APA, Harvard, Vancouver, ISO, and other styles

38

Gerbig, Konstantin, Christian T. Lenz, and Hubert Klahr. "Linking planetesimal and dust content in protoplanetary disks via a local toy model." Astronomy & Astrophysics 629 (September 2019): A116. http://dx.doi.org/10.1051/0004-6361/201935278.

Full text

Abstract:

Context. If planetesimal formation is an efficient process, as suggested by several models involving gravitational collapse of pebble clouds, then, not before long, a significant part of the primordial dust mass should be absorbed in many km-sized objects. A good understanding of the total amount of solids in the disk around a young star is crucial for planet formation theory. However, as the mass of particles above the mm size cannot be assessed observationally, one must ask how much mass is hidden in bigger objects. Aims. We performed 0-d local simulations to study how the planetesimal to dust and pebble ratio evolves in time and to develop an understanding of the potentially existing mass in planetesimals for a certain amount of dust and pebbles at a given disk age. Methods. We performed a parameter study based on a model considering dust growth, planetesimal formation, and collisional fragmentation of planetesimals, while neglecting radial transport processes. Results. While at early times, dust is the dominant solid particle species, there is a phase during which planetesimals make up a significant portion of the total mass starting at approximately 104–106 yr. The time of this phase and the maximal total planetesimal mass strongly depend on the distance to the star R, the initial disk mass, and the efficiency of planetesimal formation ɛ. Planetesimal collisions are more significant in more massive disks, leading to lower relative planetesimal fractions compared to less massive disks. After approximately 106 yr, our model predicts planetesimal collisions to dominate, which resupplies small particles. Conclusions. In our model, planetesimals form fast and everywhere in the disk. For a given ɛ, we are able to relate the dust content and mass of a given disk to its planetesimal content, providing us with some helpful basic intuition about mass distribution of solids and its dependence on underlying physical processes.

APA, Harvard, Vancouver, ISO, and other styles

39

Brodersen, S., D. E. Metzger, and H. J. S. Fernando. "Flows Generated by the Impingement of a Jet on a Rotating Surface: Part II—Detailed Flow Structure and Analysis." Journal of Fluids Engineering 118, no. 1 (March 1, 1996): 68–73. http://dx.doi.org/10.1115/1.2817516.

Full text

Abstract:

In Part I of this investigation, the basic flow patterns resulting from the interaction of a turbulent jet and a rotating disk flow were presented paying particular attention to mean and turbulent velocity fields around the jet impingement point on the disk and the flow patterns above the disk in the absence of the jet. The latter was used as a base flow pattern, on which the influence of the jet impingement could be assessed. In Part II, further details of the jet/disk flow interaction problem are discussed in the context of potential turbomachinery cooling applications and previous experimental results.

APA, Harvard, Vancouver, ISO, and other styles

40

Józsa, Gyula I. G. "Warps and Accretion." Proceedings of the International Astronomical Union 6, S277 (December 2010): 71–74. http://dx.doi.org/10.1017/s1743921311022496.

Full text

Abstract:

AbstractWarps are a basic feature of disk galaxies. Usually they occur at radii where the optical disk fades and become most pronounced in the outermost gaseous disks.As such, warps present a massive reservoir to replenish star forming material in the inner, star forming disks. Furthermore, some possible excitation mechanisms for warps connect their formation to the accretion of extragalctic material. Interactions or mergers with gas-rich companions or the direct accretion of the ambient intergalactic medium might lead to the formation of warps, at the same time supplementing fuel to maintain star formation in galactic disks.Employing a number of H i studies of warped galaxies, including ultra-deep observations of the prototype warped galaxies NGC 5907 and NGC 4013, I discuss whether the observed kinematics may show evidence for a connection of warps and accretion from the ambient medium.

APA, Harvard, Vancouver, ISO, and other styles

41

Shu, Ran, Zhigang Chu, and Hongyu Shu. "A Lever-Type Method of Strain Exposure for Disk F-Shaped Torque Sensor Design." Sensors 20, no. 2 (January 19, 2020): 541. http://dx.doi.org/10.3390/s20020541.

Full text

Abstract:

Disk-shaped torque sensors are widely used in robotic joints and wheel driving. However, in terms of conventional spoke-type geometries, there is always a trade-off between sensitivity and stiffness, because their strain exposure depends upon a bending deformation mode which causes strain nonuniformity. This paper presents a lever-type method of strain exposure that performs a uniaxial tension and compression deformation mode to optimize the strain uniformity and improve the trade-off. Moreover, on the basis of this approach, the proposed disk F-shaped torque sensor enjoys has axial thinness, easy installation of strain gauges and flexible customization. The simulation and experimental results have validated the basic design idea.

APA, Harvard, Vancouver, ISO, and other styles

42

Hidayatullah, Muhammad Syarief. "ACUAN TINGGI HILAL PERSPEKTIF NAHDLATUL ULAMA DAN MUHAMMADIYAH." Bilancia: Jurnal Studi Ilmu Syariah dan Hukum 13, no. 2 (December 30, 2019): 275–304. http://dx.doi.org/10.24239/blc.v13i2.496.

Full text

Abstract:

In Indonesia, there are two Islamic community organizations, Nahdlatul Ulama (NU) and Muhammadiyah. Hilal mar'i height reference held by these two organizations is different. In determining hilal mar’i height, NU is based on the disk under the moon, while the Muhammadiyah reference is on the moon's disk. This research becomes more interesting when looking at astronomical theory in general which explains that the moon will remain in the shape of a whole round disk regardless of any phase and when calculating the movement of the moon (altitude, azimuth, elongation, parallax, etc.) which will refer to the midpoint the moon disk. On the other hand, the differences in the reference to the hilal mar’i height perspective NU and Muhammadiyah have not been clearly described, and the basic reasons or theories underlying the use of the hilal hilal height reference. The legal basis used by NU and Muhammadiyah in relation to the hilal height reference refers to the syar'i propositions. However, differences in the definition of the new moon makes the two organizations have different ways of determining the beginning of the month.

APA, Harvard, Vancouver, ISO, and other styles

43

Mathieu, Robert D. "The Short-Period Binary Frequency Among Low-Mass Pre-Main Sequence Stars." International Astronomical Union Colloquium 135 (1992): 30–40. http://dx.doi.org/10.1017/s0252921100006084.

Full text

Abstract:

The pre-main sequence (PMS) binary frequency is a fundamental datum in the study of binary formation. It reflects on numerous basic issues, such as:• The formation process. Binary stars are the primary branch of the star-formation process, and thus their frequency is an essential challenge to star-formation theories. (Indeed, the infrequency of single-star formation is likely as significant as the binary frequency.)• The epoch of binary formation. Assessing whether the binary population exists in total by the pre-main sequence phase sets an upper limit on the binary formation timescale.• Early period evolution. The frequency distribution as a function of period of PMS binaries, when compared to the distribution at the zero-age main sequence, can shed light on early orbital evolution.• The interaction of binaries with disks. The formation and consequent dynamical evolution of a binary with semi-major axis less than typical disk radii must substantially modify disk structures and accretion flows. Thus the binary frequency might differ between PMS stars with and without associated disks.

APA, Harvard, Vancouver, ISO, and other styles

44

Arons, Jonathan. "Accretion onto Magnetized Neutron Stars: Polar Cap Flow and Centrifugally Driven Winds." Symposium - International Astronomical Union 125 (1987): 207–25. http://dx.doi.org/10.1017/s0074180900160784.

Full text

Abstract:

Some basic concepts of accretion onto the polar caps of magnetized neutron stars are reviewed. Preliminary results of new, multidimensional, time–dependent calculations of polar cap flow are outlined, and are used to suggest the possible observability of fluctuations in the X–ray intensity of accretion powered pulsars on time scales of 10–100 msec. The possible relevance of such fluctuations to Quasi–Periodic oscillations is suggested. Basic concepts of the interaction between a disk and the magnetosphere of a neutron star are also discussed. Some recent work on the disk–magnetosphere interaction is outlined, leading to the suggestion that a neutron star can lose angular momentum by driving some or all of the mass in the disk off as a centrifugally driven wind. The relevance of such mass loss to the orbital evolution of the binary is pointed out.

APA, Harvard, Vancouver, ISO, and other styles

45

Greaves, B. L., N. M. G. Borralho, C. A. Raymond, and A. Farrington. "Use of a Pilodyn for the indirect selection of basic density in Eucalyptusnitens." Canadian Journal of Forest Research 26, no. 9 (September 1, 1996): 1643–50. http://dx.doi.org/10.1139/x26-185.

Full text

Abstract:

Six hundred 7-year-old Eucalyptusnitens (Dean & Maid.) trees from 50 open-pollinated families were measured for wood density and Pilodyn penetration across two contrasting sites in eastern Victoria, Australia. Eight Pilodyn observations, two from each of four aspects, were made at a height of 1.3 m. Density was measured on whole disks cut from 1.3 m. Heritability of Pilodyn penetration and disk density at 1.3 m were 0.60 and 0.73, respectively. Phenotypic and genetic correlations between Pilodyn penetration and density at 1.3 m were −0.59 and −0.92, respectively. The high repeatability of Pilodyn penetration (0.90) suggests that only two observations per tree would be required for indirect selection of density. Direct index selection for density gave an expected 13% gain (assuming a selection intensity of 1%), compared with a 11% gain by using indirect Pilodyn selection, a selection efficiency of 84%. However, Pilodyn sampling is faster, cheaper, and not destructive, thus resulting in overall higher expected gains for selection of trees or culling of seedling seed orchards in comparison with the more destructive direct assessment of density.

APA, Harvard, Vancouver, ISO, and other styles

46

Zhdanov, V., E. Fedorova, and M. Khelashvili. "Form of a microlensed line from accretion disk in the linear caustic approximation." Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 57 (2018): 27–31. http://dx.doi.org/10.17721/btsnua.2018.57.27-31.

Full text

Abstract:

The line profiles like that of the fluorescent Fe K or Co K lines in the X-ray spectra of the active galactic nuclei (AGN) reflect characteristics of the central regions of these objects. These lines can be formed in the accretion disks around central supermassive black holes and their shapes are connected with the central black hole spin and the accretion disk inclination angle to the line-of-the-sight. If an AGN is a source of a gravitational lens system with microlensing events, one can get an additional important information about both the accretion disk parameters and gravitational lens parameters as well. Microlensing processes were observed in such gravitational lens systems, as PKS 1830-211, B0218+357, RX J1131-1231 i HE1104-1805, Q2237+0305 and we can suspect to observe there also the spectral appearances of microlensing. Here we performed the numerical simulations of the microlensed relativistic spectral line profiles formed in the AGN accretion disks. Using the inear caustic model we show that the time dependence of the profile is determined essentially by the angle between to the disk axis and the caustic. This gives us an opportunity to assess this orientation. Microlens caustics magnify some parts of the accretion disk more prominently than others. Due to the Doppler effects and differences in the rotation direction this leads to the frequency-dependent magnification which distorts the profile of a relativistic spectral line. Such deformations are variable with time due to relative motions of the source and the microlens, and they can give us possibility to obtain some additional information about the disk brightness profile and caustic orientation relatively to the disk. Here we consider the thin disk model, Schwarzschild black hole, and the linear caustic approximation as well. The numerical simulations of the relativistic emission line profiles distorted by strong gravitational microlensing effect were performed for several different orientations of the linear caustic relatively to the disk, as well as several inclinations of the disk to the line-of-the-sight. Basic presumptions for the numerical modeling were the following: (a) AGN is a source in the gravitational lens system and it its inner parts the luminescent emission lines with relativistic profiles are being emitted; (b) this line is formed in the thin accretion disk quite far away from the central black hole and can be calculated with no taking into account the relativistic effects; (c) the caustic can be considered as a linear one. We show that the relative orientation of the caustic and the disk can be determined from emission lines profiles. Our numerical simulations demonstrate that the difference between profiles corresponding to different caustic orientations appears to be more prominent during the first half of the strong microlensing event, namely, before the crossing the disk center, and this dependence is irrespective to the accretion disk brightness profile. We show that for the spectral accuracy level high enough we have a perspective to determine the caustic orientation from the observational data.

APA, Harvard, Vancouver, ISO, and other styles

47

Liedahl, D. A., and D. F. Torres. "Atomic X-ray spectroscopy of accreting black holes." Canadian Journal of Physics 83, no. 12 (December 1, 2005): 1179–242. http://dx.doi.org/10.1139/p05-062.

Full text

Abstract:

Current astrophysical research suggests that the most persistently luminous objects in the Universe are powered by the flow of matter through accretion disks onto black holes. Accretion disk systems are observed to emit copious radiation across the electromagnetic spectrum, each energy band providing access to rather distinct regimes of physical conditions and geometric scale. X-ray emission probes the innermost regions of the accretion disk, where relativistic effects prevail. While this has been known for decades, it also has been acknowledged that inferring physical conditions in the relativistic regime from the behavior of the X-ray continuum is problematic and not satisfactorily constraining. With the discovery in the 1990s of iron X-ray lines bearing signatures of relativistic distortion came the hope that such emission would more firmly constrain models of disk accretion near black holes, as well as provide observational criteria by which to test general relativity in the strong field limit. Here, we provide an introduction to this phenomenon. While the presentation is intended to be primarily tutorial in nature, we aim also to acquaint the reader with trends in current research. To achieve these ends, we present the basic applications of general relativity that pertain to X-ray spectroscopic observations of black hole accretion-disk systems, focusing on the Schwarzschild and Kerr solutions to the Einstein field equations. To this, we add treatments of the fundamental concepts associated with the theoretical and modeling aspects of accretion disks, as well as relevant topics from observational and theoretical X-ray spectroscopy.PACS Nos.: 32.30.Rj, 32.80.Hd, 95.30.Dr, 95.30.Sf, 95.85.Nv, 97.10.Gz. 97.80.Jp, 98.35.Mp, 98.62.Mw

APA, Harvard, Vancouver, ISO, and other styles

48

Sudar, D., H. Božić, and D. Ruždjak. "Applying the Steepest Descent Method with BINSYN on RY Per Photometry." Proceedings of the International Astronomical Union 7, S282 (July 2011): 323–24. http://dx.doi.org/10.1017/s1743921311027724.

Full text

Abstract:

AbstractRecent studies of the Algol-type binary RY Per presented strong evidence that there is an accretion disk around the primary in the system. We used new UBV photometry from Hvar Observatory and the BINSYN software package in order to determine the basic parameters of the disk. The search for the best parameter set was performed with a fully automated steepest descent method. The resulting disk is large and visible at all orbital phases. Somewhat surprising is the large mass transfer rate which should be tied with, currently unreported, secular period changes.

APA, Harvard, Vancouver, ISO, and other styles

49

Baade, D. "Observed Periodic Phenomena." International Astronomical Union Colloquium 175 (2000): 178–91. http://dx.doi.org/10.1017/s0252921100055809.

Full text

Abstract:

AbstractThe wide range of periodic and cyclic variabilities commonly observed in Be stars and their circumstellar disks is reviewed. Many of them are related to the basic nonradial pulsation, the effects of which may range from the photosphere to the disk. Through pulsation-triggered outbursts, some stars may owe their Be characteristics largely to their intrinsic variability. However, because late-type Be stars do not normally show detectable short-periodic variability, this is probably not true of all Be stars. Comparisons are made with other variable early-type stars.

APA, Harvard, Vancouver, ISO, and other styles

50

YOSHIZAWA, Koji, and Tsutomu EZUMI. "252 A Basic Study on Opening Space of Reverse Buckling Type Rapture Disk." Proceedings of Yamanashi District Conference 2009 (2009): 52–53. http://dx.doi.org/10.1299/jsmeyamanashi.2009.52.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Disk basic'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles