Academic literature on the topic 'Symmetrically separated set'
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Journal articles on the topic "Symmetrically separated set"
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Biswas, Ranita, Sebastiano Cultrera di Montesano, Herbert Edelsbrunner, and Morteza Saghafian. "Continuous and Discrete Radius Functions on Voronoi Tessellations and Delaunay Mosaics." Discrete & Computational Geometry 67, no. 3 (February 7, 2022): 811–42. http://dx.doi.org/10.1007/s00454-022-00371-2.
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AbstractThe Voronoi tessellation in $${{{\mathbb {R}}}}^d$$ R d is defined by locally minimizing the power distance to given weighted points. Symmetrically, the Delaunay mosaic can be defined by locally maximizing the negative power distance to other such points. We prove that the average of the two piecewise quadratic functions is piecewise linear, and that all three functions have the same critical points and values. Discretizing the two piecewise quadratic functions, we get the alpha shapes as sublevel sets of the discrete function on the Delaunay mosaic, and analogous shapes as superlevel sets of the discrete function on the Voronoi tessellation. For the same non-critical value, the corresponding shapes are disjoint, separated by a narrow channel that contains no critical points but the entire level set of the piecewise linear function.
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Abo-elenein, Mohamed Hemdan, Salah Eldeen Ibrahim Hassab Elnaby, Amin Fahim Hassan, and Afaf Mahmoud Abd-Rabou. "Modeling for Generating Femtosecond Pulses in an Er-Doped Fiber Using Externally Controlled Spectral Broadening and Compression Mechanisms." Photonics 9, no. 4 (March 22, 2022): 205. http://dx.doi.org/10.3390/photonics9040205.
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A model for generating femtosecond laser pulses from a low-power mode-locked laser of moderate temporal half-width was proposed. This was achieved by injecting the pulse into a single-mode inverted-populated Er-doped fiber where self-focusing and absorption were avoided. To initiate spectral broadening, the pulse was phase-modulated by subjecting a part of the fiber to an electric field of suitable intensity and frequency generated into a circular capacitor. To stimulate temporal compression, the phase-modulated pulse was introduced into a combination of two prism sets located symmetrically with respect to the x-axis. After passing the pulse through the first prism set, its spectral components were spatially separated in the y-axis. The spectral phases were manipulated by redirecting the spectral components through a slab cross-section that was subjected to a spatially modulated DC electric field. After passing the slab, the pulse is directed into the second prism set, where the spectral components were spatially overlapped and propagated outside the compressor with the same slope and dimension as before entering the compressor. Constructive super positioning of the phase-manipulated spectral components gave maximum intensity only at a specified location.
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Becker, J., K. Rademann, and F. Hensel. "Electronic and Geometrical Structure of Se5, Se6, Se7, and Se8." Zeitschrift für Naturforschung A 46, no. 5 (May 1, 1991): 453–61. http://dx.doi.org/10.1515/zna-1991-0513.
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AbstractThe vacuum-UV-photoelectron spectra of Se2, Se5, Se6, Se7, and Se8 have been recorded at a photon energy of h ν= 10.0 eV. The isolated molecules are examined in a supersonic molecular beam employing a new photoelectron-photoion coincidence technique. The structure of the photoelectron spectra of selenium molecules with even and odd numbers of atoms differs in a characteristic manner. While the spectra of Se6 and Se8 show one single broad band, three separated bands with different intensities are observed for Se5 and two for Se7. The spectra are compared to molecular orbital energy calculations based on theoretically supposed geometries. The comparison indicates that Se6 and Se8 have Dnd-symmetrical ring structures, whereas Se5 and Se7 are C1h-symmetrical rings
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Kock, Guillaume, Philippe Combette, Marwan Tedjini, Markus Schneider, Caroline Gauthier-Blum, and Alain Giani. "Experimental and Numerical Study of a Thermal Expansion Gyroscope for Different Gases." Sensors 19, no. 2 (January 17, 2019): 360. http://dx.doi.org/10.3390/s19020360.
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A new single-axis gas thermal gyroscope without proof mass is presented in this paper. The device was designed, manufactured and experimentally characterized. The obtained results were compared to numerical simulation. The working principle of the gyroscope is based on the deflection of a laminar gas flow caused by the Coriolis effect. A bidirectional hot air flow is generated by alternating activation of two suspended resistive micro-heaters. The heated gas is encapsulated in a semi-open cavity and the gas expands primarily inside the cavity. The thermal expansion gyroscope has a simple structure. Indeed, the device is composed of a micromachined cavity on which three bridges are suspended. The central bridge is electrically separated into two segments enabling to set up two heaters which may be supplied independently from each other. The two other bridges, placed symmetrically on each side of the central bridge, are equipped with temperature detectors which measure variations in gas temperature. The differential temperature depends on the rotational velocity applied to the system. Various parameters such as the heating duty cycle, the type of the gas and the power injected into the heaters have been studied to define the optimal working conditions required to obtain the highest level of sensitivity over a measurement range of around 1000°/s. The robustness of the device has also been tested and validated for a shock resistance of 10,000 g for a duration of 400 µs.
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Moore, D. W., and D. I. Pullin. "Inviscid separated flow over a non-slender delta wing." Journal of Fluid Mechanics 305 (December 25, 1995): 307–45. http://dx.doi.org/10.1017/s0022112095004642.
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We consider inviscid incompressible flow about an infinite non-slender flat delta wing with leading-edge separation modeled by symmetrical conical vortex sheets. A similarity solution for the three dimensional steady velocity potential Φ is sought with boundary conditions to be satisfied on the line which is the intersection of the wing sheet surface with the surface of the unit sphere. A numerical approach is developed based on the construction of a special boundary element or ‘winglet’ which is effectively a Green function for the projection of ∇2Φ = 0 onto the spherical surface under the similarity ansatz. When the wing semi-apex angle γo is fixed satisfaction of the boundary conditions of zero normal velocity on the wing and zero normal velocity and pressure continuity across the vortex sheet then leads to a nonlinear eigenvalue problem. A method of ensuring a condition of zero lateral force on a lumped model of the inner part of the rolled-up vortex sheet gives a closed set of a equations which is solved numerically by Newton's method. We present and discuss the properties of solutions for γ0 in the range 1.30 < γ <89.50. The dependencies of these solutions on γ0 differs qualitatively from predictions of slender-body theory. In particular the velocity field is in general not conical and the similarity exponent must be calculated as part of the global eigenvalue problem. This exponent, together with the detailed flow field including the position and structure of the separated vortx sheet, depend only on γ0. In the limit of small γ0, a comparison with slender-body theory is made on the basis of an effective angle of incidence.
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HARDMAN, J. R., and P. E. HANCOCK. "Moderately three-dimensional separated and reattaching turbulent flow." Journal of Fluid Mechanics 649 (April 13, 2010): 341–70. http://dx.doi.org/10.1017/s0022112009993478.
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A fully three-dimensional turbulent separated flow was set up such that it had a systematic link to two-dimensional flow, as a way of investigating the more complicated nature of this flow type. The central region of the flow was fully three-dimensional, but was bounded on its sides by regions of ‘spanwise invariance’ in which the flow was invariant in the lateral direction, or very nearly so. A special case of spanwise invariance, which is statistically two-dimensional, is one in which the streamlines are also coplanar, or at least nominally so in numerous experimental studies. Another aspect of the present arrangement is that the side regions should ideally provide well-defined boundary conditions. The separation was formed downstream of a doubly swept normal flat plate, forming a ‘v’-shaped separation line, mounted on the front of a splitter plate, mounted in the centre of the wind tunnel working section. The predominantly inward flow to the central region implies a negative lateral strain rate (∂W/∂z), but all nine strain rates are non-zero. Measurements were made using pulsed-wire anemometry techniques for mean velocities, Reynolds stresses and wall shear stress. Even though the sweep angle is mild at ±10°, the effect is to increase the bubble height by over 50% in its centre to create a ‘bulge’, symmetrical about the centreline. The degree of three-dimensionality is described as moderate in that the peak inflow velocity from the side regions is less than 0.2 of the free-stream velocity, but comparable with the peak in the reverse-flow velocity. A larger sweep angle would give a larger inflow velocity. A separate study (Cao & Hancock, Eur. J. Mech. B/Fluids, vol. 23, 2004, p. 519) has shown that the bulge persists very far downstream, so that accurate physical modelling of the separated region is likely to be important in modelling the flow well downstream. An intermediate region exists between the invariant side region and the bulge, where all the stress levels are reduced, as would be expected from the effects of streamline convergence. Although overall there is a flow inward to the centre (streamline convergence), part of the overlying shear layer is subjected to diverging flow and an intensification of Reynolds stresses near the centre of the bulge.
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Savina, Lyudmila, Valeriy Savin, and Valentin Osadchy. "The rolls calibration development and caliber drawings preparation with the computer software for the bent profiles production and straight-through pipes formation for laser welding." MATEC Web of Conferences 224 (2018): 04029. http://dx.doi.org/10.1051/matecconf/201822404029.
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A computer program has been created for selecting the profiling route, calculating the rolls for the manufacture of bent symmetrical and asymmetric profiles of virtually any real configurations with the issuance of a complete set of drawings. The algorithm of the program is based on the mathematical model of the strip profiling process, which allows geometric and energy-strength parameters calculation. To create an algorithm for designing roll calibrations to produce curved profiles, a unified description of the shape of the profile was proposed. The left and right halves of the cross section of the profile are treated as separate sets of alternating straight sections and rounds. The configuration of each of them for one and the other profile half is entered separately, starting from the middle. For each point of conjugation (the beginning and end of the section), the coordinates, the rounding radius and the rotation angle are specified (or calculated in the future). The accepted profile shape description makes it possible to compile a general algorithm for calculating the roll calibrations of virtually any profiles, and not to develop an algorithm for each profile or group of profiles.
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Islam, Shahnoor, Sadruddin Al Masud, Nazmul Haider Chawdhary, M. Mozaffar Hossain, SM Shafiqul Alam, M. Abul Kalam, Asit Chandra Sarkar, et al. "Successful Separation of Conjoined Twins: Experience of a Tertiary Care Hospital." Bangladesh Journal of Child Health 42, no. 2 (July 31, 2018): 73–78. http://dx.doi.org/10.3329/bjch.v42i2.37762.
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Background: The separation of conjoined twins presents a unique challenge to many pediatric surgical specialties. Meticulous preoperative investigations, planning and multidisciplinary team approach led by pediatric surgeon contribute to the success of surgical separation. The aim of this study is to share our experiences of one hospital to enhance skill for treating conjoined twins regarding anatomic variations, investigations, surgical aspects, outcomes and rehabilitation.Methodology: All cases of symmetrical conjoined twins who were treated from July 2009 to February 2018 at the Pediatric Surgery Department of Dhaka Medical College Hospital, Dhaka, Bangladesh were included in this prospective type of study. All types of parasitic twins were excluded. Prenatal ultrasound diagnosis, gender, birth weight, anatomy of the twins, the age and weight at the time of the separation surgery, the length of surgery, the duration of anesthesia during the separation surgery, a detailed description of the separation surgery, the type of skin closure, postoperative complications and death were studied.Results: There were three sets of thoraco-omphalo-ischiopagus twins, one set of thoraco-omphalopagus twins, one set of pygopagus twins. Three sets had no prenatal visit or ultrasound evaluation. Two sets of conjoined twins were failed to separate due to the complexity of the organs that were shared by both twins and instability leading to death. Only one set of pygopagus twins was successfully separated. Emergency colostomies were done on pygopagus twins due to the presence of anorectal anomalies. The surgical survival rate was 100%. One set of twins who did not undergo separation due to refusal of treatment was currently alive. One set of twins was under evaluation and currently alive.Conclusion: The overall success of conjoined twin separation depends on the experience and preparedness of treating team led by pediatric surgeon and resources available at the hospital. No single discipline can expect to have all the necessary talents.Bangladesh J Child Health 2018; VOL 42 (2) :73-78
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Goja, Bojan. "Giovanni Vendramin i iluminacije u inkunabulama samostana Sv. Frane u Šibeniku." Ars Adriatica, no. 5 (January 1, 2015): 115. http://dx.doi.org/10.15291/ars.521.
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The article analyses the illuminations of two incunables which are housed in the monastery of St Francis at Šibenik. The front page of the incunable of John Duns Scotus’ Scriptum in quattuor libros Sententiarum Petri Lombardi (Johannes de Colonia et Johannes Manthen, Venice, 1477) is decorated with high-quality figural and phytomorphic illuminations. In the corners of the decorative frame in the upper margin are the figures of a heronand a monkey. Vertical sections of the frame are filled with flowers, leaves and berries in the colour blue, green and cyclamen pink and with numerous stylized golden burdock flowers (Arctium). The central part of the frame in the upper and lower margin is filled with dense, symmetrically placed thick leaves in the colour blue, green, purple and cyclamen pink with a stylized golden burdockflower (Arctium) appearing here and there. In the centre of the page is a crest composed of two fields separated by a horizontal line; the upper on is red and the lower one white. Two winged putti are set in the corners andthey hold red ribbons. Each wears a necklace made of red corals and classical sandals on their feet. They landscape around them is arid and there is only one tree, its bark dry, standing in it. The rocky ground with jagged edges is covered in small stones. The distinctly painted winged putti, the depiction of the landscape and the dense vegetal decoration filling the frame in the upper and lower margin demonstrate noticeable similarities with the works of Giovanni Vendramin, a prominent representative of Paduan Renaissance miniature. Thefront page of the aforementioned incunable at Šibenik can be attributed to him; he may well have been helped by his workshop and collaborators. First and foremost, it ought to be mentioned that the decorative frame on one of the opening pages (c. 4v) in an Antiphonary at Ferrara features identical type of leaf decoration as the one that fills the upper and lower margin in the incunable at Šibenik. Here too, the playful putti wear classical sandals and necklaces made of red coral. Furthermore, putti with identical physiohnomies – wearing coral necklaces and classical sandals while holding ribbons in their hands – can be found on fol. 2r in the incunable of Marcus Tullius Cicero’s Orationes (Venice, Christophorus Valdarfer, 1471, Philadelphia, The Rosenbach Museum and Library, Inc 471ci). The landscape in which the putti are depictedis also arid and marked by a single dry tree rising from the ground covered with small stones. Identical putti can be seen on the cover of the incunable of Marcus Tullius Cicero’s, Tusculanae Quaestiones (Venice, N. Jenson, 1472, London, British Library, C.1c.10, fol. 1). The landscape is also depicted in the same way. An excellent comparative example can be found in the winged putti standing on an all’antica structure on the cover of the manuscript of Jacopo Camphora’s, De immortalitate animae (London, Brittish Library, MS Add. 22325) which is decorated with architectural forms. The left and the upper margins of the opening pages of Book I and Book III of Gaius Julius Caesar’s Commentariorvm de bello Gallico (Milan, Antonius Zarotus, 1477) are decorated with frames filled with white vine scrolls on red, green and blue background with white dots. The decoration extends beyond the ornamental frames and reaches into the gold initials G and C. Although the decorative frames were not completely finished, it can be ascertained that they were made with great skill and are of high quality. This frame type was frequently used by Giovanni Vendramin and the examples from Šibenik are very close to some of his works, especially those made for Jacopo Zeno, the Bishop of Padua (Padua, Biblioteca Capitolare).
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Sun, Dong-Sheng, Fa-Lin Lu, Yuan You, Chang-Yuan Chen, and Shi-Hai Dong. "Parity inversion property of the double ring-shaped oscillator in cylindrical coordinates." Modern Physics Letters A 30, no. 39 (December 7, 2015): 1550200. http://dx.doi.org/10.1142/s0217732315502004.
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Using the functional analysis method, we present the exact solutions of the double ring-shaped oscillator (DRSO) potential with certain parity in the cylindrical coordinates. Such a quantum system is separated to two differential equations, i.e. a one-dimensional harmonic oscillator plus an inverse square term and a two-dimensional harmonic oscillator plus an inverse square term. The key point is how to find the adapted symmetrical solutions of the one-dimensional harmonic oscillator plus an inverse square term at the singular point [Formula: see text]. The obtained results are compared with those in the spherical coordinates. We also explore intimate connections [Formula: see text] and [Formula: see text] by substituting [Formula: see text] and [Formula: see text].
Dissertations / Theses on the topic "Symmetrically separated set"
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RUSSO, TOMMASO. "ON SOME OPEN PROBLEMS IN BANACH SPACE THEORY." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/609289.
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The main line of investigation of the present work is the study of some aspects in the analysis
of the structure of the unit ball of (infinite-dimensional) Banach spaces. In particular,
we analyse some questions concerning the existence of suitable renormings that allow the
new unit ball to possess a specific geometric property. The main part of the thesis is,
however, dedicated to results of isometric nature, in which the original norm is the one
under consideration.
One of the main sources for the selection of the topics of investigation has been the
recent monograph [GMZ16], entirely dedicated to collecting several open problems in
Banach space theory and formulating new lines of investigation. We take this opportunity
to acknowledge the authors for their effort, that offered such useful text to the
mathematical community. The results to be discussed in our work actually succeed in
solving a few of the problems presented in the monograph and are based on the papers
[HáRu17, HKR18, HáRu19, HKR••].
Let us say now a few words on how the material is organised. The thesis is divided
in four chapters (some whose contents are outlined below) which are essentially independent
and can be read in whatsoever order. The unique chapter which is not completely
independent from the others is Chapter 4, where we use some results from Chapter 2 and
which is, in a sense, the non-separable prosecution of Chapter 3. However, cross-references
are few (never implicit) and usually restricted to quoting some result; it should therefore
be no problem to start reading from Chapter 4.
The single chapters all share the same arrangement. A first section is dedicated to an
introduction to the subject of the chapter; occasionally, we also present the proof of known
results, in most cases as an illustration of an important technique in the area. In these
introductions we strove to be as self-contained as possible in order to help the novel reader
to enter the field; consequently, experts in the area may find them somewhat redundant
and prefer to skip most parts of them.
The first section of each chapter concludes with the statement of our most significant
results and a comparison with the literature. The proofs of these results, together with
additional results or generalisations, are presented in the remaining sections of the chapter.
These sections usually follow closely the corresponding articles (carefully referenced) where
the results were presented.
Book chapters on the topic "Symmetrically separated set"
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Adda, Faycal. "Apparent Measure, Integral of Real Order, and Relative Dimension." In Advanced Applications of Fractional Differential Operators to Science and Technology, 283–320. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-3122-8.ch013.
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In this chapter, the author introduces a concept of apparent measure in R^n and associates the concept of relative dimension (of real order) that depends on the geometry of the object to measure and on the distance that separates it from an observer. At the end, the author discusses the relative dimension of a Cantor set. This measure enables us to provide a geometric interpretation of the Riemann-Liouville's integral of order αϵ├]0,1], and based on this interpretation, the author introduces a modification on the Riemann-Liouville's integral to make it symmetrical and then introduces a new fractional derivative that exploits at the same time the right and the left fractional derivatives.
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Graham, Alan. "Origins of North American Biogeographic Affinities." In Late Cretaceous and Cenozoic History of North American Vegetation (North of Mexico). Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195113426.003.0012.
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An aspect of plant distribution that has intrigued biogeographers for over 200 years is the occurrence of similar biotas in widely separated regions. The North American flora has affinities with several such areas: the Mediterranean, the dry regions of South America, eastern Asia, and eastern Mexico. The origin of some patterns is relatively clear, while for others hypotheses are just now being formulated. During times when the dogma of permanence of continents and ocean basins held sway, explanations for these disjunctions required imaginative thinking that often bordered on the bizarre. The pendulum or schwingpolen hypothesis was offered to explain the perceived bipolar distribution of several taxa (Gnetum, Magnolia, Pinus section Taeda; Simroth, 1914). By this view, the Earth swings in space like a pendulum, creating regular fluctuations in environments and often causing the symmetrical placement of taxa at two points on opposite sides of the Earth. Other disjunctions were explained by casually placing geophysically impossible land bridges at any point in time between any two sites where the presence of similar communities seemed to call for land connections (see review in Simpson, 1943). The presence of teeth of Hipparion, an ungulate related to the horse, in Europe and South Carolina-Florida prompted French geologist Leonce Joleaud to propose a land bridge extending from Florida through the Antilles to North Africa and Spain. Subsequently, to accommodate eight new passengers, it was broadened to encompass the entire region from Maryland and Brazil across to France and Morocco and its life was prolonged to include virtually all of the Tertiary. With the later discovery that there were periodicities in similarity between Old World and New World Cenozoic faunas, the continents were envisioned as moving back and forth like an accordion. George Gaylord Simpson, who favored the North Atlantic land bridge to connect North America and Europe, was beside himself with these theories and characterized Joelaud’s as “the climax of all drift theories.” The bridge became well established in the literature even though it never existed in the Atlantic Ocean (Marvin, 1973). Udvardy (1969) plotted all the Cretaceous and Tertiary land bridges postulated for the South Pacific up to 1913.
Conference papers on the topic "Symmetrically separated set"
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Uzol, Og˘uz, Xue Feng Zhang, Alex Cranstone, and Howard Hodson. "Investigation of Unsteady Wake-Separated Boundary Layer Interaction Using Particle-Image-Velocimetry." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-28099.
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The current paper presents an experimental investigation of the interaction between unsteady wakes and the separated boundary layer on the suction side of an ultra-high-lift low-pressure turbine airfoil. Two-dimensional Particle Image Velocimetry (PIV) measurements of the unsteady boundary layer over the T106C LP turbine profile were performed in a low speed linear cascade facility, at selected phases of passing wakes. The wakes are created by moving cylindrical bars across the inlet of the test section. Various phenomena were investigated such as separation and transition characteristics, vortex structures within the unsteady boundary layer, their interaction and effects on the transition process, the corresponding vortex shedding mechanisms and the unsteady behaviour of the separation bubble due to the wake- boundary layer interaction. The current measurements suggest that rollup vortices are generated as the wake approaches the separated shear layer on the suction surface before the wake centerline starts impinging on the blade. At this instant, the bubble is sufficiently high for the free shear layer to roll up into a vortex and the incoming wake is highly distorted (strained) due to the velocity field within the blade passage, and the turbulence distribution within the wake is not symmetrical. Vortices within the boundary layer, identified using the swirl strength distributions calculated from the eigenvalues of the velocity gradient tensor, seem to be coalescing and forming bigger scale structures, which in turn break up into smaller but higher swirl strength eddies. In between the passing wakes, the separation bubble grows in both in height and length, trying to return to its steady state shape.
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Baheri, S., B. A. Jubran, and S. P. Alavi Tabrizi. "The Effect of Turbulence Intensity on Film Cooling of Gas Turbine Blade From Trenched Shaped Holes." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50318.
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This paper reports a computational investigation on the effects of mainstream turbulence intensity on film cooling effectiveness from trenched holes over a symmetrical blade. Computational solutions of the steady, Reynolds-Averaged Navier-Stokes equations are obtained using a finite volume method with k – ε Turbulence model. Whenever possible, computational results are compared with experimental ones from data found in the open literature. Computational results are presented for a row of 25 deg forward-diffused film hole within transverse slot injected at 35 deg to AGTB symmetrical blade. Four blowing ratios, M = 0.3, 0.5, 0.9 and 1.3 are studied together with four mainstream turbulence intensities of Tu = 0.5%, 2%, 4% and 10%. Results indicate that the trenched shaped holes tend to give better film cooling effectiveness than that obtained from discrete shaped holes for all blowing ratios and all turbulence intensities. The trenching of shaped holes has changed the optimum blowing ratio and also the location of re-attachment of separated jet at high blowing ratios. Moreover, it has been found that the effect of mainstream turbulence intensity for trenched shaped holes is similar to that obtained for discrete shaped holes with the exception that the sensitivity of film cooling effectiveness to turbulence intensity has decreased for trenched shaped holes.
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Clayton, Alan M., and Thomas A. Duffey. "Protection Against Local Failure for Impulsively Loaded Vessels." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97043.
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Significant changes were recently made in design limits for pressurized vessels in Section VIII, Division 3 of the ASME Code. There is now a local damage-mechanics based strain-exhaustion limit as well as a separate global plastic collapse limit. In addition, Code Case 2564 (Sec VIII, Div 3) has recently been approved to address impulsively loaded vessels. Recent studies have shown that local strain limits play a particularly important role for these impulsively loaded vessels. In this paper, the new local strain-exhaustion procedure, originally intended for static-pressure-loaded vessels, is evaluated for adequacy in conservatively predicting failure for impulsively loaded vessels. Based upon a symmetrically loaded cylindrical shell geometry, it is found that direct extension of the new local failure rules in the ASME Code to impulsively loaded vessels is unconservative. However, a hoop-strain local failure criterion predicts failures reasonably well.
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Gao, Meng, and Lin Gui. "Possibility and Mechanism Study of Liquid-Metal Based Micro Electroosmotic Flow Pumps for Long-Time Running Purpose." In ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icnmm2015-48307.
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This work is a further study of our previous work on liquid-metal based micro electroosmotic flow pump. Injection of room temperature liquid metal (gallium alloy) into microchannels can provide a simple, rapid and low-cost technique for electrode fabrication of electroosmotic flow pumps. In the micro electroosmotic flow pump, the electrode channels are fabricated symmetrically to both sides of the pumping channel in the same horizontal level. In the micropump, PDMS was used to fabricate the microfluidic chip and the liquid metal channel was separated from the pumping channel by a PDMS gap (≤40μm). Although the PDMS is insulative, small current was still found when voltage was applied on the electrodes and the electrical field successfully drove the fluid in the pumping channel. This liquid-metal based micropump can be very easy for fabrication and integration. This study is focused on the possibility and mechanism study of this liquid-metal based EOF pump to see if it can be used for long-time running. The experimental study shows that the pump works very stable and perfect for long-time running applications such as implantable medical devices.
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Townsend, Todd, Will Moss, Dennis Heinisch, Kenneth Evans, and Cecil Schandorf. "Advanced High Frequency In-Bit Vibration Measurement Including Independent, Spatially Separated Sensors for Proper Resolution of Vibration Components Including Lateral, Radial, and Tangential Acceleration." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/208110-ms.
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Abstract Vibration measurement has become ubiquitous in drilling. Focus of drilling enhancement has expanded from traditional lateral and stick slip assessment to include torsional oscillations on motors, and high-frequency torsional oscillations (HFTO). Recent publications have highlighted the importance of these higher frequency measurements to analyze drilling dynamics and diagnose dysfunctions which can cause tool failures. A new vibration recorder will be presented which is capable of sampling at 2 kHz and higher to analyze non-linear transient dysfunctions. Most in-bit vibration measurement options utilize a single unsynchronized triaxial accelerometer and low speed gyro. This design practice inherits specific challenges to the measurement and prevents the ability to decouple lateral from angular acceleration. Use of two sets of symmetrically placed (180 degree opposing) accelerometers has been in practice, but design constraints limit this approach to larger bits. Utilization of a new, outer diameter (OD) mounted vibration recorder for slim hole bits/BHAs with multiple spatially separated triaxial accelerometers, and a high-speed precision gyro will be described and evaluated with a comparison to other commercially available options. Downhole vibration recorders have existed for over 20 years providing conventional drilling dynamics evaluation. These devices suffered from hardware limitations which constrained the customer to spaced out snapshots of time rather than continuous observation and required separate research modules to cover high frequency needs. This paper presents case studies utilizing a new vibration recorder which can cover these two customer needs in one device. Drilling Engineers desire a rapid turnaround macro view of synchronized downhole and surface data for offset well parameter optimization while research engineers desire a micro view with kilohertz range sample rate for a comprehensive understanding of all possible dysfunctions including HFTO, and high frequency shock, along with the capacity to research geology prediction techniques including fracture identification. Use of an advanced cloud-based software suite will be illustrated for a rapid high-level view of the full run with benchmarking capability of offset wells. Case study observations include stick slip identification covering 0 to above 600 rpm using a single gyroscope, and HFTO identification with accurate decoupling of tangential acceleration vs radial and lateral. Having the ability to satisfy both objectives with one device is new to the industry and presents a step change in capability. A new, advanced vibration recorder is detailed which includes synchronized, spatially separated triaxial accelerometers, a triaxial shock sensor, a highspeed triaxial gyroscope, and temperature sensors. With 5 gigabytes of high temperature flash memory, more than 2 kHz sample rate for burst data and 1s period for downhole processed data, logged downhole recordings can cover greater than 200 hrs of drilling and may be available for analysis within minutes from drilling completion.
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Fisch, E. E., Neal B. Abraham, L. M. Hoffer, and R. S. Gioggia. "Experimental measurements of the nonlinear dynamics of a laser with an injected signal." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.fw4.
Full textAbstract:
A unidirectional ring laser operated on the 3.51-μm transition in xenon has been studied for its behavior under injection of a constant intensity signal from a separate single-mode laser. The combined output variously shows simple beating (heterodyne mixing of the two lasers in the infrared detector) and more complicated nonlinear interactions that lead to pulsations and locking. Nonlinear interaction is indicated by the appearance of harmonics of the free-running laser beat frequency which result in nonsinusoidal intensity pulsations. A stronger indicator of the nonlinear interaction is found in the heterodyne spectrum where we see clear evidence that the injected signal is joined by a new optical frequency component symmetrically located with respect to the ring laser frequency. The degree of nonlinear interaction depends principally on the frequency difference between the two initial frequencies of the free-running lasers. The strength of the injected field also helps to determine the exact nature of the interaction. As the degree of homogeneous broadening of the xenon transition can be varied with the buffer gas (helium) pressure, various parameter-dependent details of the system have been determined for comparison with recent theoretical and numerical results.