On the Possibility to Construct Gravitational Eye

NASA Astrophysics Data System (ADS)

Chen, Ying-Tian

2007-05-01

The possibility of modifying a conventional Cavendish torsion pendulum into a half-armed pendulum oscillator to measure the horizontal gravitational acceleration is discussed. A new kind of gravitational detector, gravieye, as we named, can be made by a proper combination of such oscillators to ``see'' remote objects and to be used, e.g. to detect the movement of huge mass at a long distance.

How far can Tarzan jump?

NASA Astrophysics Data System (ADS)

Shima, Hiroyuki

2012-11-01

The tree-based rope swing is a popular recreational facility, often installed in outdoor areas. Hanging from a rope, users drop from a high platform and then swing at great speed like ‘Tarzan’, finally jumping ahead to land on the ground. The question naturally arises, how far can Tarzan jump using the swing? In this paper, I present an introductory analysis of the mechanics of the Tarzan swing, a large pendulum-like swing with Tarzan himself attached as weight. This enables determination of how much further forward Tarzan can jump using a given swing apparatus. The discussion is based on elementary mechanics and is, therefore, expected to provide rich opportunities for investigations using analytic and numerical methods.

The Electrostatic Gavimeter: An Alternative Way of Measuring Gravitational Acceleration

NASA Astrophysics Data System (ADS)

Kashinski, David

2005-03-01

In the past, Earth’s gravitational acceleration g has been measured in many ways, including the use of a pendulum as well as other models involving the use of a mass and a spring. We have designed a new method incorporating a spring with a capacitor and a voltmeter. This capacitor model still uses a hanging mass on a spring, but alters the method of determining the change in position of the spring due to the gravitational acceleration. We relate the change in position to the potential difference across the capacitor needed to cause a discharge through parallel plates. By relating this voltage directly to the gravitaional acceleration,a new method of measuring g is obtained.

Ultra-Stable Beacon Source for Laboratory Testing of Optical Tracking

NASA Technical Reports Server (NTRS)

Aso, Yoichi; Marka, Szabolcs; Kovalik, Joseph

2008-01-01

The ultra-stable beacon source (USBS) provides a laser-beam output with a very low angular jitter and can be used as an absolute angular reference to simulate a beacon in the laboratory. The laser is mounted on the top of a very short (approximately equal to 1 m) inverted pendulum (IP) with its optical axis parallel to the carbon fiber pendulum leg. The 85-cm, carbon fiber rods making up the leg are very lightweight and rigid, and are supported by a flex-joint at the bottom (see figure). The gimbal-mounted laser is a weight-adjustable load of about 1.5 kg with its center of rotation co-located with the center of percussion of the inverted pendulum. This reduces the coupling of transverse motion at the base of the pendulum to angular motion of the laser at the top. The inverted pendulum is mounted on a gimbal with its center of rotation coinciding with the pivot position of the inverted pendulum flexure joint. This reduces coupling of ground tilt at the inverted pendulum base to motion of the laser mounted at the top. The mass of the top gimbal is adjusted to give the pendulum a very low resonant frequency (approximately equal to 10 mHz) that filters transverse seismic disturbances from the ground where the base is attached. The motion of the IP is monitored by an optical-lever sensor. The laser light is reflected by the mirror on the IP, and then is detected by a quadrant photo-detector (QPD). The position of the beam spot on the QPD corresponds to the tilt of the IP. Damping of this motion is provided by two coil and magnet pairs. The bottom gimbal mount consists of two plates. The IP is mounted on the second plate. The first plate is supported by two posts through needles and can be rotated about the axis connecting the tips of the needles. The second plate hangs from the first plate and can be rotated about the axis perpendicular to the first plate. As a result, the second plate acts as a two-axis rotation stage. Its center of rotation is located at the effective bending point of the flex-joint. The second plate is pressed against two screw actuators by the weight of the IP. The screw actuators are orthogonal to each other and are used to adjust the inclination of the second plate. The actuators are driven by stepper motors. The whole IP system is housed in a box made of Lexan plastic plates to provide isolation from air currents and temperature variations. The signals from the sensors are processed and recorded with a PC using the xPC Target realtime environment of Math- Works. The control algorithms are written using the Simulink package from The MathWorks.

An automated digital data collection and analysis system for the Charpy Impact Tester

NASA Technical Reports Server (NTRS)

Kohne, Glenn S.; Spiegel, F. Xavier

1994-01-01

The standard Charpy Impact Tester has been modified by the addition of a system of hardware and software to improve the accuracy and consistency of measurements made during specimen fracturing experiments. An optical disc, light source, and detector generate signals that indicate the pendulum position as a function of time. These signals are used by a computer to calculate the velocity and kinetic energy of the pendulum as a function of its position.

Single and Multi-Pulse Low-Energy Conical Theta Pinch Inductive Pulsed Plasma Thruster Performance

NASA Technical Reports Server (NTRS)

Hallock, A. K.; Martin, A. K.; Polzin, K. A.; Kimberlin, A. C.; Eskridge, R. H.

2013-01-01

Impulse bits produced by conical theta-pinch inductive pulsed plasma thrusters possessing cone angles of 20deg, 38deg, and 60deg, were quantified for 500J/pulse operation by direct measurement using a hanging-pendulum thrust stand. All three cone angles were tested in single-pulse mode, with the 38deg model producing the highest impulse bits at roughly 1 mN-s operating on both argon and xenon propellants. A capacitor charging system, assembled to support repetitively-pulsed thruster operation, permitted testing of the 38deg thruster at a repetition-rate of 5 Hz at power levels of 0.9, 1.6, and 2.5 kW. The average thrust measured during multiple-pulse operation exceeded the value obtained when the single-pulse impulse bit is multiplied by the repetition rate.

Predictor-based control for an inverted pendulum subject to networked time delay.

PubMed

Ghommam, J; Mnif, F

2017-03-01

The inverted pendulum is considered as a special class of underactuated mechanical systems with two degrees of freedom and a single control input. This mechanical configuration allows to transform the underactuated system into a nonlinear system that is referred to as the normal form, whose control design techniques for stabilization are well known. In the presence of time delays, these control techniques may result in inadequate behavior and may even cause finite escape time in the controlled system. In this paper, a constructive method is presented to design a controller for an inverted pendulum characterized by a time-delayed balance control. First, the partial feedback linearization control for the inverted pendulum is modified and coupled with a state predictor to compensate for the delay. Several coordinate transformations are processed to transform the estimated partial linearized system into an upper-triangular form. Second, nested saturation and backstepping techniques are combined to derive the control law of the transformed system that would complete the design of the whole control input. The effectiveness of the proposed technique is illustrated by numerical simulations. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Assessment of Spasticity by a Pendulum Test in SCI Patients Who Exercise FES Cycling or Receive Only Conventional Therapy.

PubMed

Popovic-Maneski, Lana; Aleksic, Antonina; Metani, Amine; Bergeron, Vance; Cobeljic, Radoje; Popovic, Dejan B

2018-01-01

Increased muscle tone and exaggerated tendon reflexes characterize most of the individuals after a spinal cord injury (SCI). We estimated seven parameters from the pendulum test and used them to compare with the Ashworth modified scale of spasticity grades in three populations (retrospective study) to assess their spasticity. Three ASIA B SCI patients who exercised on a stationary FES bicycle formed group F, six ASIA B SCI patients who received only conventional therapy were in the group C, and six healthy individuals constituted the group H. The parameters from the pendulum test were used to form a single measure, termed the PT score, for each subject. The pendulum test parameters show differences between the F and C groups, but not between the F and H groups, however, statistical significance was limited due to the small study size. Results show a small deviation from the mean for all parameters in the F group and substantial deviations from the mean for the parameters in the C group. PT scores show significant differences between the F and C groups and the C and H groups and no differences between the F and C groups. The correlation between the PT score and Ashworth score was 0.88.

The epidemiology of injury in hang-gliding and paragliding.

PubMed

Rekand, Tiina

2012-01-01

Para- and hang-gliding are modern air sports that developed in the 20th century. Performers should possess technical skills and manage certified equipment for successful flight. Injuries may happen during the take-off, flight and landing. PubMed was searched using the search terms 'paragliding' and/or 'hang-gliding'. The reference lists of articles identified in the search strategy were also searched for relevant articles. The most common injuries are fractures, dislocations or sprains in the extremities, followed by spinal and head traumas. Multiple injuries after accidents are common. Collision with electrical wires may cause burn injuries. Fatal outcomes are caused by brain injuries, spinal cord injuries at the cervical level or aorta rupture. Accidents happen because of risk-taking behavior, lack of education or use of self-modified equipment. Observational studies have suggested the need for protection of the head, trunk and lower extremities. The measures proposed are often based on conclusions of observational studies and not proven through randomized studies. Better education along with focusing on possible risk factors will probably diminish the risks of hang- and paragliding. Large denominator-based case series, case-control and population-based studies are needed for assessment of the risks of hang- and paragliding. Copyright © 2012 S. Karger AG, Basel.

Initial Thrust Measurements of Marshall's Ion-ioN Thruster

NASA Technical Reports Server (NTRS)

Schloeder, Natalie R.; Scogin, Tyler; Liu, Thomas M.; Walker, Mitchell L. R.; Polzin, Kurt A.; Dankanich, John W.; Aanesland, Ane

2015-01-01

Electronegative ion thrusters are a variation of tradition gridded ion thruster technology differentiated by the production and acceleration of both positive and negative ions. Benefits of electronegative ion thrusters include the elimination of lifetime-limiting cathodes from the thruster architecture and the ability to generate appreciable thrust from both charge species. Following the continued development of electronegative ion thruster technology as exhibited by the PEGASES (Plasma Propulsion with Electronegative GASES) thruster, direct thrust measurements are required to push interest in electronegative ion thruster technology forward. For this work, direct thrust measurements of the MINT (Marshall's Ion-ioN Thruster) will be taken on a hanging pendulum thrust stand for propellant mixtures of Sulfur Hexafluoride and Argon at volumetric flow rates of 5-25 sccm at radio frequency power levels of 100-600 watts at a radio frequency of 13.56 MHz. Acceleration grid operation is operated using a square waveform bias of +/-300 volts at a frequency of 25 kHz.

Effects of conventional anchorage on premolar root development during treatment with a pendulum appliance.

PubMed

Kinzinger, Gero; Pantel, Cora; Ludwig, Björn; Gülden, Norbert; Glasl, Bettina; Lisson, Jörg

2010-07-01

By metrically analyzing orthopantomograms, we aimed in this study to retrospectively investigate whether maxillary premolars used as anchoring teeth during molar distalization with pendulum appliances would reveal inhibited root development. The upper molars were distalized with a modified pendulum appliance (Pendulum K) in 36 adolescents (14 males, 22 females, mean age 12.3 years). Mean treatment period was 19.5 weeks. Orthopantomograms of each patient were taken at the start (time point T1) and after completion of molar distalization (time point T2). The enlargement of the posterior region was ascertained individually quadrant by quadrant for each radiograph, followed by measurement of the vestibular tooth lengths of the premolars whose root development was for the most part not yet complete. To assess further root development in the premolar region, the differences were calculated between tooth lengths at the start and end of treatment. During treatment with the pendulum appliance a general increase in tooth lengths in the anchorage region was observed (1.37 +/- 1.70 mm, p<0.0001). Differentiated by dental age, we noted increases in tooth lengths of patients with second molars in the budding stage (patient group PG 1: 0.93 +/- 1.37 mm, p<0.0001) as well as of patients with fully-erupted second molars (patient group PG 2: 1.81 +/- 1.88 mm, p<0.0001). Both groups demonstrated greater increases in the second premolars than the first premolars; the increases group-wise were larger in PG 2 than PG 1. However, both the group comparison (PG 1 versus PG 2) and the side comparison (right versus left) (differentiated into first and second molars) showed no statistically relevant differences. Visual assessment of the radiographs revealed no evidence of treatment-related root deviations. A highly complex system of forces acts on the anchoring teeth during molar distalization with the conventionally-anchored Pendulum K. However, the Pendulum K appliance's specific biomechanics make it possible to transfer the reactive forces and moments to the anchorage unit so that they remain within the physiological range, allowing uninhibited premolar root development. This also applies after completed eruption of the second molars, when the treatment period and hence duration of exposure to the active and reactive forces and moments arising during molar distalization are comparatively increased.

Comparative evaluation of molar distalization therapy with erupted second molar: Segmented versus Quad Pendulum appliance.

PubMed

Caprioglio, Alberto; Cozzani, Mauro; Fontana, Mattia

2014-01-01

There are controversial opinions about the effect of erupted second molars on distalization of the first molars. Most of the distalizing devices are anchored on the first molars, without including second molars; so, differences between sequentially distalize maxillary molars (second molar followed by the first molar) or distalize second and first molars together are not clear. The aim of the study was to compare sequential versus simultaneous molar distalization therapy with erupted second molar using two different modified Pendulum appliances followed by fixed appliances. The treatment sample consisted of 35 class II malocclusion subjects, divided in two groups: group 1 consisted of 24 patients (13 males and 11 females) with a mean pre-treatment age of 12.9 years, treated with the Segmented Pendulum (SP) and fixed appliances; group 2 consisted of 11 patients (6 males and 5 females) with a mean pre-treatment age of 13.2 years, treated with the Quad Pendulum (QP) and fixed appliances. Lateral cephalograms were obtained before treatment (T1), at the end of distalization (T2), and at the end of orthodontic fixed appliance therapy (T3). A Student t test was used to identify significant between-group differences between T1 to T2, T2 to T3, and T1 to T3. QP and SP were equally effective in distalizing maxillary molars (3.5 and 4 mm, respectively) between T1 and T2; however, the maxillary first molar showed less distal tipping (4.6° vs. 9.6°) and more extrusion (1.1 vs. 0.2 mm) in the QP group than in the SP group, as well as the vertical facial dimension, which increased more in the QP group (1.2°) than in the SP group (0.7°). At T3, the QP group maintained greater increase in lower anterior facial height and molar extrusion and decrease in overbite than the SP group. Quad Pendulum seems to have greater increase in vertical dimension and molar extrusion than the Segmented Pendulum.

Helicopter vibration suppression using simple pendulum absorbers on the rotor blade

NASA Technical Reports Server (NTRS)

Pierce, G. A.; Hanouva, M. N. H.

1982-01-01

A comprehensive anaytical design procedure for the installation of simple pendulums on the blades of a helicopter rotor to suppress the root reactions is presented. A frequency response anaysis is conducted of typical rotor blades excited by a harmonic variation of spanwise airload distributions as well as a concentrated load at the tip. The results presented included the effect of pendulum tuning on the minimization of the hub reactions. It is found that a properly designed flapping pendulum attenuates the root out-of-plane force and moment whereas the optimum designed lead-lag pendulum attenuates the root in-plane reactions. For optimum pendulum tuning the parameters to be determined are the pendulum uncoupled natural frequency, the pendulum spanwise location and its mass. It is found that the optimum pendulum frequency is in the vicinity of the excitation frequency. For the optimum pendulum a parametric study is conducted. The parameters varied include prepitch, pretwist, precone and pendulum hinge offset.

Optical Kapitza pendulum

NASA Astrophysics Data System (ADS)

Jones, Philip H.; Smart, Thomas J.; Richards, Christopher J.; Cubero, David

2016-09-01

The Kapitza pendulum is the paradigm for the phenomenon of dynamical stabilization, whereby an otherwise unstable system achieves a stability that is induced by fast modulation of a control parameter. In the classic, macroscopic Kapitza pendulum, a rigid pendulum is stabilized in the upright, inverted pendulum using a particle confined in a ring-shaped optical trap, subject to a drag force via fluid flow and driven via oscillating the potential in a direction parallel to the fluid flow. In the regime of vanishing Reynold's number with high-frequency driving the inverted pendulum is no longer stable, but new equilibrium positions appear that depend on the amplitude of driving. As the driving frequency is decreased a yet different behavior emerges where stability of the pendulum depends also on the details of the pendulum hydrodynamics. We present a theory for the observed induced stability of the overdamped pendulum based on the separation of timescales in the pendulum motion as formulated by Kapitza, but with the addition of a viscous drag. Excellent agreement is found between the predicted behavior from the analytical theory and the experimental results across the range of pendulum driving frequencies. We complement these results with Brownian motion simulations, and we characterize the stabilized pendulum by both time- and frequency-domain analyses of the pendulum Brownian motion.

A Personal Navigation System Based on Inertial and Magnetic Field Measurements

DTIC Science & Technology

2010-09-01

MATLAB IMPLEMENTATION.................................................................74 G. A MODEL FOR PENDULUM MOTION SENSOR DATA...76 1. Pendulum Model for MATLAB Simulation....................................76 2. Sensor Data Generated with the Pendulum Model... PENDULUM ..................................................................................................88 I. FILTER PERFORMANCE WITH REAL PENDULUM DATA

Broadband pendulum energy harvester

NASA Astrophysics Data System (ADS)

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.

Dynamic characteristics of rotor blades with pendulum absorbers

NASA Technical Reports Server (NTRS)

Murthy, V. R.; Goglia, G. L.

1977-01-01

The point transmission matrix for a vertical plane pendulum on a rotating blade undergoing combined flapwise bending, and chordwise bending and torsion is derived. The equilibrium equation of the pendulum is linearized for small oscillations about the steady state. A FORTRAN program was written for the case of a vertical plane pendulum attached to a uniform blade with flapwise bending degree of freedom for cantilever boundary conditions. The frequency has a singular value right at the uncoupled pendulum natural frequency and thus introduces two frequencies corresponding to the nearest natural frequency of the blade without pendulum. In both of these modes it was observed that the pendulum deflection is large. One frequency can be thought of as a coupled pendulum frequency and the other as a coupled bending and pendulum frequency.

Application of hanging drop technique for stem cell differentiation and cytotoxicity studies.

PubMed

Banerjee, Meenal; Bhonde, Ramesh R

2006-05-01

The aim of our study is to explore the possibility of using an ancient method of culture technique- the hanging drop technique for stem cell differentiation and cytotoxicity testing. We demonstrate here a variety of novel applications of this age old technique not only to harness the differentiation potential of stem cells into specific lineages but also for cytotoxicity studies. Here we have prepared hanging drop cultures by placing 20 microl micro-drops of nutrient media and 10% Fetal Calf Serum (FCS) containing cells of interest on the lids of 60 mm dishes. Bottom plates of the dishes were filled with sterile Phosphate Buffer Saline (PBS) to avoid desiccation of samples. Lids were then placed on the bottom plates to achieve hanging drop cultures. We utilized this technique for cultivation of ciliated epithelia to study cytotoxicity and differentiation of bone marrow stromal cells. Most importantly the modified culture technique presented here is simple, economical and cost effective in terms of the time taken and the reagents required and are amenable to goal specific modification such as cytotoxicity testing. It is advantageous over the existing system in terms of retention of viability and functionality for longer duration and for providing three dimensional growth micro-environment making it useful for organotypic cultures and in vivo simulation.

Folding of a detachment and fault - Modified detachment folding along a lateral ramp, southwestern Montana, USA

NASA Astrophysics Data System (ADS)

Schmidt, Christopher; Whisner, S. Christopher; Whisner, Jennifer B.

2014-12-01

The inversion of the Middle Proterozoic Belt sedimentary basin during Late Cretaceous thrusting in Montana produced a large eastwardly-convex salient, the southern boundary of which is a 200 km-long oblique to lateral ramp subtended by a detachment between the Belt rocks and Archean basement. A 10 km-long lateral ramp segment exposes the upper levels of the detachment where hanging wall Belt rocks have moved out over the Paleozoic and Mesozoic section. The hanging wall structure consists of a train of high amplitude, faulted, asymmetrical detachment folds. Initial west-east shortening produced layer parallel shortening fabrics and dominantly strike slip faulting followed by symmetrical detachment folding. 'Lock-up' of movement on the detachment surface produced regional simple shear and caused the detachment folds to become asymmetrical and faulted. Folding of the detachment surface after lock-up modified the easternmost detachment folds further into a southeast-verging, overturned fold pair with a ramp-related fault along the base of the stretched mutual limb.

Studying electron transfer through alkanethiol self-assembled monolayers on a hanging mercury drop electrode using potentiometric measurements.

PubMed

Cohen-Atiya, Meirav; Mandler, Daniel

2006-10-14

A new approach based on measuring the change of the open-circuit potential (OCP) of a hanging mercury drop electrode (HMDE), modified with alkanethiols of different chain length conducted in a solution containing a mixture of Ru(NH3)6(2+) and Ru(NH3)6(3+) is used for studying electron transfer across the monolayer. Following the time dependence of the OCP allowed the extraction of the kinetic parameters, such as the charge transfer resistance (R(ct)) and the electron transfer rate constant (k(et)), for different alkanethiol monolayers. An electron tunneling coefficient, beta, of 0.9 A(-1) was calculated for the monolayers on Hg.

Measuring g with a classroom pendulum using changes in the pendulum string length

NASA Astrophysics Data System (ADS)

Oliveira, V.

2016-11-01

This frontline presents a simple apparatus for measuring the acceleration of gravity using a classroom pendulum. Instead of the traditional method where the pendulum period is measured as a function of its length, here the period is measured as a function of changes in the pendulum string length. The major advantage of this method is that students can measure these changes with a greater accuracy than measuring the total pendulum length.

Generation of Homogenous Three-Dimensional Pancreatic Cancer Cell Spheroids Using an Improved Hanging Drop Technique

PubMed Central

Ware, Matthew J.; Colbert, Kevin; Keshishian, Vazrik; Ho, Jason; Corr, Stuart J.; Curley, Steven A.

2016-01-01

In vitro characterization of tumor cell biology or of potential anticancer drugs is usually performed using tumor cell lines cultured as a monolayer. However, it has been previously shown that three-dimensional (3D) organization of the tumor cells is important to provide insights on tumor biology and transport of therapeutics. Several methods to create 3D tumors in vitro have been proposed, with hanging drop technique being the most simple and, thus, most frequently used. However, in many cell lines this method has failed to form the desired 3D tumor structures. The aim of this study was to design and test an easy-to-use and highly reproducible modification of the hanging drop method for tumor sphere formation by adding methylcellulose polymer. Most pancreatic cancer cells do not form cohesive and manageable spheres when the original hanging drop method is used, thus we investigated these cell lines for our modified hanging drop method. The spheroids produced by this improved technique were analyzed by histology, light microscopy, immunohistochemistry, and scanning electron microscopy. Results show that using the proposed simple method; we were able to produce uniform spheroids for all five of the tested human pancreatic cancer cell lines; Panc-1, BxPC-3, Capan-1, MiaPaCa-2, and AsPC-1. We believe that this method can be used as a reliable and reproducible technique to make 3D cancer spheroids for use in tumor biology research and evaluation of therapeutic responses, and for the development of bio-artificial tissues. PMID:26830354

Generation of Homogenous Three-Dimensional Pancreatic Cancer Cell Spheroids Using an Improved Hanging Drop Technique.

PubMed

Ware, Matthew J; Colbert, Kevin; Keshishian, Vazrik; Ho, Jason; Corr, Stuart J; Curley, Steven A; Godin, Biana

2016-04-01

In vitro characterization of tumor cell biology or of potential anticancer drugs is usually performed using tumor cell lines cultured as a monolayer. However, it has been previously shown that three-dimensional (3D) organization of the tumor cells is important to provide insights on tumor biology and transport of therapeutics. Several methods to create 3D tumors in vitro have been proposed, with hanging drop technique being the most simple and, thus, most frequently used. However, in many cell lines this method has failed to form the desired 3D tumor structures. The aim of this study was to design and test an easy-to-use and highly reproducible modification of the hanging drop method for tumor sphere formation by adding methylcellulose polymer. Most pancreatic cancer cells do not form cohesive and manageable spheres when the original hanging drop method is used, thus we investigated these cell lines for our modified hanging drop method. The spheroids produced by this improved technique were analyzed by histology, light microscopy, immunohistochemistry, and scanning electron microscopy. Results show that using the proposed simple method; we were able to produce uniform spheroids for all five of the tested human pancreatic cancer cell lines; Panc-1, BxPC-3, Capan-1, MiaPaCa-2, and AsPC-1. We believe that this method can be used as a reliable and reproducible technique to make 3D cancer spheroids for use in tumor biology research and evaluation of therapeutic responses, and for the development of bio-artificial tissues.

A new class of compact high sensitive tiltmeter based on the UNISA folded pendulum mechanical architecture

NASA Astrophysics Data System (ADS)

Barone, Fabrizio; Giordano, Gerardo

2018-02-01

We present the Extended Folded Pendulum Model (EFPM), a model developed for a quantitative description of the dynamical behavior of a folded pendulum generically oriented in space. This model, based on the Tait-Bryan angular reference system, highlights the relationship between the folded pendulum orientation in the gravitational field and its natural resonance frequency. Tis model validated by tests performed with a monolithic UNISA Folded Pendulum, highlights a new technique of implementation of folded pendulum based tiltmeters.

Experiment with Conical Pendulum

ERIC Educational Resources Information Center

Tongaonkar, S. S.; Khadse, V. R.

2011-01-01

Conical pendulum is similar to simple pendulum with the difference that the bob, instead of moving back and forth, swings around in a horizontal circle. Thus, in a conical pendulum the bob moves at a constant speed in a circle with the string tracing out a cone. This paper describes an experiment with conical pendulum, with determination of g from…

Molar distalization with pendulum appliances in the mixed dentition: effects on the position of unerupted canines and premolars.

PubMed

Kinzinger, Gero S M; Wehrbein, Heinrich; Gross, Ulrich; Diedrich, Peter R

2006-03-01

The pendulum appliance allows for rapid molar distalization without the need for patient compliance. Its efficiency has been confirmed in a number of clinical studies. However, the potential interactions and positional changes between the deciduous molars used for dental anchorage and the erupted and unerupted permanent teeth have yet to be clarified when this appliance is used for molar distalization in the mixed dentition. Twenty-nine patients in the mixed dentition each received a modified pendulum appliance with a distal screw and a preactivated pendulum spring for bilateral distalization of the maxillary molars. The patients were divided into 4 groups based on dentition stages: patient group 1 (PG 1, n = 10) was in the early mixed dentition; patients had resorption of the distal root areas of the deciduous molars being used for dental anchorage, and the unerupted premolars were located at the distal margin of the deciduous molar root region. Based on radiographs taken before placement of the pendulum appliance, patient group 2 (PG 2, n = 10) was diagnosed as having a central location of the unerupted premolars. In the third group (PG 3, n = 4), the first premolars were already erupted and could be integrated into the dental anchorage, but the canines were not yet erupted. In the fourth group (PG 4, n = 5), the first premolars and both canines were fully erupted. Statistical analysis of the measured results showed significant differences in the side effects between PG 1 and PG 2. In patients being treated with pendulum appliances, the anchorage quality of the deciduous molars that were already partially resorbed in the distal root area was comparatively reduced. Consequently, the mesial drift of the deciduous molars and incisors was increased, without impairing the extent and quality of the molar distalization. Anchorage loss in the supporting area had no direct impact on the sagittal position of the unerupted premolars in the early mixed dentition. If permanent teeth have already started to erupt in the supporting area, additional space restrictions should be avoided in patients with critical topography, especially if there is little space for the unerupted canines. At this stage of the mixed dentition, premolar extraction or augmentation of the supporting area with extraoral headgear offers a therapeutic alternative to intraoral distalization appliances with exclusively dental anchorage.

Response of Pendulums to Translational and Rotational Components of Ground Motion

NASA Astrophysics Data System (ADS)

Graizer, V.; Kalkan, E.

2008-12-01

Dynamic response of most seismological instruments and many engineering structures to ground shaking can be represented via response of a pendulum (single-degree-of-freedom oscillator). Pendulum response is usually simplified by considering the input from uni-axial translational motion only. Complete ground motion however, includes not only translational components but also rotations (tilt and torsion). We consider complete equations of motion for three following types of pendulum: (i) conventional mass-on-rod, (ii) mass- on-spring type, and (iii) inverted (astatic), then their response sensitivities to each component of complex ground motion are examined. Inverted pendulums are used in seismology for more than 100 years, for example, classical Wiechert's horizontal seismograph built around 1905 and still used at some seismological observatories, and recent Guralp's horizontal seismometers CMG-40T and CMG-3T. Inverted pendulums also have significant importance for engineering applications where they are often used to simulate the dynamic response of various structural systems. The results of this study show that a horizontal pendulum similar to a modern accelerometer used in strong motion measurements is practically sensitive to translational motion and tilt only, while inverted pendulum is sensitive not only to translational components, but also to angular accelerations and tilt. For better understanding of the inverted pendulum's dynamic behavior under complex ground excitation, relative contribution of each component of motion on response variants is carefully isolated. The responses of pendulums are calculated in time-domain using close-form solution Duhamel's integral with complex input forcing functions. As compared to a common horizontal pendulum, response of an inverted pendulum is sensitive to acceleration of gravity and vertical acceleration when it reaches the level close to 1.0 g. Gravity effect introduces nonlinearity into the differential equation of motion, and results in shift of the frequency response to lower frequencies. The equations of inverted pendulum represent elastic response of pendulums (as material behavior), with nonlinearity created by time and amplitude dependence of equation coefficients. Sensitivity of inverted pendulum to angular acceleration of tilt is proportional to the length of a pendulum, and should be taken into consideration since it can produce significant effect especially for long pendulums, idealizing for instance, bridge piers, bents, elevated water tanks, telecommunication towers, etc.

Swinging into Pendulums with a Background.

ERIC Educational Resources Information Center

Barrow, Lloyd H.; Cook, Julie

1993-01-01

Explains reasons why students have misconceptions concerning pendulum swings. Presents a series of 10 pendulum task cards to provide middle-school students with a solid mental scaffolding upon which to build their knowledge of kinetic energy and pendulums. (PR)

How Short and Light Can a Simple Pendulum Be for Classroom Use?

ERIC Educational Resources Information Center

Oliveira, V.

2014-01-01

We compare the period of oscillation of an ideal simple pendulum with the period of a more "real" pendulum constituted of a rigid sphere and a rigid slender rod. We determine the relative error in the calculation of the local acceleration of gravity if the period of the ideal pendulum is used instead of the period of this real pendulum.

How short and light can a simple pendulum be for classroom use?

NASA Astrophysics Data System (ADS)

Oliveira, V.

2014-07-01

We compare the period of oscillation of an ideal simple pendulum with the period of a more ‘real’ pendulum constituted of a rigid sphere and a rigid slender rod. We determine the relative error in the calculation of the local acceleration of gravity if the period of the ideal pendulum is used instead of the period of this real pendulum.

A contribution to calculation of the mathematical pendulum

NASA Astrophysics Data System (ADS)

Anakhaev, K. N.

2014-11-01

In this work, as a continuation of rigorous solutions of the mathematical pendulum theory, calculated dependences were obtained in elementary functions (with construction of plots) for a complete description of the oscillatory motion of the pendulum with determination of its parameters, such as the oscillation period, deviation angles, time of motion, angular velocity and acceleration, and strains in the pendulum rod (maximum, minimum, zero, and gravitational). The results of calculations according to the proposed dependences closely (≪1%) coincide with the exact tabulated data for individual points. The conditions of ascending at which the angular velocity, angular acceleration, and strains in the pendulum rod reach their limiting values equal to and 5 m 1 g, respectively, are shown. It was revealed that the angular acceleration does not depend on the pendulum oscillation amplitude; the pendulum rod strain equal to the gravitation force of the pendulum R s = m 1 g at the time instant is also independent on the amplitude. The dependences presented in this work can also be invoked for describing oscillations of a physical pendulum, mass on a spring, electric circuit, etc.

Complex pendulum biomass sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoskinson, Reed L.; Kenney, Kevin L.; Perrenoud, Ben C.

A complex pendulum system biomass sensor having a plurality of pendulums. The plurality of pendulums allow the system to detect a biomass height and density. Each pendulum has an angular deflection sensor and a deflector at a unique height. The pendulums are passed through the biomass and readings from the angular deflection sensors are fed into a control system. The control system determines whether adjustment of machine settings is appropriate and either displays an output to the operator, or adjusts automatically adjusts the machine settings, such as the speed, at which the pendulums are passed through the biomass. In anmore » alternate embodiment, an entanglement sensor is also passed through the biomass to determine the amount of biomass entanglement. This measure of entanglement is also fed into the control system.« less

The influences of load mass changing on inverted pendulum stability based on simulation study

NASA Astrophysics Data System (ADS)

Pangaribuan, Timbang; Nasruddin, M. N.; Marlianto, Eddy; Sigiro, Mula

2017-09-01

An inverted pendulum has nonlinear dynamic, so it is not easy to do in analysis to see its behavior. From many observations which have been made, there are two things that need to be added on the perfection of inverted pendulum. Firstly, when the pendulum has a large mass, and the second when the pendulum is given a load mass much larger than mass of the inverted pendulum. There are some question, first, how big the load mass can be given so that the movement of the inverted pendulum stay stable is. Second, how weight the changes and moves of load mass which can be given. For all the changes, it hopes the inverted pendulum is stay stable. Finally, the final result is still expected to be as stable, it must need conclude what kind of controller is capable of carrying such a mass burden, and how large the mass load limit can be given.

Imprinted polymer-modified hanging mercury drop electrode for differential pulse cathodic stripping voltammetric analysis of creatine.

PubMed

Lakshmi, Dhana; Sharma, Piyush S; Prasad, Bhim B

2007-06-15

The molecularly imprinted polymer [poly(p-aminobenzoicacid-co-1,2-dichloroethane)] film casting was made on the surface of a hanging mercury drop electrode by drop-coating method for the selective and sensitive evaluation of creatine in water, blood serum and pharmaceutical samples. The molecular recognition of creatine by the imprinted polymer was found to be specific via non-covalent (electrostatic) imprinting. The creatine binding could easily be detected by differential pulse, cathodic stripping voltammetric signal at optimised operational conditions: accumulation potential -0.01 V (versus Ag/AgCl), polymer deposition time 15s, template accumulation time 60s, pH 7.1 (supporting electrolyte< or =5 x 10(-4)M NaOH), scan rate 10 mV s(-1), pulse amplitude 25 mV. The modified sensor in the present study was found to be highly reproducible and selective with detection limit 0.11 ng mL(-1) of creatine. Cross-reactivity studies revealed no response to the addition of urea, creatinine and phenylalanine; however, some insignificant magnitude of current was observed for tryptophan and histidine in the test samples.

Vibration analysis of rotor blades with pendulum absorbers

NASA Technical Reports Server (NTRS)

Murthy, V. R.; Hammond, C. E.

1979-01-01

A comprehensive vibration analysis of rotor blades with spherical pendulum absorbers is presented. Linearized equations of motion for small oscillations about the steady-state deflection of a spherical pendulum on elastic rotor blades undergoing coupled flapwise bending, chordwise bending, and torsional vibrations are obtained. A transmission matrix formulation is given to determine the natural vibrational characteristics of rotor blades with spherical or simple flapping pendulum absorbers. The natural frequencies and mode shapes of a hingeless rotor blade with a spherical pendulum are computed.

Lyapunov stability analysis for the generalized Kapitza pendulum

NASA Astrophysics Data System (ADS)

Druzhinina, O. V.; Sevastianov, L. A.; Vasilyev, S. A.; Vasilyeva, D. G.

2017-12-01

In this work generalization of Kapitza pendulum whose suspension point moves in the vertical and horizontal planes is made. Lyapunov stability analysis of the motion for this pendulum subjected to excitation of periodic driving forces and stochastic driving forces that act in the vertical and horizontal planes has been studied. The numerical study of the random motion for generalized Kapitza pendulum under stochastic driving forces has made. It is shown the existence of stable quasi-periodic motion for this pendulum.

Stabilization and tracking control of X-Z inverted pendulum with sliding-mode control.

PubMed

Wang, Jia-Jun

2012-11-01

X-Z inverted pendulum is a new kind of inverted pendulum which can move with the combination of the vertical and horizontal forces. Through a new transformation, the X-Z inverted pendulum is decomposed into three simple models. Based on the simple models, sliding-mode control is applied to stabilization and tracking control of the inverted pendulum. The performance of the sliding mode control is compared with that of the PID control. Simulation results show that the design scheme of sliding-mode control is effective for the stabilization and tracking control of the X-Z inverted pendulum. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

A three-dimensional finite element analysis of molar distalization with a palatal plate, pendulum, and headgear according to molar eruption stage.

PubMed

Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Kook, Yoon-Ah; Mo, Sung-Seo

2016-09-01

This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization.

Flexor and extensor muscle tone evaluated using the quantitative pendulum test in stroke and parkinsonian patients.

PubMed

Huang, Han-Wei; Ju, Ming-Shaung; Lin, Chou-Ching K

2016-05-01

The aim of this study was to evaluate the flexor and extensor muscle tone of the upper limbs in patients with spasticity or rigidity and to investigate the difference in hypertonia between spasticity and rigidity. The two experimental groups consisted of stroke patients and parkinsonian patients. The control group consisted of age and sex-matched normal subjects. Quantitative upper limb pendulum tests starting from both flexed and extended joint positions were conducted. System identification with a simple linear model was performed and model parameters were derived. The differences between the three groups and two starting positions were investigated by these model parameters and tested by two-way analysis of variance. In total, 57 subjects were recruited, including 22 controls, 14 stroke patients and 21 parkinsonian patients. While stiffness coefficient showed no difference among groups, the number of swings, relaxation index and damping coefficient showed changes suggesting significant hypertonia in the two patient groups. There was no difference between these two patient groups. The test starting from the extended position constantly manifested higher muscle tone in all three groups. In conclusion, the hypertonia of parkinsonian and stroke patients could not be differentiated by the modified pendulum test; the elbow extensors showed a higher muscle tone in both control and patient groups; and hypertonia of both parkinsonian and stroke patients is velocity dependent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thrust Measurements in Ballistic Pendulum Ablative Laser Propulsion Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brazolin, H.; Rodrigues, N. A. S.; Minucci, M. A. S.

This paper describes a setup for thrust measurement in ablative laser propulsion experiments, based on a simple ballistic pendulum associated to an imaging system, which is being assembled at IEAv. A light aluminium pendulum holding samples is placed inside a 100 liters vacuum chamber with two optical windows: the first (in ZnSe) for the laser beam and the second (in fused quartz) for the pendulum visualization. A TEA-CO{sub 2} laser beam is focused to the samples providing ablation and transferring linear moment to the pendulum as a whole. A CCD video camera captures the oscillatory movement of the pendulum andmore » the its trajectory is obtained by image processing. By fitting the trajectory of the pendulum to a dumped sinusoidal curve is possible to obtain the amplitude of the movement which is directly related to the momentum transfered to the sample.« less

Towards the miniaturization of monolithic folded pendulums: a new approach to the implementation of small and light sensors for ground, space, and marine applications

NASA Astrophysics Data System (ADS)

Barone, F.; Giordano, G.

2018-03-01

The UNISA Folded Pendulum technological platform is very promising for the implementation of high sensitive, large band miniaturized mechanical seismometers and accelerometers in different materials. In fact, the symmetry of its mechanical architecture allows to take full advantage of one of the most relevant properties of the folded pendulum, that is the scalability. This property is very useful for the design of folded pendulums of small size and weight, provided with a suitable combination of physical and geometrical parameters. Using a lagrangian simplified model of folded pendulum, we present and discuss this idea, showing different possible approaches that may lead to the miniaturization of a folded pendulum. Finally we present a first prototype of miniaturized folded pendulum, discussing its characteristics and limitations, in connection with scientific ground, marine and space applications.

Pendulums in the Physics Education Literature: A Bibliography

ERIC Educational Resources Information Center

Gauld, Colin

2004-01-01

Articles about the pendulum in four journals devoted to the teaching of physics and one general science teaching journal (along with other miscellaneous articles from other journals) are listed in three broad categories--types of pendulums, the contexts in which these pendulums are used in physics teaching at secondary or tertiary levels and a…

Introduction to the Treatment of Non-Linear Effects Using a Gravitational Pendulum

ERIC Educational Resources Information Center

Weltner, Klaus; Esperidiao, Antonio Sergio C.; Miranda, Paulo

2004-01-01

We show that the treatment of pendulum movement, other than the linear approximation,may be an instructive experimentally based introduction to the physics of non-linear effects. Firstly the natural frequency of a gravitational pendulum is measured as function of its amplitude. Secondly forced oscillations of a gravitational pendulum are…

49 CFR 572.193 - Neck assembly.

Code of Federal Regulations, 2014 CFR

2014-10-01

... or V2-B in appendix A to this subpart, to the 49 CFR Part 572 pendulum test fixture (Figure 22, 49... motion of the pendulum longitudinal centerline; (3) Release the pendulum from a height sufficient to achieve a velocity of 5.57 ±0.06 m/s measured at the center of the pendulum accelerometer, as shown in 49...

49 CFR 572.73 - Neck assembly and test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... rotate, while translating in the direction of the pendulum preimpact flight, in reference to the pendulum... displacement at time “T” is defined as the straight line distance between the position relative to the pendulum arm of the head's center of gravity at time “zero;” and the position relative to the pendulum arm of...

49 CFR 572.193 - Neck assembly.

Code of Federal Regulations, 2012 CFR

2012-10-01

... or V2-B in appendix A to this subpart, to the 49 CFR Part 572 pendulum test fixture (Figure 22, 49... motion of the pendulum longitudinal centerline; (3) Release the pendulum from a height sufficient to achieve a velocity of 5.57 ±0.06 m/s measured at the center of the pendulum accelerometer, as shown in 49...

49 CFR 572.73 - Neck assembly and test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... rotate, while translating in the direction of the pendulum preimpact flight, in reference to the pendulum... displacement at time “T” is defined as the straight line distance between the position relative to the pendulum arm of the head's center of gravity at time “zero;” and the position relative to the pendulum arm of...

A Simple Method to Measure the Trajectory of a Spherical Pendulum

ERIC Educational Resources Information Center

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…

49 CFR 572.193 - Neck assembly.

Code of Federal Regulations, 2013 CFR

2013-10-01

... or V2-B in appendix A to this subpart, to the 49 CFR Part 572 pendulum test fixture (Figure 22, 49... motion of the pendulum longitudinal centerline; (3) Release the pendulum from a height sufficient to achieve a velocity of 5.57 ±0.06 m/s measured at the center of the pendulum accelerometer, as shown in 49...

49 CFR 572.193 - Neck assembly.

Code of Federal Regulations, 2011 CFR

2011-10-01

... or V2-B in appendix A to this subpart, to the 49 CFR Part 572 pendulum test fixture (Figure 22, 49... of motion of the pendulum longitudinal centerline; (3) Release the pendulum from a height sufficient to achieve a velocity of 5.57 ± 0.06 m/s measured at the center of the pendulum accelerometer, as...

49 CFR 572.73 - Neck assembly and test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... rotate, while translating in the direction of the pendulum preimpact flight, in reference to the pendulum... displacement at time “T” is defined as the straight line distance between the position relative to the pendulum arm of the head's center of gravity at time “zero;” and the position relative to the pendulum arm of...

Turning Points of the Spherical Pendulum and the Golden Ratio

ERIC Educational Resources Information Center

Essen, Hanno; Apazidis, Nicholas

2009-01-01

We study the turning point problem of a spherical pendulum. The special cases of the simple pendulum and the conical pendulum are noted. For simple initial conditions the solution to this problem involves the golden ratio, also called the golden section, or the golden number. This number often appears in mathematics where you least expect it. To…

49 CFR 572.73 - Neck assembly and test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... rotate, while translating in the direction of the pendulum preimpact flight, in reference to the pendulum... displacement at time “T” is defined as the straight line distance between the position relative to the pendulum arm of the head's center of gravity at time “zero;” and the position relative to the pendulum arm of...

49 CFR 572.193 - Neck assembly.

Code of Federal Regulations, 2010 CFR

2010-10-01

... or V2-B in appendix A to this subpart, to the 49 CFR Part 572 pendulum test fixture (Figure 22, 49... of motion of the pendulum longitudinal centerline; (3) Release the pendulum from a height sufficient to achieve a velocity of 5.57 ± 0.06 m/s measured at the center of the pendulum accelerometer, as...

49 CFR 572.73 - Neck assembly and test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... rotate, while translating in the direction of the pendulum preimpact flight, in reference to the pendulum... displacement at time “T” is defined as the straight line distance between the position relative to the pendulum arm of the head's center of gravity at time “zero;” and the position relative to the pendulum arm of...

Inverting the Pendulum Using Fuzzy Control (Center Director's Discretionary Fund (Project 93-02)

NASA Technical Reports Server (NTRS)

Kissel, R. R.; Sutherland, W. T.

1997-01-01

A single pendulum was simulated in software and then built on a rotary base. A fuzzy controller was used to show its advantages as a nonlinear controller since bringing the pendulum inverted is extremely nonlinear. The controller was implemented in a Motorola 6811 microcontroller. A double pendulum was simulated and fuzzy control was used to hold it in a vertical position. The double pendulum was not built into hardware for lack of time. This project was for training and to show advantages of fuzzy control.

Intelligent clutch control with incremental encoder to improve wear issues of an intercept pendulum in real time

NASA Astrophysics Data System (ADS)

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.

Roles of Abductive Reasoning and Prior Belief in Children's Generation of Hypotheses about Pendulum Motion

ERIC Educational Resources Information Center

Kwon, Yong-Ju; Jeong, Jin-Su; Park, Yun-Bok

2006-01-01

The purpose of the present study was to test the hypothesis that student's abductive reasoning skills play an important role in the generation of hypotheses on pendulum motion tasks. To test the hypothesis, a hypothesis-generating test on pendulum motion, and a prior-belief test about pendulum motion were developed and administered to a sample of…

Foot trajectory approximation using the pendulum model of walking.

PubMed

Fang, Juan; Vuckovic, Aleksandra; Galen, Sujay; Conway, Bernard A; Hunt, Kenneth J

2014-01-01

Generating a natural foot trajectory is an important objective in robotic systems for rehabilitation of walking. Human walking has pendular properties, so the pendulum model of walking has been used in bipedal robots which produce rhythmic gait patterns. Whether natural foot trajectories can be produced by the pendulum model needs to be addressed as a first step towards applying the pendulum concept in gait orthosis design. This study investigated circle approximation of the foot trajectories, with focus on the geometry of the pendulum model of walking. Three able-bodied subjects walked overground at various speeds, and foot trajectories relative to the hip were analysed. Four circle approximation approaches were developed, and best-fit circle algorithms were derived to fit the trajectories of the ankle, heel and toe. The study confirmed that the ankle and heel trajectories during stance and the toe trajectory in both the stance and the swing phases during walking at various speeds could be well modelled by a rigid pendulum. All the pendulum models were centred around the hip with pendular lengths approximately equal to the segment distances from the hip. This observation provides a new approach for using the pendulum model of walking in gait orthosis design.

Radial forcing and Edgar Allan Poe's lengthening pendulum

NASA Astrophysics Data System (ADS)

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.

A Study for the Restoration of Hong Dae-Yong Honsangui - Focusing on the structure and operating mechanism

NASA Astrophysics Data System (ADS)

Lee, Yong Sam; Kim, Sang Hyuk; Park, Je Hoon

2013-09-01

Honsangui (celestial globe) which is a water-hammering method astronomical clock is recorded in "Juhaesuyong" which is Volume VI of supplement from "Damheonseo", written by Hong Dae-Yong (1731~1783). We made out the conceptual design of Hong Dae-Yong's Honsangui through the study on its structure and working mechanism. Honsangui consist of three rings and two layers, the structure of rings which correspond to outer layer is similar to his own Tongcheonui (armillary sphere) which is a kind of armillary sphere. Honsang sphere which correspond to inner layer depicts constellations and milky way and two beads hang on it as Sun and Moon respectively for realize the celestial motion. Tongcheonui is operated by the pendulum power but Honsangui is operated by water-hammering method mechanism. This Honsangui's working mechanism is the traditional way of Joseon and it was simplified the working mechanism of Shui y'n i hsiang t'ai which is a representative astronomical clock of China. This record of Honsangui is the only historical record about the water-hammering method working mechanism of Joseon Era and it provide the study of water-hammering method mechanism with a vital clue.

Desktop chaotic systems: Intuition and visualization

NASA Technical Reports Server (NTRS)

Bright, Michelle M.; Melcher, Kevin J.; Qammar, Helen K.; Hartley, Tom T.

1993-01-01

This paper presents a dynamic study of the Wildwood Pendulum, a commercially available desktop system which exhibits a strange attractor. The purpose of studying this chaotic pendulum is twofold: to gain insight in the paradigmatic approach of modeling, simulating, and determining chaos in nonlinear systems; and to provide a desktop model of chaos as a visual tool. For this study, the nonlinear behavior of this chaotic pendulum is modeled, a computer simulation is performed, and an experimental performance is measured. An assessment of the pendulum in the phase plane shows the strange attractor. Through the use of a box-assisted correlation dimension methodology, the attractor dimension is determined for both the model and the experimental pendulum systems. Correlation dimension results indicate that the pendulum and the model are chaotic and their fractal dimensions are similar.

The Pendulum as a Vehicle for Transitioning from Classical to Quantum Physics: History, Quantum Concepts, and Educational Challenges

ERIC Educational Resources Information Center

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…

Segmented Hoop as a Physical Pendulum

ERIC Educational Resources Information Center

Layton, William; Rodriguez, Nuria

2013-01-01

An interesting demonstration with a surprising result is to suspend a hoop from a point near its edge and set it swinging in a vertical plane as a pendulum. If a simple pendulum of length equal to the diameter of the hoop is set oscillating at the same time, the two will have nearly the same period. However, the real surprise is if the pendulum is…

A Novel Real-Time Data Acquisition Using an Excel Spreadsheet in Pendulum Experiment Tool with Light-Based Timer

ERIC Educational Resources Information Center

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…

Dynamic stabilization of an optomechanical oscillator

DTIC Science & Technology

2014-10-20

respectively. The proper frequency of the pendulum is ω0 = √ g/, where g is the gravitational acceleration and is the length of the pendulum . The...controlled experiments. In this paper we discuss one such situation, the dynamic stabilization of a mechanical system such as an inverted pendulum . The...quantumoptomechanics, macroscopic quantum system, dynamic stabilization, Kapitza pendulum REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S

Ask the pendulum: personality predictors of ideomotor performance.

PubMed

Olson, Jay A; Jeyanesan, Ewalina; Raz, Amir

2017-01-01

For centuries, people have asked questions to hand-held pendulums and interpreted their movements as responses from the divine. These movements occur due to the ideomotor effect, wherein priming or thinking of a motion causes muscle movements that end up swinging the pendulum. By associating particular swinging movements with "yes" and "no" responses, we investigated whether pendulums can aid decision-making and which personality traits correlate with this performance. Participants ( N = 80 ) completed a visual detection task in which they searched for a target letter among rapidly presented characters. In the verbal condition, participants stated whether they saw the target in each trial. In the pendulum condition, participants instead mentally "asked" a hand-held pendulum whether the target was present; particular motions signified "yes" and "no". We measured the accuracy of their responses as well as their sensitivity and bias using signal detection theory. We also assessed four personality measures: locus of control (feelings of control over one's life), transliminality (sensitivity to subtle stimuli), need for cognition (preference for analytical thinking), and faith in intuition (preference for intuitive thinking). Overall, locus of control predicted verbal performance and transliminality predicted pendulum performance. Accuracy was low in both conditions (verbal: 57%, pendulum: 53%), but bias was higher in the verbal condition ( d = 1.10 ). We confirmed this bias difference in a second study ( d = 0.47 , N = 40 ). Our results suggest that people have different decision strategies when using a pendulum compared to conscious guessing. These findings may help explain why some people can answer questions more accurately with pendulums and Ouija boards. More broadly, identifying the differences between ideomotor and verbal responses could lead to practical ways to improve decision-making.

Ask the pendulum: personality predictors of ideomotor performance

PubMed Central

Olson, Jay A; Jeyanesan, Ewalina; Raz, Amir

2017-01-01

Abstract For centuries, people have asked questions to hand-held pendulums and interpreted their movements as responses from the divine. These movements occur due to the ideomotor effect, wherein priming or thinking of a motion causes muscle movements that end up swinging the pendulum. By associating particular swinging movements with “yes” and “no” responses, we investigated whether pendulums can aid decision-making and which personality traits correlate with this performance. Participants (N=80) completed a visual detection task in which they searched for a target letter among rapidly presented characters. In the verbal condition, participants stated whether they saw the target in each trial. In the pendulum condition, participants instead mentally “asked” a hand-held pendulum whether the target was present; particular motions signified “yes” and “no”. We measured the accuracy of their responses as well as their sensitivity and bias using signal detection theory. We also assessed four personality measures: locus of control (feelings of control over one’s life), transliminality (sensitivity to subtle stimuli), need for cognition (preference for analytical thinking), and faith in intuition (preference for intuitive thinking). Overall, locus of control predicted verbal performance and transliminality predicted pendulum performance. Accuracy was low in both conditions (verbal: 57%, pendulum: 53%), but bias was higher in the verbal condition (d=1.10). We confirmed this bias difference in a second study (d=0.47, N=40). Our results suggest that people have different decision strategies when using a pendulum compared to conscious guessing. These findings may help explain why some people can answer questions more accurately with pendulums and Ouija boards. More broadly, identifying the differences between ideomotor and verbal responses could lead to practical ways to improve decision-making. PMID:29877514

Optimal formation of genetically modified and functional pancreatic islet spheroids by using hanging-drop strategy.

PubMed

Kim, H J; Alam, Z; Hwang, J W; Hwang, Y H; Kim, M J; Yoon, S; Byun, Y; Lee, D Y

2013-03-01

Rejection and hypoxia are important factors causing islet loss at an early stage after pancreatic islet transplantation. Recently, islets have been dissociated into single cells for reaggregation into so-called islet spheroids. Herein, we used a hanging-drop strategy to form islet spheroids to achieve functional equivalence to intact islets. To obtain single islet cells, we dissociated islets with trypsin-EDTA digestion for 10 minutes. To obtain spheroids, we dropped various numbers of single cells (125, 250, or 500 cells/30 μL drop) onto a Petri dish, that was inverted for incubation in humidified air containing 5% CO(2) at 37 °C for 7 days. The aggregated spheroids in the droplets were harvested for further culture. The size of the aggregated islet spheroids depended on the number of single cells (125-500 cells/30 μL droplet). Their morphology was similar to that of intact islets without any cellular damage. When treated with various concentrations of glucose to evaluate responsiveness, their glucose-mediated stimulation index value was similar to that of intact islets, an observation that was attributed to strong cell-to-cell interactions in islet spheroids. However, islet spheroids aggregated in general culture dishes showed abnormal glucose responsiveness owing to weak cell-to-cell interactions. Cell-to-cell interactions in islet spheroids were confirmed with an anti-connexin-36 monoclonal antibody. Finally, nonviral poly(ethylene imine)-mediated interleukin-10 cytokine gene delivered beforehand into dissociated single cells before formation of islet spheroids increased the gene transfection efficacy and interleukin-10 secretion from islet spheroids >4-fold compared with intact islets. These results demonstrated the potential application of genetically modified, functional islet spheroids with of controlled size and morphology using an hanging-drop technique. Copyright © 2013 Elsevier Inc. All rights reserved.

A biomechanical model of the craniomandibular complex and cervical spine based on the inverted pendulum.

PubMed

Gillies, G T; Broaddus, W C; Stenger, J M; Taylor, A G

1998-01-01

The head and neck constitute an inverted pendulum that is stabilized during consciousness by neuromuscular restoring forces. An analysis of the dynamics of this inverted pendulum suggests that the mechanics of the mandible and temporomandibular joint might couple into those of the pendulum's stabilization process. In this article, physical principles of the inverted pendulum model as these apply to the head and neck are explored, and the authors describe implications of mandibular mechanics for the forces acting on the head and neck at equilibrium. This novel application of the inverted pendulum model predicts that alteration or pathology of temporomandibular mechanics would lead to perturbations of the normal forces acting in the head and neck. Under certain circumstances, these perturbations could be expected to contribute to symptoms and result in additional or accelerated degenerative effects.

Charge management for gravitational-wave observatories using UV LEDs

NASA Astrophysics Data System (ADS)

Pollack, S. E.; Turner, M. D.; Schlamminger, S.; Hagedorn, C. A.; Gundlach, J. H.

2010-01-01

Accumulation of electrical charge on the end mirrors of gravitational-wave observatories can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational-wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable plate brought near a plate pendulum suspended from a nonconducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging of the pendulum with equivalent charging rates of ˜105e/s, as well as spectral measurements of the pendulum charge resulting in a white noise level equivalent to 3×105e/Hz.

Energy behavior of an electromechanical system with internal impacts and uncertainties

NASA Astrophysics Data System (ADS)

Lima, Roberta; Sampaio, Rubens

2016-07-01

This paper analyzes the maximal energy stored in an elastic barrier due to the impacts of a pendulum fitted within a vibro-impact electromechanical system considering the existence of epistemic uncertainties in the system parameters. The vibro-impact electromechanical system is composed of two subsystems. The first subsystem is the electromechanical system composed by a motor, cart and pendulum, and the second is an elastic barrier. The first will be called striker system. The pendulum is fitted within the cart. Its suspension point is fixed in the cart, so that it may exist a relative motion between cart and pendulum. The influence of the DC motor in the dynamic behavior of the pendulum is considered. The coupling between the motor and the cart is made by a scotch yoke mechanism, so that the motor rotational motion is transformed in horizontal cart motion over a rail. The pendulum is modeled as a mathematical pendulum (bar without mass and particle of mass mp at the end). A flexible barrier, placed inside the cart, constrains the pendulum motion. Due to the relative motion between the cart and the pendulum, impacts may occur between these two elements. The objective of the paper is to analyze the energy stored in the barrier due to impacts as a function of some parameters of the electromechanical system from a deterministic and from a stochastic viewpoint. The system is designed as an aid in drilling. The impacts damage or fracture the rock and facilitate the conventional drilling.

Equivalence Reliability among the FITNESSGRAM[R] Upper-Body Tests of Muscular Strength and Endurance

ERIC Educational Resources Information Center

Sherman, Todd; Barfield, J. P.

2006-01-01

This study was designed to investigate the equivalence reliability between the suggested FITNESSGRAM[R] muscular strength and endurance test, the 90[degrees] push-up (PSU), and alternate FITNESSGRAM[R] tests of upper-body strength and endurance (i.e., modified pull-up [MPU], flexed-arm hang [FAH], and pull-up [PU]). Children (N = 383) in Grades 3…

Response of pendulums to complex input ground motion

USGS Publications Warehouse

Graizer, V.; Kalkan, E.

2008-01-01

Dynamic response of most seismological instruments and many engineering structures to ground shaking can be represented via response of a pendulum (single-degree-of-freedom oscillator). In most studies, pendulum response is simplified by considering the input from uni-axial translational motion alone. Complete ground motion however, includes not only translational components but also rotations (tilt and torsion). In this paper, complete equations of motion for three following types of pendulum are described: (i) conventional (mass-on-rod), (ii) mass-on-spring type, and (iii) inverted (astatic), then their response sensitivities to each component of complex ground motion are examined. The results of this study show that a horizontal pendulum similar to an accelerometer used in strong motion measurements is practically sensitive to translational motion and tilt only, while inverted pendulum commonly utilized to idealize multi-degree-of-freedom systems is sensitive not only to translational components, but also to angular accelerations and tilt. For better understanding of the inverted pendulum's dynamic behavior under complex ground excitation, relative contribution of each component of motion on response variants is carefully isolated. The systematically applied loading protocols indicate that vertical component of motion may create time-dependent variations on pendulum's oscillation period; yet most dramatic impact on response is produced by the tilting (rocking) component. ?? 2007 Elsevier Ltd. All rights reserved.

Assessment of energy harvesting and vibration mitigation of a pendulum dynamic absorber

NASA Astrophysics Data System (ADS)

Kecik, Krzysztof

2018-06-01

The paper presents a novel system for simultaneous energy harvesting and vibration mitigation. The system consists of two main parts: an autoparametric pendulum vibration absorber and an energy harvester device. The recovered energy is from oscillation of a levitating magnet in a coil. The energy harvesting system is mounted in a pendulum structure. The system allows energy recovery from a semi-trivial solution (pendulum in rest) or/and swinging of a pendulum. The influence of harvester parameters on the system response and energy harvesting in a parametric resonance is studied in detail. The harvester device does not decrease vibration reduction effectiveness.

Measure synchronization in a Huygens's non-dissipative two-pendulum clocks system

NASA Astrophysics Data System (ADS)

Tian, Jing; Chen, ZiChen; Qiu, HaiBo; Xi, XiaoQiang

2018-01-01

In this paper, we characterize measure synchronization (MS) in a four-degrees-of-freedom Huygens's two-pendulum clocks system. The two-pendulum clocks are connected by a massless spring with stiffness constant k. We find that with the stiffness constant k increasing, the coupled pendulums system achieves MS above a threshold value of k c . The energy characteristics of measure synchronization have been discussed, it is found that averaged energy of each pendulum system provide us an easy way to characterize MS transition. Furthermore, we discuss the dependence of the critical value for MS transition on initial conditions and the characteristic parameters of the system.

Shoulder Injuries and Disorders - Multiple Languages

MedlinePlus

... Af-Soomaali (Somali) Bilingual PDF Health Information Translations Pendulum Exercises for Shoulder - Af-Soomaali (Somali) Bilingual PDF ... Exercises - español (Spanish) Bilingual PDF Health Information Translations Pendulum Exercises for Shoulder - English PDF Pendulum Exercises for ...

Plume Characterization of Busek 600W Hall Thruster

DTIC Science & Technology

2012-03-09

probe was used to examine the thruster plume current density while the ion species fractions were determined by the ExB probe. The inverted pendulum ...25 A. Inverted Pendulum ...Diagnostic Equipment .....................................................................................45 A. Inverted Pendulum

Precessional Periods of Long and Short Foucault Pendulums

ERIC Educational Resources Information Center

Soga, Michitoshi

1978-01-01

Derives the precessional period of a Foucault pendulum without using small oscillation amplitudes. Shows that if the path of the pendulum passes through the origin, the periods for differing amplitudes are essentially the same. (GA)

A three-dimensional finite element analysis of molar distalization with a palatal plate, pendulum, and headgear according to molar eruption stage

PubMed Central

Kang, Ju-Man; Park, Jae Hyun; Bayome, Mohamed; Oh, Moonbee; Park, Chong Ook; Mo, Sung-Seo

2016-01-01

Objective This study aimed to (1) evaluate the effects of maxillary second and third molar eruption status on the distalization of first molars with a modified palatal anchorage plate (MPAP), and (2) compare the results to the outcomes of the use of a pendulum and that of a headgear using three-dimensional finite element analysis. Methods Three eruption stages were established: an erupting second molar at the cervical one-third of the first molar root (Stage 1), a fully erupted second molar (Stage 2), and an erupting third molar at the cervical one-third of the second molar root (Stage 3). Retraction forces were applied via three anchorage appliance models: an MPAP with bracket and archwire, a bone-anchored pendulum appliance, and cervical-pull headgear. Results An MPAP showed greater root movement of the first molar than crown movement, and this was more noticeable in Stages 2 and 3. With the other devices, the first molar showed distal tipping. Transversely, the first molar had mesial-out rotation with headgear and mesial-in rotation with the other devices. Vertically, the first molar was intruded with an MPAP, and extruded with the other appliances. Conclusions The second molar eruption stage had an effect on molar distalization, but the third molar follicle had no effect. The application of an MPAP may be an effective treatment option for maxillary molar distalization. PMID:27668192

A Fiber Optic Probe for Monitoring Protein Aggregation, Nucleation, and Crystallization

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Suh, Kwang I.; Arabshahi, Alireza; Wilson, William W.; Bray, Terry L.; DeLucas, Lawrence J.

1996-01-01

Protein crystals are experimentally grown in hanging drops in microgravity experiments on-board the Space Shuttle orbiter. The technique of dynamic light scattering (DLS) can be used to monitor crystal growth process in hanging droplets (approx. 30 (L)) in microgravity experiments, but elaborate instrumentation and optical alignment problems have made in-situ applications difficult. In this paper we demonstrate that such experiments are now feasible. We apply a newly developed fiber optic probe to various earth and space (micro- gravity) bound protein crystallization system configurations to test its capability. These include conventional batch (cuvette or capillary) systems, hanging drop method in a six-pack hanging drop vapor diffusion apparatus (HDVDA), a modified HDVDA for temperature- induced nucleation and aggregation studies, and a newly envisioned dynamically controlled vapor diffusion system (DCVDS) configuration. Our compact system exploits the principles of DLS and offers a fast (within a few seconds) means of quantitatively and non-invasively monitoring the various growth stages of protein crystallization. In addition to DLS capability, the probe can also be used for performing single-angle static light scattering measurements. It utilizes extremely low levels of laser power (approx. few (W)) without a need of having any optical alignment and vibration isolation. The compact probe is also equipped with a miniaturized microscope for visualization of macroscopic protein crystals. This new optical diagnostic system opens up enormous opportunity for exploring new ways to grow good quality crystals suitable for x-ray crystallographic analysis and may help develop a concrete scientific basis for understanding the process of crystallization.

[Study on molecular recognition technology in active constituents extracted and isolated from Aconitum pendulum].

PubMed

Ma, Xue-Qin; Li, Guo-Shan; Fu, Xue-Yan; Ma, Jing-Zu

2011-03-01

To investigate CD molecular recognition technology applied in active constituents extracted and isolated from traditional Chinese medicine--Aconitum pendulum. The inclusion constant and form probability of the inclusion complex of Aconitum pendulum with p-CD was calculated by UV spectra method. The active constituents of Aconitum pendulum were extracted and isolated by molecular recognition technology. The inclusion complex was identified by UV. The chemical constituents of Aconitum pendulum and inclusion complex was determined by HPLC. The analgesic effects of inclusion complex was investigated by experiment of intraperitoneal injection of acetic acid in rats. The inclusion complex was identified and confirmed by UV spectra method, the chemical components of inclusion complex were simple, and the content of active constituents increased significantly, the analgesic effects of inclusion complex was well. The molecular recognition technology can be used for extracting and isolating active constituents of Aconitum pendulum, and the effects are obvious.

Charge management for gravitational-wave observatories using UV LEDs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pollack, S. E.; Turner, M. D.; Schlamminger, S.

Accumulation of electrical charge on the end mirrors of gravitational-wave observatories can become a source of noise limiting the sensitivity of such detectors through electronic couplings to nearby surfaces. Torsion balances provide an ideal means for testing gravitational-wave technologies due to their high sensitivity to small forces. Our torsion pendulum apparatus consists of a movable plate brought near a plate pendulum suspended from a nonconducting quartz fiber. A UV LED located near the pendulum photoejects electrons from the surface, and a UV LED driven electron gun directs photoelectrons towards the pendulum surface. We have demonstrated both charging and discharging ofmore » the pendulum with equivalent charging rates of {approx}10{sup 5}e/s, as well as spectral measurements of the pendulum charge resulting in a white noise level equivalent to 3x10{sup 5}e/{radical}(Hz).« less

The Reproduction of Scientific Understanding about Pendulum Motion in the Public

NASA Astrophysics Data System (ADS)

Manabu, Sumida

This paper describes life-span development of understanding about pendulum motion and effects of school science. The subjects were 2,766 people ranging from kindergartners up to 88 years senior citizens. The conflict and consensus between children and their parent's understanding of pendulum motion were also analyzed. The kindergartner's understanding, mostly non-scientific, made a marked developmental change to another type of non-scientific understanding by the time they reach G 4. Parents with scientific understanding do not presumably nurture scientifically minded children,even though about half of them can apply scientific conceptions that shorter pendulums swing faster, and the amplitude and speed of pendulum motion do not depend on its weight. There seems to be another type of developmental change from scientific understanding to non-scientific understanding around their fifties. Itis suggested that the scientific understanding in the public about pendulum motion become predominant due to the educational intervention through school science.

Design and Experimental Implementation of Optimal Spacecraft Antenna Slews

DTIC Science & Technology

2013-12-01

LINK PENDULUM MODEL ............................................................58  C.  AZIMUTH-ELEVATION SYSTEM...BOUNDARY VALUE PROBLEM ......................77  B.  DOUBLE PENDULUM EXAMPLE............................................................82  C.  SOLVING THE...Figure 15.  Two-link Pendulum .........................................................................................58  Figure 16.  Double

Motion of a pendulum with damping and vibrating axis of suspension at unconventional values of parameters

NASA Astrophysics Data System (ADS)

Demidov, Ivan; Sorokin, Vladislav

2018-05-01

Motion of a pendulum with damping and vibrating axis of suspension is considered at unconventional values of parameters. Case when the frequency of external loading and the natural frequency of the pendulum in the absence of this loading are of the same order is studied. Vibration intensity is assumed to be relatively low. In this case, the corresponding equation of the pendulum's motions doesn't involve an explicit small parameter. To solve the equation a new modification of the method of direct separation of motions is used. As the result, stability conditions of the pendulum inverted position are determined. Effects of damping on these conditions are discussed.

A novel real-time data acquisition using an Excel spreadsheet in pendulum experiment tool with light-based timer

NASA Astrophysics Data System (ADS)

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.

Pendulum Mass Affects the Measurement of Articular Friction Coefficient

PubMed Central

Akelman, Matthew R.; Teeple, Erin; Machan, Jason T.; Crisco, Joseph J.; Jay, Gregory D.; Fleming, Braden C.

2012-01-01

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. PMID:23122223

Pendulum mass affects the measurement of articular friction coefficient.

PubMed

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.

Maxillary molar distalization: Pendulum and Fast-Back, comparison between two approaches for Class II malocclusion.

PubMed

Caprioglio, Alberto; Beretta, Matteo; Lanteri, Claudio

2011-01-01

To compare the dento-alveolar and skeletal effects produced by two different molar intraoral distalization appliances, Pendulum and Fast-Back, both followed by fixed appliances, in the treatment of Class II malocclusion. 41 patients for Pendulum (18 males and 23 females) and 35 for Fast-Back (14 males and 21 females) were selected, with a mean age at the start of treatment of 12.11 years in the Pendulum group and 13.3 for in the Fast-Back group. The durations of the distalization phase were 8 months in the Pendulum group and 9 months in the Fast-Back group, and the durations of the second phase of treatment with fixed appliances were 19 months in the Pendulum group and 20 months in the Fast-Back group. Lateral cephalograms were analyzed at 3 observation times: before treatment, after distalization and after comprehensive orthodontic treatment. During molar distalization the Pendulum subjects showed greater distal molar movement and less anchorage loss at both the premolars and maxillary incisors than the Fast-Back subjects. Pendulum and Fast-Back produced similar amounts of distal molar movement and overcorrection of molar relationship at the end of distalization though the Fast-Back induced a more bodily movement. Very little change occurred in the inclination of the mandibular plane at the end of the 2-phase treatment in both groups. At the end of treatment the maxillary first molars were on average 1mm more distal in the Pendulum group compared to the Fast-Back group, while the total molar correction was 3.2mm with 3.9° of distal inclination for the Pendulum and 2mm with 1.1° of mesial inclination for the Fast-Back. Both appliance were equally effective in inducing a satisfactory Class I relationship in 97.2% of the cases. The Pendulum and the Fast-Back induce similar dentoskeletal effects. The use of the two distalization devices, therefore, can be considered clinically equivalent. Copyright © 2011 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved.

Square-Wave Model for a Pendulum with Oscillating Suspension

ERIC Educational Resources Information Center

Yorke, Ellen D.

1978-01-01

Demonstrates that if a sinusoidal oscillation of the point of support of a pendulum is approximated by a square wave, a matrix method may be used to discuss parametric resonance and the stability of the inverted pendulum. (Author/SL)

Examining Functions in Mathematics and Science Using Computer Interfacing.

ERIC Educational Resources Information Center

Walton, Karen Doyle

1988-01-01

Introduces microcomputer interfacing as a method for explaining and demonstrating various aspects of the concept of function. Provides three experiments with illustrations and typical computer graphic displays: pendulum motion, pendulum study using two pendulums, and heat absorption and radiation. (YP)

Course of Near-hanging Victims Succumbed to Death: A Seven Year Study

PubMed Central

Mugadlimath, Anand B.; Zine, K.U.; Farooqui, Jamebaseer M.; Phalke, Balaji J.

2015-01-01

Introduction: Near hanging refers to victims who survive a hanging injury following attempted hanging, long enough to reach hospital. Delayed deaths in near hanging patients are mostly due to complication of hanging. The purpose of this study was to evaluate the demographics, mortality patterns and cause of delayed deaths in near hanging victims. Materials and Methods: In this study autopsy files over a seven year period from 2007 to 2013 were reviewed, and data of near hanging deaths (attempted hanging cases who succumbed to death and subjected for medicolegal autopsy) was extracted. Records of 14,000 autopsies was reviewed, and 10 deceased having died delayed deaths after near hanging episode were identified. In each case, the patients’ details, including gender, age, type of suspension, type of ligature material used for hanging and subsequent hanging mark produced were reviewed using autopsy reports and photographs taken during autopsy. Results: Demographic and pathological aspects of the each case discussed to throw light on autopsy findings in victims who died following near hanging. Complete suspension was present in 3 cases, while partial suspension was present in 7 cases. Survivals in delayed death after near hanging episode have ranged from 9 h to 72 d. Hypoxic encephalopathy was the most common cause of death, followed by pneumonia. Conclusion: Most of the near hanging patients did succumb to hypoxic encephalopathy; however, consolidation of lungs (pneumonia) was the next common cause of death reflecting need for aggressive oxygen therapy and selective resuscitation should be performed in all such cases. PMID:25954634

Control of Torsional Vibrations by Pendulum Masses

NASA Technical Reports Server (NTRS)

Stieglitz, Albert

1942-01-01

Various versions of pendulum masses have been developed abroad within the past few years by means of which resonant vibrations of rotating shafts can be eliminated at a given tuning. They are already successfully employed on radial engines in the form of pendulous counterweights. Compared with the commonly known torsional vibration dampers, the pendulum masses have the advantage of being structurally very simple, requiring no internal damping and being capable of completely eliminating certain vibrations. Unexplained, so far, remains the problem of behavior of pendulum masses in other critical zones to which they are not tuned, their dynamic behavior at some tuning other than in resonance, and their effect within a compound vibration system and at simultaneous application of several differently tuned pendulous masses. These problems are analyzed in the present report. The results constitute an enlargement of the scope of application of pendulum masses, especially for in-line engines. Among other things it is found that the natural frequency of a system can be raised by means of a correspondingly tuned pendulum mass. The formulas necessary for the design of any practical version are developed, and a pendulum mass having two different natural frequencies simultaneously is described.

A novel pendulum test for measuring roller chain efficiency

NASA Astrophysics Data System (ADS)

Wragge-Morley, R.; Yon, J.; Lock, R.; Alexander, B.; Burgess, S.

2018-07-01

This paper describes a novel pendulum decay test for determining the transmission efficiency of chain drives. The test involves releasing a pendulum with an initial potential energy and measuring its decaying oscillations: under controlled conditions the decay reveals the losses in the transmission to a high degree of accuracy. The main advantage over motorised rigs is that there are significantly fewer sources of friction and inertia and hence measurement error. The pendulum rigs have an accuracy around 0.6% for the measurement of the coefficient of friction, giving an accuracy of transmission efficiency measurement around 0.012%. A theoretical model of chain friction combined with the equations of motion enables the coefficient of friction to be determined from the decay rate of pendulum velocity. The pendulum rigs operate at relatively low speeds. However, they allow an accurate determination of the coefficient of friction to estimate transmission efficiency at higher speeds. The pendulum rig revealed a previously undetected rocking behaviour in the chain links at very small articulation angles. In this regime, the link interfaces were observed to roll against one another rather than slide. This observation indicates that a very high-efficiency transmission can be achieved if the articulation angle is very low.

Approximated Stable Inversion for Nonlinear Systems with Nonhyperbolic Internal Dynamics. Revised

NASA Technical Reports Server (NTRS)

Devasia, Santosh

1999-01-01

A technique to achieve output tracking for nonminimum phase nonlinear systems with non- hyperbolic internal dynamics is presented. The present paper integrates stable inversion techniques (that achieve exact-tracking) with approximation techniques (that modify the internal dynamics) to circumvent the nonhyperbolicity of the internal dynamics - this nonhyperbolicity is an obstruction to applying presently available stable inversion techniques. The theory is developed for nonlinear systems and the method is applied to a two-cart with inverted-pendulum example.

Quadriceps femoris spasticity in children with cerebral palsy: measurement with the pendulum test and relationship with gait abnormalities.

PubMed

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.

Comparison of the effects produced by headgear and pendulum appliances followed by fixed orthodontic treatment.

PubMed

Angelieri, Fernanda; de Almeida, Renato Rodrigues; Janson, Guilherme; Castanha Henriques, José Fernando; Pinzan, Arnaldo

2008-12-01

This study compared the effects produced by two different molar distalizers, namely cervical headgear (CHG) and the intraoral pendulum appliance, associated with fixed orthodontic appliances. The headgear group comprised 30 patients (19 females, 11 males), with an initial age of 13.07 years [standard deviation (SD) = 1.3], treated with CHG and fixed orthodontic appliances for a mean period of 3.28 years, and the pendulum group 22 patients (15 females, 7 males), with initial age of 13.75 years (SD = 1.86), treated with the pendulum appliance followed by fixed orthodontic appliances for a mean period of 4.12 years. Lateral cephalograms were taken at the start (T1) and on completion (T2) of orthodontic treatment. The pendulum and CHG groups were similar as to initial age, severity of the Class II malocclusion, gender distribution, initial cephalometric characteristics, and initial and final treatment priority index (TPI). Only treatment time was not similar between the groups, with a need for annualization for data for the pendulum group. The data were compared with independent t-tests. There was significantly greater restriction of maxillary forward growth and improvement of the skeletal maxillomandibular relationship in the CHG group (P < 0.05). The maxillary molars were more mesially tipped and extruded and the mandibular molars more uprighted in the CHG group compared with the pendulum group (P < 0.05). There was more labial tipping of the mandibular incisors and greater overbite reduction in the pendulum group. The pendulum appliance produced only dentoalveolar effects, different from the CHG appliance, which restricted maxillary forward displacement, thus improving the skeletal maxillomandibular relationship.

Analyzing spring pendulum phenomena with a smart-phone acceleration sensor

NASA Astrophysics Data System (ADS)

Kuhn, Jochen; Vogt, Patrik

2012-11-01

This paper describes two further pendulum experiments using the acceleration sensor of a smartphone in this column (for earlier contributions concerning this topic, including the description of the operation and use of the acceleration sensor, see Refs. 1 and 2). In this paper we focus on analyzing spring pendulum phenomena. Therefore two spring pendulum experiments will be described in which a smartphone is used as a pendulum body and SPARKvue3 software is used in conjunction with an iPhone or an iPod touch, or the Accelogger4 app for an Android device.1,2 As described in Ref. 1, the values measured by the smartphone are subsequently exported to a spreadsheet application (e.g., MS Excel) for analysis.

Creatinine sensor based on a molecularly imprinted polymer-modified hanging mercury drop electrode.

PubMed

Lakshmi, Dhana; Prasad, Bhim Bali; Sharma, Piyush Sindhu

2006-09-15

Molecularly imprinted polymers (MIP) have been elucidated to work as artificial receptors. In our present study, a MIP was applied as a molecular recognition element to a chemical sensor. We have constructed a creatinine sensor based on a MIP layer selective for creatinine and its differential pulse, cathodic stripping voltammetric detection (DPCSV) on a hanging mercury drop electrode (HMDE). The creatinine sensor was fabricated by the drop coating of dimethylformamide (DMF) solution of a creatinine-imprinted polymer onto the surface of HMDE. The modified-HMDE, preanodised in neutral medium at +0.4V versus Ag/AgCl for 120s, exhibited a marked enhancement in DPCSV current in comparison to the less anodised (

Magnetic effect in the test of the weak equivalence principle using a rotating torsion pendulum

NASA Astrophysics Data System (ADS)

Zhu, Lin; Liu, Qi; Zhao, Hui-Hui; Yang, Shan-Qing; Luo, Pengshun; Shao, Cheng-Gang; Luo, Jun

2018-04-01

The high precision test of the weak equivalence principle (WEP) using a rotating torsion pendulum requires thorough analysis of systematic effects. Here we investigate one of the main systematic effects, the coupling of the ambient magnetic field to the pendulum. It is shown that the dominant term, the interaction between the average magnetic field and the magnetic dipole of the pendulum, is decreased by a factor of 1.1 × 104 with multi-layer magnetic shield shells. The shield shells reduce the magnetic field to 1.9 × 10-9 T in the transverse direction so that the dipole-interaction limited WEP test is expected at η ≲ 10-14 for a pendulum dipole less than 10-9 A m2. The high-order effect, the coupling of the magnetic field gradient to the magnetic quadrupole of the pendulum, would also contribute to the systematic errors for a test precision down to η ˜ 10-14.

Magnetic effect in the test of the weak equivalence principle using a rotating torsion pendulum.

PubMed

Zhu, Lin; Liu, Qi; Zhao, Hui-Hui; Yang, Shan-Qing; Luo, Pengshun; Shao, Cheng-Gang; Luo, Jun

2018-04-01

The high precision test of the weak equivalence principle (WEP) using a rotating torsion pendulum requires thorough analysis of systematic effects. Here we investigate one of the main systematic effects, the coupling of the ambient magnetic field to the pendulum. It is shown that the dominant term, the interaction between the average magnetic field and the magnetic dipole of the pendulum, is decreased by a factor of 1.1 × 10 4 with multi-layer magnetic shield shells. The shield shells reduce the magnetic field to 1.9 × 10 -9 T in the transverse direction so that the dipole-interaction limited WEP test is expected at η ≲ 10 -14 for a pendulum dipole less than 10 -9 A m 2 . The high-order effect, the coupling of the magnetic field gradient to the magnetic quadrupole of the pendulum, would also contribute to the systematic errors for a test precision down to η ∼ 10 -14 .

Development of Gravity Acceleration Measurement Using Simple Harmonic Motion Pendulum Method Based on Digital Technology and Photogate Sensor

NASA Astrophysics Data System (ADS)

Yulkifli; Afandi, Zurian; Yohandri

2018-04-01

Development of gravitation acceleration measurement using simple harmonic motion pendulum method, digital technology and photogate sensor has been done. Digital technology is more practical and optimizes the time of experimentation. The pendulum method is a method of calculating the acceleration of gravity using a solid ball that connected to a rope attached to a stative pole. The pendulum is swung at a small angle resulted a simple harmonic motion. The measurement system consists of a power supply, Photogate sensors, Arduino pro mini and seven segments. The Arduino pro mini receives digital data from the photogate sensor and processes the digital data into the timing data of the pendulum oscillation. The calculation result of the pendulum oscillation time is displayed on seven segments. Based on measured data, the accuracy and precision of the experiment system are 98.76% and 99.81%, respectively. Based on experiment data, the system can be operated in physics experiment especially in determination of the gravity acceleration.

Instability dynamics and breather formation in a horizontally shaken pendulum chain.

PubMed

Xu, Y; Alexander, T J; Sidhu, H; Kevrekidis, P G

2014-10-01

Inspired by the experimental results of Cuevas et al. [Phys. Rev. Lett. 102, 224101 (2009)], we consider theoretically the behavior of a chain of planar rigid pendulums suspended in a uniform gravitational field and subjected to a horizontal periodic driving force applied to the pendulum pivots. We characterize the motion of a single pendulum, finding bistability near the fundamental resonance and near the period-3 subharmonic resonance. We examine the development of modulational instability in a driven pendulum chain and find both a critical chain length and a critical frequency for the appearance of the instability. We study the breather solutions and show their connection to the single-pendulum dynamics and extend our analysis to consider multifrequency breathers connected to the period-3 periodic solution, showing also the possibility of stability in these breather states. Finally we examine the problem of breather generation and demonstrate a robust scheme for generation of on-site and off-site breathers.

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters.

PubMed

Nagao, N; Yokota, S; Komurasaki, K; Arakawa, Y

2007-11-01

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors [axial and horizontal (transverse) direction thrusts] of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%) in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of +/-2.3 degrees was measured with the error of +/-0.2 degrees under the typical operating conditions for the thruster.

Mathematic study of the rotor motion with a pendulum selfbalancing device

NASA Astrophysics Data System (ADS)

Ivkina, O. P.; Ziyakaev, G. R.; Pashkov, E. N.

2016-09-01

The rotary machines used in manufacturing may become unbalanced leading to vibration. In some cases, the problem may be solved by installing self-balancing devices (SBDs). Certain factors, however, exhibit a pronounced effect on the efficiency of these devices. The objective of the research comprised of establishing the most beneficial spatial position of pendulums to minimize the necessary time to repair the rotor unbalance. The mathematical research of the motion of a rotor with pendulum SBDs in the situation of their misalignment was undertaken. This objective was achieved by using the Lagrange equations of the second type. The analysis identified limiting cases of location of the rotor unbalance vector and the vector of housing's unbalance relative to each other, as well as the minimum capacity of the pendulum. When determining pendulums ’ parameters during the SBD design process, it is necessary to take into account the rotor unbalance and the unbalance of the machine body, which is caused by the misalignment of rotor axis and pendulum's axis of rotation.

Development of a software-hardware complex for studying the process of grinding by a pendulum deformer

NASA Astrophysics Data System (ADS)

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.

49 CFR 572.123 - Neck assembly and test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... with respect to the pendulum's longitudinal centerline between 74 degrees and 92 degrees. Within this... direction of preimpact flight with respect to the pendulum's longitudinal centerline between 85 degrees and... contact between the pendulum striker plate and the honeycomb material. (c) Test procedure. The test...

49 CFR 572.123 - Neck assembly and test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... with respect to the pendulum's longitudinal centerline between 74 degrees and 92 degrees. Within this... direction of preimpact flight with respect to the pendulum's longitudinal centerline between 85 degrees and... contact between the pendulum striker plate and the honeycomb material. (c) Test procedure. The test...

49 CFR 572.123 - Neck assembly and test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... with respect to the pendulum's longitudinal centerline between 74 degrees and 92 degrees. Within this... direction of preimpact flight with respect to the pendulum's longitudinal centerline between 85 degrees and... contact between the pendulum striker plate and the honeycomb material. (c) Test procedure. The test...

49 CFR 572.123 - Neck assembly and test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... with respect to the pendulum's longitudinal centerline between 74 degrees and 92 degrees. Within this... direction of preimpact flight with respect to the pendulum's longitudinal centerline between 85 degrees and... contact between the pendulum striker plate and the honeycomb material. (c) Test procedure. The test...

49 CFR 572.123 - Neck assembly and test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... with respect to the pendulum's longitudinal centerline between 74 degrees and 92 degrees. Within this... direction of preimpact flight with respect to the pendulum's longitudinal centerline between 85 degrees and... contact between the pendulum striker plate and the honeycomb material. (c) Test procedure. The test...

Pendulum Phenomena and the Assessment of Scientific Inquiry Capabilities

ERIC Educational Resources Information Center

Zachos, Paul

2004-01-01

Phenomena associated with the "pendulum" present numerous opportunities for assessing higher order human capabilities related to "scientific inquiry" and the "discovery" of natural law. This paper illustrates how systematic "assessment of scientific inquiry capabilities", using "pendulum" phenomena, can provide a useful tool for classroom teachers…

The Pendulum Equation

ERIC Educational Resources Information Center

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…

Equilibrium and Stability of a Pendulum in an Orbiting Spaceship.

ERIC Educational Resources Information Center

Blitzer, Leon

1979-01-01

Investigates the behavior of a simple pendulum attached to a fixed point inside a satellite moving in a circular orbit about the earth. It is found that the number of equilibrium positions depends on the length of the pendulum and the location of the point of attachment. (HM)

49 CFR 581.6 - Conditions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... the vehicle if they are optional equipment. (b) Pendulum test conditions. The following conditions apply to the pendulum test procedures of § 581.7 (a) and (b). (1) The test device consists of a block... 1963. From the point of release of the device until the onset of rebound, the pendulum suspension...

49 CFR 572.17 - Neck.

Code of Federal Regulations, 2012 CFR

2012-10-01

... (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline a... distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at time T as...

49 CFR 572.113 - Neck assembly.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Using neck brackets 78051-303 and -307, mount the head/neck assembly to the part 572 pendulum test... to the plane of motion of the pendulum's longitudinal centerline (see § 572.33, Figure 20, except... (horizontal surface at the base of the skull) rotation with respect to the pendulum's longitudinal centerline...

49 CFR 572.7 - Neck.

Code of Federal Regulations, 2014 CFR

2014-10-01

... paragraph (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline... the straight line distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at...

49 CFR 581.6 - Conditions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... the vehicle if they are optional equipment. (b) Pendulum test conditions. The following conditions apply to the pendulum test procedures of § 581.7 (a) and (b). (1) The test device consists of a block... 1963. From the point of release of the device until the onset of rebound, the pendulum suspension...

49 CFR 572.143 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... subpart, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal... rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are... of preimpact flight with respect to the pendulum's longitudinal centerline between 83 degrees and 93...

49 CFR 572.36 - Test conditions and instrumentation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... be mounted with its sensitive axis colinear with the pendulum's longitudinal centerline. (h) The... acceleration—Class 1000 (2) Neck forces—Class 1000 (3) Neck moments—Class 600 (4) Neck pendulum acceleration—Class 60 (5) Thorax and thorax pendulum acceleration—Class 180 (6) Thorax deflection—Class 180 (7) Knee...

49 CFR 572.17 - Neck.

Code of Federal Regulations, 2014 CFR

2014-10-01

... (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline a... distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at time T as...

49 CFR 572.133 - Neck assembly and test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... pendulum's longitudinal centerline between 77 degrees and 91 degrees. During the time interval while the... respect to the pendulum's longitudinal centerline between 99 degrees and 114 degrees. During the time... force to occipital condyle. (3) Time-zero is defined as the time of initial contact between the pendulum...

49 CFR 572.17 - Neck.

Code of Federal Regulations, 2013 CFR

2013-10-01

... (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline a... distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at time T as...

49 CFR 572.113 - Neck assembly.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Using neck brackets 78051-303 and -307, mount the head/neck assembly to the part 572 pendulum test... to the plane of motion of the pendulum's longitudinal centerline (see § 572.33, Figure 20, except... (horizontal surface at the base of the skull) rotation with respect to the pendulum's longitudinal centerline...

49 CFR 572.17 - Neck.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline a... distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at time T as...

49 CFR 572.133 - Neck assembly and test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... pendulum's longitudinal centerline between 77 degrees and 91 degrees. During the time interval while the... respect to the pendulum's longitudinal centerline between 99 degrees and 114 degrees. During the time... force to occipital condyle. (3) Time-zero is defined as the time of initial contact between the pendulum...

49 CFR 581.6 - Conditions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... the vehicle if they are optional equipment. (b) Pendulum test conditions. The following conditions apply to the pendulum test procedures of § 581.7 (a) and (b). (1) The test device consists of a block... 1963. From the point of release of the device until the onset of rebound, the pendulum suspension...

49 CFR 572.153 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... subpart shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal... shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline... section, on the pendulum so the midsagittal plane of the headform is vertical and coincides with the plane...

49 CFR 572.143 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... subpart, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal... rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are... of preimpact flight with respect to the pendulum's longitudinal centerline between 83 degrees and 93...

49 CFR 572.133 - Neck assembly and test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... pendulum's longitudinal centerline between 77 degrees and 91 degrees. During the time interval while the... respect to the pendulum's longitudinal centerline between 99 degrees and 114 degrees. During the time... force to occipital condyle. (3) Time-zero is defined as the time of initial contact between the pendulum...

49 CFR 572.173 - Neck assembly and test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... respect to the pendulum's longitudinal centerline between 76 degrees and 90 degrees. During the time..., referenced in Figure T3, shall rotate in the direction of preimpact flight with respect to the pendulum's... occipital condyle. (3) Time zero is defined as the time of initial contact between the pendulum striker...

49 CFR 581.6 - Conditions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the vehicle if they are optional equipment. (b) Pendulum test conditions. The following conditions apply to the pendulum test procedures of § 581.7 (a) and (b). (1) The test device consists of a block... 1963. From the point of release of the device until the onset of rebound, the pendulum suspension...

49 CFR 581.6 - Conditions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... the vehicle if they are optional equipment. (b) Pendulum test conditions. The following conditions apply to the pendulum test procedures of § 581.7 (a) and (b). (1) The test device consists of a block... 1963. From the point of release of the device until the onset of rebound, the pendulum suspension...

49 CFR 572.173 - Neck assembly and test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... respect to the pendulum's longitudinal centerline between 76 degrees and 90 degrees. During the time..., referenced in Figure T3, shall rotate in the direction of preimpact flight with respect to the pendulum's... occipital condyle. (3) Time zero is defined as the time of initial contact between the pendulum striker...

49 CFR 572.153 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2012 CFR

2012-10-01

... subpart shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal... shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline... section, on the pendulum so the midsagittal plane of the headform is vertical and coincides with the plane...

Conical Pendulum--Linearization Analyses

ERIC Educational Resources Information Center

Dean, Kevin; Mathew, Jyothi

2016-01-01

A theoretical analysis is presented, showing the derivations of seven different linearization equations for the conical pendulum period "T", as a function of radial and angular parameters. Experimental data obtained over a large range of fixed conical pendulum lengths (0.435 m-2.130 m) are plotted with the theoretical lines and…

49 CFR 572.17 - Neck.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline a... distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at time T as...

49 CFR 572.113 - Neck assembly.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Using neck brackets 78051-303 and -307, mount the head/neck assembly to the part 572 pendulum test... to the plane of motion of the pendulum's longitudinal centerline (see § 572.33, Figure 20, except... (horizontal surface at the base of the skull) rotation with respect to the pendulum's longitudinal centerline...

49 CFR 572.7 - Neck.

Code of Federal Regulations, 2012 CFR

2012-10-01

... paragraph (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline... the straight line distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at...

49 CFR 572.143 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... subpart, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal... rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are... of preimpact flight with respect to the pendulum's longitudinal centerline between 83 degrees and 93...

49 CFR 572.173 - Neck assembly and test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... respect to the pendulum's longitudinal centerline between 76 degrees and 90 degrees. During the time..., referenced in Figure T3, shall rotate in the direction of preimpact flight with respect to the pendulum's... occipital condyle. (3) Time zero is defined as the time of initial contact between the pendulum striker...

49 CFR 572.133 - Neck assembly and test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... pendulum's longitudinal centerline between 77 degrees and 91 degrees. During the time interval while the... respect to the pendulum's longitudinal centerline between 99 degrees and 114 degrees. During the time... force to occipital condyle. (3) Time-zero is defined as the time of initial contact between the pendulum...

49 CFR 572.153 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... subpart shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal... shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline... section, on the pendulum so the midsagittal plane of the headform is vertical and coincides with the plane...

49 CFR 572.133 - Neck assembly and test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... pendulum's longitudinal centerline between 77 degrees and 91 degrees. During the time interval while the... respect to the pendulum's longitudinal centerline between 99 degrees and 114 degrees. During the time... force to occipital condyle. (3) Time-zero is defined as the time of initial contact between the pendulum...

49 CFR 572.113 - Neck assembly.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Using neck brackets 78051-303 and -307, mount the head/neck assembly to the part 572 pendulum test... to the plane of motion of the pendulum's longitudinal centerline (see § 572.33, Figure 20, except... (horizontal surface at the base of the skull) rotation with respect to the pendulum's longitudinal centerline...

49 CFR 572.7 - Neck.

Code of Federal Regulations, 2013 CFR

2013-10-01

... paragraph (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline... the straight line distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at...

49 CFR 572.153 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... subpart shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal... shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline... section, on the pendulum so the midsagittal plane of the headform is vertical and coincides with the plane...

49 CFR 572.36 - Test conditions and instrumentation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... be mounted with its sensitive axis colinear with the pendulum's longitudinal centerline. (h) The... acceleration—Class 1000 (2) Neck forces—Class 1000 (3) Neck moments—Class 600 (4) Neck pendulum acceleration—Class 60 (5) Thorax and thorax pendulum acceleration—Class 180 (6) Thorax deflection—Class 180 (7) Knee...

Experiments with a Magnetically Controlled Pendulum

ERIC Educational Resources Information Center

Kraftmakher, Yaakov

2007-01-01

A magnetically controlled pendulum is used for observing free and forced oscillations, including nonlinear oscillations and chaotic motion. A data-acquisition system stores the data and displays time series of the oscillations and related phase plane plots, Poincare maps, Fourier spectra and histograms. The decay constant of the pendulum can be…

49 CFR 572.7 - Neck.

Code of Federal Regulations, 2010 CFR

2010-10-01

... paragraph (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline... the straight line distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at...

49 CFR 572.153 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... subpart shall rotate in the direction of pre-impact flight with respect to the pendulum's longitudinal... shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal centerline... section, on the pendulum so the midsagittal plane of the headform is vertical and coincides with the plane...

49 CFR 572.113 - Neck assembly.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Using neck brackets 78051-303 and -307, mount the head/neck assembly to the part 572 pendulum test... to the plane of motion of the pendulum's longitudinal centerline (see § 572.33, Figure 20, except... (horizontal surface at the base of the skull) rotation with respect to the pendulum's longitudinal centerline...

49 CFR 572.7 - Neck.

Code of Federal Regulations, 2011 CFR

2011-10-01

... paragraph (c) of this section, the head shall rotate in reference to the pendulum's longitudinal centerline... the straight line distance between (1) the position relative to the pendulum arm of the head center of gravity at time zero, and (2) the position relative to the pendulum arm of the head center of gravity at...

49 CFR 572.36 - Test conditions and instrumentation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... be mounted with its sensitive axis colinear with the pendulum's longitudinal centerline. (h) The... acceleration—Class 1000 (2) Neck forces—Class 1000 (3) Neck moments—Class 600 (4) Neck pendulum acceleration—Class 60 (5) Thorax and thorax pendulum acceleration—Class 180 (6) Thorax deflection—Class 180 (7) Knee...

49 CFR 572.36 - Test conditions and instrumentation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... be mounted with its sensitive axis colinear with the pendulum's longitudinal centerline. (h) The... acceleration—Class 1000 (2) Neck forces—Class 1000 (3) Neck moments—Class 600 (4) Neck pendulum acceleration—Class 60 (5) Thorax and thorax pendulum acceleration—Class 180 (6) Thorax deflection—Class 180 (7) Knee...

49 CFR 572.143 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2011 CFR

2011-10-01

... subpart, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal... rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are... of preimpact flight with respect to the pendulum's longitudinal centerline between 83 degrees and 93...

49 CFR 572.36 - Test conditions and instrumentation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... be mounted with its sensitive axis colinear with the pendulum's longitudinal centerline. (h) The... acceleration—Class 1000 (2) Neck forces—Class 1000 (3) Neck moments—Class 600 (4) Neck pendulum acceleration—Class 60 (5) Thorax and thorax pendulum acceleration—Class 180 (6) Thorax deflection—Class 180 (7) Knee...

49 CFR 572.143 - Neck-headform assembly and test procedure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... subpart, shall rotate in the direction of preimpact flight with respect to the pendulum's longitudinal... rotation data channels are defined to be zero when the longitudinal centerline of the neck and pendulum are... of preimpact flight with respect to the pendulum's longitudinal centerline between 83 degrees and 93...

"Time: What Is It that It Can Be Measured?"

ERIC Educational Resources Information Center

Raju, C. K.

2006-01-01

Experiments with the simple pendulum are easy, but its motion is nevertheless confounded with simple harmonic motion. However, refined theoretical models of the pendulum can, today, be easily taught using software like CALCODE. Similarly, the cycloidal pendulum is isochronous only in simplified theory. But what "are" theoretically equal intervals…

An analytical approach to the external force-free motion of pendulums on surfaces of constant curvature

NASA Astrophysics Data System (ADS)

Rubio, Rafael M.; Salamanca, Juan J.

2018-07-01

The dynamics of external force free motion of pendulums on surfaces of constant Gaussian curvature is addressed when the pivot moves along a geodesic obtaining the Lagrangian of the system. As an application it is possible the study of elastic and quantum pendulums.

The Pendulum and the Calculus.

ERIC Educational Resources Information Center

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…

Multi-directional energy harvesting by piezoelectric cantilever-pendulum with internal resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, J.; Tang, J., E-mail: jtang@engr.uconn.edu

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.

Design and Flight Test of a Cable Angle Feedback Control System for Improving Helicopter Slung Load Operations at Low Speed

DTIC Science & Technology

2014-04-01

improve the damping of the load pendulum motions, but the load feedback generally had the effect of making the load feel heavier to the pilot [28...0.25 2 1000lbs 16,000lbs 0.06 Another important parameter is the slung load pendulum frequency. Using a simple pendulum model, this natural...the expected yaw and heave modes. The presence of the load adds oscillatory pendulum modes in the pitch and roll axes, as expected. Table 2-3

A simple, low-cost, data logging pendulum built from a computer mouse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gintautas, Vadas; Hubler, Alfred

Lessons and homework problems involving a pendulum are often a big part of introductory physics classes and laboratory courses from high school to undergraduate levels. Although laboratory equipment for pendulum experiments is commercially available, it is often expensive and may not be affordable for teachers on fixed budgets, particularly in developing countries. We present a low-cost, easy-to-build rotary sensor pendulum using the existing hardware in a ball-type computer mouse. We demonstrate how this apparatus may be used to measure both the frequency and coefficient of damping of a simple physical pendulum. This easily constructed laboratory equipment makes it possible formore » all students to have hands-on experience with one of the most important simple physical systems.« less

Translation of time-reversal violation in the neutral K-meson system into a table-top mechanical system

NASA Astrophysics Data System (ADS)

Reiser, Andreas; Schubert, Klaus R.; Stiewe, Jürgen

2012-08-01

Weak interactions break time-reversal (T) symmetry in the two-state system of neutral K-mesons. We present and discuss a two-state mechanical system, i.e. a Foucault-type pendulum on a rotating table, for a full representation of {K^0}{{\\overlineK}{}^0} transitions by the pendulum motions including T violation. The pendulum moves with two different oscillation frequencies and two different magnetic dampings. Its equation of motion is identical to the differential equation for the real part of the CPT-symmetric K-meson wavefunction. The pendulum is able to represent microscopic CP and T violation with CPT symmetry owing to the macroscopic Coriolis force, which breaks the symmetry under reversal-of-motion. Video clips of the pendulum motions are given as supplementary material.

Ceramic Life Prediction Parameters

DTIC Science & Technology

1980-05-01

preferential. A standard creep testing Satec machine with a modified load train assembly was used for tensile stress-rupture testing. The specimen is...to the standard Satec machine head which includes crossed (90°) knife edges. The assembly procedure includes hanging the load train parts from...the Satec head as influenced by gravity. At this point the lower Satec crossarm is lowered to snub the train in this position. The load train

Three-dimensional friction measurement during hip simulation

PubMed Central

Braun, Steffen; Al-Salehi, Loay; Reinders, Joern; Mueller, Ulrike; Kretzer, J. Philippe

2017-01-01

Objectives Wear of total hip replacements has been the focus of many studies. However, frictional effects, such as high loading on intramodular connections or the interface to the bone, as well as friction associated squeaking have recently increased interest about the amount of friction that is generated during daily activities. The aim of this study was thus to establish and validate a three-dimensional friction setup under standardized conditions. Materials and methods A standard hip simulator was modified to allow for high precision measurements of small frictional effects in the hip during three-dimensional hip articulation. The setup was verified by an ideal hydrostatic bearing and validated with a static-load physical pendulum and an extension-flexion rotation with a dynamic load profile. Additionally, a pendulum model was proposed for screening measurement of frictional effects based on the damping behavior of the angular oscillation without the need for any force/moment transducer. Finally, three-dimensional friction measurements have been realized for ceramic-on-polyethylene bearings of three different sizes (28, 36 and 40 mm). Results A precision of less than 0.2 Nm during three-dimensional friction measurements was reported, while increased frictional torque (resultant as well as taper torque) was measured for larger head diameters. These effects have been confirmed by simple pendulum tests and the theoretical model. A comparison with current literature about friction measurements is presented. Conclusions This investigation of friction is able to provide more information about a field that has been dominated by the reduction of wear. It should be considered in future pre-clinical testing protocols given by international organizations of standardization. PMID:28886102

Three-dimensional friction measurement during hip simulation.

PubMed

Sonntag, Robert; Braun, Steffen; Al-Salehi, Loay; Reinders, Joern; Mueller, Ulrike; Kretzer, J Philippe

2017-01-01

Wear of total hip replacements has been the focus of many studies. However, frictional effects, such as high loading on intramodular connections or the interface to the bone, as well as friction associated squeaking have recently increased interest about the amount of friction that is generated during daily activities. The aim of this study was thus to establish and validate a three-dimensional friction setup under standardized conditions. A standard hip simulator was modified to allow for high precision measurements of small frictional effects in the hip during three-dimensional hip articulation. The setup was verified by an ideal hydrostatic bearing and validated with a static-load physical pendulum and an extension-flexion rotation with a dynamic load profile. Additionally, a pendulum model was proposed for screening measurement of frictional effects based on the damping behavior of the angular oscillation without the need for any force/moment transducer. Finally, three-dimensional friction measurements have been realized for ceramic-on-polyethylene bearings of three different sizes (28, 36 and 40 mm). A precision of less than 0.2 Nm during three-dimensional friction measurements was reported, while increased frictional torque (resultant as well as taper torque) was measured for larger head diameters. These effects have been confirmed by simple pendulum tests and the theoretical model. A comparison with current literature about friction measurements is presented. This investigation of friction is able to provide more information about a field that has been dominated by the reduction of wear. It should be considered in future pre-clinical testing protocols given by international organizations of standardization.

What Makes the Foucault Pendulum Move among the Stars?

ERIC Educational Resources Information Center

Phillips, Norman

2004-01-01

Foucault's pendulum exhibition in 1851 occurred in an era now known by development of the theorems of Coriolis and the formulation of dynamical meteorology by Ferrel. Yet today the behavior of the pendulum is often misunderstood. The existence of a horizontal component of Newtonian gravitation is essential for understanding the behavior with…

49 CFR 572.189 - Instrumentation and test conditions.

Code of Federal Regulations, 2014 CFR

2014-10-01

.... The sum mass of the attachments and 1/3 cable mass must not exceed 5 percent of the total pendulum... filtered CFC 180; (3)Neck and lumbar spine pendulum accelerations—Digitally filtered CFC 60; (4) Pelvis... 180. (j)(1) Filter the pendulum acceleration data using a SAE J211 CFC 60 filter. (2) Determine the...

49 CFR 572.189 - Instrumentation and test conditions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... mass of the attachments and 1/3 cable mass must not exceed 5 percent of the total pendulum mass. No... lumbar spine pendulum accelerations—Digitally filtered CFC 60; (4) Pelvis, shoulder, thorax without arm...—Digitally filtered at CFC 600; (6) Thorax deflection—Digitally filtered CFC 180. (j)(1) Filter the pendulum...

49 CFR 572.33 - Neck.

Code of Federal Regulations, 2013 CFR

2013-10-01

... (b) of this section, on a rigid pendulum as shown in Figure 22 so that the head's midsagittal plane is vertical and coincides with the plane of motion of the pendulum's longitudinal axis. ER02JN11.011 (4) Release the pendulum and allow it to fall freely from a height such that the tangential velocity...

49 CFR 572.189 - Instrumentation and test conditions.

Code of Federal Regulations, 2013 CFR

2013-10-01

.... The sum mass of the attachments and 1/3 cable mass must not exceed 5 percent of the total pendulum... filtered CFC 180; (3)Neck and lumbar spine pendulum accelerations—Digitally filtered CFC 60; (4) Pelvis... 180. (j)(1) Filter the pendulum acceleration data using a SAE J211 CFC 60 filter. (2) Determine the...

49 CFR 572.35 - Limbs.

Code of Federal Regulations, 2014 CFR

2014-10-01

... in accordance with paragraph (b)(2) of this section, at 6.9 ft/sec ±0.10 ft/sec by the pendulum defined in § 572.36(b), the peak knee impact force, which is a product of pendulum mass and acceleration... the femur load cell simulator. (v) Guide the pendulum so that there is no significant lateral...

49 CFR 572.33 - Neck.

Code of Federal Regulations, 2011 CFR

2011-10-01

... (b) of this section, on a rigid pendulum as shown in Figure 22 so that the head's midsagittal plane is vertical and coincides with the plane of motion of the pendulum's longitudinal axis. EC01AU91.165 (4) Release the pendulum and allow it to fall freely from a height such that the tangential velocity...

49 CFR 572.35 - Limbs.

Code of Federal Regulations, 2013 CFR

2013-10-01

... in accordance with paragraph (b)(2) of this section, at 6.9 ft/sec ±0.10 ft/sec by the pendulum defined in § 572.36(b), the peak knee impact force, which is a product of pendulum mass and acceleration... the femur load cell simulator. (v) Guide the pendulum so that there is no significant lateral...

49 CFR 572.189 - Instrumentation and test conditions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... mass of the attachments and 1/3 cable mass must not exceed 5 percent of the total pendulum mass. No... lumbar spine pendulum accelerations—Digitally filtered CFC 60; (4) Pelvis, shoulder, thorax without arm...—Digitally filtered at CFC 600; (6) Thorax deflection—Digitally filtered CFC 180. (j)(1) Filter the pendulum...

49 CFR 572.33 - Neck.

Code of Federal Regulations, 2012 CFR

2012-10-01

... (b) of this section, on a rigid pendulum as shown in Figure 22 so that the head's midsagittal plane is vertical and coincides with the plane of motion of the pendulum's longitudinal axis. ER02JN11.011 (4) Release the pendulum and allow it to fall freely from a height such that the tangential velocity...

49 CFR 572.35 - Limbs.

Code of Federal Regulations, 2012 CFR

2012-10-01

... in accordance with paragraph (b)(2) of this section, at 6.9 ft/sec ±0.10 ft/sec by the pendulum defined in § 572.36(b), the peak knee impact force, which is a product of pendulum mass and acceleration... the femur load cell simulator. (v) Guide the pendulum so that there is no significant lateral...

49 CFR 572.33 - Neck.

Code of Federal Regulations, 2010 CFR

2010-10-01

... (b) of this section, on a rigid pendulum as shown in Figure 22 so that the head's midsagittal plane is vertical and coincides with the plane of motion of the pendulum's longitudinal axis. EC01AU91.165 (4) Release the pendulum and allow it to fall freely from a height such that the tangential velocity...

49 CFR 572.183 - Neck assembly.

Code of Federal Regulations, 2013 CFR

2013-10-01

... subpart E pendulum test fixture as shown in Figure U2-A in appendix A to this subpart, so that the... pendulum longitudinal centerline shown in Figure U2-A. Torque the half-spherical screws (175-2004) located... equivalent; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact...

49 CFR 572.183 - Neck assembly.

Code of Federal Regulations, 2012 CFR

2012-10-01

... subpart E pendulum test fixture as shown in Figure U2-A in appendix A to this subpart, so that the... pendulum longitudinal centerline shown in Figure U2-A. Torque the half-spherical screws (175-2004) located... equivalent; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact...

49 CFR 572.189 - Instrumentation and test conditions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... mass of the attachments and 1/3 cable mass must not exceed 5 percent of the total pendulum mass. No... lumbar spine pendulum accelerations—Digitally filtered CFC 60; (4) Pelvis, shoulder, thorax without arm...—Digitally filtered at CFC 600; (6) Thorax deflection—Digitally filtered CFC 180. (j)(1) Filter the pendulum...

Analysis of the Pendular and Pitch Motions of a Driven Three-Dimensional Pendulum

ERIC Educational Resources Information Center

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…

Explicit Analytical Solution of a Pendulum with Periodically Varying Length

ERIC Educational Resources Information Center

Yang, Tianzhi; Fang, Bo; Li, Song; Huang, Wenhu

2010-01-01

A pendulum with periodically varying length is an interesting physical system. It has been studied by some researchers using traditional perturbation methods (for example, the averaging method). But due to the limitation of the conventional perturbation methods, the solutions are not valid for long-term prediction of the pendulum. In this paper,…

49 CFR 572.183 - Neck assembly.

Code of Federal Regulations, 2010 CFR

2010-10-01

... subpart E pendulum test fixture as shown in Figure U2-A in appendix A to this subpart, so that the... pendulum longitudinal centerline shown in Figure U2-A. Torque the half-spherical screws (175-2004) located... equivalent; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact...

49 CFR 572.35 - Limbs.

Code of Federal Regulations, 2011 CFR

2011-10-01

... in accordance with paragraph (b)(2) of this section, at 6.9 ft/sec ±0.10 ft/sec by the pendulum defined in § 572.36(b), the peak knee impact force, which is a product of pendulum mass and acceleration... the femur load cell simulator. (v) Guide the pendulum so that there is no significant lateral...

The Doppler Pendulum Experiment

ERIC Educational Resources Information Center

Lee, C. K.; Wong, H. K.

2011-01-01

An experiment to verify the Doppler effect of sound waves is described. An ultrasonic source is mounted at the end of a simple pendulum. As the pendulum swings, the rapid change of frequency can be recorded by a stationary receiver using a simple frequency-to-voltage converter. The experimental results are in close agreement with the Doppler…

49 CFR 572.183 - Neck assembly.

Code of Federal Regulations, 2011 CFR

2011-10-01

... subpart E pendulum test fixture as shown in Figure U2-A in appendix A to this subpart, so that the... pendulum longitudinal centerline shown in Figure U2-A. Torque the half-spherical screws (175-2004) located... equivalent; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact...

Steady States of the Parametric Rotator and Pendulum

ERIC Educational Resources Information Center

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…

49 CFR 572.35 - Limbs.

Code of Federal Regulations, 2010 CFR

2010-10-01

... in accordance with paragraph (b)(2) of this section, at 6.9 ft/sec ±0.10 ft/sec by the pendulum defined in § 572.36(b), the peak knee impact force, which is a product of pendulum mass and acceleration... the femur load cell simulator. (v) Guide the pendulum so that there is no significant lateral...

49 CFR 572.33 - Neck.

Code of Federal Regulations, 2014 CFR

2014-10-01

... (b) of this section, on a rigid pendulum as shown in Figure 22 so that the head's midsagittal plane is vertical and coincides with the plane of motion of the pendulum's longitudinal axis. ER02JN11.011 (4) Release the pendulum and allow it to fall freely from a height such that the tangential velocity...

49 CFR 572.183 - Neck assembly.

Code of Federal Regulations, 2014 CFR

2014-10-01

... subpart E pendulum test fixture as shown in Figure U2-A in appendix A to this subpart, so that the... pendulum longitudinal centerline shown in Figure U2-A. Torque the half-spherical screws (175-2004) located... equivalent; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact...

A Simple, Low-Cost, Data-Logging Pendulum Built from a Computer Mouse

ERIC Educational Resources Information Center

Gintautas, Vadas; Hubler, Alfred

2009-01-01

Lessons and homework problems involving a pendulum are often a big part of introductory physics classes and laboratory courses from high school to undergraduate levels. Although laboratory equipment for pendulum experiments is commercially available, it is often expensive and may not be affordable for teachers on fixed budgets, particularly in…

The Reproduction of Scientific Understanding about Pendulum Motion in the Public

ERIC Educational Resources Information Center

Manabu, Sumida

2004-01-01

This paper describes life-span development of understanding about pendulum motion and effects of school science. The subjects were 2,766 people ranging from kindergartners up to 88 years senior citizens. The conflict and consensus between children and their parent's understanding of pendulum motion were also analyzed. The kindergartner's…

The Multiple Pendulum Problem via Maple[R

ERIC Educational Resources Information Center

Salisbury, K. L.; Knight, D. G.

2002-01-01

The way in which computer algebra systems, such as Maple, have made the study of physical problems of some considerable complexity accessible to mathematicians and scientists with modest computational skills is illustrated by solving the multiple pendulum problem. A solution is obtained for four pendulums with no restriction on the size of the…

Idealisation and Galileo's Pendulum Discoveries: Historical, Philosophical and Pedagogical Considerations

ERIC Educational Resources Information Center

Matthews, Michael R.

2004-01-01

Galileo's discovery of the properties of pendulum motion depended on his adoption of the novel methodology of idealisation. Galileo's laws of pendulum motion could not be accepted until the empiricist methodological constraints placed on science by Aristotle, and by common sense, were overturned. As long as scientific claims were judged by how the…

Human Subject Effects on Torsion Pendulum Oscillations: Further Evidence of Mediation by Convection Currents.

PubMed

Hammerschlag, Richard; Linda Baldwin, Ann; Schwartz, Gary E

When a human subject sits beneath a wire mesh, hemispheric torsion pendulum (TP) a rapid-onset series of oscillations at frequencies both higher and lower than the fundamental frequency of the TP have been consistently observed. This study was designed to replicate and extend prior findings that suggest the human subject effect on TP behavior is due to subject-generated, heat-induced convection currents. Effects on pendulum behavior were tested after draping an aluminized "space blanket" over the subject and by replacing the subject with a thermal mattress pad shaped to approximate the human form. Experiments were performed in a basic science university research laboratory. Real-time recordings and Fast Fourier Transform frequency spectra of pendulum oscillatory movement. The space blanket blocked, while the mattress pad mimicked, the human subject induced complex array of pendulum oscillations. Our findings support and strengthen previous results that suggest the effects of human subjects on behavior of a torsion pendulum are mediated by body-heat-induced air convection rather than an unknown type of biofield. Copyright © 2016 Elsevier Inc. All rights reserved.

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagao, N.; Yokota, S.; Komurasaki, K.

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors (axial and horizontal (transverse) direction thrusts) of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%)more » in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of {+-}2.3 deg. was measured with the error of {+-}0.2 deg. under the typical operating conditions for the thruster.« less

Analytical study of the critical behavior of the nonlinear pendulum

NASA Astrophysics Data System (ADS)

Lima, F. M. S.

2010-11-01

The dynamics of a simple pendulum consisting of a small bob and a massless rigid rod has three possible regimes depending on its total energy E: Oscillatory (when E is not enough for the pendulum to reach the top position), "perpetual ascent" when E is exactly the energy needed to reach the top, and nonoscillatory for greater energies. In the latter regime, the pendulum rotates periodically without velocity inversions. In contrast to the oscillatory regime, for which an exact analytic solution is known, the other two regimes are usually studied by solving the equation of motion numerically. By applying conservation of energy, I derive exact analytical solutions to both the perpetual ascent and nonoscillatory regimes and an exact expression for the pendulum period in the nonoscillatory regime. Based on Cromer's approximation for the large-angle pendulum period, I find a simple approximate expression for the decrease of the period with the initial velocity in the nonoscillatory regime, valid near the critical velocity. This expression is used to study the critical slowing down, which is observed near the transition between the oscillatory and nonoscillatory regimes.

Characteristic Features of Hanging: A Study in Rural District of Central India.

PubMed

Ambade, Vipul Namdeorao; Kolpe, Dayanand; Tumram, Nilesh; Meshram, Satin; Pawar, Mohan; Kukde, Hemant

2015-09-01

The ligature mark is the most relevant feature of hanging. This study was undertaken with a view to determine the characteristic features of hanging and its association with ligature material or mode of suspension. Of a total medicolegal deaths reported at an Apex Medical Centre, hanging was noted in 4.1% cases, all suicidal with mortality rate of 1.5 per 100,000 population per year. The hanging was complete in 67.7% with nylon rope as the commonest type of ligature material used for ligation. The hanging mark was usually single, situated above thyroid cartilage, incomplete, prominent, and directed toward nape of neck. The mark of dribbling of saliva was seen in 11.8% cases. Facial congestion, petechial hemorrhage, and cyanosis were significantly seen in partial hanging. Though occasionally reported, the argent line was noted in 78.7% hanging deaths with neck muscle hemorrhage in 23.6% cases. Fracture of neck structure was predominant in complete hanging. © 2015 American Academy of Forensic Sciences.

Note: A 1-m Foucault pendulum rolling on a ball.

PubMed

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.

Comparison of strain rates of dart impacted plaques and pendulum impacted bumpers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scammell, K.L.

1987-01-01

The difference in strain rates prevailing during pendulum impact of bumpers versus high speed dart impact of plaques was investigated. Uni-axial strain gages were applied to the tension side of the plaques and bumpers directly opposite the point of impact. The plaques were impacted with an instrumented high rate dart impact tester and the bumpers impacted with a full scale bumper pendulum impact tester. Theoretical calculations and actual strain rate data support the conclusion that the strain rate of a plaque during dart impact significantly exceeds that of bumper strain rate during pendulum impact.

Hang cleans and hang snatches produce similar improvements in female collegiate athletes

PubMed Central

Ayers, JL; DeBeliso, M; Sevene, TG

2016-01-01

Olympic weightlifting movements and their variations are believed to be among the most effective ways to improve power, strength, and speed in athletes. This study investigated the effects of two Olympic weightlifting variations (hang cleans and hang snatches), on power (vertical jump height), strength (1RM back squat), and speed (40-yard sprint) in female collegiate athletes. 23 NCAA Division I female athletes were randomly assigned to either a hang clean group or hang snatch group. Athletes participated in two workout sessions a week for six weeks, performing either hang cleans or hang snatches for five sets of three repetitions with a load of 80-85% 1RM, concurrent with their existing, season-specific, resistance training program. Vertical jump height, 1RM back squat, and 40-yard sprint all had a significant, positive improvement from pre-training to post-training in both groups (p≤0.01). However, when comparing the gain scores between groups, there was no significant difference between the hang clean and hang snatch groups for any of the three dependent variables (i.e., vertical jump height, p=0.46; 1RM back squat, p=0.20; and 40-yard sprint, p=0.46). Short-term training emphasizing hang cleans or hang snatches produced similar improvements in power, strength, and speed in female collegiate athletes. This provides strength and conditioning professionals with two viable programmatic options in athletic-based exercises to improve power, strength, and speed. PMID:27601779

Duodenoscope hang time does not correlate with risk of bacterial contamination.

PubMed

Heroux, Riley; Sheppard, Michelle; Wright, Sharon B; Sawhney, Mandeep; Hirsch, Elizabeth B; Kalaidjian, Robin; Snyder, Graham M

2017-04-01

Current professional guidelines recommend a maximum hang time for reprocessed duodenoscopes of 5-14 days. We sought to study the association between hang time and risk of duodenoscope contamination. We analyzed cultures of the elevator mechanism and working channel collected in a highly standardized fashion just before duodenoscope use. Hang time was calculated as the time from reprocessing to duodenoscope sampling. The relationship between hang time and duodenoscope contamination was estimated using a calculated correlation coefficient between hang time in days and degree of contamination on the elevator mechanism and working channel. The 18 study duodenoscopes were cultured 531 times, including 465 (87.6%) in the analysis dataset. Hang time ranged from 0.07-39.93 days, including 34 (7.3%) with hang time ≥7.00 days. Twelve cultures (2.6%) demonstrated elevator mechanism and/or working channel contamination. The correlation coefficients for hang time and degree of duodenoscope contamination were very small and not statistically significant (-0.0090 [P = .85] for elevator mechanism and -0.0002 [P = 1.00] for working channel). Odds ratios for hang time (dichotomized at ≥7.00 days) and elevator mechanism and/or working channel contamination were not significant. We did not find a significant association between hang time and risk of duodenoscope contamination. Future guidelines should consider a recommendation of no limit for hang time. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Hang cleans and hang snatches produce similar improvements in female collegiate athletes.

PubMed

Ayers, J L; DeBeliso, M; Sevene, T G; Adams, K J

2016-09-01

Olympic weightlifting movements and their variations are believed to be among the most effective ways to improve power, strength, and speed in athletes. This study investigated the effects of two Olympic weightlifting variations (hang cleans and hang snatches), on power (vertical jump height), strength (1RM back squat), and speed (40-yard sprint) in female collegiate athletes. 23 NCAA Division I female athletes were randomly assigned to either a hang clean group or hang snatch group. Athletes participated in two workout sessions a week for six weeks, performing either hang cleans or hang snatches for five sets of three repetitions with a load of 80-85% 1RM, concurrent with their existing, season-specific, resistance training program. Vertical jump height, 1RM back squat, and 40-yard sprint all had a significant, positive improvement from pre-training to post-training in both groups (p≤0.01). However, when comparing the gain scores between groups, there was no significant difference between the hang clean and hang snatch groups for any of the three dependent variables (i.e., vertical jump height, p=0.46; 1RM back squat, p=0.20; and 40-yard sprint, p=0.46). Short-term training emphasizing hang cleans or hang snatches produced similar improvements in power, strength, and speed in female collegiate athletes. This provides strength and conditioning professionals with two viable programmatic options in athletic-based exercises to improve power, strength, and speed.

A Comprehensive Analytical Solution of the Nonlinear Pendulum

ERIC Educational Resources Information Center

Ochs, Karlheinz

2011-01-01

In this paper, an analytical solution for the differential equation of the simple but nonlinear pendulum is derived. This solution is valid for any time and is not limited to any special initial instance or initial values. Moreover, this solution holds if the pendulum swings over or not. The method of approach is based on Jacobi elliptic functions…

49 CFR 581.5 - Requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... the damage criteria of §§ 581.5(c)(1) through 581.5(c)(9) when impacted by a pendulum-type test device... of 1.5 m.p.h., and when impacted by a pendulum-type test device in accordance with the procedures of... original contours 30 minutes after completion of each pendulum and barrier impact, except where such damage...

49 CFR 581.5 - Requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... the damage criteria of §§ 581.5(c)(1) through 581.5(c)(9) when impacted by a pendulum-type test device... of 1.5 m.p.h., and when impacted by a pendulum-type test device in accordance with the procedures of... original contours 30 minutes after completion of each pendulum and barrier impact, except where such damage...

Oscillations of a Simple Pendulum with Extremely Large Amplitudes

ERIC Educational Resources Information Center

Butikov, Eugene I.

2012-01-01

Large oscillations of a simple rigid pendulum with amplitudes close to 180[degrees] are treated on the basis of a physically justified approach in which the cycle of oscillation is divided into several stages. The major part of the almost closed circular path of the pendulum is approximated by the limiting motion, while the motion in the vicinity…

49 CFR 581.5 - Requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... the damage criteria of §§ 581.5(c)(1) through 581.5(c)(9) when impacted by a pendulum-type test device... of 1.5 m.p.h., and when impacted by a pendulum-type test device in accordance with the procedures of... original contours 30 minutes after completion of each pendulum and barrier impact, except where such damage...

Measurement of Gravitational Acceleration Using a Computer Microphone Port

ERIC Educational Resources Information Center

Khairurrijal; Eko Widiatmoko; Srigutomo, Wahyu; Kurniasih, Neny

2012-01-01

A method has been developed to measure the swing period of a simple pendulum automatically. The pendulum position is converted into a signal frequency by employing a simple electronic circuit that detects the intensity of infrared light reflected by the pendulum. The signal produced by the electronic circuit is sent to the microphone port and…

Einstein versus the Simple Pendulum Formula: Does Gravity Slow All Clocks?

ERIC Educational Resources Information Center

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…

Maple[R] Version of the "Indian Rope Trick". Classroom Notes

ERIC Educational Resources Information Center

Knight, D. G.

2004-01-01

If the point of suspension of a multiple pendulum is suitably oscillated then the pendulum can remain in motion in an upside-down position. Since such pendulums can model flexible materials, this inverted motion is sometimes referred to as an 'Indian rope trick'. Despite the complexity of the governing differential equations, this rope trick can…

A Laboratory Experiment on Coupled Non-Identical Pendulums

ERIC Educational Resources Information Center

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…

49 CFR 581.5 - Requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the damage criteria of §§ 581.5(c)(1) through 581.5(c)(9) when impacted by a pendulum-type test device... of 1.5 m.p.h., and when impacted by a pendulum-type test device in accordance with the procedures of... original contours 30 minutes after completion of each pendulum and barrier impact, except where such damage...

49 CFR 581.5 - Requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... the damage criteria of §§ 581.5(c)(1) through 581.5(c)(9) when impacted by a pendulum-type test device... of 1.5 m.p.h., and when impacted by a pendulum-type test device in accordance with the procedures of... original contours 30 minutes after completion of each pendulum and barrier impact, except where such damage...

An Apparatus to Demonstrate Linear and Nonlinear Oscillations of a Pendulum

ERIC Educational Resources Information Center

Mayer, V. V.; Varaksina, E. I.

2016-01-01

A physical pendulum with a magnetic load is proposed for comparison of linear and nonlinear oscillations. The magnetic load is repelled by permanent magnets which are disposed symmetrically relative to the load. It is established that positions of the pendulum and the magnets determine the dependence of restoring force on displacement of the load.…

Chemistry and the Pendulum--What Have They to Do with Each Other?

ERIC Educational Resources Information Center

De Berg, K. C.

2006-01-01

Physicists have known for some time that pendulum motion is a useful analogy for other physical processes. Chemists have played with the idea from time to time but the strength of the analogy between pendulum motion and chemical processes has only received prominent published recognition since about 1980, although there are details of the analogy…

Extending the Range for Force Calibration in Magnetic Tweezers

PubMed Central

Daldrop, Peter; Brutzer, Hergen; Huhle, Alexander; Kauert, Dominik J.; Seidel, Ralf

2015-01-01

Magnetic tweezers are a wide-spread tool used to study the mechanics and the function of a large variety of biomolecules and biomolecular machines. This tool uses a magnetic particle and a strong magnetic field gradient to apply defined forces to the molecule of interest. Forces are typically quantified by analyzing the lateral fluctuations of the biomolecule-tethered particle in the direction perpendicular to the applied force. Since the magnetic field pins the anisotropy axis of the particle, the lateral fluctuations follow the geometry of a pendulum with a short pendulum length along and a long pendulum length perpendicular to the field lines. Typically, the short pendulum geometry is used for force calibration by power-spectral-density (PSD) analysis, because the movement of the bead in this direction can be approximated by a simple translational motion. Here, we provide a detailed analysis of the fluctuations according to the long pendulum geometry and show that for this direction, both the translational and the rotational motions of the particle have to be considered. We provide analytical formulas for the PSD of this coupled system that agree well with PSDs obtained in experiments and simulations and that finally allow a faithful quantification of the magnetic force for the long pendulum geometry. We furthermore demonstrate that this methodology allows the calibration of much larger forces than the short pendulum geometry in a tether-length-dependent manner. In addition, the accuracy of determination of the absolute force is improved. Our force calibration based on the long pendulum geometry will facilitate high-resolution magnetic-tweezers experiments that rely on short molecules and large forces, as well as highly parallelized measurements that use low frame rates. PMID:25992733

Oscillators: Old and new perspectives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattacharjee, Jayanta K.; Roy, Jyotirmoy

We consider some of the well known oscillators in literature which are known to exhibit interesting effects of nonlinearity. We review the Lindstedt-Poincare technique for dealing with with the nonlinear effects and then go on to introduce the relevance of the renormalization group for the oscillator following the pioneering work of Chen et al. It is pointed out that the traditional Lindstedt-Poincare and the renormalization group techniques have operational connections. We use this to find an unexpected mode softening in the double pendulum. This mode softening prompted us to look for chaos in the double pendulum at low energies-energies thatmore » are just sufficient to allow the outer pendulum to rotate (the double pendulum is known to be chaotic at high energies-energies that are greater than that needed to make both pendulums to rotate). The emergence of the chaos is strongly dependent on initial conditions.« less

Efficiency of SparkJet

NASA Technical Reports Server (NTRS)

Golbabaei-Asl, M.; Knight, D.; Wilkinson, S.

2013-01-01

The thermal efficiency of a SparkJet is evaluated by measuring the impulse response of a pendulum subject to a single spark discharge. The SparkJet is attached to the end of a pendulum. A laser displacement sensor is used to measure the displacement of the pendulum upon discharge. The pendulum motion is a function of the fraction of the discharge energy that is channeled into the heating of the gas (i.e., increasing the translational-rotational temperature). A theoretical perfect gas model is used to estimate the portion of the energy from the heated gas that results in equivalent pendulum displacement as in the experiment. The earlier results from multiple runs for different capacitances of C = 3, 5, 10, 20, and 40(micro)F demonstrate that the thermal efficiency decreases with higher capacitive discharges.1 In the current paper, results from additional run cases have been included and confirm the previous results

Dynamics of generalized sine-Gordon soliton in inhomogeneous media

NASA Astrophysics Data System (ADS)

Gharaati, A.; Khordad, R.

2011-03-01

In this paper we introduce a few novel generalized sine-Gordon equations and study the dynamics of its solitons in inhomogeneous media. We consider length, mass, gravitational acceleration and spring stiffness of a coupled pendulums chain as a function of position x. Then in the continuum limit we derive semi-analytical and numerical soliton solutions of the modified sine-Gordon equation in the inhomogeneous media. The obtained results confirm that the behavior of solitons in these media is similar to that of a classical point particle moved in an external potential.

Study of endolaryngeal structures by videolaryngoscopy after hanging: a new approach to understanding the physiopathogenesis.

PubMed

Duband, S; Timoshenko, A P; Mohammedi, R; Prades, J-M; Barral, F-G; Debout, M; Péoc'h, M

2009-11-20

To evaluate laryngoscopic findings in hanging cases and to compare them with magnetic resonance imaging (MRI) and forensic autopsy results. Postmortem nasolaryngofibroscopy and MRI of five people who died from hanging were performed. Three people who died from other causes than hanging were also examined with a flexible laryngofibroscope. The results were compared with injuries discovered during forensic autopsy. In all five hanging cases, laryngofibroscopic investigation showed a vocal fold position in complete adduction confirmed by MRI. This position did not seem to be influenced by the intensity of the forces applied to neck or postmortem delay and cadaveric phenomena. The vocal cords of the three non-hanging deceased were found in the intermediate position. These findings could suggest that pressure applied to the cervical nervous and cartilaginous structures or their elongation during hanging could lead to closure of the glottis with vocal cord adduction maintained after death. Laryngofibroscopic examination in hanging cases could be very useful in confirming the vital character of the hanging and understanding asphyxial phenomena in incomplete suspension without laryngeal crush.

The Pendulum in the 21st Century-Relic or Trendsetter

ERIC Educational Resources Information Center

Peters, Randall D.

2004-01-01

When identifying instruments that have had great influence on the history of physics, none comes to mind more quickly than the pendulum. Though first treated scientifically by Galileo in the 16th century, and in some respects nearly "dead" by the middle of the 20th century; the pendulum experienced "rebirth" by becoming an archetype of chaos. With…

Analysis of Pendulum Period with an iPod Touch/iPhone

ERIC Educational Resources Information Center

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.…

On the Stable Limit Cycle of a Weight-Driven Pendulum Clock

ERIC Educational Resources Information Center

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…

49 CFR 572.187 - Lumbar spine.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-headform assembly to the Part 572 pendulum test fixture per procedure in § 572.183(b)(2) and as shown in... assembly (175-5506) to 50 ±5 in-lb; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact velocity of 6.05 ±0.1 m/s measured at the center of the pendulum...

49 CFR 572.187 - Lumbar spine.

Code of Federal Regulations, 2012 CFR

2012-10-01

...-headform assembly to the Part 572 pendulum test fixture per procedure in § 572.183(b)(2) and as shown in... assembly (175-5506) to 50 ±5 in-lb; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact velocity of 6.05 ±0.1 m/s measured at the center of the pendulum...

49 CFR 572.187 - Lumbar spine.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-headform assembly to the Part 572 pendulum test fixture per procedure in § 572.183(b)(2) and as shown in... assembly (175-5506) to 50 ± 5 in-lb; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact velocity of 6.05 ±0.1 m/s measured at the center of the pendulum...

The Bravais Pendulum: The Distinct Charm of an Almost Forgotten Experiment

ERIC Educational Resources Information Center

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…

49 CFR 572.187 - Lumbar spine.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-headform assembly to the Part 572 pendulum test fixture per procedure in § 572.183(b)(2) and as shown in... assembly (175-5506) to 50 ± 5 in-lb; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact velocity of 6.05 ±0.1 m/s measured at the center of the pendulum...

Approximate Expressions for the Period of a Simple Pendulum Using a Taylor Series Expansion

ERIC Educational Resources Information Center

Belendez, Augusto; Arribas, Enrique; Marquez, Andres; Ortuno, Manuel; Gallego, Sergi

2011-01-01

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…

49 CFR 572.187 - Lumbar spine.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-headform assembly to the Part 572 pendulum test fixture per procedure in § 572.183(b)(2) and as shown in... assembly (175-5506) to 50 ±5 in-lb; (3) Release the pendulum from a height sufficient to allow it to fall freely to achieve an impact velocity of 6.05 ±0.1 m/s measured at the center of the pendulum...

Experimental Uncertainty Associated with Traveling Wave Excitation

DTIC Science & Technology

2014-09-15

20 2.9 Schematic of the Lumped Model [6] . . . . . . . . . . . . . . . . . . . . . . . 21 2.10 Multiple Coupled Pendulum [7...model to describe the physical system, the authors chose to employ a coupled pendulum model to represent a rotor. This system is shown in Figure 2.10...System mistuning is introduced by altering pendulum lengths. All other system parameters are equal. A linear viscous proportional damping force is

Working Model of a Foucault Pendulum at Intermediate Latitudes

ERIC Educational Resources Information Center

Sears, Francis W.

1969-01-01

Describes a working model of a Foucault pendulum at intermediate latitudes constructed of a steel drill rod with a steel ball attached at one end. The rod makes an angle of 45 degrees with the rotation axis of a horizontal turntable. The vibrating system is the same as that which led Foucault to construct his first gravity pendulum. (LC)

Propagation-invariant beams with quantum pendulum spectra: from Bessel beams to Gaussian beam-beams.

PubMed

Dennis, Mark R; Ring, James D

2013-09-01

We describe a new class of propagation-invariant light beams with Fourier transform given by an eigenfunction of the quantum mechanical pendulum. These beams, whose spectra (restricted to a circle) are doubly periodic Mathieu functions in azimuth, depend on a field strength parameter. When the parameter is zero, pendulum beams are Bessel beams, and as the parameter approaches infinity, they resemble transversely propagating one-dimensional Gaussian wave packets (Gaussian beam-beams). Pendulum beams are the eigenfunctions of an operator that interpolates between the squared angular momentum operator and the linear momentum operator. The analysis reveals connections with Mathieu beams, and insight into the paraxial approximation.

Analysis of the linearity of half periods of the Lorentz pendulum

NASA Astrophysics Data System (ADS)

Wickramasinghe, T.; Ochoa, R.

2005-05-01

We analyze the motion of the Lorentz pendulum, a simple pendulum whose length is changed at a constant rate k. We show both analytically and numerically that the half period Tn, the time between half oscillations as measured from midpoint to midpoint, increases linearly with the oscillation number n such that Tn+1-Tn≈kπ2/2g, where g is the acceleration due to gravity. A video camera is used to record the motion of the oscillating bob of the pendulum and verify the linearity of Tn with oscillation number. The theory and the experiment are suitable for an advanced undergraduate laboratory.

An inexpensive, multipurpose physical pendulum

NASA Astrophysics Data System (ADS)

Schultz, David

2012-10-01

The pendulum is a highly versatile tool for teaching physics. Many special purpose pendula for student experiments have been described.1-4 In this paper, I describe an inexpensive, multipurpose physical pendulum that can function as both a variable gravity and ballistic pendulum. I designed the apparatus for use in a rotational dynamics unit of the AP Physics C mechanics course. The use of a bike wheel hub pivot allows for low-friction, rugged operation that yields results commensurate with those obtained with much more expensive pendula available on the market (typically 500 per unit5), placing these types of experiments within reach of the teacher on a restricted budget.

Orion GN&C Detection and Mitigation of Parachute Pendulosity

NASA Technical Reports Server (NTRS)

Kane, Mark A.; Wacker, Roger

2016-01-01

New techniques being employed by Orion guidance, navigation, and control (GN&C) using a reaction control system (RCS) under parachutes are described. Pendulosity refers to a pendulum-oscillatory mode that can occur during descent under main parachutes and that has been observed during Orion parachute drop tests. The pendulum mode reduces the ability of GN&C to maneuver the suspended vehicle resulting in undesirable increases to structural loads at touchdown. Parachute redesign efforts have been unsuccessful in reducing the pendulous behavior necessitating GN&C mitigation options. An observer has been developed to estimate the pendulum motion as well as the underlying wind velocity vector. Using this knowledge, the control system maneuvers the vehicle using two separate strategies determined by wind velocity magnitude and pendulum energy thresholds; at high wind velocities the vehicle is aligned with the wind direction and for cases with lower wind velocities and large pendulum amplitudes the vehicle is aligned such that it is perpendicular to the swing plane. Pendulum damping techniques using RCS thrusters are discussed but have not been selected for use onboard the Orion spacecraft. The techniques discussed in this paper will be flown on Exploration Mission 1 (EM-1).

Pendulum Motion in Main Parachute Clusters

NASA Technical Reports Server (NTRS)

Ray, Eric S.; Machin, Ricardo A.

2015-01-01

The coupled dynamics of a cluster of parachutes to a payload are notoriously difficult to predict. Often the payload is designed to be insensitive to the range of attitude and rates that might occur, but spacecraft generally do not have the mass and volume budgeted for this robust of a design. The National Aeronautics and Space Administration (NASA) Orion Capsule Parachute Assembly System (CPAS) implements a cluster of three mains for landing. During testing of the Engineering Development Unit (EDU) design, it was discovered that with a cluster of two mains (a fault tolerance required for human rating) the capsule coupled to the parachute cluster could get into a limit cycle pendulum motion which would exceed the spacecraft landing capability. This pendulum phenomenon could not be predicted with the existing models and simulations. A three phased effort has been undertaken to understand the consequence of the pendulum motion observed, and explore potential design changes that would mitigate this phenomenon. This paper will review the early analysis that was performed of the pendulum motion observed during EDU testing, summarize the analysis ongoing to understand the root cause of the pendulum phenomenon, and discuss the modeling and testing that is being pursued to identify design changes that would mitigate the risk.

World pendulum—a distributed remotely controlled laboratory (RCL) to measure the Earth's gravitational acceleration depending on geographical latitude

NASA Astrophysics Data System (ADS)

Gröber, S.; Vetter, M.; Eckert, B.; Jodl, H.-J.

2007-05-01

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(phiv), that the Earth's effective gravitational acceleration g depends on the angle of latitude phiv. Then, we present all necessary formula to deduce g(phiv) 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(phiv) 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.

Outcomes of therapeutic hypothermia in unconscious patients after near-hanging.

PubMed

Lee, Byung Kook; Jeung, Kyung Woon; Lee, Hyoung Youn; Lim, Jae Hoon

2012-09-01

Hanging has been increasingly used to commit suicide. There is no specific treatment besides general intensive care after near-hanging. Therapeutic hypothermia (TH) has been used in unconscious patients after near-hanging. To describe the outcomes in unconscious patients after near-hanging in order to determine whether TH improves the outcome of near-hanging injury. Medical charts were reviewed of unconscious patients after near-hanging who presented to Chonnam National University Hospital between January 2006 and December 2010 and who were considered to be eligible for TH. According to local policy, unconscious survivors after near-hanging, whether or not they experienced cardiac arrest at the scene, were treated with TH if this was agreed by next-of-kin. There were 16 survivors of asphyxial cardiac arrest after near-hanging, of whom 13 received TH. Among them, only one (7.7%, 95% CI 1.4% to 33.3%) attained Cerebral Performance Category (CPC) 1; the other 15 patients had poor neurological outcomes (CPC 5 in seven patients and CPC 4 in eight patients). Nine of the patients did not experience cardiac arrest at the scene and of these, four received TH and five received normothermic treatment. All patients who did not have cardiac arrest recovered and were discharged with CPC 1. In this study, outcomes in unconscious near-hanging patients with cardiac arrest were poor despite treatment with TH. Before recommending TH in near-hanging patients, a prospective, randomised controlled study is required.

Hanging Out with Which Friends? Friendship-Level Predictors of Unstructured and Unsupervised Socializing in Adolescence

PubMed Central

Siennick, Sonja E.; Osgood, D. Wayne

2012-01-01

Companions are central to explanations of the risky nature of unstructured and unsupervised socializing, yet we know little about whom adolescents are with when hanging out. We examine predictors of how often friendship dyads hang out via multilevel analyses of longitudinal friendship-level data on over 5,000 middle schoolers. Adolescents hang out most with their most available friends and their most generally similar friends, not with their most at-risk or similarly at-risk friends. These findings vary little by gender and wave. Together, the findings suggest that the risks of hanging out stem from the nature of hanging out as an activity, not the nature of adolescents’ companions, and that hanging out is a context for friends’ mutual reinforcement of pre-existing characteristics. PMID:23204811

Hanging Out with Which Friends? Friendship-Level Predictors of Unstructured and Unsupervised Socializing in Adolescence.

PubMed

Siennick, Sonja E; Osgood, D Wayne

2012-12-01

Companions are central to explanations of the risky nature of unstructured and unsupervised socializing, yet we know little about whom adolescents are with when hanging out. We examine predictors of how often friendship dyads hang out via multilevel analyses of longitudinal friendship-level data on over 5,000 middle schoolers. Adolescents hang out most with their most available friends and their most generally similar friends, not with their most at-risk or similarly at-risk friends. These findings vary little by gender and wave. Together, the findings suggest that the risks of hanging out stem from the nature of hanging out as an activity, not the nature of adolescents' companions, and that hanging out is a context for friends' mutual reinforcement of pre-existing characteristics.

29 CFR 1928.53 - Protective enclosures for wheel-type agricultural tractors-test procedures and performance...

Code of Federal Regulations, 2013 CFR

2013-07-01

... accomplished by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... of the pendulum will swing, or alternatively, two sets of symmetrically located cables may be used at... from the rear, followed by a load to the side on the same enclosure structure. The pendulum swinging...

An Approximate Solution to the Equation of Motion for Large-Angle Oscillations of the Simple Pendulum with Initial Velocity

ERIC Educational Resources Information Center

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…

29 CFR 1928.53 - Protective enclosures for wheel-type agricultural tractors-test procedures and performance...

Code of Federal Regulations, 2010 CFR

2010-07-01

... accomplished by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... of the pendulum will swing, or alternatively, two sets of symmetrically located cables may be used at... from the rear, followed by a load to the side on the same enclosure structure. The pendulum swinging...

Fluid-Structure Interaction in a Fluid-Filled Composite Structure Subjected to Low Velocity Impact

DTIC Science & Technology

2016-06-01

for creating an E-glass composite cubic structure and a pendulum was designed and built to provide a repeatable low velocity impact. The behavior of...structure and a pendulum was designed and built to provide a repeatable low velocity impact. The behavior of the composite structure was studied at various...SET-UP .......................................................31  1.  Impact Pendulum

29 CFR 1928.53 - Protective enclosures for wheel-type agricultural tractors-test procedures and performance...

Code of Federal Regulations, 2014 CFR

2014-07-01

...,000-kg) weight acting as a pendulum. The impact face of the weight shall be 27 ±1 in. by 27 ±1 in... restraining cables shall be located in the plane in which the center of gravity of the pendulum will swing, or... side on the same enclosure structure. The pendulum swinging from the height determined by paragraph (d...

World Pendulum--A Distributed Remotely Controlled Laboratory (RCL) to Measure the Earth's Gravitational Acceleration Depending on Geographical Latitude

ERIC Educational Resources Information Center

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…

29 CFR 1928.53 - Protective enclosures for wheel-type agricultural tractors-test procedures and performance...

Code of Federal Regulations, 2012 CFR

2012-07-01

... accomplished by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... of the pendulum will swing, or alternatively, two sets of symmetrically located cables may be used at... from the rear, followed by a load to the side on the same enclosure structure. The pendulum swinging...

29 CFR 1928.53 - Protective enclosures for wheel-type agricultural tractors-test procedures and performance...

Code of Federal Regulations, 2011 CFR

2011-07-01

... accomplished by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... of the pendulum will swing, or alternatively, two sets of symmetrically located cables may be used at... from the rear, followed by a load to the side on the same enclosure structure. The pendulum swinging...

Accidental hanging by a T-shirt collar in a man with morphine intoxication: an unusual case.

PubMed

Kodikara, Sarathchandra; Alagiyawanna, Ramesh

2011-09-01

Accidental hanging is rare across all age groups, and it is even rarer in the adult population except in autoerotic asphyxia. Few cases have been reported in the literature, which describe unusual patterns of accidental hanging. This article focuses on an unusual pattern of accidental hanging of a 25-year-old man, who was in a state of morphine-induced central nervous system depression and found dead in a sitting position with the collar of his T-shirt hanging off a jutting-out root of a tree. The hanged collar acted as a ligature compressing the neck.

Retrospective analysis of 319 hanging and strangulation cases between 2001 and 2014 in Shanghai.

PubMed

Ma, Jianlong; Jing, Haojia; Zeng, Yan; Tao, Li; Yang, Yulei; Ma, Kaijun; Chen, Long

2016-08-01

In this study, we retrospectively analyzed 141 cases of hanging and 178 cases of ligature strangulation recorded in the Shanghai Municipal Public Security Bureau between January 2001 and December 2014 to explore the characteristics of hanging and ligature strangulation and to supply a scientific reference for forensic pathology. Several significant differences between hanging and ligature strangulation were found. Hanging cases were mostly suicide, with some accidental cases. Strangulation cases were mostly homicide, with a few cases of suicide or sexual asphyxia. Male hanging was more common than female hanging, with a ratio of 5:2. However, there were more female than male strangulation cases, with a ratio of 13:5. The ligature marks in hanging cases were almost all of a "U" type and above the hyoid bone. The ligature marks in strangulation cases were almost always a closed circle, but the position varied. The most common vital reactions were subcutaneous hemorrhage, exfoliation and blister, which are strong evidence of antemortem injury. Hemorrhagic spots were found on the temporalis, scalp, chest and back in strangulation cases, but were rare in hanging cases. Hemorrhagic manifestations were most common in the sternocleidomastoid muscle in hanging cases, and in the sternohyoid and sternothyroid muscles in strangulation cases. Fractures occurred in only ∼17% of victims. There are notable differences between hanging and ligature strangulation, which can help distinguish between these causes of death. These characteristics should be considered in forensic practice. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

An energy-optimal solution for transportation control of cranes with double pendulum dynamics: Design and experiments

NASA Astrophysics Data System (ADS)

Sun, Ning; Wu, Yiming; Chen, He; Fang, Yongchun

2018-03-01

Underactuated cranes play an important role in modern industry. Specifically, in most situations of practical applications, crane systems exhibit significant double pendulum characteristics, which makes the control problem quite challenging. Moreover, most existing planners/controllers obtained with standard methods/techniques for double pendulum cranes cannot minimize the energy consumption when fulfilling the transportation tasks. Therefore, from a practical perspective, this paper proposes an energy-optimal solution for transportation control of double pendulum cranes. By applying the presented approach, the transportation objective, including fast trolley positioning and swing elimination, is achieved with minimized energy consumption, and the residual oscillations are suppressed effectively with all the state constrains being satisfied during the entire transportation process. As far as we know, this is the first energy-optimal solution for transportation control of underactuated double pendulum cranes with various state and control constraints. Hardware experimental results are included to verify the effectiveness of the proposed approach, whose superior performance is reflected by being experimentally compared with some comparative controllers.

Measurement of Motion Transfer Functions for Mirror Suspensions

NASA Astrophysics Data System (ADS)

Stuver, Amber; Beilby, Mark; Glancy, Aran; Gonzalez, Gabriela

2001-04-01

Interferometric gravitational wave detectors, such as LIGO, use mirrors suspended in pendulums. The current LIGO dectors use simple pendulums, but advanced LIGO detectors will use multiple pendulums with some stages on soft vertical springs. A drawback of the a multiple pendulum design is that it is difficult to model and predict cross couplings from one vibrational mode to another due to slight unavoidable asymmetries in the real system. Of most concern are the couplings to motion along the optical axis and into angular motions, which have the most potential to contaminate data. Our research focuses on the experimental testing of the pendulum designs for cross couplings with a special dedicated shaking stage. The cross couplings in each degree of freedom, their isolation and damping are investigated in this research though the measurement of transfer functions as filtered though the suspension system. This research is supported by The Pennsylvania State University, the NSF Grant no. PHY-9870032, and the REU program at The Pennsylvania State University.

Proposal of a new electromechanical total artificial heart: the TAH Serpentina.

PubMed

Sauer, I M; Frank, J; Bücherl, E S

1999-03-01

A new type of energy converter for an electro-mechanical total artificial heart (TAH) based on the principle of a unidirectional moving motor is described. Named the TAH Serpentina, the concept consists of 2 major parts, a pendulum shaped movable element fixed on one side using a joint bearing and a special shaped drum cam. Pusher plates are mounted flexibly to the crossbar of the pendulum. A motor drives the special shaped drum cam linked to the pendulum through a ball bearing. The circular motion of the unidirectional moving brushless DC motor is transferred into the linear motion of the pendulum to drive the pusher plates. Using a crossbar with a variable length, the stroke of the pendulum and therefore the displaced blood volume is alterable. To achieve a variable length, an electric driven screw thread or a hydraulic system is possible. Comparable to the natural heart, cardiac output would be determined by frequency and stroke volume.

Idealisation and Galileo's Pendulum Discoveries: Historical, Philosophical and Pedagogical Considerations

NASA Astrophysics Data System (ADS)

Matthews, Michael R.

2004-11-01

Galileo's discovery of the properties of pendulum motion depended on his adoption of the novel methodology of idealisation. Galileo's laws of pendulum motion could not be accepted until the empiricist methodological constraints placed on science by Aristotle, and by common sense, were overturned. As long as scientific claims were judged by how the world was immediately seen to behave, and as long as mathematics and physics were kept separate, then Galileo's pendulum claims could not be substantiated; the evidence was against them. Proof of the laws required not just a new science, but a new way of doing science, a new way of handling evidence, a new methodology of science. This was Galileo's method of idealisatioin. It was the foundation of the Galilean-Newtonian Paradigm which characterised the Scientific Revolution of the 17th century, and the subsequent centuries of modern science. As the pendulum was central to Galileo's and Newton's physics, appreciating the role of idealisation in their work is an instructive way to learn about the nature of science.

Precessional switching of antiferromagnets by electric field induced Dzyaloshinskii-Moriya torque

NASA Astrophysics Data System (ADS)

Kim, T. H.; Grünberg, P.; Han, S. H.; Cho, B. K.

2018-05-01

Antiferromagnetic insulators (AFIs) have attracted much interest from many researchers as promising candidates for use in ultrafast, ultralow-dissipation spintronic devices. As a fast method of reversing magnetization, precessional switching is realized when antiferromagnetic Néel orders l =(s1+s2 )/2 surmount the magnetic anisotropy or potential barrier in a given magnetic system, which is described well by the antiferromagnetic plane pendulum (APP) model. Here, we report that, as an alternative switching scenario, the direct coupling of an electric field with Dzyaloshinskii-Moriya (DM) interaction, which stems from spin-orbit coupling, is exploited for optimal switching. We derive the pendulum equation of motion of antiferromagnets, where DM torque is induced by a pulsed electric field. The temporal DM interaction is found to not only be in the form of magnetic torques (e.g., spin-orbit torque or magnetic field) but also modifies the magnetic potential that limits l 's activity; as a result, appropriate controls (e.g., direction, magnitude, and pulse shape) of the induced DM vector realize deterministic reversal in APP. The results present an approach for the control of a magnetic storage device by means of an electric field.

Modeling and Model Identification of Autonomous Underwater Vehicles

DTIC Science & Technology

2015-06-01

setup, based on a quadrifilar pendulum , is developed to measure the moments of inertia of the vehicle. System identification techniques, based on...parametric models of the platforms: an individual channel excitation approach and a free decay pendulum test. The former is applied to THAUS, which can...excite the system in individual channels in four degrees of freedom. These results are verified in the free decay pendulum setup, which has the

29 CFR 1928.52 - Protective frames for wheel-type agricultural tractors-test procedures and performance requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be 27 ±1 in... restraining cables shall be located in the plane in which the center of gravity of the pendulum will swing, or... pendulum swinging from the height determined by paragraph (d)(3)(ii) of this section shall be used to...

29 CFR 1926.1002 - Protective frames (roll-over protective structures, known as ROPS) for wheel-type agricultural...

Code of Federal Regulations, 2012 CFR

2012-07-01

... produced by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... the center of gravity of the pendulum will swing, or more than one restraining cable shall give a... to the side on the same frame. The pendulum dropped from the height (see the definition of “H” in...

29 CFR 1926.1002 - Protective frames (roll-over protective structures, known as ROPS) for wheel-type agricultural...

Code of Federal Regulations, 2011 CFR

2011-07-01

... produced by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... the center of gravity of the pendulum will swing, or more than one restraining cable shall give a... to the side on the same frame. The pendulum dropped from the height (see the definition of “H” in...

29 CFR 1926.1002 - Protective frames (roll-over protective structures, known as ROPS) for wheel-type agricultural...

Code of Federal Regulations, 2010 CFR

2010-07-01

... produced by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... the center of gravity of the pendulum will swing, or more than one restraining cable shall give a... to the side on the same frame. The pendulum dropped from the height (see the definition of “H” in...

The experimental determination of the moments of inertia of airplanes by a simplified compound-pendulum method

NASA Technical Reports Server (NTRS)

Gracey, William

1948-01-01

A simplified compound-pendulum method for the experimental determination of the moments of inertia of airplanes about the x and y axes is described. The method is developed as a modification of the standard pendulum method reported previously in NACA report, NACA-467. A brief review of the older method is included to form a basis for discussion of the simplified method. (author)

29 CFR 1926.1002 - Protective frames (roll-over protective structures, known as ROPS) for wheel-type agricultural...

Code of Federal Regulations, 2013 CFR

2013-07-01

... produced by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... the center of gravity of the pendulum will swing, or more than one restraining cable shall give a... to the side on the same frame. The pendulum dropped from the height (see the definition of “H” in...

Theoretical Pressure Distribution, Apparent Mass, and Moment of Inertia of a Disk Pendulum Oscillating at Low Frequency. M.S. Thesis - George Washington Univ., Washington, D. C.

NASA Technical Reports Server (NTRS)

Dunning, R. S.

1973-01-01

Equations are developed which give the pressure profile, the forces and torques on a disk pendulum by means of point source wave theory from acoustics. The pressure, force and torque equations for an unbaffled disk are developed. These equations are then used to calculate the apparent mass and apparent inertia for the pendulum.

29 CFR 1926.1002 - Protective frames (roll-over protective structures, known as ROPS) for wheel-type agricultural...

Code of Federal Regulations, 2014 CFR

2014-07-01

... produced by using a 4,410-lb (2,000-kg) weight acting as a pendulum. The impact face of the weight shall be... the center of gravity of the pendulum will swing, or more than one restraining cable shall give a... to the side on the same frame. The pendulum dropped from the height (see the definition of “H” in...

A Clinically Realistic Large Animal Model of Intra-Articular Fracture

DTIC Science & Technology

2014-12-01

pendulum system for measuring energy absorption during fracture insult to large animal joints in vivo. J Biomech Eng. 2014 Jun;136(6):064502. PMID:24760051...Model 4. Yucatan Minipig 5. Impact 6. Pendulum 7. Mankin Scoring 8. Inflammatory Cytokines 9. Gait Analysis 10. Incongruity 3. OVERALL...primarily hardware upgrades and ex-vivo experimentation of the pendulum . 3.2.a Device Upgrades The primary hardware upgrade was to instrument the

Novel Out-Coupling Techniques for Terahertz Free Electron Lasers

DTIC Science & Technology

2012-06-01

4  1.   FEL “ Pendulum ” Equation and Electron Dynamics .......................4  2.   FEL...4 B. FEL THEORY 1. FEL “ Pendulum ” Equation and Electron Dynamics The dynamics of electron motion as it passes through the undulator are governed...I.5, then the FEL “ pendulum equation” is derived , (I.7) where is the dimensionless laser field amplitude[1]. From this, it is shown that changes

In full swing? How do pendulum migrant labourers in Vietnam adjust their sexual perspectives to their rural-urban lives?

PubMed

Nguyen, Huong Ngoc; Hardesty, Melissa; Hong, Khuat Thu

2011-11-01

Having emerged only recently due to fast urbanisation and globalisation, pendulum migrant labourers in Vietnam are economically, culturally and socially difficult to locate - though they are estimated to number in their millions. Defined by their frequent migration between village and city, pendulum migrant labourers occupy an extended period of liminality. Are they traditional villagers or liberal city people when it comes to sex? Does city life radically change their views on sexuality? Starting with the premise that living environments play a key role in structuring the practical and symbolic realities of sex, this paper explores how extended periods of circular migration between the village and city - living environments that differ markedly in terms of socioeconomic and cultural conditions - affect the sexual views and perspectives of Vietnamese pendulum migrant labourers. Analysis from in-depth interviews with 23 married pendulum migrant labourers revealed that even though they had been living the pendulum life for several years, they continued to identify themselves, sexually, as traditional villagers. Among labourers the link between sexuality and living environment was a matter of pragmatism - matching 'suitable' sexual behaviour to social, even if imagined, location - and of privilege or 'leagues' - matching behaviour and comportment to social pedigree.

Clinical Usefulness of the Pendulum Test Using a NK Table to Measure the Spasticity of Patients with Brain Lesions

PubMed Central

Kim, Yong-Wook

2013-01-01

. [Purpose] The purpose of the present study was to investigate the clinical usefulness (reliability and validity) of the pendulum test using a Noland-Kuckhoff (NK) table with an attached electrogoniometer to measure the spasticity of patients with brain lesions. [Subjects] The subjects were 31 patients with stroke or traumatic brain injury. [Methods] The intraclass correlation coefficient (ICC) was used to verify the test–retest reliability of spasticity measures obtained using the pendulum test. Pearson's product correlation coefficient was used to examine the validity of the pendulum test using the amplitude of the patellar tendon reflex (PTR) test, an objective and quantitative measure of spasticity. [Results] The test–retest reliability was high, reflecting a significant correlation between the test and the retest (ICCs = 0.95–0.97). A significant negative correlation was found between the amplitude of the PTR test and the four variables measured in the pendulum test (r = −0.77– −0.85). [Conclusion] The pendulum test using a NK table is an objective measure of spasticity and can be used in the clinical setting in place of more expensive and complicated equipment. Further studies are needed to investigate the therapeutic effect of this method on spasticity. PMID:24259775

Clinical usefulness of the pendulum test using a NK table to measure the spasticity of patients with brain lesions.

PubMed

Kim, Yong-Wook

2013-10-01

. [Purpose] The purpose of the present study was to investigate the clinical usefulness (reliability and validity) of the pendulum test using a Noland-Kuckhoff (NK) table with an attached electrogoniometer to measure the spasticity of patients with brain lesions. [Subjects] The subjects were 31 patients with stroke or traumatic brain injury. [Methods] The intraclass correlation coefficient (ICC) was used to verify the test-retest reliability of spasticity measures obtained using the pendulum test. Pearson's product correlation coefficient was used to examine the validity of the pendulum test using the amplitude of the patellar tendon reflex (PTR) test, an objective and quantitative measure of spasticity. [Results] The test-retest reliability was high, reflecting a significant correlation between the test and the retest (ICCs = 0.95-0.97). A significant negative correlation was found between the amplitude of the PTR test and the four variables measured in the pendulum test (r = -0.77- -0.85). [Conclusion] The pendulum test using a NK table is an objective measure of spasticity and can be used in the clinical setting in place of more expensive and complicated equipment. Further studies are needed to investigate the therapeutic effect of this method on spasticity.

Foucault pendulum with eddy-current damping of the elliptical motion

NASA Astrophysics Data System (ADS)

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.

Human balancing of an inverted pendulum: position control by small, ballistic-like, throw and catch movements

PubMed Central

Loram, Ian D; Lakie, Martin

2002-01-01

In standing, there are small sways of the body. Our interest is to use an artificial task to illuminate the mechanisms underlying the sways and to account for changes in their size. Using the ankle musculature, subjects balanced a large inverted pendulum. The equilibrium of the pendulum is unstable and quasi-regular sway was observed like that in quiet standing. By giving full attention to minimising sway subjects could systematically reduce pendulum movement. The pendulum position, the torque generated at each ankle and the soleus and tibialis anterior EMGs were recorded. Explanations about how the human inverted pendulum is balanced usually ignore the fact that balance is maintained over a range of angles and not just at one angle. Any resting equilibrium position of the pendulum is unstable and in practice temporary; movement to a different resting equilibrium position can only be accomplished by a biphasic ‘throw and catch’ pattern of torque and not by an elastic mechanism. Results showed that balance was achieved by the constant repetition of a neurally generated ballistic-like biphasic pattern of torque which can control both position and sway size. A decomposition technique revealed that there was a substantial contribution to changes in torque from intrinsic mechanical ankle stiffness; however, by itself this was insufficient to maintain balance or to control position. Minimisation of sway size was caused by improvement in the accuracy of the anticipatory torque impulses. We hypothesise that examination of centre of mass and centre of pressure data for quiet standing will duplicate these results. PMID:11986396

University of Florida Torsion Pendulum for Testing Key LISA Technology

NASA Astrophysics Data System (ADS)

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.

Evaluation of dynamic electromagnetic tracking deviation

NASA Astrophysics Data System (ADS)

Hummel, Johann; Figl, Michael; Bax, Michael; Shahidi, Ramin; Bergmann, Helmar; Birkfellner, Wolfgang

2009-02-01

Electromagnetic tracking systems (EMTS's) are widely used in clinical applications. Many reports have evaluated their static behavior and errors caused by metallic objects were examined. Although there exist some publications concerning the dynamic behavior of EMTS's the measurement protocols are either difficult to reproduce with respect of the movement path or only accomplished at high technical effort. Because dynamic behavior is of major interest with respect to clinical applications we established a simple but effective modal measurement easy to repeat at other laboratories. We built a simple pendulum where the sensor of our EMTS (Aurora, NDI, CA) could be mounted. The pendulum was mounted on a special bearing to guarantee that the pendulum path is planar. This assumption was tested before starting the measurements. All relevant parameters defining the pendulum motion such as rotation center and length are determined by static measurement at satisfactory accuracy. Then position and orientation data were gathered over a time period of 8 seconds and timestamps were recorded. Data analysis provided a positioning error and an overall error combining both position and orientation. All errors were calculated by means of the well know equations concerning pendulum movement. Additionally, latency - the elapsed time from input motion until the immediate consequences of that input are available - was calculated using well-known equations for mechanical pendulums for different velocities. We repeated the measurements with different metal objects (rods made of stainless steel type 303 and 416) between field generator and pendulum. We found a root mean square error (eRMS) of 1.02mm with respect to the distance of the sensor position to the fit plane (maximum error emax = 2.31mm, minimum error emin = -2.36mm). The eRMS for positional error amounted to 1.32mm while the overall error was 3.24 mm. The latency at a pendulum angle of 0° (vertical) was 7.8ms.

3-D simulation of hanging wall effect at dam site

NASA Astrophysics Data System (ADS)

Zhang, L.; Xu, Y.

2017-12-01

Hanging wall effect is one of the near fault effects. This paper focuses on the difference of the ground motions on the hanging wall side between the footwall side of the fault at dam site considering the key factors, such as actual topography, the rupture process. For this purpose, 3-D ground motions are numerically simulated by the spectrum element method (SEM), which takes into account the physical mechanism of generation and propagation of seismic waves. With the SEM model of 548 million DOFs, excitation and propagation of seismic waves are simulated to compare the difference between the ground motion on the hanging wall side and that on the footwall side. Take Dagangshan region located in China as an example, several seismogenic finite faults with different dip angle are simulated to investigate the hanging wall effect. Furthermore, by comparing the ground motions of the receiving points, the influence of several factors on hanging wall effect is investigated, such as the dip of the fault and the fault type (strike slip fault or dip-slip fault). The peak acceleration on the hanging wall side is obviously larger than those on the footwall side, which numerically evidences the hanging wall effect. Besides, the simulation shows that only when the dip is less than 70° does the hanging wall effect deserve attention.

Integrated Data Collection and Analysis Project: Friction Correlation Study

DTIC Science & Technology

2015-08-01

methods authorized in AOP-7 include Pendulum Friction, Rotary Friction, Sliding Friction (ABL), BAM Friction and Steel/Fiber Shoe Methods. The...sensitivity can be obtained by Pendulum Friction, Rotary Friction, Sliding Friction (such as the ABL), BAM Friction and Steel/Fiber Shoe Methods.3, 4 Within...Figure 4.16 A variable compressive force is applied downward through the wheel hydraulically (50-1995 psi). The 5 kg pendulum impacts (8 ft/sec is the

Quantum Simulation and Quantum Sensing with Ultracold Strontium

DTIC Science & Technology

2015-09-18

quantum Kapitza pendulum , a novel Floquet system which we are investigating using modulated optical lattices. We have proposed and are developing...another goal of our AFOSR YIP project. To this end, we have developed the first theoretical treatment of a lattice-based quantum Kapitza pendulum . We have...classical single-particle analogue of this phase occurs in a rigid pendulum with an oscillating support (known as a Kapitza pendu- lum [9]). To prepare for

Two-Pendulum Model of Propellant Slosh in Europa Clipper PMD Tank

NASA Technical Reports Server (NTRS)

Ng, Wanyi; Benson, David

2017-01-01

Model propellant slosh for Europa Clipper using two pendulums such that controls engineers can predict slosh behavior during the mission. Importance of predicting propellant slosh; (1) Sloshing changes CM (center of mass) of spacecraft and exerts forces and torques on spacecraft. (2) Avoid natural frequencies of structures. (3) Size ACS (Attitude Control Systems) thrusters to counteract forces and torques. Can model sloshing fluid as two pendulums with specific parameters (mass, length, damping),

Revolutionizing Space Propulsion Through the Characterization of Iodine as Fuel for Hall-Effect Thrusters

DTIC Science & Technology

2011-03-01

for controlled thruster operation at varying conditions. An inverted pendulum was used to take thrust measurements. Thrust to power ratio, anode...for comparison will include thrust, T. Thrust 21 can be measured by a sensitive inverted pendulum thrust stand. Specific impulse would be...to this pressure. III.4 Diagnostic Equipment The instrument used to take thrust measurements was the Busek T8 inverted pendulum thrust stand [13

An Empirical Model for Mine-Blast Loading

DTIC Science & Technology

2014-10-17

fledged experimental program. The numerical approach however suffers from several drawbacks in the mine blast simulations. First, it is a very...Suffield consisted in a pendulum type device to measure global impulse of buried mine [15]. One of the main purposes of the ONAGER pendulum was to study...TP-1 Terminal effects, KTA 1-34 report, 2004. [15] Bues, R., Hlady, S.L. and Bergeron, D.M., Pendulum Measurement of Land Mine Blast Output, Volume

Simple pendulum for blind students

NASA Astrophysics Data System (ADS)

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.

Precision Measurement of Distribution of Film Thickness on Pendulum for Experiment of G

NASA Astrophysics Data System (ADS)

Liu, Lin-Xia; Guan, Sheng-Guo; Liu, Qi; Zhang, Ya-Ting; Shao, Cheng-Gang; Luo, Jun

2009-09-01

Distribution of film thickness coated on the pendulum of measuring the Newton gravitational constant G is determined with a weighing method by means of a precision mass comparator. The experimental result shows that the gold film on the pendulum will contribute a correction of -24.3 ppm to our G measurement with an uncertainty of 4.3 ppm, which is significant for improving the G value with high precision.

Pendulum motions of extended lunar space elevator

NASA Astrophysics Data System (ADS)

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 motion of the lunar tether system was considered in [8]. The alternation of stable and unstable flat oscillations is well known in the problem of satellite oscillations in a circular orbit [9, 10].

Light rays and the tidal gravitational pendulum

NASA Astrophysics Data System (ADS)

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 congruence.

Two-Pendulum Model of Propellant Slosh in Europa Clipper PMD Tank

NASA Technical Reports Server (NTRS)

Ng, Wanyi; Benson, David

2017-01-01

The objective of this fluids analysis is to model propellant slosh for the Europa Clipper mission using a two-pendulum model, such that controls engineers can predict slosh behavior during the mission. Propellant slosh causes shifts in center of mass and exerts forces and torques on the spacecraft which, if not adequately controlled, can lead to mission failure. The two-pendulum model provides a computationally simple model that can be used to predict slosh for the Europa Clipper tank geometry. The Europa Clipper tank is cylindrical with a domed top and bottom and includes a propellant management device (PMD). Due to the lack of experimental data in low gravity environments, computational fluid dynamics (CFD) simulation results were used as 'real' slosh behavior for two propellants at three fill fractions. Key pendulum parameters were derived that allow the pendulum model's center of mass, forces, and moments to closely match the CFD data. The parameter trends were examined as a function of tank fill fraction and compared with solutions to analytic equations that describe the frequency of slosh in tanks with simple geometries. The trends were monotonic as expected, and parameters resembled analytical predictions; any differences could be explained by the specific differences in the geometry of the tank. This paper summarizes the new method developed at Goddard Space Flight Center (GSFC) for deriving pendulum parameters for two-pendulum equivalent sloshing models. It presents the results of this method and discusses the validity of the results. This analysis is at a completed stage and will be applied in the immediate future to the evolving tank geometry as Europa Clipper moves past its preliminary design review (PDR) phase.

Reachability and Real-Time Actuation Strategies for the Active SLIP Model

DTIC Science & Technology

2015-06-01

spring leg, the Spring Loaded Inverted Pendulum (SLIP) is a prevalent model for analyzing running and hopping. In this work we consider an actuated...forced symmetry of the stance phase for the Spring-Loaded Inverted Pendulum , In Proceedings of the 2012 IEEE International Conference on Robotics and...Networks. Automatica, 49(1):206-213, 2013 (v) G. Piovan and K. Byl. Enforced symmetry of the stance phase for the spring-loaded inverted pendulum . In

Lyapunov optimal feedback control of a nonlinear inverted pendulum

NASA Technical Reports Server (NTRS)

Grantham, W. J.; Anderson, M. J.

1989-01-01

Liapunov optimal feedback control is applied to a nonlinear inverted pendulum in which the control torque was constrained to be less than the nonlinear gravity torque in the model. This necessitates a control algorithm which 'rocks' the pendulum out of its potential wells, in order to stabilize it at a unique vertical position. Simulation results indicate that a preliminary Liapunov feedback controller can successfully overcome the nonlinearity and bring almost all trajectories to the target.

UT Austin Villa 2011: 3D Simulation Team Report

DTIC Science & Technology

2011-01-01

inverted pendulum model omnidirectional walk engine based on one that was originally designed for the real Nao robot [7]. The omnidirectional walk is...using a double linear inverted pendulum , where the center of mass is swinging over the stance foot. In addition, as in Graf et al.’s work [7], we use...between the inverted pendulums formed by the respective stance feet. Notation Description maxStep∗i Maximum step sizes allowed for x, y, and θ y

Reliability and validity of pendulum test measures of spasticity obtained with the Polhemus tracking system from patients with chronic stroke

PubMed Central

Bohannon, Richard W; Harrison, Steven; Kinsella-Shaw, Jeffrey

2009-01-01

Background Spasticity is a common impairment accompanying stroke. Spasticity of the quadriceps femoris muscle can be quantified using the pendulum test. The measurement properties of pendular kinematics captured using a magnetic tracking system has not been studied among patients who have experienced a stroke. Therefore, this study describes the test-retest reliability and known groups and convergent validity of the pendulum test measures obtained with the Polhemus tracking system. Methods Eight patients with chronic stroke underwent pendulum tests with their affected and unaffected lower limbs, with and without the addition of a 2.2 kg cuff weight at the ankle, using the Polhemus magnetic tracking system. Also measured bilaterally were knee resting angles, Ashworth scores (grades 0–4) of quadriceps femoris muscles, patellar tendon (knee jerk) reflexes (grades 0–4), and isometric knee extension force. Results Three measures obtained from pendular traces of the affected side were reliable (intraclass correlation coefficient ≥ .844). Known groups validity was confirmed by demonstration of a significant difference in the measurements between sides. Convergent validity was supported by correlations ≥ .57 between pendulum test measures and other measures reflective of spasticity. Conclusion Pendulum test measures obtained with the Polhemus tracking system from the affected side of patients with stroke have good test-retest reliability and both known groups and convergent validity. PMID:19642989

Comparison of two different methods of preoperative marking for toric intraocular lens implantation: bubble marker versus pendulum marker.

PubMed

Farooqui, Javed Hussain; Koul, Archana; Dutta, Ranjan; Shroff, Noshir Minoo

2016-01-01

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. 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. 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). Both preoperative marking techniques result in approximately 3 of alignment error. Both marking techniques are simple, predictable, reproducible and easy to perform.

Reliability and validity of pendulum test measures of spasticity obtained with the Polhemus tracking system from patients with chronic stroke.

PubMed

Bohannon, Richard W; Harrison, Steven; Kinsella-Shaw, Jeffrey

2009-07-30

Spasticity is a common impairment accompanying stroke. Spasticity of the quadriceps femoris muscle can be quantified using the pendulum test. The measurement properties of pendular kinematics captured using a magnetic tracking system has not been studied among patients who have experienced a stroke. Therefore, this study describes the test-retest reliability and known groups and convergent validity of the pendulum test measures obtained with the Polhemus tracking system. Eight patients with chronic stroke underwent pendulum tests with their affected and unaffected lower limbs, with and without the addition of a 2.2 kg cuff weight at the ankle, using the Polhemus magnetic tracking system. Also measured bilaterally were knee resting angles, Ashworth scores (grades 0-4) of quadriceps femoris muscles, patellar tendon (knee jerk) reflexes (grades 0-4), and isometric knee extension force. Three measures obtained from pendular traces of the affected side were reliable (intraclass correlation coefficient > or = .844). Known groups validity was confirmed by demonstration of a significant difference in the measurements between sides. Convergent validity was supported by correlations > or = .57 between pendulum test measures and other measures reflective of spasticity. Pendulum test measures obtained with the Polhemus tracking system from the affected side of patients with stroke have good test-retest reliability and both known groups and convergent validity.

A swing driven by liquid crystals

NASA Astrophysics Data System (ADS)

Cheng, Cheng

Angular momentum in liquid crystals exists as flow, director reorientation, etc. However, it is hard to observe and measure angular momentum in liquid crystals by a direct mechanical approach. Torsion pendulum is a general tool to measure angular momentum by torque balance. Our torsion pendulum can harvest the angular momentum in liquid crystals to make it observable. The oscillation of the pendulum keeps increasing by constructively adding a small angular momentum of liquid crystals each period at the resonant frequency of the pendulum. Its similar to a swing driven by a force at its resonant frequency. For the torsion pendulum, a cage made of two aluminum discs, in which a liquid crystal cell is placed, is suspended between two thin tungsten wires. A gold mirror, which is a part of the optical lever system, is attached on one tungsten wire. As first demonstration, we fabricate a circular hybrid liquid crystal cell, which can induce concentric backflows to generate angular momentum. The alignment on the planar substrate is concentric and tangential. Due to the coupling between director rotation and flow, the induced backflow goes around the cell when we add electrical pulses between top and bottom substrates. The oscillation is observed by a position sensitive detector and analyzed on the basis of Eriksen-Leslie theory. With vacuum condition and synchronous driving system, the oscillation signal is improved. We demonstrate that this torsion pendulum can sensitively detect the angular momentum in liquid crystals.

Hanging out with Which Friends? Friendship-Level Predictors of Unstructured and Unsupervised Socializing in Adolescence

ERIC Educational Resources Information Center

Siennick, Sonja E.; Osgood, D. Wayne

2012-01-01

Companions are central to explanations of the risky nature of unstructured and unsupervised socializing, yet we know little about whom adolescents are with when hanging out. We examine predictors of how often friendship dyads hang out via multilevel analyses of longitudinal friendship-level data on over 5,000 middle schoolers. Adolescents hang out…

A composite controller for trajectory tracking applied to the Furuta pendulum.

PubMed

Aguilar-Avelar, Carlos; Moreno-Valenzuela, Javier

2015-07-01

In this paper, a new composite scheme is proposed, where the total control action is composed of the sum of a feedback-linearization-based controller and an energy-based compensation. This new proposition is applied to the rotary inverted pendulum or Furuta pendulum. The Furuta pendulum is a well-known underactuated mechanical system with two degrees of freedom. The control objective in this case is the tracking of a desired periodic trajectory in the actuated joint, while the unactuated link is regulated at the upward position. The closed-loop system is analyzed showing uniformly ultimately boundedness of the error trajectories. The design procedure is shown in a constructive form, such that it may be applied to other underactuated mechanical systems, with the proper definitions of the output function and the energy function. Numerical simulations and real-time experiments show the practical viability of the controller. Finally, the proposed algorithm is compared with a tracking controller previously reported in the literature. The new algorithm shows better performance in both arm trajectory tracking and pendulum regulation. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Seismic cross-coupling noise in torsion pendulums

NASA Astrophysics Data System (ADS)

Shimoda, Tomofumi; Aritomi, Naoki; Shoda, Ayaka; Michimura, Yuta; Ando, Masaki

2018-05-01

Detection of low-frequency gravitational waves around 0.1 Hz is one of the important targets for future gravitational wave observation. One of the main sources of the expected signals is gravitational waves from binary intermediate-mass black hole coalescences which is proposed as one of the formation scenarios of supermassive black holes. By using a torsion pendulum, which can have a resonance frequency of a few millihertz, such signals can be measured on the ground since its rotational motion can act as a free mass down to 0.01 Hz. However, sensitivity of a realistic torsion pendulum will suffer from torsional displacement noise introduced from translational ground motion in the main frequency band of interest. Such noise is called seismic cross-coupling noise, and there has been little research on it. In this paper, systematic investigation is performed to identify routes of cross-coupling transfer for standard torsion pendulums. Based on the results, this paper also proposes reduction schemes of cross-coupling noise, and they were demonstrated experimentally in agreement with theory. This result establishes a basic way to reduce seismic noise in torsion pendulums for the most significant coupling routes.

Neural network-based motion control of an underactuated wheeled inverted pendulum model.

PubMed

Yang, Chenguang; Li, Zhijun; Cui, Rongxin; Xu, Bugong

2014-11-01

In this paper, automatic motion control is investigated for one of wheeled inverted pendulum (WIP) models, which have been widely applied for modeling of a large range of two wheeled modern vehicles. First, the underactuated WIP model is decomposed into a fully actuated second order subsystem Σa consisting of planar movement of vehicle forward and yaw angular motions, and a nonactuated first order subsystem Σb of pendulum motion. Due to the unknown dynamics of subsystem Σa and the universal approximation ability of neural network (NN), an adaptive NN scheme has been employed for motion control of subsystem Σa . The model reference approach has been used whereas the reference model is optimized by the finite time linear quadratic regulation technique. The pendulum motion in the passive subsystem Σb is indirectly controlled using the dynamic coupling with planar forward motion of subsystem Σa , such that satisfactory tracking of a set pendulum tilt angle can be guaranteed. Rigours theoretic analysis has been established, and simulation studies have been performed to demonstrate the developed method.

Attitude Stability of a Spacecraft with Slosh Mass Subject to Parametric Excitation

NASA Astrophysics Data System (ADS)

Kang, Ja-Young

2003-09-01

The attitude motion of a spin-stabilized, upper-stage spacecraft is investigated based on a two-body model, consisting of a symmetric body, representing the spacecraft, and a spherical pendulum, representing the liquid slag pool entrapped in the aft section of the rocket motor. Exact time-varying nonlinear equations are derived and used to eliminate the drawbacks of conventional linear models. To study the stability of the spacecraft's attitude motion, both the spacecraft and pendulum are assumed to be in states of steady spin about the symmetry axis of the spacecraft and the coupled time-varying nonlinear equation of the pendulum is simplified. A quasi-stationary solution to that equation and approximate resonance conditions are determined in terms of the system parameters. The analysis shows that the pendulum is subject to a combination of parametric and external-type excitation by the main body and that energy from the excited pendulum is fed into the main body to develop the coning instability. In this paper, numerical examples are presented to explain the mechanism of the coning angle growth and how angular momenta and disturbance moments are generated.

Piaget and the Pendulum

NASA Astrophysics Data System (ADS)

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.

Ratchet baryogenesis and an analogy with the forced pendulum

NASA Astrophysics Data System (ADS)

Bamba, Kazuharu; Barrie, Neil D.; Sugamoto, Akio; Takeuchi, Tatsu; Yamashita, Kimiko

2018-06-01

A new scenario of baryogenesis via the ratchet mechanism is proposed based on an analogy with the forced pendulum. The oscillation of the inflaton field during the reheating epoch after inflation plays the role of the driving force, while the phase 𝜃 of a scalar baryon field (a complex scalar field with baryon number) plays the role of the angle of the pendulum. When the inflaton is coupled to the scalar baryon, the behavior of the phase 𝜃 can be analogous to that of the angle of the forced pendulum. If the oscillation of the driving force is adjusted to the pendulum’s motion, a directed rotation of the pendulum is obtained with a nonvanishing value of 𝜃˙, which models successful baryogenesis since 𝜃˙ is proportional to the baryon number density. Similar ratchet models which lead to directed motion have been used in the study of molecular motors in biology. There, the driving force is supplied by chemical reactions, while in our scenario this role is played by the inflaton during the reheating epoch.

Suicidal Decapitation by Hanging-A Population-based Study.

PubMed

Byard, Roger W; Gilbert, John D

2018-05-01

A prospective study was undertaken at Forensic Science SA over a 15-year period from July 2002 to June 2017 for all cases of adult (>18 years) suicidal hangings with decapitation. A total of 1446 cases of suicidal hangings were identified from a general population of approximately 1.5 million (1206 males-age range 18-97 years, average 42.6; and 240 females-age range 18-96 years, average 40.1). Only three cases of decapitation were found, all from long-drop hangings; these consisted of three males (ages 32-55 years; average 45 years). Spinal transections had occurred between the first and second, second and third, and third and fourth cervical vertebrae, respectively. In this study, the number of suicidal hangings with decapitation represented only 0.2% of the total number of hangings. These events are therefore extremely rare, most likely due to most suicidal hangings occurring from relatively low levels in a domestic environment. © 2017 American Academy of Forensic Sciences.

Hands Tied with Bag Full of Books in Suicidal Hanging.

PubMed

Sikary, Asit Kumar; Behera, Chittaranjan; Murty, Om Prakash; Rautji, Ravi

2016-01-01

Hanging deaths associated with binding of limbs, masking of a face, and gagging are always suspicious. In suicidal hanging, the victim uses these added techniques to prevent him from backing out of his decision and to ensure death. However, binding of limbs and adding extra weight to the suspension in hanging are not reported. Herein, we report a case where the victim tied a bag containing books weighing 7 kg (15.4 lbs) to both his hands during hanging. The forensic specialist must be aware of the unusual presentation of suicidal hanging which may suggest foul play. The manner of death must be established after detailed analysis of circumstantial evidence, information obtained from the witnesses, complete autopsy, and toxicological examination. © 2015 American Academy of Forensic Sciences.

The sympathy of two pendulum clocks: beyond Huygens' observations.

PubMed

Peña Ramirez, Jonatan; Olvera, Luis Alberto; Nijmeijer, Henk; Alvarez, Joaquin

2016-03-29

This paper introduces a modern version of the classical Huygens' experiment on synchronization of pendulum clocks. The version presented here consists of two monumental pendulum clocks--ad hoc designed and fabricated--which are coupled through a wooden structure. It is demonstrated that the coupled clocks exhibit 'sympathetic' motion, i.e. the pendula of the clocks oscillate in consonance and in the same direction. Interestingly, when the clocks are synchronized, the common oscillation frequency decreases, i.e. the clocks become slow and inaccurate. In order to rigorously explain these findings, a mathematical model for the coupled clocks is obtained by using well-established physical and mechanical laws and likewise, a theoretical analysis is conducted. Ultimately, the sympathy of two monumental pendulum clocks, interacting via a flexible coupling structure, is experimentally, numerically, and analytically demonstrated.

Parametric pendulum based wave energy converter

NASA Astrophysics Data System (ADS)

Yurchenko, Daniil; Alevras, Panagiotis

2018-01-01

The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

Earthquake Facts

MedlinePlus

... recordings of large earthquakes, scientists built large spring-pendulum seismometers in an attempt to record the long- ... are moving away from one another. The first “pendulum seismoscope” to measure the shaking of the ground ...

Stability of controlled inverted pendulum under permanent horizontal perturbations of the supporting point

NASA Astrophysics Data System (ADS)

Aleksandrov, V. V.; Reyes-Romero, M.; Sidorenko, G. Yu.; Temoltzi-Auila, R.

2010-04-01

We consider the problem of choosing a test perturbation of a movable foundation of a single-link inverted pendulum so as to test a vestibular prosthesis prototype located at the top of this pendulum in an extreme situation. The obtained results permit concluding that the information transmitted from otolithic organs of the human vestibular system to muscles of the locomotor apparatus is very important and improves the quality of stabilization of the human vertical posture preventing the possible fall.

11. BUILDING NO. 620B. INTERIOR VIEW LOOKING NORTH, SHOWING PENDULUM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. BUILDING NO. 620-B. INTERIOR VIEW LOOKING NORTH, SHOWING PENDULUM AND FRAME IN FOREGROUND, SHIELD FOR OPERATORS IN BACKGROUND. FRICTION TEST IS OBSERVED FROM BEHIND BLAST SHIELD BY A SERIES OF MIRRORS. ANVIL IN CENTER OF PENDULUM FRAME HOLDS EXPLOSIVE WHOSE SENSITIVITY TO FRICTION IS TO BE TESTED. PANS ON EITHER SIDE CATCH ANY UNBURNT EXPLOSIVE SLUNG FROM ANVIL DURING TEST TO PREVENT EXPLOSIVE HAZARD. - Picatinny Arsenal, 600 Area, Test Areas District, State Route 15 near I-80, Dover, Morris County, NJ

Dynamic Accuracy of Inertial Magnetic Sensor Modules

DTIC Science & Technology

2016-12-01

and the cost of the YEI 3-space data-logging sensor was justified. C. PREVIOUS WORK In [7], Jeremy Cookson built a low-cost pendulum with an optical...encoder to test the dynamic accuracy of MARG sensor modules. The pendulum was designed in order to execute dynamic, repeatable tests in a single...3DM-GX1 and 3DM-GX3-25 sensors. In [8], Leslie Landry developed similar repeatable tests and utilized the pendulum to test the dynamic accuracy of

Advancements of In-Flight Mass Moment of Inertia and Structural Deflection Algorithms for Satellite Attitude Simulators

DTIC Science & Technology

2015-03-26

pendulum [15] to estimate the MOI. The benefit to this methodology is that instead of a direct comparison to Euler’s equations when using an on-board ACS...the equations of motion of pendulum motion are evaluated to estimate the resistance to angular acceleration. Instead of attempting to compare noisy...sensor data instantaneously when using on-board ACS data, the pendulum oscillation frequency is estimated, which can be globally smoothed for highly

Integrated Reconfigurable Intelligent Systems (IRIS) for Complex Naval Systems

DTIC Science & Technology

2011-02-23

INTRODUCTION 35 2.2 GENERAL MODEL SETUP 36 2.2.1 Co-Simulation Principles 36 2.2.2 Double pendulum : a simple example 38 2.2.3 Description of numerical... pendulum sample problem 45 2.3 DISCUSSION OF APPROACH WITH RESPECT TO PROPOSED SUBTASKS 49 2.4 RESULTS DISCUSSION AND FUTURE WORK 49 TASK 3...Kim and Praehofer 2000]. 2.2.2 Double pendulum : a simple example In order to be able to evaluate co-simulation principles, specifically an

Measuring g Using a Magnetic Pendulum and Telephone Pickup

NASA Astrophysics Data System (ADS)

Sinacore, J.; Takai, H.

2010-10-01

The simple pendulum has long been used to measure g, the acceleration due to gravity, with a precision of a few percent. Achieving agreement with the accepted value of less than 1% is feasible in the high school laboratory, though it requires some care. The precision of the measurement is bound by how accurately the period and the pendulum length are determined. To improve on the period measurement, we have developed a simple and inexpensive method using a magnet and telephone pickup.2

Evaluation of Vitality in the Experimental Hanging Model of Rats by Using Immunohistochemical IL-1β Antibody Staining.

PubMed

Balandiz, Hüseyin; Pehlivan, Sultan; Çiçek, Ali Fuat; Tuğcu, Harun

2015-12-01

Hanging is the most common suicide method in the world, and the discrimination of antemortem-postmortem hanging must be done at autopsy. The aim of this experimental study was to examine the immunohistochemical expression of IL-1β antibody at the hanging mark skin samples of rats to discriminate antemortem and postmortem hangings. A total of 20 Wistar albino rats were used for this study. The groups were as follows: A-1, antemortem control group; A-2, antemortem second-hour hanging mark skin samples; A-3, antemortem 24th-hour hanging mark skin samples; A-4, antemortem 72nd-hour hanging mark skin samples; B-1, postmortem control group; and B-2, postmortem second-hour hanging mark skin samples. Interleukin-1β immunostaining was performed to all tissue samples. For epidermal cells, group A-1 samples did not show IL-1β immunostaining, group A-2 samples were severely immunostained, and groups A-3 and A-4 samples' staining were slightly decreased. There was no IL-1β antibody staining in groups B-1 and B-2 samples. For adnexal cells, groups A-1 and B-1 samples did not show IL-1β immunostaining, staining of group A-2 samples was mild to severe, and groups A-3 and A-4 samples' staining were slightly decreased. Half of the group B-2 samples did not show IL-1β immunostaining. For subepidermal cells, most of the samples of groups A-1 and B-1 showed slight immunostaining, groups A-2 and B-2 samples' staining were mild to severe, and there were slight immunostaining in groups A-3 and A-4 samples. The majority of vascular structure cells did not show IL-1β immunostaining. Interleukin-1β immunostaining of epidermal cells can discriminate antemortem-postmortem hangings, but vascular structure cells and subepidermal cells cannot discriminate vital hangings.

State Estimation for Humanoid Robots

DTIC Science & Technology

2015-07-01

21 2.2.1 Linear Inverted Pendulum Model . . . . . . . . . . . . . . . . . . . 21 2.2.2 Planar Five-link Model...Linear Inverted Pendulum Model. LVDT Linear Variable Differential Transformers. MEMS Microelectromechanical Systems. MHE Moving Horizon Estimator. QP...

Changes in stature following plyometric drop-jump and pendulum exercises.

PubMed

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 < 0.05) change in stature (-2.71 +/- 0.8 mm), compared to pendulum exercises (-1.77 +/- 0.7 mm) and standing (-0.39 +/- 0.2 mm). Both exercise regimens resulted in a significant (p < 0.01) decrease in stature when compared to the standing condition. Drop-jumps resulted in significantly greater peak impact forces (p < 0.05) than pendulum exercises (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.

49 CFR 572.127 - Test conditions and instrumentation.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Forces—Class 1000; (ii) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation—Class 60 (if used). (3) Thorax: (i) Rib acceleration—Class 1000; (ii) Spine and pendulum accelerations—Class...

49 CFR 572.127 - Test conditions and instrumentation.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Forces—Class 1000; (ii) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation—Class 60 (if used). (3) Thorax: (i) Rib acceleration—Class 1000; (ii) Spine and pendulum accelerations—Class...

49 CFR 572.127 - Test conditions and instrumentation.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Forces—Class 1000; (ii) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation—Class 60 (if used). (3) Thorax: (i) Rib acceleration—Class 1000; (ii) Spine and pendulum accelerations—Class...

49 CFR 572.127 - Test conditions and instrumentation.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Forces—Class 1000; (ii) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation—Class 60 (if used). (3) Thorax: (i) Rib acceleration—Class 1000; (ii) Spine and pendulum accelerations—Class...

49 CFR 572.127 - Test conditions and instrumentation.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Forces—Class 1000; (ii) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation—Class 60 (if used). (3) Thorax: (i) Rib acceleration—Class 1000; (ii) Spine and pendulum accelerations—Class...

Suicidal hanging within an automobile.

PubMed

Blanco Pampin, J M; López-Abajo Rodriguez, B A

2001-12-01

Accidental asphyxia related to cars has been described in different reports, but suicidal hanging in an automobile is very unusual. Two cases of suicidal hanging inside an automobile are described, illustrating an unusual form of hanging. In one case, the deceased used his belt as a ligature, and the point of attachment was the window of the car. The second victim used the safety belt of the passenger seat. In both cases, the automobile engine was turned off, all the windows were closed, and the door locks were blocked. The medicolegal cause of hanging was based on the scene of the investigation, police and witness reports, social history, autopsy findings, and toxicologic examinations.

49 CFR 572.146 - Test conditions and instrumentation.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Head acceleration—Class 1000 (2) Neck (i) Force—Class 1000 (ii) Moments—Class 600 (iii) Pendulum... acceleration—Class 1000 (ii) Spine and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv...

49 CFR 572.155 - Test conditions and instrumentation.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation potentiometer response (if used)—CFC 60. (3) Thorax: (i) Spine and pendulum accelerations—Class 180; (ii) Shoulder forces—Class 600; (4...

49 CFR 572.155 - Test conditions and instrumentation.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation potentiometer response (if used)—CFC 60. (3) Thorax: (i) Spine and pendulum accelerations—Class 180; (ii) Shoulder forces—Class 600; (4...

49 CFR 572.177 - Test conditions and instrumentation.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) except as noted, with channel frequency classes as follows: (1) Pendulum acceleration, CFC 180, (2) Pendulum D-plane rotation (if transducer is used), CFC 60, (3) Torso flexion pulling force (if transducer...

49 CFR 572.177 - Test conditions and instrumentation.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) except as noted, with channel frequency classes as follows: (1) Pendulum acceleration, CFC 180, (2) Pendulum D-plane rotation (if transducer is used), CFC 60, (3) Torso flexion pulling force (if transducer...

49 CFR 572.155 - Test conditions and instrumentation.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation potentiometer response (if used)—CFC 60. (3) Thorax: (i) Spine and pendulum accelerations—Class 180; (ii) Shoulder forces—Class 600; (4...

49 CFR 572.146 - Test conditions and instrumentation.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Head acceleration—Class 1000 (2) Neck (i) Force—Class 1000 (ii) Moments—Class 600 (iii) Pendulum... acceleration—Class 1000 (ii) Spine and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv...

49 CFR 572.146 - Test conditions and instrumentation.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Head acceleration—Class 1000 (2) Neck (i) Force—Class 1000 (ii) Moments—Class 600 (iii) Pendulum... acceleration—Class 1000 (ii) Spine and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv...

49 CFR 572.155 - Test conditions and instrumentation.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation potentiometer response (if used)—CFC 60. (3) Thorax: (i) Spine and pendulum accelerations—Class 180; (ii) Shoulder forces—Class 600; (4...

49 CFR 572.146 - Test conditions and instrumentation.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Head acceleration—Class 1000 (2) Neck (i) Force—Class 1000 (ii) Moments—Class 600 (iii) Pendulum... acceleration—Class 1000 (ii) Spine and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv...

49 CFR 572.146 - Test conditions and instrumentation.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Head acceleration—Class 1000 (2) Neck (i) Force—Class 1000 (ii) Moments—Class 600 (iii) Pendulum... acceleration—Class 1000 (ii) Spine and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv...

49 CFR 572.155 - Test conditions and instrumentation.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Moments—Class 600; (iii) Pendulum acceleration—Class 180; (iv) Rotation potentiometer response (if used)—CFC 60. (3) Thorax: (i) Spine and pendulum accelerations—Class 180; (ii) Shoulder forces—Class 600; (4...

Health Information in Somali (Af-Soomaali )

MedlinePlus

... Af-Soomaali (Somali) Bilingual PDF Health Information Translations Pendulum Exercises for Shoulder - Af-Soomaali (Somali) Bilingual PDF ... Af-Soomaali (Somali) Bilingual PDF Health Information Translations Pendulum Exercises for Shoulder - Af-Soomaali (Somali) Bilingual PDF ...

49 CFR 572.177 - Test conditions and instrumentation.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) except as noted, with channel frequency classes as follows: (1) Pendulum acceleration, CFC 180, (2) Pendulum D-plane rotation (if transducer is used), CFC 60, (3) Torso flexion pulling force (if transducer...

Finite element analysis of unnotched charpy impact tests

DOT National Transportation Integrated Search

2008-10-01

This paper describes nonlinear finite element analysis (FEA) to examine the energy to : fracture unnotched Charpy specimens under pendulum impact loading. An oversized, : nonstandard pendulum impactor, called the Bulk Fracture Charpy Machine (BFCM), ...

Pendulum Therapy of Molar Distalization in Mixed Dentition.

PubMed

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.

Pendulum Therapy of Molar Distalization in Mixed Dentition

PubMed Central

Prakash, Amit; Agarwal, Anshu

2016-01-01

ABSTRACT 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. PMID:27274159

The sympathy of two pendulum clocks: beyond Huygens’ observations

PubMed Central

Peña Ramirez, Jonatan; Olvera, Luis Alberto; Nijmeijer, Henk; Alvarez, Joaquin

2016-01-01

This paper introduces a modern version of the classical Huygens’ experiment on synchronization of pendulum clocks. The version presented here consists of two monumental pendulum clocks—ad hoc designed and fabricated—which are coupled through a wooden structure. It is demonstrated that the coupled clocks exhibit ‘sympathetic’ motion, i.e. the pendula of the clocks oscillate in consonance and in the same direction. Interestingly, when the clocks are synchronized, the common oscillation frequency decreases, i.e. the clocks become slow and inaccurate. In order to rigorously explain these findings, a mathematical model for the coupled clocks is obtained by using well-established physical and mechanical laws and likewise, a theoretical analysis is conducted. Ultimately, the sympathy of two monumental pendulum clocks, interacting via a flexible coupling structure, is experimentally, numerically, and analytically demonstrated. PMID:27020903

Segmented Hoop as a Physical Pendulum

NASA Astrophysics Data System (ADS)

Layton, William; Rodriguez, Nuria

2013-10-01

An interesting demonstration with a surprising result is to suspend a hoop from a point near its edge and set it swinging in a vertical plane as a pendulum. If a simple pendulum of length equal to the diameter of the hoop is set oscillating at the same time, the two will have nearly the same period. However, the real surprise is if the pendulum is segmented horizontally (as illustrated in Fig. 1) into smaller pieces that are symmetrical about the point of suspension, each smaller segment will also have the same period. Constructing such a demonstration can be difficult, but thanks to a suggestion from a fellow physics teacher a dissectible hula hoop can be purchased that serves well in this demonstration.2 A setup that has been repeated many times at various physics teacher meetings in Southern California is illustrated below.

[Isolation and preparation of an imidazole alkaloid from radix radix of Aconitum pendulum Busch by semi-preparative high-speed counter-current chromatography].

PubMed

Liu, Yongling; Chen, Tao; Chen, Chen; Zou, Denglang; Li, Yulin

2014-05-01

Aconitum pendulum Busch is rich C19 diterpenoid alkaloids, but there is no report of imidazole alkaloid in Aconitum pendulum Busch. In this study, an imidazole alkaloid named 1H-imidazole-2-carboxylic acid, butyl ester (ICABE) was successfully separated from Aconitum pendulum Busch with semi-preparative high-speed counter-current chromatography (HSCCC). The partition coefficient was measured by HPLC to select the solvent systems for ICABE separation by HSCCC. The separation was performed with a two-phase solvent system composed of n-hexane-chloroform-ethanol-water (10:1 : 13:2, v/v/v/v). The upper phase was used as the stationary phase and the lower phase as the mobile phase. It was operated at a flow rate of 1.8 mL/min. The apparatus was rotated at 850 r/min, and the detection wavelength was set at 230 nm. Under the selected conditions, a high efficiency separation of HSCCC was achieved, and 7.5 mg of ICABE was obtained from 100 mg of the crude sample of Aconitum pendulum in one-step separation within 350 min. The HPLC analysis showed that the purity of the compound was over 98%. The chemical structure was confirmed by UV, 1H-NMR and 13C-NMR. The established method is simple, highly efficient and suitable for large scale separation of ICABE from radix of Aconitum pendulum Busch.

Comparison of two different methods of preoperative marking for toric intraocular lens implantation: bubble marker versus pendulum marker

PubMed Central

Farooqui, Javed Hussain; Koul, Archana; Dutta, Ranjan; Shroff, Noshir Minoo

2016-01-01

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. PMID:27275425

Modified Liver Hanging Maneuver for En-bloc Right-sided Hepatectomy Combined with Total Caudate Lobectomy for Colon-Cancer Liver Metastasis and Hepatocellular Carcinoma.

PubMed

Hiroshima, Yukihiko; Matsuo, Kenichi; Kawaguchi, Daisuke; Kikuchi, Yutaro; Endo, Itaru; Koda, Keiji; Togo, Shinji; Hoffman, Robert M; Tanaka, Kuniya

2016-04-01

A right-sided hepatectomy with total caudate lobectomy is indicated for colorectal-cancer liver metastases (CLM) and hepatocellular carcinomas (HCC) located in the caudate lobe with extension to the right lobe of the liver. Caudate-lobe resection (i.e. segmentectomy 1 according to the Brisbane terminology) is one of the most difficult types of hepatectomy to carry out radically and safely. The deep portion of hepatic transection around the caudate lobe, hepatic veins and inferior vena cava is a critical source of massive bleeding. Prolonged transection can increase blood loss. We analyzed the outcome of 10 patients who underwent right-sided hepatectomy with caudate lobectomy using a modified liver hanging maneuver (mLHM) in comparison with 16 patients who underwent the operation without mLHM. Blood loss during liver transection and blood loss per unit area of cut surface were significantly less in the mLHM group (p=0.014 and 0.015, respectively). In patients diagnosed pathologically with liver impairment, transection time was significantly shorter in the mLHM group (p=0.038), as were red blood cell transfusion volume (p=0.042) and blood loss (p=0.049) during transection. Use of mLHM can potentially improve surgical outcomes by reducing blood loss and transection time, which are especially important for patients with liver impairment. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Acute pulmonary emphysema in death by hanging: a morphometric digital study.

PubMed

Castiglioni, Claudia; Baumann, Pia; Fracasso, Tony

2016-09-01

Acute pulmonary emphysema (APE) has been described in cases of mechanical asphyxia such as ligature or manual strangulation but not in cases of hanging. In this study, we wanted to verify by morphometric digital analysis of lung tissue whether APE occurs in death by hanging.We investigated 16 cases of hanging (eight complete, eight incomplete), 10 cases of freshwater drowning (positive control group), and 10 cases of acute external bleeding (negative control group). Tissue sections were obtained from each pulmonary lobe. For each slide, five fields were randomly selected. The area of every alveolar space was measured by image analysis software. The mean alveolar area (MAA) was calculated for each group.In incomplete hanging, MAA was significantly higher than that observed in complete hanging and similar to the one observed in freshwater drowning.APE in cases of incomplete hanging can be considered as a sign of vitality. The high number of conditions that can cause alveolar distension (that were excluded in this study) limits the applicability of this vital sign in the routine forensic practice.

Agonal sequences in four filmed hangings: analysis of respiratory and movement responses to asphyxia by hanging.

PubMed

Sauvageau, Anny

2009-01-01

The human pathophysiology of asphyxia by hanging is still poorly understood, despite great advances in forensic science. In that context, filmed hangings may hold the key to answer questions regarding the sequence of events leading to death in human asphyxia. Four filmed hangings were analyzed. Rapid loss of consciousness was observed between 13 sec and 18 sec after onset of hanging, closely followed by convulsions (at 14-19 sec). A complex pattern of decerebration rigidity (19-21 sec in most cases), followed by a quick phase of decortication rigidity (1 min 00 sec-1 min 08 sec in most cases), an extended phase of decortication rigidity (1 min 04 sec-1 min 32 sec) and loss of muscle tone (1 min 38 sec-2 min 47 sec) was revealed. Very deep respiratory attempts started between 20 and 22 sec, the last respiratory attempt being detected between 2 min 00 sec and 2 min 04 sec. Despite differences in the types of hanging, this unique study reveals similarities that are further discussed.

Retrospective Analysis of Hanging Deaths in Ontario.

PubMed

Tugaleva, Elena; Gorassini, Donald R; Shkrum, Michael J

2016-11-01

Hanging deaths from investigation standpoint are rarely problematic. Unusual circumstances can on occasion raise suspicion of foul play. Associated neck injuries are reported in the literature with variable frequency (from 0% to 76.8%). This study retrospectively analyzed 755 hanging deaths in Ontario (Canada) to evaluate the demographic features and circumstances of hanging fatalities, and the frequency of hanging-related neck injuries. A number of cases showed unusual/special circumstances (e.g., complex, double suicides, restraints). Among 632 cases with complete autopsies, hyoid and larynx fractures were present in 46 cases (7.3%) with the most common being isolated hyoid fractures. The incidence of cricoid fractures was 0.5% and cervical spine injuries, 1.1%. A higher incidence of neck injuries occurred among males, long drop hangings, and in cases with complete suspension. There was a tendency for the number of fractures to increase with increasing age and weight of the deceased. © 2016 American Academy of Forensic Sciences.

Agonal sequences in a filmed suicidal hanging: analysis of respiratory and movement responses to asphyxia by hanging.

PubMed

Sauvageau, Anny; Racette, Stéphanie

2007-07-01

The forensic literature on the pathophysiology of human hanging is still limited. Therefore, forensic pathologists often feel uncomfortable when confronted with related questions. Here presented is the filmed suicidal hanging of a 37-year-old man. This recording allows a unique analysis of agonal movement sequences: loss of consciousness (13 sec), convulsions (15 sec), decortication rigidity (21 sec), decerebration rigidity (46 sec), second decortication rigidity (1 min 11 sec), loss of muscle tone, (1 min 38 sec) and last isolated muscle movement (4 min 10 sec). As for respiratory responses, very deep respiratory attempts started at 20 sec. Respiratory movements progressively decreased and completely stopped at 2 min. Despite the fact that extending the presented data on all cases of hanging asphyxia would be a mistake, this case gives a very interesting insight into movement and respiratory response to asphyxia by hanging.

Pendulum migration and healthcare in border área.

PubMed

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.

On periodic solutions of an Atwood's pendulum

NASA Astrophysics Data System (ADS)

Mittleman, Donald

1987-05-01

An Atwood's pendulum is defined as an Atwood's machine in which one of two masses is allowed to swing as a pendulum while the other remains constrained to move only in the vertical direction. The pendulum motion of the one mass induces a varying tension in the connecting wire; this, in turn, produces motion in the second mass. It is shown that this motion can be made periodic if the ratio of the two masses and the dependency of this ratio on the initial conditions are chosen as prescribed in this report. If this condition is not met, the motion consists of the superposition of two motions. The first is motion in a constant gravitational field where the effective gravity is kg; the factor k is determined explicitly. The second is the periodic motion that is the central theme of this report. During the course of the analysis, the fundamental frequency of the periodic motion is determined. It is shown to be slightly higher than the frequency of a pendulum of comparable length swinging in the Earth's gravitational field; the factor is given explicitly. This work is restricted to the extent that small approximations are introduced initially for trigonometric functions.

30 CFR 15.20 - Technical requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... temperature is between 68 and 86 °F. (f) Pendulum-friction test. The explosive shall show no perceptible reaction in the pendulum-friction test with the hard fiber-faced shoe. Ten trials of the test are conducted...

30 CFR 15.20 - Technical requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... temperature is between 68 and 86 °F. (f) Pendulum-friction test. The explosive shall show no perceptible reaction in the pendulum-friction test with the hard fiber-faced shoe. Ten trials of the test are conducted...

30 CFR 15.20 - Technical requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... temperature is between 68 and 86 °F. (f) Pendulum-friction test. The explosive shall show no perceptible reaction in the pendulum-friction test with the hard fiber-faced shoe. Ten trials of the test are conducted...

30 CFR 15.20 - Technical requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... temperature is between 68 and 86 °F. (f) Pendulum-friction test. The explosive shall show no perceptible reaction in the pendulum-friction test with the hard fiber-faced shoe. Ten trials of the test are conducted...

30 CFR 15.20 - Technical requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... temperature is between 68 and 86 °F. (f) Pendulum-friction test. The explosive shall show no perceptible reaction in the pendulum-friction test with the hard fiber-faced shoe. Ten trials of the test are conducted...

Demonstrating the Principle of an rf Paul Ion Trap

NASA Astrophysics Data System (ADS)

Johnson, Andrew; Rabchuk, James

2008-03-01

An rf ion trap uses a time-varying electric field to trap charged ions. This is useful in applications related to quantum computing and mass spectroscopy. There are several mechanical devices described in the literature which have attempted to provide illustrative demonstrations of the principle of rf ion traps, including a mechanically-rotating ``saddle trap'' and the vertically-driven, inverted pendulum^1,2. Neither demonstration, however, successfully demonstrates BOTH the sinusoidal variation in the electric potential of the rf trap AND the parametric stability of the ions in the trap described by Mathieu's equation. We have modified a design of a one-dimensional ponderomotive trap^3 so that it satisfies both criteria for demonstrating the principle of an rf Paul trap. Our studies indicate that trapping stability is highly sensitive to fluxuations in the driving frequency. Results from the demonstration apparatus constructed by the authors will be presented. ^1 Rueckner, W., et al., ``Rotating saddle Paul trap,'' Am. J. Phys., 63 (2), February 1995. ^2 Friedman, M.H., et al., ``The inverted pendulum: A mechanical analogue of a quadrupole mass filter,'' Am. J. Phys., 50 (10), October 1982. ^3 Johnson, A.K. and Rabchuk, J.A., ``A One-Dimensional Ponderomotive Trap,'' ISAAPT 2007 spring meeting, WIU, March 30, 2007.

Autonomous navigation system. [gyroscopic pendulum for air navigation

NASA Technical Reports Server (NTRS)

Merhav, S. J. (Inventor)

1981-01-01

An inertial navigation system utilizing a servo-controlled two degree of freedom pendulum to obtain specific force components in the locally level coordinate system is described. The pendulum includes a leveling gyroscope and an azimuth gyroscope supported on a two gimbal system. The specific force components in the locally level coordinate system are converted to components in the geographical coordinate system by means of a single Euler transformation. The standard navigation equations are solved to determine longitudinal and lateral velocities. Finally, vehicle position is determined by a further integration.

Self-excited electrostatic pendulum showing electrohydrodynamic-force-induced oscillation

NASA Astrophysics Data System (ADS)

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.

Analysis of pendulum period with an iPod touch/iPhone

NASA Astrophysics Data System (ADS)

Briggle, Justin

2013-05-01

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. Moreover, the principles described may be carried out with any number of smartphone devices containing an integrated accelerometer and paired with an appropriate application for collecting and sending accelerometer data as a comma-separated value file.

Bound Motion of Bodies and Paticles in the Rotating Systems

NASA Astrophysics Data System (ADS)

Pardy, Miroslav

2007-04-01

The Lagrange theory of particle motion in the noninertial systems is applied to the Foucault pendulum, isosceles triangle pendulum and the general triangle pendulum swinging on the rotating Earth. As an analogue, planet orbiting in the rotating galaxy is considered as the giant galactic gyroscope. The Lorentz equation and the Bargmann-Michel-Telegdi equations are generalized for the rotation system. The knowledge of these equations is inevitable for the construction of LHC where each orbital proton “feels” the Coriolis force caused by the rotation of the Earth.

White River National Forest Hanging Lake Capacity Study

DOT National Transportation Integrated Search

2016-05-01

Due to overcrowding at Hanging Lake, the Volpe Center performed a capacity study for the White River National Forest. This capacity study examines the visitation and environmental constraints of Hanging Lake parking lot, trail, and site to develop th...

Craniocervical injuries in judicial hangings: an anthropologic analysis of six cases.

PubMed

Spence, M W; Shkrum, M J; Ariss, A; Regan, J

1999-12-01

Restoration projects and archaeologic excavations in two Canadian prisons resulted in the recovery of the skeletons of six felons executed by judicial hanging. Damage inflicted by hanging on various skeletal elements was observed. Among the injuries seen were fractures of the hyoid cornua, styloid processes, occipital bones, and cervical vertebral bodies (C2) and transverse processes (C1, C2, C3, and C5). Despite the general uniformity of the hanging technique, which involved a subaural knot, the trauma to the skeletal elements and the cause of death varied among individuals. Although some of this variation was probably due to minor differences in hanging practices, individual anatomic peculiarities of the victims likely also contributed.

Misura di g con pendolo non in regime caotico

NASA Astrophysics Data System (ADS)

Sigismondi, Costantino

2017-02-01

The measurement of the gravity acceleration with pendulum is a basic experiment in Newtonian physics, but the correct choice of wire and weight to suspend can avoid to have a cahotic instead of simple pendulum.

Deck the Halls. Animated Displays: Coupled Mechanical Oscillators.

ERIC Educational Resources Information Center

Pizzo, Joe, Ed.

1992-01-01

Describes a set of displays on the theme of coupled mechanical oscillators. Displays encompass three common demonstrations: (1) a coupled pair of identical pendulums; (2) a multiple-pendulum resonance demonstration; and (3) a Wilberforce coupled oscillator. (MDH)

Tidal evolution of the Galilean satellites - A linearized theory

NASA Technical Reports Server (NTRS)

Greenberg, R.

1981-01-01

The Laplace resonance among the Galilean satellites Io, Europa, and Ganymede is traditionally reduced to a pendulum-like dynamical problem by neglecting short-period variations of several orbital elements. However, some of these variations that can now be neglected may once have had longer periods, comparable to the 'pendulum' period, if the system was formerly in deep resonance (pairs of periods even closer to the ratio 2:1 than they are now). In that case, the dynamical system cannot be reduced to fewer than nine dimensions. The nine-dimensional system is linearized here in order to study small variations about equilibrium. When tidal effects are included, the resulting evolution is substantially the same as was indicated by the pendulum approach, except that evolution out of deep resonance is found to be somewhat slower than suggested by extrapolation of the pendulum results. This slower rate helps support the hypothesis that the system may have evolved from deep resonance.

Electromagnetic energy harvesting from a dual-mass pendulum oscillator

NASA Astrophysics Data System (ADS)

Wang, Hongyan; Tang, Jiong

2016-04-01

This paper presents the analysis of a type of vibration energy harvester composed of an electromagnetic pendulum oscillator combined to an elastic main structure. In this study, the elastic main structure connected to the base is considered as a single degree-of-freedom (DOF) spring-mass-damper subsystem. The electromagnetic pendulum oscillator is considered as a dual-mass two-frequency subsystem, which is composed of a hollow bar with a tip winded coil and a magnetic mass with a spring located in the hollow bar. As the pendulum swings, the magnetic mass can move along the axial direction of the bar. Thus, the relative motion between the magnet and the coil induces a wire current. A mathematical model of the coupled system is established. The system dynamics a 1:2:1 internal resonance. Parametric analysis is carried out to demonstrate the effect of the excitation acceleration, excitation frequency, load resistance, and frequency tuning parameters on system performance.

Design and analysis of a torsion braid pendulum displacement transducer

NASA Technical Reports Server (NTRS)

Rind, E.; Bryant, E. L.

1981-01-01

The dynamic properties at various temperatures of braids impregnated with polymer can be measured by using the braid as the suspension of a torsion pendulum. This report describes the electronic and mechanical design of a torsional braid pendulum displacement transducer which is an advance in the state of the art. The transducer uses a unique optical design consisting of refracting quartz windows used in conjunction with a differential photocell to produce a null signal. The release mechanism for initiating free torsional oscillation of the pendulum has also been improved. Analysis of the precision and accuracy of the transducer indicated that the maximum relative error in measuring torsional amplitude was approximately 0. A serious problem inherent in all instruments which use a torsional suspension was analyzed: misalignment of the physical and torsional axes of the torsional member which results in modulation of the amplitude of the free oscillation.

Implementation of Push Recovery Strategy Using Triple Linear Inverted Pendulum Model in “T-FloW” Humanoid Robot

NASA Astrophysics Data System (ADS)

Dimas Pristovani, R.; Raden Sanggar, D.; Dadet, Pramadihanto.

2018-04-01

Push recovery is one of humanbehaviorwhich is a strategy to defend the body from anexternal force in any environment. This paper describes push recovery strategy which usesMIMO decoupled control system method. The dynamics system uses aquasi-dynamic system based on triple linear inverted pendulum model (TLIPM). The analysis of TLIPMuses zero moment point (ZMP) calculation from ZMP simplification in last research. By using this simplification of dynamics system, the control design can be simplified into 3 serial SISOwith known and uncertain disturbance models in each inverted pendulum. Each pendulum has different plan to damp the external force effect. In this experiment, PID controller (closed- loop)is used to arrange the damp characteristic.The experiment result shows thatwhen using push recovery control strategy (closed-loop control) is about 85.71% whilewithout using push recovery control strategy (open-loop control) it is about 28.57%.

Helicopter vibration suppression using simple pendulum absorbers on the rotor blade

NASA Technical Reports Server (NTRS)

Hamouda, M.-N. H.; Pierce, G. A.

1981-01-01

A design procedure is presented for the installation of simple pendulums on the blades of a helicopter rotor to suppress the root reactions. The procedure consists of a frequency response analysis for a hingeless rotor blade excited by a harmonic variation of spanwise airload distributions during forward flight, as well as a concentrated load at the tip. The structural modeling of the blade provides for elastic degrees of freedom in flap and lead-lag bending plus torsion. Simple flap and lead-lag pendulums are considered individually. Using a rational order scheme, the general nonlinear equations of motion are linearized. A quasi-steady aerodynamic representation is used in the formation of the airloads. The solution of the system equations derives from their representation as a transfer matrix. The results include the effect of pendulum tuning on the minimization of the hub reactions.

On the efficiency of the golf swing

NASA Astrophysics Data System (ADS)

White, Rod

2006-12-01

A non-driven double pendulum model is used to explain the principle underlying the surprising efficiency of the golf swing. The principle can be described as a parametric energy transfer between the arms and the club head due to the changing moment of inertia of the club. The transfer is a consequence of conservation of energy and angular momentum. Because the pendulum is not driven by an external force, it shows that the golfer need do little more than accelerate the arms with the wrists cocked and let the double pendulum transfer kinetic energy to the club head. A driven double pendulum model is used to study factors affecting the efficiency of a real golf swing. It is concluded that the wrist-cock angle is the most significant efficiency-determining parameter under the golfer's control and that improvements in golf technology have had a significant impact on driving distance.

Pendulum Underwater - An Approach for Quantifying Viscosity

NASA Astrophysics Data System (ADS)

Leme, José Costa; Oliveira, Agostinho

2017-12-01

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 and lightweight wire that carries a ball at its lower end, which is totally immersed in water, so as to determine the water viscosity. The system used represents a viscous damped pendulum and we tried different theoretical models to describe it. The experimental part of the present paper is based on a very simple and low-cost image capturing apparatus that can easily be replicated in a physics classroom. Data on the pendulum's amplitude as a function of time were acquired using digital video analysis with the open source software Tracker.

Mechanical characterisation of the TorPeDO: a low frequency gravitational force sensor

NASA Astrophysics Data System (ADS)

McManus, D. J.; Forsyth, P. W. F.; Yap, M. J.; Ward, R. L.; Shaddock, D. A.; McClelland, D. E.; Slagmolen, B. J. J.

2017-07-01

Newtonian noise is likely to be a future challenge at low frequencies for Advanced LIGO and other second generation gravitational wave detectors. We present the TorPeDO system: a dual torsion pendulum sensor designed to measure local gravitational forces to high precision. Gravitational forces induce a differential rotation between the two torsion beams, which is measured with an optical read-out. Both torsion pendulums have a common suspension point, tunable centre of mass, and resonant frequency. This produces a high level of mechanical common mode noise cancellation. We report on a controls prototype of the TorPeDO system, presenting the frequency response and tuning range of both pendulums. A noise budget and mechanical cross-coupling model for this system are also presented. We demonstrate frequency tuning of the two torsion pendulums to a difference of 4.3 μHz.

Investigation of Learning Behaviors and Achievement of Vocational High School Students Using an Ubiquitous Physics Tablet PC App

NASA Astrophysics Data System (ADS)

Purba, Siska Wati Dewi; Hwang, Wu-Yuin

2017-06-01

In this study, we designed and developed an app called Ubiquitous-Physics (U-Physics) for mobile devices like tablet PC or smart phones to help students learn the principles behind a simple pendulum in Physics. The unique characteristic of U-Physics is the use of sensors on mobile devices to collect acceleration and velocity data during pendulum swings. The data collected are transformed to facilitate students' understanding of the pendulum time period. U-Physics helped students understand the effects of pendulum mass, length, and angle in relation to its time period. In addition, U-Physics was equipped with an annotation function such as textual annotation to help students interpret and understand the concepts and phenomena of the simple pendulum. U-Physics also generated graphs automatically to demonstrate the time period during which the pendulum was swinging. Results showed a significant positive correlation between interpreting graphs and applying formula. This finding indicated that the ability to interpret graphs has an important role in scientific learning. Therefore, we strongly recommend that physics teachers use graphs to enrich students' information content and understanding and negative correlation between pair coherence and interpreting graphs. It may be that most of the participants (vocational high school students) have limited skill or confidence in physics problem solving; so, they often seek help from teachers or their high-achieving peers. In addition, the findings also indicated that U-Physics can enhance students' achievement during a 3-week time period. We hope that this app can be globally used to learn physics in the future.

Intermittent Feedback-Control Strategy for Stabilizing Inverted Pendulum on Manually Controlled Cart as Analogy to Human Stick Balancing

PubMed Central

Yoshikawa, Naoya; Suzuki, Yasuyuki; Kiyono, Ken; Nomura, Taishin

2016-01-01

The stabilization of an inverted pendulum on a manually controlled cart (cart-inverted-pendulum; CIP) in an upright position, which is analogous to balancing a stick on a fingertip, is considered in order to investigate how the human central nervous system (CNS) stabilizes unstable dynamics due to mechanical instability and time delays in neural feedback control. We explore the possibility that a type of intermittent time-delayed feedback control, which has been proposed for human postural control during quiet standing, is also a promising strategy for the CIP task and stick balancing on a fingertip. Such a strategy hypothesizes that the CNS exploits transient contracting dynamics along a stable manifold of a saddle-type unstable upright equilibrium of the inverted pendulum in the absence of control by inactivating neural feedback control intermittently for compensating delay-induced instability. To this end, the motions of a CIP stabilized by human subjects were experimentally acquired, and computational models of the system were employed to characterize the experimental behaviors. We first confirmed fat-tailed non-Gaussian temporal fluctuation in the acceleration distribution of the pendulum, as well as the power-law distributions of corrective cart movements for skilled subjects, which was previously reported for stick balancing. We then showed that the experimental behaviors could be better described by the models with an intermittent delayed feedback controller than by those with the conventional continuous delayed feedback controller, suggesting that the human CNS stabilizes the upright posture of the pendulum by utilizing the intermittent delayed feedback-control strategy. PMID:27148031

The frequency of human, manual adjustments in balancing an inverted pendulum is constrained by intrinsic physiological factors

PubMed Central

Loram, Ian D; Gawthrop, Peter J; Lakie, Martin

2006-01-01

While standing naturally and when manually or pedally balancing an equivalent inverted pendulum, the load sways slowly (characteristic unidirectional duration ∼1 s) and the controller, calf muscles or hand, makes more frequent adjustments (characteristic unidirectional duration 400 ms). Here we test the hypothesis that these durations reflect load properties rather than some intrinsic property of the human neuromuscular system. Using a specialized set-up mechanically analogous to real standing, subjects manually balanced inverted pendulums with different moments of inertia through a compliant spring representing the Achilles tendon. The spring bias was controlled by a sensitive joystick via a servo motor and accurate visual feedback was provided on an oscilloscope. As moment of inertia decreased, inverted pendulum sway size increased and it became difficult to sustain successful balance. The mean duration of unidirectional balance adjustments did not change. Moreover, the mean duration of unidirectional inverted pendulum sway reduced only slightly, remaining around 1 s. The simplest explanation is that balance was maintained by a process of manual adjustments intrinsically limited to a mean frequency of two to three unidirectional adjustments per second corresponding to intermittent control observed in manual tracking experiments. Consequently the inverted pendulum sway duration, mechanically related to the bias duration, reflects an intrinsic constraint of the neuromuscular control system. Given the similar durations of sway and muscle adjustments observed in real standing, we postulate that the characteristic duration of unidirectional standing sway reflects intrinsic intermittent control rather than the inertial properties of the body. PMID:16973712

Intermittent Feedback-Control Strategy for Stabilizing Inverted Pendulum on Manually Controlled Cart as Analogy to Human Stick Balancing.

PubMed

Yoshikawa, Naoya; Suzuki, Yasuyuki; Kiyono, Ken; Nomura, Taishin

2016-01-01

The stabilization of an inverted pendulum on a manually controlled cart (cart-inverted-pendulum; CIP) in an upright position, which is analogous to balancing a stick on a fingertip, is considered in order to investigate how the human central nervous system (CNS) stabilizes unstable dynamics due to mechanical instability and time delays in neural feedback control. We explore the possibility that a type of intermittent time-delayed feedback control, which has been proposed for human postural control during quiet standing, is also a promising strategy for the CIP task and stick balancing on a fingertip. Such a strategy hypothesizes that the CNS exploits transient contracting dynamics along a stable manifold of a saddle-type unstable upright equilibrium of the inverted pendulum in the absence of control by inactivating neural feedback control intermittently for compensating delay-induced instability. To this end, the motions of a CIP stabilized by human subjects were experimentally acquired, and computational models of the system were employed to characterize the experimental behaviors. We first confirmed fat-tailed non-Gaussian temporal fluctuation in the acceleration distribution of the pendulum, as well as the power-law distributions of corrective cart movements for skilled subjects, which was previously reported for stick balancing. We then showed that the experimental behaviors could be better described by the models with an intermittent delayed feedback controller than by those with the conventional continuous delayed feedback controller, suggesting that the human CNS stabilizes the upright posture of the pendulum by utilizing the intermittent delayed feedback-control strategy.

Human balancing of an inverted pendulum with a compliant linkage: neural control by anticipatory intermittent bias

PubMed Central

Lakie, Martin; Caplan, Nicholas; Loram, Ian D

2003-01-01

These experiments were prompted by the recent discovery that the intrinsic stiffness of the ankle is inadequate to stabilise passively the body in standing. Our hope was that showing how a large inverted pendulum was manually balanced with low intrinsic stiffness would elucidate the active control of human standing. The results show that the pendulum can be satisfactorily stabilised when intrinsic stiffness is low. Analysis of sway size shows that intrinsic stiffness actually plays little part in stabilisation. The sway duration is also substantially independent of intrinsic stiffness. This suggests that the characteristic sway of the pendulum, rather than being dictated by stiffness and inertia, may result from the control pattern of hand movements. The key points revealed by these experiments are that with low intrinsic stiffness the hand provides pendulum stability by intermittently altering the bias of the spring and, on average, the hand moves in opposition to the load. The results lead to a new and testable hypothesis; namely that in standing, the calf muscle shortens as the body sways forward and lengthens as it sways backwards. These findings are difficult to reconcile with stretch reflex control of the pendulum and are of particular relevance to standing. They may also be relevant to postural maintenance in general whenever the CNS controls muscles which operate through compliant linkages. The results also suggest that in standing, rather than providing passive stability, the intrinsic stiffness acts as an energy efficient buffer which provides decoupling between muscle and body. PMID:12832494

[Evaluation of pendulum testing of spasticity].

PubMed

Le Cavorzin, P; Hernot, X; Bartier, O; Carrault, G; Chagneau, F; Gallien, P; Allain, H; Rochcongar, P

2002-11-01

To identify valid measurements of spasticity derived from the pendulum test of the leg in a representative population of spastic patients. Pendulum testing was performed in 15 spastic and 10 matched healthy subjects. The reflex-mediated torque evoked in quadriceps femoris, as well as muscle mechanical parameters (viscosity and elasticity), were calculated using mathematical modelling. Correlation with the two main measures derived from the pendulum test reported in the literature (the Relaxation Index and the area under the curve) was calculated in order to select the most valid. Among mechanical parameters, only viscosity was found to be significantly higher in the spastic group. As expected, the computed integral of the reflex-mediated torque was found to be larger in spastics than in healthy subjects. A significant non-linear (logarithmic) correlation was found between the clinically-assessed muscle spasticity (Ashworth grading) and the computed reflex-mediated torque, emphasising the non-linear behaviour of this scale. Among measurements derived from the pendulum test which are proposed in the literature for routine estimation of spasticity, the Relaxation Index exhibited an unsuitable U-shaped pattern of variation with increasing reflex-mediated torque. On the opposite, the area under the curve revealed a linear regression, which is more convenient for routine estimation of spasticity. The pendulum test of the leg is a simple technique for the assessment of spastic hypertonia. However, the measurement generally used in the literature (the Relaxation Index) exhibits serious limitations, and would benefit to be replaced by more valid measures, such as the area under the goniometric curve, especially for the assessment of therapeutics.

9. BUILDING NO. 620B, FRICTION PENDULUM BUILDING. 29FOOT DROP TOWER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. BUILDING NO. 620-B, FRICTION PENDULUM BUILDING. 29-FOOT DROP TOWER SITS BEHIND BLAST SHIELD IN FRONT OF BUILDING. - Picatinny Arsenal, 600 Area, Test Areas District, State Route 15 near I-80, Dover, Morris County, NJ

Acceleration of neutrons in a scheme of a tautochronous mathematical pendulum (physical principles)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivlin, Lev A

We consider the physical principles of neutron acceleration through a multiple synchronous interaction with a gradient rf magnetic field in a scheme of a tautochronous mathematical pendulum. (laser applications and other aspects of quantum electronics)

The Slinky Wilberforce pendulum: A simple coupled oscillator

NASA Astrophysics Data System (ADS)

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.

The Impact of Pictorial Display on Operator Learning and Performance. M.S. Thesis

NASA Technical Reports Server (NTRS)

Miller, R. A.; Messing, L. J.; Jagacinski, R. J.

1984-01-01

The effects of pictorially displayed information on human learning and performance of a simple control task were investigated. The controlled system was a harmonic oscillator and the system response was displayed to subjects as either an animated pendulum or a horizontally moving dot. Results indicated that the pendulum display did not effect performance scores but did significantly effect the learning processes of individual operators. The subjects with the pendulum display demonstrated more vertical internal models early in the experiment and the manner in which their internal models were tuned with practice showed increased variability between subjects.

Magnetic shielding in a low temperature torsion pendulum experiment. [superconducting cylinders for attenuation earth field

NASA Technical Reports Server (NTRS)

Phillips, P. R.

1979-01-01

A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature, so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 0.0001 G while simultaneously the moment of the magnet can be reduced by a factor 7 x 10 to the 4th.

Dynamic modelling of a double-pendulum gantry crane system incorporating payload

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, R. M. T. Raja; Ahmad, M. A.; Ramli, M. S.

The natural sway of crane payloads is detrimental to safe and efficient operation. Under certain conditions, the problem is complicated when the payloads create a double pendulum effect. This paper presents dynamic modelling of a double-pendulum gantry crane system based on closed-form equations of motion. The Lagrangian method is used to derive the dynamic model of the system. A dynamic model of the system incorporating payload is developed and the effects of payload on the response of the system are discussed. Extensive results that validate the theoretical derivation are presented in the time and frequency domains.

Non-extraction treatment of severe crowding with pendulum appliance.

PubMed

Gandikota, Chandrasekhar; Venkata, Yudhister Palla; Challa, Padmalatha; Juvvadi, Shubhaker Rao

2013-07-01

An extraction case was planned for non-extraction treatment using pendulum appliance and the effect of appliance was evaluated in a 14-year-old girl with a severe maxillary and mandibular crowding followed by non-extraction fixed appliance preadjusted edgewise appliance mechanotherapy. Total treatment time was for 22 months. The obtuse nasolabial angle was maintained intact. Correction of crowding, co-ordinated arch forms was achieved with molar distalization. The impetus on soft-tissue paradigm is stressed in this case report and pendulum appliance can indeed boost our clinical acumen and swing our priorities toward non-extraction treatment.

What Makes the Foucault Pendulum Move among the Stars?

NASA Astrophysics Data System (ADS)

Phillips, Norman

2004-11-01

Foucault's pendulum exhibition in 1851 occurred in an era now known by development of the theorems of Coriolis and the formulation of dynamical meteorology by Ferrel. Yet today the behavior of the pendulum is often misunderstood. The existence of a horizontal component of Newtonian gravitation is essential for understanding the behavior with respect to the stars. Two simple mechanical principles describe why the path of oscillation is fixed only at the poles; the principle of centripetal acceleration and the principle of conservation of angular momentum. A sky map is used to describe the elegant path among the stars produced by these principles.

Long period nodal motion of sun synchronous orbits

NASA Technical Reports Server (NTRS)

Duck, K. I.

1975-01-01

An approximative model is formulated for assessing these perturbations that significantly affect long term modal motion of sun synchronous orbits. Computer simulations with several independent computer programs consider zonal and tesseral gravitational harmonics, third body gravitational disturbances induced by the sun and the moon, and atmospheric drag. A pendulum model consisting of evenzonal harmonics through order 4 and solar gravity dominated nodal motion approximation. This pendulum motion results from solar gravity inducing an inclination oscillation which couples into the nodal precession induced by the earth's oblateness. The pendulum model correlated well with simulations observed flight data.

Determination of the Optimal Position of Pendulums of an Active Self-balancing Device

NASA Astrophysics Data System (ADS)

Ziyakaev, G. R.; Kazakova, O. A.; Yankov, V. V.; Ivkina, O. P.

2017-04-01

The demand of the modern manufacturing industry for machines with high motion speed leads to increased load and vibration activity of the main elements of rotor systems. Vibration reduces operating life of bearings, has adversary effects on human organism, and can cause accidents. One way to compensate for a rotating rotor's imbalance is the use of active self-balancing devices. The aim of this work is to determine the position of their pendulums, in which the imbalance is minimized. As a result of the study, a formula for determining the angle of the pendulums was obtained.

The anisosphere as a new tool for interpreting Foucault pendulum experiments. Part I: harmonic oscillators

NASA Astrophysics Data System (ADS)

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.

Orion Multi-Purpose Crew Vehicle Solving and Mitigating the Two Main Cluster Pendulum Problem

NASA Technical Reports Server (NTRS)

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.

Technical strategy of triple jump: differences of inverted pendulum model between hop-dominated and balance techniques.

PubMed

Fujibayashi, Nobuaki; Otsuka, Mitsuo; Yoshioka, Shinsuke; Isaka, Tadao

2017-10-24

The present study aims to cross-sectionally clarify the characteristics of the motions of an inverted pendulum model, a stance leg, a swing leg and arms in different triple-jumping techniques to understand whether or not hop displacement is relatively longer rather than step and jump displacements. Eighteen male athletes performed the triple jump with a full run-up. Based on the technique of the jumpers, they were classified as hop-dominated (n = 10) or balance (n = 8) jumpers. The kinematic data were calculated using motion capture and compared between the two techniques using the inverted pendulum model. The hop-dominated jumpers had a significantly longer hop displacement and faster vertical centre-of-mass (COM) velocity of their whole body at hop take-off, which was generated by faster rotation behaviours of inverted pendulum model and faster swinging behaviours of arms. Conversely, balance jumpers had a significantly longer jump displacement and faster horizontal COM velocity of their whole body at take-off, which was generated by a stiffer inverted pendulum model and stance leg. The results demonstrate that hop-dominated and balance jumpers enhanced each dominated-jump displacement using different swing- and stance-leg motions. This information may help to enhance the actual displacement of triple jumpers using different jumping techniques.

Interpreting lateral dynamic weight shifts using a simple inverted pendulum model.

PubMed

Kennedy, Michael W; Bretl, Timothy; Schmiedeler, James P

2014-01-01

Seventy-five young, healthy adults completed a lateral weight-shifting activity in which each shifted his/her center of pressure (CoP) to visually displayed target locations with the aid of visual CoP feedback. Each subject's CoP data were modeled using a single-link inverted pendulum system with a spring-damper at the joint. This extends the simple inverted pendulum model of static balance in the sagittal plane to lateral weight-shifting balance. The model controlled pendulum angle using PD control and a ramp setpoint trajectory, and weight-shifting was characterized by both shift speed and a non-minimum phase (NMP) behavior metric. This NMP behavior metric examines the force magnitude at shift initiation and provides weight-shifting balance performance information that parallels the examination of peak ground reaction forces in gait analysis. Control parameters were optimized on a subject-by-subject basis to match balance metrics for modeled results to metric values calculated from experimental data. Overall, the model matches experimental data well (average percent error of 0.35% for shifting speed and 0.05% for NMP behavior). These results suggest that the single-link inverted pendulum model can be used effectively to capture lateral weight-shifting balance, as it has been shown to model static balance. Copyright © 2014 Elsevier B.V. All rights reserved.

Decoupling the structure from the ground motion during earthquakes by employing friction pendulums

NASA Astrophysics Data System (ADS)

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.

Acceleration control system for semi-active in-car crib with joint application of regular and inverted pendulum mechanisms

NASA Astrophysics Data System (ADS)

Kawashima, T.

2016-09-01

To reduce the risk of injury to an infant in an in-car crib (or in a child safety bed) collision shock during a car crash, it is necessary to maintain a constant force acting on the crib below a certain allowable value. To realize this objective, we propose a semi-active in-car crib system with the joint application of regular and inverted pendulum mechanisms. The arms of the proposed crib system support the crib like a pendulum while the pendulum system itself is supported like an inverted pendulum by the arms. In addition, the friction torque of each arm is controlled using a brake mechanism that enables the proposed in-car crib to decrease the acceleration of the crib gradually and maintain it around the target value. This system not only reduces the impulsive force but also transfers the force to the infant's back using a spin control system, i.e., the impulse force acts is made to act perpendicularly on the crib. The spin control system was developed in our previous work. This work focuses on the acceleration control system. A semi-active control law with acceleration feedback is introduced, and the effectiveness of the system is demonstrated using numerical simulation and model experiment.

A method for the determination of the coefficient of rolling friction using cycloidal pendulum

NASA Astrophysics Data System (ADS)

Ciornei, M. C.; Alaci, S.; Ciornei, F. C.; Romanu, I. C.

2017-08-01

The paper presents a method for experimental finding of coefficient of rolling friction appropriate for biomedical applications based on the theory of cycloidal pendulum. When a mobile circle rolls over a fixed straight line, the points from the circle describe trajectories called normal cycloids. To materialize this model, it is sufficient that a small region from boundary surfaces of a moving rigid body is spherical. Assuming pure rolling motion, the equation of motion of the cycloidal pendulum is obtained - an ordinary nonlinear differential equation. The experimental device is composed by two interconnected balls rolling over the material to be studied. The inertial characteristics of the pendulum can be adjusted via weights placed on a rod. A laser spot oscillates together to the pendulum and provides the amplitude of oscillations. After finding the experimental parameters necessary in differential equation of motion, it can be integrated using the Runge-Kutta of fourth order method. The equation was integrated for several materials and found values of rolling friction coefficients. Two main conclusions are drawn: the coefficient of rolling friction influenced significantly the amplitude of oscillation but the effect upon the period of oscillation is practically imperceptible. A methodology is proposed for finding the rolling friction coefficient and the pure rolling condition is verified.

Dynamics of quiet human stance: computer simulations of a triple inverted pendulum model.

PubMed

Günther, Michael; Wagner, Heiko

2016-01-01

For decades, the biomechanical description of quiet human stance has been dominated by the single inverted pendulum (SIP) paradigm. However, in the past few years, the SIP model family has been falsified as an explanatory approach. Double inverted pendulum models have recently proven to be inappropriate. Human topology with three major leg joints suggests in a natural way to examine triple inverted pendulum (TIP) models as an appropriate approach. In this study, we focused on formulating a TIP model that can synthesise stable balancing attractors based on minimalistic sensor information and actuation complexity. The simulated TIP oscillation amplitudes are realistic in vertical direction. Along with the horizontal ankle, knee and hip positions, though, all simulated joint angle amplitudes still exceed the measured ones about threefold. It is likely that they could be eventually brought down to the physiological range by using more sensor information. The TIP systems' eigenfrequency spectra come out as another major result. The eigenfrequencies spread across about 0.1 Hz...20 Hz. Our main result is that joint stiffnesses can be reduced even below statically required values by using an active hip torque balancing strategy. When reducing mono- and bi-articular stiffnesses further down to levels threatening dynamic stability, the spectra indicate a change from torus-like (stable) to strange (chaotic) attractors. Spectra of measured ground reaction forces appear to be strange-attractor-like. We would conclude that TIP models are a suitable starting point to examine more deeply the dynamic character of and the essential structural properties behind quiet human stance. Abbreviations and technical terms Inverted pendulum body exposed to gravity and pivoting in a joint around position of unstable equilibrium (operating point) SIP single inverted pendulum: one rigid body pivoting around fixation to the ground (external joint) DIP double inverted pendulum: two bodies; external and internal joint operate around instability TIP triple inverted pendulum: three bodies; external and both internal joints operate around instability QIP quadruple inverted pendulum: four bodies, foot replaces external joint; all three internal joints operate around instability Eigenfrequency characteristic frequency that a physical system is oscillating at when externally excited at a limited energy level DOF degree of freedom; in mechanics: linear displacement or angle or combination thereof Mono-articular stiffness: coefficient of proportionality between mechanical displacement of a DOF and restoring force/torque component in the respective DOF Bi-articular stiffness coefficient of proportionality between mechanical displacement of a DOF and restoring force/torque component in another DOF GRF ground reaction force HAT segment including head, arms and trunk COM centre of mass COP centre of pressure in the plane of the force platform surface.

Apparatus for Teaching Physics: A Very Short, Portable Foucault Pendulum.

ERIC Educational Resources Information Center

Kruglak, Haym

1983-01-01

Describes the construction of a small (portable), inexpensive, and easy to build Foucault pendulum. Includes photographs of the apparatus, a schematic of the electrical circuit used, and discussion of the amount of accuracy to be expected during classroom investigation. (JM)

Viscous-pendulum damper suppresses structural vibrations

NASA Technical Reports Server (NTRS)

Reed, W. H., III

1964-01-01

The viscous pendulum damper consists of a cylinder containing round trays on which round lead slugs rest. When assembled, the container is filled with a viscous liquid and attached, with axis vertical, to the structure. The device permits varying the damping of structural vibrations.

29 CFR Appendix E to Subpart M of... - Sample Fall Protection Plan

Code of Federal Regulations, 2014 CFR

2014-07-01

... edge of the floor or beam and swing the worker like a pendulum until the line has moved to a position... points. Accompanying this pendulum swing is a lowering of the worker, with the attendant danger that he...

Science Projects from Astronomy to Zoology.

ERIC Educational Resources Information Center

Learning, 1983

1983-01-01

Activities for teaching about the solar system, the earth's rotation, plants, pendulums, and animal adaptation are described. Included are suggestions for building scale models to illustrate the solar system's proportions and the earth's rotation speed, and for using playground swings to demonstrate pendulum motion. (PP)

75 FR 19895 - Final Flood Elevation Determinations

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-16

... +1529 Eastern Band of Cherokee Hanging Dog Creek. Indians, Unincorporated Areas of Cherokee County. Approximately 0.8 mile +1633 upstream of the confluence with Hanging Dog Creek. Big Witch Creek At the.... Indians. Approximately 1,050 feet +1904 upstream of Goose Creek Road. Hanging Dog Creek At the confluence...

Axisymmetric Liquid Hanging Drops

ERIC Educational Resources Information Center

Meister, Erich C.; Latychevskaia, Tatiana Yu

2006-01-01

The geometry of drops hanging on a circular capillary can be determined by numerically solving a dimensionless differential equation that is independent on any material properties, which enables one to follow the change of the height, surface area, and contact angle of drops hanging on a particular capillary. The results show that the application…

Learning an Intermittent Control Strategy for Postural Balancing Using an EMG-Based Human-Computer Interface

PubMed Central

Asai, Yoshiyuki; Tateyama, Shota; Nomura, Taishin

2013-01-01

It has been considered that the brain stabilizes unstable body dynamics by regulating co-activation levels of antagonist muscles. Here we critically reexamined this established theory of impedance control in a postural balancing task using a novel EMG-based human-computer interface, in which subjects were asked to balance a virtual inverted pendulum using visual feedback information on the pendulum's position. The pendulum was actuated by a pair of antagonist joint torques determined in real-time by activations of the corresponding pair of antagonist ankle muscles of subjects standing upright. This motor-task raises a frustrated environment; a large feedback time delay in the sensorimotor loop, as a source of instability, might favor adopting the non-reactive, preprogrammed impedance control, but the ankle muscles are relatively hard to co-activate, which hinders subjects from adopting the impedance control. This study aimed at discovering how experimental subjects resolved this frustrated environment through motor learning. One third of subjects adapted to the balancing task in a way of the impedance-like control. It was remarkable, however, that the majority of subjects did not adopt the impedance control. Instead, they acquired a smart and energetically efficient strategy, in which two muscles were inactivated simultaneously at a sequence of optimal timings, leading to intermittent appearance of periods of time during which the pendulum was not actively actuated. Characterizations of muscle inactivations and the pendulum¡Çs sway showed that the strategy adopted by those subjects was a type of intermittent control that utilizes a stable manifold of saddle-type unstable upright equilibrium that appeared in the state space of the pendulum when the active actuation was turned off. PMID:23717398

Common Cause Case Study: An Estimated Probability of Four Solid Rocket Booster Hold-down Post Stud Hang-ups

NASA Technical Reports Server (NTRS)

Cross, Robert

2005-01-01

Until Solid Rocket Motor ignition, the Space Shuttle is mated to the Mobil Launch Platform in part via eight (8) Solid Rocket Booster (SRB) hold-down bolts. The bolts are fractured using redundant pyrotechnics, and are designed to drop through a hold-down post on the Mobile Launch Platform before the Space Shuttle begins movement. The Space Shuttle program has experienced numerous failures where a bolt has "hung-up." That is, it did not clear the hold-down post before liftoff and was caught by the SRBs. This places an additional structural load on the vehicle that was not included in the original certification requirements. The Space Shuttle is currently being certified to withstand the loads induced by up to three (3) of eight (8) SRB hold-down post studs experiencing a "hang-up." The results af loads analyses performed for four (4) stud-hang ups indicate that the internal vehicle loads exceed current structural certification limits at several locations. To determine the risk to the vehicle from four (4) stud hang-ups, the likelihood of the scenario occurring must first be evaluated. Prior to the analysis discussed in this paper, the likelihood of occurrence had been estimated assuming that the stud hang-ups were completely independent events. That is, it was assumed that no common causes or factors existed between the individual stud hang-up events. A review of the data associated with the hang-up events, showed that a common factor (timing skew) was present. This paper summarizes a revised likelihood evaluation performed for the four (4) stud hang-ups case considering that there are common factors associated with the stud hang-ups. The results show that explicitly (i.e. not using standard common cause methodologies such as beta factor or Multiple Greek Letter modeling) taking into account the common factor of timing skew results in an increase in the estimated likelihood of four (4) stud hang-ups of an order of magnitude over the independent failure case.

Common Cause Case Study: An Estimated Probability of Four Solid Rocket Booster Hold-Down Post Stud Hang-ups

NASA Technical Reports Server (NTRS)

Cross, Robert

2005-01-01

Until Solid Rocket Motor ignition, the Space Shuttle is mated to the Mobil Launch Platform in part via eight (8) Solid Rocket Booster (SRB) hold-down bolts. The bolts are fractured using redundant pyrotechnics, and are designed to drop through a hold-down post on the Mobile Launch Platform before the Space Shuttle begins movement. The Space Shuttle program has experienced numerous failures where a bolt has hung up. That is, it did not clear the hold-down post before liftoff and was caught by the SRBs. This places an additional structural load on the vehicle that was not included in the original certification requirements. The Space Shuttle is currently being certified to withstand the loads induced by up to three (3) of eight (8) SRB hold-down experiencing a "hang-up". The results of loads analyses performed for (4) stud hang-ups indicate that the internal vehicle loads exceed current structural certification limits at several locations. To determine the risk to the vehicle from four (4) stud hang-ups, the likelihood of the scenario occurring must first be evaluated. Prior to the analysis discussed in this paper, the likelihood of occurrence had been estimated assuming that the stud hang-ups were completely independent events. That is, it was assumed that no common causes or factors existed between the individual stud hang-up events. A review of the data associated with the hang-up events, showed that a common factor (timing skew) was present. This paper summarizes a revised likelihood evaluation performed for the four (4) stud hang-ups case considering that there are common factors associated with the stud hang-ups. The results show that explicitly (i.e. not using standard common cause methodologies such as beta factor or Multiple Greek Letter modeling) taking into account the common factor of timing skew results in an increase in the estimated likelihood of four (4) stud hang-ups of an order of magnitude over the independent failure case.

The Effect of Single or Repeated Home Visits on the Hanging and Use of Insecticide-Treated Mosquito Nets following a Mass Distribution Campaign - A Cluster Randomized, Controlled Trial

PubMed Central

Kilian, Albert; Balayo, Connie; Feldman, Mitra; Koenker, Hannah; Lokko, Kojo; Ashton, Ruth A.; Bruce, Jane; Lynch, Matthew; Boulay, Marc

2015-01-01

Background Study objective was to evaluate the effectiveness of commonly used post-campaign hang-up visits on the hanging and use of campaign nets. Methods A cluster-randomized trial was carried out in Uganda following an ITN distribution campaign. Five clusters (parishes, consisting of ∼11 villages each) were randomly selected for each of the three study arms with between 7,534 and 9,401 households per arm. Arm 1 received one hang-up visit, while Arm 2 received two visits by volunteers four and seven months after the campaign. Visits consisted of assistance hanging the net and education on net use. The control arm was only exposed to messages during the campaign itself. Three cross-sectional surveys with a two-stage cluster sampling design, representative of the study populations, were carried out to capture the two key outcome variables of net hanging and ITN use. Sample size was calculated to detect at least a 15 percentage-points change in net use, and was 1811 at endline. The analysis used an intention-to-treat approach. Findings Both hanging and use of ITN increased during follow-up in a similar way in all three study arms. The proportion of the population using an ITN the previous night was 64.0% (95% CI 60.8, 67.2), for one additional visit, 68.2% (63.8, 72.2) for two visits and 64.0% (59.4, 68.5) for the control. The proportion of households with all campaign nets hanging increased from 55.7% to 72.5% at endline (p<0.0005 for trend), with no difference between study arms. Financial cost per household visited was estimated as USD 2.33 for the first visit and USD 2.24 for the second. Conclusions Behavior change communication provided during the campaign or through other channels was sufficient to induce high levels of net hanging and use and additional “hang-up” activities were not cost-effective. PMID:25774676

Evaluation of a universal long-lasting insecticidal net (LLIN) distribution campaign in Ghana: cost effectiveness of distribution and hang-up activities

PubMed Central

2014-01-01

Background Between May 2010 and October 2012, approximately 12.5 million long-lasting insecticidal nets (LLINs) were distributed through a national universal mass distribution campaign in Ghana. The campaign included pre-registration of persons and sleeping places, door-to-door distribution of LLINs with ‘hang-up’ activities by volunteers and post-distribution ‘keep-up’ behaviour change communication activities. Hang-up activities were included to encourage high and sustained use. Methods The cost and cost-effectiveness of the LLIN Campaign were evaluated using a before-after design in three regions: Brong Ahafo, Central and Western. The incremental cost effectiveness of the ‘hang-up’ component was estimated using reported variation in the implementation of hang-up activities and LLIN use. Economic costs were estimated from a societal perspective assuming LLINs would be replaced after three years, and included the time of unpaid volunteers and household contributions given to volunteers. Results Across the three regions, 3.6 million campaign LLINs were distributed, and 45.5% of households reported the LLINs received were hung-up by a volunteer. The financial cost of the campaign was USD 6.51 per LLIN delivered. The average annual economic cost was USD 2.90 per LLIN delivered and USD 6,619 per additional child death averted by the campaign. The cost-effectiveness of the campaign was sensitive to the price, lifespan and protective efficacy of LLINs. Hang-up activities constituted 7% of the annual economic cost, though the additional financial cost was modest given the use of volunteers. LLIN use was greater in households in which one or more campaign LLINs were hung by a volunteer (OR = 1.57; 95% CI = 1.09, 2.27; p = 0.02). The additional economic cost of the hang-up activities was USD 0.23 per LLIN delivered, and achieved a net saving per LLIN used and per death averted. Conclusion In this campaign, hang-up activities were estimated to be net saving if hang-up increased LLIN use by 10% or more. This suggests hang-up activities can make a LLIN campaign more cost-effective. PMID:24581249

LETTERS AND COMMENTS: Note on the 'log formulae' for pendulum motion valid for any amplitude

NASA Astrophysics Data System (ADS)

Qing-Xin, Yuan; Pei, Ding

2010-01-01

In this note, we present an improved approximation to the solution of Lima (2008 Eur. J. Phys. 29 1091), which decreases the maximum relative error from 0.6% to 0.084% in evaluating the exact pendulum period.

Extraordinary Oscillations of an Ordinary Forced Pendulum

ERIC Educational Resources Information Center

Butikov, Eugene I.

2008-01-01

Several well-known and newly discovered counterintuitive regular and chaotic modes of the sinusoidally driven rigid planar pendulum are discussed and illustrated by computer simulations. The software supporting the investigation offers many interesting predefined examples that demonstrate various peculiarities of this famous physical model.…

Linear active disturbance rejection control of underactuated systems: the case of the Furuta pendulum.

PubMed

Ramírez-Neria, M; Sira-Ramírez, H; Garrido-Moctezuma, R; Luviano-Juárez, A

2014-07-01

An Active Disturbance Rejection Control (ADRC) scheme is proposed for a trajectory tracking problem defined on a nonfeedback linearizable Furuta Pendulum example. A desired rest to rest angular position reference trajectory is to be tracked by the horizontal arm while the unactuated vertical pendulum arm stays around its unstable vertical position without falling down during the entire maneuver and long after it concludes. A linear observer-based linear controller of the ADRC type is designed on the basis of the flat tangent linearization of the system around an arbitrary equilibrium. The advantageous combination of flatness and the ADRC method makes it possible to on-line estimate and cancels the undesirable effects of the higher order nonlinearities disregarded by the linearization. These effects are triggered by fast horizontal arm tracking maneuvers driving the pendulum substantially away from the initial equilibrium point. Convincing experimental results, including a comparative test with a sliding mode controller, are presented. © 2013 ISA. Published by ISA. All rights reserved.

Changes consequent to maxillary molar distalization with the bone-anchored pendulum appliance.

PubMed

Cambiano, Aldo Otazú; Janson, Guilherme; Fuziy, Acácio; Garib, Daniela Gamba; Lorenzoni, Diego Coelho

2017-01-01

This retrospective study aimed to evaluate the dentoalveolar, skeletal, and soft tissue effects obtained with bone-anchored pendulum appliance in patients with Class II malocclusion. A total of 18 patients (4 male, 14 female) at a mean pretreatment age of 14.0 years (+1.08) were enrolled in this study. All patients were treated with the bone-anchored pendulum appliance for an average duration of 4.8 months. Only the active distalization period was evaluated with predistalization and postdistalization lateral cephalograms. Skeletal, dentoalveolar, and soft tissue variables were obtained. Based on these variables, the treatment effects were evaluated with dependent t -test. Correction of Class II molar relationship resulted from distal movement of 3.45 mm and tipping of 11.24° of the first maxillary molars. The premolars were distalized accompanying the molars. The bone-anchored pendulum appliance proved to be an effective method for distalization of maxillary molars in cases that require maximum anchorage, avoiding reciprocal mesial movement of premolars and incisors.

Influence of Partial Solar Eclipse 2016 on the surface gravity acceleration using photogate sensor on Kater's reversible pendulum

NASA Astrophysics Data System (ADS)

Nugraha, M. G.; Saepuzaman, D.; Sholihat, F. N.; Ramayanti, S.; Setyadin, A. H.; Ferahenki, A. R.; Samsudin, A.; Utama, J. A.; Susanti, H.; Kirana, K. H.

2016-11-01

This study was conducted to determine the Earth's surface gravitational acceleration (g) prior to, during, and after a partial solar eclipse. Data was collected in Basic Physics Laboratory Universitas Pendidikan Indonesia, Bandung with coordinates S 6°51'48", E 107°35'40" for three days on March 8 - 10, 2016, in time interval measurement from 6 a.m. to 9 a.m. This research used a standard pendulum, Kater's reversible pendulum, which deviated less than 3° so that the motion can be regarded harmonics oscillation. The period of pendulum oscillation motion is measured by a light sensor (photogate sensor) with accuracy until 10-13 seconds. The data analysis shows that there is small difference value of gravity acceleration at the Earth's surface from three days of observation, i.e. in the order of 10-3 ms-2. It means, there is a changes in the Earth's surface gravitational acceleration (g) due to the partial solar eclipse but not significant.

Estimating and Comparing Dam Deformation Using Classical and GNSS Techniques.

PubMed

Barzaghi, Riccardo; Cazzaniga, Noemi Emanuela; De Gaetani, Carlo Iapige; Pinto, Livio; Tornatore, Vincenza

2018-03-02

Global Navigation Satellite Systems (GNSS) receivers are nowadays commonly used in monitoring applications, e.g., in estimating crustal and infrastructure displacements. This is basically due to the recent improvements in GNSS instruments and methodologies that allow high-precision positioning, 24 h availability and semiautomatic data processing. In this paper, GNSS-estimated displacements on a dam structure have been analyzed and compared with pendulum data. This study has been carried out for the Eleonora D'Arborea (Cantoniera) dam, which is in Sardinia. Time series of pendulum and GNSS over a time span of 2.5 years have been aligned so as to be comparable. Analytical models fitting these time series have been estimated and compared. Those models were able to properly fit pendulum data and GNSS data, with standard deviation of residuals smaller than one millimeter. These encouraging results led to the conclusion that GNSS technique can be profitably applied to dam monitoring allowing a denser description, both in space and time, of the dam displacements than the one based on pendulum observations.

PETER: A Hardware Simulator for the Test Mass-GRS System of LISA Pathfinder

NASA Astrophysics Data System (ADS)

Marconi, L.; Stanga, R.; Bassan, M.; De Marchi, F.; Pucacco, G.; Visco, M.; Di Fiore, L.; De Rosa, R.; Garufi, F.

2013-01-01

Each LISA PathFinder test mass (TM) will be sensitive to forces along all its 6 Degrees of Freedom (DoFs). Extensive ground testing is required in order to evaluate the influence of cross-talks from the read-out and actuator channels. In the INFN laboratory of Firenze we have developed a facility for a good representation of the free fall conditions of the TM on flight. A hollow replica of a TM hanging from a double torsion pendulum can move inside a Gravitational Reference Sensor (GRS) with quasi free fall condition on two Dofs, in the frequency band (0.1 ÷ 100)mHz. On both DoFs, the target residual accelerations (yet to be achieved) at the low end frequency range are ≤ 3 × 10-13ms-2, limited by the thermal noise of the fibres. At higher frequencies, the sensitivity is limited by the readout noise of the readout, a replica of the flight electronics. After a long commissioning, we are now in operating conditions, and can carry out a series of experiments to better qualify the interaction between TM and GRS. In this paper we will show some significant qualification measurements and a first scientific measurements, i.e. the measurement and compensation of the DC bias in the GRS using two independent channels, as well as a measurement of the residual acceleration of the translational DoF, with the feedback loop closed on the rotational one, and viceversa.

Thrust Stand for Electric Propulsion Performance Evaluation

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.; Dehoyos, Amado; Spaun, Benjamin

2006-01-01

An electric propulsion thrust stand capable of supporting testing of thrusters having a total mass of up to 125 kg and producing thrust levels between 100 microN to 1 N has been developed and tested. The design features a conventional hanging pendulum arm attached to a balance mechanism that converts horizontal deflections produced by the operating thruster into amplified vertical motion of a secondary arm. The level of amplification is changed through adjustment of the location of one of the pivot points linking the system. Response of the system depends on the relative magnitudes of the restoring moments applied by the displaced thruster mass and the twisting torsional pivots connecting the members of the balance mechanism. Displacement is measured using a non-contact, optical linear gap displacement transducer and balance oscillatory motion is attenuated using a passive, eddy-current damper. The thrust stand employs an automated leveling and thermal control system. Pools of liquid gallium are used to deliver power to the thruster without using solid wire connections, which can exert undesirable time-varying forces on the balance. These systems serve to eliminate sources of zero-drift that can occur as the stand thermally or mechanically shifts during the course of an experiment. An in-situ calibration rig allows for steady-state calibration before, during and after thruster operation. Thrust measurements were carried out on a cylindrical Hall thruster that produces mN-level thrust. The measurements were very repeatable, producing results that compare favorably with previously published performance data, but with considerably smaller uncertainty.

78 FR 48657 - Procurement List; Additions

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-09

... Divider, 4 Sections, Light Blue NSN: 7530-00-NIB-1098--Folder, File, Hanging, Light Blue, Letter Size, 2-Dividers, 6 Sections NSN: 7530-00-NIB-1099--Folder, File, Hanging, Light Blue, Legal Size, 1-Divider, 4 Sections NSN: 7530-00-NIB-1100--Folder, File, Hanging, Light Blue, Legal Size, 2-Dividers, 6 Sections NPA...

75 FR 73074 - Duke Energy Hanging Rock II, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-29

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER11-2064-000] Duke Energy Hanging Rock II, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for... proceeding, of Duke Energy Hanging Rock II, LLC's application for market-based rate authority, with an...

The Hanging Cord with a Real Tip Mass

ERIC Educational Resources Information Center

Deschaine, J. S.; Suits, B. H.

2008-01-01

Normal mode solutions for the perfectly flexible hanging cord problem have been known for over 200 years. More recently, theoretical results for a hanging cord with a point mass attached were presented. Here the theoretical results are tested experimentally using high-precision techniques which are accessible for use in an introductory laboratory.…

Hang-It-Up Artists

ERIC Educational Resources Information Center

Szekely, George

2009-01-01

The best lesson ideas often derive from childhood recollections. When brought to class, play memories and art mementos from the teacher's childhood paint a powerful homage to children's art. A survey of a child's room in the dark, or with lights on, discloses interesting hanging sites, means of attachment and unusual items drafted for hanging, all…

Adiabatic dynamics of one-dimensional classical Hamiltonian dissipative systems

NASA Astrophysics Data System (ADS)

Pritula, G. M.; Petrenko, E. V.; Usatenko, O. V.

2018-02-01

A linearized plane pendulum with the slowly varying mass and length of string and the suspension point moving at a slowly varying speed is presented as an example of a simple 1D mechanical system described by the generalized harmonic oscillator equation, which is a basic model in discussion of the adiabatic dynamics and geometric phase. The expression for the pendulum geometric phase is obtained by three different methods. The pendulum is shown to be canonically equivalent to the damped harmonic oscillator. This supports the mathematical conclusion, not widely accepted in physical community, of no difference between the dissipative and Hamiltonian 1D systems.

Computer simulation of multigrid body dynamics and control

NASA Technical Reports Server (NTRS)

Swaminadham, M.; Moon, Young I.; Venkayya, V. B.

1990-01-01

The objective is to set up and analyze benchmark problems on multibody dynamics and to verify the predictions of two multibody computer simulation codes. TREETOPS and DISCOS have been used to run three example problems - one degree-of-freedom spring mass dashpot system, an inverted pendulum system, and a triple pendulum. To study the dynamics and control interaction, an inverted planar pendulum with an external body force and a torsional control spring was modeled as a hinge connected two-rigid body system. TREETOPS and DISCOS affected the time history simulation of this problem. System state space variables and their time derivatives from two simulation codes were compared.

[Sensory illusions in hang-gliding].

PubMed

Bousquet, F; Bizeau, A; Resche-Rigon, P; Taillemite, J P; De Rotalier

1997-01-01

Sensory illusions in hang-gliding and para-gliding. Hang-gliding and para-gliding are at the moment booming sports. Sensory illusions are physiological phenomena sharing the wrong perception of the pilote's real position in space. These phenomena are very familiar to aeroplane pilotes, they can also be noticed on certain conditions with hang-gliding pilotes. There are many and various sensory illusions, but only illusions of vestibular origin will be dealt with in this article. Vestibular physiology is reminded with the working principle of a semicircular canal. Physiology and laws of physics explain several sensory illusions, especially when the pilote loses his visual landmarks: flying through a cloud, coriolis effect. Also some specific stages of hang-gliding foster those phenomena: spiraling downwards, self-rotation, following an asymetric closing of the parachute, spin on oneself. Therefore a previous briefing for the pilotes seems necessary.

Experimental Control of Simple Pendulum Model

ERIC Educational Resources Information Center

Medina, C.

2004-01-01

This paper conveys information about a Physics laboratory experiment for students with some theoretical knowledge about oscillatory motion. Students construct a simple pendulum that behaves as an ideal one, and analyze model assumption incidence on its period. The following aspects are quantitatively analyzed: vanishing friction, small amplitude,…

A passive pendulum wobble damper for a low spin rate Jupiter flyby spacecraft

NASA Technical Reports Server (NTRS)

Fowler, R. C.

1972-01-01

When the spacecraft has a low spin rate and precise pointing requirements, the wobble angle must be damped in a time period equivalent to a very few wobble cycles. The design, analysis, and test of a passive pendulum wobble damper are described.

Frozen Pendulum?

ERIC Educational Resources Information Center

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…

Deterrence and Engagement: A Blended Strategic Approach to a Resurgent Russia

DTIC Science & Technology

2016-04-15

increasing the alliances’ hard power projection to contain and deter further aggression. This strategic approach represents an extreme pendulum ...This strategic approach represents an extreme pendulum swing that is a polar opposite of the U.S. administration’s 2009 approach to ‘Reset’ relations

Rendering the "Not-So-Simple" Pendulum Experimentally Accessible.

ERIC Educational Resources Information Center

Jackson, David P.

1996-01-01

Presents three methods for obtaining experimental data related to acceleration of a simple pendulum. Two of the methods involve angular position measurements and the subsequent calculation of the acceleration while the third method involves a direct measurement of the acceleration. Compares these results with theoretical calculations and…

Tuned mass damping system for a pendulum in gravity and microgravity fields

NASA Astrophysics Data System (ADS)

Atour, Farah

2016-07-01

An electrodynamic tether is a simple idea, but one with an amazing number of uses. Electrodynamic tether is a long conductor wire that is attached to the satellite, which can act as a generator or motor, from its motion through the earth's magnetic field. And it has the potential to make space travel significantly cheaper. The lack of electrodynamic tether's widespread in common applications can be attributed to the variable Lorentz forces occuring on the tethers, which will cause them to oscillate and may go out of control, de-orbit the satellite and fall to Earth. A tuned mass damper system, for short refered as tilger, is suggested as damper of oscillations of tethers. A system composed of a tuned mass damper and a simple pendulum simulating the tether was therefore constructed. 350 sets of experimental trials were done on the system, while it was installed inside a drop tower capsule resting on the ground, in order to pick four optimum setup experiments that will undergo a series of microgravity experiments at the Bremen Drop Tower in Bremen, Germany. The GJU Bachelor Research students found that the oscillations of the simple pendulum will not be affected by the tilger during the free fall experiment, except if a feedback mechanism is installed between the simple pendulum and the tilger. In this case, the tilger will dampen the simple pendulum oscillations during free fall.

Robust Control Algorithm for a Two Cart System and an Inverted Pendulum

NASA Technical Reports Server (NTRS)

Wilson, Chris L.; Capo-Lugo, Pedro

2011-01-01

The Rectilinear Control System can be used to simulate a launch vehicle during liftoff. Several control schemes have been developed that can control different dynamic models of the rectilinear plant. A robust control algorithm was developed that can control a pendulum to maintain an inverted position. A fluid slosh tank will be attached to the pendulum in order to test robustness in the presence of unknown slosh characteristics. The rectilinear plant consists of a DC motor and three carts mounted in series. Each cart s weight can be adjusted with brass masses and the carts can be coupled with springs. The pendulum is mounted on the first cart and an adjustable air damper can be attached to the third cart if desired. Each cart and the pendulum have a quadrature encoder to determine position. Full state feedback was implemented in order to develop the control algorithm along with a state estimator to determine the velocity states of the system. A MATLAB program was used to convert the state space matrices from continuous time to discrete time. This program also used a desired phase margin and damping ratio to determine the feedback gain matrix that would be used in the LabVIEW program. This experiment will allow engineers to gain a better understanding of liquid propellant slosh dynamics, therefore enabling them to develop more robust control algorithms for launch vehicle systems

Reinforcement learning for stabilizing an inverted pendulum naturally leads to intermittent feedback control as in human quiet standing.

PubMed

Michimoto, Kenjiro; Suzuki, Yasuyuki; Kiyono, Ken; Kobayashi, Yasushi; Morasso, Pietro; Nomura, Taishin

2016-08-01

Intermittent feedback control for stabilizing human upright stance is a promising strategy, alternative to the standard time-continuous stiffness control. Here we show that such an intermittent controller can be established naturally through reinforcement learning. To this end, we used a single inverted pendulum model of the upright posture and a very simple reward function that gives a certain amount of punishments when the inverted pendulum falls or changes its position in the state space. We found that the acquired feedback controller exhibits hallmarks of the intermittent feedback control strategy, namely the action of the feedback controller is switched-off intermittently when the state of the pendulum is located near the stable manifold of the unstable saddle-type upright equilibrium of the inverted pendulum with no active control: this action provides an opportunity to exploit transiently converging dynamics toward the unstable upright position with no help of the active feedback control. We then speculate about a possible physiological mechanism of such reinforcement learning, and suggest that it may be related to the neural activity in the pedunculopontine tegmental nucleus (PPN) of the brainstem. This hypothesis is supported by recent evidence indicating that PPN might play critical roles for generation and regulation of postural tonus, reward prediction, as well as postural instability in patients with Parkinson's disease.

Figuring the Acceleration of the Simple Pendulum

NASA Astrophysics Data System (ADS)

Lieberherr, Martin

2011-12-01

The centripetal acceleration has been known since Huygens' (1659) and Newton's (1684) time.1,2 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.3 But sentences like "the acceleration is always directed towards the equilibrium position" beside the picture of a swing on a circular arc can still be found in textbooks, as e.g. in Ref. 4. Vectors have been invented by Grassmann (1844)5 and are conveniently used to describe the acceleration in curved orbits, but acceleration is more often treated as a scalar with or without sign, as the words acceleration/deceleration suggest. The component tangential to the orbit is enough to deduce the period of the simple pendulum, but it is not enough to discuss the forces on the pendulum, as has been pointed out by Santos-Benito and A. Gras-Marti.6 A suitable way to address this problem is a nice figure with a catch for classroom discussions or homework. When I plotted the acceleration vectors of the simple pendulum in their proper positions, pictures as in Fig. 1 appeared on the screen. The endpoints of the acceleration vectors, if properly scaled, seemed to lie on a curve with a familiar shape: a cardioid. Is this true or just an illusion?

A low-cost municipal sewage treatment system with a combination of UASB and the "fourth-generation" downflow hanging sponge reactors.

PubMed

Tandukar, M; Uemura, S; Machdar, I; Ohashi, A; Harada, H

2005-01-01

This paper presents an evaluation of the process performance of a pilot-scale "fourth generation" downflow hanging sponge (DHS) post-treatment system combined with a UASB pretreatment unit treating municipal wastewater. After the successful operation of the second- and third-generation DHS reactors, the fourth-generation DHS reactor was developed to overcome a few shortcomings of its predecessors. This reactor was designed to further enhance the treatment efficiency and simplify the construction process in real scale, especially for the application in developing countries. Configuration of the reactor was modified to enhance the dissolution of air into the wastewater and to avert the possible clogging of the reactor especially during sudden washout from the UASB reactor. The whole system was operated at a total hydraulic retention time (HRT) of 8 h (UASB: 6 h and DHS: 2 h) for a period of over 600 days. The combined system was able to remove 96% of unfiltered BOD with only 9 mg/L remaining in the final effluent. Likewise, F. coli were removed by 3.45 log with the final count of 10(3) to 10(4) MPN/100 ml. Nutrient removal by the system was also satisfactory.

On the MAF solution of the uniformly lengthening pendulum via change of independent variable in the Bessel's equation

NASA Astrophysics Data System (ADS)

Deniz, Coşkun

Common recipe for the Lengthening Pendulum (LP) involves some change of variables to give a relationship with the Bessel's equation. In this work, semiclassical MAF (Modified Airy Function) solution of the LP is being obtained by first transforming the related Bessel's equation into the normal form via the suggested change of independent variable just as one of our recent work regarding the JWKB solution of the LP in (Deniz, 2017). MAF approximation of the first order Bessel Functions (ν = 1) of both type along with their zeros are being obtained analytically with a very good accuracy as a result of the appropriately chosen associated initial values and they are extended to the neighbouring orders (ν = 0 and 2) by the recursion relations. Although common numerical methods given in the literature require adiabatic LP systems where the lengthening rate is small, MAF solution presented here can safely be used for higher lengthening rates and a criterion for its validity is determined via the use of MAF applicability criterion given in the literature. As a result, the semiclassical MAF method which is normally used for the quantum mechanical and optical waveguide systems is applied to the classical LP system successfully just as our previous work regarding the JWKB solution of the LP. Interestingly, we have very accurate results in the entire domain except for x ≈ 0 .

Effects of unilateral molar distalization with a modified pendulum appliance.

PubMed

Schütze, Stefan F; Gedrange, Tomas; Zellmann, Markus R; Harzer, Winfried

2007-05-01

The purpose of this study was to evaluate skeletal and dentoalveolar changes due to unilateral distalization and to determine side effects. Cephalograms and dental casts before and after distal movement of the maxillary molars with pendulum appliances in 15 consecutively treated patients (5 girls and 10 boys, 12.06 +/- 1.32 years), were included in this study. The duration of distalization was 8.46 +/- 2.23 months. Cephalometric analysis showed no remarkable growth between the 2 measurement times. The mean value for distalization of the first molars was 3.83 +/- 1.09 mm, with distal tipping of 6.45 degrees . The maxillary second molars were also moved distally 2.83 +/- 1.32 mm and tipped distally 14.7 degrees . No significant changes in the position of the third molars were measured. The mean reciprocal mesial movement of the premolars was 1.18 +/- 1.31 mm, with distal tipping of 1.94 degrees . The incisors moved 0.84 +/- 0.79 mm mesially, with mesial tipping of 0.02 degrees and extrusion of 1.21 mm. There was also a significant influence on the contralateral anchorage unit. However, unilateral distalization reduced incisor proclination and induced moderate distal movement of the contralateral anchorage unit based on rotation around a virtual axis perpendicular to the Nance button. Effective distal molar movement and less anchorage loss at the front teeth are advantages of unilateral distalization.

Distribution of hanging garden vegetation associations on the Colorado Plateau, USA

Treesearch

James F. Fowler; N. L. Stanton; Ronald L. Hartman

2007-01-01

Hanging gardens are island-like habitats dominated by mesophytic-hydrophytic plant communities, growing on seeps on the xeric canyon walls of the Colorado Plateau in the American West. We measured the abundance of species and physical microhabitat characteristics of 73 individual hanging gardens during the growing seasons of 1991-1993. Cluster analysis of a simplified...

Analysis and experimental studies of the control of hang gliders

NASA Technical Reports Server (NTRS)

Phillips, W. H.

1974-01-01

A theoretical analysis of the longitudinal and lateral characteristics of hang gliders in straight flight, pullups, and turns is presented. Some examples of the characteristics of a straight-wing configuration and a Rogallo-wing configuration are given. A means for improving the control of hang gliders while retaining the same basic control feel is proposed.

Fabrication and Operation of Microfluidic Hanging-Drop Networks.

PubMed

Misun, Patrick M; Birchler, Axel K; Lang, Moritz; Hierlemann, Andreas; Frey, Olivier

2018-01-01

The hanging-drop network (HDN) is a technology platform based on a completely open microfluidic network at the bottom of an inverted, surface-patterned substrate. The platform is predominantly used for the formation, culturing, and interaction of self-assembled spherical microtissues (spheroids) under precisely controlled flow conditions. Here, we describe design, fabrication, and operation of microfluidic hanging-drop networks.

Expedition 54 plaque hanging ceremony

NASA Image and Video Library

2018-04-26

NASA astronauts Joe Acaba and Mark Vande Hei Acaba visited Marshall April 11 for their honorary Expedition 54 plaque hanging ceremony and to provide valuable feedback of their on-orbit science investigations with the Payload Operations and Integration Center team. Chris Buckley is awarded privilege of hanging Mission 54 placque, shown here with Astronaut Mark Vande Hei (L) and Astronaut Joe Acaba

Fact Sheet: FY2017 National Defense Authorization Act (NDAA) DOD Reform Proposals

DTIC Science & Technology

2016-05-25

this critical organizational framework, while still preserving its spirit and intent. For example, we can see in some areas how the pendulum between...or where subsequent world events suggest nudging the pendulum further, as in taking more steps to strengthen the capability of the Chairman and the

49 CFR 572.137 - Test conditions and instrumentation.

Code of Federal Regulations, 2011 CFR

2011-10-01

...—Class 1000 (2) Neck: (i) Forces—Class 1000 (ii) Moments—Class 600 (iii) Pendulum acceleration—Class 180... and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv) Forces—Class 1000 (v...—Class 180 (6) Femur forces and knee pendulum—Class 600 (n) Coordinate signs for instrumentation polarity...

49 CFR 572.137 - Test conditions and instrumentation.

Code of Federal Regulations, 2010 CFR

2010-10-01

...—Class 1000 (2) Neck: (i) Forces—Class 1000 (ii) Moments—Class 600 (iii) Pendulum acceleration—Class 180... and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv) Forces—Class 1000 (v...—Class 180 (6) Femur forces and knee pendulum—Class 600 (n) Coordinate signs for instrumentation polarity...

49 CFR 572.137 - Test conditions and instrumentation.

Code of Federal Regulations, 2013 CFR

2013-10-01

...—Class 1000 (2) Neck: (i) Forces—Class 1000 (ii) Moments—Class 600 (iii) Pendulum acceleration—Class 180... and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv) Forces—Class 1000 (v...—Class 180 (6) Femur forces and knee pendulum—Class 600 (n) Coordinate signs for instrumentation polarity...

49 CFR 572.137 - Test conditions and instrumentation.

Code of Federal Regulations, 2014 CFR

2014-10-01

...—Class 1000 (2) Neck: (i) Forces—Class 1000 (ii) Moments—Class 600 (iii) Pendulum acceleration—Class 180... and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv) Forces—Class 1000 (v...—Class 180 (6) Femur forces and knee pendulum—Class 600 (n) Coordinate signs for instrumentation polarity...

49 CFR 572.137 - Test conditions and instrumentation.

Code of Federal Regulations, 2012 CFR

2012-10-01

...—Class 1000 (2) Neck: (i) Forces—Class 1000 (ii) Moments—Class 600 (iii) Pendulum acceleration—Class 180... and pendulum accelerations—Class 180 (iii) Sternum deflection—Class 600 (iv) Forces—Class 1000 (v...—Class 180 (6) Femur forces and knee pendulum—Class 600 (n) Coordinate signs for instrumentation polarity...

New Approaches to Data Acquisitions in a Torsion Pendulum Experiment

ERIC Educational Resources Information Center

Jiang, Daya; Xiao, Jinghua; Li, Haihong; Dai, Qionglin

2007-01-01

In this paper, two simple non-contact and cost-effective methods to acquire data in the student laboratory are applied to investigate the motion of a torsion pendulum. The first method is based on a Hall sensor, while the second makes use of an optical mouse.

Recurrence Effects in the Parametric Spring Pendulum.

ERIC Educational Resources Information Center

Falk, Lars

1978-01-01

Gives a perturbation analysis to recurrence effects of the spring pendulum. The recurrence depends on two conservation laws which determine the motion in an intermediate region; oscillations outside this region are unstable and must return. Gives the relation to Fermi-Pasta-Ulam problem together with the explicit solution. (Author/GA)

Soup-Can Pendulum

ERIC Educational Resources Information Center

Peters, Randall D.

2004-01-01

In these studies, a vegetable can containing fluid was swung as a pendulum by supporting its end-lips with a pair of knife edges. The motion was measured with a capacitive sensor and the logarithmic decrement in free decay was estimated from computer-collected records. Measurements performed with nine different homogeneous liquids, distributed…

A Rolling Pendulum Bob: Conservation of Energy and Partitioning of Kinetic Energy.

ERIC Educational Resources Information Center

Helrich, Carl; Lehman, Thomas

1979-01-01

Describes a pendulum in which the spherical bob can roll on a track of the same arc as it swings when suspended by a cord. Comparison of the motion in the two mentioned cases shows the effect of rotational kinetic energy when the bob rolls. (GA)

Water resources and effects of potential surface coal mining on dissolved solids in Hanging Woman Creek basin, southeastern Montana

USGS Publications Warehouse

Cannon, M.R.

1989-01-01

Groundwater resources of the Hanging Woman Creek basin, Montana include Holocene and Pleistocene alluvial aquifers and sandstone , coal, and clinker aquifers in the Paleocene Fort Union Formation. Surface water resources are composed of Hanging Woman Creek, its tributaries, and small stock ponds. Dissolved-solids concentrations in groundwater ranged from 200 to 11,00 mg/L. Generally, concentrations were largest in alluvial aquifers and smallest in clinker aquifers. Near its mouth, Hanging Woman Creek had a median concentration of about 1,800 mg/L. Mining of the 20-foot to 35-foot-thick Anderson coal bed and 3-foot to 16-foot thick Dietz coal bed could increase dissolved-solids concentrations in shallow aquifers and in Hanging Woman Creek because of leaching of soluble minerals from mine spoils. Analysis of saturated-paste extracts from 158 overburden samples indicated that water moving through mine spoils would have a median increase in dissolved-solids concentration of about 3,700 mg/L, resulting in an additional dissolved-solids load to Hanging Woman Creek of about 3.0 tons/day. Hanging Woman Creek near Birney could have an annual post-mining dissolved-solids load of 3,415 tons at median discharge, a 47% increase from pre-mining conditions load. Post-mining concentrations of dissolved solids, at median discharge, could range from 2,380 mg/L in March to 3,940 mg/L in August, compared to mean pre-mining concentrations that ranged from 1,700 mg/L in July, November, and December to 2,060 mg/L in May. Post-mining concentrations and loads in Hanging Woman Creek would be smaller if a smaller area were mined. (USGS)

Stripping voltammetry in environmental and food analysis.

PubMed

Brainina, K Z; Malakhova, N A; Stojko, N Y

2000-10-01

The review covers over 230 papers published mostly in the last 5 years. The goal of the review is to attract the attention of researchers and users to stripping voltammetry in particular, its application in environmental monitoring and analysis of foodstuffs. The sensors employed are impregnated graphite, carbon paste, thick film carbon/graphite and thin film metallic electrodes modified in-situ or beforehand. Hanging mercury drop electrodes and mercury coated glassy carbon electrodes are also mentioned. Strip and long-lived sensors for portable instruments and flow through systems are discussed as devices for future development and application of stripping voltammetry.

Test of spatial isotropy using a cryogenic torsion pendulum

NASA Technical Reports Server (NTRS)

Phillips, Peter R.

1987-01-01

Motion of the earth through the cosmic neutrino background, or through certain kinds of vacuum states, produces a term of the form g(sigma) x v in the energy of an electron. To search for such a term, a cryogenic torsion pendulum carrying a transversely polarized magnet was used. Superconducting shields reduced magnetic torques. A sigma x v term would produce a sinusoidal oscillation of the pendulum with a period of one sidereal day. Such an oscillation was not detected, and a new limit of 8.5 x 10 to the -18th eV has been set for the splitting of the spin states of an electron at rest on the earth.

Mini-implant-borne Pendulum B appliance for maxillary molar distalisation: design and clinical procedure.

PubMed

Wilmes, Benedict; Katyal, Vandana; Drescher, Dieter

2014-11-01

A treatment objective of upper molar distalisation may often be required during the correction of a malocclusion. Distalisation is not only indicated for the management of Class II patients, but also for Class III surgery patients who require decompensation in the upper arch if upper incisor retrusion is needed. Unfortunately, most conventional intra-oral devices for non-compliance maxillary molar distalisation experience anchorage loss. A Pendulum type of appliance and a mini-implant-borne distalisation mechanism have been designed which can be inserted at chair-side, without a prior laboratory procedure and immediately after mini-implant placement. For re-activation purposes, a distal screw may be added to the Pendulum B appliance.

Diagrammatic theory of transition of pendulum like systems. [orbit-orbit and spin-orbit gravitational resonance interactions

NASA Technical Reports Server (NTRS)

Yoder, C. F.

1979-01-01

Orbit-orbit and spin-orbit gravitational resonances are analyzed using the model of a rigid pendulum subject to both a time-dependent periodic torque and a constant applied torque. First, a descriptive model of passage through resonance is developed from an examination of the polynomial equation that determines the extremes of the momentum variable. From this study, a probability estimate for capture into libration is derived. Second, a lowest order solution is constructed and compared with the solution obtained from numerical integration. The steps necessary to systematically improve this solution are also discussed. Finally, the effect of a dissipative term in the pendulum equation is analyzed.

Pendulum Exercises After Hip Arthroscopy: A Video Technique.

PubMed

Sauber, Ryan; Saborio, George; Nickel, Beth M; Kivlan, Benjamin R; Christoforetti, John J

2016-08-01

Advanced hip joint-preserving arthroscopic techniques have been shown to improve patient-reported functional outcomes with low rates of postoperative complications. Prior work has shown that formation of adhesive scar is a potential source of persistent pain and cause for revision surgery. As resources for postoperative in-studio physical therapy become scarce, a home-based strategy to avoid scar formation without adding formal therapy cost may be beneficial. The purpose of this technical note is to introduce a patient-centered educational video technique for home-caregiver delivery of manual hip pendulum exercises in the postoperative setting. This video technique offers access to our method for pendulum exercise as part of early recovery after advanced hip arthroscopy.

Combined input shaping and feedback control for double-pendulum systems

NASA Astrophysics Data System (ADS)

Mar, Robert; Goyal, Anurag; Nguyen, Vinh; Yang, Tianle; Singhose, William

2017-02-01

A control system combining input shaping and feedback is developed for double-pendulum systems subjected to external disturbances. The proposed control method achieves fast point-to-point response similar to open-loop input-shaping control. It also minimizes transient deflections during the motion of the system, and disturbance-induced residual swing using the feedback control. Effects of parameter variations such as the mass ratio of the double pendulum, the suspension length ratio, and the move distance were studied via numerical simulation. The most important results were also verified with experiments on a small-scale crane. The controller effectively suppresses the disturbances and is robust to modelling uncertainties and task variations.

A double pendulum swing experiment: In search of a better bat

NASA Astrophysics Data System (ADS)

Cross, Rod

2005-04-01

Experimental results on the large-amplitude motion of a double pendulum are presented, with emphasis on the first half cycle. The initial part of the swing is reproducible and is of interest in modeling various human movement activities such as running, throwing, kicking, and the swing of a bat or racquet. Beyond this time, the motion is chaotic. The forces and torques acting on each pendulum segment are analyzed to explain its motion. The results show how a "perfect" bat could be designed where all the kinetic energy from the player's arms is transferred to the ball and none is retained in the arms or the bat after the impact.

From psyche to soma? Changing accounts of antisocial personality disorders in the American Journal of Psychiatry.

PubMed

Pickersgill, Martyn

2010-09-01

The history of psychiatry is often portrayed through the metaphor of a pendulum, the profession swinging back and forth between a concern with psyche and soma. Recent work critiquing the pendulum metaphor, however, suggests that it does not account for the complexity of psychiatry. This article explores the metaphor through an analysis of the changing aetiological accounts of personality disorders associated with antisocial behaviour advanced in the American Journal of Psychiatry from 1950 onwards. It is argued that the social, scientific and economic factors which help shape overarching professional trends in psychiatry only partly structure personality disorder discourse. If the pendulum swings, therefore, not all psychiatrists move with it.

Surface-tension driven open microfluidic platform for hanging droplet culture

PubMed Central

de Groot, T. E.; Veserat, K. S.; Berthier, E.; Beebe, D. J.; Theberge, A. B.

2015-01-01

The hanging droplet technique for three-dimensional tissue culture has been used for decades in biology labs, with the core technology remaining relatively unchanged. Recently microscale approaches have expanded the capabilities of the hanging droplet method, making it more user-friendly. We present a spontaneously driven, open hanging droplet culture platform to address many limitations of current platforms. Our platform makes use of two interconnected hanging droplet wells, a larger well where cells are cultured and a smaller well for user interface via a pipette. The two-well system results in lower shear stress in the culture well during fluid exchange, enabling shear sensitive or non-adherent cells to be cultured in a droplet. The ability to perform fluid exchanges in-droplet enables long-term culture, treatment, and characterization without disruption of the culture. The open well format of the platform was utilized to perform time-dependent coculture, enabling culture configurations with bone tissue scaffolds and cells grown in suspension. The open nature of the system allowed the direct addition or removal of tissue over the course of an experiment, manipulations that would be impractical in other microfluidic or hanging droplet culture platforms. PMID:26660268

Classroom Explorations: Pendulums, Mirrors, and Galileo's Drama

ERIC Educational Resources Information Center

Cavicchi, Elizabeth

2011-01-01

What do you see in a mirror when not looking at yourself? What goes on as a pendulum swings? Undergraduates in a science class supposed that these behaviors were obvious until their explorations exposed questions with no quick answers. While exploring materials, students researched Galileo, his trial, and its aftermath. Galileo came to life both…

Swedish Defence Acquisition Transformation: A Research Agenda

DTIC Science & Technology

2015-05-13

presentation • A small country perspective • The swinging pendulum : “From preparedness to deployment to preparedness?” – or “from national defence to PSOs to...history of war The swinging (political) pendulum • A. 200 years of peace – Standing in preparedness • B. Post Cold War – Deployed on PSOs • C

Figuring the Acceleration of the Simple Pendulum

ERIC Educational Resources Information Center

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…

Pendulum Motion and Differential Equations

ERIC Educational Resources Information Center

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…

An Experiment on a Physical Pendulum and Steiner's Theorem

ERIC Educational Resources Information Center

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…

Reconsidering Simulations in Science Education at a Distance: Features of Effective Use

ERIC Educational Resources Information Center

Blake, C.; Scanlon, E.

2007-01-01

This paper proposes a reconsideration of use of computer simulations in science education. We discuss three studies of the use of science simulations for undergraduate distance learning students. The first one, "The Driven Pendulum" simulation is a computer-based experiment on the behaviour of a pendulum. The second simulation, "Evolve" is…

Dynamics and Thermodynamics of Many Particle Cold Atom Systems

DTIC Science & Technology

2016-05-05

Dynamical Stability of a Many-body Kapitza Pendulum , R. Citro, E. G. Dalla Torre, L. DÁlessio, A. Polkovnikov, M. Babadi, T. Oka, E. Demler, Annals...Kapitza Pendulum , R. Citro, E. G. Dalla Torre, L. DÁlessio, A. Polkovnikov, M. Babadi, T. Oka, E. Demler, Annals of Physics 360, 694-710 (2015). 17

Periodic solutions of a spring-pendulum system.

NASA Technical Reports Server (NTRS)

Broucke, R.; Baxa, P. A.

1973-01-01

A study has been made of a dynamical system composed of a pendulum and a harmonic oscillator, in order to show the remarkable resemblance with many classical celestial mechanics problems, in particular, the restricted three-body problem. It is shown that the well-known investigations of periodic orbits can be applied to the present dynamics problem.

METHODOLOGICAL NOTES: Rotation of the swing plane of Foucault's pendulum and Thomas spin precession: two sides of one coin

NASA Astrophysics Data System (ADS)

Krivoruchenko, Mikhail I.

2009-08-01

Using elementary geometric tools, we apply essentially the same methods to derive expressions for the rotation angle of the swing plane of Foucault's pendulum and the rotation angle of the spin of a relativistic particle moving in a circular orbit (the Thomas precession effect).

Pendulum Testing of an FRP Composite Guardrail: FOIL Test Numbers 96POl9 Through 96PO23, 97POO1, and 97POO2

DOT National Transportation Integrated Search

1998-03-01

This report contains the test setup and results from seven pendulum crash : tests conducted at the Federal Outdoor Impact Laboratory (FOIL) located at the Turner-Fairbank Highway Research Center (TFHRC) in McLean, Virginia. The tests were conducted o...

Getting into the Swing of Things: Using Pendulums to Learn the Scientific Method.

ERIC Educational Resources Information Center

Grambo, Gregory

1996-01-01

A middle school science teacher describes the learning and thinking processes of his class as they worked and played with pendulums and learned to build a swing that could tell time. The article illustrates how students can learn the value of the scientific method for problem solving. (DB)

Measurement method of magnetic field for the wire suspended micro-pendulum accelerometer.

PubMed

Lu, Yongle; Li, Leilei; Hu, Ning; Pan, Yingjun; Ren, Chunhua

2015-04-13

Force producer is one of the core components of a Wire Suspended Micro-Pendulum Accelerometer; and the stability of permanent magnet in the force producer determines the consistency of the acceleration sensor's scale factor. For an assembled accelerometer; direct measurement of magnetic field strength is not a feasible option; as the magnetometer probe cannot be laid inside the micro-space of the sensor. This paper proposed an indirect measurement method of the remnant magnetization of Micro-Pendulum Accelerometer. The measurement is based on the working principle of the accelerometer; using the current output at several different scenarios to resolve the remnant magnetization of the permanent magnet. Iterative Least Squares algorithm was used for the adjustment of the data due to nonlinearity of this problem. The calculated remnant magnetization was 1.035 T. Compared to the true value; the error was less than 0.001 T. The proposed method provides an effective theoretical guidance for measuring the magnetic field of the Wire Suspended Micro-Pendulum Accelerometer; correcting the scale factor and temperature influence coefficients; etc.

Trypsin inhibitors from Capsicum baccatum var. pendulum leaves involved in Pepper yellow mosaic virus resistance.

PubMed

Moulin, M M; Rodrigues, R; Ribeiro, S F F; Gonçalves, L S A; Bento, C S; Sudré, C P; Vasconcelos, I M; Gomes, V M

2014-11-07

Several plant organs contain proteinase inhibitors, which are produced during normal plant development or are induced upon pathogen attack to suppress the enzymatic activity of phytopathogenic microorganisms. In this study, we examined the presence of proteinase inhibitors, specifically trypsin inhibitors, in the leaf extract of Capsicum baccatum var. pendulum inoculated with PepYMV (Pepper yellow mosaic virus). Leaf extract from plants with the accession number UENF 1624, which is resistant to PepYMV, was collected at 7 different times (0, 24, 48, 72, 96, 120, and 144 h). Seedlings inoculated with PepYMV and control seedlings were grown in a growth chamber. Protein extract from leaf samples was partially purified by reversed-phase chromatography using a C2/C18 column. Residual trypsin activity was assayed to detect inhibitors followed by Tricine-SDS-PAGE analysis to determine the N-terminal peptide sequence. Based on trypsin inhibitor assays, trypsin inhibitors are likely constitutively synthesized in C. baccatum var. pendulum leaf tissue. These inhibitors are likely a defense mechanism for the C. baccatum var. pendulum- PepYMV pathosystem.

Changes consequent to maxillary molar distalization with the bone-anchored pendulum appliance

PubMed Central

Cambiano, Aldo Otazú; Janson, Guilherme; Fuziy, Acácio; Garib, Daniela Gamba; Lorenzoni, Diego Coelho

2017-01-01

OBJECTIVES: This retrospective study aimed to evaluate the dentoalveolar, skeletal, and soft tissue effects obtained with bone-anchored pendulum appliance in patients with Class II malocclusion. MATERIALS AND METHODS: A total of 18 patients (4 male, 14 female) at a mean pretreatment age of 14.0 years (+1.08) were enrolled in this study. All patients were treated with the bone-anchored pendulum appliance for an average duration of 4.8 months. Only the active distalization period was evaluated with predistalization and postdistalization lateral cephalograms. Skeletal, dentoalveolar, and soft tissue variables were obtained. Based on these variables, the treatment effects were evaluated with dependent t-test. RESULTS: Correction of Class II molar relationship resulted from distal movement of 3.45 mm and tipping of 11.24° of the first maxillary molars. The premolars were distalized accompanying the molars. CONCLUSIONS: The bone-anchored pendulum appliance proved to be an effective method for distalization of maxillary molars in cases that require maximum anchorage, avoiding reciprocal mesial movement of premolars and incisors. PMID:29119095

Distalization of Maxillary First Permanent Molar by Pendulum Appliance in Mixed Dentition Period.

PubMed

Paranna, Sujatha; Shetty, Prakashchandra; Anandakrishna, Latha; Rawat, Anuradha

2017-01-01

Mesial drifting of molar teeth in maxillary arch is corrected by movement of the molars distally. In addition to traditional distal movement techniques, such as extraoral force application and removable appliances, various intra-arch devices have been introduced since 1980s. These intra-arch appliances have nearly eliminated the need for patient cooperation. The purpose of this paper is to report a case of 10-year-old male patient with loss of space in maxillary molar teeth treated by intra-arch appliance-pendulum appliance by distalization of maxillary first permanent molar teeth. Distaliza-tion of the permanent molar teeth helped in proper eruption of second premolar teeth without any extensive treatment procedures. In the present case report, the treatment of developing malocclusion was corrected by utilizing the concept of interceptive orthodontics. Hence, correction of space loss in mixed dentition period using pendulum appliance can eliminate the fixed orthodontic therapy. Paranna S, Shetty P, Anandakrishna L, Rawat A. Distalization of Maxillary First Permanent Molar by Pendulum Appliance in Mixed Dentition Period. Int J Clin Pediatr Dent 2017;10(3):299-301.

Balancing a simulated inverted pendulum through motor imagery: an EEG-based real-time control paradigm.

PubMed

Yue, Jingwei; Zhou, Zongtan; Jiang, Jun; Liu, Yadong; Hu, Dewen

2012-08-30

Most brain-computer interfaces (BCIs) are non-time-restraint systems. However, the method used to design a real-time BCI paradigm for controlling unstable devices is still a challenging problem. This paper presents a real-time feedback BCI paradigm for controlling an inverted pendulum on a cart (IPC). In this paradigm, sensorimotor rhythms (SMRs) were recorded using 15 active electrodes placed on the surface of the subject's scalp. Subsequently, common spatial pattern (CSP) was used as the basic filter to extract spatial patterns. Finally, linear discriminant analysis (LDA) was used to translate the patterns into control commands that could stabilize the simulated inverted pendulum. Offline trainings were employed to teach the subjects to execute corresponding mental tasks, such as left/right hand motor imagery. Five subjects could successfully balance the online inverted pendulum for more than 35s. The results demonstrated that BCIs are able to control nonlinear unstable devices. Furthermore, the demonstration and extension of real-time continuous control might be useful for the real-life application and generalization of BCI. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Mechanical design of the University of Florida Torsion Pendulum for testing the LISA Gravitational Reference Sensor

NASA Astrophysics Data System (ADS)

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.

Reinforcement learning state estimator.

PubMed

Morimoto, Jun; Doya, Kenji

2007-03-01

In this study, we propose a novel use of reinforcement learning for estimating hidden variables and parameters of nonlinear dynamical systems. A critical issue in hidden-state estimation is that we cannot directly observe estimation errors. However, by defining errors of observable variables as a delayed penalty, we can apply a reinforcement learning frame-work to state estimation problems. Specifically, we derive a method to construct a nonlinear state estimator by finding an appropriate feedback input gain using the policy gradient method. We tested the proposed method on single pendulum dynamics and show that the joint angle variable could be successfully estimated by observing only the angular velocity, and vice versa. In addition, we show that we could acquire a state estimator for the pendulum swing-up task in which a swing-up controller is also acquired by reinforcement learning simultaneously. Furthermore, we demonstrate that it is possible to estimate the dynamics of the pendulum itself while the hidden variables are estimated in the pendulum swing-up task. Application of the proposed method to a two-linked biped model is also presented.

Estimating and Comparing Dam Deformation Using Classical and GNSS Techniques

PubMed Central

Barzaghi, Riccardo; De Gaetani, Carlo Iapige

2018-01-01

Global Navigation Satellite Systems (GNSS) receivers are nowadays commonly used in monitoring applications, e.g., in estimating crustal and infrastructure displacements. This is basically due to the recent improvements in GNSS instruments and methodologies that allow high-precision positioning, 24 h availability and semiautomatic data processing. In this paper, GNSS-estimated displacements on a dam structure have been analyzed and compared with pendulum data. This study has been carried out for the Eleonora D’Arborea (Cantoniera) dam, which is in Sardinia. Time series of pendulum and GNSS over a time span of 2.5 years have been aligned so as to be comparable. Analytical models fitting these time series have been estimated and compared. Those models were able to properly fit pendulum data and GNSS data, with standard deviation of residuals smaller than one millimeter. These encouraging results led to the conclusion that GNSS technique can be profitably applied to dam monitoring allowing a denser description, both in space and time, of the dam displacements than the one based on pendulum observations. PMID:29498650