Journal articles: 'Conical form of breakdow'

1

Moise, Pradeep, and Joseph Mathew. "Bubble and conical forms of vortex breakdown in swirling jets." Journal of Fluid Mechanics 873 (June 24, 2019): 322–57. http://dx.doi.org/10.1017/jfm.2019.401.

Full text

Abstract:

Experimental investigations of laminar swirling jets had revealed a new form of vortex breakdown, named conical vortex breakdown, in addition to the commonly observed bubble form. The present study explores these breakdown states that develop for the Maxworthy profile (a model of swirling jets) at inflow, from streamwise-invariant initial conditions, with direct numerical simulations. For a constant Reynolds number based on jet radius and a centreline velocity of 200, various flow states were observed as the inflow profile’s swirl parameter $S$ (scaled centreline radial derivative of azimuthal velocity) was varied up to 2. At low swirl ($S=1$) a helical mode of azimuthal wavenumber $m=-2$ (co-winding, counter-rotating mode) was observed. A ‘swelling’ appeared at $S=1.38$, and a steady bubble breakdown at $S=1.4$. On further increase to $S=1.5$, a helical, self-excited global mode ($m=+1$, counter-winding and co-rotating) was observed, originating in the bubble’s wake but with little effect on the bubble itself – a bubble vortex breakdown with a spiral tail. Local and global stability analyses revealed this to arise from a linear instability mechanism, distinct from that for the spiral breakdown which has been studied using Grabowski profile (a model of wing-tip vortices). At still higher swirl ($S=1.55$), a pulsating type of bubble breakdown occurred, followed by conical breakdown at 1.6. The latter consists of a large toroidal vortex confined by a radially expanding conical sheet, and a weaker vortex core downstream. For the highest swirls, the sheet was no longer conical, but curved away from the axis as a wide-open breakdown. The applicability of two classical inviscid theories for vortex breakdown – transition to a conjugate state, and the dominance of negative azimuthal vorticity – was assessed for the conical form. As required by the former, the flow transitioned from a supercritical to subcritical state in the vicinity of the stagnation point. The deviations from the predictions of the latter model were considerable.

APA, Harvard, Vancouver, ISO, and other styles

2

Rajamanickam, Kuppuraj, and Saptarshi Basu. "Insights into the dynamics of conical breakdown modes in coaxial swirling flow field." Journal of Fluid Mechanics 853 (August 22, 2018): 72–110. http://dx.doi.org/10.1017/jfm.2018.549.

Full text

Abstract:

The main idea of this paper is to understand the fundamental vortex breakdown mechanisms in the coaxial swirling flow field. In particular, the interaction dynamics of the flow field is meticulously addressed with the help of high fidelity laser diagnostic tools. Time-resolved particle image velocimetry (PIV) (${\sim}1500~\text{frames}~\text{s}^{-1}$) is employed in $y{-}r$ and multiple $r{-}\unicode[STIX]{x1D703}$ planes to precisely delineate the flow dynamics. Experiments are carried out for three sets of co-annular flow Reynolds number $Re_{a}=4896$, 10 545, 17 546. Furthermore, for each $Re_{a}$ condition, the swirl number ‘$S_{G}$’ is varied independently from $0\leqslant S_{G}\leqslant 3$. The global evolution of flow field across various swirl numbers is presented using the time-averaged PIV data. Three distinct forms of vortex breakdown namely, pre-vortex breakdown (PVB), central toroidal recirculation zone (CTRZ; axisymmetric toroidal bubble type breakdown) and sudden conical breakdown are witnessed. Among these, the conical form of vortex breakdown is less explored in the literature. In this paper, much attention is therefore focused on exploring the governing mechanism of conical breakdown. It is should be interesting to note that, unlike other vortex breakdown modes, conical breakdown persists only for a very short band of $S_{G}$. For any small increase/decrease in $S_{G}$ beyond a certain threshold, the flow spontaneously reverts back to the CTRZ state. Energy ranked and frequency-resolved/ranked robust structure identification methods – proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) respectively – are implemented over instantaneous time-resolved PIV data sets to extract the dynamics of the coherent structures associated with each vortex breakdown mode. The dominant structures obtained from POD analysis suggest the dominance of the Kelvin–Helmholtz (KH) instability (axial $+$ azimuthal; accounts for ${\sim}80\,\%$ of total turbulent kinetic energy, TKE) for both PVB and CTRZ while the remaining energy is contributed by shedding modes. On the other hand, shedding modes contribute the majority of the TKE in conical breakdown. The frequency signatures quantified from POD temporal modes and DMD analysis reveal the occurrence of multiple dominant frequencies in the range of ${\sim}10{-}400~\text{Hz}$ with conical breakdown. This phenomenon may be a manifestation of high energy contribution by shedding eddies in the shear layer. Contrarily, with PVB and CTRZ, the dominant frequencies are observed in the range of ${\sim}20{-}40~\text{Hz}$ only. We have provided a detailed exposition of the mechanism through which conical breakdown occurs. In addition, the current work explores the hysteresis (path dependence) phenomena of conical breakdown as functions of the Reynolds and Rossby numbers. It has been observed that the conical mode is not reversible and highly dependent on the initial conditions.

APA, Harvard, Vancouver, ISO, and other styles

3

KALKHORAN, I. M., M. K. SMART, and F. Y. WANG. "Supersonic vortex breakdown during vortex/cylinder interaction." Journal of Fluid Mechanics 369 (August 25, 1998): 351–80. http://dx.doi.org/10.1017/s0022112098001566.

Full text

Abstract:

The head-one interaction of a supersonic streamwise vortex with a circular cylinder reveals a vortex breakdown similar in many ways to that of incompressible vortex breakdown. In particular, the dramatic flow reorganization observed during the interaction resembles the conical vortex breakdown reported by Sarpkaya (1995) at high Reynolds number. In the present study, vortex breakdown is brought about when moderate and strong streamwise vortices encounter the bow shock in front of a circular cylinder at Mach 2.49. The main features of the vortex/cylinder interaction are the formation of a blunt-nosed conical shock with apex far upstream of the undisturbed shock stand-off distance, and a vortex core which responds to passage through the apex of the conical shock by expanding into a turbulent conical flow structure. The geometry of the expanding vortex core as well as the location of the conical shock apex are seen to be strong functions of the incoming vortex strength and the cylinder diameter. A salient feature of the supersonic vortex breakdown is the formation of an entropy-shear layer, which separates an interior subsonic zone containing the burst vortex from the surrounding supersonic flow. In keeping with the well-established characteristics of the low-speed vortex breakdown, a region of reversed flow is observed inside the turbulent subsonic zone. The steady vortex/cylinder interaction flow fields generated in the current study exhibit many characteristics of the unsteady vortex distortion patterns previously observed during normal shock wave/vortex interactions. This similarity of the instantaneous flow structure indicates that the phenomenon previously called vortex distortion by Kalkhoran et al. (1996) is a form of supersonic vortex breakdown.

APA, Harvard, Vancouver, ISO, and other styles

4

Shtern, Vladimir, and Fazle Hussain. "Hysteresis in swirling jets." Journal of Fluid Mechanics 309 (February 25, 1996): 1–44. http://dx.doi.org/10.1017/s0022112096001541.

Full text

Abstract:

This paper explains hysteretic transitions in swirling jets and models external flows of vortex suction devices. Toward this goal, the steady rotationally symmetric motion of a viscous incompressible fluid above an infinite conical stream surface of a half-angle θc is studied. The flows analysed are generalizations of Long's vortex. They correspond to the conically similar solutions of the Navier-Stokes equations and are characterized by circulation Γc given at the surface and axial flow force J1. Asymptotic analysis and numerical calculations show that four (for θc ≤ 90°) or five (for θc > 90°) solutions exist in some range of Γc and J1.The solution branches form hysteresis loops which are related to jump transitions between various flow regimes. Four kinds of jump are found: (i) vortex breakdown which transforms a near-axis jet into a two-cell flow with a reverse flow near the axis and an annular jet fanning out along conical surface θ = θs < θc (ii) vortex consolidation causing a reversal of (i); (iii) jump flow separation from surface θ = θc and (iv) jump attachment of the swirling jet to the surface. As Γc and/or J1 decrease, the hysteresis loops disappear through a cusp catastrophe. The physical reasons for the solution non-uniqueness are revealed and the results are discussed in the context of vortex breakdown theories. Vortex breakdown is viewed as a fold catastrophe. Two new striking effects are found: (i) there is a pressure peak of O(Γ2c) inside the annular swirling jet; and (ii) a consolidated swirling jet forms with a reversed (‘anti-rocket’) flow force.

APA, Harvard, Vancouver, ISO, and other styles

5

Qin, Wei, Ira M. Cohen, and P. S. Ayyaswamy. "Fixed Wand Electronic Flame-Off for Ball Formation in the Wire Bonding Process." Journal of Electronic Packaging 116, no. 3 (September 1, 1994): 212–19. http://dx.doi.org/10.1115/1.2905688.

Full text

Abstract:

In the latest generation of wire bonders, the cycle is so short that the wand electrode is kept stationary and the electronic flame off (EFO) discharge is from the side of the wire. This is the discharge that heats and melts the wire causing roll up into a ball that is pressed down onto the chip to form a ball bond. The balls must be perfectly formed with defects in the few ppm range. In the first part of the paper, the fixed, conically shaped side wand and the improved ring wand design are studied by considering the electrostatic field before the breakdown. In the second part of the paper, discharge development starting from the initial electrostatic field between a wire and a ring wand up to the breakdown, and ionization growth in the gap between the electrodes are both examined by numerical simulations. In the computations, the conservation equations for ions and electrons and Poisson’s equation have been employed for the self-consistent electric field. Based on sensitivity to wire length and wire deflection, the results show that the ring wand is a better design than the conical side wand electrode for ball formation and wire bonding. Also, positive wire polarity is preferred over negative wire polarity.

APA, Harvard, Vancouver, ISO, and other styles

6

Domenicucci, A. "Image Processing Methodology for Determining SI Precipitate Size and Density in Oxide Layers from Conical Dark Field TEM Micrographs." Microscopy and Microanalysis 7, S2 (August 2001): 832–33. http://dx.doi.org/10.1017/s1431927600030233.

Full text

Abstract:

Image processing techniques have been used for decades in many branches of science. with the advent of low cost, highresolution CCD cameras and the advances in personal computing, techniques previously used in other disciplines are increasingly being applied by transmission electron microscopists. The present paper gives an example of using image processing techniques for characterizing the number and size of second phase precipitates in an oxide matrix.Si inclusions in the form of Si precipitates can occur in silicon dioxide films. The inclusions are contained within the films and effectively reduce the local thickness of the oxide. This thinning results in a reduction in the voltage necessary to cause oxide breakdown; the larger is the precipitate, the lower the breakdown voltage. Knowledge of the precipitate size and density is therefore important when assessing the dielectric integrity of these films. The Si precipitates are crystalline and more or less randomly oriented within the matrix.

APA, Harvard, Vancouver, ISO, and other styles

7

Rohlena, Karel, and Martin Mašek. "Ambient fields generated by a laser spark." Nukleonika 61, no. 2 (June 1, 2016): 119–24. http://dx.doi.org/10.1515/nuka-2016-0021.

Full text

Abstract:

Abstract The electric and magnetic fields surrounding a laser spark formed after an optical breakdown due to a focused nanosecond laser beam in a gaseous environment are examined in order to assess their possible influence on the processes going on in the gas medium, mainly chemical reactions triggered by the spark plasma radiation. The magnetic field is generated by the standard mechanism of crossed electron density and temperature gradients, the electric field is supposed to be produced by the plasma polarization due to its radial expansion across the self-generated magnetic field. A simple model of spark plasma formation near the tip of the focal cone is assumed, with a delayed breakdown, which allows the focused laser light to sweep the whole volume of the forming spark right down to the focal caustic and thus to form a centimeter long plasma cone. In this conical geometry, the value of plasma electric dipole moment is evaluated as a measurable quantity as well as approximate values of the electric and magnetic field near the focal caustic, where they both tend to grow in magnitude.

APA, Harvard, Vancouver, ISO, and other styles

8

Posmituha, Olexander, Svyatoslav Kravets, Volodymyr Suponyev, and Kazimir Glavatsky. "Determination of equivalent and optimal sizes of wedge tip from flange for the static perforation of soil." MATEC Web of Conferences 230 (2018): 01011. http://dx.doi.org/10.1051/matecconf/201823001011.

Full text

Abstract:

The purpose of the study is to create a new design of the working tip for the perforation of the soil when laying two or more buildings trenchless way and determine its rational parameters. Method. It is known that for static perforation in the formation of cavities in the soil for communication is traditionally used cone-shaped working elements, which is the most common, cheap and reliable. However, the study revealed inefficiency. The design of the working elements of the soil perforation for trenchless laying of two or more buildings simultaneously in the form of a tip, which consists of a wedge-shaped part and a control part in the form of a rectangle with half-cylinders. The basic principles and mathematical dependences of determining the size of the working body are described. Scientific novelty. Regularities of changes in soil pressure on the lateral, conical and wedge surface, flat and cylindrical part of the tip, allowed to obtain an analytical dependence for the calculation of the resistance force depending on the physical and mechanical properties of the soil, the diameter and the number of cases established simultaneously. Also, when comparing the cone-cylindrical and flat tips, it can be argued that the breakdown force of the flat tip decreases from 1.2 to 1.7 times.

APA, Harvard, Vancouver, ISO, and other styles

9

BILLANT, PAUL, JEAN-MARC CHOMAZ, and PATRICK HUERRE. "Experimental study of vortex breakdown in swirling jets." Journal of Fluid Mechanics 376 (December 10, 1998): 183–219. http://dx.doi.org/10.1017/s0022112098002870.

Full text

Abstract:

The goal of this study is to characterize the various breakdown states taking place in a swirling water jet as the swirl ratio S and Reynolds number Re are varied. A pressure-driven water jet discharges into a large tank, swirl being imparted by means of a motor which sets into rotation a honeycomb within a settling chamber. The experiments are conducted for two distinct jet diameters by varying the swirl ratio S while maintaining the Reynolds number Re fixed in the range 300<Re<1200. Breakdown is observed to occur when S reaches a well defined threshold Sc≈1.3–1.4 which is independent of Re and nozzle diameter used. This critical value is found to be in good agreement with a simple criterion derived in the same spirit as the first stage of Escudier & Keller's (1983) theory. Four distinct forms of vortex breakdown are identified: the well documented bubble state, a new cone configuration in which the vortex takes the form of an open conical sheet, and two associated asymmetric bubble and asymmetric cone states, which are only observed at large Reynolds numbers. The two latter configurations differ from the former by the precession of the stagnation point around the jet axis in a co-rotating direction with respect to the upstream vortex flow. The two flow configurations, bubble or cone, are observed to coexist above the threshold Sc at the same values of the Reynolds number Re and swirl parameter S. The selection of breakdown state is extremely sensitive to small temperature inhomogeneities present in the apparatus. When S reaches Sc, breakdown gradually sets in, a stagnation point appearing in the downstream turbulent region of the flow and slowly moving upstream until it reaches an equilibrium location. In an intermediate range of Reynolds numbers, the breakdown threshold displays hysteresis lying in the ability of the breakdown state to remain stable for S<Sc once it has taken place. Below the onset of breakdown, i.e. when 0<S<Sc, the swirling jet is highly asymmetric and takes the shape of a steady helix. By contrast above breakdown onset, cross-section visualizations indicate that the cone and the bubble are axisymmetric. The cone is observed to undergo slow oscillations induced by secondary recirculating motions that are independent of confinement effects.

APA, Harvard, Vancouver, ISO, and other styles

10

KITA, Naoaki, and HIsao HASEGAWA. "810 Interface Stresses between an Elastic Conical-form Solid and a Rigid Conical-form Hole." Proceedings of The Computational Mechanics Conference 2005.18 (2005): 245–46. http://dx.doi.org/10.1299/jsmecmd.2005.18.245.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

TSUKADA, Tadao, Shu Kui LIU, and Tohru KANADA. "Verification of minimum zone conical taper form." Journal of the Japan Society for Precision Engineering 54, no. 2 (1988): 335–39. http://dx.doi.org/10.2493/jjspe.54.335.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Chen, Y. R., Y. L. Lim, M. H. Wang, and C. Y. Chen. ""Conical Hut": A Basic Form of House Types in Timor Island." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-5/W7 (August 11, 2015): 79–84. http://dx.doi.org/10.5194/isprsarchives-xl-5-w7-79-2015.

Full text

Abstract:

Timor Island situates in the southeast end of Southeast Asia. The island accommodates many ethnic groups, which produce many diverse house types. As visiting East Timor in 2012 and Timor Island in 2014, we found the “Pair- House Type” widely spread over Timor Island. Uma Lulik (holy house), accommodating the ancestry soul, fireplace and elder’s bed, and Uma Tidor (house for sleep), containing living, sleeping and working space, compose the pair-house. The research team visited 14 ethnic groups and their houses, some of which were measured and drawn into 3D models as back to Taiwan. Uma Tidors of each ethnic group are quite similar with rectangular volume and hip roof, however, one of the fourteen ethnic groups can build cylinder houses for Uma Tidor. Uma Luliks of different ethnic groups are diversified and special. One group of the Uma Luliks shows a rectangular or square volume sheltered by a hip roof. The other group of Uma Luliks presents a non-specific volume under a conical roof, that we called the “conical hut”. Seven ethnic groups, Atoni, Weimua, Makassae, Mambai, Bunaq, Kemak and Bekais, have built “conical huts” for the use of Uma Lulik. People of the seven ethnic groups can construct a reasonable structural system to support the conical roof, and take good advantage of the space under the conical roof to meet their sacred needs and everyday life. “Conical Hut” may be regarded as the basic form of the house types adopted by the seven ethnic groups. It contains the basic spatial limits and the formal properties that the construction systems have to follow. Based on the concise rules of the basic form, people of each ethnic group use their talents, skills and building materials to generate variations of “conical hut”, which are different in house scale, spatial layout, construction system and form. The “conical huts” contain the consistency that all the huts come from the basic form, meanwhile, they also present the diversification that each conical hut has differed. “Consistent but diversified”, is one of the most interesting issues in typological study that we can observe in Timorese houses.

APA, Harvard, Vancouver, ISO, and other styles

13

Krotiyuk, L., О. Dubchak, L. Andrieieva, and M. Kornieieva. "Selection on improvement of the sugar beet root form." Agrobìologìâ, no. 2(153) (December 18, 2019): 13–20. http://dx.doi.org/10.33245/2310-9270-2019-153-2-13-20.

Full text

Abstract:

The aim of the study was to create new starting materials of beets with improved oval conical root form, higher weight and sugar content to get high yielding hybrids. Based on the results of the research on root beet form improvement by hybridization of sugar beet root with fodder beet it was proven that the fodder beet can exceed sugar beet on productivity twice under identical agro climatic conditions. To transmit the root-shaped trait, it is not enough to have one crossing with the plants-carriers of the genes controlling the roundness of the form, since the selection of plants in F2 does not exceed 3 % and thus additional cross-breeding is necessary. The estimation of initial forms of beets according to the productivity elements for hybridization is given in the article (the yield of sugar beets recipients samples made 39.7–51.1 t/ha, that of donor of the feed beet variety made 60.5 t/ha). In the hybrid offspring, root crops varied in shape from a spindle-shaped to an oval-conical. Root crops of hybrid specimens of oval and wide-conical shapes were selected, which outweighed the initial forms by productivity: yields – by 3.2–20.8 %, sugar content – by 1.0–3.5 %. Due to the fact that different forms of beets root crops differ in productivity, it is necessary to transfer the form of root crops from fodder beet as more productive to sugar beet. It was noted that sample B11360-68 / Biamara F2 with the highest root mass (780 g) had the highest leaf area of 1.2 m2. The yields made 104.8 % and 103.5 %, respectively by sugar content of the original form. In the second generation we obtained 45.5–59.0 % of root beets with oval and wide-conical shapes and increased by 3.2–20.8 % yield compared to the original forms. The collection of breeding materials of Verkhnyatskiy RSS was supplemented by an oval-conical hybrid specimen and three broad-conical specimens with a smooth root surface that had a less pronounced orthostich and had a high root mass. Key words: sugar beet, fodder beet, productivity, beet root form, crossing, selection.

APA, Harvard, Vancouver, ISO, and other styles

14

Baer, Michael, Alexander M. Mebel, and Robert Englman. "Conical intersection revisited: extension to an elliptic form." Chemical Physics Letters 354, no. 3-4 (March 2002): 243–50. http://dx.doi.org/10.1016/s0009-2614(02)00094-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

TOYODA, Takashi, and Hisao HASEGAWA. "1407 Interface Stresses between a Rigid Conical-form Hole and an Elastic Conical-form Solid Subjected to an Uniform Pressure." Proceedings of the Materials and Mechanics Conference 2010 (2010): 652–53. http://dx.doi.org/10.1299/jsmemm.2010.652.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Ndikilar, Chifu Ebenezer. "Gravitational Fields of Conical Mass Distributions." Journal of Gravity 2013 (April 4, 2013): 1–4. http://dx.doi.org/10.1155/2013/546913.

Full text

Abstract:

The gravitational field of conical mass distributions is formulated using the general theory of relativity. The gravitational metric tensor is constructed and applied to the motion of test particles and photons in this gravitational field. The expression for gravitational time dilation is found to have the same form as that in spherical, oblate spheroidal, and prolate spheroidal gravitational fields and hence confirms an earlier assertion that this gravitational phenomena is invariant in form with various mass distributions. It is shown using the pure radial equation of motion that as a test particle moves closer to the conical mass distribution along the radial direction, its radial speed decreases.

APA, Harvard, Vancouver, ISO, and other styles

17

Keen, K. M., D. Smith, and B. S. Lee. "Improved form of backfire bifilar helix conical beam antenna." Microwave and Optical Technology Letters 14, no. 5 (April 5, 1997): 278–80. http://dx.doi.org/10.1002/(sici)1098-2760(19970405)14:5<278::aid-mop7>3.0.co;2-a.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Tong, Liyong, B. Tabarrok, and Tsun Kuei Wang. "BENDING ANALYSIS OF ORTHOTROPIC CONICAL SHELLS." Transactions of the Canadian Society for Mechanical Engineering 17, no. 2 (June 1993): 215–28. http://dx.doi.org/10.1139/tcsme-1993-0013.

Full text

Abstract:

Using Donnell type shell theory a simple and exact procedure is presented for bending analysis of orthotropic conical shells under various loads. The solution is in the form of a power series in terms of a particularly convenient coordinate system, and its convergence radius is obtained.

APA, Harvard, Vancouver, ISO, and other styles

19

Namikawa, Yoshinori. "A finiteness theorem on symplectic singularities." Compositio Mathematica 152, no. 6 (April 15, 2016): 1225–36. http://dx.doi.org/10.1112/s0010437x16007387.

Full text

Abstract:

An affine symplectic singularity$X$with a good$\mathbf{C}^{\ast }$-action is called a conical symplectic variety. In this paper we prove the following theorem. For fixed positive integers$N$and$d$, there are only a finite number of conical symplectic varieties of dimension$2d$with maximal weights$N$, up to an isomorphism. To prove the main theorem, we first relate a conical symplectic variety with a log Fano Kawamata log terminal (klt) pair, which has a contact structure. By the boundedness result for log Fano klt pairs with fixed Cartier index, we prove that conical symplectic varieties of a fixed dimension and with a fixed maximal weight form a bounded family. Next we prove the rigidity of conical symplectic varieties by using Poisson deformations.

APA, Harvard, Vancouver, ISO, and other styles

20

Pereira, Francisco Estêvão Simão, and Maurício Henrique Costa Dias. "On the Design of Conical Antennas for Broadband Impedance Matching Performance." International Journal of Antennas and Propagation 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/1691580.

Full text

Abstract:

In the scope of broadband radiators, the biconical antenna, or its monopole conical counterpart, is long known to be a proper choice. One common form of such radiator, the spherically capped conical antenna (SCCA), has closed-form solution to its input impedance, from which the broadband performance potential is easily verified. Nonetheless, from the design perspective, apart from a few clues inferred from existing solutions, little is found to accurately guide the choice of the main geometrical parameters of the antenna that will enable it to comply with a set of imposed bandwidth requirements. This paper proposes a simple 10-step sequence to derive conical or biconical antenna design charts. These charts provide straightforward information on the geometrical limits within which the required antenna impedance matching broadband performance is achieved. The method is assessed for the SCCA and the open conical antenna (OCA) using theoretical and simulated estimates of the input impedance. A discussion on the impact of the cap and the feed gap is included.

APA, Harvard, Vancouver, ISO, and other styles

21

TOYODA, Takashi, and Hisao HASEGAWA. "G0301-2-5 Stress Singularity at the Corner of Interface between an Conical-form Elastic Circular Solid Cylinder and Conical-form Rigid Hole." Proceedings of the JSME annual meeting 2009.1 (2009): 29–30. http://dx.doi.org/10.1299/jsmemecjo.2009.1.0_29.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Chen, Meixia, Cong Zhang, Xiangfan Tao, and Naiqi Deng. "Structural and Acoustic Responses of a Submerged Stiffened Conical Shell." Shock and Vibration 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/954253.

Full text

Abstract:

This paper studies the vibrational behavior and far-field sound radiation of a submerged stiffened conical shell at low frequencies. The solution for the dynamic response of the conical shell is presented in the form of a power series. A smeared approach is used to model the ring stiffeners. Fluid loading is taken into account by dividing the conical shell into narrow strips which are considered to be local cylindrical shells. The far-field sound pressure is solved by the Element Radiation Superposition Method. Excitations in two directions are considered to simulate the loading on the surface of the conical shell. These excitations are applied along the generator and normal to the surface of the conical shell. The contributions from the individual circumferential modes on the structural responses of the conical shell are studied. The effects of the external fluid loading and stiffeners are discussed. The results from the analytical models are validated by numerical results from a fully coupled finite element/boundary element model.

APA, Harvard, Vancouver, ISO, and other styles

23

Taras, І. P., and T. O. Pryhorovska. "Study on geometric features of conical threads." Scientific Bulletin of Ivano-Frankivsk National Technical University of Oil and Gas, no. 1(48) (June 29, 2020): 16–22. http://dx.doi.org/10.31471/1993-9965-2020-1(48)-16-22.

Full text

Abstract:

The article studies the problem of oil/gas pipe conical thread reinforcement; in particular, the geometrical fundamentals for tool design for reinforcement. The article considers the main types of conical threads for pipes used in oil/gas industry. It was determined, that to obtain initial data for tools, used to reinforce thread crest and flank, it is necessary to consider conical threads not only as helical lines, but also as helicoid surfaces, to determine what helicoid parameters make the thread conical and obtain relations for the calculation of these geometric parameters. The authors determined geometrical parameters of conical threads and design parameters to develop rollers with deformed protrusions for simultaneous reinforcement of aforementioned thread crests and flank to improve tools for their frictional reinforcement. It was stated, that contrary to cylindrical threads, helicoid’s angles of inclination, which form conical threads, differ not only by the angle of inclination to the plane normal to their axes, but also by the values. The study of conical thread geometrical features refers to a cylindrical one allows to use these features in the design or improvement of tools for its manufacture and/or reinforcement. This approach allows improving the tools for frictional reinforcement of conical locking threads by modifying the lateral deforming elements. It makes possible to simplify tool manufacture, increase tool durability, reinforce the conical thread surface, and improve the quality, performance and economy of the conical thread frictional reinforcement.

APA, Harvard, Vancouver, ISO, and other styles

24

Marian, Marius Gheorghe, Tudor Sajin, and Abdelkrim Azzouz. "Study of Micro Hydropower Plant Operating in Gravitational Vortex Flow Mode." Applied Mechanics and Materials 371 (August 2013): 601–5. http://dx.doi.org/10.4028/www.scientific.net/amm.371.601.

Full text

Abstract:

This paper refers to experimental study of a new type of micro hydropower plant for energy conversion of low river water heads into mechanical work by imposing gravitational vortex flow in spiral form through a vertical conical channel. In this vortex, at different heights of the conical channel, are positioned rotor blades of the turbine with different values of specific speed. The characteristics of the gravitational vortex of water flow through the conical channel, the speed and the power characteristics of the micro hydropower plant were investigated and attempts to efficiency modeling were performed.

APA, Harvard, Vancouver, ISO, and other styles

25

FUKUOKA, Michinari, Tatsuya OHMACHI, and Kenichi MITOME. "Tooth Surface Form of Conical Involute Gears on Faigue Test." Proceedings of the Machine Design and Tribology Division meeting in JSME 2003.3 (2003): 65–66. http://dx.doi.org/10.1299/jsmemdt.2003.3.65.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Lesoon, Courtney. "The Sphero-Conical as Apothecary Vessel: An Argument for Dedicated Use." Muqarnas Online 39, no. 1 (October 7, 2022): 317–31. http://dx.doi.org/10.1163/22118993-00391p13.

Full text

Abstract:

Abstract Sphero-conical vessels are ubiquitous in the archaeological record. However, their intended use has remained a conundrum. A multitude of conjectures have been proposed, such as that the sphero-conical vessel was a container for mercury, a grenade, a perfume sprinkler, an aeolipile, a beer gourd, a hookah pipe, and a plumb bob. Faced with a seemingly contradictory body of evidence, scholars have concluded that the sphero-conical vessel must have been a multi-use object. I disagree. This study offers a theory of dedicated use: the sphero-conical vessel was intended and produced to store pharmaceuticals, specifically apothecary compounds in personal-use dosages. My argument is built on a close analysis of material form, epigraphic evidence, decorative motifs, and representations of the sphero-conical vessel in other media. The re-inscribing of the sphero-conical vessel into a history of medicine as a tool of the robust Islamic pharmacological industry is rich with potential for furthering our understanding of medicine, apothecary, alchemy, apotropaia, and trade in the medieval Mediterranean.

APA, Harvard, Vancouver, ISO, and other styles

27

Dunster, T. M. "Conical functions of purely imaginary order and argument." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 143, no. 5 (September 25, 2013): 929–55. http://dx.doi.org/10.1017/s0308210511001582.

Full text

Abstract:

Associated Legendre functions are studied for the case where the degree is in conical form −½ + iτ (τ real), and the order iμ and argument ix are purely imaginary (μ and x real). Conical functions in this form have applications to Fourier expansions of the eigenfunctions on a closed geodesic. Real-valued numerically satisfactory solutions are introduced which are continuous for all real x. Uniform asymptotic approximations and expansions are then derived for the cases where one or both of μ and τ are large; these results (which involve elementary, Airy, Bessel and parabolic cylinder functions) are uniformly valid for unbounded x.

APA, Harvard, Vancouver, ISO, and other styles

28

Liu, Jinxia, Chao Zhang, Fanchang Zeng, and Wenting Liu. "Influence of Coal Cleats on Conical Pick Cutting Process Based on PFC." Advances in Materials Science and Engineering 2022 (August 24, 2022): 1–11. http://dx.doi.org/10.1155/2022/5607437.

Full text

Abstract:

With the rising mining mechanized level, the conical pick is widely used in mining machines. The structure and mechanical properties of rocks and minerals are important factors affecting the cutting characteristics of the conical pick. In this paper, how the coal cleats affect the cutting process of shearers was researched, which will be of great significance to mining technology design. After analyzing the cutting process of conical pick and the test of coal mechanical properties, a group of coal cutting models of conical pick was established based on the empirical cutting parameters, various cleat spacing, simulation of mechanical performance of coal specimens, profile of conical pick, and SRM (synthetic rock mass) method in PFC (Particle Flow Code). Then, the simulations of the cutting process were carried out. The simulation results show that lump coal chips begin to form and fall off after the conical pick cuts to 50°; the cleats near the conical pick grow to be more obvious fractures; the mean and maximum fluctuations of cutting force increase with the increase of face and butt cleat spacing; the lower the density of cleat is, the more the cracks are formed during the cutting process; the face cleat spacing has greater influence on the service life of conical pick than the butt cleat spacing. This study more vividly reflects the influence of cleats on coal cutting process of the conical pick and plays a guiding role in design of mining technology.

APA, Harvard, Vancouver, ISO, and other styles

29

Sun, Jun, Ke Chen, Kai Qu, Junming Zhao, Tian Jiang, and Yijun Feng. "Controlling Conical Beam Carrying Orbital Angular Momentum with Transmissive Metasurface." International Journal of Antennas and Propagation 2021 (May 29, 2021): 1–10. http://dx.doi.org/10.1155/2021/9951644.

Full text

Abstract:

Conical beams have potential uses in wireless and satellite-based communication. In this study, we propose a method using a transmissive metasurface to achieve full control of the diverging effect of orbital angular momentum (OAM) modes to form the desired conical beam. A patch antenna functioning as the feed source is combined with the transmissive metasurface to enable the integration of the source and metasurface. For full control of conical radiation, including the cone angle and OAM mode, we introduce both radial and circumferential phase gradients to the proposed metasurface. Experiments are conducted in the microwave region to validate the design method, which shows good agreement with the simulation results. The proposed metasurface provides a means of flexibly generating conical beams with the designed OAM mode to assist potential applications in high-speed wireless communication.

APA, Harvard, Vancouver, ISO, and other styles

30

Greenhill, L. M., W. B. Bickford, and H. D. Nelson. "A Conical Beam Finite Element for Rotor Dynamics Analysis." Journal of Vibration and Acoustics 107, no. 4 (October 1, 1985): 421–30. http://dx.doi.org/10.1115/1.3269283.

Full text

Abstract:

The development of finite element formulations for use in rotor dynamics analysis has been the subject of many recent publications. These works have included the effects of rotatory inertia, gyroscopic moments, axial load, internal damping, and shear deformation. However, for most closed-form solutions, the element geometry has been limited to a cylindrical cross-section. This paper extends these previous works by developing a closed-form expression including all of the above effects in a linearly tapered conical cross-section element. Results are also given comparing the formulation to previously published examples, to stepped cylinder representations of conical geometry, and to a general purpose finite element elasticity solution. The elimination of numerical integration in the generation of the element matrices, and the ability of the element to represent both conical and cylindrical geometries, make this formulation particularly suited for use in rotor dynamic analysis computer programs.

APA, Harvard, Vancouver, ISO, and other styles

31

Imbert, J. M., S. L. Winkler, M. J. Worswick, D. A. Oliveira, and S. Golovashchenko. "The Effect of Tool–Sheet Interaction on Damage Evolution in Electromagnetic Forming of Aluminum Alloy Sheet." Journal of Engineering Materials and Technology 127, no. 1 (January 1, 2005): 145–53. http://dx.doi.org/10.1115/1.1839212.

Full text

Abstract:

A study of the effect of tool–sheet interaction on damage evolution in electromagnetic forming is presented. Free form and conical die experiments were carried out on 1 mm AA5754 sheet. Safe strains beyond the conventional forming limit diagram (FLD) were observed in a narrow region in the free form experiments, and over a significant region of the part in the conical die experiments. A parametric numerical study was undertaken, that showed that tool–sheet interaction had a significant effect on damage evolution. Metallographic analysis was carried out to quantify damage in the parts and to confirm the numerical results.

APA, Harvard, Vancouver, ISO, and other styles

32

Kotov, Borys, Serhiy Stepanenko, and Roman Kalinichenko. "Theoretical Study of the Separation of Seed Material According to the Density of Grains by a Conical Vibro-pneumocentrifuge." National Interagency Scientific and Technical Collection of Works. Design, Production and Exploitation of Agricultural Machines, no. 52 (2022): 55–65. http://dx.doi.org/10.32515/2414-3820.2022.52.55-65.

Full text

Abstract:

The article examines the study of the separation of seed material by grain density by a conical vibro-pneumocentrifuge, taking into account the distribution of air velocity in the cross section of the aspiration channel, to determine the rational form and parameters of the working bodies of the conical vibro-pneumocentrifuge, as well as technological indicators of the machine: supply, consumption, efficiency of seed separation into factions. Scientific research has formulated improved mathematical models of grain movement in the vibro-pneumofluidized layer of a conical vibrocentrifuge centrifuge, which take into account the change in the action of the centrifugal force depending on the grain coordinate along the height of the cone, allowing to determine the movement parameters with varying degrees of accuracy. It is substantiated that when using a conical support surface of a vibrocentrifugal centrifuge, the thickness of the mixing layer of grain increases in the direction of movement, and it is possible to determine by theoretical calculations the rational geometric and kinematic parameters of the rotor, which ensure a qualitative separation of the seed material by density. The obtained systems of nonlinear differential equations with initial conditions are solved in the MathCad software environment in the form of grain movement trajectories in the air flow, which allows to calculate and establish the trends of their movement trajectories, which differ by windage coefficients, and to determine the rational values of the parameters of the conical vibropneumocentrifuge.

APA, Harvard, Vancouver, ISO, and other styles

33

Jiang, Hai Bing, Jian Ruan, Hui Min Xu, and Tao Wang. "Mechanical Model’s of Conical Valve’s Spool-Seat Contact Pairs Based on the Hertz Theory." Applied Mechanics and Materials 130-134 (October 2011): 1770–74. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1770.

Full text

Abstract:

Conical valve’s spool-seat contact pairs is consisted of two surfaces of different curvature radius, and form closed circular contact line. It can be considered as the model of elastic hemi-space contact by the Hertz Theory. The numerical simulation and experiment show: The model is suitable for the analysis of conical valve’s spool-seat contact pairs. The conical valve’ sealing performance is very credible and its performance is very good. Maximum stress is smaller than allowable stress of the seat’s material. The consistency of experiment and simulation proves the validity and practicability of the hemi-space contact model of the valve’s spool-seat contact pairs.

APA, Harvard, Vancouver, ISO, and other styles

34

Skachkov, Sergey V., and Sergei V. Shchutsky. "Analysis of the Stresses of the Wall of a Steel Water Tower." Materials Science Forum 931 (September 2018): 352–57. http://dx.doi.org/10.4028/www.scientific.net/msf.931.352.

Full text

Abstract:

We consider the calculation of the wall of a water tower in the form of a welded sheet structure, structurally consisting of a cylindrical vessel with a conical bottom and a roof and a cylindrical support. The creation of the finite element calculation model and determination of the stresses in the tower elements taking into account various features of design, installation and operation of the structure are performed. The questions of local stability of the wall in the joints of cylindrical and conical parts are considered. The necessity of arranging ribs in the conical part along the meridional directions and in the junction points - ring ribs is substantiated.

APA, Harvard, Vancouver, ISO, and other styles

35

Tsukada, T., T. Kanada, and S. Liu. "Method for the evaluation of form errors of conical tapered parts." Precision Engineering 10, no. 1 (January 1988): 8–12. http://dx.doi.org/10.1016/0141-6359(88)90088-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Marinov, Marin, and Petya Asenova. "Teaching the Notion Conic Section with Computer." Mathematics and Informatics LXIV, no. 4 (August 30, 2021): 395–409. http://dx.doi.org/10.53656/math2021-4-5-pred.

Full text

Abstract:

The article discusses the problem of introducing and constructing mathematical concepts using a computer. The Wolfram Mathematica 12 symbolic calculation system is used at each stage of the complex spiral process to form the notion of conic section and the related concepts of focus, directrix and eccentricity. The nature of these notions implies the use of appropriate animations, 3D graphics and symbolic calculations. Our vision of the process of formation of mathematical concepts is presented. The notions ellipse, parabola and hyperbola are defined as the intersection of a conical surface with a plane not containing the vertex of the conical surface. The conical section is represented as a geometric location of points on the plane for which the ratio of the distance to the focus to the distance to the directrix is a constant value. The lines of hyperbola and ellipse are determined by their foci. The equivalence of different definitions for conical sections is commented.

APA, Harvard, Vancouver, ISO, and other styles

37

Zhu, Yongmei, Jiahao Yang, and Hongzhang Pan. "Three-Dimension Crack Propagation Behavior of Conical-Cylindrical Shell." Metals 13, no. 4 (April 3, 2023): 698. http://dx.doi.org/10.3390/met13040698.

Full text

Abstract:

The conical-cylindrical shell is prone to stress concentration in the convex cone position under the action of deep-sea pressures. This results in unidirectional or bidirectional positive tensile stresses on the surfaces of the shell. The conical-cylindrical shell is a large, welded structure. Welding residual stress was generated at the cone-column joint position, resulting in high-stress concentration at this location. Under both the residual stress of welding and seawater pressure, cracks easily form and propagate on the shell weld toe, leading to fatigue damage and even structural failure. In this paper, based on the seawater’s alternating load and the residual stress of welding, the three-dimensional crack propagation process was studied for the submarine conical-cylindrical shell. The effects of crack depth and shape ratio on crack propagation trend and fatigue life were analyzed. The results can provide references for predicting the crack propagation trend, assessing the remaining life and evaluating the structural safety of the submarine conical-cylindrical shell.

APA, Harvard, Vancouver, ISO, and other styles

38

Niu, Yiran, Lin Li, Yanwei Zhang, Shicai Yu, and Jian Zhou. "Micromechanism of the Breakage of Two Spherical Gypsum Particles under Normal–Tangential Contact Conditions." Applied Sciences 11, no. 9 (April 29, 2021): 4039. http://dx.doi.org/10.3390/app11094039.

Full text

Abstract:

Contact breakage of particles makes a large difference in the strength of coarse-grained soils, and exploring the characteristics within the process of the breakage is of great significance. Ignoring the influence of particle shape, the micromechanism of two spherical particles breaking under normal–tangential contact conditions was investigated theoretically and experimentally. Through theoretical analysis, the breakage form, the shape and size of the conical core, and the relationship between the normal and tangential forces at crushing were predicted. Particle contact tests of two gypsum spheres were carried out, in which the breakage forms, features of the conical cores and the normal and tangential forces at crushing were recorded for comparison with the predicted values. The test results and the theoretical predictions showed good agreement. Both the analysis and test demonstrate that the presence of tangential forces causes the conical core to assume the shape of an oblique cone, and the breakage form to change. Moreover, with increasing normal contact force, the tangential force needed for crushing increases gradually first and then decreases suddenly.

APA, Harvard, Vancouver, ISO, and other styles

39

Palchikova, Irina G., Yuliya V. Zhukova, and Evgenii S. Smirnov. "IMAGE-FORMING BY MEANS OF AXICON." Interexpo GEO-Siberia 8 (May 21, 2021): 118–25. http://dx.doi.org/10.33764/2618-981x-2021-8-118-125.

Full text

Abstract:

A theoretical analysis of the image-forming properties of the conical axicon in the scalar diffraction Kirchhoff-Fresnel approximation within the framework of the theory of linear systems revealed that the classical concept of the point spread function is not applicable to axicon images. In the near diffraction zone, a point light source is imaging by a conical axicon in the form of a segment along a straight line connecting the source and the center of the axicon. Moreover, different annular areas of the axicon form different sections on this segment. When used in tandem with a lens, the axicon can allow to increase the depth of focus. Preliminary experimental data have been obtained, which confirm the theoretical conclusions.

APA, Harvard, Vancouver, ISO, and other styles

40

Glover, B. J., M. Perez-Rodriguez, and C. Martin. "Development of several epidermal cell types can be specified by the same MYB-related plant transcription factor." Development 125, no. 17 (September 1, 1998): 3497–508. http://dx.doi.org/10.1242/dev.125.17.3497.

Full text

Abstract:

A MYB-related transcription factor (MIXTA) that controls development of conical cell form is expressed only in the inner epidermis of Antirrhinum petals. Expression of this gene throughout transgenic tobacco plants leads to excess numbers of multicellular trichomes on leaves and floral organs as well as the novel production of conical cells on leaves. These data indicate that conical cells and trichomes are produced by a common developmental pathway. The timing of MIXTA expression suggests that the choice between the cell types depends on the competence for cell division at the time at which the controlling gene is expressed. Duplication of genes and their association with different cis-regulatory regions may therefore result in the specification of novel plant cell types.

APA, Harvard, Vancouver, ISO, and other styles

41

Bloor, M. I. G., and D. B. Ingham. "The flow in industrial cyclones." Journal of Fluid Mechanics 178 (May 1987): 507–19. http://dx.doi.org/10.1017/s0022112087001344.

Full text

Abstract:

A simple mathematical model for the flow in a conical cyclone is developed which allows solutions to be obtained in closed form. The flow in the main body of the cyclone is regarded as inviscid but the nature of the fluid entry to the device and the conical geometry ensure that secondary flows develop which make the flow highly rotational. The results of the theory are compared with data from two quite different experimental investigations, and good agreement is obtained.

APA, Harvard, Vancouver, ISO, and other styles

42

Rangeley, R. W., and M. L. H. Thomas. "Littoral Stratification in Growth form and Fecundity of the Rock Barnacle, Semibalanus Balanoides." Journal of the Marine Biological Association of the United Kingdom 68, no. 4 (November 1988): 591–99. http://dx.doi.org/10.1017/s0025315400028733.

Full text

Abstract:

The population dynamics of rock barnacles, Semibalanus balanoides (L.), residing in low and high intertidal zones are affected by conspicuously different factors. The barnacle population in the high intertidal zone tends to show longterm stability due to a low incidence of both predation and interspecific competition. Wave exposure, desiccation and intraspecific competition are more important factors affecting abundance and size distribution in this zone (Menge, 1976). In the low intertidal zone, barnacle predation by the dogwhelk, Nucella lapillus (L.) is intense (Menge, 1976) and both the adults and larvae are smaller than in the high intertidal zone (Barnes, 1953). The growth form of S. balanoides is density dependent with taller, more columnar individuals predominating at high densities and short conical barnacles at low densities. Lower fecundity of conical individuals may be due to lower internal shell volume compared with columnar forms (Wethey, 1984). Fecundity increases both with increasing age and base length (Arnold, 1977) and is positively density dependent (Wethey, 1984).

APA, Harvard, Vancouver, ISO, and other styles

43

Zhou, Qi. "Magnetic Actuating Alcolock Device with Double Plunger Solenoids." Applied Mechanics and Materials 610 (August 2014): 101–5. http://dx.doi.org/10.4028/www.scientific.net/amm.610.101.

Full text

Abstract:

In order to construct a simply structured alcolock device for autocar steering safety, the plunger solenoid with the conical face pole form is utilized to fabricate a electromagnetic actuating unit with double plunger solenoids. The unit can generate a electromagnetic actuation with long travel to complete the coverage of auto start-up lock hole and hence to stop the vehicle launch; the magnetic actuation is controlled by using a alcohol sensing system, and the shutting function for starting-up lock hole is generated by a baffle installed at the top of plunger solenoids as the actuating control is started up on the basis of an alcohol sensing signal. The plunger solenoid with conical face pole form possesses the output characteristic of long stroke and steady stroke force.

APA, Harvard, Vancouver, ISO, and other styles

44

Zholobov, Aleksandr, and Olga Klyaus. "IMPROVEMENT OF BORING TOOL DESIGN." Transport engineering 2022, no. 10 (October 9, 2022): 19–27. http://dx.doi.org/10.30987/2782-5957-2022-10-19-27.

Full text

Abstract:

The theoretical research objectiveis to create prerequisites for the development of new designs of boring tools. The task to which the paper is devoted: identification of constructive varieties of boring tools; improvement of the geometric shape of the conical part of the tool. Research methods: modeling of elastic deformations of various designs of boring tools. The novelty of the work: a design with a transitional section from the prismatic to the conical part in the form of a cone and a conical part in a barrel-like design is proposed for introduction into metalworking. Research results: optimal geometric shapes and parameters of the boring tool are identified. Conclusions: the paper analyzes the obtained data of theoretical studies and identifies structural changes in the standard boring tools widely used in metalworking.

APA, Harvard, Vancouver, ISO, and other styles

45

Neville, Simon P., Albert Stolow, and Michael S. Schuurman. "Formation of electronic coherences in conical intersection-mediated dynamics." Journal of Physics B: Atomic, Molecular and Optical Physics 55, no. 4 (February 16, 2022): 044004. http://dx.doi.org/10.1088/1361-6455/ac5460.

Full text

Abstract:

Abstract We consider the formation of vibrationally-induced transient electronic coherences driven by conical intersection (CI)-mediated population transfer between two electronic states. By invoking fundamental symmetry arguments, we identify several important factors which modulate the magnitude of these electronic coherences. We consider the sub-cases where the two electronic states have either the same or different Abelian point group symmetry at the Franck–Condon geometry. For the different symmetry case, due to the inherent symmetry of the molecular Hamiltonian, significant electronic coherences are unlikely to form. In contrast, for electronic states of the same symmetry, large magnitude electronic coherences can form. However, the magnitude of these coherences is highly dependent on the topography of the CI. These results offer a guide to experimental studies of electronic coherences which may (or may not) be induced by nuclear motion in the vicinity of a CI, as well as to ab initio simulations which are employed to simulate them.

APA, Harvard, Vancouver, ISO, and other styles

46

Sargolzaie, Naser, Hamid Reza Arab, and Marzieh Mohammadi Moghaddam. "Evaluation of crestal bone resorption around cylindrical and conical implants following 6 months of loading: A randomized clinical trial." European Journal of Dentistry 11, no. 03 (July 2017): 317–22. http://dx.doi.org/10.4103/ejd.ejd_38_17.

Full text

Abstract:

ABSTRACT Objective: The purpose of this clinical study was to evaluate the effect of implant body form (cylindrical and conical implants) on crestal bone levels during 6 months' follow-up after loading. Materials and Methods: A total of 32 SPI implants (19 conical implants/13 cylindrical implants) were randomly placed in 12 male patients using a submerged approach. None of the patients had compromising medical conditions or parafunctional habits. Periapical radiographs using the parallel technique were taken after clinical loading and 6 months later. Clinical indices including pocket depth and bleeding on probing (BOP) were recorded on 6-month follow-up. Data were analyzed by independent samples t-test and Chi-square test with a significance level of 0.05. Results: Six months after loading, crestal bone loss was 0.84 (±0.29) mm around the cylindrical implants and 0.73 (±0.62) mm around the conical types, which was not significantly different (P = 0.54). Pocket depth around the cylindrical and conical implants was 2.61 (±0.45) mm and 2.36 (±0.44) mm, respectively (P = 0.13). BOP was observed among 53.8% and 47.4% of the cylindrical implants and conical (P = 0.13). Bone loss and pocket depth in the maxilla and mandible had no significant difference (P = 0.46 and P = 0.09, respectively). Conclusion: In this study, although bone loss and clinical parameters were slightly higher in the cylindrical implants, there was no significant difference between the conical- and cylindrical-shaped implants.

APA, Harvard, Vancouver, ISO, and other styles

47

Norouzi, Salman, Amir Reza Yaghoubi, Mohammad Bakhshi-Jooybari, and Abdolhamid Gorji. "Experimental Study of Drawing Load Curves in Forming Conical Parts by Hydroforming and Conventional Deep Drawing Processes." Advanced Materials Research 291-294 (July 2011): 556–60. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.556.

Full text

Abstract:

Since conical parts have wide applications in the industry and forming these parts is one of the most complex and difficult fields in sheet metal forming processes, the study on different methods in forming these parts can be useful. Hydroforming and conventional multistage deep drawing are two deep drawing processes which have been used to form conical parts. Hydroforming deep drawing is one of the special deep drawing processes which have been introduced in order to overcome some inherent problems in the conventional deep drawing with rigid tools. In the present work, an experimental program has been carried out to compare the drawing load variation and maximum drawing load in forming pure copper conical-cylindrical cups with the thickness of 2.5 mm by hydroforming and conventional multistage deep drawing processes. The results of the study demonstrate that drawing load variation is more uniform in the forming of conical parts by hydroforming deep drawing process. The maximum drawing load for drawing copper blank occurs at a higher amount in hydroforming process.

APA, Harvard, Vancouver, ISO, and other styles

48

Rao, Pentyala Srinivasa, and Amit Kumar Rahul. "Pressure generation in rough conical bearing using non-Newtonian Rabinowitsch fluid with variable viscosity." Industrial Lubrication and Tribology 71, no. 3 (April 8, 2019): 357–65. http://dx.doi.org/10.1108/ilt-01-2018-0035.

Full text

Abstract:

Purpose This paper aims to investigate the effect of surface roughness (radial and azimuthal) and viscosity variation on a squeeze film of a conical bearing with a non-Newtonian lubricant by using Rabinowitsch fluid model. Design/methodology/approach The main objective is to determine the stochastic nonlinear modified Reynolds equation for rough conical bearing. Later, first-order closed-form solutions are obtained using a small perturbation method and are numerically solved using the Gauss quadrature method. Findings The findings of this paper, numerical calculations, are analyzed for pressure, load carrying capacity and response time. The simulated results indicate that the influence of surface roughness increases the pressure, load carrying capacity and response time, whereas the viscosity variation factor decreases the pressure, load and response time. Originality/value According to both types of surface roughness with viscosity variation, the performance of a squeeze film rough conical bearing was improved by using Rabinowitsch fluid model. As it is inevitable to consider viscosity variation for bearing designer, it leads to a long life period of conical bearing.

APA, Harvard, Vancouver, ISO, and other styles

49

Tanaka, Hiroyuki, and Shunichiro Tanaka. "Growth of Cu-Oxide Protrusion by Ar Ion Irradiation." Materials Science Forum 558-559 (October 2007): 1359–62. http://dx.doi.org/10.4028/www.scientific.net/msf.558-559.1359.

Full text

Abstract:

Cu2O conical micron-scale protrusions have been grown on a preoxidized Cu surface by the Ar ion beam irradiation at 9 kV for 5-20 min in the low vacuum. This Ar ion irradiation is based on the ‘Transcription Method’ which has been originated by B.-S. Xu and S.-I. Tanaka in 1996 to form nanoparticles. Ar ion irradiation induced needle-like nanostructures composed of Cu2O and CuO which were randomly nucleated on Cu surface by the oxidation at 623 K for 10 min in the air. The obtained Cu2O conical protrusions have a controllable length of up to 14.6 μm with diameter in the range of 0.8 μm by changing the Ar ion irradiation angle to the surface. The mechanism of the formation of the conical protrusions is proposed that Cu atoms on the Cu surface activated and sputtered by the Ar ion irradiation diffuse on the surface of needle-like oxide as nuclei along the Ar ion track and react with residual oxygen atoms to grow the conical Cu2O protrusions.

APA, Harvard, Vancouver, ISO, and other styles

50

Pincak, Richard, Alexander Pigazzini, Saeid Jafari, and Cenap Özel. "Discrete Gravity in Emergent Space Theory: Hidden Conical Defects and Teleparallel Gravity." Universe 9, no. 1 (January 1, 2023): 31. http://dx.doi.org/10.3390/universe9010031.

Full text

Abstract:

In the first part of the paper, we try to identify the presence of gravity, at a microscopic level, by introducing conical defects and maintaining an approach that assumes topological equivalence among the underlying manifolds that form the tissue of the D-brane itself. In the second part, we will present an alternative to the conical defects, considering the theory of teleparallel gravity, in which the presence of the torsion and the construction of the brane always occurs within the context of our new interpretation of emergent spaces.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Conical form of breakdow'

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