Energy Technology Data Exchange (ETDEWEB)
Bassan, Massimo [Dipartimento di Fisica, Università di Roma Tor Vergata, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy); De Marchi, Fabrizio, E-mail: fabrizio.demarchi@roma2.infn.it [Dipartimento di Fisica, Università di Roma Tor Vergata, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy); Marconi, Lorenzo [Dipartimento di Fisica ed Astronomia, Università degli Studi di Firenze, and INFN, Sezione di Firenze (Italy); Pucacco, Giuseppe [Dipartimento di Fisica, Università di Roma Tor Vergata, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy); Stanga, Ruggero [Dipartimento di Fisica ed Astronomia, Università degli Studi di Firenze, and INFN, Sezione di Firenze (Italy); Visco, Massimo [IAPS-INAF, and INFN, Sezione di Roma Tor Vergata, I-00133 Roma (Italy)
2013-10-01
We present an analysis of the motion of a simple torsion pendulum and we describe how, with straightforward extensions to the usual basic dynamical model, we succeed in explaining some unexpected features we found in our data, like the modulation of the torsion mode at a higher frequency and the frequency splitting of the swinging motion. Comparison with observed values yields estimates for the misalignment angles and other parameters of the model.
Electrostatically suspended torsion pendulum
Willemenot, E.; Touboul, P.
2000-01-01
A torsion pendulum without a torsion wire has been designed and realized, in order to measure very weak forces. The arm of this torsion pendulum (5.40 g, 1.32×10-6 kg m2 of inertia) is electrostatically suspended. Its 6 degrees of freedom are controlled thanks to electrostatic forces, and capacitive position sensing with a noise spectral density between 10-10 and 10-13 m/√Hz . The torque noise spectral density is 1.3×10-14 Nm/√Hz around 0.05 Hz with a 1/√f increase at lower frequency, corresponding to 10-8 rad/s2/√Hz , and 2×10-10 ms-2/√Hz with a lever arm of 2 cm. The residual seismic noise limit the performances above 0.1 Hz. The free oscillating mode has a torsion stiffness of 5.14×10-8 Nm/rad and a Q of 217. This new instrument allows on ground experiments on very weak parasitic forces inside space accelerometers developed in ONERA, with a good representativeness. For example, it is possible to measure electrostatic stiffnesses with high resolution thanks to the low torque noise spectral density; the electrostatic damping phenomenon is also well seen as illustrated by the rather low Q. The instrument design and operation are described, the main performances are given, and the possibilities offered are discussed.
University of Florida Torsion Pendulum for Testing Key LISA Technology
Apple, Stephen; Chilton, Andrew; Olatunde, Taiwo Janet; Hillsberry, Daniel; Parry, Samantha; Ciani, Giacomo; Wass, Peter; Mueller, Guido; Conklin, John
2018-01-01
This presentation will describe the design and performance of a new torsion pendulum at the University of Florida used for testing inertial sensors and associated technologies for use in space – based gravitational wave observatories and geodesy missions. In particular this new torsion pendulum facility is testing inertial sensors and associated technology for the upcoming LISA (laser interferometer space antenna) space-based gravitational wave observatory mission. The torsion pendulum apparatus is comprised of a suspended cross bar assembly that has LISA test mass mockups at each of its ends. Two of the test mass mockups are enclosed by capacitive sensors which provide actuation and position sensing. The entire assembly is housed in a vacuum chamber. The pendulum cross-bar converts rotational motion of the test masses about the suspension fiber axis into translational motion. The 22 cm cross bar arm length along with the extremely small torsional spring constant of the suspension fiber results in a near free fall condition in the translational degree-of-freedom orthogonal to both the member and the suspension fiber. The test masses are electrically isolated from the pendulum assembly and their charge is controlled via photoemission using fiber coupled UV LEDS. Position of the test masses is measured using both capacitive and interferometric readout. The broadband sensitivity of the capacitive readout and laser interferometer readout is 30 nm/√Hz and 0.5 nm/√Hz respectively. The performance of the pendulum measured in equivalent acceleration noise acting on a LISA test mass is approximately 3 × 10-13 ms-2/√Hz at 2 mHz. This presentation will also discuss the design and fabrication of a flight-like gravitational reference sensor that will soon be integrated into the torsion pendulum facility. This flight-like GRS will allow for noise performance measurements in a more LISA-like configuration.
Static balancing of an inverted pendulum with prestressed torsion bars
Radaelli, G.; Buskermolen, R; Barents, R; Herder, J.L.
2017-01-01
This paper presents a method for the design of a statically balanced inverted pendulum. The non-linear moment-rotation characteristic of the pendulum's weight is approximated by a piecewise linear characteristic. Each transition is realized by engaging or disengaging one or more torsion bars, by
Torsion Pendulum Experiment at the International Physics Olympiad
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 6. Torsion Pendulum Experiment at the International Physics Olympiad. Sandeep Bala. Classroom Volume 5 Issue 6 June 2000 pp 76-85. Fulltext. Click here to view fulltext PDF. Permanent link:
A new torsion pendulum for gravitational reference sensor technology development.
Ciani, Giacomo; Chilton, Andrew; Apple, Stephen; Olatunde, Taiwo; Aitken, Michael; Mueller, Guido; Conklin, John W
2017-06-01
We report on the design and sensitivity of a new torsion pendulum for measuring the performance of ultra-precise inertial sensors and for the development of associated technologies for space-based gravitational wave observatories and geodesy missions. The apparatus comprises a 1 m-long, 50 μm-diameter tungsten fiber that supports an inertial member inside a vacuum system. The inertial member is an aluminum crossbar with four hollow cubic test masses at each end. This structure converts the rotation of the torsion pendulum into translation of the test masses. Two test masses are enclosed in capacitive sensors which provide readout and actuation. These test masses are electrically insulated from the rest of the crossbar and their electrical charge is controlled by photoemission using fiber-coupled ultraviolet light emitting diodes. The capacitive readout measures the test mass displacement with a broadband sensitivity of 30 nm∕Hz and is complemented by a laser interferometer with a sensitivity of about 0.5 nm∕Hz. The performance of the pendulum, as determined by the measured residual torque noise and expressed in terms of equivalent force acting on a single test mass, is roughly 200 fN∕Hz around 2 mHz, which is about a factor of 20 above the thermal noise limit of the fiber.
Conklin, John; Chilton, Andrew; Olatunde, Taiwo; Apple, Stephen; Aitken, Michael; Ciani, Giacomo; Mueller, Guido
2016-01-01
The Laser Interferometer Space Antenna (LISA) is the most mature concept for detecting gravitational waves from space. The LISA design has been studied for more than 20 years as a joint effort between NASA and the European Space Agency. LISA consists of three Sun-orbiting spacecraft that form an equilateral triangle, with each side measuring 1-5 million kilometers in length. Each spacecraft houses two free-floating test masses, which are protected from all disturbing forces so that they follow pure geodesics. A single test mass together with its protective housing and associated components is referred to as a gravitational reference sensor. A drag-free control system is supplied with measurements of the test mass position from these sensors and commands external micronewton thrusters to force the spacecraft to fly in formation with the test masses. Laser interferometry is used to measure the minute variations in the distance, or light travel time, between these purely free-falling TMs, caused by gravitational waves. We have constructed a new torsion pendulum facility with a force sensitivity in the range of pN/Hz1/2 around 1 mHz for testing new gravitational reference sensor technologies. This experimental facility consists of a vacuum enclosed torsion pendulum that suspends mock-ups of the LISA test masses, surrounded by their electrode housings. With the aid of this facility, we are (a) developing a novel test mass charge control scheme based on ultraviolet LEDs, (b) examining alternate test mass and electrode housing coatings, and (c) evaluating alternate operational modes of the LISA gravitational reference sensor. This presentation will describe this facility and the development status of these new technologies.
International Nuclear Information System (INIS)
San Juan, J. M.; Gallego, I.; No, M. L.
2001-01-01
In this work we describe the assembly, operation and specifications of an inverted torsion pendulum designed to measure internal friction at low temperatures (from 4.2 K to 500 K). The high precision mechanics allow us to obtain internal friction spectra with low levels of noise from amplitudes as small as 2x10''7. The inertia components of the pendulum have been built with specific materials, so that the resonance frequency of the pendulum can be changed within two orders of magnitude (0.1-10Hz). In addition, the sample can be in situ deformed at any temperature and can be inserted into the pendulum at liquid nitrogen temperature. The operation of the pendulum, all the control p recesses and data acquisition are completely automated. (Author) 4 refs
A New Inverted Torsion Pendulum-Based Mechanical Spectrometer to Study Soft Matter
Directory of Open Access Journals (Sweden)
Lei M.L.
2016-03-01
Full Text Available A new multifunctional mechanical spectrometer is developed based on an inverted torsion pendulum showing high precision in a wide frequency range to study soft matter. Apart from measuring the internal friction of solids it can also be used to study viscoelasticity. In this report we describe basic principles of the novel instrument.
Startsev, V. O.; Lebedev, M. P.; Molokov, M. V.
2018-03-01
A method to measure the glass-transition temperature of polymers and polymeric matrices of composite materials with the help of an inverse torsion pendulum over a wide range of temperatures is considered combining the method of free torsional vibrations and a quasi-static torsion of specimens. The glass-transition temperature Tg of a KMKS-1-80. T10 fiberglass, on increasing the frequency of freely damped torsional vibrations from 0.7 to 9.6 Hz, was found to increase from 132 to 140°C. The value of Tg of these specimens, determined by measuring the work of their torsion through a small fixed angle was 128.6°C ± 0.8°C. It is shown that the use of a torsion pendulum allows one to determine the glass-transition temperature of polymeric or polymer matrices of PCMs in dynamic and quasi-static deformation regimes of specimens.
An improved correlation method for determining the period of a torsion pendulum
International Nuclear Information System (INIS)
Luo Jie; Wang Dianhong
2008-01-01
Considering variation of environment temperature and unhomogeneity of background gravitational field, an improved correlation method was proposed to determine the variational period of a torsion pendulum with high precision. The result of processing experimental data shows that the uncertainty of determining the period with this method has been improved about twofolds than traditional correlation method, which is significant for the determination of gravitational constant with time-of-swing method.
Shelley, Ryan; Chilton, Andrew; Olatunde, Tawio; Ciani, Giacomo; Mueller, Guido; Conklin, John
2014-03-01
The Laser Interferometer Space Antenna (LISA) requires free falling test masses, whose acceleration must be below 3 fm/s2/rtHz in the lower part of LISA's frequency band ranging from 0.1 to 100 mHz. Gravitational reference sensors (GRS) house the test masses, shield them from external disturbances, control their orientation, and sense their position at the nm/rtHz level. The GRS torsion pendulum is a laboratory test bed for GRS technology. By decoupling the system of test masses from the gravity of the Earth, it is possible to identify and quantify many sources of noise in the sensor. The mechanical design of the pendulum is critical to the study of the noise sources and the development of new technologies that can improve performance and reduce cost. The suspended test mass is a hollow, gold-coated, aluminum cube which rests inside a gold-coated, aluminum housing with electrodes for sensing and actuating all six degrees of freedom. This poster describes the design, analysis, and assembly of the mechanical subsystems of the UF Torsion Pendulum.
Energy Technology Data Exchange (ETDEWEB)
San Juan, J. M.; Gallego, I.; No, M. L.
2001-07-01
In this work we describe the assembly, operation and specifications of an inverted torsion pendulum designed to measure internal friction at low temperatures (from 4.2 K to 500 K). The high precision mechanics allow us to obtain internal friction spectra with low levels of noise from amplitudes as small as 2x10''7. The inertia components of the pendulum have been built with specific materials, so that the resonance frequency of the pendulum can be changed within two orders of magnitude (0.1-10Hz). In addition, the sample can be in situ deformed at any temperature and can be inserted into the pendulum at liquid nitrogen temperature. The operation of the pendulum, all the control p recesses and data acquisition are completely automated. (Author) 4 refs.
Zhang, Nan; Wang, Wentao; Zhu, Xiaonong; Liu, Jiansheng; Xu, Kuanhong; Huang, Peng; Zhao, Jiefeng; Li, Ruxin; Wang, Mingwei
2011-04-25
50 fs - 12 ps laser pulses are employed to ablate aluminum, copper, iron, and graphite targets. The ablation-generated momentum is measured with a torsion pendulum. Corresponding time-resolved shadowgraphic measurements show that the ablation process at the optimal laser fluence achieving the maximal momentum is primarily dominated by the photomechanical mechanism. When laser pulses with specific laser fluence are used and the pulse duration is tuned from 50 fs to 12 ps, the generated momentum firstly increases and then remains almost constant, which could be attributed to the change of the ablation mechanism involved from atomization to phase explosion. The investigation of the ablation-generated momentum also reveals a nonlinear momentum-energy conversion scaling law, namely, as the pulse energy increases, the momentum obtained by the target increases nonlinearly. This may be caused by the effective reduction of the dissipated energy into the surrounding of the ablation zone as the pulse energy increases, which indicates that for femtosecond laser the dissipated energy into the surrounding target is still significant.
Russano, G.; Cavalleri, A.; Cesarini, A.; Dolesi, R.; Ferroni, V.; Gibert, F.; Giusteri, R.; Hueller, M.; Liu, L.; Pivato, P.; Tu, H. B.; Vetrugno, D.; Vitale, S.; Weber, W. J.
2018-02-01
LISA Pathfinder is a differential accelerometer with the main goal being to demonstrate the near perfect free-fall of reference test masses, as is needed for an orbiting gravitational wave observatory, with a target sensitivity of 30 fm s‑2 Hz-1/2 at 1 mHz. Any lasting background differential acceleration between the two test masses must be actively compensated, and noise associated with the applied actuation force can be a dominant source of noise. To remove this actuation, and the associated force noise, a ‘free-fall’ actuation control scheme has been designed; actuation is limited to brief impulses, with both test masses in free-fall in the time between the impulses, allowing measurement of the remaining acceleration noise sources. In this work, we present an on-ground torsion pendulum testing campaign of this technique and associated data analysis algorithms at a level nearing the sub-femto-g/\\sqrtHz performance required for LISA Pathfinder.
Bassan, M.; Cavalleri, A.; De Laurentis, M.; De Marchi, F.; De Rosa, R.; Di Fiore, L.; Dolesi, R.; Finetti, N.; Garufi, F.; Grado, A.; Hueller, M.; Marconi, L.; Milano, L.; Minenkov, Y.; Pucacco, G.; Stanga, R.; Vetrugno, D.; Visco, M.; Vitale, S.; Weber, W. J.
2018-01-01
In this paper we report on measurements on actuation crosstalk, relevant to the gravitational reference sensors for LISA Pathfinder and LISA. In these sensors, a Test Mass (TM) falls freely within a system of electrodes used for readout and control. These measurements were carried out on ground with a double torsion pendulum that allowed us to estimate both the torque injected into the sensor when a control force is applied and, conversely, the force leaking into the translational degree of freedom due to the applied torque.The values measured on our apparatus (the engineering model of the LISA Pathfinder sensor) agree to within 0.2% (over a maximum measured crosstalk of 1%) with predictions of a mathematical model when measuring force to torque crosstalk, while it is somewhat larger than expected (up to 3.5%) when measuring torque to force crosstalk. However, the values in the relevant range, i.e. when the TM is well centered ( ± 10 μm) in the sensor, remain smaller than 0.2%, satisfying the LISA Pathfinder requirements.
Barker, Bernard
2012-01-01
This article examines the New Labour legacy in education, reviews the arguments of "The Pendulum Swings" in the light of contributions to this themed issue, examines early Coalition policymaking, and recommends four principles that should guide the search for a new approach to school improvement. Recent initiatives are found to be a…
Directory of Open Access Journals (Sweden)
Jared Wynn
2010-01-01
Full Text Available The objective of this project is to derive and solve the equation of motion for a pendulum swinging at small angles in one dimension. The pendulum may be either a simple pendulum like a ball hanging from a string or a physical pendulum like a pendulum on a clock. For simplicity, we only considered small rotational angles so that the equation of motion becomes a harmonic oscillator.
Analysis and simulation of centrifugal pendulum vibration absorbers
Smith, Emma
2015-01-01
When environmental laws are constricted and downsizing of engines has become the reality of the vehicle industry, there needs to be a solution for the rise in torsion vibrations in the drivetrain. These increased levels of torsion vibrations are mostly due to excitations from the firing pulses, which in turn have become increased due to higher cylinder pressures. One of the solutions for further dampening the system is to add a centrifugal pendulum absorber to the flywheel, and predicting the...
Block, Daniel J; Spong, Mark W
2007-01-01
This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t
Broadband pendulum energy harvester
Liang, Changwei; Wu, You; Zuo, Lei
2016-09-01
A novel electromagnetic pendulum energy harvester with mechanical motion rectifier (MMR) is proposed and investigated in this paper. MMR is a mechanism which rectifies the bidirectional swing motion of the pendulum into unidirectional rotation of the generator by using two one-way clutches in the gear system. In this paper, two prototypes of pendulum energy harvester with MMR and without MMR are designed and fabricated. The dynamic model of the proposed MMR pendulum energy harvester is established by considering the engagement and disengagement of the one way clutches. The simulation results show that the proposed MMR pendulum energy harvester has a larger output power at high frequencies comparing with non-MMR pendulum energy harvester which benefits from the disengagement of one-way clutch during pendulum vibration. Moreover, the proposed MMR pendulum energy harvester is broadband compare with non-MMR pendulum energy harvester, especially when the equivalent inertia is large. An experiment is also conducted to compare the energy harvesting performance of these two prototypes. A flywheel is attached at the end of the generator to make the disengagement more significant. The experiment results also verify that MMR pendulum energy harvester is broadband and has a larger output power at high frequency over the non-MMR pendulum energy harvester.
Directory of Open Access Journals (Sweden)
Siddharth Pramod Dubhashi
2016-01-01
Full Text Available Torsion of the vermiform appendix is a rare condition detectable only at operation. It can be primary or secondary. This is a case report of 52-year-old female with 180° anti-clockwise rotation of the appendix. Torsion can further leads to strangulation and infarction of the organ. Appendicular torsion could be included in the differential diagnosis of pain in right iliac fossa.
Fay, Temple H.
2002-01-01
We investigate the pendulum equation [theta] + [lambda][squared] sin [theta] = 0 and two approximations for it. On the one hand, we suggest that the third and fifth-order Taylor series approximations for sin [theta] do not yield very good differential equations to approximate the solution of the pendulum equation unless the initial conditions are…
African Journals Online (AJOL)
TESTICULAR TORSION: EXPERIENCE IN THE MIDDLE BELT OF NIGERIA. S.A. KURANGA AND G.A. RAHMAN. Department of Surgery, University of l/orin Teaching Hospital, Ilorin, Nigeria. Objective To determine the fate of the testis affected by testicular torsion (TT) in relation to the duration of the symptoms and to.
Gitterman, Moshe
2008-01-01
This book contains the general description of the mathematical pendulum subject to constant torque, periodic and random forces. The latter appear in additive and multiplicative form with their possible correlation. For the underdamped pendulum driven by periodic forces, a new phenomenon - deterministic chaos - comes into play, and the common action of this chaos and the influence of noise are taken into account. The inverted position of the pendulum can be stabilized either by periodic or random oscillations of the suspension axis or by inserting a spring into a rigid rod, or by their combinat
Hydride precipitation in zirconium studied by pendulum techniques
International Nuclear Information System (INIS)
Ritchie, I.G.; Sprungmann, K.W.
1983-12-01
Measurements of the precipitation peak, the autotwisting strain and the properties of hydride dislocations have been used to map the hydrogen terminal solid solubility boundary in polycrystalline samples and a single-crystal sample of α-zirconium. A low-frequency torsion pendulum was employed for some of the measurements and a low-frequency flexure pendulum for others. These pendulum techniques were successful in extending measurements of the hydrogen terminal solid solubility boundary in α-zirconium to the relatively low hydrogen concentration range 2 to 50 μg/g of technological interest in the nuclear industry. In addition, the results were used to obtain qualitative and quantitative information about the stress dependence of the hydrogen terminal solid solubility boundary and the kinetics of hydride precipitation or dissolution in response to a step change in the applied stress
Foucault Pendulum without Driving
Yamashita, Yoshifumi
2016-06-01
Foucault pendulums are two-dimensional harmonic oscillators to which the Coriolis force is applied. The Foucault parameter ΩF is the ideal rate of rotation of the plane of oscillation due to the Coriolis force. Kamerlingh Onnes pointed out that the actual behavior of Foucault pendulums can be understood only by taking into account the unavoidable mechanical asymmetry, i.e., the difference between the frequency in the X-direction and that in the Y-direction, which is called the asymmetry parameter δ. Our equations of motion for Foucault pendulums are linear and their solutions are easily obtained. We are interested in slowly varying rotations of the plane of oscillation, where the angle of rotation is denoted by φ. The motion of the bob consists of rapid simple oscillations and the slow rotations mentioned above. Eliminating the rapid oscillations, we obtain an analytic expression for tan 2φ, which is a periodic function with period π /√{Ω F2 + δ 2} . The graphs of the rotation φ versus time t have two distinct appearances. Under the condition ΩF ≥ δ|cos(2θ)| (θ is the initial value of φ), φ decreases monotonically, which is the behavior expected for Foucault pendulums. Otherwise φ repeatedly increases and decreases, which is the behavior of pendulums describing Lissajous figures. The vertical component of angular momentum is also calculated analytically.
International Nuclear Information System (INIS)
Lacsny, Boris; Štubna, Igor; Teleki, Aba
2014-01-01
A Foucault pendulum was assembled for a university/high-school physics course. The pendulum is 2.85 m long and the mass of the bob is 4.70 kg. A new technique based on the spark burned points on a sheet of paper was used to register the pendulum’s motion. A Ruhmkorff induction coil was used as a high-voltage source. Plots of the elliptical trajectories (except the first trajectory, which is a straight line) can be created and the angles between the major axes of the ellipses can be determined after assigning the coordinates to the burned points. (paper)
Lacsny, Boris; Štubna, Igor; Teleki, Aba
2014-11-01
A Foucault pendulum was assembled for a university/high-school physics course. The pendulum is 2.85 m long and the mass of the bob is 4.70 kg. A new technique based on the spark burned points on a sheet of paper was used to register the pendulum’s motion. A Ruhmkorff induction coil was used as a high-voltage source. Plots of the elliptical trajectories (except the first trajectory, which is a straight line) can be created and the angles between the major axes of the ellipses can be determined after assigning the coordinates to the burned points.
Pursuing the Ubiquitous Pendulum
Stinner, Art; Metz, Don
2003-01-01
In this paper, we offer three examples, inspired by Galileo's work, for connecting the physics of the pendulum with free fall and the inclined plane. The first example discusses the time it takes for a ball to slide down a frictionless inclined plane along a chord, drawn from the lowest point of a vertical circle to any point on the circle. The second example discusses a timing method that Galileo tested in measuring free fall directly, and the third example outlines an approach we have developed for accurately calculating the period of a pendulum for any angle, using only the kinematics of accelerated motion along an inclined plane, first studied by Galileo.
International Nuclear Information System (INIS)
Sharpe, Eric
2003-01-01
In this article we explain discrete torsion. Put simply, discrete torsion is the choice of orbifold group action on the B field. We derive the classification H 2 (Γ,U(1)), the twisted sector phases appearing in string loop partition functions, Douglas's description of discrete torsion for D-branes in terms of a projective representation of the orbifold group, and outline how the results of Vafa and Witten fit into this framework. In addition, we observe that additional degrees of freedom (known as shift orbifolds) appear in describing orbifold group actions on B fields, in addition to those classified by H 2 (Γ,U(1)), and explain how these degrees of freedom appear in terms of twisted sector contributions to partition functions and in terms of orbifold actions on D-brane worldvolumes. This paper represents a technically simplified version of prior papers by the author on discrete torsion. We repeat here technically simplified versions of results from those papers, and have included some new material
African Journals Online (AJOL)
A‑2/103, Shivranjan Towers, Someshwarwadi, Pashan, Pune ‑ 411 008,. Maharashtra, India. E‑mail: spdubhashi@gmail.com. INTRODUCTION. Acute appendicitis presents with pain in right iliac fossa. Torsion of the vermiform appendix, though rare, also presents in a similar fashion, and it is detectable only at operation.[1].
Bond, Trevor G.
Piaget's investigations into children's understanding of the laws governing the movement of a simple pendulum were first reported in 1955 as part of a report into how children's knowledge of the physical world changes during development. Chapter 4 of Inhelder & Piaget (1955/1958) entitled `The Oscillation of a Pendulum and the Operations of Exclusion'' demonstrated how adolescents could construct the experimental strategies necessary to isolate each of the variables, exclude the irrelevant factors and conclude concerning the causal role of length. This became one of the most easily replicable tasks from the Genevan school and was used in a number of important investigations to detect the onset of formal operational thinking. While it seems that the pendulum investigation fits nicely into Piaget's sequence of studies of concepts such as time, distance and speed suggested to him by Einstein, more recent research (Bond 2001) shows Inhelder to be directly responsible for the investigations into children's induction of physical laws. The inter-relationship between the pendulum problem, developing thought and scientific method is revealed in a number of Genevan and post-Piagetian investigations.
International Nuclear Information System (INIS)
Aldrovandi, R.; Ferreira, P.L.
1979-01-01
The problem of the mathematical pendulum is treated in its classical, semi-classical and quantum aspects. The Schroedinger equation of the problem is reduced to a Mathieu equation. The energy spectrum and eigenfunctions are discussed, with the requirement of single-valuedness imposed on them. Physical limiting cases are also discussed. (author) [pt
Mode competition in a system of two coupled, parametrically driven pendulums: the Hamiltonian case
Banning, E.J.; Banning, E.J.; van der Weele, J.P.
1995-01-01
We study the mode competition in a Hamiltonian system of two parametrically driven pendulums, linearly coupled by a torsion spring. First we make a classification of all the periodic motions in four main types: the trivial motion, two `normal modes¿, and a mixed motion. Next we determine the
Peculiar torsion dynamical response of spider dragline silk
Liu, Dabiao; Yu, Longteng; He, Yuming; Peng, Kai; Liu, Jie; Guan, Juan; Dunstan, D. J.
2017-07-01
The torsional properties of spider dragline silks from Nephila edulis and Nephila pilipes spiders are investigated by using a torsion pendulum technique. A permanent torsional deformation is observed after even small torsional strain. This behaviour is quite different from that of the other materials tested here, i.e., carbon fiber, thin metallic wires, Kevlar fiber, and human hair. The spider dragline thus displays a strong energy dissipation upon the initial excitation (around 75% for small strains and more for a larger strain), which correspondingly reduces the amplitude of subsequent oscillations around the new equilibrium position. The variation of torsional stiffness in relaxation dynamics of spider draglines for different excitations is also determined. The experimental result is interpreted in the light of the hierarchical structure of dragline silk.
DEFF Research Database (Denmark)
Brasso, K; Andersen, L; Kay, L
1993-01-01
Thirty-five patients were examined 6-11 years after operation for torsion of the testis. Loss of testicular tissue was significantly associated with long preoperative duration of symptoms and with low postoperative sperm counts. The sex hormones were normal in the majority of patients but there w...... to the sperm count and concentration. Measurement of carnitine levels in seminal plasma, as a sign of vas deferens obstruction or dysfunction of epididymis, and of autoantibodies against spermatozoa revealed no significant findings....
The Pendulum and the Calculus.
Sworder, Steven C.
A pair of experiments, appropriate for the lower division fourth semester calculus or differential equations course, are presented. The second order differential equation representing the equation of motion of a simple pendulum is derived. The period of oscillation for a particular pendulum can be predicted from the solution to this equation. As a…
DEFF Research Database (Denmark)
Thomsen, Jon Juel; Tcherniak, D. M.
2001-01-01
Chelomei´s pendulum has a sliding disc on its rod, and is mounted on a support that vibrates vertically with small amplitude and high frequency. In 1982, V. N. Chelomei demonstrated experimentally that a configuration can be stable where the pendulum points against gravity, and the disc ´floats...
Torsional Elastic Property Measurements of Selected Orthodontic Archwires.
1987-01-01
properties of denture base acrylics . 26 In this experiment, an inverted pendulum was hung by a fine, fixed wire. The amplitude and frequency of...of Polymers. Polymer Engineering and Science 19:664-675. 26. Braden M, Stafford GD: Viscoelastic Properties of Some Denture Base Materials. J Dent...D-AiB5 669 TORSIONAL ELASTIC PROPERTY MEASUREMENTSO SLECE ORTHODONTIC ARCHWlIRES(U) AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH B E LARSON 1987
Simple pendulum for blind students
Goncalves, A. M. B.; Cena, C. R.; Alves, D. C. B.; Errobidart, N. C. G.; Jardim, M. I. A.; Queiros, W. P.
2017-09-01
Faced with the need to teach physics to the visually impaired, in this paper we propose a way to demonstrate the dependence of distance and time in a pendulum experiment to blind students. The periodic oscillation of the pendulum is translated, by an Arduino and an ultrasonic sensor, in a periodic variation of frequency in a speaker. The main advantage of this proposal is the possibility that a blind student understands the movement without necessity of touching it.
The Pendulum A Case Study in Physics
Baker, Gregory L
2005-01-01
The pendulum: a case study in physics is a unique book in several ways. Firstly, it is a comprehensive quantitative study of one physical system, the pendulum, from the viewpoint of elementary and more advanced classical physics, modern chaotic dynamics, and quantum mechanics. In addition, coupled pendulums and pendulum analogs of superconducting devices are also discussed. Secondly, this book treats the physics of the pendulum within a historical and cultural context,showing, for example, that the pendulum has been intimately connected with studies of the earth's density, the earth's motion,
Spherical Pendulum, Actions, and Spin
Richter, Peter H.; Dullin, Holger R.; Waalkens, Holger; Wiersig, Jan
1996-01-01
The classical and quantum mechanics of a spherical pendulum are worked out, including the dynamics of a suspending frame with moment of inertia θ. The presence of two separatrices in the bifurcation diagram of the energy-momentum mapping has its mathematical expression in the hyperelliptic nature of
Pendulum Motion and Differential Equations
Reid, Thomas F.; King, Stephen C.
2009-01-01
A common example of real-world motion that can be modeled by a differential equation, and one easily understood by the student, is the simple pendulum. Simplifying assumptions are necessary for closed-form solutions to exist, and frequently there is little discussion of the impact if those assumptions are not met. This article presents a…
Pendulum migration and healthcare in border área.
Zaslavsky, Ricardo; Goulart, Bárbara Niegia Garcia de
2017-12-01
This article aims to reflect about the importance and the potential impact of pendulum migration in the pursuance for healthcare, and, specifically, about the peculiarity of this kind of mobility in border areas. It describes the context in which the pendulum migration is inserted for the modification of the urban space in the 20th century, makes initial comments about legal aspects of the theme in health sector, and describes the reality of the Brazil-Argentina-Paraguay triple border as an important location of pendulum migration for the pursuance of healthcare as an illustrative fact. In this way, hypotheses are formulated about the causes of the pendulum migration impact on patient's health like the effect of the distance covered from home to healthcare facilities, and organizational aspects related to healthcare like the uncertainty about having or not health assistance due to international mobility. It concludes that this kind of mobility is very common in the pursuance of healthcare despite the traditional approach to the theme mentioning only work or study. Besides that, it is very important to study its impact on health and to include this theme on the cross border healthcare debate.
Gallbladder torsion. Case report
DEFF Research Database (Denmark)
Brasso, K; Rasmussen, O V
1991-01-01
Gallbladder torsion is a rare surgical emergency occurring primarily in elderly women. The anatomical background is a variation in the attachment of the gallbladder to the inferior margin of the liver. Increasing life span will probably lead to an increasing number of cases, and gallbladder torsion...
Energy Technology Data Exchange (ETDEWEB)
Fresneda, R., E-mail: rodrigo.fresneda@ufabc.edu.br [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil); Baldiotti, M.C.; Pereira, T.S., E-mail: baldiotti@uel.br, E-mail: tspereira@uel.br [Universidade Estadual de Londrina (UEL), Londrina, PR (Brazil). Departamento de Fisica
2015-06-15
We propose a gauge-invariant model of propagating torsion which couples to the Maxwell field and to charged particles. As a result, we have an Abelian gauge-invariant action leading to a theory with nonzero torsion consistent with available experimental data, which can be used to establish a lower bound for our new coupling parameter. (author)
Directory of Open Access Journals (Sweden)
Yu-Hui Huang
2006-09-01
Conclusion: Splenic torsion is a rare cause of acute abdominal pain during pregnancy or postpartum, and the symptoms vary depending on the degree of torsion. Early involvement of many complementary specialty services enabled early recognition of this rare entity and timely definitive treatment.
Nonlinear Feedback Control of the Rotary Inverted Pendulum
2017-06-01
pendulum include wheeled mobile robots, which can be useful for personal mobility . C. PRIOR WORK There are nonlinear control techniques that have...results. Among the applications of the inverted pendulum is a two wheeled robot. One mobile inverted pendulum robot was created by Grasser, D’Arrigo... pendulum which could shift the weight of the load to keep the pendulum straight up when on a slope [10]. The work in mobile inverted pendulums can
International Nuclear Information System (INIS)
Denardo, G.; Spallucci, E.
1985-07-01
We study pregeometry in the framework of a Poincare gauge field theory. The Riemann-Cartan space-time is shown to be an ''effective geometry'' for this model in the low energy limit. By using Heat Kernel techniques we find the induced action for curvature and torsion. We obtain in this way the usual Einstein-Hilbert action plus an axial Maxwell term describing the propagation of a massless, axial vector torsion field. (author)
Mosna, Ricardo A.; Saa, Alberto
2005-11-01
We reexamine here the issue of consistency of minimal action formulation with the minimal coupling procedure (MCP) in spaces with torsion. In Riemann-Cartan spaces, it is known that a proper use of the MCP requires that the trace of the torsion tensor be a gradient, Tμ=∂μθ, and that the modified volume element τθ=eθ√g dx1∧⋯∧dxn be used in the action formulation of a physical model. We rederive this result here under considerably weaker assumptions, reinforcing some recent results about the inadequacy of propagating torsion theories of gravity to explain the available observational data. The results presented here also open the door to possible applications of the modified volume element in the geometric theory of crystalline defects.
Two often disregarded aspects of Foucault's pendulum
International Nuclear Information System (INIS)
Pérez, José-Philippe; Pujol, Olivier
2015-01-01
This paper revisits the famous Foucault's pendulum by highlighting two often-disregarded aspects in mechanics courses. The first one concerns the existence of a local accelerated reference frame to express the law of dynamics without the Coriolis force. The second aspect deals with the geometrical phase that appears in pendulum dynamics. This last point, which could appear banal, should be related to analogous consideration in quantum physics. It is also linked to vectorial parallel transport of the pendulum angular momentum eigenvector. Numerical simulations with MATLAB are proposed. (paper)
Three Spreadsheet Models Of A Simple Pendulum
Directory of Open Access Journals (Sweden)
Jan Benacka
2008-10-01
Full Text Available The paper gives three spreadsheet models of simple pendulum motion. In two of them, the graph of the pendulum angle is drawn upon the exact integral solution using numeric integration – the simpler model only uses spreadsheet functions, the general model uses a VBA program. The period results directly from the calculations. In the third model, the period is calculated first using the power series formula. The graph of the pendulum angle is drawn afterwards using Euler’s method of solving differential equations. The error in gravity acceleration if calculated upon the standard cosine approximate formula instead of the exact one is graphed.
International Nuclear Information System (INIS)
Wang, M C; Jiao, J W; Yan, P L; Mi, B W; Qin, S
2014-01-01
This paper presents a tri-axis MEMS gyroscope design with novel tetra-pendulum proof masses for X-, Y-axis and regular proof masses for Z-axis rate sensing, which are all coupled with and embedded in a conventional tuning fork driving frame. The four pendulum proof masses are suspended via the torsional springs to a common center anchor and can be driven to swing around the anchor via the tilted transforming springs as the driving frame is oscillated in an anti-phase mode. As an X-, Y-axis angular rate is applied, the tetra-pendulum proof masses will rotate around the torsional springs in pairs for X- and Y-axis differential sensing, respectively. In particular, we investigated the relationship between the tilting angle of the transforming spring and its transforming efficiency, i.e. the amplitude ratio of the pendulum's swing to the driving oscillation, which shows a straight impact on the sensitivity. By theoretical analysis and Ansys simulation, we achieved an optimal tilting angle of 22.5°, which extends along the angular bisector of the pendulum's and driving mass’ moving direction and demonstrates a significant increase in transforming efficiency by about 40%, compared with the trivial tilting angle of 45°. By employing an SOI-based bulk micromachining process, the prototype device with the optimal design of the transforming spring (type I) and that with the trivial design (type II) for reference have been successfully fabricated. As expected, the testing results indicate an increase of more than 20% in the X- and Y- sensitivities, which is mainly from the enhanced sensitive transforming springs. (paper)
Higher Franz-Reidemeister torsion
Igusa, Kiyoshi
2002-01-01
The book is devoted to the theory of topological higher Franz-Reidemeister torsion in K-theory. The author defines the higher Franz-Reidemeister torsion based on Volodin's K-theory and Borel's regulator map. He describes its properties and generalizations and studies the relation between the higher Franz-Reidemeister torsion and other torsions used in K-theory: Whitehead torsion and Ray-Singer torsion. He also presents methods of computing higher Franz-Reidemeister torsion, illustrates them with numerous examples, and describes various applications of higher Franz-Reidemeister torsion, particularly for the study of homology of mapping class groups. Packed with up-to-date information, the book provides a unique research and reference tool for specialists working in algebraic topology and K-theory.
Isolated Fallopian Tube Torsion
Directory of Open Access Journals (Sweden)
S. Kardakis
2013-01-01
Full Text Available Isolated torsion of the Fallopian tube is a rare gynecological cause of acute lower abdominal pain, and diagnosis is difficult. There are no pathognomonic symptoms; clinical, imaging, or laboratory findings. A preoperative ultrasound showing tubular adnexal masses of heterogeneous echogenicity with cystic component is often present. Diagnosis can rarely be made before operation, and laparoscopy is necessary to establish the diagnosis. Unfortunately, surgery often is performed too late for tube conservation. Isolated Fallopian tube torsion should be suspected in case of acute pelvic pain, and prompt intervention is necessary.
Period of an Interrupted Pendulum
Miller, Bradley E.
2002-11-01
While demonstrating a classic conservation-of-energy problem to my AP Physics students, I became curious about the periodic motion that ensued for certain initial conditions. The original problem consists of releasing a mass at the end of a string from an initial position horizontal to the plane of a table. The string comes in contact with a peg some distance below the point where the string is attached at the top. One is asked to find what minimum fraction of the string's length should the peg be placed to have the mass complete a circle about the peg. However, when the mass is released from much lower heights, the system undergoes periodic motion that can be thought of as an interrupted pendulum.
Barenboim, G.; Oteo, J. A.
2013-07-01
The analytical solution for the three-dimensional linear pendulum in a rotating frame of reference is obtained, including Coriolis and centrifugal accelerations, and expressed in terms of initial conditions. This result offers the possibility of treating Foucault and Bravais pendula as trajectories of the same system of equations, each of them with particular initial conditions. We compare them with the common two-dimensional approximations in textbooks. A previously unnoticed pattern in the three-dimensional Foucault pendulum attractor is presented.
International Nuclear Information System (INIS)
Barenboim, G; Oteo, J A
2013-01-01
The analytical solution for the three-dimensional linear pendulum in a rotating frame of reference is obtained, including Coriolis and centrifugal accelerations, and expressed in terms of initial conditions. This result offers the possibility of treating Foucault and Bravais pendula as trajectories of the same system of equations, each of them with particular initial conditions. We compare them with the common two-dimensional approximations in textbooks. A previously unnoticed pattern in the three-dimensional Foucault pendulum attractor is presented. (paper)
Cycloidal pendulum with a rolling cylinder
Legeza, V. P.
2012-07-01
Free vibrations of a heavy homogeneous cylinder rolling in a cylindrical cavity whose directing curve is a brachistochrone are considered. The equation of motion of the cylinder is derived and the circular frequency of free vibrations of the cylinder center of mass is determined. An analogy between the cycloidal pendulum with a rolling cylinder and the classical cycloidal pendulum in the form of a material point is obtained.
Ihrke, Chris A. (Inventor); Parsons, Adam H. (Inventor); Mehling, Joshua S. (Inventor); Griffith, Bryan Kristian (Inventor)
2012-01-01
A torsion spring comprises an inner mounting segment. An outer mounting segment is located concentrically around the inner mounting segment. A plurality of splines extends from the inner mounting segment to the outer mounting segment. At least a portion of each spline extends generally annularly around the inner mounting segment.
Testicular Torsion (For Parents)
... securing the testicles to the scrotum. If your son had a torsion that resulted in the loss of a testicle, it's important to let him know that he can still lead a normal life, just like anyone else. The loss of one testicle won't prevent a man from having normal sexual relations and is unlikely ...
Gallbladder torsion. Case report
DEFF Research Database (Denmark)
Brasso, K; Rasmussen, O V
1991-01-01
Gallbladder torsion is a rare surgical emergency occurring primarily in elderly women. The anatomical background is a variation in the attachment of the gallbladder to the inferior margin of the liver. Increasing life span will probably lead to an increasing number of cases, and gallbladder torsi...
African Journals Online (AJOL)
he had described a typical case in an 18 year old who later developed torsion of the contra-lateral testis and suffered ... he visited our hospital where an ultrasound scan was ordered, which was reported as showing an enlarged .... Mills S.E., Carter D., Reuter V.E., et al. Sternberg's diagnostic surgical pathology. 2004;4th.
International Nuclear Information System (INIS)
Aros, Rodrigo; Contreras, Mauricio
2006-01-01
In this work the Poincare-Chern-Simons and anti-de Sitter-Chern-Simons gravities are studied. For both, a solution that can be cast as a black hole with manifest torsion is found. Those solutions resemble Schwarzschild and Schwarzschild-AdS solutions, respectively
African Journals Online (AJOL)
are retractile and more mobility is at increased risk for torsion. An increased prevalence of carcinoma has also been reported.[1]. Case Report. A 72-year-old man presented with vague pain in the lower abdomen and scrotum. There was no history of trauma and he stated that the pain was severe in nature and had been ...
Torsional method for evaluating hair damage and performance of hair care ingredients.
Persaud, D; Kamath, Y K
2004-01-01
In this study, we have developed a single hair fiber torsional pendulum method to determine the role of the cuticle and the cortex on torsional properties with respect to fiber cross-sectional area, fiber rigidity, and energy dissipation at 65% RH and in the wet state. Our results demonstrate that in fine diameter fibers with a high cuticle-to-cortex ratio, the cuticula exert a significant effect on the torsional deformation behavior of hair fibers at both normal humidities and in the wet condition. In addition, our data indicate that energy dissipation is confined to fibers with a high cuticle-to-cortex ratio, and the amount of energy dissipated becomes more pronounced with increasing water content. The torsional properties of hair spray-treated fibers suggest that the deposited hair spray film masks the properties of the base fiber and imparts its own dissipative character to the measurement. Since tensile mechanical properties are often used to make claims about the performance of hair care products, we have compared the results obtained from torsional and tensile measurements on over-processed bleached hair fibers conditioned with Polyquaternium-10 and cetyl trimethylammonium bromide (CETAB) to evaluate which method is more advantageous. Our data demonstrate that torsional measurements can distinguish hair care products which reinforce the cuticle from those which affect the cortex, while tensile measurements showed no significant differences.
BOOK REVIEW: Seven Tales of the Pendulum Seven Tales of the Pendulum
Botet, Robert
2011-09-01
Seven Tales of the Pendulum is a kind of 'biography' of a unique physical system. We all think we know everything about the pendulum. It is indeed the elementary example in countless textbooks; it is so simple and familiar; it is such an old topic. If this is your opinion, or if you think that the movement of the pendulum is dull and boring, then you should read the book of Gregory Baker; it will come as a surprise. Inside, you will read about the various avatars of the pendulum in science, comprehending how, down the years, the complexity of the notion of pendulum behaviour developed and deepened, from regularity in classical physics to chaotic motion, and eventually to the probabilistic attitude in quantum physics. You will learn why the pendulum has often been a key element in the history of human intelligence development, and how the concept of the pendulum in science uncovered routes for novel breakthroughs. Using everything but dry mathematics, Baker uses narrative and figures well to give a vivid review of the physics of the pendulum in the general context of human culture. This is a captivating book, and you will surprise yourself when you ask, 'what will be written on the next page?'.
Torsional Ratcheting Actuating System
Energy Technology Data Exchange (ETDEWEB)
BARNES,STEPHEN MATTHEW; MILLER,SAMUEL L.; RODGERS,M. STEVEN; BITSIE,FERNANDO
2000-01-24
A new type of surface micromachined ratcheting actuation system has been developed at the Microelectronics Development Laboratory at Sandia National Laboratories. The actuator uses a torsional electrostatic comb drive that is coupled to an external ring gear through a ratcheting scheme. The actuator can be operated with a single square wave, has minimal rubbing surfaces, maximizes comb finger density, and can be used for open-loop position control. The prototypes function as intended with a minimum demonstrated operating voltage of 18V. The equations of motion are developed for the torsional electrostatic comb drive. The resonant frequency, voltage vs. displacement and force delivery characteristics are predicted and compared with the fabricated device's performance.
Stability in quadratic torsion theories
Energy Technology Data Exchange (ETDEWEB)
Vasilev, Teodor Borislavov; Cembranos, Jose A.R.; Gigante Valcarcel, Jorge; Martin-Moruno, Prado [Universidad Complutense de Madrid, Departamento de Fisica Teorica I, Madrid (Spain)
2017-11-15
We revisit the definition and some of the characteristics of quadratic theories of gravity with torsion. We start from a Lagrangian density quadratic in the curvature and torsion tensors. By assuming that General Relativity should be recovered when the torsion vanishes and investigating the behaviour of the vector and pseudo-vector torsion fields in the weak-gravity regime, we present a set of necessary conditions for the stability of these theories. Moreover, we explicitly obtain the gravitational field equations using the Palatini variational principle with the metricity condition implemented via a Lagrange multiplier. (orig.)
Stability in quadratic torsion theories
Vasilev, Teodor Borislavov; Cembranos, Jose A. R.; Valcarcel, Jorge Gigante; Martín-Moruno, Prado
2017-11-01
We revisit the definition and some of the characteristics of quadratic theories of gravity with torsion. We start from a Lagrangian density quadratic in the curvature and torsion tensors. By assuming that General Relativity should be recovered when the torsion vanishes and investigating the behaviour of the vector and pseudo-vector torsion fields in the weak-gravity regime, we present a set of necessary conditions for the stability of these theories. Moreover, we explicitly obtain the gravitational field equations using the Palatini variational principle with the metricity condition implemented via a Lagrange multiplier.
On the Dynamics of the Furuta Pendulum
Directory of Open Access Journals (Sweden)
Benjamin Seth Cazzolato
2011-01-01
Full Text Available The Furuta pendulum, or rotational inverted pendulum, is a system found in many control labs. It provides a compact yet impressive platform for control demonstrations and draws the attention of the control community as a platform for the development of nonlinear control laws. Despite the popularity of the platform, there are very few papers which employ the correct dynamics and only one that derives the full system dynamics. In this paper, the full dynamics of the Furuta pendulum are derived using two methods: a Lagrangian formulation and an iterative Newton-Euler formulation. Approximations are made to the full dynamics which converge to the more commonly presented expressions. The system dynamics are then linearised using a Jacobian. To illustrate the influence the commonly neglected inertia terms have on the system dynamics, a brief example is offered.
The order-chaos-order sequence in the spring pendulum
van der Weele, J.P.; de Kleine, Elian
1996-01-01
We study the motions of a spring pendulum as a function of its two control parameters (the ratio of the spring and pendulum frequencies, and the energy). It is shown that in the limits for very small and very large parameter values the dynamics of the spring pendulum is predominantly regular, while
Neural network model to control an experimental chaotic pendulum
Bakker, R; Schouten, JC; Takens, F; vandenBleek, CM
1996-01-01
A feedforward neural network was trained to predict the motion of an experimental, driven, and damped pendulum operating in a chaotic regime. The network learned the behavior of the pendulum from a time series of the pendulum's angle, the single measured variable. The validity of the neural
Light rays and the tidal gravitational pendulum
Farley, A. N. St J.
2018-05-01
Null geodesic deviation in classical general relativity is expressed in terms of a scalar function, defined as the invariant magnitude of the connecting vector between neighbouring light rays in a null geodesic congruence projected onto a two-dimensional screen space orthogonal to the rays, where λ is an affine parameter along the rays. We demonstrate that η satisfies a harmonic oscillator-like equation with a λ-dependent frequency, which comprises terms accounting for local matter affecting the congruence and tidal gravitational effects from distant matter or gravitational waves passing through the congruence, represented by the amplitude, of a complex Weyl driving term. Oscillating solutions for η imply the presence of conjugate or focal points along the rays. A polarisation angle, is introduced comprising the orientation of the connecting vector on the screen space and the phase, of the Weyl driving term. Interpreting β as the polarisation of a gravitational wave encountering the light rays, we consider linearly polarised waves in the first instance. A highly non-linear, second-order ordinary differential equation, (the tidal pendulum equation), is then derived, so-called due to its analogy with the equation describing a non-linear, variable-length pendulum oscillating under gravity. The variable pendulum length is represented by the connecting vector magnitude, whilst the acceleration due to gravity in the familiar pendulum formulation is effectively replaced by . A tidal torque interpretation is also developed, where the torque is expressed as a coupling between the moment of inertia of the pendulum and the tidal gravitational field. Precessional effects are briefly discussed. A solution to the tidal pendulum equation in terms of familiar gravitational lensing variables is presented. The potential emergence of chaos in general relativity is discussed in the context of circularly, elliptically or randomly polarised gravitational waves encountering the null
Pendulum motions of extended lunar space elevator
Burov, A. A.; Kosenko, I. I.
2014-09-01
In the usual everyday life, it is well known that the inverted pendulum is unstable and is ready to fall to "all four sides," to the left and to the right, forward and backward. The theoretical studies and the lunar experience of moon robots and astronauts also confirms this property. The question arises: Is this property preserved if the pendulum is "very, very long"? It turns out that the answer is negative; namely, if the pendulum length significantly exceeds the Moon radius, then the radial equilibria at which the pendulum is located along the straight line connecting the Earth and Moon centers are Lyapunov stable and the pendulum does not fall in any direction at all. Moreover, if the pendulum goes beyond the collinear libration points, then it can be extended and manufactured from cables. This property was noted by F. A. Tsander and underlies the so-called lunar space elevator (e.g., see [1]). In the plane of the Earth and Moon orbits, there are some other equilibria which turn out to be unstable. The question is, Are there equilibria at which the pendulum is located outside the orbital plane? In this paper, we show that the answer is positive, but such equilibria are unstable in the secular sense. We also study necessary conditions for the stability of lunar pendulum oscillations in the plane of the lunar orbit. It was numerically discovered that stable and unstable equilibria alternate depending on the oscillation amplitude and the angular velocity of rotation. The study of the lunar elevator dynamics originates in [2]. The concept of lunar elevator was developed in detail in [3, 4]. Several classes of equilibria with the finiteness of the Moon size taken into account were studied in [5]. The possibility of location of an orbital station fixed to the Moon surface by a pair of tethers was investigated in [6]. The problem of orientation of the terminal station of the lunar space elevator was studied in [7]. The influence of the tether length variations on the
Torsional Rigidity of Minimal Submanifolds
DEFF Research Database (Denmark)
Markvorsen, Steen; Palmer, Vicente
2006-01-01
We prove explicit upper bounds for the torsional rigidity of extrinsic domains of minimal submanifolds $P^m$ in ambient Riemannian manifolds $N^n$ with a pole $p$. The upper bounds are given in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped...
Figuring the Acceleration of the Simple Pendulum
Lieberherr, Martin
2011-01-01
The centripetal acceleration has been known since Huygens' (1659) and Newton's (1684) time. The physics to calculate the acceleration of a simple pendulum has been around for more than 300 years, and a fairly complete treatise has been given by C. Schwarz in this journal. But sentences like "the acceleration is always directed towards the…
Practical Applications of the Compound Pendulum.
Hinrichsen, Peter F.
1981-01-01
Examples of the application of compound pendulum theory to the practical measurement of the moments of inertia of human beings, farm tractors, and sailing boats are presented. Suggests developing laboratory experiments to measure moments of inertia of hockey sticks, golf clubs, and frisbees, among others. (Author/SK)
Ovarian torsion: Echographic discoveries
International Nuclear Information System (INIS)
Triana R, Gustavo; Navas O, Claudia
1994-01-01
Patient of 31 years who consulted to the even service of urgencies to present of two hours of evolution intense pain in flank and region lumbar left, associated to vomit, present square similar 5 previous days to the entrance in the right side. Go Po, plans with DIU FUR, 8 previous days to the square. It is practiced Tran abdominal pelvic echography that shows left ovary of 6 x 5 x 3 cms, with multiple follicular images, of thick walls, with I liquidate free abdominal, highly suggestive of ovarian torsion although the patient didn't present square of sharp abdomen. It decides to suspend analgesic and to value it, presented sharp abdominal pain, reason why laparotomy was practiced, finding mass of 6 x 6 cms. of necrotic aspect, corresponding to the left ovary, which presented three turns on their axis. It is taken finish left salpingooferectomy
DEFF Research Database (Denmark)
Hyttel, Trine E W; Bak, Geske S; Larsen, Solveig B
2015-01-01
The increasing use of de-torsion of the ovaries may result in re-torsion. This review addresses risk of re-torsion and describes preventive strategies to avoid re-torsion in pre-menarcheal girls, and fertile and pregnant women. We clinically reviewed PubMed, Embase, Trip and Cochrane databases...
Spin and torsion in gravitation
De Sabbata, Venzo
1994-01-01
This book gives an exposition of both the old and new results of spin and torsion effects on gravitational interactions with implications for particle physics, cosmology etc. Physical aspects are stressed and measurable effects in relation to other areas of physics are discussed.Among the topics discussed are: alternative ways of unifying gravity with electroweak and strong interactions by an energy dependent spin torsion coupling constant; the idea that all interactions can be understood as originating from spin curvature coupling; the possibility of cosmological models with torsion providing
DEFF Research Database (Denmark)
Hansen, Klavs Feilberg; Pedersen, Carsten Mørk
2008-01-01
be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....
Constraining spacetime torsion with LAGEOS
March, Riccardo; Bellettini, Giovanni; Tauraso, Roberto; Dell'Agnello, Simone
2011-11-01
We compute the corrections to the orbital Lense-Thirring effect (or frame-dragging) in the presence of spacetime torsion. We analyze the motion of a test body in the gravitational field of a rotating axisymmetric massive body, using the parametrized framework of Mao, Tegmark, Guth and Cabi. In the cases of autoparallel and extremal trajectories, we derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of Celestial Mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter. We also show how the LAser GEOdynamics Satellites (LAGEOS) can be used to constrain torsion parameters. We report the experimental constraints obtained using both the nodes and perigee measurements of the orbital Lense-Thirring effect. This makes LAGEOS and Gravity Probe B complementary frame-dragging and torsion experiments, since they constrain three different combinations of torsion parameters.
Advanced Control of Wheeled Inverted Pendulum Systems
Li, Zhijun; Fan, Liping
2013-01-01
Advanced Control of Wheeled Inverted Pendulum Systems is an orderly presentation of recent ideas for overcoming the complications inherent in the control of wheeled inverted pendulum (WIP) systems, in the presence of uncertain dynamics, nonholonomic kinematic constraints as well as underactuated configurations. The text leads the reader in a theoretical exploration of problems in kinematics，dynamics modeling, advanced control design techniques,and trajectory generation for WIPs. An important concern is how to deal with various uncertainties associated with the nominal model, WIPs being characterized by unstable balance and unmodelled dynamics and being subject to time-varying external disturbances for which accurate models are hard to come by. The book is self-contained, supplying the reader with everything from mathematical preliminaries and the basic Lagrange-Euler-based derivation of dynamics equations to various advanced motion control and force control approaches as well as trajectory generation met...
Strange mechanics of the neutrino flavor pendulum
Johns, Lucas; Fuller, George M.
2018-01-01
We identify in the flavor transformation of astrophysical neutrinos a new class of phenomena, a common outcome of which is the suppression of flavor conversion. Appealing to the equivalence between a bipolar neutrino system and a gyroscopic pendulum, we find that these phenomena have rather striking interpretations in the mechanical picture: in one instance, the gyroscopic pendulum initially precesses in one direction, then comes to a halt and begins to precess in the opposite direction—a counterintuitive behavior that we analogize to the motion of a toy known as a rattleback. We analyze these behaviors in the early Universe, wherein a chance connection to sterile neutrino dark matter emerges, and we briefly suggest how they might manifest in compact-object environments.
Interactive Internet Based Pendulum for Learning Mechatronics
Sethson, Magnus R.
2003-01-01
This paper describes an Internet based remote experimental setup of a double lined pendulum mechanism for students experiments at the M. Sc. Level. Some of the first year experience using this web-based setup in classes is referred. In most of the courses given at the division of mechanical engineering systems at Linkoeping Institute of Technology we provide experimental setups to enhance the teaching Of M.Sc. students. Many of these experimental setups involve mechatronical systems. Disciplines like fluid power, electronics, and mechanics and also software technologies are used in each experiment. As our campus has recently been split into two different cities some new concepts for distance learning have been studied. The one described here tries to implement remotely controlled mechatronic setups for teaching basic programming of real-time operating systems and analysis of the dynamics of mechanical systems. The students control the regulators for the pendulum through a web interface and get measurement results and a movie back through their email. The present setup uses a double linked pendulum that is controlled by a DC-motor and monitored through both camera and angular position sensors. All software needed is hosted on a double-processor PC running the RedHat 7.1. distribution complemented with real-time scheduling using DIAPM-RTAI 1.7. The Internet site is presented to the students using PHP, Apache and MySQL. All of the used software originates from the open source domain. The experience from integrating these technologies and security issues is discussed together with the web-camera interface. One of the important experiences from this project so far is the need for a good visual feedback. This is both in terms of video speed but also in resolution. It has been noticed that when the students makes misstates and wants to search the failure they want clear, large images with high resolution to support their personal believes in the cause of the failure. Even
Active damping of self-excited torsional vibrations in oil well drillstrings
Jansen, J. D.; van den Steen, L.
1995-01-01
A drillstring used for the drilling of oil or gas wells behaves as a rotating torsional pendulum. The drillstring is rotated at a constant angular velocity by an electric motor, but exhibits superimposed torsional vibrations caused by a non-linear relationship between torque and angular velocity at the rock-crushing tool. The vibrations are self-excited, and disappear when the mean angular velocity of the pendulum is raised above a threshold value. An active damping system is described that strongly reduces the threshold value by using feedback control, thus extending the working range for vibration-free rotation. It operates at the current and the voltage of the electric motor, and can be implemented with only electrical components. The active damping system is interpreted as an extension of the passive tuned vibration absorber for quenching of self-excited vibrations in the form of a resilient foundation, as described by Tondl (1975 Journal of Sound and Vibration42(2), 251-260). The concept of quenching self-excited vibrations by modifying the drive system as described in this paper is directly applicable to other engineering systems which are driven by a separately excited DC motor. Furthermore, the concept can be applied to systems driven by a hydraulic motor with a continuously variable flow rate.
Torsional Phacoemulsification and Tip Selection
Directory of Open Access Journals (Sweden)
Fırat Helvacıoğlu
2014-10-01
Full Text Available One of the recent advances in cataract surgery is torsional phacoemulsification. It was developed to increase the efficacy of ultrasonic emulsification. In torsional phacoemulsification, the torsional movement of the tip is translated to side-to-side cutting action with the aid of bent phaco tips. Lens material is cut in both directions, rather than only during a forward stroke. The efficiency of this technique is further enhanced by an improvement in followability provided by the inherent non-repulsive nature of the side-to-side motion. Tip selection is very important for the efficiency of torsional phacoemulsification. Theoretically, there are 2 ways to enhance the cutting efficiency of the tip. First is the stroke length; the 22-degree bent 30-degree Kelman mini-flared tip cuts longer than the 12-degree bent 30-degree mini-flared Kelman tip. Second is the angulation or bevel; the higher the degree (45 degrees, the better cutting efficiency. Retrospective analyses of the previously published clinical studies clearly demonstrated that the efficacy of the torsional phacoemulsification has positive correlation with both the aperture angles and neck angles of the tips. (Turk J Ophthalmol 2014; 44: 392-5
A Laboratory Experiment on Coupled Non-Identical Pendulums
Li, Ang; Zeng, Jingyi; Yang, Hujiang; Xiao, Jinghua
2011-01-01
In this paper, coupled pendulums with different lengths are studied. Through steel magnets, each pendulum is coupled with others, and a stepping motor is used to drive the whole system. To record the data automatically, we designed a data acquisition system with a CCD camera connected to a computer. The coupled system shows in-phase, locked-phase…
Demonstrating the physics of simple pendulum via computer ...
African Journals Online (AJOL)
This paper investigates how one can teach 'the physics of simple pendulum in the classroom by means of computer simulation, Employing the fourth order Runge-Kutta method carries out the simulation. It is believed that the simulation helps students to understand the physics of simple pendulum easily The simulation ...
Tissue Friendly Pendulum: Soft Liner to prevent Tissue Irritation
Directory of Open Access Journals (Sweden)
Siddharth Shashidhar Revankar
2014-01-01
Full Text Available Palatal mucosal irritation is commonly encountered with the Pendulum appliance. The efficiency of soft liners in reducing tissue irritation has been well documented in the field of prosthodontics. The following article describes an innovative technique where soft liner can be used to reduce palatal mucosal irritation caused by pendulum appliance.
Steady States of the Parametric Rotator and Pendulum
Bouzas, Antonio O.
2010-01-01
We discuss several steady-state rotation and oscillation modes of the planar parametric rotator and pendulum with damping. We consider a general elliptic trajectory of the suspension point for both rotator and pendulum, for the latter at an arbitrary angle with gravity, with linear and circular trajectories as particular cases. We treat the…
Effect of the spherical Earth on a simple pendulum
Burko, Lior M.
2003-01-01
We consider the period of a simple pendulum in the gravitational field of the spherical Earth. Effectively, gravity is enhanced compared with the often used flat Earth approximation, such that the period of the pendulum is shortened. We discuss the flat Earth approximation, and show when the corrections due to the spherical Earth may be of interest.
The Pit and the Safety Pendulum
Energy Technology Data Exchange (ETDEWEB)
Nitschke, Robert Leon; Ramos, Amadeo Gabriel
2000-11-01
The hypothesis of this paper is that the safety analysis pendulum has swung considerably in the direction of increasingly complex and lengthy safety evaluations and intense reviews during the past 30 years. The test of this hypothesis will be a review of the safety analysis conducted for various activities associated with the retrieval of transuranic radioactive waste from burial pits at a National Laboratory site over a span of 30 years. The examination will focus on the safety aspects and the safety analysis that was conducted for the projects. At the conclusion of this examination, the paper will identify five reasons why the changes have taken place.
Study of Inverted Pendulum Robot Using Fuzzy Servo Control Method
Directory of Open Access Journals (Sweden)
Dazhong Wang
2012-09-01
Full Text Available The inverted pendulum robot is a classical problem in controls. The inherit instabilities in the setup make it a natural target for a control system. Inverted pendulum robot is suitable to use for investigation and verification of various control methods for dynamic systems. Maintaining an equilibrium position of the pendulum pointing up is a challenge as this equilibrium position is unstable. As the inverted pendulum robot system is nonlinear it is well-suited to be controlled by fuzzy logic. In this paper, Lagrange method has been applied to develop the mathematical model of the system. The objective of the simulation to be shown using the fuzzy control method can stabilize the nonlinear system of inverted pendulum robot.
Dirac operators and Killing spinors with torsion
International Nuclear Information System (INIS)
Becker-Bender, Julia
2012-01-01
On a Riemannian spin manifold with parallel skew torsion, we use the twistor operator to obtain an eigenvalue estimate for the Dirac operator with torsion. We consider the equality case in dimensions four and six. In odd dimensions we describe Sasaki manifolds on which equality in the estimate is realized by Killing spinors with torsion. In dimension five we characterize all Killing spinors with torsion and obtain certain naturally reductive spaces as exceptional cases.
Otsuka, Hisanori; Hattori, Masahiro
When the structures, for example arch bridges are subjected bending moments and torsional moments, the strength and rigidity of the members decline compared to those of pure bending or torsion load condition. However, any analysis soft don't consider interrelation between bending and torsion ,and effects of torsional moments have not been considered severely in seismic design. In this study, the authors proposed analysis technique considering interaction between bending and torsion to estimate torsional moments severely, and formulized the analysis tools for this technique. These are interaction curve, skeleton for combined load, hysteresis for torsion. Moreover, the authors analyzed a RC arch bridge using this method, and inspected the validity of comparing the results obtained equivalent linear analysis about torsion and nonlinear torsional analysis not considering the interaction between bending and torsion.
Painless Ovarian Torsion Mimicking a Uterine Myoma
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Cheng-Kuo Lin
2006-12-01
Conclusion: Ovarian torsion is a significant cause of acute lower abdominal pain in women and is a gynecologic surgical emergency. Nevertheless, surgical strategies are usually impeded because of ambiguous warning signs. Clinicians may be misled by certain conditions such as silent ovarian torsion. Although there may be no specific indication, the diagnosis of ovarian torsion should be considered on finding a pelvic mass.
The odd side of torsion geometry
DEFF Research Database (Denmark)
Conti, Diego; Madsen, Thomas Bruun
2012-01-01
We introduce and study a notion of `Sasaki with torsion structure' (ST) as an odd-dimensional analogue of Kähler with torsion geometry (KT). These are normal almost contact metric manifolds that admit a unique compatible connection with 3-form torsion. Any odd-dimensional compact Lie group is sho...
Nonlinear dynamics of a rotating double pendulum
Energy Technology Data Exchange (ETDEWEB)
Maiti, Soumyabrata, E-mail: ayanmaiti19@gmail.com [Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, 711103 (India); Roy, Jyotirmoy, E-mail: jyotirmoy.roy@live.com [UM-DAE Centre for Excellence in Basic Sciences, Santa Cruz, Mumbai, 400098 (India); Mallik, Asok K., E-mail: asokiitk@gmail.com [Department of Applied Mechanics and Aerospace Engineering, Indian Institute of Engineering Science and Technology, Shibpur, 711103 (India); Bhattacharjee, Jayanta K., E-mail: jayanta.bhattacharjee@gmail.com [Harish-Chandra Research Institute, Allahabad, 211019 (India)
2016-01-28
Nonlinear dynamics of a double pendulum rotating at a constant speed about a vertical axis passing through the top hinge is investigated. Transitions of oscillations from chaotic to quasiperiodic and back to chaotic again are observed with increasing speed of rotation. With increasing speed, a pair of new stable equilibrium states, different from the normal vertical one, appear and the quasiperiodic oscillations occur. These oscillations are first centered around the origin, but with increasing rotation speed they cover the origin and the new fixed points. At a still higher speed, more than one pair of fixed points appear and the oscillation again turns chaotic. The onset of chaos is explained in terms of internal resonance. Analytical and numerical results confirm the critical values of the speed parameter at various transitions. - Highlights: • The rotating double pendulum shows transitions from chaos to order and back to chaos. • These transitions occur as the rotation speed is increased. • The dynamics is quasi-periodic in the ordered state. • Within the ordered state the nature of quasi-periodicity changes with rotation speed. • The chaotic state always emerges as a result of an internal resonance.
Pendulum mass affects the measurement of articular friction coefficient.
Akelman, Matthew R; Teeple, Erin; Machan, Jason T; Crisco, Joseph J; Jay, Gregory D; Fleming, Braden C
2013-02-01
Friction measurements of articular cartilage are important to determine the relative tribologic contributions made by synovial fluid or cartilage, and to assess the efficacy of therapies for preventing the development of post-traumatic osteoarthritis. Stanton's equation is the most frequently used formula for estimating the whole joint friction coefficient (μ) of an articular pendulum, and assumes pendulum energy loss through a mass-independent mechanism. This study examines if articular pendulum energy loss is indeed mass independent, and compares Stanton's model to an alternative model, which incorporates viscous damping, for calculating μ. Ten loads (25-100% body weight) were applied in a random order to an articular pendulum using the knees of adult male Hartley guinea pigs (n=4) as the fulcrum. Motion of the decaying pendulum was recorded and μ was estimated using two models: Stanton's equation, and an exponential decay function incorporating a viscous damping coefficient. μ estimates decreased as mass increased for both models. Exponential decay model fit error values were 82% less than the Stanton model. These results indicate that μ decreases with increasing mass, and that an exponential decay model provides a better fit for articular pendulum data at all mass values. In conclusion, inter-study comparisons of articular pendulum μ values should not be made without recognizing the loads used, as μ values are mass dependent. Copyright © 2012 Elsevier Ltd. All rights reserved.
Novel Spherical Robot with Hybrid Pendulum Driving Mechanism
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Sung-Su Ahn
2014-11-01
Full Text Available As regards omnidirectional driving, conventional one- and two-pendulum spherical robots have a limited capability due to a limited pendulum motion range. In particular, such robots cannot move from a stationary state in a parallel direction to the center horizontal axis to which the pendulums are attached. Thus, to overcome the limited driving capability of one- and two-pendulum driven spherical robots, a passive version of a spherical robot, called KisBot II, was developed with a curved two-pendulum driving mechanism operated by a joystick. However, this paper presents an active upgraded version of KisBot II that includes a DSP-based control system and Task-based software architecture for driving control and data communication, respectively. A dynamic model for two-pendulum driving is derived using the Lagrange equation method, and a feedback controller for linear driving using two pendulums is then constructed based on the dynamic model. Experiments with several motions verify the driving efficiency of the proposed novel spherical robot.
Note: A 1-m Foucault pendulum rolling on a ball
Salva, H. R.; Benavides, R. E.; Venturino, J. A.; Cuscueta, D. J.; Ghilarducci, A. A.
2013-10-01
We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.
Parametric resonance induced chaos in magnetic damped driven pendulum
Energy Technology Data Exchange (ETDEWEB)
Khomeriki, Giorgi, E-mail: giokhomeriki123@gmail.com
2016-07-15
A damped driven pendulum with a magnetic driving force, appearing from a solenoid, where ac current flows is considered. The solenoid acts on the magnet, which is located at a free end of the pendulum. In this system the existence and interrelation of chaos and parametric resonance is theoretically examined. Derived analytical results are supported by numerical simulations and conducted experiments. - Highlights: • A damped magnetic pendulum is considered driven by off resonant magnetic field. • Our system is chaotic only when the conditions for parametric resonance are fulfilled. • Conducted experiments give a good agreement with theory and numerical simulations. • Calculated Lyapunov exponents are compared with parametric instability growth rates.
Note: A 1-m Foucault pendulum rolling on a ball.
Salva, H R; Benavides, R E; Venturino, J A; Cuscueta, D J; Ghilarducci, A A
2013-10-01
We have built a short Foucault pendulum of 1-m length. The aim of this work was to increase the sensitivity to elliptical trajectories from other longer pendula. The design was a semi-rigid pendulum that rolls over a small ball. The measurements of the movements (azimuth and elliptical trajectory) were done by an optical method. The resulting pendulum works in a medium satisfactory way due to problems of the correct choice of the mass of the bob together with the diameter of the supporting ball. It is also important to keep the rolling surface very clean.
TORSION OF THE VERMIFORM APPENDIX: A CASE REPORT
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Dr. Imtiaz Wani
2009-07-01
Full Text Available Torsion of the vermiform appendix is a rare condition with few cases reported in the literature. Various factors predispose to torsion. Various factors predispose to torsion. We report a case of primary torsion of the vermiform appendix. The clinical presentation was indistinguishable from acute appendicitis and the diagnosis was made at operation. Appendix was preileal in position and the direction of torsion was anticlockwise. There was intrinsic torsion with no obvious factor for torsion identified. Appendectomy was performed.
Seismic shear waves as Foucault pendulum
Snieder, Roel; Sens-Schönfelder, Christoph; Ruigrok, Elmer; Shiomi, Katsuhiko
2016-03-01
Earth's rotation causes splitting of normal modes. Wave fronts and rays are, however, not affected by Earth's rotation, as we show theoretically and with observations made with USArray. We derive that the Coriolis force causes a small transverse component for P waves and a small longitudinal component for S waves. More importantly, Earth's rotation leads to a slow rotation of the transverse polarization of S waves; during the propagation of S waves the particle motion behaves just like a Foucault pendulum. The polarization plane of shear waves counteracts Earth's rotation and rotates clockwise in the Northern Hemisphere. The rotation rate is independent of the wave frequency and is purely geometric, like the Berry phase. Using the polarization of ScS and ScS2 waves, we show that the Foucault-like rotation of the S wave polarization can be observed. This can affect the determination of source mechanisms and the interpretation of observed SKS splitting.
The double pendulum: a numerical study
Calvão, A. M.; Penna, T. J. P.
2015-07-01
Analysis and characterization of dynamical systems is a common task in computational physics. It frequently demands new algorithms for finding solutions and new techniques for analysing the results. Here we review some of these algorithms and techniques in the study of the double pendulum, which, despite being a very simple mechanical system, can display complex behaviour. Even though it has been studied before (Yu and Bi 1998 J. Sound Vib. 217 691736; Stachowiak and Okada 2006 Chaos, Solitons & Fractals 29 417422; Rafat, Wheatland and Bedding 2009 Am. J. Phys. 77 216-23; Levien and Tan 1993 Am. J. Phys. 61 103844), here we present a deeper discussion of the several methods and algorithms that are used in typical studies of dynamical systems. In addition, we present new results obtained through techniques commonly used in the analysis of complex systems.
KONTROL TRACKING FUZZY MENGGUNAKAN MODEL FOLLOWING UNTUK SISTEM PENDULUM KERETA
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Jimmy Hennyta Satya Putra
2017-01-01
Full Text Available Sistem pendulum kereta memiliki karakteristik yang tidak stabil dan nonlinear. Pada Tugas Akhir ini membahas tentang kontrol tracking dengan menggunakan struktur kontrol berbasis model following. Permasalahan dalam desain struktur kontrol tracking pada sistem pendulum kereta ini adalah bagaimana membuat posisi kereta dapat mengikuti sinyal referensi dengan tetap mempertahankan batang pendulum pada posisi equilibriumnya yaitu pada sudut nol radian. Model nonlinear dari sistem pendulum kereta direpresentasikan sebagai model fuzzy Takagi-Sugeno. Berdasarkan model tersebut, aturan kontroler disusun menggunakan konsep Parallel Distributed Compensation (PDC berbasis teknik kontrol optimal. Hasil simulasi dan implementasi menunjukkan bahwa posisi kereta dapat mengikuti sinyal referensi tanpa adanya beda fasa antara respon posisi kereta terhadap sinyal referensi. Sinyal referensi sinus memberikan performansi tracking terbaik, dengan Integral Absolute Error (IAE terkecil diantara sinyal referensi lain, yaitu pada simulasi sebesar 0,2622 dan pada implementasi sebesar 0,8477
Torsions of 3-dimensional manifolds
Wurzbacher, T
2002-01-01
From the reviews: "This is an excellent exposition about abelian Reidemeister torsions for three-manifolds." ―Zentralblatt Math "This monograph contains a wealth of information many topologists will find very handy. …Many of the new points of view pioneered by Turaev are gradually becoming mainstream and are spreading beyond the pure topology world. This monograph is a timely and very useful addition to the scientific literature." ―Mathematical Reviews
Moduli space of torsional manifolds
International Nuclear Information System (INIS)
Becker, Melanie; Tseng, L.-S.; Yau, S.-T.
2007-01-01
We characterize the geometric moduli of non-Kaehler manifolds with torsion. Heterotic supersymmetric flux compactifications require that the six-dimensional internal manifold be balanced, the gauge bundle be Hermitian Yang-Mills, and also the anomaly cancellation be satisfied. We perform the linearized variation of these constraints to derive the defining equations for the local moduli. We explicitly determine the metric deformations of the smooth flux solution corresponding to a torus bundle over K3
Torsional resistance of retreatment instruments.
Lopes, Hélio P; Elias, Carlos N; Vedovello, Gislaine A F; Bueno, Carlos E S; Mangelli, Marcelo; Siqueira, José F
2011-10-01
This study compared the torsional resistance of two brands of rotary nickel-titanium (NiTi) instruments indicated for endodontic retreatment. Mtwo retreatment instruments #15 and #25 (VDW, Munich, Germany) and ProTaper Universal retreatment instruments D2 and D3 (Maillefer/Dentsply, Ballaigues, Switzerland) were subjected to a torsional assay in clockwise rotation. The two parameters evaluated were maximum torque and angular deflection at failure. Fractured instruments had their fractured surfaces and helical shafts examined by scanning electron microscopy. The results indicated that the angular deflection at fracture decreased in the following order: Mtwo retreatment file #15 > Mtwo retreatment file #25 > ProTaper Universal retreatment file D2 > ProTaper Universal retreatment file D3. As for the maximum torque values, the results revealed the following descending order: ProTaper Universal file D2 > Mtwo retreatment file #25 > ProTaper Universal file D3 > Mtwo retreatment file #15. Scanning electron microscopic analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments. Fractured surfaces were of the ductile type. The instruments tested showed different torsional behavior depending on the parameter evaluated. If one considers that high angular deflection values may serve as a safety factor, then the Mtwo retreatment instruments showed significantly better results. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
Radial forcing and Edgar Allan Poe's lengthening pendulum
McMillan, Matthew; Blasing, David; Whitney, Heather M.
2013-09-01
Inspired by Edgar Allan Poe's The Pit and the Pendulum, we investigate a radially driven, lengthening pendulum. We first show that increasing the length of an undriven pendulum at a uniform rate does not amplify the oscillations in a manner consistent with the behavior of the scythe in Poe's story. We discuss parametric amplification and the transfer of energy (through the parameter of the pendulum's length) to the oscillating part of the system. In this manner, radial driving can easily and intuitively be understood, and the fundamental concept applied in many other areas. We propose and show by a numerical model that appropriately timed radial forcing can increase the oscillation amplitude in a manner consistent with Poe's story. Our analysis contributes a computational exploration of the complex harmonic motion that can result from radially driving a pendulum and sheds light on a mechanism by which oscillations can be amplified parametrically. These insights should prove especially valuable in the undergraduate physics classroom, where investigations into pendulums and oscillations are commonplace.
Newton-Cartan gravity and torsion
Bergshoeff, Eric; Chatzistavrakidis, Athanasios; Romano, Luca; Rosseel, Jan
2017-10-01
We compare the gauging of the Bargmann algebra, for the case of arbitrary torsion, with the result that one obtains from a null-reduction of General Relativity. Whereas the two procedures lead to the same result for Newton-Cartan geometry with arbitrary torsion, the null-reduction of the Einstein equations necessarily leads to Newton-Cartan gravity with zero torsion. We show, for three space-time dimensions, how Newton-Cartan gravity with arbitrary torsion can be obtained by starting from a Schrödinger field theory with dynamical exponent z = 2 for a complex compensating scalar and next coupling this field theory to a z = 2 Schrödinger geometry with arbitrary torsion. The latter theory can be obtained from either a gauging of the Schrödinger algebra, for arbitrary torsion, or from a null-reduction of conformal gravity.
Using torsion to manipulate spin currents
Fumeron, Sébastien; Berche, Bertrand; Medina, Ernesto; Santos, Fernando A. N.; Moraes, Fernando
2017-02-01
We address the problem of quantum particles moving on a manifold characterised by the presence of torsion along a preferential axis. In fact, such a torsion may be taylored by the presence of a single screw dislocation, whose Burgers vector measures the torsion amplitude. The problem, first treated in the relativistic limit describing fermions that couple minimally to torsion, is then analysed in the Pauli limit. We show that torsion induces a geometric potential and also that it couples generically to the phase of the wave function, giving rise to the possibility of using torsion to manipulate spin currents in the case of spinor wave functions. These results emerge as an alternative strategy for using screw dislocations in the design of spintronic-based devices.
Quantum General Relativity, Torsion and Uncertainty Relations
de Sabbata, V.; Sivaram, C.; Borzeszkowski, H.-H. V.; Treder, H.-J.
It is shown that in gravitational theories with torsion one is led to commutation rules corresponding to Landau-Peierls type uncertainty relations.Translated AbstractQuantisierte allgemeine Relativitätstheorie, Torsion und UnschärferelationenEs wird gezeigt, daß man in Gravitationstheorien mit Torsion zu Vertauschungsregeln geführt wird, die Landau-Peierls-artigen Unschärferelationen entsprechen.
Tibial Torsion Among Filipinos: A Cadaveric Study
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Villamin CAC
2012-07-01
Full Text Available Tibial torsion, the twisting of the tibia about its long axis, can affect rotational positioning in total knee replacement. This angle varies depending on the ethnicity of the subject. There are no published studies to date to determine the tibial torsion among Filipinos. In this study, 28 cadaveric limbs were examined. Our results show that the average tibial torsion among adult Filipinos is 28.9°.
Dirac operators and Killing spinors with torsion; Dirac-Operatoren und Killing-Spinoren mit Torsion
Energy Technology Data Exchange (ETDEWEB)
Becker-Bender, Julia
2012-12-17
On a Riemannian spin manifold with parallel skew torsion, we use the twistor operator to obtain an eigenvalue estimate for the Dirac operator with torsion. We consider the equality case in dimensions four and six. In odd dimensions we describe Sasaki manifolds on which equality in the estimate is realized by Killing spinors with torsion. In dimension five we characterize all Killing spinors with torsion and obtain certain naturally reductive spaces as exceptional cases.
Ultimate Strength of Ship Hulls under Torsion
DEFF Research Database (Denmark)
Paik, Jeom Kee; Thayamballi, Anil K.; Pedersen, Preben Terndrup
2001-01-01
subjected to torsion. A procedure for calculating these stresses is briefly described. As an illustrative example, the distribution and magnitude of warping and shear stresses for a typical container vessel hull cross section under unit torsion is calculated by the procedure. By theoretical and numerical...... analyses, it is shown that the influence of torsion induced warping stresses on the ultimate hull girder bending strength is small for ductile hull materials while torsion induced shear stresses will of course reduce the ship hull ultimate bending moment....
Primary splenic torsion in a Boston terrier
International Nuclear Information System (INIS)
Ohta, H.; Takagi, S.; Murakami, M.; Sasaki, N.; Yoshikawa, M.; Nakamura, K.; Hwang, S.J.; Yamasaki, M.; Takiguchi, M.
2009-01-01
A 7-year-old female Boston terrier was referred to Hokkaido University Veterinary Teaching Hospital with a history of hemoglobinuria and anemia for several days. Abdominal radiographs showed splenomegaly, and ultrasonography revealed a hypoechoic splenic parenchyma with interspersed linear echoes consistent with the ultrasonographic appearance of splenic torsion. Ultrasonography and computed tomography (CT) indicated a C-shaped spleen. Exploratory laparotomy confirmed the diagnosis of splenic torsion. A splenectomy was performed, and the dog recovered well without complications. This is the first report of splenic torsion in Boston terriers, and the usefulness of ultrasonographic and CT findings of the splenic torsion was also confirmed
Primary splenic torsion in a Boston terrier.
OHTA, Hiroshi; TAKAGI, Satoshi; MURAKAMI, Masahiro; SASAKI, Noboru; YOSHIKAWA, Muneyoshi; NAKAMURA, Kensuke; HWANG, Shiang-Jyi; YAMASAKI, Masahiro; TAKIGUCHI, Mitsuyoshi
2009-11-01
A 7-year-old female Boston terrier was referred to Hokkaido University Veterinary Teaching Hospital with a history of hemoglobinuria and anemia for several days. Abdominal radiographs showed splenomegaly, and ultrasonography revealed a hypoechoic splenic parenchyma with interspersed linear echoes consistent with the ultrasonographic appearance of splenic torsion. Ultrasonography and computed tomography (CT) indicated a C-shaped spleen. Exploratory laparotomy confirmed the diagnosis of splenic torsion. A splenectomy was performed, and the dog recovered well without complications. This is the first report of splenic torsion in Boston terriers, and the usefulness of ultrasonographic and CT findings of the splenic torsion was also confirmed.
Morphological evolution of spiders predicted by pendulum mechanics.
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Jordi Moya-Laraño
Full Text Available BACKGROUND: Animals have been hypothesized to benefit from pendulum mechanics during suspensory locomotion, in which the potential energy of gravity is converted into kinetic energy according to the energy-conservation principle. However, no convincing evidence has been found so far. Demonstrating that morphological evolution follows pendulum mechanics is important from a biomechanical point of view because during suspensory locomotion some morphological traits could be decoupled from gravity, thus allowing independent adaptive morphological evolution of these two traits when compared to animals that move standing on their legs; i.e., as inverted pendulums. If the evolution of body shape matches simple pendulum mechanics, animals that move suspending their bodies should evolve relatively longer legs which must confer high moving capabilities. METHODOLOGY/PRINCIPAL FINDINGS: We tested this hypothesis in spiders, a group of diverse terrestrial generalist predators in which suspensory locomotion has been lost and gained a few times independently during their evolutionary history. In spiders that hang upside-down from their webs, their legs have evolved disproportionately longer relative to their body sizes when compared to spiders that move standing on their legs. In addition, we show how disproportionately longer legs allow spiders to run faster during suspensory locomotion and how these same spiders run at a slower speed on the ground (i.e., as inverted pendulums. Finally, when suspensory spiders are induced to run on the ground, there is a clear trend in which larger suspensory spiders tend to run much more slowly than similar-size spiders that normally move as inverted pendulums (i.e., wandering spiders. CONCLUSIONS/SIGNIFICANCE: Several lines of evidence support the hypothesis that spiders have evolved according to the predictions of pendulum mechanics. These findings have potentially important ecological and evolutionary implications since
The pulse tube and the pendulum.
Swift, G W; Backhaus, S
2009-11-01
An inverted pulse tube in which gravity-driven convection is suppressed by acoustic oscillations is analogous to an inverted pendulum that is stabilized by high-frequency vibration of its pivot point. Gravity acts on the gas density gradient arising from the end-to-end temperature gradient in the pulse tube, exerting a force proportional to that density gradient, tending to cause convection when the pulse tube is inverted. Meanwhile, a nonlinear effect exerts an opposing force proportional to the square of any part of the density gradient that is not parallel to the oscillation direction. Experiments show that convection is suppressed when the pulse-tube convection number N(ptc)=omega(2)a(2)DeltaT/T(avg)/[g(alphaD sin theta-L cos theta)] is greater than 1 in slender tubes, where omega is the radian frequency of the oscillations, a is their amplitude, DeltaT is the end-to-end temperature difference, T(avg) is the average absolute temperature, g is the acceleration of gravity, L is the length of the pulse tube and D is its diameter, alpha is about 1.5, and the tip angle theta ranges from 90 degrees for a horizontal tube to 180 degrees for an inverted tube. Theory suggests that the temperature dependence should be DeltaT/T(avg) instead of DeltaT/T(avg).
Simultaneous acute appendicitis with right testicular torsion
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Tanveer Akhtar
2012-01-01
Full Text Available We present a child with both acute appendicitis and torsion of the right testis presenting at the same time. Testicular torsion possibly occurring due to vomiting in acute appendicitis so far has not been reported in the literature.
Teenage testicular torsion. | Onuigbo | International Journal of ...
African Journals Online (AJOL)
Aim: To study testicular torsion in teenagers in the Igbo community. Method: A retrospective study was carried out as regards requests for pathological examination of specimens received at a Regional Reference Laboratory based in Enugu. Results: Over a period of 30 years, 28 surgical specimens of testicular torsion in ...
Misdiagnosed Adult Testicular Torsion: Case Report | Ndaguatha ...
African Journals Online (AJOL)
Adult testicular torsion is thought to be rare if not relatively unusual. The rarity could be an underestimation since there are many episodes of missed torsions and misdiagnosis with other conditions of acute scrotum despite the now widespread ultra sound availability that are being reported in the literature. Such a ...
Appendicular Torsion | Dubhashi | Nigerian Journal of Surgery
African Journals Online (AJOL)
. It can be primary or secondary. This is a case report of 52-year-old female with 180° anti-clockwise rotation of the appendix. Torsion can further leads to strangulation and infarction of the organ. Appendicular torsion could be included in the ...
Remote Control of an Inverted Pendulum System for Intelligent Control Education
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Seul Jung
2011-08-01
Full Text Available This paper presents a remote control task of an inverted pendulum system for intelligent control education. The inverted pendulum moving on the guided rail is required to maintain balancing while it follows the desired trajectory commanded remotely by a joystick operated by a user. Position commands for the inverted pendulum system are given by a joystick through the network. The inverted pendulum system is controlled by a neural network control method. The corresponding control results are confirmed through experimental studies.
Precise asymptotic behavior of solutions to damped simple pendulum equations
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Tetsutaro Shibata
2009-11-01
Full Text Available We consider the simple pendulum equation $$displaylines{ -u''(t + epsilon f(u'(t = lambdasin u(t, quad t in I:=(-1, 1,cr u(t > 0, quad t in I, quad u(pm 1 = 0, }$$ where $0 < epsilon le 1$, $lambda > 0$, and the friction term is either $f(y = pm|y|$ or $f(y = -y$. Note that when $f(y = -y$ and $epsilon = 1$, we have well known original damped simple pendulum equation. To understand the dependance of solutions, to the damped simple pendulum equation with $lambda gg 1$, upon the term $f(u'(t$, we present asymptotic formulas for the maximum norm of the solutions. Also we present an asymptotic formula for the time at which maximum occurs, for the case $f(u = -u$.
Electronic system for the complex measurement of a Wilberforce pendulum
Kos, B.; Grodzicki, M.; Wasielewski, R.
2018-05-01
The authors present a novel application of a micro-electro-mechanical measurement system to the description of basic physical phenomena in a model Wilberforce pendulum. The composition of the kit includes a tripod with a mounted spring with freely hanging bob, a module GY-521 on the MPU 6050 coupled with an Arduino Uno, which in conjunction with a PC acts as measuring set. The system allows one to observe the swing of the pendulum in real time. Obtained data stays in good agreement with both theoretical predictions and previous works. The aim of this article is to introduce the study of a Wilberforce pendulum to the canon of physical laboratory exercises due to its interesting properties and multifaceted method of measurement.
Pendulum Therapy of Molar Distalization in Mixed Dentition.
Patil, Raju Umaji; Prakash, Amit; Agarwal, Anshu
2016-01-01
Early and timely pedo-orthodontic treatment is aimed at eliminating the disturbances of skeletal or dentoalveolar development, to harmonize the stomatognathic system before the full eruption of all permanent teeth. The advantages of pendulum appliance are its minimal dependence on patient's compliance (child cooperation), ease of fabrication, onetime activation and adjustment of the springs if necessary to correct minor transverse and vertical molar positions. This article reports a successful treatment method of class II malocclusion with pendulum appliance in mixed dentition phase. Distalization of maxillary molar was done, followed by guidance of canine impaction orthodontically and other dental correction using 0.022 MBT appliances. Posttreatment results were stable and remarkable. How to cite this article: Patil RU, Prakash A, Agarwal A. Pendulum Therapy of Molar Distalization in Mixed Dentition. Int J Clin Pediatr Dent 2016;9(1):67-73.
A Simple Method to Measure the Trajectory of a Spherical Pendulum
Yang, Hujiang; Xiao, Jinghua; Yang, Tianyu; Qiu, Chen
2011-01-01
Compared with a single gravity pendulum, the spherical pendulum behaves more complicatedly in experiments, which makes it difficult to measure. In this paper, we present a method to visualize the trajectories of a spherical pendulum by employing a gravity ball with a lit LED and a digital camera. This new measurement is inexpensive and easy to…
Proportional Derivative Control with Inverse Dead-Zone for Pendulum Systems
Rubio, José de Jesús; Zamudio, Zizilia; Pacheco, Jaime; Mújica Vargas, Dante
2013-01-01
A proportional derivative controller with inverse dead-zone is proposed for the control of pendulum systems. The proposed method has the characteristic that the inverse dead-zone is cancelled with the pendulum dead-zone. Asymptotic stability of the proposed technique is guaranteed by the Lyapunov analysis. Simulations of two pendulum systems show the effectiveness of the proposed technique.
Stability of an autoparametric pendulum system with impacts
Alevras, P.; Bobryk, R. V.; Yurchenko, D.
2014-12-01
This paper considers a small oscillatory motion of a pendulum suspended on a single-degree-of-freedom system subjected to a narrow band excitation and impacts due to a barrier located at a certain distance from the system's equilibrium position. The influence of a impacting motion of the single-degree-of-freedom system onto the instability boundaries of the pendulum is investigated. It is demonstrated that the impacting motion significantly changes the shape of the instability domain compared to the traditional one inherent to the Mathieu equation.
On the stochastic pendulum with Ornstein-Uhlenbeck noise
International Nuclear Information System (INIS)
Mallick, Kirone; Marcq, Philippe
2004-01-01
We study a frictionless pendulum subject to multiplicative random noise. Because of destructive interference between the angular displacement of the system and the noise term, the energy fluctuations are reduced when the noise has a non-zero correlation time. We derive the long time behaviour of the pendulum in the case of Ornstein-Uhlenbeck noise by a recursive adiabatic elimination procedure. An analytical expression for the asymptotic probability distribution function of the energy is obtained and the results agree with numerical simulations. Lastly, we compare our method with other approximation schemes
The compound pendulum in intermediate laboratories and demonstrations
DEFF Research Database (Denmark)
Pedersen, Niels Falsig; Sørensen, O. Hoffmann
1977-01-01
A student laboratory course on the motion of the compound pendulum is described. The course is suited for physics and engineering students in their first year and requires a background in mechanics and mathematics corresponding to a one-semester course in these disciplines. The purpose of this co......A student laboratory course on the motion of the compound pendulum is described. The course is suited for physics and engineering students in their first year and requires a background in mechanics and mathematics corresponding to a one-semester course in these disciplines. The purpose...
Torsion of the vermiform appendix: A case report | Wani | Internet ...
African Journals Online (AJOL)
Torsion of the vermiform appendix is a rare condition with few cases reported in the literature. Various factors predispose to torsion. Various factors predispose to torsion. We report a case of primary torsion of the vermiform appendix. The clinical presentation was indistinguishable from acute appendicitis and the diagnosis ...
Acute and intermittent testicular torsion: Analysis of presentation ...
African Journals Online (AJOL)
Background: Testicular torsion compromises the blood supply to the testes and may result in testicular loss or damage if not dealt with promptly. It can occur either as acute testicular torsion (ATT) or intermittent testicular torsion (ITT). This study examines the presentation, management, and outcome of adult testicular torsion.
Measurement of tibial torsion by computer tomography
International Nuclear Information System (INIS)
Jend, H.-H.; Heller, M.; Dallek, M.; Schoettle, H.
1981-01-01
A CT procedure for objective measurements of tibial torsion independent of axial rotation in the nearby joints is described. Transverse sections in defined planes of the tibia permit easy calculation of normal and abnormal congenital or posttraumatic angles of torsion. In 69 limbs normal tibial torsion was 40 0 +-9 0 . In a series of 42 limbs with complicated healing of a fracture of both bones of the leg it is shown that tibial maltorsion is a deformity which in most cases leads to arthrosis of the ankle joint. (Auth.)
Measurement of tibial torsion by computer tomography
Energy Technology Data Exchange (ETDEWEB)
Jend, H.H.; Heller, M.; Dallek, M.; Schoettle, H. (Hamburg Univ. (Germany, F.R.))
1981-01-01
A CT procedure for objective measurements of tibial torsion independent of axial rotation in the nearby joints is described. Transverse sections in defined planes of the tibia permit easy calculation of normal and abnormal congenital or posttraumatic angles of torsion. In 69 limbs normal tibial torsion was 40/sup 0/+-9/sup 0/. In a series of 42 limbs with complicated healing of a fracture of both bones of the leg it is shown that tibial maltorsion is a deformity which in most cases leads to arthrosis of the ankle joint.
Directory of Open Access Journals (Sweden)
Wojciech HOMIK
2011-01-01
Full Text Available The short explanation of usefulness of rubber torsional dampers in crankshaft in multi-cylinder engines is presented. The description of the construction and operation of rubber torsional damper is also included. In the rubber torsional damper, the damping is achieved as the effect of internal friction resulting from the deformation of the rubber material. This deformation appears while the internal rubber elasticity is overloaded. Both the physical and mechanical rubber properties depend on temperature change. In cooperation with rubber dampers manufacturer the experimental investigations are made in order to establish the influence of temperature change on torsional stiffness and damping.
Occurrence of stable periodic modes in a pendulum with cubic ...
Indian Academy of Sciences (India)
In this work the driven Froude pendulum is studied by the harmonic balancing method; the resulting nonlinear response curves are studied further for resonance and stability of symmetric oscillations with relatively low damping. The stability analysis is carried out by transforming the system of equations to the linear Mathieu ...
Optical Foucault Pendulum: photons and the Coriolis effect
Rogers, Charles; Selvaggi, Richard
2012-10-01
Consider the motion of photons within a rotating photon clock. Will light behave as a particle as it reflects back and forth between two parallel mirrors rotating in a manner similar to the motion of a Foucault pendulum? An experiment to measure the trajectory of light in a rotating cavity is presented. Implementation details for this experiment and initial data collected are also reported.
Infinite-Scroll Attractor Generated by the Complex Pendulum Model
Directory of Open Access Journals (Sweden)
Sachin Bhalekar
2013-01-01
Full Text Available We report the finding of the simple nonlinear autonomous system exhibiting infinite-scroll attractor. The system is generated from the pendulum equation with complex-valued function. The proposed system is having infinitely many saddle points of index two which are responsible for the infinite-scroll attractor.
Human Mobile Inverted Pendulum Transporter - a Mechatronic System Case Study
DEFF Research Database (Denmark)
Bech, Michael Møller; Hansen, Anders Hedegaard; Pedersen, Henrik C.
2011-01-01
, which nevertheless illustrates the potentials of unifying classical engineering technologies (mechanics, electronics, control systems) with modern high-efficient inverter-fed permanent magnet AC motors and the latest MEMS sensor technology. A full-scale fully operational prototype of a two-wheel mobile...... inverted pendulum has been built based on the presented design....
Effective equations for the quantum pendulum from momentous quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Hernandez, Hector H.; Chacon-Acosta, Guillermo [Universidad Autonoma de Chihuahua, Facultad de Ingenieria, Nuevo Campus Universitario, Chihuahua 31125 (Mexico); Departamento de Matematicas Aplicadas y Sistemas, Universidad Autonoma Metropolitana-Cuajimalpa, Artificios 40, Mexico D. F. 01120 (Mexico)
2012-08-24
In this work we study the quantum pendulum within the framework of momentous quantum mechanics. This description replaces the Schroedinger equation for the quantum evolution of the system with an infinite set of classical equations for expectation values of configuration variables, and quantum dispersions. We solve numerically the effective equations up to the second order, and describe its evolution.
Oscillatory variation of anomalous diffusion in pendulum systems
Indian Academy of Sciences (India)
driven and parametrically-driven pendulum systems are presented. When the frequency of the periodic driving force is varied, the exponent μ, which is the rate of divergence of the mean square displacement with time, is found to vary in an ...
The Slinky Wilberforce pendulum: A simple coupled oscillator
Mewes, Matthew
2014-03-01
The Wilberforce pendulum is an effective classroom demonstration of coupled oscillations and the beat-like behavior that arises in weakly coupled tuned oscillators. We describe a simple and inexpensive version constructed from a Slinky spring toy and a soup can.
Pendulum Underwater--An Approach for Quantifying Viscosity
Leme, José Costa; Oliveira, Agostinho
2017-01-01
The purpose of the experiment presented in this paper is to quantify the viscosity of a liquid. Viscous effects are important in the flow of fluids in pipes, in the bloodstream, in the lubrication of engine parts, and in many other situations. In the present paper, the authors explore the oscillations of a physical pendulum in the form of a long…
The Pendulum: From Constrained Fall to the Concept of Potential
Bevilacqua, Fabio; Falomo, Lidia; Fregonese, Lucio; Giannetto, Enrico; Giudice, Franco; Mascheretti, Paolo
2006-01-01
Kuhn underlined the relevance of Galileo's gestalt switch in the interpretation of a swinging body from constrained fall to time metre. But the new interpretation did not eliminate the older one. The constrained fall, both in the motion of pendulums and along inclined planes, led Galileo to the law of free fall. Experimenting with physical…
An Experiment on a Physical Pendulum and Steiner's Theorem
Russeva, G. B.; Tsutsumanova, G. G.; Russev, S. C.
2010-01-01
Introductory physics laboratory curricula usually include experiments on the moment of inertia, the centre of gravity, the harmonic motion of a physical pendulum, and Steiner's theorem. We present a simple experiment using very low cost equipment for investigating these subjects in the general case of an asymmetrical test body. (Contains 3 figures…
Dynamic Behavior of a Friction Pendulum with Elastomeric Layer
Directory of Open Access Journals (Sweden)
Gilbert-Rainer Gillich
2012-01-01
Full Text Available Transient dynamic characteristics of a friction pendulum can be determined using experimental ways. Nowadays, numerical simulation techniques allow obtaining these characteristics using mathematical models. The express advantage is represented by almost unlimited possibilities to extract and quantified in the regime of "post processing" regarding the results. In terms of efficiency this means increased performance regarding the research and product development.
A numerical analysis of chaos in the double pendulum
Energy Technology Data Exchange (ETDEWEB)
Stachowiak, Tomasz [Astronomical Observatory, Jagiellonian University, Orla 171, 30-244 Cracow (Poland)]. E-mail: toms@oa.uj.edu.pl; Okada, Toshio [Tokyo University of Agriculture and Technology, Naka-machi, Koganei-shi, Tokyo 184-8588 (Japan)]. E-mail: okada@cc.tuat.ac.jp
2006-07-15
We analyse the double pendulum system numerically, using a modified mid-point integrator. Poincare sections and bifurcation diagrams are constructed for certain, characteristic values of energy. The largest Lyapunov characteristic exponents are also calculated. All three methods confirm the passing of the system from the regular low-energy limit into chaos as energy is increased.
Galileo and the Pendulum: Latching on to Time
Machamer, Peter; Hepburn, Brian
Galileo changed the very concepts or categories by which natural philosophy could deal with matter and motion. Central to these changes was his introduction of time as a fundamental concept. He worked with the pendulum and with the inclined plane to discover his new concept of motion. Both of these showed him that acceleration and time were important for making motion intelligible.
Chaotic behaviour of a pendulum with variable length
International Nuclear Information System (INIS)
Bartuccelli, M.; Christiansen, P.L.; Muto, V.; Soerensen, M.P.; Pedersen, N.F.
1987-01-01
The Melnikov function for the prediction of Smale horseshoe chaos is applied to a driven damped pendulum with variable length. Depending on the parameters, it is shown that this dynamical system undertakes heteroclinic bifurcations which are the source of the unstable chaotic motion. The analytical results are illustrated by new numerical simulations. Furthermore, using the averaging theorem, the stability of the subharmonics is studied
On the JWKB solution of the uniformly lengthening pendulum via ...
Indian Academy of Sciences (India)
Common recipe for the lengthening pendulum (LP) involves some change of variables to give a relationship with the Bessel's equation. In this work, conventional semiclassical JWKB solution (named after Jeffreys, Wentzel, Kramers and Brillouin) of the LP is being obtained by first transforming the related Bessel's equation ...
Pendulum impact tests of wooden and steel highway guardrail posts
Charles J. Gatchell; Jarvis D. Michie
1974-01-01
Impact strength characteristics of southern pine, red oak, and steel highway guardrail posts were evaluated in destructive impact testing with a 4,000-pound pendulum at the Southwest Research Institute. Effects were recorded with high-speed motion-picture equipment. Comparisons were based on reactions to the point of major post failure. Major comparisons of 6x6-inch...
Isolated torsion of fallopian tube. Radiological findings
International Nuclear Information System (INIS)
Tomas Fanjul, L.; Aldea Martinez, J.; Fernandez Matia, G.; Rodrigo Verguizas, J.; Fernandez Alvarez, G.; Galindo Vicente, M.C.
1993-01-01
Isolated tubal torsion is a very uncommon disorder that is rarely diagnosed preoperatively. We present a case and review the literature, which only provides ultrasonographic findings in 5 cases reported to date. 11 refs
Torsion sensing based on patterned piezoelectric beams
Cha, Youngsu; You, Hangil
2018-03-01
In this study, we investigated the sensing characteristics of piezoelectric beams under torsional loads. We used partially patterned piezoelectric beams to sense torsion. In particular, the piezoelectric patches are located symmetrically with respect to the line of the shear center of the beam. The patterned piezoelectric beam is modeled as a slender beam, and its electrical responses are obtained by piezoelectric electromechanical equations. To validate the modeling framework, experiments are performed using a setup that forces pure torsional deformation. Three different geometric configurations of the patterned piezoelectric layer are used for the experiments. The frequency and amplitude of the forced torsional load are systematically varied in order to study the behavior of the piezoelectric sensor. Experimental results demonstrate that two voltage outputs of the piezoelectric beam are approximately out of phase with identical amplitude. Moreover, the length of the piezoelectric layers has a significant influence on the sensing properties. Our theoretical predictions using the model support the experimental findings.
Internal torsion resistance in deflected shafts
Directory of Open Access Journals (Sweden)
Mahmoud T. El-Sayed
2017-06-01
The objective of the present work was to estimate the effect of internal torsional resistance in shafts which is caused by deflection, for the reason that it has the upper hand on misalignment problem. With the aim of fulfilling this objective, an experimental rig has been constructed to verify the existence of the torsional resistance in deflected shafts and its variation with the rotation angle.
Torsion and geometrostasis in covariant superstrings
Energy Technology Data Exchange (ETDEWEB)
Zachos, C.
1985-01-01
The covariant action for freely propagating heterotic superstrings consists of a metric and a torsion term with a special relative strength. It is shown that the strength for which torsion flattens the underlying 10-dimensional superspace geometry is precisely that which yields free oscillators on the light cone. This is in complete analogy with the geometrostasis of two-dimensional sigma-models with Wess-Zumino interactions. 13 refs.
Torsion of Wandering Gallbladder following Colonoscopy
Directory of Open Access Journals (Sweden)
Sean R. Warfe
2013-01-01
Full Text Available Torsion of the gallbladder is an uncommon condition that may present as an acute abdomen. Its preoperative diagnosis can often be challenging due to its variable presentation, with specific sonographic signs seen infrequently. We describe, to our knowledge, the first case of torsion of a wandering gallbladder following a colonoscopy in a 69-year-old female who presented with acute abdominal pain after procedure. This was discovered intraoperatively, and after a subsequent cholecystectomy, she had an uncomplicated recovery.
Strain-independent fiber torsion and displacement sensor based on acoustically-induced fiber grating
Liu, Yu; Ren, Guobin; Jiang, Youchao; Mi, Yuean; Li, Haisu; Zhu, Bofeng; Yang, Yuguang; Shen, Ya; Jian, Shuisheng
2018-02-01
We present a strain-independent torsion and displacement fiber sensor using acoustically-induced fiber grating (AIFG) in dual-mode fiber (DMF). By tuning the radio frequency of driving signal, LP01 and LP11 modes generated by the AIFG can be exploited to measure the dynamic displacement and torsion variations, respectively. Both the twist angle and the twist direction can be monitored via image detection facility at the end of DMF. Between torsion angles of -80° and 80°, the highest twist sensitivity reaches 15 pixel/°. The average displacement sensitivity is 5 pixel/μm within the recorded two-dimensional movement of 100um × 80um. The stable property of sensor is verified when the strain is varied from 100 με to 1500 με.
Attentional Modulation of Eye Torsion Responses
Stevenson, Scott B.; Mahadevan, Madhumitha S.; Mulligan, Jeffrey B.
2016-01-01
Eye movements generally have both reflexive and voluntary aspects, but torsional eye movements are usually thought of as a reflexive response to image rotation around the line of sight (torsional OKN) or to head roll (torsional VOR). In this study we asked whether torsional responses could be modulated by attention in a case where two stimuli rotated independently, and whether attention would influence the latency of responses. The display consisted of rear-projected radial "pinwheel" gratings, with an inner annulus segment extending from the center to 22 degrees eccentricity, and an outer annulus segment extending from 22 degrees out to 45 degrees eccentricity. The two segments rotated around the center in independent random walks, stepping randomly 4 degrees clockwise or counterclockwise at 60 Hz. Subjects were asked to attend to one or the other while keeping fixation steady at the center of the display. To encourage attention on one or the other segment of the display, subjects were asked to move a joystick in synchrony with the back and forth rotations of one part of the image while ignoring the other. Eye torsion was recorded with the scleral search coil technique, sampled at 500 Hz. All four subjects showed roughly 50% stronger torsion responses to the attended compared to unattended segments. Latency varied from 100 to 150 msec across subjects and was unchanged by attention. These findings suggest that attention can influence eye movement responses that are not typically under voluntary control.
Twist buckling of veins under torsional loading.
Garcia, Justin R; Sanyal, Arnav; Fatemifar, Fatemeh; Mottahedi, Mohammad; Han, Hai-Chao
2017-06-14
Veins are often subjected to torsion and twisted veins can hinder and disrupt normal blood flow but their mechanical behavior under torsion is poorly understood. The objective of this study was to investigate the twist deformation and buckling behavior of veins under torsion. Twist buckling tests were performed on porcine internal jugular veins (IJVs) and human great saphenous veins (GSVs) at various axial stretch ratio and lumen pressure conditions to determine their critical buckling torques and critical buckling twist angles. The mechanical behavior under torsion was characterized using a two-fiber strain energy density function and the buckling behavior was then simulated using finite element analysis. Our results demonstrated that twist buckling occurred in all veins under excessive torque characterized by a sudden kink formation. The critical buckling torque increased significantly with increasing lumen pressure for both porcine IJV and human GSV. But lumen pressure and axial stretch had little effect on the critical twist angle. The human GSVs are stiffer than the porcine IJVs. Finite element simulations captured the buckling behavior for individual veins under simultaneous extension, inflation, and torsion with strong correlation between predicted critical buckling torques and experimental data (R 2 =0.96). We conclude that veins can buckle under torsion loading and the lumen pressure significantly affects the critical buckling torque. These results improve our understanding of vein twist behavior and help identify key factors associated in the formation of twisted veins. Copyright © 2017 Elsevier Ltd. All rights reserved.
Torsional oscillations of strange stars
Directory of Open Access Journals (Sweden)
Mannarelli Massimo
2014-01-01
Full Text Available Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 1045 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.
Directory of Open Access Journals (Sweden)
V. A. Gribkov
2015-01-01
Full Text Available We consider the multilink pendulum system consisting of six physical pendulums. A pendulum (carrier has inertia parameters, which significantly exceed the remaining (carried ones placed on the carrier. In addition to the system under analysis, in particular, the paper presents a design scheme for a two-stage liquid fuel rocket using pendulums as the analogues of fluctuating fuel. Pendulum models also find application to solve problems of stabilization of space tether systems. The objective of the study is to determine dynamic characteristics of the said sixmembered pendulum system, as well as to identify specific dynamic properties inherent in objects of this kind. Dynamic characteristics of the system are determined by calculations. A physical model of the pendulum allowed us to compare the calculated and experimental results. To conduct the frequency tests of the pendulum model three pilot units have been created. The first two units turned out to be inappropriate for fulfilling the experimental tasks for various reasons. The third unit enabled us to obtain desirable experimental results. The "calculation–experiment” discrepancy on the natural frequencies of the pendulum model for the majority of frequencies was less than 5%. We analyzed the dynamic features of multilink pendulum systems "carried by the carrier unit links". The analysis results are applicable to the above-noted object classes of rocket and space technology.
Torsion profiling of proteins using magnetic particles.
van Reenen, A; Gutiérrez-Mejía, F; van Ĳzendoorn, L J; Prins, M W J
2013-03-05
We report a method to profile the torsional spring properties of proteins as a function of the angle of rotation. The torque is applied by superparamagnetic particles and has been calibrated while taking account of the magnetization dynamics of the particles. We record and compare the torsional profiles of single Protein G-Immunoglobulin G (IgG) and IgG-IgG complexes, sandwiched between a substrate and a superparamagnetic particle, for torques in the range between 0.5 × 10(3) and 5 × 10(3) pN·nm. Both molecular systems show torsional stiffening for increasing rotation angle, but the elastic and inelastic torsion stiffnesses are remarkably different. We interpret the results in terms of the structural properties of the molecules. The torsion profiling technique opens new dimensions for research on biomolecular characterization and for research on bio-nanomechanical structure-function relationships. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Foucault's pendulum, a classical analog for the electron spin state
Linck, Rebecca A.
Spin has long been regarded as a fundamentally quantum phenomena that is incapable of being described classically. To bridge the gap and show that aspects of spin's quantum nature can be described classically, this work uses a classical Lagrangian based on the coupled oscillations of Foucault's pendulum as an analog for the electron spin state in an external magnetic field. With this analog it is possible to demonstrate that Foucault's pendulum not only serves as a basis for explaining geometric phase, but is also a basis for reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured electron spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.
Experimental study on a pendulum wave energy converter
Qiu, Shou-qiang; Ye, Jia-wei; Wang, Dong-jiao; Liang, Fu-lin
2013-06-01
Many of the existing wave energy converters (WEC) are of oscillating water column (OWC) and point absorber (PA) types. Fewer references have been published in public on the pendulum type WEC. A series of experimental tests on a bottom-hinged pendulum WEC model are carried out and some results are revealed in the present study. The purpose of this paper is to present a detailed description of the tests. It is found that wave energy conversion efficiency varies with the applied damping and wave conditions. In addition, special attention is given to the effect of the water ballast on the efficiency of the wave energy converter. It is demonstrated that the ballast plays an important role in energy extraction. Better understanding on how the performance of the device is influenced by damping, wave height, wave period and ballast is shown.
Suspension for the low frequency facility
Cella, G; Di Virgilio, A; Gaddi, A; Viceré, A
2000-01-01
We introduce the working principles of the VIRGO Low Frequency Facility (LFF), whose main aim is the measurement of the thermal noise in the VIRGO suspension system. We evaluate the displacement thermal noise of a mirror, which is an intermediate element of a double pendulum suspension system. This double pendulum will be suspended to the last stage of a VIRGO Super-Attenuator (SA), the prototype VIRGO suspension system being tested at the Pisa section of INFN. In the proposed configuration, we evaluate the spectrum of the thermal noise for different choices of the parameters: based on this study, we comment on the future directions to be undertaken in the LFF experiment.
Effects of springs on a pendulum electromechanical energy harvester
Directory of Open Access Journals (Sweden)
Arnaud Notué Kadjie
2014-01-01
Full Text Available This paper studies a model of energy harvester that consists of an electromechanical pendulum system subjected to nonlinear springs. The output power is analyzed in terms of the intrinsic parameters of the device leading to optimal parameters for energy harvesting. It is found that in an appropriate range of the springs constant, the power attains higher values as compared to the case without springs. The dynamical behavior of the device shows transition to chaos.
Effects of springs on a pendulum electromechanical energy harvester
Arnaud Notué Kadjie; Paul Woafo
2014-01-01
This paper studies a model of energy harvester that consists of an electromechanical pendulum system subjected to nonlinear springs. The output power is analyzed in terms of the intrinsic parameters of the device leading to optimal parameters for energy harvesting. It is found that in an appropriate range of the springs constant, the power attains higher values as compared to the case without springs. The dynamical behavior of the device shows transition to chaos.
Learning by experience on the example of mathematic pendulum
Horváth, Peter
2017-01-01
The very suitable topic for independent student activities is the investigation of factors influencing an oscillation period of the mathematic pendulum. The article describes the experience from particular lessons. Students themselves were discovering new facts. They learned about the physics practice of acquiring new knowledge. The knowledge quality and retention was compared between the experimental classes and classes with a traditional instruction one year after the experiment.
Inverted Pendulum-type Personal Mobility Considering Human Vibration Sensitivity
Misaki Masuda; Takuma Suzuki; Kazuto Yokoyama
2014-01-01
An inverted pendulum-type PM (personal mobility) has been attracting attention as a low-carbon vehicle. For many people who like to use the PM, ride comfort is important. However, ride comfort of PM has not been focused on in previous studies. The vibration is one of causes that make riders feel uncomfortable. The PM is unstable system and horizontal vibration may be caused by a stabilizing control. Additionally, vertical vibration may also be caused by road disturbances. This study analyzes ...
Analysis and design of controllers for a double inverted pendulum
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Poulsen, J K
2003-01-01
A physical control problem is studied with the μ methodology. The issues of modelling, uncertainty modelling, performance specification, controller design and laboratory implementation are discussed. The laboratory experiment is a double inverted pendulum placed on a cart. The limitations...... in the system with respect to performance are the limitation in the control signal and the limitation of the movement of the chart. It is shown how these performance limitation will effect the design of a μ controller for the system....
Hybrid LQG-Neural Controller for Inverted Pendulum System
Sazonov, E. S.; Klinkhachorn, P.; Klein, R. L.
2003-01-01
The paper presents a hybrid system controller, incorporating a neural and an LQG controller. The neural controller has been optimized by genetic algorithms directly on the inverted pendulum system. The failure free optimization process stipulated a relatively small region of the asymptotic stability of the neural controller, which is concentrated around the regulation point. The presented hybrid controller combines benefits of a genetically optimized neural controller and an LQG controller in...
Approximation for a large-angle simple pendulum period
International Nuclear Information System (INIS)
Belendez, A; Rodes, J J; Belendez, T; Hernandez, A
2009-01-01
An approximation scheme to obtain the period for large amplitude oscillations of a simple pendulum is analysed and discussed. The analytical approximate formula for the period is the same as that suggested by Hite (2005 Phys. Teach. 43 290), but it is now obtained analytically by means of a term-by-term comparison of the power-series expansion for the approximate period with the corresponding series for the exact period. (letters and comments)
Rotary inverted pendulum: Trajectory tracking via nonlinear control techniques
Czech Academy of Sciences Publication Activity Database
Ramos-Velasco, Luis Enrique; Ruiz-León, J. J.; Čelikovský, Sergej
2002-01-01
Roč. 38, č. 2 (2002), s. 217-232 ISSN 0023-5954 R&D Projects: GA ČR GA102/02/0709 Grant - others: CONACYT (MX) 31844-A Institutional research plan: CEZ:AV0Z1075907 Keywords : nonlinear systems * rotary inverted pendulum * output regulation * sliding modes Subject RIV: BC - Control Systems Theory Impact factor: 0.341, year: 2002
Damping Effects Induced by a Mass Moving along a Pendulum
Directory of Open Access Journals (Sweden)
E. Gandino
2014-01-01
Full Text Available The experimental study of damping in a time-varying inertia pendulum is presented. The system consists of a disk travelling along an oscillating pendulum: large swinging angles are reached, so that its equation of motion is not only time-varying but also nonlinear. Signals are acquired from a rotary sensor, but some remarks are also proposed as regards signals measured by piezoelectric or capacitive accelerometers. Time-varying inertia due to the relative motion of the mass is associated with the Coriolis-type effects appearing in the system, which can reduce and also amplify the oscillations. The analytical model of the pendulum is introduced and an equivalent damping ratio is estimated by applying energy considerations. An accurate model is obtained by updating the viscous damping coefficient in accordance with the experimental data. The system is analysed through the application of a subspace-based technique devoted to the identification of linear time-varying systems: the so-called short-time stochastic subspace identification (ST-SSI. This is a very simple method recently adopted for estimating the instantaneous frequencies of a system. In this paper, the ST-SSI method is demonstrated to be capable of accurately estimating damping ratios, even in the challenging cases when damping may turn to negative due to the Coriolis-type effects, thus causing amplifications of the system response.
Ocular torsional movements in normal humans.
Kushner, B J; Kraft, S
1983-06-01
We conducted three studies of compensatory ocular torsional movements in normal human subjects, using changes in the axis of astigmatism, afterimages, and direct observation with cinematography. Measurements of changes in the axis of astigmatism and the subjects' subjective perception of afterimages with a superimposed Maddox rod showed a partial compensatory intorsion on head tilt to the ipsilateral side and extorsion on head tilt to the contralateral side. Cinematography demonstrated that the eye lags behind the head in a slow rolling movement as the head is tilted. Periodic rotary movements in the direction of the head tilt partially correct the lag and result in a partial compensatory torsion. A fourth experiment excluded false torsion as an artifact in these studies.
Torsional rigidity of submanifolds with controlled geometry
DEFF Research Database (Denmark)
Hurtado, Ana; Markvorsen, Steen; Palmer, Vicente
2009-01-01
We prove explicit upper and lower bounds for the torsional rigidity of extrinsic domains of submanifolds ^m$ with controlled radial mean curvature in ambient Riemannian manifolds ^n$ with a pole $ and with sectional curvatures bounded from above and from below, respectively. These bounds are given...... in terms of the torsional rigidities of corresponding Schwarz symmetrizations of the domains in warped product model spaces. Our main results are obtained using methods from previously established isoperimetric inequalities, as found in e.g. [MP4] and [MP5]. As in [MP4] we also characterize the geometry...... of those situations in which the bounds for the torsional rigidity are actually attained and study the behavior at infinity of the so-called geometric average of the mean exit time for Brownian motion....
Residual strain evolution in steel samples: tension versus torsion
Bunn, J. R.; Penumadu, D.; Hubbard, C. R.
2010-06-01
Torsion provides a unique opportunity to probe mechanical behavior of materials subjected to pure state of shear stress. In this research, identical steel alloy (12L14) hollow cylinder samples are subjected to predetermined amounts of plastic axial and shear strain such that their octahedral shear strain (an invariant) are identical for comparison. Measurements were made at the residual stress measuring facility at the High Flux Isotope Reactor in Oak Ridge (NRSF2), using a small gauge area in the direction of strain gradients (0.5 mm×0.5 mm) through the hollow cylinder wall thickness. These orthogonal strains are obtained for BCC Fe for three hkl’s. Three normal strains in the hoop, radial, and axial directions are obtained as a function of centroid position of the gauge volume through the 2 mm wall thickness. Significant differences in measured residual strains are noted between the torsion and the tension samples. The largest differences are found for the Fe (200) planes while the smallest differences are observed for the Fe (211) planes. This research demonstrates the need for a systematic study of residual strain as a function of applied stress path moving beyond tensile testing for solving real world problems.
Steffen, Heimo; Straumann, Dominik S; Walker, Mark F; Miller, Neil R; Guyton, David L; Repka, Michael X; Zee, David S
2008-05-01
The purpose was to assess intra- and post-saccadic torsion in superior oblique palsy (SOP) patients and the effect of surgery on torsion. Eleven patients with a presumed congenital SOP and five with acquired SOP performed 10 degrees vertical saccades over a range of +/-20 degrees. Eye movements were recorded with dual search coils. Dynamic torsion was calculated by subtracting the expected change in torsion during the saccade (based upon static torsion before and after the saccade) from the maximum intrasaccadic torsion. Eight healthy subjects were controls. We also examined the effects of surgery on dynamic torsion and the orientation of Listing's plane in patients with congenital SOP who were operated on either by weakening of the inferior oblique muscle on the affected eye (n=5), by recession of the inferior rectus muscle on the normal eye (n=4) or by both procedures (n=2). Postoperative recordings were obtained at least 1 month after surgery. Patients with congenital and acquired SOP showed an increased dynamic extorsion, primarily during downward saccades. Following a recession of the inferior oblique muscle in congenital SOP patients, half showed significant decreases in extorsion (up to 1.0 degrees) during downward saccades by the affected eye. Following surgery all showed a temporal rotation of Listing's plane (up to 15 degrees for primary position). Patients with a SOP show a characteristic pattern of dynamic torsion during vertical saccades differing from normals. Recession of the inferior oblique muscle leads to rotation of Listing's plane in all congenital SOP patients and causes large changes in dynamic torsion in a subgroup of them, perhaps reflecting the heterogeneity of congenital SOP.
The relationship between torsional rigidity and bending strength ...
African Journals Online (AJOL)
torsional buckling resistance of bending members and when members are subjected to torsional loads. This study was based on a series of laboratory experiments on actual sized timber with the focus and emphasis on mechanical properties and ...
Torsional Behavior of Axonal Microtubule Bundles
Lazarus, Carole; Soheilypour, Mohammad; Mofrad, Mohammad R.K.
2015-01-01
Axonal microtubule (MT) bundles crosslinked by microtubule-associated protein (MAP) tau are responsible for vital biological functions such as maintaining mechanical integrity and shape of the axon as well as facilitating axonal transport. Breaking and twisting of MTs have been previously observed in damaged undulated axons. Such breaking and twisting of MTs is suggested to cause axonal swellings that lead to axonal degeneration, which is known as “diffuse axonal injury”. In particular, overstretching and torsion of axons can potentially damage the axonal cytoskeleton. Following our previous studies on mechanical response of axonal MT bundles under uniaxial tension and compression, this work seeks to characterize the mechanical behavior of MT bundles under pure torsion as well as a combination of torsional and tensile loads using a coarse-grained computational model. In the case of pure torsion, a competition between MAP tau tensile and MT bending energies is observed. After three turns, a transition occurs in the mechanical behavior of the bundle that is characterized by its diameter shrinkage. Furthermore, crosslink spacing is shown to considerably influence the mechanical response, with larger MAP tau spacing resulting in a higher rate of turns. Therefore, MAP tau crosslinking of MT filaments protects the bundle from excessive deformation. Simultaneous application of torsion and tension on MT bundles is shown to accelerate bundle failure, compared to pure tension experiments. MAP tau proteins fail in clusters of 10–100 elements located at the discontinuities or the ends of MT filaments. This failure occurs in a stepwise fashion, implying gradual accumulation of elastic tensile energy in crosslinks followed by rupture. Failure of large groups of interconnecting MAP tau proteins leads to detachment of MT filaments from the bundle near discontinuities. This study highlights the importance of torsional loading in axonal damage after traumatic brain injury
Stabilizing Planar Inverted Pendulum System Based on Fuzzy Nine-point Controller
Qi Qian; Liu Feng; Tang Yong-chuan; Yang Yang
2013-01-01
In order to stabilize planar inverted pendulum, after analyzing the physical characteristics of the planar inverted pendulum system, a pendulum nine-point controller and a car nine-point controller for X-axis and Y-axis were designed respectively. Then a fuzzy coordinator was designed using the fuzzy control theory based on the priority of those two controllers, and the priority level of the pendulum is higher than the car. Thus, the control tasks of each controller in each axis were harmoniz...
On the geometrization of electromagnetism by torsion
International Nuclear Information System (INIS)
Fonseca Neto, J.B. da.
1984-01-01
The possibility of electromagnetism geometrization using an four dimension Cartan geometry is investigated. The Lagrangian density which presents dual invariance for dyons electrodynamics formulated in term of two potentials is constructed. This theory by association of two potentials with track and with torsion pseudo-track and of the field with torsion covariant divergent is described. The minimum coupling of particle gravitational field of scalar and spinorial fields with dyon geometry theory by the minimum coupling of these fields with Cartan geometry was obtained. (author)
The torsion of the multicell sections
Directory of Open Access Journals (Sweden)
Marcel STERE
2010-09-01
Full Text Available The paper is focused on the stress analysis of thin-walled multicell sections subjected to pure torsion. The shear flow and stiffness characteristics of the cross section for torsion are given. Example: aircraft wing section. The theory for thin-walled closed sections used in this paper was developed by Bredt [3]. The shear flows obtained are used in the design of skins and interior webs, ribs and fasteners at skin splices, skin web junctions and the joints where the ribs meet the skin or webs.
Disseminated peritoneal leiomyomatosis mimicking ovarian torsion
Directory of Open Access Journals (Sweden)
Chau-Yang Tyan
2015-01-01
Full Text Available The presentation of disseminated peritoneal leiomyomatosis (DPL can be misleading. Herein, we present the case of a 42-year-old nulliparous female who had previously undergone a total hysterectomy and presented with an acute abdomen. A presumptive diagnosis of ovarian torsion was made based on the clinical findings and an ultrasonographic examination. A diagnostic laparoscopy was performed immediately. DPL was subsequently diagnosed based on an intra-operative frozen section during surgical exploration and the final histopathologic examination. This case illustrates an atypical presentation of DPL mimicking ovarian torsion.
Torsional Performance of Wind Turbine Blades
DEFF Research Database (Denmark)
Branner, Kim; Berring, Peter; Berggreen, Christian
2007-01-01
The present work investigates how well different finite element modeling techniques can predict bending and torsion behavior of a wind turbine blade. Two shell models are investigated. One model has element offsets and the other has the elements at the mid-thickness surfaces of the model. The last...... two models investigated use a combination of shell and solid elements. The results from the numerical investigations are compared with measurements from testing of a section of a full-scale wind turbine blade. It is found that only the combined shell/solid models give reliable results in torsion. Both...
Torsion of the fallopian tube: progression of sonographic features.
Richard, H M; Parsons, R B; Broadman, K F; Shapiro, R S; Yeh, H C
1998-09-01
Isolated torsion of the fallopian tube is a rare gynecologic condition that is difficult to diagnose preoperatively. We present the sonographic and CT findings over a 48-hour period in a case of isolated torsion of the fallopian tube. The radiologic features of isolated torsion have been described previously; however, to our knowledge, the progressive findings have not been previously reported.
Testicular torsion: case report | Kuremu | East African Medical Journal
African Journals Online (AJOL)
This is a report of bilateral testicular torsion. The objective of the report is to highlight the serious implications of misdiagnosis of testicular torsion. Other than loss of the testis due to necrosis in unilateral torsion, immunological damage of the opposite testis occurs. Early, accurate diagnosis, and institution of the appropriate ...
Plant-based torsional actuator with memory
Nayomi Plaza; Samuel L. Zelinka; Don S. Stone; Joseph E. Jakes
2013-01-01
A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-...
FLEXURAL, TORSIONAL AND DISTORTIONAL BUCKLING OF ...
African Journals Online (AJOL)
neutral equilibrium of axially compressed single-cell box column with deformable cross-sections. The study ... FLEXURAL, TORSIONAL AND DISTORTIONAL BUCKLING OF SINGLE-CELL THIN-WALLED BOX COLUMNS cr. P : Critical buckling load. S: ... and v of a thin-walled closed structure in series form as follows: (1).
Torsional Performance of Wind Turbine Blades
DEFF Research Database (Denmark)
Branner, Kim; Berring, Peter; Berggreen, Christian
2007-01-01
The present work investigates how well different finite element modeling techniques can predict bending and torsion behavior of a wind turbine blade. Two shell models are investigated. One model has element offsets and the other has the elements at the mid-thickness surfaces of the model. The las...
Torsion of the gallbladder: a case report
Directory of Open Access Journals (Sweden)
Ijaz Samia
2008-07-01
Full Text Available Abstract Introduction Torsion of the gallbladder is a rare condition that most commonly affects the elderly. Pre-operative diagnosis is the exception rather than the rule. Any delay in treatment can be fatal as the gallbladder may rupture, leading to biliary peritonitis. Case presentation We present the case of an 80-year-old woman who was admitted with right upper quadrant pain initially thought to be secondary to acute cholecystitis. Subsequent ultrasound and computed tomography scans of the abdomen revealed signs suggestive of acute cholecystitis but neither modality detected any gallstones. As the patient's symptoms failed to resolve on conservative management, she was taken to theatre for an open cholecystectomy. Intra-operatively, the gallbladder had undergone complete torsion and appeared gangrenous. A routine cholecystectomy followed and she recovered from the operation without incident. Conclusion It is rare to diagnose torsion of the gallbladder pre-operatively despite advances in diagnostic imaging. However, this differential diagnosis should be borne in mind particularly in the elderly patient, without proven gallstones, who fails to improve on conservative management. An emergency cholecystectomy is indicated in the event of diagnosing torsion of the gallbladder to avert the potentially lethal sequelae of biliary peritonitis.
Management and Outcome of Testicular Torsion
African Journals Online (AJOL)
multiruka1
MSH, AFS, CGH: Research International East. Africa Limited. Coast Province General Hospital report 2015. 8. Lee SM, Huh JS, BaekM, et al. A Nationwide. Epidemiological Study of Testicular Torsion in. Korea. J Korean Med Sci. 2014; 29(12): 1684–1687. 9. Cattolica EV, Karol JB, Rankin KN, et al. High. Testicular Salvage ...
Right paratesticular abscess mimicking neonatal testicular torsion ...
African Journals Online (AJOL)
U.O. Ezomike
Right paratesticular abscess mimicking neonatal testicular torsion and caused by Proteus mirabilis. U.O. Ezomikea,∗. , M.A. Ituena, S.C. Ekpemoa, S.O. Ekenzeb a Department of Surgery, Federal Medical Centre Umuahia, Abia State, Nigeria b Sub-Department of Pediatric Surgery, University of Nigeria Teaching Hospital, ...
Conformal deformation of Riemann space and torsion
International Nuclear Information System (INIS)
Pyzh, V.M.
1981-01-01
Method for investigating conformal deformations of Riemann spaces using torsion tensor, which permits to reduce the second ' order equations for Killing vectors to the system of the first order equations, is presented. The method is illustrated using conformal deformations of dimer sphere as an example. A possibility of its use when studying more complex deformations is discussed [ru
Torsion of the gallbladder: a case report.
Ijaz, Samia; Sritharan, Kaji; Russell, Neil; Dar, Manzoor; Bhatti, Tahir; Ormiston, Michael
2008-07-24
Torsion of the gallbladder is a rare condition that most commonly affects the elderly. Pre-operative diagnosis is the exception rather than the rule. Any delay in treatment can be fatal as the gallbladder may rupture, leading to biliary peritonitis. We present the case of an 80-year-old woman who was admitted with right upper quadrant pain initially thought to be secondary to acute cholecystitis. Subsequent ultrasound and computed tomography scans of the abdomen revealed signs suggestive of acute cholecystitis but neither modality detected any gallstones. As the patient's symptoms failed to resolve on conservative management, she was taken to theatre for an open cholecystectomy. Intra-operatively, the gallbladder had undergone complete torsion and appeared gangrenous. A routine cholecystectomy followed and she recovered from the operation without incident. It is rare to diagnose torsion of the gallbladder pre-operatively despite advances in diagnostic imaging. However, this differential diagnosis should be borne in mind particularly in the elderly patient, without proven gallstones, who fails to improve on conservative management. An emergency cholecystectomy is indicated in the event of diagnosing torsion of the gallbladder to avert the potentially lethal sequelae of biliary peritonitis.
Pseudotopological quasilocal energy of torsion gravity
Ko, Sheng-Lan; Lin, Feng-Li; Ning, Bo
2017-08-01
Torsion gravity is a natural extension to Einstein gravity in the presence of fermion matter sources. In this paper we adopt Wald's covariant method of calculating the Noether charge to construct the quasilocal energy of the Einstein-Cartan-fermion system, and find that its explicit expression is formally independent of the coupling constant between the torsion and axial current. This seemingly topological nature is unexpected and is reminiscent of the quantum Hall effect and topological insulators. However, a coupling dependence does arise when evaluating it on shell, and thus the situation is pseudotopological. Based on the expression for the quasilocal energy, we evaluate it for a particular solution on the entanglement wedge and find agreement with the holographic relative entropy obtained before. This shows the equivalence of these two quantities in the Einstein-Cartan-fermion system. Moreover, the quasilocal energy in this case is not always positive definite, and thus it provides an example of a swampland in torsion gravity. Based on the covariant Noether charge, we also derive the nonzero fermion effect on the Komar angular momentum. The implications of our results for future tests of torsion gravity in gravitational-wave astronomy are also discussed.
The spectrum of axisymmetric torsional Alfven waves
International Nuclear Information System (INIS)
Sy, W.N.
1977-03-01
The spectrum of axisymmetric torsional Alfven waves propagating in a cylindrical, non-uniform, resistive plasma waveguide has been analysed by a method of singular perturbations. A simple condition has been derived which predicts whether the spectrum is continuous or discrete under given physical conditions. Application of this result to resolve an apparent discrepancy in experimental observations is briefly discussed. (Author)
Including Torsional Anharmonicity in Canonical and Microcanonical Reaction Path Calculations.
Zheng, Jingjing; Truhlar, Donald G
2013-07-09
We reformulate multistructural variational transition state theory by removing the approximation of calculating torsional anharmonicity only at stationary points. The multistructural method with torsional anharmonicity is applied to calculate the reaction-path free energy of the hydrogen abstraction from the carbon-1 position in isobutanol by OH radical. The torsional potential anharmonicity along the reaction path is taken into account by a coupled torsional potential. The calculations show that it can be critical to include torsional anharmonicity in searching for canonical and microcanonical variational transition states. The harmonic-oscillator approximation fails to yield reasonable free energy curves along the reaction path.
[Conservative surgery of ovarian torsion in pediatrics].
Abad, P; Rigol, S; Ezzedine, H; Durán, C; Ortega, D; Martí, M; Pinyot, J
2003-10-01
The authors describe the case of two girls diagnosed of ovarian torsion secondary to a cyst. They were operated on by conservative ovarian therapy regardless the time of evolution and ovary macroscopical aspect. These 2 patients were 9 and 13 years old, with abdominal colic pain of 48 and 36 hours of evolution. The diagnosis by doppler sonography was ovarian torsion, with a 4 cms cyst in the right ovary in the first case and a 5 cms cyst in the left ovary in the second patient. Both patients were operated on. After untwisting the ovary, we instille warm saline solution to this ovary and, after waiting for 10 minutes, we resect the ovarian cyst and it recuperates partial and heterogeneous its pink colour. We advise to the family about the possibility of surgical reintervention if the ovary is not viable. After 10 and 12 days of surgical intervention, the Doppler sonography has confirmed the existence of ovary flow and the symmetry of affected ovary in comparation to the opposite on. At the present, both patients are asymptomatic, with exhaustive ultrasound controls. Ovarian torsion is the most frequent complication of ovarian tumours of pediatrics (3-16%) and this is a real emergency in gynecology. Traditionally, it has been recommended the exeresis of ovarian torsion. Regardless the blue aspect of isquemic ovary affected by torsion and the time of evolution, in our experience when there is a minimal possibility of ovarian viability, it is possible to follow a conservative therapy because the macroscopical aspect of the ovary is not necessarily related with the following evolution of the case.
The Bravais Pendulum: The Distinct Charm of an Almost Forgotten Experiment
Babovic, V. M.; Mekic, S.
2011-01-01
In the year 1851 in Paris, the apparent change of the plane of oscillation of a linear pendulum was observed by Leon Foucault. In the same year, at the same place, the unequal duration of the oscillations of a right- and left-handed conical pendulum was observed by Bravais. Today, the Foucault pendula are common at universities, the Bravais…
Geometric numerical integration applied to the elastic pendulum at higher order resonance
Tuwankotta, J.M.; Quispel, G.R.W.
2000-01-01
In this paper we study the performance of a symplectic numerical integrator based on the splitting method This method is applied to a subtle problem ie higher order resonance of the elastic pendulum In order to numerically study the phase space of the elastic pendulum at higher order resonance a
Ivanenko, Yuri P; Dominici, Nadia; Cappellini, Germana; Dan, Bernard; Cheron, Guy; Lacquaniti, Francesco
2004-01-01
The inverted pendulum model in which the centre of mass of the body vaults over the stance leg in an arc represents a basic mechanism of bipedal walking. Is the pendulum mechanism innate, or is it learnt through walking experience? We studied eight toddlers (about 1 year old) at their first
Einstein versus the Simple Pendulum Formula: Does Gravity Slow All Clocks?
Puri, Avinash
2015-01-01
According to the Newtonian formula for a simple pendulum, the period of a pendulum is inversely proportional to the square root of "g", the gravitational field strength. Einstein's theory of general relativity leads to the result that time slows down where gravity is intense. The two claims look contradictory and can muddle student and…
On the Stable Limit Cycle of a Weight-Driven Pendulum Clock
Llibre, J; Teixeira, M. A.
2010-01-01
In a recent paper (Denny 2002 Eur. J. Phys. 23 449-58), entitled "The pendulum clock: a venerable dynamical system", Denny showed that in a first approximation the steady-state motion of a weight-driven pendulum clock is shown to be a stable limit cycle. He placed the problem in a historical context and obtained an approximate solution using the…
Mode competition in a system of two parametrically driven pendulums: te role of symmetry
Banning, E.J.; Banning, E.J.; van der Weele, J.P.; Kettenis, M.M.
1997-01-01
This paper is the final part in a series of four on the dynamics of two coupled, parametrically driven pendulums. In the previous three parts (Banning and van der Weele, Mode competition in a system of two parametrically driven pendulums; the Hamiltonian case, Physica A 220 (1995) 485¿533; Banning
Analysis of the Pendular and Pitch Motions of a Driven Three-Dimensional Pendulum
Findley, T.; Yoshida, S.; Norwood, D. P.
2007-01-01
A three-dimensional pendulum, modelled after the Laser Interferometer Gravitational-Wave Observatory's suspended optics, was constructed to investigate the pendulum's dynamics due to suspension point motion. In particular, we were interested in studying the pendular-pitch energy coupling. Determination of the pendular's Q value (the quality factor…
Analysis of Pendulum Period with an iPod Touch/iPhone
Briggle, Justin
2013-01-01
We describe the use of Apple's iPod touch/iPhone, acting as the pendulum bob, as a means of measuring pendulum period, making use of the device's three-axis digital accelerometer and the freely available SPARKvue app from PASCO scientific. The method can be readily incorporated into an introductory physics laboratory experiment.…
Using Excel to Simulate Pendulum Motion and Maybe Understand Calculus a Little Better
Fowler, Michael
2004-01-01
As part of a first-year college Introductory Physics course, I have students construct an Excel[R]: spreadsheet based on the differential equation for pendulum motion (we take a pendulum having a light bar rather than a string, so it can go "over the top"). In extensive discussions with the students, I find that forcing them to make the…
Barnes, Marianne B.; Garner, James; Reid, David
2004-01-01
In this article we use the pendulum as the vehicle for discussing the transition from classical to quantum physics. Since student knowledge of the classical pendulum can be generalized to all harmonic oscillators, we propose that a quantum analysis of the pendulum can lead students into the unanticipated consequences of quantum phenomena at the…
Adhitama, Egy; Fauzi, Ahmad
2018-01-01
In this study, a pendulum experimental tool with a light-based timer has been developed to measure the period of a simple pendulum. The obtained data was automatically recorded in an Excel spreadsheet. The intensity of monochromatic light, sensed by a 3DU5C phototransistor, dynamically changes as the pendulum swings. The changed intensity varies…
Foucault's Pendulum, Analog for an Electron Spin State
Linck, Rebecca
2012-11-01
The classical Lagrangian that describes the coupled oscillations of Foucault's pendulum presents an interesting analog to an electron's spin state in an external magnetic field. With a simple modification, this classical Lagrangian yields equations of motion that directly map onto the Schrodinger-Pauli Equation. This analog goes well beyond the geometric phase, reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.
Asymptotic shape of solutions to the perturbed simple pendulum problems
Directory of Open Access Journals (Sweden)
Tetsutaro Shibata
2007-05-01
Full Text Available We consider the positive solution of the perturbed simple pendulum problem $$ u''(r + frac{N-1}{r}u'(r - g(u(t + lambda sin u(r = 0, $$ with $0 < r < R$, $ u'(0 = u(R = 0$. To understand well the shape of the solution $u_lambda$ when $lambda gg 1$, we establish the leading and second terms of $Vert u_lambdaVert_q$ ($1 le q < infty$ with the estimate of third term as $lambda o infty$. We also obtain the asymptotic formula for $u_lambda'(R$ as $lambda o infty$.
Non-integrability of the generalized spring-pendulum problem
International Nuclear Information System (INIS)
Maciejewski, Andrzej J; Przybylska, Maria; Weil, Jacques-Arthur
2004-01-01
We investigate a generalization of the three-dimensional spring-pendulum system. The problem depends on two real parameters (k, a), where k is the Young modulus of the spring and a describes the nonlinearity of elastic forces. We show that this system is not integrable when k ≠ -a. We carefully investigated the case k = -a when the necessary condition for integrability given by the Morales-Ruiz-Ramis theory is satisfied. We discuss an application of the higher order variational equations for proving the non-integrability in this case
Design and Analysis of Controllers for an Double Inverted Pendulum
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Poulsen, Jesper Kildegaard
2005-01-01
A physical control problem is studied with the H_inf and the SSV methodology. The issues of modelling, uncertainty modelling, performance specification, controller design and laboratory implementation are discussed. The laboratory experiment is a double inverted pendulum placed on a cart....... The limitations in the system with respect to performance are the limitation in the control signal and the limitation of the movement of the cart. It is shown how these performance limitations will effect the design of H_inf and SSV controllers for the system....
Dynamic Analysis of a Pendulum Dynamic Automatic Balancer
Directory of Open Access Journals (Sweden)
Jin-Seung Sohn
2007-01-01
Full Text Available The automatic dynamic balancer is a device to reduce the vibration from unbalanced mass of rotors. Instead of considering prevailing ball automatic dynamic balancer, pendulum automatic dynamic balancer is analyzed. For the analysis of dynamic stability and behavior, the nonlinear equations of motion for a system are derived with respect to polar coordinates by the Lagrange's equations. The perturbation method is applied to investigate the dynamic behavior of the system around the equilibrium position. Based on the linearized equations, the dynamic stability of the system around the equilibrium positions is investigated by the eigenvalue analysis.
Robust sliding mode control applied to double Inverted pendulum system
International Nuclear Information System (INIS)
Mahjoub, Sonia; Derbel, Nabil; Mnif, Faical
2009-01-01
A three hierarchical sliding mode control is presented for a class of an underactuated system which can overcome the mismatched perturbations. The considered underactuated system is a double inverted pendulum (DIP), can be modeled by three subsystems. Such structure allows the construction of several designs of hierarchies for the controller. For all hierarchical designs, the asymptotic stability of every layer sliding mode surface and the sliding mode surface of subsystems are proved theoretically by Barbalat's lemma. Simulation results show the validity of these methods.
Humanoid Robot Balance Control using the Spherical Inverted Pendulum Model
Directory of Open Access Journals (Sweden)
Ahmed eElhasairi
2015-10-01
Full Text Available Human beings are highly efficient in maintaining standing balance under the influence of different perturbations. However, biped humanoid robots are far from exhibiting similar skills. This is mainly due to the limitations in the current control and modelling techniques used in humanoid robots. Even though approaches using the Linear Inverted Pendulum Model and the Preview Control schemes have shown improved results, they still suffer from shortcomings in the overall generated motion. We propose here a model and control approach that aims to overcome the limiting assumptions in the LIPM models, through using the ankle joint variables in modelling and control of the standing balance of the humanoid robot.
Investigation for Synchronization of a Rotor-Pendulum System considering the Multi-DOF Vibration
Directory of Open Access Journals (Sweden)
Yongjun Hou
2016-01-01
Full Text Available This work is a continuation for our published literature for vibration synchronization. A new mechanism, two rotors coupled with a pendulum rod in a multi-DOF vibration system, is proposed to implement coupling synchronization, and the dynamics equation of mechanism is derived by Lagrange equation. In addition, the coupling relationship between the vibrobody and the pendulum rod is ascertained with the Laplace transformation method, based on the dimensionless equation of the dynamics system. The Poincare method is employed to study the synchronization state between the two unbalanced rotors, which is converted into that of existence and the stability of solutions for synchronization-balance equations. The obtained results are supported by computer simulations. It is demonstrated that the values of the spring stiffness coefficient, the length of the pendulum, and the angular installation of the pendulum are important parameters with respect to the synchronous behavior in the rotor-pendulum system.
Multiple degree of freedom inverted pendulum dynamics: Modeling, computation, and experimentation
Chen, Cheng-Yuan Jerry
A pendulum is statically unstable in its upright inverted state due to the Earth's gravitational attraction which points downward. However, with proper forcing, the pendulum can be stabilized in its upright inverted state. Special interest is on periodic vertical forcing applied to the pendulum's base to stabilize it around the upright inverted equilibrium. Many researchers have studied how to stabilize the system by varying various parameters, in particular its amplitude and frequency. Most have focused on the single degree of freedom inverted pendulum case, which with linear assumption can be described via Mathieu's equation. The system stability can then be characterized by Floquet theory. Our focus is on searching for the periodic solutions inside the linearly stable region of the pendulum's inverted state when the pendulum is under proper periodic forcing. Our research shows that under appropriate excitation by controlling the forcing amplitude and frequency, the pendulum can maintain certain periodic orbits around its inverted state which we characterize in a systematic way. In this thesis, we applied four different kinds of geometric realizations of the system response: system time traces, system phase portraits, three dimensional views of the system phase portrait as a function of input forcing, and the system's power spectral density diagram. By analyzing these four diagrams simultaneously, we characterize different kinds of multi-frequency periodic behavior around the pendulum's inverted state. To further discuss the effect of the nonlinearity, we applied perturbation techniques using the normalized forcing amplitude as a perturbation parameter to carry out the approximate periodic solutions on a single degree of freedom inverted pendulum nonlinear model. We also discuss the multiple degree of freedom inverted pendulum system. Both numerical simulation and experiments were performed and detailed comparisons are discussed. Our numerical simulations show
Comparative distalization effects of Jones jig and pendulum appliances.
Patel, Mayara Paim; Janson, Guilherme; Henriques, José Fernando Castanha; de Almeida, Renato Rodrigues; de Freitas, Marcos Roberto; Pinzan, Arnaldo; de Freitas, Karina Maria Salvatore
2009-03-01
In this study, we compared the dentoalveolar changes of Class II patients treated with Jones jig and pendulum appliances. The experimental group comprised 40 Class II malocclusion subjects, divided into 2 groups: group 1 consisted of 20 patients (11 boys, 9 girls) at a mean pretreatment age of 13.17 years, treated with the Jones jig appliance for 0.91 years; group 2 comprised 20 patients (8 boys, 12 girls) at a mean pretreatment age of 13.98 years, treated with the pendulum appliance for 1.18 years. Only active treatment time of molar distalization was evaluated in the predistalization and postdistalization lateral cephalograms. Molar, second premolar, and incisor angular and linear variables were obtained. The intergroup treatment changes in these variables were compared with independent t tests. The maxillary second premolars showed greater mesial tipping and extrusion in the Jones jig group, indicating more anchorage loss during molar distalization with this appliance. The amounts and the monthly rates of molar distalization were similar in both groups. The Jones jig group showed greater mesial tipping and extrusion of the maxillary second premolars. The mean amounts and the monthly rates of first molar distalization were similar in both groups.
Singularities in Structural Optimization of the Ziegler Pendulum
Directory of Open Access Journals (Sweden)
O. N. Kirillov
2011-01-01
Full Text Available Structural optimization of non-conservative systems with respect to stability criteria is a research area with important applications in fluid-structure interactions, friction-induced instabilities, and civil engineering. In contrast to optimization of conservative systems where rigorously proven optimal solutions in buckling problems have been found, for nonconservative optimization problems only numerically optimized designs have been reported. The proof of optimality in non-conservative optimization problems is a mathematical challenge related to multiple eigenvalues, singularities in the stability domain, and non-convexity of the merit functional. We present here a study of optimal mass distribution in a classical Ziegler pendulum where local and global extrema can be found explicitly. In particular, for the undamped case, the two maxima of the critical flutter load correspond to a vanishing mass either in a joint or at the free end of the pendulum; in the minimum, the ratio of the masses is equal to the ratio of the stiffness coefficients. The role of the singularities on the stability boundary in the optimization is highlighted, and an extension to the damped case as well as to the case of higher degrees of freedom is discussed.
Torsion ratchet associated with mechanical hysteresis
International Nuclear Information System (INIS)
Han, S.; Wack, B.
1987-01-01
The experimental determination of behavior of material like metals, is often obtained with a tube shape sample. For the traction-compression and internal pressure test the direction of the solicitation principal axes is maintened constant. On the contrary the torsion test is a rotational solicitation and thus is accompagnied by secondary effects. For these reasons we conduct some cyclic torsion tests, with or without axial force, and attempt to measure as precisely as possible the axial deformation. The tests are run at a low strain rate and at room temperature so as to reduce as much as possible the influence of the viscosity phenomena and consequently to obtain results whose interpretation may be less complex. (orig./GL)
Torsion and transverse bending of cantilever plates
Reissner, Eric; Stein, Manuel
1951-01-01
The problem of combined bending and torsion of cantilever plates of variable thickness, such as might be considered for solid thin high-speed airplane or missile wings, is considered in this paper. The deflections of the plate are assumed to vary linearly across the chord; minimization of the potential energy by means of the calculus of variations then leads to two ordinary linear differential equations for the bending deflections and the twist of the plate. Because the cantilever is analyzed as a plate rather than as a beam, the effect of constraint against axial warping in torsion is inherently included. The application of this method to specific problems involving static deflection, vibration, and buckling of cantilever plates is presented. In the static-deflection problems, taper and sweep are considered.
Wang, Shibo; Niu, Chengchao
2016-01-01
In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T-θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model.
Wang, Shibo; Niu, Chengchao
2016-01-01
In this work, the plane-on-plane torsional fretting tribological behavior of polytetrafluoroethylene (PTFE) was studied. A model of a rigid, flat-ended punch acting on an elastic half-space was built according to the experimental conditions. The results indicate that the shape of T–θ curves was influenced by both the torsional angle and the normal load. The torsion friction torque and wear rate of PTFE exponentially decreased when the torsion angle rose. The torsional torque increased from 0.025 N·m under a normal load of 43 N to 0.082 N·m under a normal load of 123 N. With sequentially increasing normal load, the value of torque was maintained. With rising normal load, the wear mass loss of PTFE disks was increased and the wear rate was decreased. Good agreement was found with the calculated torque according to the model and the experimental torque except for that under a normal load of 163 N. The difference under a normal load of 163 N was caused by the coefficient of friction. Usually the coefficient of friction of a polymer decreases with increasing normal load, whereas a constant coefficient of friction was applied in the model. PMID:26799324
Torsional asymmetry in suspension bridge systems
Czech Academy of Sciences Publication Activity Database
Malík, Josef
2015-01-01
Roč. 60, č. 6 (2015), s. 677-701 ISSN 0862-7940 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : suspension bridge * Hamilton principle * vertical and torsional oscillation * uniqueness * existence Subject RIV: BA - General Mathematics Impact factor: 0.507, year: 2015 http://link.springer.com/article/10.1007%2Fs10492-015-0117-3
Torsion of a giant mesenteric lipoma
Energy Technology Data Exchange (ETDEWEB)
Wolko, Jonathan D.; Rosenfeld, David L.; Lazar, Michael J.; Underberg-Davis, Sharon J. [Department of Radiology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, P.O. Box 19, New Brunswick, NJ 08903-0019 (United States)
2003-01-01
Mesenteric lipoma is a rare benign neoplastic condition that can grow to be very large and mimic other midgut fatty tumors. These benign tumors can cause various gastrointestinal symptoms such as obstruction and abdominal pain. We report the case of a 9-year-old boy who presented with a small bowel obstruction caused by torsion of a large mesenteric lipoma. This is an important but unusual tumor and should be considered in the differential of fatty lesions within the mesentery. (orig.)
Electrostatically actuated torsional resonant sensors and switches
Younis, Mohammad I.
2016-12-29
Embodiments in accordance of a torsional resonant sensor disclosure is configured to actuate a beam structure using electrostatic actuation with an AC harmonic load (e.g., AC and DC voltage sources) that is activated upon detecting a particular agent having a mass above a predefined level. In various embodiments, the beam structure may be different types of resonant structures that is at least partially coated or layered with a selective material.
Spacetime thermodynamics in the presence of torsion
Dey, Ramit; Liberati, Stefano; Pranzetti, Daniele
2017-12-01
It was shown by Jacobson in 1995 that the Einstein equation can be derived as a local constitutive equation for an equilibrium spacetime thermodynamics. With the aim to understand if such thermodynamical description is an intrinsic property of gravitation, many attempts have been made so far to generalize this treatment to a broader class of gravitational theories. Here we consider the case of the Einstein-Cartan theory as a prototype of theories with nonpropagating torsion. In doing so, we study the properties of Killing horizons in the presence of torsion, establish the notion of local causal horizon in Riemann-Cartan spacetimes, and derive the generalized Raychaudhuri equation for these kinds of geometries. Then, starting with the entropy that can be associated to these local causal horizons, we derive the Einstein-Cartan equation by implementing the Clausius equation. We outline two ways of proceeding with the derivation depending on whether we take torsion as a geometric field or as a matter field. In both cases we need to add internal entropy production terms to the Clausius equation as the shear and twist cannot be taken to be 0 a priori for our setup. This fact implies the necessity of a nonequilibrium thermodynamics treatment for the local causal horizon. Furthermore, it implies that a nonzero twist at the horizon in general contributes to the Hartle-Hawking tidal heating for black holes with possible implications for future observations.
Isolated Penile Torsion in Brothers: A Case Report
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Metin Gunduz
2012-04-01
Full Text Available Penile torsion can be congenital and associated with hypospadias and chordee, or can be acquired after circumcision. The incidence of isolated neonatal penile torsion was 1.7 to 27% in the literature. The majority were between 10 and deg; and 20 and deg;. Generally, torsion was to the left in cases. The techniques for correction of penile torsion described in the literature are penile de-gloving and reattaching of skin, resection of Buck's fascia incising the base of the penis and removing angular ellipses of corporeal tissue with subsequent plication of tunica, and dorsal dartos flap rotation in severe cases. In conclusion, penile torsion may be familial. Therefore, brothers should be examined carefully. The degloving and realignment technique is successful in isolated penile torsion. [Arch Clin Exp Surg 2012; 1(2.000: 122-124
Fast Torsional Artificial Muscles from NiTi Twisted Yarns.
Mirvakili, Seyed M; Hunter, Ian W
2017-05-17
Torsional artificial muscles made of multiwalled carbon nanotube/niobium nanowire yarns have shown remarkable torsional speed and gravimetric torque. The muscle structure consists of a twisted yarn with half of its length infiltrated with a stimuli-responsive guest material such as paraffin wax. The volumetric expansion of the guest material creates the torsional actuation in the yarn. In the present work, we show that this type of actuation is not unique to wax-infiltrated carbon multiwalled nanotube (MWCNT) or niobium nanowire yarns and that twisted yarn of NiTi alloy fibers also produces fast torsional actuation. By gold-plating half the length of a NiTi twisted yarn and Joule heating it, we achieved a fully reversible torsional actuation of up to 16°/mm with peak torsional speed of 10 500 rpm and gravimetric torque of 8 N·m/kg. These results favorably compare to those of MWCNTs and niobium nanowire yarns.
Painless inter epididymal testicular torsion of the spermatic cord
Directory of Open Access Journals (Sweden)
Salomon V. Romano
2007-02-01
Full Text Available Inter epididymal testicular torsion of the spermatic cord is extremely rare and usually diagnosed at surgery. We present an unusual case of spermatic cord torsion in a 14-year-old male patient. It is important to highlight that the torsion occurred only on the distal half of the epididymis leaving the head untwisted and edematous. In addition, the fact that this condition was painless made this case extremely rare and motivated our presentation.
Painless inter epididymal testicular torsion of the spermatic cord
Salomon V. Romano; Haime S. Hernan; Norberto Fredotovich
2007-01-01
Inter epididymal testicular torsion of the spermatic cord is extremely rare and usually diagnosed at surgery. We present an unusual case of spermatic cord torsion in a 14-year-old male patient. It is important to highlight that the torsion occurred only on the distal half of the epididymis leaving the head untwisted and edematous. In addition, the fact that this condition was painless made this case extremely rare and motivated our presentation.
Secondary Torsion of Vermiform Appendix with Mucinous Cystadenoma
Maki Kitagawa; Tatsuya Kotani; Takeshi Yamano; Hideaki Tsurudome; Tomoya Hatakeyama; Yoshiaki Kuriu; Hiroshi Nishi; Masaharu Yabe
2007-01-01
Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis. We report a case (a 34-year-old male) of secondary torsion of the vermiform appendix with mucinous cystadenoma. This case was characterized by mild inflammatory responses, pentazocine-resistant abdominal pain, and appendiceal tumor, which was not enhanced by the contrast medium on computed tomography presumably because of reduced blood flow by the torsion. These fin...
An analytical solution to the equation of motion for the damped nonlinear pendulum
DEFF Research Database (Denmark)
Johannessen, Kim
2014-01-01
An analytical approximation of the solution to the differential equation describing the oscillations of the damped nonlinear pendulum at large angles is presented. The solution is expressed in terms of the Jacobi elliptic functions by including a parameter-dependent elliptic modulus. The analytical...... of the damped nonlinear pendulum is presented, and it is shown that the period of oscillation is dependent on time. It is established that, in general, the period is longer than that of a linearized model, asymptotically approaching the period of oscillation of a damped linear pendulum....
Multi-directional energy harvesting by piezoelectric cantilever-pendulum with internal resonance
Energy Technology Data Exchange (ETDEWEB)
Xu, J.; Tang, J., E-mail: jtang@engr.uconn.edu [Department of Mechanical Engineering, The University of Connecticut, Storrs, Connecticut 06269 (United States)
2015-11-23
This letter reports a piezoelectric cantilever-pendulum design for multi-directional energy harvesting. A pendulum is attached to the tip of a piezoelectric cantilever-type energy harvester. This design aims at taking advantage of the nonlinear coupling between the pendulum motion in 3-dimensional space and the beam bending vibration at resonances. Experimental studies indicate that, under properly chosen parameters, 1:2 internal resonance can be induced, which enables the multi-directional energy harvesting with a single cantilever. The advantages of the design with respect to traditional piezoelectric cantilever are examined.
Isolated fallopian tube torsion during pregnancy: a case report.
Lee, D H; Park, Y K
2015-01-01
Isolated fallopian tube torsion is a rare pregnancy-related complication. It is frequently misdiagnosed as acute appendicitis or ovarian torsion owing to the lack of specific symptoms or signs. Here, the authors report a case of a 35-year-old primigravida at 30 weeks and six days of gestation who had presented with right isolated fallopian tube torsion and a history of right oophorectomy. The authors propose that isolated fallopian tube torsion should be included in the list of differential diagnosis when encountered with patients complaining of lower abdominal pain.
Ultrasonographic features of prenatal testicular torsion: Case report
Directory of Open Access Journals (Sweden)
Elif Ağaçayak
2013-01-01
Full Text Available Although prenatal testicular torsion (PNTT is rarely observed,it is an important condition that can cause bilateralvanishing testis. Generally, PNTT cases observed asextravaginal torsion and treatment is emergency surgicalop-eration. In this article, 39 week presented a case diagnosedin the prenatal testicular torsion. PNTT diagnosiswas confirmed by Doppler ultrasonography and emergencysurgery was performed. Extravaginal left testiculartorsion gangrene and necrosis of the testis was observedin the operation. Left orchiectomy was performed andintrauter-ine ultrasonographic diagnosis was found to becorrect.Key words: Testicular torsion, prenatal diagnosis, features,ultrasonography
Secondary Torsion of Vermiform Appendix with Mucinous Cystadenoma
Directory of Open Access Journals (Sweden)
Maki Kitagawa
2007-06-01
Full Text Available Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis. We report a case (a 34-year-old male of secondary torsion of the vermiform appendix with mucinous cystadenoma. This case was characterized by mild inflammatory responses, pentazocine-resistant abdominal pain, and appendiceal tumor, which was not enhanced by the contrast medium on computed tomography presumably because of reduced blood flow by the torsion. These findings may be helpful for the preoperative diagnosis of secondary appendiceal torsion.
Torsion of vermiform appendix with fecalith: a case report
Wani, Imtiaz; Kitagawa, Maki; Rather, Mudasir; Singh, Jang; Bhat, Gulam; Nazir, Mir
2008-01-01
Introduction Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis and is found by chance during the laparotomy. Case presentation We report a case (a 76-year-old male) suffering of torsion of the vermiform appendix with fecalith. It was twisted 540 degrees in an anti-clockwise direction. Appendectomy was done. Conclusion Appendiceal torsion may be assocated with the presence of fecalith. This case is the oldest one among the patients with appendiceal torsion reported to literature. PMID:18577201
Secondary Torsion of Vermiform Appendix with Mucinous Cystadenoma
Kitagawa, Maki; Kotani, Tatsuya; Yamano, Takeshi; Tsurudome, Hideaki; Hatakeyama, Tomoya; Kuriu, Yoshiaki; Nishi, Hiroshi; Yabe, Masaharu
2007-01-01
Torsion of the vermiform appendix is a rare disorder, which causes abdominal symptoms indistinguishable from acute appendicitis. We report a case (a 34-year-old male) of secondary torsion of the vermiform appendix with mucinous cystadenoma. This case was characterized by mild inflammatory responses, pentazocine-resistant abdominal pain, and appendiceal tumor, which was not enhanced by the contrast medium on computed tomography presumably because of reduced blood flow by the torsion. These findings may be helpful for the preoperative diagnosis of secondary appendiceal torsion. PMID:21487469
Spherical Pendulum Small Oscillations for Slewing Crane Motion
Directory of Open Access Journals (Sweden)
Alexander V. Perig
2014-01-01
Full Text Available The present paper focuses on the Lagrange mechanics-based description of small oscillations of a spherical pendulum with a uniformly rotating suspension center. The analytical solution of the natural frequencies’ problem has been derived for the case of uniform rotation of a crane boom. The payload paths have been found in the inertial reference frame fixed on earth and in the noninertial reference frame, which is connected with the rotating crane boom. The numerical amplitude-frequency characteristics of the relative payload motion have been found. The mechanical interpretation of the terms in Lagrange equations has been outlined. The analytical expression and numerical estimation for cable tension force have been proposed. The numerical computational results, which correlate very accurately with the experimental observations, have been shown.
Application of the homotopy perturbation method to the nonlinear pendulum
International Nuclear Information System (INIS)
Belendez, A; Hernandez, A; Belendez, T; Neipp, C; Marquez, A
2007-01-01
The homotopy perturbation method is used to solve the nonlinear differential equation that governs the nonlinear oscillations of a simple pendulum, and an approximate expression for its period is obtained. Only one iteration leads to high accuracy of the solutions and the relative error for the approximate period is less than 2% for amplitudes as high as 130 0 . Another important point is that this method provides an analytical expression for the angular displacement as a function of time as the sum of an infinite number of harmonics; although for practical purposes it is sufficient to consider only a finite number of harmonics. We believe that the present study may be a suitable and fruitful exercise for teaching and better understanding perturbation techniques in advanced undergraduate courses on classical mechanics
Dynamical stability of a many-body Kapitza pendulum
Energy Technology Data Exchange (ETDEWEB)
Citro, Roberta, E-mail: citro@sa.infn.it [Dipartimento di Fisica “E. R. Caianiello” and Spin-CNR, Universita’ degli Studi di Salerno, Via Giovanni Paolo II, I-84084 Fisciano (Italy); Dalla Torre, Emanuele G., E-mail: emanuele.dalla-torre@biu.ac.il [Department of Physics, Bar Ilan University, Ramat Gan 5290002 (Israel); Department of Physics, Harvard University, Cambridge, MA 02138 (United States); D’Alessio, Luca [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Department of Physics, Boston University, Boston, MA 02215 (United States); Polkovnikov, Anatoli [Department of Physics, Boston University, Boston, MA 02215 (United States); Babadi, Mehrtash [Department of Physics, Harvard University, Cambridge, MA 02138 (United States); Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125 (United States); Oka, Takashi [Department of Applied Physics, University of Tokyo, Tokyo, 113-8656 (Japan); Demler, Eugene [Department of Physics, Harvard University, Cambridge, MA 02138 (United States)
2015-09-15
We consider a many-body generalization of the Kapitza pendulum: the periodically-driven sine–Gordon model. We show that this interacting system is dynamically stable to periodic drives with finite frequency and amplitude. This finding is in contrast to the common belief that periodically-driven unbounded interacting systems should always tend to an absorbing infinite-temperature state. The transition to an unstable absorbing state is described by a change in the sign of the kinetic term in the Floquet Hamiltonian and controlled by the short-wavelength degrees of freedom. We investigate the stability phase diagram through an analytic high-frequency expansion, a self-consistent variational approach, and a numeric semiclassical calculation. Classical and quantum experiments are proposed to verify the validity of our results.
Parameter Identification and Adaptive Control Applied to the Inverted Pendulum
Directory of Open Access Journals (Sweden)
Carlos A. Saldarriaga-Cortés
2012-06-01
Full Text Available This paper presents a methodology to implement an adaptive control of the inverted pendulum system; which uses the recursive square minimum method for the identification of a dynamic digital model of the plant and then, with its estimated parameters, tune in real time a pole placement control. The plant to be used is an unstable and nonlinear system. This fact, combined with the adaptive controller characteristics, allows the obtained results to be extended to a great variety of systems. The results show that the above methodology was implemented satisfactorily in terms of estimation, stability and control of such a system. It was established that adaptive techniques have a proper performance even in systems with complex features such as nonlinearity and instability.
Effects of ionizing radiation on Capsicum baccatum var. pendulum (Solanaceae)
International Nuclear Information System (INIS)
Scaldaferro, M.A.; Prina, A.R.; Moscone, E.A.; Kwasniewska, J.
2013-01-01
Cytogenetic and somatic effects of various x-ray treatments were evaluated in pepper, Capsicum baccatum var. pendulum cv. “Cayenne”, with the aim to assess optimal conditions for obtaining viable lines. The cytogenetic effects were quantified by counting chromosome aberrations. The level of DNA fragmentation was estimated with TUNEL test (terminal transferase mediated dUTP-fluorescein nick end labeling). Irradiation to 20 Gy with 16-h presoaking can be a suitable treatment of the selected pepper cultivar for a mutagenesis program. - Highlights: • Cytogenetic and somatic effects of x-rays treatments in Capsicum were evaluated. • Frequencies of chromosome aberrations correlated with radiation doses. • Highest frequency of chromosome aberrations occurred with 20 Gy+soaking seeds. • In TUNEL test, the nuclei with DNA fragmentation were higher than in the control. • The strongest effects were observed with doses of 300 Gy or 20 Gy after soaking
Passive Fault tolerant Control of an Inverted Double Pendulum
DEFF Research Database (Denmark)
Niemann, H.; Stoustrup, Jakob
2003-01-01
A passive fault tolerant control scheme is suggested, in which a nominal controller is augmented with an additional block, which guarantees stability and performance after the occurrence of a fault. The method is based on the Youla parameterization, which requires the nominal controller to be imp...... to be implemented in the observer based form. The proposed method is applied to a double inverted pendulum system, for which an H controller has been designed and verified in a lap setup. In this case study, the fault is a degradation of the tacho loop.......A passive fault tolerant control scheme is suggested, in which a nominal controller is augmented with an additional block, which guarantees stability and performance after the occurrence of a fault. The method is based on the Youla parameterization, which requires the nominal controller...
Accuracy evaluation of pendulum gravity measurements of Robert von Sterneck
Directory of Open Access Journals (Sweden)
Alena Pešková
2015-06-01
Full Text Available The accuracy of first pendulum gravity measurements in the Czech territory was determined using both original surveying notebooks of Robert Daublebsky von Sterneck and modern technologies. Since more accurate methods are used for gravity measurements nowadays, our work is mostly important from the historical point of view. In previous works, the accuracy of Sterneck’s gravity measurements was determined using only a small dataset. Here we process all Sterneck’s measurements from the Czech territory (a dataset ten times larger than in the previous works, and we complexly assess the accuracy of these measurements. Locations of the measurements were found with the help of original notebooks. Gravity in the site was interpolated using actual gravity models. Finally, the accuracy of Sterneck’s measurements was evaluated as the difference between the measured and interpolated gravity.
Fibroma de Vulva (Molluscum Pendulum): Relato de Caso
Netto,Alfredo Roberto; Focchi,Gustavo Rubino de Azevedo; Ribalta,Julisa Chamorro Lascasas; Giannotti Filho,Osvaldo; Focchi,José; Baracat,Edmund Chada
2001-01-01
É apresentado um caso de fibroma de vulva, modalidade molluscum pendulum, em uma jovem de 20 anos. O tumor desenvolveu-se após a menarca com evolução lenta e progressiva. Ao exame físico, observou-se volumosa massa pediculada, indolor, com inserção no terço superior do grande lábio esquerdo, de consistência elástica, com diâmetro maior em sua parte distal de 12 cm por 23 cm de comprimento. Como tratamento, optou-se pela exérese pela base do pedículo, sob anestesia local. O tumor apresentou o ...
Parameter Estimation of Damped Compound Pendulum Differential Evolution Algorithm
Directory of Open Access Journals (Sweden)
Saad Mohd Sazli
2016-01-01
Full Text Available This paper present the parameter identification of damped compound pendulum using differential evolution algorithm. The procedure used to achieve the parameter identification of the experimental system consisted of input output data collection, ARX model order selection and parameter estimation using conventional method least square (LS and differential evolution (DE algorithm. PRBS signal is used to be input signal to regulate the motor speed. Whereas, the output signal is taken from position sensor. Both, input and output data is used to estimate the parameter of the ARX model. The residual error between the actual and predicted output responses of the models is validated using mean squares error (MSE. Analysis showed that, MSE value for LS is 0.0026 and MSE value for DE is 3.6601×10-5. Based results obtained, it was found that DE have lower MSE than the LS method.
Parameter Estimation of Damped Compound Pendulum Using Bat Algorithm
Directory of Open Access Journals (Sweden)
Saad Mohd Sazli
2016-01-01
Full Text Available In this study, the parameter identification of the damped compound pendulum system is proposed using one of the most promising nature inspired algorithms which is Bat Algorithm (BA. The procedure used to achieve the parameter identification of the experimental system consists of input-output data collection, ARX model order selection and parameter estimation using bat algorithm (BA method. PRBS signal is used as an input signal to regulate the motor speed. Whereas, the output signal is taken from position sensor. Both, input and output data is used to estimate the parameter of the autoregressive with exogenous input (ARX model. The performance of the model is validated using mean squares error (MSE between the actual and predicted output responses of the models. Finally, comparative study is conducted between BA and the conventional estimation method (i.e. Least Square. Based on the results obtained, MSE produce from Bat Algorithm (BA is outperformed the Least Square (LS method.
Torsional superelasticity of NiTi archwires.
Bolender, Yves; Vernière, Anne; Rapin, Christophe; Filleul, Marie-Pierryle
2010-11-01
To reproduce and compare the intraoral torsional behavior of 10 commonly used preformed upper NiTi 0.017 x 0.025 archwires in 0.018-slot brackets at 20 degrees C, 35 degrees C, and 55 degrees C. Ten upper preformed NiTi archwires were compared to a multibraided stainless steel wire. An original testing bench was used to reproduce palatal root torque applied onto an upper central incisor with a maximum value of 1540 g x mm. Ten samples of each wire type were tested at 20 degrees C, 35 degrees C, and 55 degrees C each. Loading and unloading at 20 degrees C revealed three categories of wires: a group of four NiTi wires of relative stiffness bereft of any superelasticity, a group of six NiTi wires displaying some horizontal plateau, and finally the stainless steel wire of lesser stiffness. Testing at the average oral temperature of 35 degrees C produced the same three categories of wires, with only 2 of 10 NiTi wires displaying a superelastic effect (Copper NiTi 35 degrees C and 40 degrees C). None of the NiTi wires was superelastic at 55 degrees C. Moments increased with temperature as the martensite was replaced by the more rigid austenite. This study showed that most NiTi wires did not exhibit in torsion the superelastic effect traditionally described in bending. The combination of straight-wire prescriptions and rectangular superelastic NiTi archwires did not provide optimal constant moments necessary to gain third-order control of tooth movement early in treatment. A braided stainless steel rectangular archwire displayed better torsional behavior at 35 degrees C than most NiTi archwires of the same dimensions.
Toward laboratory torsional spine magnetic reconnection
Chesny, David L.; Orange, N. Brice; Oluseyi, Hakeem M.; Valletta, David R.
2017-12-01
Magnetic reconnection is a fundamental energy conversion mechanism in nature. Major attempts to study this process in controlled settings on Earth have largely been limited to reproducing approximately two-dimensional (2-D) reconnection dynamics. Other experiments describing reconnection near three-dimensional null points are non-driven, and do not induce any of the 3-D modes of spine fan, torsional fan or torsional spine reconnection. In order to study these important 3-D modes observed in astrophysical plasmas (e.g. the solar atmosphere), laboratory set-ups must be designed to induce driven reconnection about an isolated magnetic null point. As such, we consider the limited range of fundamental resistive magnetohydrodynamic (MHD) and kinetic parameters of dynamic laboratory plasmas that are necessary to induce the torsional spine reconnection (TSR) mode characterized by a driven rotational slippage of field lines - a feature that has yet to be achieved in operational laboratory magnetic reconnection experiments. Leveraging existing reconnection models, we show that within a 3$ apparatus, TSR can be achieved in dense plasma regimes ( 24~\\text{m}-3$ ) in magnetic fields of -1~\\text{T}$ . We find that MHD and kinetic parameters predict reconnection in thin current sheets on time scales of . While these plasma regimes may not explicitly replicate the plasma parameters of observed astrophysical phenomena, studying the dynamics of the TSR mode within achievable set-ups signifies an important step in understanding the fundamentals of driven 3-D magnetic reconnection and the self-organization of current sheets. Explicit control of this reconnection mode may have implications for understanding particle acceleration in astrophysical environments, and may even have practical applications to fields such as spacecraft propulsion.
Transverse posterior element fractures associated with torsion
International Nuclear Information System (INIS)
Abel, M.S.
1989-01-01
Six examples of a previously undescribed class of transverse vertebral element fractures are presented. These fractures differ from Chance and Smith fractures and their variants in the following respects: (1) the etiology is torsion and not flexion; (2) there is neither distraction of posterior ring fragments nor posterior ligament tears; (3) in contrast to Chance and Smith fractures, extension of the fracture into the vertebral body is absent or minimal; (4) the transverse process of the lumbar vertebra is avulsed at its base with a vertical fracture, not split horizontally. These fractures occur in cervical, lumbar, and sacral vertebrae in normal or compromised areas of the spine. (orig.)
Possible role of torsion in gravitational theories
International Nuclear Information System (INIS)
Nieh, H.T.
1983-01-01
Torsion is of interest in an indirect way, in that it has the potential of being an important ingredient in a future successful quantum theory of gravitation. Einstein's theory of gravitation, despite its simplicity and elegance, and its successes in large-scale gravitational phenomena, can only be regarded as a macroscopic classical theory. It is a non-renormalizable quantum field theory, and, therefore, lacks the status of a good microscopic theory. It is the search for a successful quantum field theory of gravitation that poses as one of the great challenges to theoretical physics today. (Auth.)
Analogy between dynamics of thermo-rheological and piezo-rheological pendulums
Energy Technology Data Exchange (ETDEWEB)
Hedrih, K [Faculty of Mechanical Engineering University of Nis, Mathematical Institute SANU, ul. Vojvode Tankosic 3/V/22, 18000-Nis (Serbia)], E-mail: katica@masfak.ni.ac.yu, E-mail: khedrih@eunet.yu
2008-02-15
The constitutive stress-strain relations of the standard thermo-rheological and piezo-rheological hereditary element in differential form as well as in two different integro-differential forms are defined. The considered problem of a thermo-rheological hereditary discrete system nonlinear dynamics in the form of thermo-rheological double pendulum system with coupled pendulums gets the significance of two constrained bodies in plane motion problem, as a problem important for studying a sensor dynamics or actuator dynamics in active structure dynamics. System of the averaged equations in the first approximation for amplitudes and phases are derived and qualitatively analyzed. Analogy between nonlinear dynamics of the double pendulum systems with thermo-rheological and piezo-rheological properties between pendulums is pointed out.
Analogy between dynamics of thermo-rheological and piezo-rheological pendulums
International Nuclear Information System (INIS)
Hedrih, K
2008-01-01
The constitutive stress-strain relations of the standard thermo-rheological and piezo-rheological hereditary element in differential form as well as in two different integro-differential forms are defined. The considered problem of a thermo-rheological hereditary discrete system nonlinear dynamics in the form of thermo-rheological double pendulum system with coupled pendulums gets the significance of two constrained bodies in plane motion problem, as a problem important for studying a sensor dynamics or actuator dynamics in active structure dynamics. System of the averaged equations in the first approximation for amplitudes and phases are derived and qualitatively analyzed. Analogy between nonlinear dynamics of the double pendulum systems with thermo-rheological and piezo-rheological properties between pendulums is pointed out
Mathematical Modeling of a Moving Planar Payload Pendulum on Flexible Portal Framework
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Edwar Yazid
2012-03-01
Full Text Available Mathematical modeling of a moving planar payload pendulum on elastic portal framework is presented in this paper. The equations of motion of such a system are obtained by modeling the portal frame using finite element in conjunction with moving finite element method and moving planar payload pendulum by using Lagrange’s equations. The generated equations indicate the presence of nonlinear coupling between dynamics of portal framework and the payload pendulum. The combinational direct numerical integration technique, namely Newmarkand fourth-order Runge-Kutta method, is then proposed to solve the coupled equations of motion. Several numerical simulations are performed and the results are verified with several benchmarks. The results indicate that the amplitude and frequency of the payload pendulum swing angle are greatly affected by flexibility of structure and the cable in term of carriage speed.
The Bravais pendulum: the distinct charm of an almost forgotten experiment
International Nuclear Information System (INIS)
Babovic, V M; Mekic, S
2011-01-01
In the year 1851 in Paris, the apparent change of the plane of oscillation of a linear pendulum was observed by Leon Foucault. In the same year, at the same place, the unequal duration of the oscillations of a right- and left-handed conical pendulum was observed by Bravais. Today, the Foucault pendula are common at universities, the Bravais pendula not at all. We have revisited and experimentally tested Bravais's method and found it worthy of revitalization in student labs.
Monika Koul; Ayushi Singla; Anil Singla; Vivek Mahajan; Harupinder Singh Jaj; Priyanka Negi
2017-01-01
Introduction: The purpose of this prospective study was to analyze the efficiency of pendulum appliance for distalizing maxillary first molar while decreasing the anchorage loss by banding first and second premolar and making them one unit. Materials and Methods: The study group comprised of 20 patients (mean age 13 ± 2 years) who had skeletal Class I and Angle's Class II molar relation. Modified pendulum appliance was given to distalize maxillary first molar and to decrease the anchorage los...
Correlation of severity of penile torsion with type of hypospadias ...
African Journals Online (AJOL)
Objective: This study was carried out to evaluate the correlation between the severity of penile torsion on the one hand and the degree of ventral penile curvature and the type of hypospadias on the other. We also assessed the effectiveness of correction of chordee and torsion by penile degloving and mobilization of the ...
Perinatal testicular torsion: literature review and local experience ...
African Journals Online (AJOL)
The prognosis in TUDT is guarded and contralateral fixation was not practiced, except in a 5-week-old infant. Early orchiopexy at 3–6 months is recommended. Cooperation between surgeons, neonatologists, and parents is mandatory to avoid time delay. Keywords: intrauterine testicular torsion, postnatal testicular torsion, ...
Torsion of the Spermatic Cord: Is Bilateral Orchidopexy Really ...
African Journals Online (AJOL)
Aim: To evaluate the rationale for bilateral orchidopexy as treatment for unilateral torsion of the testis, by determining how frequently the contralateral testis shows an abnormal pathology in unilateral testicular torsion. Patients and Methods:This is a retrospective study using adult urology patients treated for both acute and ...
experimental and analytical comparison of torsion, bending moment
African Journals Online (AJOL)
HOD
by shear design. Less attention was paid in the past by reinforced concrete designers to these effects of torsion in reinforced concrete members. When torsion is encountered in reinforced ... and composite nature of the material and presence of cracks [2]. .... principles and some limited design equations for a generalized ...
Penile Torsion: an Overlooked Anomaly with Distal Hypospadias
African Journals Online (AJOL)
HussamHassan
with posterior hypospadias had associating penile torsion. Follow-up showed satisfactory correction of penile torsion in 3 out of 9 patients in group A; and in 8 out of ... using MillenMed DICOM viewer program for image analysis, based on the orientation of the urethral groove (meatus) relative to the vertical position (fig. B). P ...
A Patient Presenting with Concurrent Testis Torsion and Epididymal Leiomyoma
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E. Arpali
2013-01-01
Full Text Available Leiomyomas are the second most common tumors of epididymis. Patients with leiomyomas are sometimes misdiagnosed with testicular tumors. A Case of a patient with a scrotal mass presenting with testicular torsion is reported. Concurrent occurrence of testicular torsion and epididymal leiomyoma is an extremely rare condition.
Torsion of right middle lobe after a right upper lobectomy
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Chen Tung-Ying
2009-04-01
Full Text Available Abstract Lobar torsion after lung resection is a quite rare complication. A 50-year-old woman presented typical features on chest radiographs and CT(computed tomography scan of lobar torsion after a right upper lobectomy. After emergency lobectomy of right middle lobe, the patient recovered well and discharged 10 days after the second operation.
Torsional Strengthening of RC Beams Using GFRP Composites
Patel, Paresh V.; Jariwala, Vishnu H.; Purohit, Sharadkumar P.
2016-09-01
Fiber reinforced polymer as an external reinforcement is used extensively for axial, flexural and shear strengthening in structural systems. The strengthening of members subjected to torsion is recently being explored. The loading mechanism of beams located at the perimeter of buildings which carry loads from slabs, joists and beams from one side of the member generates torsion that are transferred from the beams to the columns. In this work an experimental investigation on the improvement of the torsional resistance of reinforced concrete beams using Glass Fiber Reinforced Polymer (GFRP) is presented. Total 24 RC beams have been cast in this work. Ten beams of dimension 150 mm × 150 mm × 1300 mm are subjected to pure torsion while fourteen beams of 150 mm × 150 mm × 1700 mm are subjected to combined torsion and bending. Two beams in each category are designated as control specimen and remaining beams are strengthened by GFRP wrapping of different configurations. Pure torsion on specimens is applied using specially fabricated support mechanism and universal testing machine. For applying combined torsion and bending a loading frame and test set up are fabricated. Measurements of angle of twist at regular interval of torque, torsion at first crack, and ultimate torque, are obtained for all specimens. Results of different wrapping configurations are compared for control and strengthened beams to suggest effective GFRP wrapping configuration.
Prediction of Torsional Strength for Very High Early Strength Geopolymer
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Woraphot PRACHASAREE
2017-11-01
Full Text Available Very early high strength geopolymers are gaining acceptance as alternative repair materials for highways and other infrastructure. In this study, a very rapid geopolymer binder based on Metakaolin (MK and Parawood ash (PWA, developed by the authors, was experimentally tested and a prediction model for its torsional strength is proposed. The geopolymer samples were subjected to uniaxial compression, flexural beam, and torsion tests. The modulus of rupture and torsional strength in terms of compression strength were found to be well approximated by 0.7(f’c1/2 and 1/7(x2y (f’c1/2, respectively. Also an interaction relation to describe combined bending and torsion was developed in this study. In addition, the effects of aspect ratio (y/x were studied on both torsional strength and combined bending and torsion. It was found that an aspect ratio of y/x = 3 significantly reduced the torsional resistance, to about 50 % of the torsional strength of a square section.DOI: http://dx.doi.org/10.5755/j01.ms.23.4.17280
Mechanical origins of rightward torsion in early chick brain development
Chen, Zi; Guo, Qiaohang; Dai, Eric; Taber, Larry
2015-03-01
During early development, the neural tube of the chick embryo undergoes a combination of progressive ventral bending and rightward torsion. This torsional deformation is one of the major organ-level left-right asymmetry events in development. Previous studies suggested that bending is mainly due to differential growth, however, the mechanism for torsion remains poorly understood. Since the heart almost always loops rightwards that the brain twists, researchers have speculated that heart looping affects the direction of brain torsion. However, direct evidence is lacking, nor is the mechanical origin of such torsion understood. In our study, experimental perturbations show that the bending and torsional deformations in the brain are coupled and that the vitelline membrane applies an external load necessary for torsion to occur. Moreover, the asymmetry of the looping heart gives rise to the chirality of the twisted brain. A computational model and a 3D printed physical model are employed to help interpret these findings. Our work clarifies the mechanical origins of brain torsion and the associated left-right asymmetry, and further reveals that the asymmetric development in one organ can induce the asymmetry of another developing organ through mechanics, reminiscent of D'Arcy Thompson's view of biological form as ``diagram of forces''. Z.C. is supported by the Society in Science - Branco Weiss fellowship, administered by ETH Zurich. L.A.T acknowledges the support from NIH Grants R01 GM075200 and R01 NS070918.
Torsion of the Spermatic Cord: An Exemplary Early Presentation ...
African Journals Online (AJOL)
... still the norm. In the index patient, the presentation time was very short. In our environment, patients with torsion of the spermatic cord can present early and be operated promptly if we can provide public health education, mobile phones, commercial taxis, and good road networks. Keywords: Spermatic cord, testis, torsion ...
Manual Detorsion of Testicular Torsion - A Primary Care Intervention ...
African Journals Online (AJOL)
Testicular torsion is one of the known acute urological emergencies that require prompt intervention. Salvage of the testis is only possible if derotation is performed within 6 hours of onset of symptoms. The objective of this paper is to report successful manual detorsion of the testes of patients with testicular torsion.
Effect of irregularity on torsional surface waves in an initially ...
Indian Academy of Sciences (India)
Effect of irregularity on torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half- ... Torsional wave; anisotropy; initial stress; irregularity; non-homogeneity ... Department of Applied Mathematics, Indian School of Mines, Dhanbad 826 004, India.
Case series on testicular torsion: an educational emergency for sub ...
African Journals Online (AJOL)
305 records ... Testicular torsion remains a common surgical emergency of adolescent males presenting with sudden onset of intense scrotal pain in Africa. While the magnitude of testicular torsion is not known it has been identified as a cause of male infertility. Testicular loss in Africa is directly related to delay in surgery and ...
CONSTRAINING SPACETIME TORSION WITH THE MOON, MERCURY AND LAGEOS
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Riccardo March
2013-12-01
Full Text Available We consider an extension of Einstein General Relativity where, beside the Riemann curvature tensor, we suppose the presence of a torsion tensor. Using a parametrized theory based on symmetry arguments, we report on some results concerning the constraints that can be put on torsion parameters by studying the orbits of a test body in the solar system.
Severe congenital penile torsion with anterior urethral diverticulum ...
African Journals Online (AJOL)
On examination, he was found to be a case of severe congenital penile torsion with diversion and rotation of median raphae in a counterclockwise fashion upto the midline dorsally confirming 180◦ torsion. During voiding, there was appearance of a swelling in distal penile region with passage of urinary drops while ...
Intermittent Testicular Torsion | Obi | Nigerian Journal of Clinical ...
African Journals Online (AJOL)
Methods: Clinical and demographic data of all patients treated for intermittent testicular torsion from January 2007 to June 2015 were prospectively collected in a pro forma and analyzed. A diagnosis of intermittent torsion was made on the basis of recurrent scrotal pain, presence of abnormal testicular lie in otherwise normal ...
Primary omental torsion in children: case report | Khalid | Pan ...
African Journals Online (AJOL)
Primary omental torsion in children: case report. Khattala Khalid, Tenorkorang Snr Somuah, Elmadi Aziz, Rami Mohamed, Bouabdallah Youssef. Abstract. Primary omental torsion is a rare cause of acute abdominal pain, we report a case of 10-year-old boy admitted with crampy abdominal pain, routine laboratory tests and ...
Pendulum Test: A Highly Accurate and Simple Physical Examination Maneuver to Identify Hip Pathology
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Yasushi Oshima
2015-10-01
Full Text Available Background: Patients with hip pathology often complain of various symptoms, e.g. pain or discomfort of low back, lower extremity, hip, groin, thigh, buttock or knee. Physicians may be distracted by these complaints, and misdiagnose and mistreat hip pathology. To avoid this, the pendulum test, which is performed with a patient seated on the examination table and hips and knees are flexed at 90 degrees, while the examiner passively swings the patient's lower extremity in and out as a pendulum, has been employed for all patients with the complaint of low back, hip and knee. Objective: The efficacy and the accuracy of the pendulum test were evaluated. Patients and methods: Consecutive 40 patients, who had complained pain or discomfort of low back, lower extremity, hip, groin, thigh, buttock and knee were examined by the pendulum test. Results: Eighteen patients were positive for the pendulum test, and all of them correlated to the hip pathology. Conclusions: The pendulum test was confirmed to be easily performed and reliable in detecting the hip pathology. Therefore, this test is highly recommended for the differentiation of patients with low back, hip and knee complaints.
Container Shipping Network Efficiency Comparison in Indonesia: Nusantara Pendulum and Sea Tollway
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Hafida Fahmiasari
2017-07-01
Full Text Available The disparity of the trading activities in Indonesia has triggered Indonesia Port Corporation to come up with the plan of Nusantara Pendulum, the future network of container shipping in Indonesia. The Sea Tollway plan is the modification of Nusantara Pendulum that is also envisioned by Indonesia President for Indonesia future backbone container plan. Both networks were designed to increase Indonesia container shipping flow from west to east and vice versa like a pendulum, thus results the reduced transport cost. This paper depicts the comparison of network efficiency analysis between these networks: Nusantara Pendulum, Sea Tollway, and the existing network. Two main methods that are used are Nagurney-Qiang and Jenelius-Peterson-Mattson. Mainly, these two methods use the efficiency calculation by considering parameters of demand (goods flow between each region and maritime transportation cost. It is concluded afterward that: 1 Sea Tollway is 8% more efficient than Nusantara Pendulum; 2 Sea Tollway and Nusantara Pendulum are ten times more efficient than current network; 3 Eastern ports in Indonesia (Bitung and Sorong urgently requisite a development.
Turbulence Modeling of Torsional Couette Flows
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Sofia Haddadi
2008-01-01
Full Text Available The present study considers the numerical modeling of the turbulent flow inside a rotor-stator cavity subjected or not to a superimposed throughflow. Extensive numerical predictions based on one-point statistical modeling using a low Reynolds number second-order full stress transport closure (RSM model are performed mainly in the case of turbulent flows with merged boundary layers known as turbulent torsional Couette flows and belonging to regime III of Daily and Nece (1960. The RSM model has already shown its capability of predicting accurately the mean and turbulent fields in various rotating disk configurations (Poncet, 2005; Poncet et al., 2005, 2007, 2008. For the first time, a detailed mapping of the hydrodynamic flow over a wide range of rotational Reynolds numbers (180 000≤Re≤10 000 000, aspect ratios of the cavity (0.02≤G≤0.05, and flow rate coefficients (−10000≤Cw≤10000 is here provided in the turbulent torsional Couette flow regime.
Lung lobe torsion in seven juvenile dogs.
Latimer, Christian R; Lux, Cassie N; Sutton, Jessie S; Culp, William T N
2017-12-15
CASE DESCRIPTION 7 juvenile (< 12 months old) dogs with lung lobe torsion were evaluated. CLINICAL FINDINGS All patients were male; breeds included Pug (n = 5), Chinese Shar-Pei (1), and Bullmastiff (1). Dyspnea and lethargy were the most common initial complaints, with a duration of clinical signs ranging from 1 to 10 days. A CBC showed leukocytosis and neutrophilia in all dogs. Anemia was present in 6 dogs, 2 of which received packed RBC transfusions. The diagnosis was made on the basis of results of thoracic radiography, CT, ultrasonography, or a combination of modalities. The left cranial lung lobe was most commonly affected (n = 4), followed by the right middle lung lobe (2) and the right cranial lung lobe (1). TREATMENT AND OUTCOME A lateral intercostal thoracotomy with lobectomy of the affected lobe was performed in all patients. All dogs survived to be discharged between 1 and 2 days postoperatively. Six of 7 owners contacted for follow-up information 7 to 170 months after discharge reported satisfaction with the treatment and no apparent signs of recurrence of disease. CLINICAL RELEVANCE The juvenile patients of this report were successfully treated surgically with no apparent complications. Clinicians should be aware of the possibility of lung lobe torsion when evaluating young dogs with clinical signs related to the respiratory system, including those with vague signs, to avoid undue delays in treatment.
The Reidemeister torsion of 3-manifolds
Nicolaescu, Liviu I
2003-01-01
This is a state-of-the-art introduction to the work of Franz Reidemeister, Meng Taubes, Turaev, and the author on the concept of torsion and its generalizations. Torsion is the oldest topological (but not with respect to homotopy) invariant that in its almost eight decades of existence has been at the center of many important and surprising discoveries. During the past decade, in the work of Vladimir Turaev, new points of view have emerged, which turned out to be the "right ones" as far as gauge theory is concerned. The book features mostly the new aspects of this venerable concept. The theoretical foundations of this subject are presented in a style accessible to those, who wish to learn and understand the main ideas of the theory. Particular emphasis is upon the many and rather diverse concrete examples and techniques which capture the subleties of the theory better than any abstract general result. Many of these examples and techniques never appeared in print before, and their choice is often justified by ...
Krukenberg Tumor: A Rare Cause of Ovarian Torsion
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Sameer Sandhu
2012-01-01
Full Text Available Ovarian torsion is the fifth most common gynecological surgical emergency. Ovarian torsion is usually associated with a cyst or a tumor, which is typically benign. The most common is mature cystic teratoma. We report the case of a 43-year-old woman who came to the Emergency Department with rare acute presentation of bilateral Krukenberg tumors, due to unilateral ovarian torsion. In this case report, we highlight the specific computed tomography (CT features of ovarian torsion and demonstrate the unique radiological findings on CT imaging. Metastasis to the ovary is not rare and 5 to 10% of all ovarian malignancies are metastatic. The stomach is the common primary site in most Krukenberg tumors (70%; an acute presentation of metastatic Krukenberg tumors with ovarian torsion is rare and not previously reported in radiology literature.
Physics of detecting torsion and placing limits on its effects
International Nuclear Information System (INIS)
Stoeger, W.R.
1985-01-01
The essential principles of torsion-detection physics are presented, and an evaluation is conducted of several conceivable types of experiments and observations for actually detecting torsion fields, reemphasizing also the evident impossibility of successfully searching for its manifestations among cosmological relics. In particular, a polarized body, with net intrinsic (fundamental-particle) spin, is essential for detecting a torsion field. One which possesses only orbital angular momentum - rotation - or an unpolarized intrinsic spin density will not feel torsion. The fundamental problem in searching for such fields is the extremely small basic unit of the coupling or interaction energy between the torsion field and spin. The best way of maximizing the total interaction energy is to increase the spin density of the source sigma-s and at the same time the spin number SD of the detector. 15 references
COJOCARU Vasile; CACAREAZA Gabriel
2016-01-01
The laboratory equipment used for testing the impact behavior of plastics uses low impact energies. In the last years were developed constructive solutions of monobloc pendulums, in order to ensure design and manufacturing simplicity. The paper presents the possibilities of optimizing a 15 J pendulum using 3D CAD design and finite element analysis. It highlights the possibilities for quick determination of the pendulum inertial properties ensuring the correlation between the position of mass ...
Directory of Open Access Journals (Sweden)
G. Peláez
2007-01-01
Full Text Available An investigation of the response of a physical pendulum to time delay filtered inputs was conducted. It was shown that the physical pendulum model is more accurate than the simple pendulum for modelling the dynamic response of overhead cranes with loads hanging from hooks. Based on the physical pendulum model a Specified Time Delay filter for an experimental mini overhead crane was synthesized. While somewhat limited in the scope by the hardware conditions placed in the system, the results provide basic insights into the successful application of the Time Delay Filtering method to overhead cranes.
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COJOCARU Vasile
2016-11-01
Full Text Available The laboratory equipment used for testing the impact behavior of plastics uses low impact energies. In the last years were developed constructive solutions of monobloc pendulums, in order to ensure design and manufacturing simplicity. The paper presents the possibilities of optimizing a 15 J pendulum using 3D CAD design and finite element analysis. It highlights the possibilities for quick determination of the pendulum inertial properties ensuring the correlation between the position of mass center and the position of impact center of pendulum. A finite element analysis of maximum stress and displacement was performed correlated with the study of inertial properties.
Adhitama, Egy; Fauzi, Ahmad
2018-05-01
In this study, a pendulum experimental tool with a light-based timer has been developed to measure the period of a simple pendulum. The obtained data was automatically recorded in an Excel spreadsheet. The intensity of monochromatic light, sensed by a 3DU5C phototransistor, dynamically changes as the pendulum swings. The changed intensity varies the resistance value and was processed by the microcontroller, ATMega328, to obtain a signal period as a function of time and brightness when the pendulum crosses the light. Through the experiment, using calculated average periods, the gravitational acceleration value has been accurately and precisely determined.
Torsional changes in surgery for A-V phenomena.
Sharma, P; Halder, M; Prakash, P
1997-03-01
The role of torsion in the aetiopathogenesis of A-V phenomena has not been sufficiently emphasized. The success of vertical displacement of horizontal recti in correction of A or V has not been attributed to torsional changes. To evaluate this aspect, 21 cases of A or V phenomena were subjected to monocular recession-resection procedure with vertical shifting. Preoperative and postoperative torsional changes were evaluated on synoptophore (subjective torsion), and confirmed by fundus photography (objective torsion). Intorsion with A phenomenon was seen preoperatively in 5 of 8 cases which increased after surgery and was seen postoperatively in the other 3 cases also. Extorsion was observed in 5 of 13 cases pre operatively in 'V' phenomenon, but the changes in extorsion after surgery were less dramatic than those in intorsion. The oblique overactions were reduced in cases where they were present. Correction of A-V phenomena by torsion induced by vertical shifting of horizontal recti muscles is proposed, highlighting the role of torsion in A-V phenomena.
Torsional changes in surgery for A-V phenomena
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Sharma Pradeep
1997-01-01
Full Text Available The role of torsion in the aetiopathogenesis of A-V phenomena has not been sufficiently emphasized. The success of vertical displacement of horizontal recti in correction of A or V has not been attributed to torsional changes. To evaluate this aspect, 21 cases of A or V phenomena were subjected to monocular recession-resection procedure with vertical shifting. Preoperative and postoperative torsional changes were evaluated on synoptophore (subjective torsion, and confirmed by fundus photography (objective torsion. Intorsion with A phenomenon was seen preoperatively in 5 of 8 cases which increased after surgery and was seen postoperatively in the other 3 cases also. Extorsion was observed in 5 of 13 cases pre operatively in ′V′ phenomenon, but the changes in extorsion after surgery were less dramatic than those in intorsion. The oblique overactions were reduced in cases where they were present. Correction of A-V phenomena by torsion induced by vertical shifting of horizontal recti muscles is proposed, highlighting the role of torsion in A-V phenomena.
Dynamic Bending and Torsion Stiffness Derivation from Modal Curvatures and Torsion Rates
MAECK, J.; DE ROECK, G.
1999-08-01
In order to maintain the reliability of civil engineering structures, considerable effort is currently spent on developing a non-destructive vibration testing method for monitoring the structural integrity of constructions. The technique must be able to observe damage, secondly to localize the damage; and finally to give an idea of the severity of the damage. Within the framework of relating changes of measured modal parameters to changes in the integrity of the structure, it is important to be able to determine the dynamic stiffness in each section of the structure from measured modal characteristics.A damaged structure results in a dynamic stiffness reduction of the cracked sections. The dynamic stiffnesses provide directly an indication of the extension of the cracked zones in the structure. The dynamic stiffness reduction can also be associated with a degree of cracking in a particular zone.In an experimental programme, a concrete beam of 6 m length is subjected to an increasing static load to produce cracks. After each static perload, the beam is tested dynamically in a free-free set-up. The change in modal parameters is then related to damage in the beam.The technique that will be presented in the paper to predict the damage location and intensity is a direct stiffness derivation from measured modal displacement derivatives. Using the bending modes, the dynamic bending stiffness can be derived from modal curvatures. Using the torsional modes, the dynamic torsion stiffness can be derived from modal torsion rates.
Torsion based universal MEMS logic device
Ilyas, Saad
2015-10-28
In this work we demonstrate torsion based complementary MEMS logic device, which is capable, of performing INVERTER, AND, NAND, NOR, and OR gates using one physical structure within an operating range of 0-10 volts. It can also perform XOR and XNOR with one access inverter using the same structure with different electrical interconnects. The paper presents modeling, fabrication and experimental calculations of various performance features of the device including lifetime, power consumption and resonance frequency. The fabricated device is 535 μm by 150 μm with a gap of 1.92 μm and a resonant frequency of 6.51 kHz. The device is capable of performing the switching operation with a frequency of 1 kHz.
Combined bending-torsion fatigue reliability. III
Kececioglu, D.; Chester, L. B.; Nolf, C. F., Jr.
1975-01-01
Results generated by three, unique fatigue reliability research machines which can apply reversed bending loads combined with steady torque are presented. AISI 4340 steel, grooved specimens with a stress concentration factor of 1.42 and 2.34, and Rockwell C hardness of 35/40 were subjected to various combinations of these loads and cycled to failure. The generated cycles-to-failure and stress-to-failure data are statistically analyzed to develop distributional S-N and Goodman diagrams. Various failure theories are investigated to determine which one represents the data best. The effects of the groove, and of the various combined bending-torsion loads, on the S-N and Goodman diagrams are determined. Two design applications are presented which illustrate the direct useability and value of the distributional failure governing strength and cycles-to-failure data in designing for specified levels of reliability and in predicting the reliability of given designs.
Plant-based torsional actuator with memory
Plaza, Nayomi; Zelinka, Samuel L.; Stone, Don S.; Jakes, Joseph E.
2013-07-01
A bundle of a few loblolly pine (Pinus taeda) cells are moisture-activated torsional actuators that twist multiple revolutions per cm length in direct proportion to moisture content. The bundles generate 10 N m kg-1 specific torque during both twisting and untwisting, which is higher than an electric motor. Additionally, the bundles exhibit a moisture-activated, shape memory twist effect. Over 70% of the twist in a wetted bundle can be locked-in by drying under constraint and then released by rewetting the bundle. Our results indicate that hemicelluloses dominate the shape fixity mechanism and lignin is primarily responsible for remembering the bundle’s original form. The bundles demonstrate proof of a high specific torque actuator with large angles of rotation and shape memory twist capabilities that can be used in microactuators, sensors, and energy harvesters.
The Inverted Pendulum Benchmark in Nonlinear Control Theory: A Survey
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Olfa Boubaker
2013-05-01
Full Text Available Abstract For at least fifty years, the inverted pendulum has been the most popular benchmark, among others, in nonlinear control theory. The fundamental focus of this work is to enhance the wealth of this robotic benchmark and provide an overall picture of historical and current trend developments in nonlinear control theory, based on its simple structure and its rich nonlinear model. In this review, we will try to explain the high popularity of such a robotic benchmark, which is frequently used to realize experimental models, validate the efficiency of emerging control techniques and verify their implementation. We also attempt to provide details on how many standard techniques in control theory fail when tested on such a benchmark. More than 100 references in the open literature, dating back to 1960, are compiled to provide a survey of emerging ideas and challenging problems in nonlinear control theory accomplished and verified using this robotic system. Possible future trends that we can envision based on the review of this area are also presented.
Torsional malalignment, how much significant in the trochanteric fractures?
Kim, Tae Young; Lee, Yong Beom; Chang, Jun Dong; Lee, Sang Soo; Yoo, Jae Hyun; Chung, Kook Jin; Hwang, Ji Hyo
2015-11-01
The rotational alignment is definitely important in the long bones such as tibias and femurs. We also predict the importance of rotational alignment in the trochanteric fractures. So we measured torsional malalignment in trochanteric fracture and anlaysed their risk factors and their clinical significance. A total of 109 inpatients who had undergone internal fixation following trochanteric fracture and a postoperative pelvic CT scan between 2008 and 2013, with at least one year follow-up, were selected. Factors that affect torsional malalignment, such as age, gender, fracture stability, injured area, operative time, time of surgery after admission, and ASA status, were investigated. Factors that affect the patients' clinical results in malrotation, including ambulation time after surgery, postoperative complication rates, pain assessment of VAS one year postoperatively and Koval score, were also investigated. Of the 109 subjects, torsional malalignment was observed in 28 (25.7%) subjects with a mean torsional malalignment angle of 20.7° (range: -31.2° to 27.1°). Torsional malalignment risk factors were fracture stability (p=0.021) and operative time (p=0.043). In terms of the time to ambulation after surgery, the postoperative complication rates, and the VAS and Koval scores at one year postoperatively, no statistically significant difference was observed between the torsional malalignment patients and the non-deformity patients. In this study, 25.7% of the patients who had undergone internal fixation following trochanteric fracture experienced torsional malalignment. Major factors of the torsional malalignment were an unstable fracture and the consequent delay in the operative time. But the torsional malalignment was deemed to have no effect on clinical results. Copyright © 2015 Elsevier Ltd. All rights reserved.
Ultrafine grained Cu processed by compression with oscillatory torsion
K. Rodak
2007-01-01
Purpose: The aim of this work is a study of Cu microstructure after severe plastic deformation process by usingcompression with oscillatory torsion test.Design/methodology/approach: Cu samples were deformed at torsion frequency (f) changed from 0 Hz(compression) to 1.8 Hz under a constant torsion angle (α) ≈8° and compression speed (v)=0.1mm/s. Structuralinvestigations were conducted by using light microscopy (LM) and transmission electron microscopy (TEM).Findings: The structural analysis ma...
Mathematical modelling of the electrostatic pendulum in school and undergraduate education
International Nuclear Information System (INIS)
Forjan, Matej; Marhl, Marko; Grubelnik, Vladimir
2014-01-01
The electrostatic pendulum, also known as the electrostatic ping-pong, is an exciting experiment in school as well as in undergraduate education. We can easily demonstrate how the frequency of the electrostatic pendulum depends on the voltage across the capacitor. In this paper, we develop a simple mathematical model describing the dynamics of this experiment. In a step-wise manner, we introduce the external forces influencing the dynamics of the electrostatic pendulum. First, we take into account the electric force only. Then, we add air resistance and the non-elasticity of ball collisions with the capacitor plates. The model predictions show that the non-elastic collisions have greater effect on the pendulum dynamics than air resistance; in particular, this is true for higher frequencies of the pendulum. For lower frequencies, however, gravity is of crucial importance. The mathematical model is implemented in a graphic-oriented computer program, which gives the possibility of using this theoretical analysis also at the secondary school level. (paper)
Robust Takagi-Sugeno Fuzzy Dynamic Regulator for Trajectory Tracking of a Pendulum-Cart System
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Miguel A. Llama
2015-01-01
Full Text Available Starting from a nonlinear model for a pendulum-cart system, on which viscous friction is considered, a Takagi-Sugeno (T-S fuzzy augmented model (TSFAM as well as a TSFAM with uncertainty (TSFAMwU is proposed. Since the design of a T-S fuzzy controller is based on the T-S fuzzy model of the nonlinear system, then, to address the trajectory tracking problem of the pendulum-cart system, three T-S fuzzy controllers are proposed via parallel distributed compensation: (1 a T-S fuzzy servo controller (TSFSC designed from the TSFAM; (2 a robust TSFSC (RTSFSC designed from the TSFAMwU; and (3 a robust T-S fuzzy dynamic regulator (RTSFDR designed from the RTSFSC with the addition of a T-S fuzzy observer, which estimates cart and pendulum velocities. Both TSFAM and TSFAMwU are comprised of two fuzzy rules and designed via local approximation in fuzzy partition spaces technique. Feedback gains for the three fuzzy controllers are obtained via linear matrix inequalities approach. A swing-up controller is developed to swing the pendulum up from its pendant position to its upright position. Real-time experiments validate the effectiveness of the proposed schemes, keeping the pendulum in its upright position while the cart follows a reference signal, standing out the RTSFDR.
Foucault pendulum with eddy-current damping of the elliptical motion
Mastner, G.; Vokurka, V.; Maschek, M.; Vogt, E.; Kaufmann, H. P.
1984-10-01
A newly designed Foucault pendulum is described in which the mechanical Charron ring, used throughout in previous designs for damping of the elliptical motion of the pendulum, is replaced by an electromagnetic eddy-current brake, consisting of a permanent magnet attached to the bottom of the bob and a metallic ring. This damping device is very efficient, as it is self-aligning, symmetrical in the damping effect, and never wears out. The permanent magnet is also used, together with a coil assembly and an electronic circuitry, for the dipole-torque drive of the pendulum as well as for accurate stabilization of the amplitude of the swing. A latched time display, controlled by Hall probes activated by the magnet, is used to visualize the Foucault rotation. The pendulum system and its associated electronic circuitry are described in detail. The optimizing of the drive mode is discussed. Measurements of deviations from theoretical value of the Foucault rotation velocity made automatically in a continuous run show a reproducible accuracy of ±1% or better in individual 360° rotations during the summer months. The quality factor of the pendulum as mechanical resonator was measured as a function of the amplitude in the presence of the eddy-current damping ring.
Analysis of the slider force calibration procedure for the British Pendulum Skid Resistance Tester
Hiti, Miha; Ducman, Vilma
2014-02-01
British Pendulum Skid Resistance Testers are being used for the determination of the slip/skid resistance of surfaces by laboratories all around the world in different fields. The instrument itself can give reproducible results; however, the comparison of results obtained by different instruments can show large deviations. This paper presents a comparison of the performance of four pendulum testers, the investigation of requirements in international standards and the analysis of the calibration procedure for the determination of the slider force/deflection characteristics. The slider force/deflection characteristics were measured manually and also automatically with a uniaxial tensile/compression testing machine using different techniques. The results highlight the importance of the slider force/deflection characteristic shape and its influence on the results indicated by the pendulum tester and outline inconsistencies in different international standards describing the same device and its requirements. Presented results show good reproducibility and comparability of the pendulum test results when calibration is performed with the assembled pendulum either manually or automatically, provided the stricter slider force characteristic envelope requirements are taken into consideration. The actual slider force should be stable from 1.5 mm deflection onwards.
3-D Biped Robot Walking along Slope with Dual Length Linear Inverted Pendulum Method (DLLIPM
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Fariz Ali
2013-11-01
Full Text Available A new design method to obtain walking parameters for a three-dimensional (3D biped walking along a slope is proposed in this paper. Most research is focused on the walking directions when climbing up or down a slope only. This paper investigates a strategy to realize biped walking along a slope. In conventional methods, the centre of mass (CoM is moved up or down during walking in this situation. This is because the height of the pendulum is kept at the same length on the left and right legs. Thus, extra effort is required in order to bring the CoM up to higher ground. In the proposed method, a different height of pendulum is applied on the left and right legs, which is called a dual length linear inverted pendulum method (DLLIPM. When a different height of pendulum is applied, it is quite difficult to obtain symmetrical and smooth pendulum motions. Furthermore, synchronization between sagittal and lateral planes is not confirmed. Therefore, DLLIPM with a Newton Raphson algorithm is proposed to solve these problems. The walking pattern for both planes is designed systematically and synchronization between them is ensured. As a result, the maximum force fluctuation is reduced with the proposed method.
IDENTIFICATION METHOD FOR PENDULUM SYSTEM MOMENT OF INERTIA WITH VISCOUS DAMPING
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A. S. Alyshev
2016-09-01
Full Text Available The paper proposes a method for identification of axial moment of inertia of the mechanical system called reaction wheel pendulum with a viscous friction in the bearings of the suspension. The method is based on the reversible symmetric motions. Pendulum system motion includes a free measured motion and reverse symmetrical motion at the same angular interval. The pendulum includes a rod with a low-power DC motor with a flywheel attached to the end of the rod. The angle of rotation and velocity of the rod and the flywheel are measured by encoders. The paper introduces a new method,presents a design formula,a mathematical model of the pendulum system and a robust motor control law for it. The method is based on energy algorithm and control residing in electric motor operational changes by means of a flywheel. The mechanical system moves symmetrically that is provided by nonuniform controlled flywheel rotation. As a result, the influence of dissipative factors on identification results is eliminated. Dynamic modeling is carried out for the pendulum system and proves high accuracy of the method. The research results can be used for identification of complex mechanical systems under the action of resistance, dissipative and other forces.
Nikiforova, Vasilisa
2018-03-01
We consider the model of modified gravity with dynamical torsion. This model was found to have promising stability properties about various backgrounds. The model admits a self-accelerating solution. We have shown previously that if the parameters are adjusted in such a way that the torsion is much greater than the effective cosmological constant, the self-accelerating solution is unstable: there are exponentially growing modes. Here, we study the scalar perturbations in the case when the torsion is of the order of the effective cosmological constant. We find that there are no exponential instabilities.
Evaluation of left ventricular torsion in children with hypertrophic cardiomyopathy.
Prinz, Christian; Faber, Lothar; Horstkotte, Dieter; Körperich, Hermann; Moysich, Axel; Haas, Nikolaus; Kececioglu, Deniz; Thorsten Laser, Kai
2014-04-01
To evaluate the role of torsion in hypertrophic cardiomyopathy in children. A total of 88 children with idiopathic hypertrophic cardiomyopathy (n = 24) and concentric hypertrophy (n = 20) were investigated with speckle-tracking echocardiography and compared with age- and gender-matched healthy controls (n = 44). In hypertrophic cardiomyopathy, we found increased torsion (2.8 ± 1.6 versus 1.9 ± 1.0°/cm [controls], p Hypertrophic cardiomyopathy patients demonstrated a negative correlation between left ventricular muscle mass and torsion (r = -0.7, p hypertrophic cardiomyopathy is characterised by predominantly enhanced systolic basal clockwise rotation. Diastolic untwisting is delayed in both groups. Torsion may be an interesting marker to guide patients with hypertrophic cardiomyopathy.
Isolated adnexal torsion in a 20-week spontaneous twin pregnancy
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Ilker Kahramanoglu
2016-01-01
Discussion: Adnexal torsion as a cause of acute abdomen may be kept in mind in pregnants, even if there is no predisposing factor. Laparoscopy may be performed safely in 2nd trimester for acute abdomen.
Outcomes of Surgery for Posterior Polar Cataract Using Torsional Ultrasound
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Selçuk Sızmaz
2013-10-01
Full Text Available Purpose: The aim of this study is to report outcomes of surgery for posterior polar cataract using torsional ultrasound. Material and Method: Medical records of 26 eyes of 21 consecutive patients with posterior polar cataract who had cataract surgery using the torsional phacoemulsification were evaluated retrospectively. The surgical procedure used, phacoemulsification parameters, intraoperative complications, and postoperative visual outcome were recorded. Results: Of the 26 eyes, 24 (92.3% had small to medium posterior polar opacity. Two eyes had large opacity. All surgeries were performed using the torsional handpiece. Posterior capsule rupture occurred in 4 (15.3% eyes. The mean visual acuity improved significantly after surgery (p<0.001. The postoperative visual acuity was worse than 20/20 in 5 eyes. The cause of the low acuity was amblyopia. Discussion: Successful surgical results and good visual outcome can be achieved with phacoemulsification using the torsional handpiece. (Turk J Ophthalmol 2013; 43: 345-7
Ovarian sparing surgery in cases of giant torsioned ovarian masses
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Yesim Bayoglu Tekin
2015-12-01
Full Text Available Ovarian torsion is a rare gynecological emergency. ovarian torsion is often seen in reproductive ages and salphingooopherectomy is performed for the treatment. However, surgically excision of one of the ovaries early in life causes severe damage to the future fertility. Many case series that were published recently, has been shown low complication rate of ovarian sparing surgery at ovarian torsion and have been preserved from the organ loss. In this study we presented 3 cases at young ages with giant torsioned adnexal masses managed by ovarian sparing surgery at laparotomy and revised the literature in the light of these cases. [J Contemp Med 2015; 5(4.000: 253-256
Damping of Torsional Beam Vibrations by Control of Warping Displacement
DEFF Research Database (Denmark)
Høgsberg, Jan Becker; Hoffmeyer, David; Ejlersen, Christian
2016-01-01
Supplemental damping of torsional beam vibrations is considered by viscous bimoments acting on the axial warping displacement at the beam supports. The concept is illustrated by solving the governing eigenvalue problem for various support configurations with the applied bimoments represented...
Torsion of a wandering spleen | Carapinha | South African Journal of ...
African Journals Online (AJOL)
Abstract. Torsion of a wandering spleen is a rare and difficult diagnosis in the paediatric population, with death a possible outcome. In this paper we present our experience of a single case and discuss the embryology and management thereof.
Amplitude-temperature analysis of hard rubber by torsional vibration
Czech Academy of Sciences Publication Activity Database
Šulc, Petr; Pešek, Luděk; Bula, Vítězslav; Cibulka, Jan; Košina, Jan
2016-01-01
Roč. 821, č. 2016 (2016), s. 295-302 ISSN 1660-9336 Institutional support: RVO:61388998 Keywords : hard rubber * torsion vibration * finite deformation * parameter identification Subject RIV: BI - Acoustics
Primary torsion of vermiform appendix mimicking acute appendicitis.
Marsdin, Emma L; Griffiths, Carl
2011-10-28
Acute appendicitis is a common condition, 8% of the developed world have an appendicectomy in their lifetime. However, torsion of the appendix is a rare disorder first described in 1918 presenting in a manner undistinguishable from acute appendicitis. The authors describe a case of a 48-year-old man who presented with a short history consistent with acute appendicitis. At open appendicectomy, was found to have an acute clockwise torsion of the vermiform appendix at a point 0.5 cm from its base. Histological examination of the specimen was consistent with torsion of the appendix but no underlying cause for the torsion was identified. The postoperative recovery was uneventful; the patient received intravenous antibiotics for a further 48 h and was discharged home without any complications.
Standardized education and parental awareness are lacking for testicular torsion.
Friedman, Ariella A; Ahmed, Haris; Gitlin, Jordan S; Palmer, Lane S
2016-06-01
Testicular torsion leads to orchiectomy in 30-50% of cases, which may cause psychological upset and parental guilt over a potentially avertable outcome. Presentation delay is an important modifiable cause of orchiectomy; yet, families are not routinely educated about torsion or its urgency. The present study assessed parental knowledge regarding acute scrotal pain. An anonymous survey was distributed to parents in Urology and ENT offices, asking about their children's gender and scrotal pain history, urgency of response to a child's acute scrotal pain, and familiarity with testicular torsion. Surveys of 479 urology and 59 ENT parents were analyzed. The results between the two were not statistically different. Among the urology parents, 34% had heard of testicular twisting/torsion, most commonly through friends, relatives or knowing someone with torsion (35%); only 17% were informed by pediatricians (Summary Figure). Parents presenting for a child's scrotal pain were significantly more likely to have heard of torsion (69%) than those presenting for other reasons (30%, OR 5.24, P parents of boys had spoken with their children about torsion. Roughly three quarters of them would seek emergent medical attention - by day (75%) or night (82%) - for acute scrotal pain. However, urgency was no more likely among those who knew about torsion. This was the first study to assess parental knowledge of the emergent nature of acute scrotal pain in a non-urgent setting, and most closely approximating their level of knowledge at the time of pain onset. It also assessed parents' hypothetical responses to the scenario, which was markedly different than documented presentation times, highlighting a potential area for improvement in presentation times. Potential limitations included lack of respondent demographic data, potential sampling bias of a population with greater healthcare knowledge or involvement, and assessment of parents only. Parental knowledge of testicular torsion was
Anthropometric study of angle of femoral torsion in Maharashtrian population
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Anil Kumar Dwivedi
2016-01-01
Full Text Available Introduction: Angle of femoral torsion is a normal torsion or twist present in femur that plays an important role in stability and function of the hip joint. The angle of femoral torsion can be defined as the angle formed by femoral condyle′s plane (bicondylar plane and a plane passing through center of neck and femoral head. Abnormal angle of femoral torsion has been implicated in the etiology of hip osteoarthrosis and developmental dysplasia of hip joint. Materials and Methods: This study was carried out on unpaired 280, adult human femora devoid of any gross pathology, 139 male (65 right and 74 left, and 141 female (71 right and 70 left from bone banks of three medical colleges of Maharashtra. The gender of each specimen was determined by the established practice. Femora were evaluated by Kingsley Olmsted method, and data were tabulated and statistically analyzed. Results: The average angle of femoral torsion 13.39° and 11.23° on the right and left side respectively in male, 16.21° and 13.23° on the right and left side, respectively, in female. Statistical analysis using Student′s "t"-test revealed significant difference (P < 0.05, greater angle of femoral torsion in female and on the right side. Conclusion: Knowledge of angle of femoral torsion is becoming significant nowadays with an increase in demand for total hip replacement, as the angle of femoral torsion is crucial to attain a normal activity of the replaced joint.
Torsion of the greater omentum: A rare preoperative diagnosis
International Nuclear Information System (INIS)
Tandon, Ankit Anil; Lim, Kian Soon
2010-01-01
Torsion of the greater omentum is a rare acute abdominal condition that is seldom diagnosed preoperatively. We report the characteristic computed tomography (CT) scan findings and the clinical implications of this unusual diagnosis in a 41-year-old man, who also had longstanding right inguinal hernia. Awareness of omental torsion as a differential diagnosis in the acute abdomen setting is necessary for correct patient management
High rank elliptic curves with torsion ℤ/4ℤ.
Khoshnam, Foad; Moody, Dustin
2016-01-01
Working over the field ℚ( t ), Kihara constructed an elliptic curve with torsion group ℤ/4ℤ and five independent rational points, showing the rank is at least five. Following his approach, we give a new infinite family of elliptic curves with torsion group ℤ/4ℤ and rank at least five. This matches the current record for such curves. In addition, we give specific examples of these curves with high ranks 10 and 11.
Model of Structural Fragmentation Induced by High Pressure Torsion
Czech Academy of Sciences Publication Activity Database
Kratochvíl, J.; Kružík, Martin; Sedláček, R.
2010-01-01
Roč. 25, č. 1 (2010), s. 88-98 ISSN 1606-5131 Institutional research plan: CEZ:AV0Z10750506 Keywords : High-pressure torsion * intergranular glide * homogeneous deformation mode Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.649, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/kruzik-model of structural fragmentation induced by high pressure torsion.pdf
Torsional Moment Measurement on Bucket Wheel Shaft of Giant Machine
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Jiří FRIES
2011-06-01
Full Text Available Bucket wheel loading at the present time (torsional moment on wheel shaft, peripheral cutting force is determined from electromotor incoming power or reaction force measured on gearbox hinge. Both methods together are weighted by steel construction absorption of driving units and by inertial forces of motor rotating parts. In the article is described direct method of the torsional moment measurement, which eliminates mentioned unfavourable impacts except absorption of steel construction of bucket wheel itself.
The variation of torsion with vergence and elevation.
Porrill, J; Ivins, J P; Frisby, J P
1999-11-01
Two recently developed kinematic models of human eye movements predict systematic departures from Listing's law which are associated with changes in vergence. This vergence-dependent torsion t is proportional to elevation e and vergence v, that is t = kev/2. The proposed value for k is either 1 (Van Rijn, L. J., & Van den Berg, A. V. (1993). Vision Research, 33, 691-708) or 1/2 (Minken, A. W. H., Gielen, C. C. A. M., & Van Gisbergen, J. A. M. (1995). Vision Research, 35, 93-102). One implication of both models is that an eye with a constant fixation direction should exhibit systematic torsional variation during movements of the other eye. This paper therefore examines the torsion produced by moving a fixation target inwards and outwards along the line-of-sight of the right eye at five different viewing elevations (0, +/- 15 and +/- 30 degrees). In a monocular analysis, each eye generally showed intorsion during convergence at positive elevation angles, whereas extorsion occurred at negative elevations; the opposite was true during divergence. However, the torsion response was visibly different between the five subjects, and depended on the direction of target motion. In a binocular analysis, cycloversion (mean of left and right eye torsion) varied dramatically both between subjects and between convergence and divergence; however, cyclovergence (torsional difference) was much less variable. Least-squares methods were used to estimate the constant k from monocular torsion, yielding values between 0.2 and 1.0; however, corresponding estimates based on cyclovergence were all close to 1/2. These findings support suggestions that a binocular control system couples the three-dimensional movements of the eyes, and that an existing model of monocular torsion should be generalised to the binocular case.
Johannessen, Kim
2010-01-01
An analytic approximation of the solution to the differential equation describing the oscillations of a simple pendulum at large angles and with initial velocity is discussed. In the derivation, a sinusoidal approximation has been applied, and an analytic formula for the large-angle period of the simple pendulum is obtained, which also includes…
Grober, S.; Vetter, M.; Eckert, B.; Jodl, H.-J.
2007-01-01
We suggest that different string pendulums are positioned at different locations on Earth and measure at each place the gravitational acceleration (accuracy [delta]g is approximately equal to 0.01 m s[superscript -2]). Each pendulum can be remotely controlled via the internet by a computer located somewhere on Earth. The theoretical part describes…
Jalba, C. K.; Diekmann, R.; Epple, S.
2017-01-01
A pendulum impact tester is a technical device which is used to perform plasticity characterizations of metallic materials. Results are calculated based on fracture behavior under pendulum impact loadings according to DIN 50115, DIN 51222/EN 10045. The material is held at the two ends and gets struck in the middle. A mechanical Problem occurs when testing materials with a very high impact toughness. These specimen often do not break when hit by the pendulum. To return the pendulum to its initial position, the operator presses a service button. After a delay of approximately 2 seconds a clutch is activated which connects the arm of the pendulum with an electric motor to return it back upright in start position. At the moment of clutch activation, the pendulum can still swing or bounce with any speed in any direction at any different position. Due to the lack of synchronization between pendulum speed and constant engine speed, the clutch suffers heavy wear of friction. This disadvantage results in considerable service and repair costs for the customer. As a solution to this problem this article presents a customized technical device to significantly increase the lifetime of the clutch. It was accomplished by a precisely controlled activation of the clutch at a point of time when pendulum and motor are at synchronized speed and direction using incremental encoders.
Energy Technology Data Exchange (ETDEWEB)
Hohenberg, Guenter [IVD Prof. Hohenberg GmbH, Graz (Austria); Beidl, Christian [Technische Univ. Darmstadt (Germany). VKM; Hoefler, Dieter [tectos gmbh, Graz (Austria)
2013-08-01
Plug-in hybrid drives will be, in the foreseeable future, the dominant variant for the electrification of vehicles, with the trend clearly pointing to combustion engines with a low number of cylinders and low engine operating speeds. However, the considerable torsional vibration and its impact on the drive train as well as the engine mount pose a problem. The conventional mechanical solutions with dual mass flywheels and pendulum support etc. have clearly reached their limit when it comes to improving the noise vibration harshness (NVH) behavior. Operating the drive engine with low speed values which are relevant for the fuel consumption is therefore only possible to a limited extent. This paper introduces a technique as a solution to the problem, where the excitation frequency can be doubled with the existing E-motor by generating additional torque pulses. This will achieve the excitation of the drive train and the engine mount as would be the case with a combustion engine with twice the number of cylinders. This technique, referred to as directE strategy, is particularly interesting for 2 und 3-cylinder engines. By combining the individual components into a highly integrated directE hybrid module a simple combination of existing combustion engines and gearboxes can be implemented. This paper describes the technique in more detail, which is followed by a discussion of its advantages, disadvantages and the first practical results. (orig.)
A Complex Overview of Modeling and Control of the Rotary Single Inverted Pendulum System
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Slavka Jadlovska
2013-01-01
Full Text Available The purpose of this paper is to present an in-depth survey of the rotary single inverted pendulum system from a control engineer's point of view. The scope of the survey includes modeling and open-loop analysis of the system as well as design and verification of balancing and swing up controllers which ensure successful stabilization of the pendulum in the unstable upright equilibrium. All relevant tasks and simulation experiments are conducted using the appropriate function blocks, GUI applications and demonstration schemes from a Simulink block library developed by the authors of the paper. The library is called Inverted Pendula Modeling and Control (IPMaC and offers comprehensive program support for modeling, simulation and control of classical (linear and rotary inverted pendulum systems.
A pendulum test as a tool to evaluate viscous friction parameters in the equine fetlock joint.
Noble, Prisca; Lumay, Geoffroy; Coninx, Marc; Collin, Bernard; Magnée, Adrien; Lecomte-Beckers, Jacqueline; Denoix, Jean M; Serteyn, Didier
2011-05-01
An equine fetlock joint pendulum test was studied and the influence of post mortem time and intra-articular lipid solvent on the viscous frictional response examined. Fresh equine digits (group 1, n=6 controls; group 2, n=6 lipid solvent) were mounted on a pendulum tribometer. Assuming that pendular joint damping could be modelled by a harmonic oscillator fluid damping (HOFD), damping time (τ), viscous damping coefficient (c) and friction coefficient (μ) were monitored for 5h under experimental conditions (400N; 20°C). In all experiments, pendular joint damping was found to follow an exponential decay function (R(2)=0.99714), which confirmed that joint damping was fluid. The evolution of τ, c and μ was found to be significantly (Plubricating ability was compromised. This equine pendulum test could be used to test the efficacy of various bio-lubricant treatments. Copyright © 2010 Elsevier Ltd. All rights reserved.
Stabilization of an inverted pendulum system via an SIRM neuro-fuzzy controller
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Kulworawanichpong, T.
2005-01-01
Full Text Available This article presents a new neuro-fuzzy controller to stabilize an inverted pendulum system. The proposed controller consists of the Single Input Rule Modules (SIRMs, the artificial neural network (ANN and the dynamic importance degrees (DIDs. It simultaneously controls both the angle of the pendulum and the position of the cart. The learning of the ANN results in the DIDs. The proposed controller has a simple structure that can decrease the number of fuzzy rules. The simulation results show that the proposed neurofuzzy controller has an ability to stabilize a wide range of the inverted pendulum system within a short periodof time. Moreover, the comparisons of the simulation results between the proposed neuro-fuzzy controller and the SIRMs fuzzy controller are revealed in this article.
Some aspects of the electromagnetic-impulse pendulum and Biot-Savart-Lorentz force
International Nuclear Information System (INIS)
Moyssides, P.G.; Hatzikonstantinou, P.
1988-01-01
The purpose of this paper is to cast light on various serious mistakes which have been involved during the analysis of two experiments, related to the correctness of the Biot-Savart-Lorentz force law. At first in the MIT experiment, carried out by Graneau et al., they claim that the calculated momentum, imparted to an electrodynamic-impulse pendulum, using the BSL force law, is 43% larger than the experimentally measured momentum of the pi-frame pendulum. It has been found that discrepancy, using their own data, is due to the use of a wrong value for the time constant parameter introduced in the current formula. In addition Pappas, like Graneau, although states that all the available energy is dissipated to Joule heating, considers that all the pendulum momentum is imparted to field momentum yielding an enormous amount of field-radiated energy, which is also completely wrong
Optimal control of inverted pendulum system using PID controller, LQR and MPC
Varghese, Elisa Sara; Vincent, Anju K.; Bagyaveereswaran, V.
2017-11-01
Inverted pendulum is a highly nonlinear system. Here we propose an optimal control technique for the control of an inverted Pendulum - cart system. The system is modeled, linearized and controlled. Here, the control objective is to control the system such that when the cart reaches a desired position the inverted pendulum stabilizes in the upright position. Initially PID controller is used to control the system. Later, Linear Quadratic Regulator (LQR) a well-known optimal control technique which makes use of the states of the dynamical system and control input to frame the optimal control decision is used. Various combinations of both PID and LQR controllers are implemented. To validate the robustness of the controller, the system is simulated with and without disturbance. Finally the system is also controlled using Model Predictive controller (MPC). MPC has well predictive ability to calculate future events and implement necessary control actions. The performance of the system is compared and analyzed.
Measuring the fill height of sealed cans with a compound pendulum
Energy Technology Data Exchange (ETDEWEB)
Rinard, P.M.
1995-06-01
A compound pendulum has been designed, fabricated, tested, and used to determine the fill height of material in sealed cans. The specific cans that stimulated this work are partially filled with uranium and plutonium oxide. Fill height affects nondestructive assays using fission neutrons, but corrections for various fill heights can be made once the height is known. Heights vary with use as the powder compacts or loosens, so it is necessary to determine the height at the time of the neutron measurement. The pendulum is small and readily portable so it can be taken to the location of the neutron measurement. Tests with open cans filled with sand to various known heights had accuracies generally within 3%. Factors that can affect the accuracy are examined and discussed. Experience in using the pendulum on sealed cans is related.
Dynamics and swing control of double-pendulum bridge cranes with distributed-mass beams
Huang, Jie; Liang, Zan; Zang, Qiang
2015-03-01
Motion-induced oscillations of crane payloads seriously degrade their effectiveness and safety. Significant progress has been achieved with reducing payload oscillations on a single-pendulum crane with a point-mass payload attached to the end of the cable. However, large payloads and the actual configuration of the hoisting mechanism may transform the crane to a double-pendulum system with a distributed-mass payload. The manipulation task can be more challenging because of the complicated dynamics. The dynamics of bridge cranes transporting distributed-mass beams are derived. A command-smoothing scheme is presented to suppress the complex payload oscillations. Simulations of a large range of motions are used to analyze the dynamic behavior of the cranes and the robustness of the method. Experimental results obtained from a small-scale double-pendulum bridge crane transporting a distributed-mass beam validate the simulated dynamic behavior and the effectiveness of the method.
ESTIMATING TORSION OF DIGITAL CURVES USING 3D IMAGE ANALYSIS
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Christoph Blankenburg
2016-04-01
Full Text Available Curvature and torsion of three-dimensional curves are important quantities in fields like material science or biomedical engineering. Torsion has an exact definition in the continuous domain. However, in the discrete case most of the existing torsion evaluation methods lead to inaccurate values, especially for low resolution data. In this contribution we use the discrete points of space curves to determine the Fourier series coefficients which allow for representing the underlying continuous curve with Cesàro’s mean. This representation of the curve suits for the estimation of curvature and torsion values with their classical continuous definition. In comparison with the literature, one major advantage of this approach is that no a priori knowledge about the shape of the cyclic curve parts approximating the discrete curves is required. Synthetic data, i.e. curves with known curvature and torsion, are used to quantify the inherent algorithm accuracy for torsion and curvature estimation. The algorithm is also tested on tomographic data of fiber structures and open foams, where discrete curves are extracted from the pore spaces.
Bicavitary effusion secondary to liver lobe torsion in a dog
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Khan Z
2016-04-01
Full Text Available Zaheda Khan,1 Kathryn Gates,2 Stephen A Simpson,31Emergency and Critical Care, Animal Specialty and Emergency Center, Los Angeles, CA, 2Emergency and Critical Care, Advanced Critical Care, Emergency and Specialty Services, Culver City, CA 3Emergency and Critical Care, Southern California Veterinary Specialty Hospital, Irvine, CA, USA Abstract: We described the diagnosis and successful treatment of pleural and peritoneal effusion secondary to liver lobe torsion in a dog. A 12-year-old female spayed Borzoi dog was referred for heart failure. Emergency room thoracic and abdominal ultrasound showed a large volume of pleural effusion with mild peritoneal effusion and an abdominal mass. Pleural fluid analysis classified the effusion as exudative. A complete ultrasound revealed mild peritoneal effusion and decreased blood flow to the right liver lobe. Other causes of bicavitary effusion were ruled out based on blood work, ultrasound, echocardiogram, and computed tomography. The patient was taken to surgery and diagnosed with caudate liver lobe torsion and had a liver lobectomy. At the 2-week postoperative recheck, the patient was doing well and there was complete resolution of the pleural effusion. Liver lobe torsion is a rare occurrence in dogs and can be difficult to diagnose. Clinical signs are nonspecific for liver lobe torsion and patients may present in respiratory distress with significant pleural fluid accumulation. When assessing patients with pleural and peritoneal effusion, liver lobe torsion should be considered as a differential diagnosis.Keywords: pleural effusion, peritoneal effusion, hepatic torsion
Directory of Open Access Journals (Sweden)
Faszynka Sebastian
2016-03-01
Full Text Available The paper presents an analysis of the state of stress and crack tip opening displacement (strain in specimens with rectangular cross-section subjected to torsion and combined bending with torsion. The specimens were made of the EN AW-2017A aluminium alloy. The specimens had an external unilateral notch, which was 2 mm deep and its radius was 22.5 mm. The tests were performed at constant moment amplitude MT = MBT = 15.84 N·m and under stress ratio R = −1. The exemplary results of numerical computations being obtained by using the FRANC3D software were shown in the form of stress and crack tip opening displacement (CTOD maps. The paper presents the differences of fatigue cracks growth under torsion and bending with torsion being derived by using the FRANC3D software.
Directory of Open Access Journals (Sweden)
Murat Kemal
2011-12-01
Full Text Available Background and Design: High blood sugar level, insulin resistance and dyslipidemia are accepted to be indicators of impaired carbohydrate metabolism. The potential role of these markers as well as the serum levels of insulin growth factor (IGF-1 and insulin growth factor binding protein (IGFBP-3 in the pathogenesis of molluscum pendulum were investigated in this study. Materials and methods: Forty-five molluscum pendulum patients and 45 age-, sex- and body mass index-matched healthy individuals as controls were enrolled in the study. Evaluation included dermatological examination, measurement of insulin resistance using HOMA-IR method, lipid profile, fasting blood glucose, postprandial blood glucose, fasting insulin, postprandial insulin, serum IGF-1 and IGFBP-3 levels. Results: Postprandial blood glucose, fasting insulin, postprandial insulin and Homeostazis Model Assesment (HOMA-IR levels of molluscum pendulum patients were statistically higher than those of controls (p=0.037, p=0.027, p=0.03, p=0.021 respectively, whereas serum IGF-1 and IGFBP-3 levels were significantly lower than those of controls (p=0.008, p=0.001. There was no difference in fasting glucose and lipid profile between the two groups. Three patients (6.7% had DM and one patient (13.3% had impaired glucose tolerance. Only one participant from the control group (2,2% had impaired glucose tolerance. The number of molluscum pendulum lesions correlated with fasting glucose, postprandial glucose, fasting insulin, postprandial insulin, HOMA-IR, total cholesterol and triglyceride levels. Conclusion: Molluscum pendulum patients should have blood glucose and insulin resistance measurements done and be followed up for DM. Patients with multiple lesions need to be evaluated for lipid problems. We suggest that serum IGF-1 and IGFBP-3 levels have no role in the pathogenesis of molluscum pendulum. (Turkderm 2011; 45: 188-92
Simón-Carballido, Luis; Bao, Junwei Lucas; Alves, Tiago Vinicius; Meana-Pañeda, Rubén; Truhlar, Donald G; Fernández-Ramos, Antonio
2017-08-08
In this work we present the extended two-dimensional torsion (E2DT) method and use it to analyze the performance of several methods that incorporate torsional anharmonicity more approximately for calculating rotational-vibrational partition functions. Twenty molecules having two hindered rotors were studied for temperatures between 100 and 2500 K. These molecules present several kinds of situations; they include molecules with nearly separable rotors, molecules in which the reduced moments of inertia change substantially with the internal rotation, and molecules presenting compound rotation. Partition functions obtained by the rigid-rotor harmonic oscillator approximation, a method involving global separability of torsions and the multistructural methods without explicit potential coupling [MS-T(U)] and with explicit potential coupling [MS-T(C)] of torsions, are compared to those obtained with a quantized version - called the extended two-dimensional torsion (E2DT) method - of the extended hindered rotor approximation of Vansteenkiste et al. ( Vansteenkiste et al. J. Chem. Phys. 2006 , 124 , 044314 ). In the E2DT method, quantum effects due to the torsional modes were incorporated by the two-dimensional nonseparable method, which is a method that is based on the solution of the torsional Schrödinger equation and that includes full coupling in both the kinetic and potential energy. By comparing other methods to the E2DT method and to experimental thermochemical data, this study concludes that the harmonic approximation yields very poor results at high temperatures; the global separation of torsions from the rest of the degrees of freedom is not justified even when an accurate method to treat the torsions is employed; it is confirmed that methods based on less complete potential energy coupling of torsions, such as MS-T(U), are not accurate when dealing with rotors with different barrier heights, and more complete inclusion of torsional coupling to the method in MS
The Bravais pendulum: the distinct charm of an almost forgotten experiment
Energy Technology Data Exchange (ETDEWEB)
Babovic, V M; Mekic, S [Department of Mathematics, Physics and Informatics, State University of Novi Pazar, Vuka Karadzica bb, 36300 Novi Pazar (Serbia)
2011-07-15
In the year 1851 in Paris, the apparent change of the plane of oscillation of a linear pendulum was observed by Leon Foucault. In the same year, at the same place, the unequal duration of the oscillations of a right- and left-handed conical pendulum was observed by Bravais. Today, the Foucault pendula are common at universities, the Bravais pendula not at all. We have revisited and experimentally tested Bravais's method and found it worthy of revitalization in student labs.
A Control of Biped Robot which Applies Inverted Pendulum Mode with Virtual Supporting Point
辻, 俊明; 大西, 公平; TSUJI, Toshiaki; OHNISHI, Kouhei
2002-01-01
We applied the inverted pendulum mode to the control of a biped robot in order to plan a trajectory in real time. Though the inverted pendulum mode is useful to plan a trajectory, the stability margin of a biped robot is very narrow because of its structural limit. Virtual supporting point (VSP), a new indicator of biped robot control, is suggested with a view to broaden the stability margin of biped robot. Walking parameters could be adjusted by setting VSP without changing other parameters....
Self-excited electrostatic pendulum showing electrohydrodynamic-force-induced oscillation
Stephan, Karl D.; Hernandez Guerrero, José M.
2017-12-01
The electrohydrodynamic (EHD) effect ("ion wind") associated with corona discharges in air has been extensively investigated and modeled. We present a simple experiment that shows how both the magnitude and direction of EHD forces can change in such a way as to impart energy continuously to an oscillating electrostatic pendulum. The amplitude of oscillations of an electrostatic pendulum subject to EHD forces can grow approximately exponentially over a period of minutes, and we describe a qualitative theory to account for this effect, along with implications of these experiments for theories of ball lightning.
Chaotic behaviour of an electrical analogue to the mechanical double pendulum
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M. P. Hanias
2008-02-01
Full Text Available In this paper the analogy between a mechanical double pendulum and an oscillating electrical system is presented. Instead of using analytic equations, we used the MultiSim circuit simulation environment in order to reproduce and interpret the response of the electrical oscillator. The electrical double pendulum presents a chaotic regime which is studied quantita-tively by means of state space reconstruction. For this purpose the optimal delay time is calculated and the minimum em-bedding dimension is found with the method of False Nearest Neighbors.
Magnetic resonance imaging findings in adnexial torsion
Energy Technology Data Exchange (ETDEWEB)
Trindade, Ronald Meira Castro; Quadros, Marianne Siquara de [Hospital Albert Einstein, Sao Paulo, SP (Brazil). Instituto de Ensino e Pesquisa], e-mail: rtrindade@einstein.br; Baroni, Ronaldo Hueb; Rosemberg, Michelle; Racy, Marcelo de Castro Jorge; Tachibana, Adriano [Hospital Albert Einstein, Sao Paulo, SP (Brazil); Funari, Marcelo Buarque de Gusmao [Hospital Albert Einstein, Sao Paulo, SP (Brazil). Imaging Service
2010-01-15
Adnexial torsion is an unusual event, but a major cause of abdominal pain in women. It is often associated with ovarian tumor or cyst, but can occur in normal ovaries, especially in children. The twisting of adnexial structures may involve the ovary or tube, but frequently affects both. In most cases, it is unilateral, with slight predilection for the right size. In imaging findings, increased ovarian volume and adnexial masses are observed, with reduced or absent vascularisation. In cases of undiagnosed or untreated complete twist, hemorrhagic necrosis may occur leading to complications; in that, peritonitis is the most frequent. Early diagnosis helps preventing irreversible damage with conservative treatment, thereby saving the ovary. Limitations in performing physical examination, possible inconclusive results in ultrasound and exposure to radiation in computed tomography makes magnetic resonance imaging a valuable tool in emergency assessment of gynecological diseases. The objective of this study was to report two confirmed cases of adnexial twist, emphasizing the contribution of magnetic resonance imaging in the diagnosis of this condition. (author)
The effect of torsional muscle dysfunction and surgery on eye position under general anesthesia.
McCall, L C; Isenberg, S J; Apt, L
1993-01-01
Under general anesthesia, normal eyes exhibit 2.0 degrees to 2.5 degrees of extorsion. To investigate the effect of torsional muscle dysfunction and surgery on eye position under general anesthesia, we measured the torsional change before and after torsional muscle surgery in 26 eyes of 18 patients with clinical torsional muscle dysfunction. Under general anesthesia, compared with normals, eyes with preoperative intorter overaction or extorter underaction demonstrated a significant intorsional change (P extorsion while intorter strengthening procedures and extorter weakening procedures produced measurable intorsion. Superior oblique tenotomy produced a greater net torsional change than inferior oblique weakening surgery (P < .01). Under general anesthesia, eyes with preoperative torsional muscle dysfunction exhibit torsion in the direction consistent with the dysfunction. After surgery on the torsional muscles, a measurable torsional effect can be demonstrated while the patient is still under general anesthesia.
Verreault, René
2017-08-01
In an attempt to explain the tendency of Foucault pendula to develop elliptical orbits, Kamerlingh Onnes derived equations of motion that suggest the use of great circles on a spherical surface as a graphical illustration for an anisotropic bi-dimensional harmonic oscillator, although he did not himself exploit the idea any further. The concept of anisosphere is introduced in this work as a new means of interpreting pendulum motion. It can be generalized to the case of any two-dimensional (2-D) oscillating system, linear or nonlinear, including the case where coupling between the 2 degrees of freedom is present. Earlier pendulum experiments in the literature are revisited and reanalyzed as a test for the anisosphere approach. While that graphical method can be applied to strongly nonlinear cases with great simplicity, this part I is illustrated through a revisit of Kamerlingh Onnes' dissertation, where a high performance pendulum skillfully emulates a 2-D harmonic oscillator. Anisotropy due to damping is also described. A novel experiment strategy based on the anisosphere approach is proposed. Finally, recent original results with a long pendulum using an electronic recording alidade are presented. A gain in precision over traditional methods by 2-3 orders of magnitude is achieved.
Czech Academy of Sciences Publication Activity Database
Kalenda, Pavel; Neumann, L.; Šebela, S.
2013-01-01
Roč. 42, č. 1 (2013), s. 143-154 ISSN 0583-6050 Institutional support: RVO:67985891 Keywords : tilt * pendulum * deformations * earthquakes Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.710, year: 2013 http://ojs.zrc-sazu.si/carsologica/article/view/635
Chaotic Dynamics of the Partially Follower-Loaded Elastic Double Pendulum
DEFF Research Database (Denmark)
Thomsen, Jon Juel
1995-01-01
The non-linear dynamics of the elastically restrained double pendulum, with non-conservative follower-type loading and linear damping, is re-examined with specific reference to the occurrence of chaotic motion. A local non-linear perturbation analysis is performed, showing that in three distinct...
Auto-parametric semi-trivial and post-critical response of a spherical pendulum damper
Czech Academy of Sciences Publication Activity Database
Náprstek, Jiří; Fischer, Cyril
2009-01-01
Roč. 87, 19-20 (2009), s. 1204-1215 ISSN 0045-7949 R&D Projects: GA ČR(CZ) GA103/06/0099 Institutional research plan: CEZ:AV0Z20710524 Keywords : non-linear vibration * spherical pendulum * auto-parametric systems Subject RIV: JM - Building Engineering Impact factor: 1.440, year: 2009
Directory of Open Access Journals (Sweden)
Michal Marszal
2014-01-01
Full Text Available This paper investigates dynamics of double pendulum subjected to vertical parametric kinematic excitation. It includes detailed bifurcation diagrams in two-parameter space (excitation’s frequency and amplitude for both oscillations and rotations in the domain of periodic solutions.
Orion Multi-Purpose Crew Vehicle Solving and Mitigating the Two Main Cluster Pendulum Problem
Ali, Yasmin; Sommer, Bruce; Troung, Tuan; Anderson, Brian; Madsen, Christopher
2017-01-01
The Orion Multi-purpose Crew Vehicle (MPCV) Orion spacecraft will return humans from beyond earth's orbit, including Mars and will be required to land 20,000 pounds of mass safely in the ocean. The parachute system nominally lands under 3 main parachutes, but the system is designed to be fault tolerant and land under 2 main parachutes. During several of the parachute development tests, it was observed that a pendulum, or swinging, motion could develop while the Crew Module (CM) was descending under two parachutes. This pendulum effect had not been previously predicted by modeling. Landing impact analysis showed that the landing loads would double in some places across the spacecraft. The CM structural design limits would be exceeded upon landing if this pendulum motion were to occur. The Orion descent and landing team was faced with potentially millions of dollars in structural modifications and a severe mass increase. A multidisciplinary team was formed to determine root cause, model the pendulum motion, study alternate canopy planforms and assess alternate operational vehicle controls & operations providing mitigation options resulting in a reliability level deemed safe for human spaceflight. The problem and solution is a balance of risk to a known solution versus a chance to improve the landing performance for the next human-rated spacecraft.
Decoupling the structure from the ground motion during earthquakes by employing friction pendulums
Gillich, G. R.; Iancu, V.; Gillich, N.; Korka, Z. I.; Chioncel, C. P.; Hatiegan, C.
2018-01-01
Avoiding dynamic loads on structures during earthquakes is an actual issue since seismic actions can harm or destroy the built environment. Several attempts to prevent this are possible, the essence being to decouple the structure from the ground motion during earthquakes and preventing in this way large deflections and high accelerations. A common approach is the use of friction pendulums, with cylindrical or spherical surfaces but not limited to that, inserted between the ground and the structure, respectively between the pillar and the superstructure. This type of bearings permits small pendulum motion and in this way, earthquake-induced displacements that occur in the bearings are not integrally transmitted to the structure. The consequence is that the structure is subject to greatly reduced lateral loads and shaking movements. In the experiments, conducted to prove the efficiency of the friction pendulums, we made use of an own designed and manufactured shaking table. Two types of sliding surfaces are analyzed, one polynomial of second order (i.e. circular) and one of a superior order. For both pendulum types, analytical models were developed. The results have shown that the structure is really decoupled from the ground motion and has a similar behaviour as that described by the analytic model.
The analitical modeling of the motion process of the inverted pendulum system
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Obukhov Pavel
2017-01-01
Full Text Available In the article the conceptual description of the nonlinear mathematical model of the inverted pendulum is presented. The Lagrange’s equations of the second kind are applying to build of the model, the generalized coordinate are selected and the system of the differential equations of the fourth odder is formed.
A Concise History of School-Based Smoking Prevention Research: A Pendulum Effect Case Study
Sussman, Steve; Black, David S.; Rohrbach, Louise A.
2010-01-01
School-based cigarette smoking prevention was initiated shortly after the first Surgeon General's Report in 1964. This article highlights a sequence of events by which school-based tobacco use prevention research developed as a science, and illustrates a pendulum effect, with confidence in tobacco use prevention increasing and decreasing at…
Mode competition in a system of two parametrically driven pendulums with nonlinear coupling
Banning, E.J.; Banning, E.J.; van der Weele, J.P.; Ross, J.C.; Kettenis, M.M.
1997-01-01
This paper is part three in a series on the dynamics of two coupled, parametrically driven pendulums. In the previous parts Banning and van der Weele (1995) and Banning et al. (1997) studied the case of linear coupling; the present paper deals with the changes brought on by the inclusion of a
Evaluation of the Autoparametric Pendulum Vibration Absorber for a Duffing System
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Benjamın Vazquez-Gonzalez
2008-01-01
Full Text Available In this work we study the frequency and dynamic response of a damped Duffing system attached to a parametrically excited pendulum vibration absorber. The multiple scales method is applied to get the autoparametric resonance conditions and the results are compared with a similar application of a pendulum absorber for a linear primary system. The approximate frequency analysis reveals that the nonlinear dynamics of the externally excited system are suppressed by the pendulum absorber and, under this condition, the primary Duffing system yields a time response almost equivalent to that obtained for a linear primary system, although the absorber frequency response is drastically modified and affected by the cubic stiffness, thus modifying the jumps defined by the fixed points. In the absorber frequency response can be appreciated a good absorption capability for certain ranges of nonlinear stiffness and the internal coupling is maintained by the existing damping between the pendulum and the primary system. Moreover, the stability of the coupled system is also affected by some extra fixed points introduced by the cubic stiffness, which is illustrated with several amplitude-force responses. Some numerical simulations of the approximate frequency responses and dynamic behavior are performed to show the steady-state and transient responses.
Global Study of the Simple Pendulum by the Homotopy Analysis Method
Bel, A.; Reartes, W.; Torresi, A.
2012-01-01
Techniques are developed to find all periodic solutions in the simple pendulum by means of the homotopy analysis method (HAM). This involves the solution of the equations of motion in two different coordinate representations. Expressions are obtained for the cycles and periods of oscillations with a high degree of accuracy in the whole range of…
Extending the permissible control loop latency for the controlled inverted pendulum
Sieber, J.; Krauskopf, B.
2005-01-01
A pendulum can be stabilized in its upright position by proportional-plus-derivative (PD) feedback control only if the latency in the control loop is smaller than a certain critical delay. This critical delay is determined by the presence of a fully symmetric triple-zero eigenvalue singularity, a
[Torsion of wandering spleen in a teenager: about a case].
Dème, Hamidou; Akpo, Léra Géraud; Fall, Seynabou; Badji, Nfally; Ka, Ibrahima; Guèye, Mohamadou Lamine; Touré, Mouhamed Hamine; Niang, El Hadj
2016-01-01
Wandering or migrating spleen is a rare anomaly which is usually described in children. Complications, which include pedicle torsion, are common and can be life-threatening. We report the case of a 17 year-old patient with a long past medical history of epigastric pain suffering from wandering spleen with chronic torsion of the pedicle. The clinical picture was marked by spontaneously painful epigastric mass, evolved over the past 48 hours. Abdominal ultrasound objectified heterogeneous hypertrophied ectopic spleen in epigastric position and a subcapsular hematoma. Doppler showed a torsion of splenic pedicle which was untwisted 2 turns and a small blood stream on the splenic artery. Abdominal CT scan with contrast injection showed a lack of parenchymal enhancement of large epigastric ectopic spleen and a subcapsular hematoma. The diagnosis of wandering spleen with chronic torsion of the pedicle complicated by necrosis and subcapsular hematoma was confirmed. The patient underwent splenectomy. The postoperative course was uneventful. We here discuss the contribution of ultrasound and CT scan in the diagnosis of wandering spleen with chronic torsion of the pedicle.
Whirling sign : an imaging finding indicating ovarian torsion
International Nuclear Information System (INIS)
Cha, Jang Gyu; Kim, Young Hwa; Kim, Hyun Jung; Chang, Yu Jin; Kim, Young Tong; Cho, Won Soo; Bae, Won Kyung; Kim, Il Young
1997-01-01
To present a diagnostic sign on MRI and US in patients with ovarian torsion. We present characteristic imaging findings in eight patients with surgically-proven ovarian torsion. MRI was performed in four patients, CT in six and US in all patients;the procedures including eight transabdominal US (TAS) and three transvaginal US (TVS). In each study, imaging findings were analyzed for the appearance of twisted pedicle and the presence of a 'whirling sign'. The pedicle which indicates ovarian torsion was detected on MRI in all 4 patients, on TAS in 4/7, on TVS in 3/3, and on CT in 4/6. A specific 'whirling sign' was detected on MRI in 2/4 patients, on TAS in 2/4, and on TVS in all three. On CT a 'whirling sign' was not detected. The 'whirling sign' on both MRI and US is a characteristic finding of ovarian torsion;in a patient with adnexal mass and complaining of lower abdominal pain, the presence of this sign is very useful for the diagnosis of ovarian torsion
Prune belly syndrome, splenic torsion, and malrotation: a case report.
Tran, Sifrance; Grossman, Eric; Barsness, Katherine A
2013-02-01
An 18 year old male with a history of prune belly syndrome (PBS) presented with acute abdominal pain and palpable left upper quadrant mass. Computed tomography (CT) of the abdomen revealed a medialized spleen with a "whirl sign" in the splenic vessels, consistent with splenic torsion. Coincidentally, the small bowel was also noted to be on the right side of the abdomen, while the colon was located on the left, indicative of malrotation. Emergent diagnostic laparoscopy confirmed splenic torsion and intestinal malrotation. Successful laparoscopic reduction of the splenic torsion was achieved, however, conversion to an open procedure by a vertical midline incision was necessary owing to the patient's unique anatomy. Open splenopexy with a mesh sling and Ladd's procedure were subsequently performed. Malrotation and wandering spleen are known, rare associated anomalies in PBS; however, both have not been reported concurrently in a patient with PBS in the literature. In patients with PBS, acute abdominal pain, and an abdominal mass, high clinical suspicion for gastrointestinal malformations and prompt attention can result in spleen preservation and appropriate malrotation management. We present a case of a teenager who presented with a history of PBS, acute abdominal pain, and a palpable abdominal mass. The patient was found to have splenic torsion and intestinal malrotation. The clinical findings, diagnostic imaging, and surgical treatment options of splenic torsion are reviewed. Copyright © 2013 Elsevier Inc. All rights reserved.
Torsion of abdominal appendages presenting with acute abdominal pain
International Nuclear Information System (INIS)
Al-Jaberi, Tareq M.; Gharabeih, Kamal I.; Yaghan, Rami J.
2000-01-01
Diseases of abnormal appendages are rare causes of abdominal pain in all age groups. Nine patients with torsion and infraction of abdominal appendages were retrospectively reviewed. Four patients had torsion and infarction of the appendices epiploicae, four patients had torsion and infarction of the falciform ligament. The patient with falciform ligament disease represents the first reported case of primary torsion and infarction of the falciform ligament, and the patient with the transverse colon epiplocia represents the first reported case of vibration-induced appendix epiplocia torsion and infarction. The patient with the falciform ligament disease presented with a tender upper abdominal mass and the remaining patients were operated upon with the preoperative diagnosis of acute appendicitis. The presence of normal appendix with free serosanguinous fluid in the peritoneal cavity should raise the possibility of a disease and calls for further evaluation of the intra-abdominal organs. If the diagnosis is suspected preoperatively, CT scan and ultrasound may lead to a correct diagnosis and possibly conservative management. Laparoscopy is playing an increasing diagnostic and therapeutic role in such situations. (author)
On unified field theories, dynamical torsion and geometrical models: II
International Nuclear Information System (INIS)
Cirilo-Lombardo, D.J.
2011-01-01
We analyze in this letter the same space-time structure as that presented in our previous reference (Part. Nucl, Lett. 2010. V.7, No.5. P.299-307), but relaxing now the condition a priori of the existence of a potential for the torsion. We show through exact cosmological solutions from this model, where the geometry is Euclidean RxO 3 ∼ RxSU(2), the relation between the space-time geometry and the structure of the gauge group. Precisely this relation is directly connected with the relation of the spin and torsion fields. The solution of this model is explicitly compared with our previous ones and we find that: i) the torsion is not identified directly with the Yang-Mills type strength field, ii) there exists a compatibility condition connected with the identification of the gauge group with the geometric structure of the space-time: this fact leads to the identification between derivatives of the scale factor a with the components of the torsion in order to allow the Hosoya-Ogura ansatz (namely, the alignment of the isospin with the frame geometry of the space-time), and iii) of two possible structures of the torsion the 'tratorial' form (the only one studied here) forbid wormhole configurations, leading only to cosmological instanton space-time in eternal expansion
Optical fiber accelerometer based on MEMS torsional micromirror
Zeng, Fanlin; Zhong, Shaolong; Xu, Jing; Wu, Yaming
2008-03-01
A novel structure of optical fiber accelerometer based on MEMS torsional micro-mirror is introduced, including MEMS torsional micro-mirror and optical signal detection. The micro-mirror is a non-symmetric one, which means that the torsional bar supporting the micro-mirror is not located in the axis where the center of the micro-mirror locates. The optical signal detection is composed of PIN diode and dual fiber collimator, which is very sensitive to the coupling angle between the input fiber and output fiber. The detection principle is that acceleration is first transformed into torsional angle of the micro-mirror, then, optical insertion loss of the dual fiber collimator caused by the angle can be received by PIN. So under the flow of acceleration to torsional angle to optical signal attenuation to optical power detection, the acceleration is detected. The theory about sensing and optical signal detect of the device are discussed in this paper. The sensitive structure parameters and performance parameters are calculated by MATLAB. To simulate the static and modal analysis, the finite element analysis, ANSYS, is employed. Based on the above calculation, several optimization methods and the final structure parameters are given. The micro-mirror is completed by using silicon-glass bonding and deep reactive ion etching (DRIE). In the experiment, the acceleration is simulated by electrostatic force and the test results show that the static acceleration detection agrees with the theory analysis very well.
Crack path in aeronautical titanium alloy under ultrasonic torsion loading
Directory of Open Access Journals (Sweden)
A. Nikitin
2016-01-01
Full Text Available This paper discusses features of fatigue crack initiation and growth in aeronautical VT3-1 titanium alloy under pure torsion loading in gigacycle regime. Two materials: extruded and forged VT3-1 titanium alloys were studied. Torsion fatigue tests were performed up to fatigue life of 109 cycles. The results of the torsion tests were compared with previously obtained results under fully reversed axial loading on the same alloys. It has been shown that independently on production process as surface as well subsurface crack initiation may appear under ultrasonic torsion loading despite the maximum stress amplitude located at the specimen surface. In the case of surface crack initiation, a scenario of crack initiation and growth is similar to HCF regime except an additional possibility for internal crack branching. In the case of subsurface crack, the initiation site is located below the specimen surface (about 200 μm and is not clearly related to any material flaw. Internal crack initiation is produced by shear stress in maximum shear plane and early crack growth is in Mode II. Crack branching is limited in the case of internal crack initiation compared to surface one. A typical ‘fish-eye’ crack can be observed at the torsion fracture surface, but mechanism of crack initiation seems not to be the same than under axial fatigue loading.
Autoparallel vs. Geodesic Trajectories in a Model of Torsion Gravity
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Luis Acedo
2015-11-01
Full Text Available We consider a parametrized torsion gravity model for Riemann–Cartan geometry around a rotating axisymmetric massive body. In this model, the source of torsion is given by a circulating vector potential following the celestial parallels around the rotating object. Ours is a variant of the Mao, Tegmark, Guth and Cabi (MTGC model in which the total angular momentum is proposed as a source of torsion. We study the motion of bodies around the rotating object in terms of autoparallel trajectories and determine the leading perturbations of the orbital elements by using standard celestial mechanics techniques. We find that this torsion model implies new gravitational physical consequences in the Solar system and, in particular, secular variations of the semi-major axis of the planetary orbits. Perturbations on the longitude of the ascending node and the perihelion of the planets are already under discussion in the astronomical community, and if confirmed as truly non-zero effects at a statistically significant level, we might be at the dawn of an era of torsion phenomenology in the Solar system.
Autoparallel vs. Geodesic Trajectories in a Model of Torsion Gravity
Acedo, Luis
2015-11-01
We consider a parametrized torsion gravity model for Riemann-Cartan geometry around a rotating axisymmetric massive body. In this model, the source of torsion is given by a circulating vector potential following the celestial parallels around the rotating object. Ours is a variant of the Mao, Tegmark, Guth and Cabi (MTGC model) in which the total angular momentum is proposed as a source of torsion. We study the motion of bodies around the rotating object in terms of autoparallel trajectories and determine the leading perturbations of the orbital elements by using standard celestial mechanics techniques. We find that this torsion model implies new gravitational physical consequences in the Solar system and, in particular, secular variations of the semi-major axis of the planetary orbits. Perturbations on the longitude of the ascending node and the perihelion of the planets are already under discussion in the astronomical community, and if confirmed as truly non-zero effects at a statistically significant level, we might be at the dawn of an era of torsion phenomenology in the Solar system.
Elevated temperature axial and torsional fatigue behavior of Haynes 188
Bonacuse, Peter J.; Kalluri, Sreeramesh
1995-01-01
The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-based superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Code), Manson-Halford, modified multiaxiality factor (proposed in this paper), modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The modified multiaxiality factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.
Residual torsional properties of composite shafts subjected to impact loadings
International Nuclear Information System (INIS)
Sevkat, Ercan; Tumer, Hikmet
2013-01-01
Highlights: • Impact loading reduces the torsional strength of composite shaft. • Impact energy level determines the severity of torsional strength reduction. • Hybrid composite shafts can be manufactured by mixing two types of filament. • Maximum torque capacity of shafts can be estimated using finite element method. - Abstract: This paper presents an experimental and numerical study to investigate residual torsional properties of composite shafts subjected to impact loadings. E-glass/epoxy, carbon/epoxy and E-glass–carbon/epoxy hybrid composite shafts were manufactured by filament winding method. Composite shafts were impacted at 5, 10, 20 and 40 J energy levels. Force–time and energy–time histories of impact tests were recorded. One composite shaft with no impact, and four composite shafts with impact damage, five in total, were tested under torsion. Torque-twisting angle relations for each test were obtained. Reduction at maximum torque and maximum twisting angle induced by impact loadings were calculated. While 5 J impact did not cause significant reduction at maximum torque and maximum twisting angle, remaining impact loadings caused 34–67% reduction at maximum torque, and 30–61% reduction at maximum twisting angle. Reductions increased with increasing energy levels and varied depending on the material of composite shafts. The 3-D finite element (FE) software, Abaqus, incorporated with an elastic orthotropic model, was then used to simulate the torsion tests. Good agreement between experimental and numerical results was achieved
Control of Wind-Induced Vibration of Transmission Tower-Line System by Using a Spring Pendulum
Directory of Open Access Journals (Sweden)
Peng Zhang
2015-01-01
Full Text Available The high-voltage power transmission tower-line system, which is a high flexible structure, is very susceptible to the wind-induced vibrations. This paper proposes the utilization of the internal resonance feature of the spring pendulum to reduce the wind-induced vibration of a transmission tower. The kinetic expression of the spring pendulum system is obtained through Lagrangian equation. The condition of the internal resonance is verified to be λ = 2, in which λ is the ratio of the spring mode frequency over the pendulum mode frequency. A 55 m tower in the Liaoning province is established in SAP2000 to numerically verify the effectiveness of the proposed device. The spring pendulum is modeled using Link element. The wind speed history is generated based on Kaimal spectrum using harmonic superposition method. Results show that, (1 compared with the suspended mass pendulum, the spring pendulum absorbs more energy and reduces the oscillation more effectively and (2 the vibration control performance of the proposed spring pendulum improves as the external wind load increases.
Borisov, A. P.
2018-01-01
The article is devoted to the development of a software and hardware complex for investigating the grinding process on a pendulum deformer. The hardware part of this complex is the Raspberry Pi model 2B platform, to which a contactless angle sensor is connected, which allows to obtain data on the angle of deviation of the pendulum surface, usb-cameras, which allow to obtain grain images before and after grinding, and stepping motors allowing lifting of the pendulum surface and adjust the clearance between the pendulum and the supporting surfaces. The program part of the complex is written in C # and allows receiving data from the sensor and usb-cameras, processing the received data, and also controlling the synchronous-step motors in manual and automatic mode. The conducted studies show that the rational mode is the deviation of the pendulum surface by an angle of 400, and the location of the grain in the central zone of the support surface, regardless of the orientation of the grain in space. Also, due to the non-contact angle sensor, energy consumption for grinding, speed and acceleration of the pendulum surface, as well as vitreousness of grain and the energy consumption are calculated. With the help of photographs obtained from usb cameras, the work of a pendulum deformer based on the Rebinder formula and calculation of the grain area before and after grinding is determined.
Changes in stature following plyometric drop-jump and pendulum exercises.
Fowler, N E; Lees, A; Reilly, T
1997-12-01
The aim of this study was to compare the changes in stature following the performance of plyometric exercises using drop-jumps and a pendulum swing. Eight male participants aged 21.7 +/- 1.8 years with experience of plyometric training gave their informed consent to act as participants. Participants undertook two exercise regimens and a 15-min standing test in a random order. The exercises entailed the performance of 50 drop-jumps from a height of 0.28 m or 50 pendulum rebounds. Participants were instructed to perform maximal jumps or rebounds using a 'bounce' style. Measurements of stature were performed after a 20-min period of standing (pre-exercise), 2-min after exercise (post-exercise) and after a 20-min standing recovery (recovery). Back pain and muscle soreness were assessed using an analogue-visual scale, at each of the above times and also 24 and 36 h after the test. Peak torque during isokinetic knee extension at 1.04 rads-1 was measured immediately before and after the exercise bouts, to assess the degree of muscular fatigue. Ground/wall reaction force data were recorded using a Kistler force platform mounted in the floor for drop-jumps and vertically on the rebound wall for pendulum exercises. Drop-jumps resulted in the greatest (p Drop-jumps resulted in significantly greater peak impact forces (p drop-jumps = 3.2 +/- 0.5 x body weight, pendulum = 2.6 +/- 0.5 x body weight). The two exercise conditions both invoked a small degree of muscle soreness but there were no significant differences between conditions. Both exercise regimens resulted in a non-significant decrease in peak torque indicating a similar degree of muscular fatigue. Based on the lower shrinkage resulted and lower peak forces, it can be concluded that pendulum exercises pose a lower injury potential to the lower back than drop-jumps performed from a height of 28 cm.
Abnormalities of Penile Curvature: Chordee and Penile Torsion
Directory of Open Access Journals (Sweden)
Sylvia Montag
2011-01-01
Full Text Available Congenital chordee and penile torsion are commonly observed in the presence of hypospadias, but can also be seen in boys with the meatus in its orthotopic position. Varying degrees of penile curvature are observed in 4–10% of males in the absence of hypospadias. Penile torsion can be observed at birth or in older boys who were circumcised at birth. Surgical management of congenital curvature without hypospadias can present a challenge to the pediatric urologist. The most widely used surgical techniques include penile degloving and dorsal plication. This paper will review the current theories for the etiology of penile curvature, discuss the spectrum of severity of congenital chordee and penile torsion, and present varying surgical techniques for the correction of penile curvature in the absence of hypospadias.
Increased external tibial torsion in Osgood-Schlatter disease.
Gigante, Antonio; Bevilacqua, Claudia; Bonetti, Massimo G; Greco, Francesco
2003-08-01
We studied the relationship between Osgood-Schlatter disease and torsional abnormalities of the lower limb in 21 boys with this condition and 20 age- and sex-matched controls. 3 groups of knees (20 control knees, 21 symptomatic and 21 asymptomatic or less symptomatic knees) were subjected to clinical, radiographic and CT evaluation. We found no statistically significant differences between patients and controls, as regards femoral anteversion, patellar congruence angle, patellar tilt angle and anterior tibial tuberosity-trochlear groove distance, but the condylomalleolar angle and tibial torsion angle were greater in patients. We found no differences between symptomatic and asymptomatic or less symptomatic knees in any of the parameters. All the symptomatic knees were on the side preferentially involved in jumping and sprinting. This increase in external tibial torsion may play a role as a predisposing mechanical factor in the onset of Osgood-Schlatter disease in male athletes.
Mechanical Design of AM Fabricated Prismatic Rods under Torsion
Directory of Open Access Journals (Sweden)
Manzhirov Alexander V.
2017-01-01
Full Text Available We study the stress-strain state of viscoelastic prismatic rods fabricated or repaired by additive manufacturing technologies under torsion. An adequate description of the processes involved is given by methods of a new scientific field, mechanics of growing solids. Three main stages of the deformation process (before the beginning of growth, in the course of growth, and after the termination of growth are studied. Two versions of statement of two problems are given: (i given the torque, find the stresses, displacements, and torsion; (ii given the torsion, find the stresses, displacements, and torque. Solution methods using techniques of complex analysis are presented. The results can be used in mechanical and instrument engineering.
In vitro transcription of a torsionally constrained template
DEFF Research Database (Denmark)
Bentin, Thomas; Nielsen, Peter E
2002-01-01
RNA polymerase (RNAP) and the DNA template must rotate relative to each other during transcription elongation. In the cell, however, the components of the transcription apparatus may be subject to rotary constraints. For instance, the DNA is divided into topological domains that are delineated...... of torsionally constrained DNA by free RNAP. We asked whether or not a newly synthesized RNA chain would limit transcription elongation. For this purpose we developed a method to immobilize covalently closed circular DNA to streptavidin-coated beads via a peptide nucleic acid (PNA)-biotin conjugate in principle...... mimicking a SAR/MAR attachment. We used this construct as a torsionally constrained template for transcription of the beta-lactamase gene by Escherichia coli RNAP and found that RNA synthesis displays similar characteristics in terms of rate of elongation whether or not the template is torsionally...
Simple currents versus orbifolds with discrete torsion - a complete classification
International Nuclear Information System (INIS)
Kreuzer, M.; Schellekens, A.N.
1993-01-01
We give a complete classification of all simple current modular invariants, extending previous results for (Z p ) k to arbitrary centers. We obtain a simple explicit formula for the most general case. Using orbifold techniques to this end, we find a one-to-one correspondence between simple current invariants and subgroups of the center with discrete torsions. As a by-product, we prove the conjectured monodromy independence of the total number of such invariants. The orbifold approach works in a straightforward way for symmetries of odd order, but some modifications are required to deal with symmetries of even order. With these modifications the orbifold construction with discrete torsion is complete within the class of simple current invariants. Surprisingly, there are cases where discrete torsion is a necessity rather than a possibility. (orig.)
Standing torsional waves in a fully saturated, porous, circular cylinder
Solorza, S; 10.1111/j.1365-246X.2004.02198.x
2004-01-01
For dynamic measurement of the elastic moduli of a porous material saturated with viscous fluid using the resonance-bar technique, one also observes attenuation. In this article we have carried out the solution of the boundary-value problem associated with standing torsional oscillations of a finite, poroelastic, circular cylinder cast in the framework of volume-averaged theory of poroelasticity. Analysing this solution by eigenvalue perturbation approach we are able to develop expressions for torsional resonance and temporal attenuation frequencies in which the dependence upon the material properties are transparent. It shows how the attenuation is controlled by the permeability and the fluid properties, and how the resonance frequency drops over its value for the dry solid-frame due to the drag effect of fluid mass. Based upon this work we have a firm basis to determine solid-frame shear modulus, permeability, and tortuosity factor from torsional oscillation experiments.
Fault diagnosis of planetary gearboxes via torsional vibration signal analysis
Feng, Zhipeng; Zuo, Ming J.
2013-04-01
Torsional vibration signals are theoretically free from the amplitude modulation effect caused by time variant vibration transfer paths due to the rotation of planet carrier and sun gear, and therefore their spectral structure are simpler than transverse vibration signals. Thus, it is potentially easy and effective to diagnose planetary gearbox faults via torsional vibration signal analysis. We give explicit equations to model torsional vibration signals, considering both distributed gear faults (like manufacturing or assembly errors) and local gear faults (like pitting, crack or breakage of one tooth), and derive the characteristics of both the traditional Fourier spectrum and the proposed demodulated spectra of amplitude envelope and instantaneous frequency. These derivations are not only effective to diagnose single gear fault of planetary gearboxes, but can also be generalized to detect and locate multiple gear faults. We validate experimentally the signal models, as well as the Fourier spectral analysis and demodulation analysis methods.
2009-12-01
During earthquake excitations, reinforced concrete bridge columns can be subjected to a combination of axial load, shear force, : flexural moments, and torsional moments. The torsional moment can be much more significant in columns of bridges that ar...
Deep learning methods for protein torsion angle prediction.
Li, Haiou; Hou, Jie; Adhikari, Badri; Lyu, Qiang; Cheng, Jianlin
2017-09-18
Deep learning is one of the most powerful machine learning methods that has achieved the state-of-the-art performance in many domains. Since deep learning was introduced to the field of bioinformatics in 2012, it has achieved success in a number of areas such as protein residue-residue contact prediction, secondary structure prediction, and fold recognition. In this work, we developed deep learning methods to improve the prediction of torsion (dihedral) angles of proteins. We design four different deep learning architectures to predict protein torsion angles. The architectures including deep neural network (DNN) and deep restricted Boltzmann machine (DRBN), deep recurrent neural network (DRNN) and deep recurrent restricted Boltzmann machine (DReRBM) since the protein torsion angle prediction is a sequence related problem. In addition to existing protein features, two new features (predicted residue contact number and the error distribution of torsion angles extracted from sequence fragments) are used as input to each of the four deep learning architectures to predict phi and psi angles of protein backbone. The mean absolute error (MAE) of phi and psi angles predicted by DRNN, DReRBM, DRBM and DNN is about 20-21° and 29-30° on an independent dataset. The MAE of phi angle is comparable to the existing methods, but the MAE of psi angle is 29°, 2° lower than the existing methods. On the latest CASP12 targets, our methods also achieved the performance better than or comparable to a state-of-the art method. Our experiment demonstrates that deep learning is a valuable method for predicting protein torsion angles. The deep recurrent network architecture performs slightly better than deep feed-forward architecture, and the predicted residue contact number and the error distribution of torsion angles extracted from sequence fragments are useful features for improving prediction accuracy.
Primary decomposition of torsion R[X]-modules
Directory of Open Access Journals (Sweden)
William A. Adkins
1994-01-01
Full Text Available This paper is concerned with studying hereditary properties of primary decompositions of torsion R[X]-modules M which are torsion free as R-modules. Specifically, if an R[X]-submodule of M is pure as an R-submodule, then the primary decomposition of M determines a primary decomposition of the submodule. This is a generalization of the classical fact from linear algebra that a diagonalizable linear transformation on a vector space restricts to a diagonalizable linear transformation of any invariant subspace. Additionally, primary decompositions are considered under direct sums and tensor product.
A black hole with torsion in 5D Lovelock gravity
Cvetković, B.; Simić, D.
2018-03-01
We analyze static spherically symmetric solutions of five dimensional (5D) Lovelock gravity in the first order formulation. In the Riemannian sector, when torsion vanishes, the Boulware–Deser black hole represents a unique static spherically symmetric black hole solution for the generic choice of the Lagrangian parameters. We show that a special choice of the Lagrangian parameters, different from the Lovelock Chern–Simons gravity, leads to the existence of a static black hole solution with torsion, the metric of which is asymptotically anti-de Sitter (AdS). We calculate the conserved charges and thermodynamical quantities of this black hole solution.
Massless fermions and Kaluza--Klein theory with torsion
International Nuclear Information System (INIS)
Wu, Y.; Zee, A.
1984-01-01
A pure Kaluza--Klein theory contains no massless fermion in four-dimensional theory. We investigate the effect of introducing torsion on the internal manifold and find that there are massless fermions. The hope is that given an isometry group the representation to which these fermions belong is fixed, in contrast to the situation in Yang--Mills theory. We show that this is indeed the case, but the representations do not appear to be the ones favored by current theoretical prejudice. The cases with parallelizable torsions on a group manifold as the internal manifold are analyzed in detail
Spontaneous compactification and Ricci-flat manifolds with torsion
International Nuclear Information System (INIS)
McInnes, B.
1985-06-01
The Freund-Rubin mechanism is based on the equation Rsub(ik)=lambdagsub(ik) (where lambda>0), which, via Myers' Theorem, implies ''spontaneous'' compactification. The difficulties connected with the cosmological constant in this approach can be resolved if torsion is introduced and lambda set equal to zero, but then compactification ''by hand'' is necessary, since the equation Rsub(ik)=0 can be satisfied both on compact and on non-compact manifolds. In this paper we discuss the global geometry of Ricci-flat manifolds with torsion, and suggest ways of restoring the ''spontaneity'' of the compactification. (author)
[Torsion of the vermiform appendix associated with intussusception].
Baeza-Herrera, Carlos; García-Cabello, Luis Manuel; León-Cruz, Alberto; Martínez-Rivera, María de Lourdes
2006-01-01
Vermiform appendix torsion is a rare condition, with only 25 cases recorded in the international literature. Our patient is the first case associated with intussusception. A 2-month-old female infant suddenly developed severe abdominal pain due to ileoceal intussusception. During surgical exploration, a tight intussusception was reduced. Three days later, a new laparotomy was required and we found torsion and perforation of the vermiform appendix. The patient underwent appendectomy, but there was dehiscence of the appendiceal stump and cecal perforation requiring a new surgical exploration. The patient had an uneventful recovery.
REILLY, RICHARD; WHELAN, ROBERT
2009-01-01
PUBLISHED Familial adult-onset primary torsion dystonia is an autosomal dominant disorder with markedly reduced penetrance. Most adult-onset primary torsion dystonia patients are sporadic cases. Disordered sensory processing is found in adult-onset primary torsion dystonia patients; if also present in their unaffected relatives this abnormality may indicate non-manifesting gene carriage. Temporal discrimination thresholds (TDTs) are abnormal in adult-onset primary torsion dystonia, but the...
Energy Technology Data Exchange (ETDEWEB)
Esparza, J.; Gonzalez, A.; Cordero, J. L. [Hospital Virgen del Camino. Pamplona (Spain)
2000-07-01
To determine the efficacy of ultrasound in boys presenting torsion of a testicular appendage. A series of 30 boys with acute scrotal pain due to torsion of a testicular appendage was studied. Nine patients underwent surgery. The clinical findings and course in the remaining 21 suggested the presence of this abnormality. All of them underwent conventional and color Doppler ultrasound using a 7.5 MHz transducer. In 15 boys, ultrasound images depicted the affected appendage as a mass between the epididymal head and the testicle. In 13 cases, only signs of a inflammatory reaction, with enlargement of the epididymal head and tunicas presenting hyperflow and hydrocele, mimicking acute epididymities. In two cases, the images were normal. There is no definitive, distinguishing ultrasound image corresponding to testicular appendage torsion. Therefore, this diagnostic technique should be accompanied by clinical assessment. (Author) 14 refs.
APPLICATION OF THE METHOD OF DIMENSIONALITY REDUCTION TO CONTACTS UNDER NORMAL AND TORSIONAL LOADING
Directory of Open Access Journals (Sweden)
Emanuel Willert
2015-08-01
In view of all this, the torsional contact problems have been disregarded until now, although it is known that torsion is a major reason of wear and possible failure of system components. Therefore, in the present paper, we extend the MDR to contacts of axisymmetric profiles under superimposed normal and torsional loading.
Szopa, Andrzej; Domagalska-Szopa, Małgorzata; Kidoń, Zenon; Syczewska, Małgorzata
2014-12-16
Development of a reliable and objective test of spasticity is important for assessment and treatment of children with cerebral palsy. The pendulum test has been reported to yield reliable measurements of spasticity and to be sensitive to variations in spasticity in these children. However, the relationship between the pendulum test scores and other objective measures of spasticity has not been studied. The present study aimed to assess the effectiveness of an accelerometer-based pendulum test as a measurement of spasticity in CP, and to explore the correlation between the measurements of this test and the global index of deviation from normal gait in in children with cerebral palsy. We studied thirty-six children with cerebral palsy, including 18 with spastic hemiplegia and 18 with spastic diplegia, and a group of 18 typically-developing children. Knee extensor spasticity was assessed bilaterally using the accelerometer-based pendulum test and three-dimensional gait analysis. The Gillette Gait Index was calculated from the results of the gait analysis. The data from the accelerometer-based pendulum test could be used to distinguish between able-bodied children and children with cerebral palsy. Additionally, two of the measurements, first swing excursion and relaxation index, could be used to differentiate the degree of knee extensor spasticity in the children with cerebral palsy. Only a few moderate correlations were found between the Gillette Gait Index and the pendulum test data. This study demonstrates that the pendulum test can be used to discriminate between typically developing children and children with CP, as well as between various degrees of spasticity, such as spastic hemiplegia and spastic diplegia, in the knee extensor muscle of children with CP. Deviations from normal gait in children with CP were not correlated with the results of the pendulum test.
Axial Torsion of Gangrenous Meckel's Diverticulum Causing Small ...
African Journals Online (AJOL)
dividing the band. Resection and anastomosis of the small bowel including the MD was performed. We hereby report a rare and unusual complication of a MD. Although treatment outcome is generally good, pre-operative diagnosis is often difficult. Key words: Axial torsion, Meckel's diverticulum, small bowel obstruction.
Effect of irregularity on torsional surface waves in an initially ...
Indian Academy of Sciences (India)
The Earth is considered as an initially stressed body with a layered ... Keywords. Torsional wave; anisotropy; initial stress; irregularity; non-homogeneity. J. Earth Syst. Sci., DOI 10.1007/s12040-016-0689-7, 125, No. 4, June 2016, pp. 885–895 ...... wave dispersion in a finitely prestrained hollow sandwich circular cylinder; J.
Torsional vibrations of infinite composite poroelastic cylinders | Shah ...
African Journals Online (AJOL)
The displacements of second and third torsional modes are determined and presented graphically for the ratio of radius of composite poroelastic solid cylinder to the radius of the inner solid cylinder. Results of previous works are shown as special case of the present analysis. By ignoring liquid effects, the results of purely ...
Torsional vibration of thin-walled elastic beams with doubly ...
African Journals Online (AJOL)
In this paper, the problem of analyzing the torsional vibration of thin-walled elastic beams, with open cross-sections that are doubly symmetric and traversed by moving concentrated masses at constant speeds is addressed. The mathematical model adopted accounts for both the gravitational and inertial effects of the ...
The ground state torsion rotation spectrum of CH2DOH
Pearson, John C.; Yu, Shanshan; Drouin, Brian J.
2012-10-01
The ground state torsion rotation spectrum of CH2DOH has been completely characterized through J = 30 and Ka = 10, 9, 9 in the three torsional sub-states of the ground state; e0, e1, and o1, respectively. Additional a-type assignments are presented to Ka = 11 in each of the torsional sub-states. The data has been analyzed with an empirical power series model as well as an empirical internal axis model. Over 8000 transitions have been assigned and fit with near experimental accuracy over the range of 4-1628 GHz. The characterization of the spectrum allows for a complete set of ground state term values enabling a better understanding of the infrared spectrum. Comparison of the torsional contributions of the Hamiltonian with normal methanol provides great insight into the nature of the asymmetric-top asymmetric-frame internal rotation problem. The comparison with normal methanol also provides a relatively straightforward transformation from the well understood C3V internal rotation problem to the completely asymmetric internal rotation problem. The data and analysis provide some practical wisdom on the impacts of breaking the symmetry and the choice of models for addressing the nearly three fold completely asymmetric internal rotation problem.
Influence of rigid boundary on the propagation of torsional surface ...
Indian Academy of Sciences (India)
Influence of rigid boundary on the propagation of torsional surface wave in an inhomogeneous layer. Shishir Gupta. ∗. , Rehena Sultana and Santimoy Kundu. Department of Applied Mathematics, Indian School of Mines, Dhanbad 826 004, India. ∗. Corresponding author. e-mail: shishir ism@yahoo.com. The present work ...
Influence of rigid boundary on the propagation of torsional surface ...
Indian Academy of Sciences (India)
ered media are very important to seismologists in understanding the cause and ... layered media. Bhattacharya (1975) investigated the torsional wave propagation in a two layered circular cylinder with imperfect bond. Vardoulakis. (1984) has shown that ...... Naturalist Society in Zurich 66 181–195. Ozturk A and Akbarov S D ...
Penile Torsion: an Overlooked Anomaly with Distal Hypospadias ...
African Journals Online (AJOL)
The angle of penile rotation was measured on an end-on digital photograph of the penis, using MillenMed DICOM viewer program for image analysis. Two techniques were used to correct penile torsion. In group A (9 patients), we used the technique of degloving and repositioning the penile skin. In group B (10 patients), we ...
Portal venous thrombosis developing after torsion of a wandering ...
African Journals Online (AJOL)
The etiological factors are the congenital absence of the ligaments that hold the spleen in its normal anatomic position, or the relaxation of these ligaments resulting from conditions like trauma and abdominal surgery. We aimed to present a rare case with torsion of wandering spleen that consequently developed thrombosis ...
Penile torsion correction by diagonal corporal plication sutures
Directory of Open Access Journals (Sweden)
Brent W. Snow
2009-02-01
Full Text Available Penile torsion is commonly encountered. It can be caused by skin and dartos adherence or Buck’s fascia attachments. The authors suggest a new surgical approach to solve both problems. If Buck’s fascia involvement is demonstrated by artificial erection then a new diagonal corporal plication suture is described to effectively solve this problem.
In vitro transcription of a torsionally constrained template
DEFF Research Database (Denmark)
Bentin, Thomas; Nielsen, Peter E
2002-01-01
of torsionally constrained DNA by free RNAP. We asked whether or not a newly synthesized RNA chain would limit transcription elongation. For this purpose we developed a method to immobilize covalently closed circular DNA to streptavidin-coated beads via a peptide nucleic acid (PNA)-biotin conjugate in principle...
Ocular torsion before and after 1 hour centrifugation
Groen, E.; Graaf, B. de; Bles, W.; Bos, J.E.
1996-01-01
To assess a possible otolith contribution to effects observed following prolonged expo-sure to hyper gravity, we used video-oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after one hour of centrifugation with a Gx-load of 3G. Static
Ocular torsion before and after 1 hour centrifugation
Groen, Eric; De Graaf, Bernd; Bles, Willem; Bos, Jelte E.
1996-01-01
To assess a possible otolith contribution to effects observed following prolonged exposure to hypergravity, we used video oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after t h of centrifugation with a G(x)-load of 3 G. Static tilt
Investigation of torsional vibrations in thick walled hollow poroelastic ...
Indian Academy of Sciences (India)
Abstract. This paper deals with the study of torsional vibrations of thick walled hollow poroelastic cylinder using Biot's extension theory. Considering the boundaries to be stress free, the frequency equation is obtained in the presence of dissipation which is transcendental and complex valued in nature. In the special case of ...
Timoshenko-Wagner-Kappus Torsion Bending Theory and Wind ...
Indian Academy of Sciences (India)
Timoshenko-Wagner-Kappus Torsion Bending. Theory and Wind Tunnel Balance Design. S P Govinda Raju and K R Y Simha. S P Govinda Raju is a. Professor at the. Aero- space Engineering. Department, Indian. Institute of Science,. Bangalore. His interests are fluid mechanics, aircraft design, testing and analysis.
Testicular torsion: Needless testicular loss can be prevented
African Journals Online (AJOL)
2011-12-06
Dec 6, 2011 ... Background: The risk of losing the testis is an ever present threat in patients with testicular torsion, who delay before presenting to the surgeon. A retrospective study was carried out to audit patients with acute scrotal pain who came to the Trans Ekulu Hospital Enugu, the promptness of offering them surgical ...
Development of Torsional and Linear Piezoelectrically Driven Motors
Duong, Khanh; Newton, David; Garcia, Ephrahim
1996-01-01
The development of rotary and linear inchworm-motors using piezoelectric actuators is presented. The motors' design has the advantage of a macro and micro stepper motor with high load and speed. The torsional design is capable of fast angular positioning with micro level accuracy. Additionally, the rotary motor, as designed, can be used as a clutch/brake mechanism. Constructed prototype motors of both types along with their characteristics are presented. The torsional motor consists of a torsional section that provides angular displacement and torque, and two alternating clamping sections which provide the holding force. The motor relies on the principal piezoelectric coupling coefficient (d33) with no torsional elements, increasing its torque capability. The linear motor consists of a longitudinal vibrator that provides displacement and load, and two alternating clamping sections which provide the holding force. This design eliminates bending moment, tension and shear applied to the actuator elements, increase its load capability and life. Innovative flexure designs have been introduced for both motor types. Critical issues that affect the design and performance of the motors are explored and discussed. Experiments are performed demonstrating the motor prototypes based on the aforementioned design considerations.
The static characteristics of a torsionally flexible metal coupling
Directory of Open Access Journals (Sweden)
Krzysztof FILIPOWICZ
2008-01-01
Full Text Available The paper presents a description of test stands and the methodology ofdetermining the static characteristics of a metal coupling of high torsional flexibility. In addition, the paper presents preliminary tests results which enable to determine the above characteristics.
Triorchidism with Torsion | Kumar | Annals of Medical and Health ...
African Journals Online (AJOL)
Polyorchidism is a rare anomaly; triorchidism is the commonest type and is frequently associated with cryptorchidism, inguinal hernia, and testicular torsion. It is also reported as an increased risk of testicular malignancy. We report a case of 72.year.old man with left supernumerary testes in the left hemiscrotum.
Torsion of bars with regular polygonal sections | Zongo | Global ...
African Journals Online (AJOL)
In this article, the study of the torsion of cylindrical bars using large singular finite elements method leads to the resolution of the system of linear equations using MATLAB software. Particularly, the numerical solution of the problem of beams with regular section shows clearly the precision of the method depending upon the ...
Tumour, Torsion or Trauma? | Nduhiu | Annals of African Surgery
African Journals Online (AJOL)
We present a case of a 22 year old who was managed by various levels of clinicians for a 12 day period prior to testicular exploration which finally revealed testicular torsion. Remarkably, the testis was viable and the finding of a hematoma of the epididymis suggested a history of trauma which was not forthcoming from the ...
Testicular torsion on the Jos Plateau | Ugwu | West African Journal ...
African Journals Online (AJOL)
In order to determine the pattern and the factors that influenced outcome, we retrospectively studied fifty-seven patients with torsion of the testis admitted to the Jos University Teaching hospital between August 1993 and July 2001. The age ranged from 2 to 55 years with a mean of 22.7 years. Majority (79%) of the patients ...
Origin of methyl torsional potential barrier–An overview
Indian Academy of Sciences (India)
This paper presents the evolution of views on methyl internal rotation potential barrier. Various mechanisms proposed for the origin of torsional barrier in ethane have been reviewed. Inadequacy of one dimensional description of internal rotation has been highlighted in small methyl conjugated molecules in the light of its ...
Testicular torsion: Needless testicular loss can be prevented | Njeze ...
African Journals Online (AJOL)
Background: The risk of losing the testis is an ever present threat in patients with testicular torsion, who delay before presenting to the surgeon. A retrospective study was carried out to audit patients with acute scrotal pain who came to the Trans Ekulu Hospital Enugu, the promptness of offering them surgical treatment and ...
Timoshenko–Wagner–Kappus Torsion Bending Theory and Wind ...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 10. Timoshenko–Wagner–Kappus Torsion Bending Theory and Wind Tunnel Balance Design. S P Govinda Raju K R Y Simha. General Article Volume 7 Issue 10 October 2002 pp 54-58 ...
f(R) gravity, torsion and non-metricity
International Nuclear Information System (INIS)
Sotiriou, Thomas P
2009-01-01
For both f(R) theories of gravity with an independent symmetric connection (no torsion), usually referred to as Palatini f(R) gravity theories, and for f(R) theories of gravity with torsion but no non-metricity, called U4 theories, it has been shown that the independent connection can actually be eliminated algebraically, as long as this connection does not couple to matter. Remarkably, the outcome in both cases is the same theory, which is dynamically equivalent with an ω 0 = -3/2 Brans-Dicke theory. It is shown here that even for the most general case of an independent connection with both non-metricity and torsion, one arrives at exactly the same theory as in the more restricted cases. This generalizes the previous results and explains why assuming that either the torsion or the non-metricity vanishing ultimately leads to the same theory. It also demonstrates that f(R) actions cannot support an independent connection which carries dynamical degrees of freedom, irrespective of how general this connection is, at least as long as there is no connection-matter coupling. (fast track communication)
Increased external tibial torsion and osteochondritis dissecans of the knee
Bramer, J. A. M.; Maas, M.; Dallinga, R. J.; te Slaa, R. L.; Vergroesen, D. A.
2004-01-01
In the past, osteochondritis dissecans of the knee was associated with increased tibial exotorsion, established with a clinical measuring method. Now the gold standard for determining tibial torsion is computed tomography. The aim of the current study was to establish whether the abovementioned
Numerical simulation of lateral-torsional buckling of coped girders
Maljaars, J.; Steenbergen, H.M.G.M.; Stark, J.W.B.; Abspoel, R.
2002-01-01
The lateral torsional buckling resistance of girders depends on the support conditions. In floor structures for buildings, coped girders are often used. A numerical model was developed to research the influence of copes on lateral buckling resistance. The model is successfully validated with tests.
Direct excitation of resonant torsional Alfven waves by footpoint motions
Ruderman, M. S.; Berghmans, D.; Goossens, M.; Poedts, S.
1997-01-01
The present paper studies the heating of coronal loops by linear resonant Alfven waves that are excited by the motions of the photospheric footpoints of the magnetic field lines. The analysis is restricted to torsionally polarised footpoint motions in an axially symmetric system so that only
Torsion of an Epiploic Appendix Pretending as Acute Appendicitis
Directory of Open Access Journals (Sweden)
Kamran Ahmad Malik
2010-07-01
Full Text Available Torsion of an epiploic appendix is a rare surgical entity. Its unusual symptomatology, wide variation in physical findings and the absence of helpful laboratory and radiological studies makes it very difficult to diagnose pre-operatively. This is a report of this rare entity found in a patient upon diagnostic laparoscopy performed for suspected acute appendicitis
Absence of torsion for NK_1(R) over associative rings
Basu, Rabeya
2010-01-01
When R is a commutative ring with identity, and if k is a natural number with kR = R, then C. Weibel proved that SK_1(R[X]) has no k-torsion. We reprove his result for any associative ring R with identity in which kR = R.
Spectral Action for Torsion with and without Boundaries
DEFF Research Database (Denmark)
Iochum, B.; Levy, Cyril Olivier; Vassilevich, D.
2012-01-01
We derive a commutative spectral triple and study the spectral action for a rather general geometric setting which includes the (skew-symmetric) torsion and the chiral bag conditions on the boundary. The spectral action splits into bulk and boundary parts. In the bulk, we clarify certain issues...
Torsion of the Spermatic Cord: An Exemplary Early Presentation
African Journals Online (AJOL)
2017-10-26
Oct 26, 2017 ... Case Report. How to cite this article: Oluyemi OY. Torsion of the spermatic cord: an exemplary early presentation. Niger J Clin Pract 2017;XX;000-000. This is an open ... and the new creations are licensed under the identical terms. For reprints contact: ..... Financial Source of Support. None. Conflicts of ...
International Nuclear Information System (INIS)
Groeber, S; Vetter, M; Eckert, B; Jodl, H-J
2007-01-01
We suggest that different string pendulums are positioned at different locations on Earth and measure at each place the gravitational acceleration (accuracy Δg ∼ 0.01 m s -2 ). Each pendulum can be remotely controlled via the internet by a computer located somewhere on Earth. The theoretical part describes the physical origin of this phenomenon g(ψ), that the Earth's effective gravitational acceleration g depends on the angle of latitude ψ. Then, we present all necessary formula to deduce g(ψ) from oscillations of a string pendulum. The technical part explains tips and tricks to realize such an apparatus to measure all necessary values with sufficient accuracy. In addition, we justify the precise dimensions of a physical pendulum such that the formula for a mathematical pendulum is applicable to determine g(ψ) without introducing errors. To conclude, we describe the internet version-the string pendulum as a remotely controlled laboratory. The teaching relevance and educational value will be discussed in detail at the end of this paper including global experimenting, using the internet and communication techniques in teaching and new ways of teaching and learning methods
Nagasaka, Imao; Ishida, Yukio; Koyama, Takayuki; Fujimatsu, Naoki
Currently, some kinds of helicopters use pendulum absorbers in order to reduce vibrations. Present pendulum absorbers are designed based on the antiresonance concept used in the linear theory. However, since the vibration amplitudes of the pendulum are not small, it is considered that the nonlinearity has influence on the vibration characteristics. Therefore, the best suppression cannot be attained by using the linear theory. In a helicopter, periodic forces act on the blades due to the influences of the air thrust. These periodic forces act on the blades with the frequency which is the integer multiple of the rotational speed of the rotor. Our previous study proposed a 2-degree-of-freedom (2DOF) model composed of a rotor blade and a pendulum absorber. The blade was considered as a rigid body and it was excited by giving a sinusoidal deflection at its end. The present paper proposes a 3DOF model that is more similar to the real helicopter, since the freedom of the fuselage is added and the periodic forces are applied to the blade by aerodynamic force. The vibration is analyzed considering the nonlinear characteristics. The resonance curves of rotor blades with pendulum absorbers are obtained analytically and experimentally. It is clarified that the most efficient condition is obtained when the natural frequency of the pendulum is a little bit different from the frequency of the external force. Various unique nonlinear characteristics, such as bifurcations, are also shown.
Quantum torsion with non-zero standard deviation: Non-perturbative approach for cosmology
Energy Technology Data Exchange (ETDEWEB)
Dzhunushaliev, Vladimir, E-mail: v.dzhunushaliev@gmail.com [Dept. Theor. and Nucl. Phys., KazNU, Almaty, 010008 (Kazakhstan); Institute for Basic Research, Eurasian National University, Astana, 010008 (Kazakhstan); Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Folomeev, Vladimir, E-mail: vfolomeev@mail.ru [Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, 265 a, Chui Street, Bishkek, 720071 (Kyrgyzstan); Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Kleihaus, Burkhard, E-mail: b.kleihaus@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Kunz, Jutta, E-mail: jutta.kunz@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany)
2013-02-12
Cosmology with non-perturbative quantum corrections resulting from torsion is considered. It is shown that the evolution of closed, open and flat Universes is changed because of the presence of a non-zero dispersion of quantum torsion. The evolution of a Universe with quantum torsion and with one type of average curvature can be similar to the evolution of a Universe without quantum torsion and with another type of average curvature. For the description of the non-perturbative quantum torsion, a vector field approximation is applied.
Ramachandran, Rahul; Nosonovsky, Michael
2014-07-14
The phenomenon of liquid droplets "levitating" or bouncing off a liquid vibrating surface has attracted attention of scientists due to its possible application in microfluidics and novel nanostructured superhydrophobic materials. Several models have been suggested in the literature, and the effect is usually attributed to non-linear viscosity. Here we suggest a simple model relating the effect to the parametric resonance as described by the Mathieu equation, which explains stabilization of an inverted pendulum with vibration foundation. Small fast vibrations can be substituted by an effective "levitation" force. We present modeling and experimental results for oil droplets and discuss how the mathematical separation of the slow and fast motion provides insights on the relation of vibro-levitation of oil droplets and soft materials with the vibro-stabilization of an inverted pendulum, and the "Indian rope" and "Cornstarch monster" tricks.
Optical pendulum effect in one-dimensional diffraction-thick porous silicon based photonic crystals
Energy Technology Data Exchange (ETDEWEB)
Novikov, V. B., E-mail: vb.novikov@physics.msu.ru; Svyakhovskiy, S. E.; Maydykovskiy, A. I.; Murzina, T. V.; Mantsyzov, B. I. [Department of Physics, M. V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation)
2015-11-21
We present the realization of the multiperiodic optical pendulum effect in 1D porous silicon photonic crystals (PhCs) under dynamical Bragg diffraction in the Laue scheme. The diffraction-thick PhC contained 360 spatial periods with a large variation of the refractive index of adjacent layers of 0.4. The experiments reveal switching of the light leaving the PhC between the two spatial directions, which correspond to Laue diffraction maxima, as the fundamental wavelength or polarization of the incident light is varied. A similar effect can be achieved when the temperature of the sample or the intensity of the additional laser beam illuminating the crystal are changed. We show that in our PhC structures, the spectral period of the pendulum effect is down to 5 nm, while the thermal period is about 10 °C.
Directory of Open Access Journals (Sweden)
H. Vázquez-Leal
2013-01-01
Full Text Available In theoretical mechanics field, solution methods for nonlinear differential equations are very important because many problems are modelled using such equations. In particular, large deflection of a cantilever beam under a terminal follower force and nonlinear pendulum problem can be described by the same nonlinear differential equation. Therefore, in this work, we propose some approximate solutions for both problems using nonlinearities distribution homotopy perturbation method, homotopy perturbation method, and combinations with Laplace-Padé posttreatment. We will show the high accuracy of the proposed cantilever solutions, which are in good agreement with other reported solutions. Finally, for the pendulum case, the proposed approximation was useful to predict, accurately, the period for an angle up to 179.99999999∘ yielding a relative error of 0.01222747.
A Wave Power Device with Pendulum Based on Ocean Monitoring Buoy
Chai, Hui; Guan, Wanchun; Wan, Xiaozheng; Li, Xuanqun; Zhao, Qiang; Liu, Shixuan
2018-01-01
The ocean monitoring buoy usually exploits solar energy for power supply. In order to improve power supply capacity, this paper proposes a wave power device according to the structure and moving character of buoy. The wave power device composes of pendulum mechanism that converts wave energy into mechanical energy and energy storage mechanism where the mechanical energy is transferred quantitatively to generator. The hydrodynamic equation for the motion of buoy system with generator devise is established based on the potential flow theory, and then the characteristics of pendulum motion and energy conversion properties are analysed. The results of this research show that the proposed wave power devise is able to efficiently and periodically convert wave energy into power, and increasing the stiffness of energy storage spring is benefit for enhancing the power supply capacity of the buoy. This study provides a theory reference for the development of technology on wave power generator for ocean monitoring buoy.
Yang, Jing; Zhang, Da-hai; Chen, Ying; Liang, Hui; Tan, Ming; Li, Wei; Ma, Xian-dong
2017-10-01
A novel floating pendulum wave energy converter (WEC) with the ability of tide adaptation is designed and presented in this paper. Aiming to a high efficiency, the buoy's hydrodynamic shape is optimized by enumeration and comparison. Furthermore, in order to keep the buoy's well-designed leading edge always facing the incoming wave straightly, a novel transmission mechanism is then adopted, which is called the tidal adaptation mechanism in this paper. Time domain numerical models of a floating pendulum WEC with or without tide adaptation mechanism are built to compare their performance on various water levels. When comparing these two WECs in terms of their average output based on the linear passive control strategy, the output power of WEC with the tide adaptation mechanism is much steadier with the change of the water level and always larger than that without the tide adaptation mechanism.
Aranda-Escolástico, Ernesto; Guinaldo, María; Gordillo, Francisco; Dormido, Sebastián
2016-11-01
In this paper, periodic event-triggered controllers are proposed for the rotary inverted pendulum. The control strategy is divided in two steps: swing-up and stabilization. In both cases, the system is sampled periodically but the control actions are only computed at certain instances of time (based on events), which are a subset of the sampling times. For the stabilization control, the asymptotic stability is guaranteed applying the Lyapunov-Razumikhin theorem for systems with delays. This result is applicable to general linear systems and not only to the inverted pendulum. For the swing-up control, a trigger function is provided from the derivative of the Lyapunov function for the swing-up control law. Experimental results show a significant improvement with respect to periodic control in the number of control actions. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
Suzuki, Tomoyuki; Tsuji, Toshiaki; Shibuya, Maki; Ohnishi, Kouhei
Motion planning of a biped robot based on ZMP is quite popular in recent years. In this method, ZMP reference trajectory is planned at first so that ZMP stays inside of the support polygon. Then, walking pattern is generated based on the trajectory. Conventional methods based on ZMP reference trajectory did not take the dynamics of bipedal locomotion into account. Therefore, the basis of the motion planning was ambiguous and the biped robot did not get human-like walking. This paper proposes ZMP reference trajectory generation with inverted pendulum model by using VSP (Virtual Supporting Point). With this, smooth ZMP reference trajectory based on the dynamics of the inverted pendulum is generated uniquely according to the desired stride and walking cycle.
Coupled oscillators in identification of nonlinear damping of a real parametric pendulum
Olejnik, Paweł; Awrejcewicz, Jan
2018-01-01
A damped parametric pendulum with friction is identified twice by means of its precise and imprecise mathematical model. A laboratory test stand designed for experimental investigations of nonlinear effects determined by a viscous resistance and the stick-slip phenomenon serves as the model mechanical system. An influence of accurateness of mathematical modeling on the time variability of the nonlinear damping coefficient of the oscillator is proved. A free decay response of a precisely and imprecisely modeled physical pendulum is dependent on two different time-varying coefficients of damping. The coefficients of the analyzed parametric oscillator are identified with the use of a new semi-empirical method based on a coupled oscillators approach, utilizing the fractional order derivative of the discrete measurement series treated as an input to the numerical model. Results of application of the proposed method of identification of the nonlinear coefficients of the damped parametric oscillator have been illustrated and extensively discussed.
Experimental and theoretical analysis of auto-parametric stability of pendulum with viscous dampers
Czech Academy of Sciences Publication Activity Database
Pospíšil, Stanislav; Fischer, Cyril; Náprstek, Jiří
2011-01-01
Roč. 56, č. 4 (2011), s. 359-378 ISSN 0001-7043 R&D Projects: GA AV ČR(CZ) IAA200710805; GA ČR(CZ) IAA200710902; GA ČR(CZ) GA103/09/0094 Institutional research plan: CEZ:AV0Z20710524 Keywords : auto-parametric pendulum * variable damping * semi-trivial stability * limit cycles Subject RIV: JM - Building Engineering
A note on the accuracy of a computable approximation for the period of a pendulum
Directory of Open Access Journals (Sweden)
Eric Oden
2015-06-01
Full Text Available We discuss the accuracy of a previously proposed computable approximation for the period of the simple pendulum. In particular, we apply known inequalities for the Gaussian hypergeometric function to prove that the associated error is a monotonic function of the maximum angular displacement, α. For any given range of α, this provides an analytical verification of a precise bound for the associated error.
Extending The Lossy Spring-Loaded Inverted Pendulum Model with a Slider-Crank Mechanism
Orhon, H. Eftun; Odabas, Caner; Uyanik, Ismail; Morgul, Omer; Saranli, Uluc
2015-01-01
Spring Loaded Inverted Pendulum (SLIP) model has a long history in describing running behavior in animals and humans as well as has been used as a design basis for robots capable of dynamic locomotion. Anchoring the SLIP for lossy physical systems resulted in newer models which are extended versions of original SLIP with viscous damping in the leg. However, such lossy models require an additional mechanism for pumping energy to the system to control the locomotion and to reach a limit-cycle. ...
Dynamic Obstacle Overcoming Capability of Pendulum-driven Ball-Shaped Robots
Ylikorpi, Tomi; Forsman, Pekka; Halme, Aarne
2014-01-01
This paper discusses dynamic step-crossing capability of pendulum-driven ball-shaped robots. We introduce an extended dynamic model that allows modeling of ballrobot rolling, bouncing and slipping. Based on the new model, our simulations predict the maximum over-passable step-height for the robot. The simulation results agree well with the result from a parallel simulation in Adamssoftware as well as with practical experiments. The new dynamic model can be applied for mobility analysis of rob...
The Reaction Wheel Pendulum: An Interactive Virtual Laboratory for Control Education
Directory of Open Access Journals (Sweden)
Arturo García
2010-08-01
Full Text Available This paper describes a virtual laboratory which illustrates a real-world application of fundamental control principles: the Reaction Wheel Pendulum. The goal of the paper is to motivate students to learn in a practical way different fundamental aspects of control processes. The laboratory has been developed using the programming support provided by Easy Java Simulations, an open-source tool for teachers with limited programming skills who want to create Java applications and applets.
Types and stability of quasi-periodic response of a spherical pendulum
Czech Academy of Sciences Publication Activity Database
Náprstek, Jiří; Fischer, Cyril
2013-01-01
Roč. 124, č. 8 (2013), s. 74-87 ISSN 0045-7949 R&D Projects: GA ČR(CZ) GA103/09/0094; GA AV ČR(CZ) IAA200710902 Institutional support: RVO:68378297 Keywords : non-linear vibration * spherical pendulum * auto-parametric systems * quasi-periodic processes * dynamic stability * asymptotic methods Subject RIV: JM - Building Engineering Impact factor: 2.178, year: 2013 http://www.sciencedirect.com/science/article/pii/S0045794912002672
Aerodynamic stability of long span suspension bridges with low torsional natural frequencies
DEFF Research Database (Denmark)
Andersen, Michael Styrk; Johansson, Jens; Brandt, Anders
2016-01-01
Classical flutter of suspended bridge decks can be avoided if the torsional frequencies are lower than the vertical. Wind tunnel tests of single boxes and twin box section models with torsional natural frequencies above and below the vertical frequency has been conducted. Flutter was avoided in all...... tests where the torsional frequency was lower than the vertical. But too low torsional stiffness caused large static displacements of the girder at medium–high wind speeds and steady state oscillations driven by a combination of torsional divergence and stalling behavior at the critical wind seed....... In order to design aerodynamically stable suspension bridges with low torsional natural frequencies it is suggested to increase the mass moment of inertia and provide adequate torsional stiffness by the main cables spacing....
Designing of Proportional Sliding Mode Controller for Linear One Stage Inverted Pendulum
Directory of Open Access Journals (Sweden)
Anirban Banrejee
2011-01-01
Full Text Available The control of Inverted Pendulum (IP is a hugely complex task. A great deal of nonlinearity is present inherently and as well as affected by the surrounding external conditions. The sliding mode controller (SMC is very robust inherently. It is used in this paper to control the IP. This paper examines the designing of sliding mode controller (SMC for a linear inverted pendulum (IP. The paper highlights the important features of the sliding mode and also throws ample lights on the designing guidelines. The paper puts special impetus on the mathematical modeling of the controller. The robustness of the design of SMC with proportional control is amply displayed with the help of simple mathematics. It gives rise to a controller which can control a highly nonlinear system like IP quite efficiently. The performance of the SMC is compared with fuzzy and PID controller. The edge this controller poses is the key aspect of this paper. External disturbances and internal inaccuracies are also introduced to the system to bring out the robustness of the controller to the fore. Background on sliding mode and the pendulum are provided. Simulation results are displayed in a vivid manner and explained suitably.
Directory of Open Access Journals (Sweden)
Monika Koul
2017-01-01
Full Text Available Introduction: The purpose of this prospective study was to analyze the efficiency of pendulum appliance for distalizing maxillary first molar while decreasing the anchorage loss by banding first and second premolar and making them one unit. Materials and Methods: The study group comprised of 20 patients (mean age 13 ± 2 years who had skeletal Class I and Angle's Class II molar relation. Modified pendulum appliance was given to distalize maxillary first molar and to decrease the anchorage loss both first and second premolars were banded as a single unit by soldering a 19-gauge stainless steel wire. Then both skeletal and dental changes were measured on the pretreatment and posttreatment lateral cephalograms. Results: The maxillary molar was distalized, and a Class I molar relation was achieved in 3 ± 2 months. Maxillary first molar distalized by 4.48 mm in the region of dental crown by tipping distally an average of 8.5°. Both the premolars tipped distally significantly. Thus, by this modification, the anchor loss was minimized. Conclusion: It was concluded that the efficiency of pendulum appliance was increased by this modification, as the anchorage was increased, the space loss was minimized.
Application of Firefly Algorithm for Parameter Estimation of Damped Compound Pendulum
Directory of Open Access Journals (Sweden)
Saad Mohd Sazli
2016-01-01
Full Text Available This paper presents an investigation into the parameter estimation of the damped compound pendulum using Firefly algorithm method. In estimating the damped compound pendulum, the system necessarily needs a good model. Therefore, the aim of the work described in this paper is to obtain a dynamic model of the damped compound pendulum. By considering a discrete time form for the system, an autoregressive with exogenous input (ARX model structures was selected. In order to collect input-output data from the experiment, the PRBS signal is used to be input signal to regulate the motor speed. Where, the output signal is taken from position sensor. Firefly algorithm (FA algorithm is used to estimate the model parameters based on model 2nd orders. The model validation was done by comparing the measured output against the predicted output in terms of the closeness of both outputs via mean square error (MSE value. The performance of FA is measured in terms of mean square error (MSE.
International Nuclear Information System (INIS)
Missal, B.; Leher, F.; Schiller, T.; Friedrich, P.; Capriccioli, A.
2014-01-01
Highlights: • Plasma vessel support has to allow vertical adjustment and horizontal passive movement. • Planar sliding tables with PTFE do not fulfill all requirements. • Pendulums can fulfill all requirements. • Geometry and material of spherical bearings had to be optimized in calculations and tests. • Optimized pendulums were manufactured and assembled. - Abstract: The superconducting helical advanced stellarator Wendelstein 7-X (W7-X) is under construction at the Max-Planck-Institut für Plasmaphysik (IPP) in Greifswald, Germany. The three dimensional shape of plasma will be generated by 50 non-planar magnetic coils. The plasma vessel geometry follows exactly this three dimensional shape of plasma. To ensure the superconductivity of coils a cryo vacuum has to be generated. Therefore the coils and their support structure are enclosed within the outer vessel. Plasma vessel, coil structures and outer vessel have to be supported separately. This paper will describe the vertical supports of plasma vessel which have to fulfill two special requirements, vertical adjustability and horizontal mobility. These two tasks will be carried out by plasma vessel supports (PVS) with hydraulic cylinders, special sliding tables during assembly and pendulum supports during operating phase. The paper will give an overview of design, calculation, tests, fabrication, assembly, critical aspects and status of PVS
Energy Technology Data Exchange (ETDEWEB)
Missal, B., E-mail: bernd.missal@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Leher, F.; Schiller, T. [MAN Diesel and Turbo SE, Werftstraße 17, 94469 Deggendorf (Germany); Friedrich, P. [Universität Rostock, FB Maschinenbau und Schiffstechnik, Albert-Einsteins-Straße 2, 18051 Rostock (Germany); Capriccioli, A. [ENEA Frascati, Fusion Technology Unit, Frascati (Italy)
2014-10-15
Highlights: • Plasma vessel support has to allow vertical adjustment and horizontal passive movement. • Planar sliding tables with PTFE do not fulfill all requirements. • Pendulums can fulfill all requirements. • Geometry and material of spherical bearings had to be optimized in calculations and tests. • Optimized pendulums were manufactured and assembled. - Abstract: The superconducting helical advanced stellarator Wendelstein 7-X (W7-X) is under construction at the Max-Planck-Institut für Plasmaphysik (IPP) in Greifswald, Germany. The three dimensional shape of plasma will be generated by 50 non-planar magnetic coils. The plasma vessel geometry follows exactly this three dimensional shape of plasma. To ensure the superconductivity of coils a cryo vacuum has to be generated. Therefore the coils and their support structure are enclosed within the outer vessel. Plasma vessel, coil structures and outer vessel have to be supported separately. This paper will describe the vertical supports of plasma vessel which have to fulfill two special requirements, vertical adjustability and horizontal mobility. These two tasks will be carried out by plasma vessel supports (PVS) with hydraulic cylinders, special sliding tables during assembly and pendulum supports during operating phase. The paper will give an overview of design, calculation, tests, fabrication, assembly, critical aspects and status of PVS.
Approximate expressions for the period of a simple pendulum using a Taylor series expansion
Energy Technology Data Exchange (ETDEWEB)
Belendez, Augusto; Marquez, Andres; Ortuno, Manuel; Gallego, Sergi [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Arribas, Enrique, E-mail: a.belendez@ua.es [Departamento de Fisica Aplicada, Escuela Superior de IngenierIa Informatica, Universidad de Castilla-La Mancha, Avda de Espana, s/n, E-02071 Albacete (Spain)
2011-09-15
An approximate scheme for obtaining the period of a simple pendulum for large-amplitude oscillations is analysed and discussed. When students express the exact frequency or the period of a simple pendulum as a function of the oscillation amplitude, and they are told to expand this function in a Taylor series, they always do so using the oscillation amplitude as the variable, without considering that if they change the variable (in this paper to the new variable m), a different Taylor series expansion may be performed which is in addition more accurate than previously published ones. Students tend to believe that there is one and only one way of performing a Taylor series expansion of a specific function. The approximate analytical formula for the period is obtained by means of a Taylor expansion of the exact frequency taking into account the Kidd-Fogg formula for the period. This approach based on the Taylor expansion of the frequency about a suitable value converges quickly even for large amplitudes. We believe that this method may be very useful for teaching undergraduate courses on classical mechanics and helping students understand nonlinear oscillations of a simple pendulum.
A new paradigm for human stick balancing: a suspended not an inverted pendulum.
Lee, Kwee-Yum; O'Dwyer, Nicholas; Halaki, Mark; Smith, Richard
2012-09-01
We studied 14 skilled subjects balancing a stick (a television antenna, 52 cm, 34 g) on their middle fingertip. Comprehensive three-dimensional analyses revealed that the movement of the finger was 1.75 times that of the stick tip, such that the balanced stick behaved more like a normal noninverted pendulum than the inverted pendulum common to engineering models for stick balancing using motors. The average relation between the torque applied to the stick and its angle of deviation from the vertical was highly linear, consistent with simple harmonic motion. We observed clearly greater rotational movement of the stick in the anteroposterior plane than the mediolateral plane. Despite this magnitude difference, the duration of stick oscillatory cycles was very similar in both planes, again consistent with simple harmonic motion. The control parameter in balancing was the ratio of active torque applied to the stick relative to gravitational torque. It determined both the pivot point and oscillatory cycle period of the pendulum. The pivot point was located at the radius of gyration (about the centre of mass) of the stick from its centre of mass, showing that the subjects attuned to the gravitational dynamics and mass distribution of the stick. Hence, the key to controlling instability here was mastery of the physics of the unstable object. The radius of gyration may--similar to centre of mass--contribute to the kinesthesis of rotating limb segments and control of their gravitational dynamics.
Analysis of Free Pendulum Vibration Absorber Using Flexible Multi-Body Dynamics
Directory of Open Access Journals (Sweden)
Emrah Gumus
2016-01-01
Full Text Available Structures which are commonly used in our infrastructures are becoming lighter with progress in material science. These structures due to their light weight and low stiffness have shown potential problem of wind-induced vibrations, a direct outcome of which is fatigue failure. In particular, if the structure is long and flexible, failure by fatigue will be inevitable if not designed properly. The main objective of this paper is to perform theoretical analysis for a novel free pendulum device as a passive vibration absorber. In this paper, the beam-tip mass-free pendulum structure is treated as a flexible multibody dynamic system and the ANCF formulation is used to demonstrate the coupled nonlinear dynamics of a large deflection of a beam with an appendage consisting of a mass-ball system. It is also aimed at showing the complete energy transfer between two modes occurring when the beam frequency is twice the ball frequency, which is known as autoparametric vibration absorption. Results are discussed and compared with findings of MSC ADAMS. This novel free pendulum device is practical and feasible passive vibration absorber in the mitigation of large amplitude wind-induced vibrations in traffic signal structures.
Angelieri, Fernanda; Almeida, Renato Rodrigues de; Almeida, Marcio Rodrigues de; Fuziy, Acácio
2006-04-01
This prospective clinical study analyzed the distalization of maxillary molars achieved by the pendulum appliance and its effect on the anchorage teeth during and after fixed orthodontic treatment. Lateral cephalograms of 22 adolescents (15 girls, 7 boys) taken pretreatment, after distalization, after leveling and aligning, and after fixed orthodontic treatment were evaluated. The initial mean age was 14.5 years (SD = 1.80). The mean time for distalization of the maxillary molars was 5.85 months (SD = 1.82), and the total treatment time was 3.61 years (SD = 1.83). The pendulum appliance moved the maxillary molars distally, but with significant distal inclination, protrusion of the anterior teeth, and increase in lower anterior facial height (LAFH) due to the clockwise mandibular rotation. After fixed orthodontic treatment, the maxillary incisors and the maxillary first premolars and first molars were returned to their pretreatment anteroposterior positions. Thus, at postdistalization, there was 2.1 mm of protrusion of the maxillary first molars, despite the anchorage reinforcement (Nance button and cervical headgear worn at night during fixed appliance therapy). However, at the end of treatment, all patients had Class I molar relationships. The pendulum appliance followed by fixed orthodontic treatment corrected the Class II sagittal relationship, especially due to the dentoalveolar changes secondary to the spontaneous mandibular growth in the anterior direction during fixed appliance treatment.
Inverted pendulum as low-frequency pre-isolation for advanced gravitational wave detectors
International Nuclear Information System (INIS)
Takamori, A.; Raffai, P.; Marka, S.; DeSalvo, R.; Sannibale, V.; Tariq, H.; Bertolini, A.; Cella, G.; Viboud, N.; Numata, K.; Takahashi, R.; Fukushima, M.
2007-01-01
We have developed advanced seismic attenuation systems for Gravitational Wave (GW) detectors. The design consists of an Inverted Pendulum (IP) holding stages of Geometrical Anti-Spring Filters (GASF) and pendula, which isolate the test mass suspension from ground noise. The ultra-low-frequency IP suppresses the horizontal seismic noise, while the GASF suppresses the vertical ground vibrations. The three legs of the IP are supported by cylindrical maraging steel flexural joints. The IP can be tuned to very low frequencies by carefully adjusting its load. As a best result, we have achieved an ultra low, ∼12 mHz pendulum frequency for the system prototype made for Advanced LIGO (Laser Interferometer Gravitational Wave Observatory). The measured quality factor, Q, of this IP, ranging from Q∼2500 (at 0.45 Hz) to Q∼2 (at 12 mHz), is compatible with structural damping, and is proportional to the square of the pendulum frequency. Tunable counterweights allow for precise center-of-percussion tuning to achieve the required attenuation up to the first leg internal resonance (∼60 Hz for advanced LIGO prototype). All measurements are in good agreement with our analytical models. We therefore expect good attenuation in the low-frequency region, from ∼0.1to ∼50 Hz, covering the micro-seismic peak. The extremely soft IP requires minimal control force, which simplifies any needed actuation
Energy Technology Data Exchange (ETDEWEB)
Tapia-Vine, M.; Pedrosa, I.; Escribano, N. [Hospital Clinico San Carlos (Spain)
2000-07-01
Isolated torsion of the fallopian tube is an uncommon entity. Given the difficulties involved in the preoperative diagnosis, the ultrasound findings characteristic of this anomaly are not widely known. We present a case of tubal torsion associated with a cyst, describing the ultrasound images in our case and those reported in the literature. (Author) 18 refs.
Testicular torsion and weather conditions: analysis of 21,289 cases in Brazil
Directory of Open Access Journals (Sweden)
Fernando Korkes
2012-04-01
Full Text Available PURPOSE: The hypothesis of association between testicular torsion and hyperactive cremasteric reflex, worsened by cold weather, has not been proved. Thirteen studies in the literature evaluated this issue, with inconclusive results. The aim of the present study was to evaluate the seasonality of testicular torsion in a large subset of patients surgically treated in Brazil, and additionally to estimate the incidence of testicular torsion. MATERIALS AND METHODS: Brazilian Public Health System Database was assessed from 1992-2010 to evaluate hospital admissions associated with treatment of testicular torsion. Average monthly temperature between 1992-2010 was calculated for each region. RESULTS: We identified 21,289 hospital admissions for treatment of testicular torsion. There was a higher number of testicular torsions during colder months (p = 0.002. To estimate the incidence of testicular torsion, we have related our findings to data from the last Brazilian census (2010. In 2010, testicular torsion occurred in 1.4:100,000 men in Brazil. CONCLUSIONS:Testicular torsion occurred at an annual incidence of approximately 1.4:100,000 men in Brazil in 2010. Seasonal variations do occur, with a significant increase of events during winter. Our findings support the theory of etiological role of cold weather to the occurrence of testicular torsion. Strategies to prevent these events can be based on these findings.
International Nuclear Information System (INIS)
Takatsu, Hideyuki; Yamamoto, Masahiro; Shimizu, Masatsugu; Suzuki, Kazuo; Sonobe, Tadashi; Hayashi, Yuzo; Mizuno, Gen-ichiro.
1984-01-01
Torsional fatigue strength of the welded bellows was evaluated experimentally, aiming the application to a port of a fusion device. The welded bellows revealed elastic torsional buckling and spiral distorsion even under a small angle of torsion. Twisting load never leads the welded bellows to fracture easily so far as the angle of torsion is not excessively large, and the welded bellows has the torsional fatigue strength much larger than that expected so far. Two formulae were proposed to evaluate the stress of the welded bellows under the forced angle of torsion; shearing stress evaluation formula in the case that torsional buckling does not occur and the axial bending stress evaluation formula in the case that torsional buckling occurs. And the results of the torsional fatigue experiments showed that the former is reasonably conservative and simulates the actual behavior of the welded bellows better than the latter in the high cycle fatigue region and vice versa in the low cycle fatigue region from the viewpoint of the mechanical design. The present evaluation method of the torsional fatigue strength was applied to the welded bellows for the port of the JT-60 vacuum vessel and its structural integrity was confirmed under the design load condition. (author)
Omental torsion in a captive polar bear (Ursus maritimus).
Mendez-Angulo, Jose L; Funes, Francisco J; Trent, Ava M; Willette, Michelle; Woodhouse, Kerry; Renier, Anna C
2014-03-01
This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2-day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen.
Coupled Torsional and Bending Vibrations of Actively Controlled Drillstrings
YIGIT, A. S.; CHRISTOFOROU, A. P.
2000-06-01
The dynamics of actively controlled drillstrings is studied. The equations of motion are derived using a lumped parameter model in which the coupling between torsional and bending vibrations is considered. The model also includes the dynamics of the rotary drive system which contains the rotary table, the gearbox and an armature controlled DC motor. The interactions between the drillstring and the borehole which are considered, include the impacts of collars with the borehole wall as well as bit rotation-dependent weight and torque on bit (WOB and TOB). Simulation results obtained by numerically solving the equations of motion are in close qualitative agreement with field and laboratory observations regarding stick-slip oscillations. A linear quadratic regulator (LQR) controller is designed based on a linearized model and is shown to be effective in eliminating this type of oscillations. It is also shown that for some operational parameters the control action may excite large bending vibrations due to coupling with the torsional motion.
Torsion of a Wandering Spleen Presenting as Acute Abdomen
International Nuclear Information System (INIS)
Chauhan, Narvir Singh; Kumar, Satish
2016-01-01
Wandering spleen is a rare condition which if uncorrected, can result in torsion and infarction. Clinical presentation of a wandering spleen can vary from asymptomatic abdominal mass to acute abdominal pain. Radiological investigations play a pivotal role in diagnosis as the clinical diagnosis is usually impossible. We present a case of wandering spleen with torsion and complete infarction that occurred in a 32-year-old multiparous female. The diagnosis was established preoperatively on colour Doppler and CT of the abdomen with subsequent confirmation on surgery. Wandering spleen is a rare clinical condition which can present as acute abdomen. An increased awareness of this entity together with the timely use of ultrasound and CT of the abdomen can play an important role in preoperative diagnosis and surgical management
Longitudinal and torsional vibrations in rotors with transverse cracks
International Nuclear Information System (INIS)
Theis, W.
1990-01-01
In a rotating shaft with a crack, the bending, longitudinal and torsional degrees of freedom are linked. This paper presents a crack model which for the first time takes all six beam degrees of freedom into account for the open crack. The statements lead to a finite rigidity matrix and a transition matrix for a crack beam element. The model concepts known to date can be consistently generated as special cases from the new crack model. Depending on the motion condition, equations of motion with non-linear or periodically time-variant character are obtained. The longitudinal and torsional vibration behaviour under weight-dominant conditions are examined more intensively with the example of a large turbine. It is shown that the vibration components in harmony with the rotation can be used to identify the location and depth of the crack. (orig.) With 88 figs [de
TORSIONAL DEFORMATION AND FATIGUE BEHAVIOUR OF 6061 ALUMINIUM ALLOY
Directory of Open Access Journals (Sweden)
marini marno
2012-02-01
Full Text Available Torsional deformation and fatigue behaviour of both solid and thin-walled tubular specimens were made from as-received and heat treated 6061 aluminium alloy were studied. 6061 aluminium alloy have been widely used as a candidate material in automobile, aerospace, aircraft and structural application because of their superior mechanical properties such as high strength to weight ratio, good ductility and others. The differences in cyclic deformation and fatigue behaviours between round and solid specimens where a stress gradient exist, and thin-walled tubular specimens where a uniform stress state is commonly assumed, are also discussed. Von Mises and Tresca criteria has been used to predict the monotonic and cyclic deformation curve and compared to the torsional data obtained from the experiment. The S-N curve was used to present and evaluate the fatigue life of the specimens. Through fractographic analysis, failure criteria of fracture surfaces were observed and discussed.
The Torsion of Members Having Sections Common in Aircraft Construction
Trayer, George W; March, H W
1930-01-01
Within recent years a great variety of approximate torsion formulas and drafting-room processes have been advocated. In some of these, especially where mathematical considerations are involved, the results are extremely complex and are not generally intelligible to engineers. The principal object of this investigation was to determine by experiment and theoretical investigation how accurate the more common of these formulas are and on what assumptions they are founded and, if none of the proposed methods proved to be reasonable accurate in practice, to produce simple, practical formulas from reasonably correct assumptions, backed by experiment. A second object was to collect in readily accessible form the most useful of known results for the more common sections. Formulas for all the important solid sections that have yielded to mathematical treatment are listed. Then follows a discussion of the torsion of tubular rods with formulas both rigorous and approximate.
MR evaluation of femoral neck version and tibial torsion
International Nuclear Information System (INIS)
Koenig, James Karl; Dwek, Jerry R.; Pring, Maya E.
2012-01-01
Abnormalities of femoral neck version have been associated with a number of hip abnormalities in children, including slipped capital femoral epiphysis, proximal femoral focal deficiency, coxa vara, a deep acetabulum and, rarely, developmental dysplasia of the hip. Orthopedic surgeons also are interested in quantifying the femoral neck anteversion or retroversion in children especially to plan derotational osteotomies. Historically, the angle of femoral version and tibial torsion has been measured with the use of radiography and later by CT. Both methods carry with them the risks associated with ionizing radiation. Techniques that utilize MR are used less often because of the associated lengthy imaging times. This article describes a technique using MRI to determine femoral neck version and tibial torsion with total scan times of approximately 10 min. (orig.)
In vitro transcription of a torsionally constrained template
DEFF Research Database (Denmark)
Bentin, Thomas; Nielsen, Peter E
2002-01-01
of torsionally constrained DNA by free RNAP. We asked whether or not a newly synthesized RNA chain would limit transcription elongation. For this purpose we developed a method to immobilize covalently closed circular DNA to streptavidin-coated beads via a peptide nucleic acid (PNA)-biotin conjugate in principle......RNA polymerase (RNAP) and the DNA template must rotate relative to each other during transcription elongation. In the cell, however, the components of the transcription apparatus may be subject to rotary constraints. For instance, the DNA is divided into topological domains that are delineated...... constrained. We conclude that transcription of a natural bacterial gene may proceed with high efficiency despite the fact that newly synthesized RNA is entangled around the template in the narrow confines of torsionally constrained supercoiled DNA....
Quartz crystal microbalance based on torsional piezoelectric resonators
International Nuclear Information System (INIS)
Buecking, W.; Du, B.; Turshatov, A.; Koenig, A. M.; Reviakine, I.; Bode, B.; Johannsmann, D.
2007-01-01
A quartz crystal microbalance (QCM) is described, which is based on a torsional resonator, rather than a conventional thickness-shear resonator. Typical applications are measurements of film thickness in the coating industry and monitoring of biofouling. The torsional QCM is about a factor of 100 less sensitive than the conventional QCM. On the other hand, it can probe film thicknesses in the range of hundreds of microns, which is impossible with the conventional QCM due to viscoelastic artifacts. Data acquisition and data analysis proceed in analogy to the conventional QCM. An indicator of the material's softness can be extracted from the bandwidth of the resonance. Within the small-load approximation, the frequency shift is independent of whether the sample is applied to the face or to the side of the cylinder. Details of the geometry matter if the viscoelastic properties of the sample are of interest
A torsional artificial muscle from twisted nitinol microwire
Mirvakili, Seyed M.; Hunter, Ian W.
2017-04-01
Nitinol microwires of 25 μm in diameter can have tensile actuation of up to 4.5% in less than 100 ms. A work density of up to 480 MPa can be achieved from these microwires. In the present work, we are showing that by twisting the microwires in form of closed-loop two-ply yarn we can create a torsional actuator. We achieved a revisable torsional stroke of 46°/mm with peak rotational speed of up to 10,000 rpm. We measured a gravimetric torque of up to 28.5 N•m/kg which is higher than the 3 - 6 N•m/kg for direct-drive commercial electric motors. These remarkable performance results are comparable to those of guest-infiltrated carbon nanotube twisted yarns.
Secondary torsion of vermiform appendix with mesoappendiceal lipoma.
Grebic, Damir; Lovasic, Franjo; Benjak, Indira; Lovasic, Ingrid
2015-01-01
A torsion of the vermiform appendix with a mesoappendiceal lipoma is a rare condition. It is also a rare cause of acute abdomen, as such, the condition is diagnosed during surgery. This case report presents a 70-year-old male patient with lower right abdominal pain and signs of acute abdomen with an increased peripheral blood leukocyte count. An ultrasound examination revealed a mass of 9.6 cm2, which was suggested to be a perityphlitic abscess. An emergency operation was indicated, as the patient had clinical signs of acute abdomen. Laparotomy via a pararectal incision revealed the cause of the pain to be a torsion of the vermiform appendix caused by a mesoappendiceal lipoma. The apex of the appendix was perforated, which caused circumscript peritonitis. Both an appendectomy and an extirpation of the tumor were performed, and a surgical drain was placed in the wound, yielding an excellent postoperative clinical outcome.
Global aspects of symmetries in sigma models with torsion
International Nuclear Information System (INIS)
Papadopoulos, G.; Imperial Coll. of Science and Technology, London
1994-07-01
It is shown that non-trivial topological sectors can prevent the quantum mechanical implementation of the symmetries of the classical field equations of sigma models with torsion. The associated anomaly is computed, and it is shown that it depends on the homotopy class of the topological sector of the theory and the group action on the sigma model manifold that generates the symmetries of the classical field equations. (orig.)
Test rig for tension-torsion at high temperature
International Nuclear Information System (INIS)
Policella, H.; Pacou, D.
1988-01-01
An improved version of Tension-Torsion test rig at high temperature (1,000 0 C) is described. Damage under Multiaxial loading, experimental methods have been developed concerning both extensometric measures and induction heating application. First experimental results are presented for AISI316 nuclear steel at 600 0 C and INCO718 alloy at 650 and 550 0 C. During these tests, the Multiaxiality effect is investigated following proportional or non proportional strain (or stress) paths (phase or out of phase) [fr
Calibration of combined bending-torsion fatigue reliability data reduction
Kececioglu, D.; Mcconnell, J. B.
1969-01-01
The combined bending-torsion fatigue reliability research machines are described. Three such machines are presently in operation. The calibration of these machines is presented in depth. Fatigue data generated with these machines for SAE 4340 steel grooved specimens subjected to reversed bending and steady torque loading are given. The data reduction procedure is presented. Finally, some comments are made about notch sensitivity and stress concentration as applied to combined fatigue.
Portal Venous Thrombosis Developing after Torsion of a Wandering ...
African Journals Online (AJOL)
2017-03-06
Mar 6, 2017 ... L, Mullineris B, et al. Laparoscopic transperitoneal left adrenalectomy and wandering spleen risk. JSLS 2014:18-pii: e2014.00278. 5. Koca B, Çınar H, İA Tarım, Güngör BB. Torsion of the wandering spleen: A rare case of acute abdominal causing. Gulhane Med J 2013;55:51-53. 6. Herman TE, Siegel MJ.
On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue
Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.
2016-01-01
Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \
Ultrahigh torsional stiffness and strength of boron nitride nanotubes.
Garel, Jonathan; Leven, Itai; Zhi, Chunyi; Nagapriya, K S; Popovitz-Biro, Ronit; Golberg, Dmitri; Bando, Yoshio; Hod, Oded; Joselevich, Ernesto
2012-12-12
We report the experimental and theoretical study of boron nitride nanotube (BNNT) torsional mechanics. We show that BNNTs exhibit a much stronger mechanical interlayer coupling than carbon nanotubes (CNTs). This feature makes BNNTs up to 1 order of magnitude stiffer and stronger than CNTs. We attribute this interlayer locking to the faceted nature of BNNTs, arising from the polarity of the B-N bond. This property makes BNNTs superior candidates to replace CNTs in nanoelectromechanical systems (NEMS), fibers, and nanocomposites.
Compactification over coset spaces with torsion and vanishing cosmological constant
International Nuclear Information System (INIS)
Batakis, N.A.
1989-01-01
We consider the compactification of ten-dimensional Einstein-Yang-Mills theories over non-symmetric, six-dimensional homogeneous coset spaces with torsion. We examine the Einstein-Yang-Mills equations of motion requiring vanishing cosmological constant at ten and four dimensions and we present examples of compactifying solutions. It appears that the introduction of more than one radii in the coset space, when possible, may be mandatory for the existence of compactifying solutions. (orig.)
Compactification over coset spaces with torsion and vanishing cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Batakis, N.A.; Farakos, K.; Koutsoumbas, G.; Zoupanos, G.; Kapetanakis, D.
1989-04-13
We consider the compactification of ten-dimensional Einstein-Yang-Mills theories over non-symmetric, six-dimensional homogeneous coset spaces with torsion. We examine the Einstein-Yang-Mills equations of motion requiring vanishing cosmological constant at ten and four dimensions and we present examples of compactifying solutions. It appears that the introduction of more than one radii in the coset space, when possible, may be mandatory for the existence of compactifying solutions.
Elasto-plastic torsion problem as an infinity Laplace's equation
Directory of Open Access Journals (Sweden)
Ahmed Addou
2006-12-01
Full Text Available In this paper, we study a perturbed infinity Laplace's equation, the perturbation corresponds to an Leray-Lions operator with no coercivity assumption. We consider the case where data are distributions or $L^{1}$ elements. We show that this problem has an unique solution which is the solution to the variational inequality arising in the elasto-plastic torsion problem, associated with an operator $A$.
Torsion and curvature in higher dimensional supergravity theories
International Nuclear Information System (INIS)
Smith, A.W.; Pontificia Univ. Catolica do Rio de Janeiro
1983-01-01
This work is an extension of Dragon's theorems to higher dimensional space-time. It is shown that the first set of Bianchi identities allow us to express the curvature components in terms of torsion components and its covariant derivatives. It is also shown that the second set of Bianchi identities does not give any new information which is not already contained in the first one. (Author) [pt
Review of gastric torsion in eight guinea pigs (Cavia porcellus).
Nógrádi, Anna Linda; Cope, Iain; Balogh, Márton; Gál, János
2017-12-01
The authors present eight cases of gastric dilatation and volvulus (GDV) in guinea pigs from the Department and Clinic of Exotic Animal and Wildlife Medicine, University of Veterinary Medicine, Budapest, Hungary between 2012 and 2016. Seven animals were operated on and two survived. Gastric torsion has been noted in many mammalian species. Gastric volvulus has a high morbidity and high mortality rate with a guarded to poor prognosis in all of these species. How GDV develops is still not widely understood. Postmortem examinations, in both our cases and previously reported cases, have failed to reveal the exact causes of the gastric torsions. The aetiology of gastric torsion in guinea pigs is probably multifactorial. Feeding fewer meals per day, eating rapidly, decreased food particle size, exercise, stress after a meal, competition, age, and an aggressive or fearful temperament, are all likely and potential risk factors for GDV development in a similar fashion to dogs. Sex, breeding, dental diseases, anatomical abnormalities, pain and pregnancy may also be contributing factors.
Stresses and strains under torsion of polymeric parts
Directory of Open Access Journals (Sweden)
Kulyk T.I.
2016-12-01
Full Text Available The article is devoted to the determination of stress arising during deformation of polymeric parts, namely, under torsion. Analytical methods with a graphical representation of are used in the paper. Because the elastic properties of polymeric materials do not obey Hooke's law, the use of classical methods of applied mechanics for description of such parts leads to errors in calculation results. The process of deformation of polymeric beams under torsion is analyzed. The mathematical model is evolved to describe the process of torsion of solid and hollow beams of circular cross section. The expressions for shear stress distribution along the radius of the beam and calculating the angle of twist of beam’s sections under torque are obtained, given the nature of dependence between strains and stresses for the polymeric material. Graphic dependencies are built, showing the results of calculation of shear stresses and deformations of beams at different values of torque. The mathematical model is built using a power relationship between stress and deformation of the polymer material. The results can be used for the design of structural elements of machines and appliances, building constructions, products of light industry.
On discrete symmetries and torsion homology in F-theory
Energy Technology Data Exchange (ETDEWEB)
Mayrhofer, Christoph [Arnold-Sommerfeld-Center, Ludwig-Maximilians-Universität München,München (Germany); Palti, Eran; Till, Oskar; Weigand, Timo [Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg,Heidelberg (Germany)
2015-06-04
We study the relation between discrete gauge symmetries in F-theory compactifications and torsion homology on the associated Calabi-Yau manifold. Focusing on the simplest example of a ℤ{sub 2} symmetry, we show that there are two physically distinct ways that such a discrete gauge symmetry can arise. First, compactifications of M-Theory on Calabi-Yau threefolds which support a genus-one fibration with a bi-section are known to be dual to six-dimensional F-theory vacua with a ℤ{sub 2} gauge symmetry. We show that the resulting five-dimensional theories do not have a ℤ{sub 2} symmetry but that the latter emerges only in the F-theory decompactification limit. Accordingly the genus-one fibred Calabi-Yau manifolds do not exhibit torsion in homology. Associated to the bi-section fibration is a Jacobian fibration which does support a section. Compactifying on these related but distinct varieties does lead to a ℤ{sub 2} symmetry in five dimensions and, accordingly, we find explicitly an associated torsion cycle. We identify the expected particle and membrane system of the discrete symmetry in terms of wrapped M2 and M5 branes and present a field-theory description of the physics for both cases in terms of circle reductions of six-dimensional theories. Our results and methods generalise straightforwardly to larger discrete symmetries and to four-dimensional compactifications.
Directory of Open Access Journals (Sweden)
Javed Hussain Farooqui
2016-05-01
Full Text Available AIM: To compare the accuracy of two different methods of preoperative marking for toric intraocular lens (IOL implantation, bubble marker versus pendulum marker, as a means of establishing the reference point for the final alignment of the toric IOL to achieve an outcome as close as possible to emmetropia. METHODS: Toric IOLs were implanted in 180 eyes of 110 patients. One group (55 patients had preoperative marking of both eyes done with bubble marker (ASICO AE-2791TBL and the other group (55 patients with pendulum marker (Rumex(3-193. Reference marks were placed at 3-, 6-, and 9-o'clock positions on the limbus. Slit-lamp photographs were analyzed using Adobe Photoshop (version 7.0. Amount of alignment error (in degrees induced in each group was measured. RESULTS: Mean absolute rotation error in the preoperative marking in the horizontal axis was 2.42±1.71 in the bubble marker group and 2.83±2.31in the pendulum marker group (P=0.501. Sixty percent of the pendulum group and 70% of the bubble group had rotation error ≤3 (P=0.589, and 90% eyes of the pendulum group and 96.7% of the bubble group had rotation error ≤5 (P=0.612. CONCLUSION: Both preoperative marking techniques result in approximately 3 of alignment error. Both marking techniques are simple, predictable, reproducible and easy to perform.
Directory of Open Access Journals (Sweden)
Duka Adrian-Vasile
2011-12-01
Full Text Available This paper examines the development of a genetic adaptive fuzzy control system for the Inverted Pendulum. The inverted pendulum is a classical problem in Control Engineering, used for testing different control algorithms. The goal is to balance the inverted pendulum in the upright position by controlling the horizontal force applied to its cart. Because it is unstable and has a complicated nonlinear dynamics, the inverted pendulum is a good testbed for the development of nonconventional advanced control techniques. Fuzzy logic technique has been successfully applied to control this type of system, however most of the time the design of the fuzzy controller is done in an ad-hoc manner, and choosing certain parameters (controller gains, membership functions proves difficult. This paper examines the implementation of an adaptive control method based on genetic algorithms (GA, which can be used on-line to produce the adaptation of the fuzzy controller’s gains in order to achieve the stabilization of the pendulum. The performances of the proposed control algorithms are evaluated and shown by means of digital simulation.
Tensile and Torsional Structural Properties of the Native Scapholunate Ligament.
Pang, Eric Quan; Douglass, Nathan; Behn, Anthony; Winterton, Matthew; Rainbow, Michael J; Kamal, Robin N
2018-02-17
The ideal material for reconstruction of the scapholunate interosseous ligament (SLIL) should replicate the mechanical properties of the native SLIL to recreate normal kinematics and prevent posttraumatic arthritis. The purpose of our study was to evaluate the cyclic torsional and tensile properties of the native SLIL and load to failure tensile properties of the dorsal SLIL. The SLIL bone complex was resected from 10 fresh-frozen cadavers. The scaphoid and lunate were secured in polymethylmethacrylate and mounted on a test machine that incorporated an x-y stage and universal joint, which permitted translations perpendicular to the rotation/pull axis as well as nonaxial angulations. After a 1 N preload, specimens underwent cyclic torsional testing (±0.45 N m flexion/extension at 0.5 Hz) and tensile testing (1-50 N at 1 Hz) for 500 cycles. Lastly, the dorsal 10 mm of the SLIL was isolated and displaced at 10 mm/min until failure. During intact SLIL cyclic torsional testing, the neutral zone was 29.7° ± 6.6° and the range of rotation 46.6° ± 7.1°. Stiffness in flexion and extension were 0.11 ± 0.02 and 0.12 ± 0.02 N m/deg, respectively. During cyclic tensile testing, the engagement length was 0.2 ± 0.1 mm, the mean stiffness was 276 ± 67 N/mm, and the range of displacement was 0.4 ± 0.1 mm. The dorsal SLIL displayed a 0.3 ± 0.2 mm engagement length, 240 ± 65 N/mm stiffness, peak load of 270 ± 91 N, and displacement at peak load of 1.8 ± 0.3 mm. We report the torsional properties of the SLIL. Our novel test setup allows for free rotation and translation, which reduces out-of-plane force application. This may explain our observation of greater dorsal SLIL load to failure than previous reports. By matching the natural ligament with respect to its tensile and torsional properties, we believe that reconstructions will better restore the natural kinematics of the wrist and lead to improved outcomes. Future clinical studies should aim to investigate this
Wang, Y. M.; Xu, W. C.; Wu, S. Q.; Chai, C. W.; Liu, X.; Wang, S. H.
2018-03-01
The torsional oscillation is the dominant vibration form for the impression cylinder of printing machine (printing cylinder for short), directly restricting the printing speed up and reducing the quality of the prints. In order to reduce torsional vibration, the active control method for the printing cylinder is obtained. Taking the excitation force and moment from the cylinder gap and gripper teeth open & closing cam mechanism as variable parameters, authors establish the dynamic mathematical model of torsional vibration for the printing cylinder. The torsional active control method is based on Particle Swarm Optimization(PSO) algorithm to optimize input parameters for the serve motor. Furthermore, the input torque of the printing cylinder is optimized, and then compared with the numerical simulation results. The conclusions are that torsional vibration active control based on PSO is an availability method to the torsional vibration of printing cylinder.
Stevens, Peter M.; Gililland, Jeremy M.; Anderson, Lucas A.; Mickelson, Jennifer B.; Nielson, Jenifer; Klatt, Joshua W.
2013-01-01
Torsional deformities of the femur and/or tibia often go unrecognized in adolescents and adults who present with anterior knee pain, and patellar maltracking or instability. While open and arthroscopic surgical techniques have evolved to address these problems, unrecognized torsion may compromise the outcomes of these procedures. We collected a group of 16 consecutive patients (23 knees), with mean age of 17, who had undergone knee surgery before torsion was recognized and subsequently treate...
3D Curves With a Prescribed Curvature and Torsion for a Flying Robot
International Nuclear Information System (INIS)
Bestaoui, Yasmina
2008-01-01
The objective of this paper is to generate a desired flight path to be followed by an flying robot. A curve with discontinuous curvature and torsion is not appropriate for smooth motions for any vehicle architecture. Three different classes of curves are presented. First, constant curvature and torsion followed by a linear variation versus the curvilinear abscissa then a quadratic variation. Finally, the problem of maneuvers between two trim helices of different curvature and torsion is tackled with
Nonuniform Shear Strains in Torsional Kolsky Bar Tests on Soft Specimens
2015-02-01
this problem can be inferred from the paper [Hill and Lee 1989], which treats a slightly different problem, namely combined compression and torsion of...well before the torsional stress increases. This effect cannot be due to bending waves or longitudinal waves that might be generated in the incident...292. [Hill and Lee 1989] J. M. Hill and A. I. Lee, “ Combined compression and torsion of circular cylindrical pads of rubber”, J. Mech. Phys. Solids 37:2
Appendiceal torsion associated with undescended caecum: a case report and review of the literature
Dimitriadis, Panagiotis A; Makar, Ragai R; Randall, Jon K; Ramus, James
2012-01-01
Torsion of the vermiform appendix is a rare disorder that causes symptoms similar to those of acute appendicitis. Primary and secondary causes of appendiceal torsion have been reported in the literature. Laparoscopy appears to be the most appropriate modality for diagnosis and treatment where the condition is suspected. To our knowledge this is the first case of appendiceal torsion in an adult causing right upper quadrant pain related to caecal malposition. PMID:23010467
Variable friction pendulum system for seismic isolation of liquid storage tanks
Energy Technology Data Exchange (ETDEWEB)
Panchal, V.R. [Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India); Jangid, R.S. [Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)], E-mail: rsjangid@civil.iitb.ac.in
2008-06-15
Earthquake response of liquid storage steel tanks isolated with variable friction pendulum system (VFPS) is investigated under normal component of six recorded near-fault ground motions. The continuous liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The corresponding stiffness constants associated with these lumped masses are worked out depending upon the properties of the tank wall and liquid mass. The governing equations of motion of the tanks isolated with variable friction pendulum system are derived and solved by Newmark's step-by-step method assuming linear variation of acceleration over small time interval. In order to verify the effectiveness of the VFPS in tanks, the seismic response of tanks isolated with VFPS is compared with that of the same tanks isolated using the conventional friction pendulum system (FPS). Furthermore, a parametric study is also carried out to critically examine the behaviour of tanks isolated with VFPS. The various important parameters considered are the tank aspect ratio, the isolation period and initial time period of the VFPS. In addition, the seismic response of tanks isolated with VFPS under trigonometric cycloidal pulses is also investigated. From these investigations, it is concluded that with the installation of VFPS in tanks, the seismic response of tanks during near-fault ground motions can be controlled within a desirable range. Finally, it is also observed that the response of tanks isolated with VFPS under the near-fault ground motions and trigonometric cycloidal pulses matches well only when the isolation period reaches high values.
Directory of Open Access Journals (Sweden)
Ashwani Kharola
2016-09-01
Full Text Available Inverted pendulum on cart belongs to a class of highly non-linear, multivariable and complex system which is currently a keen area of interest for researchers in the field of control engineering and robotics. This paper considers stabilisation and control of inverted pendulum on cart moving on an inclined surface. The task of controlling inverted pendulum on inclined surface is much difficult as compared to that moving on horizontal surface. An offline control of the proposed system has been successfully achieved using proportional-integral-derivative (PID and fuzzy controllers. A Matlab-Simulink model of the proposed system has been built using mathematical equations derived from Newton's second law. The study compares the proposed techniques in terms of settling time, overshoot, undershoot and steady state error. The simulation results are illustrated with the help of graphs and tables which confirms the validity of the proposed techniques.
Unusual cause of acute abdominal pain in a postmenopausal woman: adnexal torsion
Directory of Open Access Journals (Sweden)
Alper Biler
2016-03-01
Full Text Available Adnexal torsion is an infrequent but significant cause of acute lower abdominal pain in women. While adnexal torsion is generally considered in premenopausal women presenting with acute abdominal pain and a pelvic mass, it is a rare cause of acute abdominal pain during postmenopausal period. The diagnosis of adnexal torsion is often challenging due to nonspesific clinical, laboratory and physical examination findings. Causes of adnexal torsion is also different in premenopausal and postmenopausal women. While a simple functional cyst is often the cause of torsion in premenopausal women, it is more rarely the cause in postmenopausal women. Adnexal torsion is a surgical emergency. The surgery of adnexal torsion is performed either via conventional exploratory laparotomy or laparoscopic surgery. Adnexal torsion in postmenopausal women should be considered not only in the setting of sudden onset pain, but also in long-term abdominal discomfort. In this article, we presented a case with adnexal torsion that rarely cause acute abdominal pain in postmenopausal women. [Cukurova Med J 2016; 41(1.000: 167-170
Jeong, Byeong-Woo; Lim, Jang-Keun; Sinnott, Susan B.
2007-01-01
The tensile mechanical behavior of hollow and filled single-walled carbon nanotubes under tension or combined tension-torsion is examined using classical molecular dynamics simulations. These simulations indicate that the tensile strength under combined tension-torsion can be increased by filling the carbon nanotubes, and the amount of this increase depends on the kind of filling material. They also predict that the tensile strength under combined tension-torsion decreases linearly under applied torsion. The tensile strength can be modified by adjusting the system temperature and through chemical functionalization to the carbon nanotube walls.
Cyclic Sieving for torsion pairs in the cluster category of Dynkin type A_n
Kluge, Stefan; Rubey, Martin
2011-01-01
Recently, a combinatorial model for torsion pairs in the cluster category of Dynkin type A_n was introduced, and used to derive an explicit formula for their number. In this article we determine the number of torsion pairs that are invariant under b-fold application of Auslander-Reiten translation. It turns out that the set of torsion pairs together with Auslander-Reiten translation, and a natural q-analogue of the formula for the number of all torsion pairs exhibits the cyclic sieving phenom...
Torsion of a mucocele of the vermiform appendix: a case report and review of the literature.
Lee, Chang Ho; Lee, Min Ro; Kim, Jae-Chun; Kang, Myoung Jae; Jeong, Yeon Jun
2011-12-01
Torsion of a mucocele of the vermiform appendix is an extremely rare condition and also a rare cause of an acute abdomen with a clinical presentation that is indistinguishable from acute appendicitis, and thus, the condition is diagnosed during operation. Here, the authors describe the case of a 78-year-old female, who presented with intermittent abdominal pain. The appendix had a pelvic position and the torsion was counterclockwise. In addition, the torsion was associated with mucocele of the appendix, which was considered a secondary factor of torsion. Appendectomy and drainage were performed.
Control design on the basis of approximate nonlinear models: the inverted pendulum example
DEFF Research Database (Denmark)
Jouffroy, Jerome; Lottin, Jacques
dealt with control of some classes of nonlinear systems. One of these families concerns flat systems for which it is possible to design reference trajectories that are admissible both for state variables and control input. However nonlinear plants may not exhibit such flatness properties since analysis...... is done in the whole state space. Since in many situations the process evolution is confined in a reduced domain, one solution consists in building an equivalent nonlinear model which exhibits flatness properties in order to use related control design tools. The inverted pendulum system is used...
Oscillations Control of Rocking-Block-Type Buildings by the Addition of a Tuned Pendulum
Directory of Open Access Journals (Sweden)
Luca Collini
2016-01-01
Full Text Available This study deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to reduce oscillations. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method, and dry friction has also been considered. From the analytical/numerical simulations, we derive some important conclusions, providing us with the tools suitable for the design of absorbers in practical cases.
Directory of Open Access Journals (Sweden)
Te-Jen Su
2016-12-01
Full Text Available The objective of this article is to optimize parameters of a hybrid sliding mode controller based on fireworks algorithm for a nonlinear inverted pendulum system. The proposed controller is a combination of two modified types of the classical sliding mode controller, namely, baseline sliding mode controller and fast output sampling discrete sliding mode controller. The simulation process is carried out with MATLAB/Simulink. The results are compared with a published hybrid method using proportional–integral–derivative and linear quadratic regulator controllers. The simulation results show a better performance of the proposed controller.
Experimental analysis of the influence of damping on the resonance behavior of a spherical pendulum
Czech Academy of Sciences Publication Activity Database
Pospíšil, Stanislav; Fischer, Cyril; Náprstek, Jiří
2014-01-01
Roč. 78, č. 1 (2014), s. 371-390 ISSN 0924-090X R&D Projects: GA ČR(CZ) GC13-34405J Grant - others:NSC(TW) 101WFD0400131 Institutional support: RVO:68378297 Keywords : auto -parametric system * experimental verification * spherical pendulum * stability of semi-trivial solution Subject RIV: JM - Building Engineering Impact factor: 2.849, year: 2014 http://link.springer.com/article/10.1007%2Fs11071-014-1446-6#page-1