Motion Of Pendulum Research Articles

Analysis of Influence of Stratospheric Airship’s Key Parameter Perturbation on Motion Mode

The stratospheric airship is taken as the research object, and the motion mode analysis of the stratospheric airship is carried out. The influence of key parameters such as the center of mass, the center of buoyance, and the aerodynamic stability moment on the motion mode of stratospheric airship are analyzed and summarized in detail. According to the simulation and analysis results, unlike high-speed and high-dynamic aircrafts such as airplanes, the motion modes of the stratospheric airship are hardly affected by the perturbation of aerodynamic stability moment; the perturbations of the vertical center of mass and the vertical center of buoyancy have a great influence on the pitch pendulum motion modes, and their parameter perturbations affect the frequency of the pitch pendulum motion and also the stability of the pitch pendulum motion; the axial mass center location perturbation not only changes the damping of pitch pendulum motion but also affects the frequency of the yaw motion attitude motion mode to a certain extent.

The Pulfrich solidity illusion: a surprising demonstration of the visual system's tolerance of solidity violations.

Physical objects behave following the principle of solidity: One solid object cannot pass through another. To what extent does the visual system integrate this physical regularity as a prior constraint? A new variant of the Pulfrich effect demonstrates a surprising degree of tolerance for violations of solidity when pitted against motion and depth cues. When adult participants view a pendulum swinging in the fronto-parallel plane with both eyes (one of which was covered by a light-attenuating filter), they falsely perceive the pendulum as swinging in an elliptical path (known as the "Pulfrich effect"). Here, we show that even when the pendulum's motion takes place entirely behind a solid horizontal bar, observers nevertheless see the pendulum pass through the bar while moving in an ellipse. This illusion suggests that the Pulfrich effect and the underlying stereoscopic depth cues can be robust to object solidity.

Mechanical properties and osteointegration of the mesh structure of a lumbar fusion cage made by 3D printing

The currently popular 3D printing makes it possible to produce spatial scaffolds, the main purpose of which is to obtain implants that have favourable mechanical properties to promote cell adhesion. This study aims to prove the influence of changes in selected geometrical parameters of scaffolds, used in intervertebral cages, on the mechanical properties obtained and thus on the osteointegration of the studied constructs with osteoblasts and fibroblasts. The stiffness values and maximum failure force of four modifications to geometric dimensions of the meshes were determined from the intendation test. Adhesion assays were conducted (including gentle pendulum motion) for Balb/3T3 fibroblasts and NHOst osteoblasts. The study revealed that an important geometrical parameter affecting the strength of the mesh is the height (h) of the connection point between arms of successive mesh cells. There was no significant effect of the mesh geometry on the abundance and survival of Balb/3T3 and NHOst cells. At the same time, fibroblasts were more likely to form colonies in the area where there is fusion of mesh cells, as opposed to osteoblasts that were more numerous at vertices of the mesh.

Initial release condition dependent decoupling motion of a Wilberforce pendulum in the case of near resonance

The vertical and angular oscillation of a Wilberforce pendulum was found to be coupled in the case of resonance. Many studies have discussed the effects of the physical properties of a Wilberforce pendulum on coupled motion. In this article, we mainly study the influence of initial release conditions on the coupled motion of a Wilberforce pendulum in the near resonance case. The experimental results clearly exhibit that the coupled motion phenomenon depends on the initial release condition. Theoretical calculation further demonstrates that the coupled strength between two normal modes is determined by the ratio of initial angular to vertical displacement in the case of near resonance. The experimental results also verify the calculated variation of decoupling coefficient with this displacement ratio. Our study indicates that even in the case of resonance, the motion of a Wilberforce pendulum is probably decoupled at a given initial release condition. Complete decoupled motion is found to appear only when the damping coefficients in vertical and angular motion generate equal energy dissipation rates. The corresponding decoupling phenomenon in the case of resonance, occurs when the initial release energy of vertical and angular motion is equal.

Prevention of Wildfires Using an AI-Based Open Conductor Fault Detection Method on Overhead Line

Overhead lines that are exposed to the outdoors are susceptible to faults such as open conductors on weak points and disconnection caused by external factors such as typhoons. Arcs that occur during disconnection generate energy at a high heat of over 10,000 °C, requiring swift fault shut-off. However, most conventional fault detection methods to protect electrical power systems detect an overcurrent; thus, they can only detect faults after the line is disconnected and the cross-section of the line that generates the arc discharge makes contact with another line or the ground, causing a high risk of fire. Furthermore, in the case of ground faults owing to the disconnection of overhead lines, the load and the grounding impedance are not parallel. Therefore, in the case of the fault current not exceeding the threshold or a high impedance fault due to the high grounding impedance of the surrounding environment, such as grass or trees, it is difficult to determine overhead line faults with conventional fault detection methods. To solve these issues, this paper proposes an AI-based open conductor fault detection method on overhead lines that can clear the fault before the falling open conductor line comes into contact with the ground’s surface so as to prevent fire. The falling time according to the height and span of the overhead line was calculated using a falling conductor model for the overhead line, to which the pendulum motion was applied. The optimal input data cycle that enables fault detection before a line–ground fault occurs was derived. For artificial intelligence learning to prevent wildfires, the voltage and current signals were collected through a total of 432 fault simulations and were wavelet-transformed with a deep neural network to verify the method. The proposed total scheme was simulated and verified with MATLAB.

A simple model of human walking

Aim. We investigate Alexander’s inverted pendulum model, the simplest mathematical model of human walking. Although it successfully explains some kinematic features of human walking, such as the velocity of the body's centre of mass, it does not account for others, like the vertical reaction force and the maximum walking speed. This paper aims to minimally extend Alexander’s model in such a way as to make it a viable and quantitative model of human walking for clinical biomechanics.Material and methods. In order to compare the predictions of Alexander’s model with experimental data on walking, we incorporate in it a robust phenomenological relation between stride frequency and stride length derived in the literature, and we introduce a step-angle dependent muscle force along the pendulum. We then analytically solve the pendulum's motion equation and find the corresponding analytical expression for the average walking speed.Results. The values of the average walking speed for different heights predicted by our model are in excellent agreement with the ones obtained in treadmill experiments. Moreover, it successfully predicts the observed walking-running transition speed, which occurs when the stride length equals the height of an individual. Finally, our extended model satisfactorily reproduces the experimentally observed ground reaction forces in the midstance and terminal stance phases. Consequently, the predicted value of the (height-dependent) maximum walking speed is in reasonable agreement with the one obtained in more sophisticated models of human walking.Conclusions. Augmented with our minimal extensions, Alexander’s model becomes an effective and realistic model of human walking applicable in clinical investigations of the human gate.

Dynamic modeling and analysis of compound pendulum motion of projectile

The influence of air lift on the stability of inaccurate precision strike ammunition is studied, and the mechanical analysis of projectile and its flight stage is carried out. The dynamic equation of projectile under the action of air lift is established and simulated. The angular velocity and angular time-history curve of the compound pendulum motion of the projectile are obtained, and the correctness of the mechanical analysis of compound pendulum motion during flight is verified.

The effects of dihedral angle on hover rigidity and planar maneuvers in rotary-wing UAVs

PurposeAny consensus about the effects of dihedral angle on hover rigidity of rotary-wing unmanned aerial vehicles (RW-UAVs) does not exist in the literature. There are researchers who state that the dihedral angle has an effect on flight stability and researchers who claim the opposite. The discord stems from the different approaches of these groups to the concept of “stability,” the fact that they conduct experiments whose measurements are largely influenced by environmental conditions, and the physical assumptions are not similar. On the other hand, there is no study examining the effect of dihedral angle on the maneuverability of drones either. This study aims to analytically reveal the consequences of dihedral angles in RW-UAVs in terms of flight agility and maneuverability.Design/methodology/approachDihedral angle examinations on both hover rigidity and maneuverability are carried out analytically. Equations of motions for a multicopter’s rigid body with a dihedral angle under two different conditions (zero and nonzero dihedral angles) are derived. Numerical simulations are conducted by defining the simulation parameters, and then displacement graphics for the center of mass are interpreted.FindingsThe presence of a dihedral angle makes the multicopter platforms behave like a pendulum, and this pendulum motion affects the disturbance rejection and the planar maneuver capabilities of multicopters. Since deflections can be spread to the orthonormal axes thanks to rotation about a pivot, net deflections of the geometric center may be diminished. Besides, pendulum motion eases the maneuvers with yaw rotations since the required rotation might occur without rotors’ revolution per minute changes.Practical implicationsProposed dihedral angle implementation may enhance the hover stiffness and maneuverability capabilities of multicopters which, in turn, raise the performance of the drones.Originality/valueThis paper presents the analytical basis for the dihedral angle's effects on flight stability and agility.

Experimental Analysis of the Influence of Gear Design and Catch Weight on the Fluid–Structure Interaction of a Flexible Codend Structure Used in Trawl Fisheries

This study evaluated the behavior of different codend designs to provide the basic information that is relevant for improving the gear selectivity, energy efficiency, to better understand the fish behavior inside the codend, and prevent the probability of the fish escaping. Three different codends were designed from the standard codend commonly used in the Antarctic krill fisheries based on modified Tauti’s law and evaluated. The first and the third codends were designed with four-panel and two-panel nettings, respectively, both made of diamond meshes. While, the second one was a four-panel diamond mesh design with cutting ratio 4:1(N [NBNBN]16). We measured the drag force, codend shape, fluttering codend motions, and the flow field inside and behind the different codends composed of different catch weights under various flow velocities in flume tank. The power spectra density was undertaken to analyze the time evolution of measured parameters. The results showed that the drag force and the codend motion increased and decreased, respectively, with the number of net panels and the cutting ratio. Due to the catch weight and flow velocity, which caused significant codend motions and deformation, a complex interaction occurred between the fluid and the structure, and there was a strong correlation between the codend drag, the codend motions, and the turbulent flow inside and behind the codend. The study showed that the use of the four-panel codend with cutting ratio and the two-panel codend resulted in drag reductions of 6.07% and 6.41%, respectively, compared to the standard codend. The velocity reduction and turbulent kinetic energy were lower inside and behind the four-panel codend than inside and behind the two-panel codend, indicating that turbulent flow through the two-panel codend is more important than through the four-panel codend. The results of the power spectral density analysis showed that the drag and codend motions were mainly low frequency in all codends, with another component related to turbulent flow street. In addition, the two-panel codend showed more unstable behavior with more pendulum motion compared to the four-panel codends, resulting in a smaller mesh size in this codend that could affect swimming energy and thus influence fish escape, making it the least selective codend. The results of this study provide fundamental insights useful for understanding and improving the hydrodynamic performance and selectivity of trawls in the Antarctic krill fishery, especially to reveal the masking effects of the number of net panels on codend design.

Between authority and argumentation: facilitators’ use of power in collaborative governance

Facilitators of collaborative governance structure communication between stakeholders. They influence the process and, in some instances, also the outcome of collaborative governance. Even so, facilitators are, in the literature and in practice, most often reduced to being neutral or seen merely as power sharers. This reductive understanding obscures facilititators’ use of power. The purpose of this paper is to outline a nuanced understanding of authority in facilitation practice. We analyse a Swedish collaborative governance process where a governmental agency facilitates collaboration between actors with conflicting interests. We combine the work of Hannah Arendt and Mark Warren to study authority as relationally performed. We find that facilitators’ use of power takes the form of a pendulum movement between authority and argumentation. Hence, authority and argumentation are linked, rather than incompatible, in facilitation practice. This paper sheds new light on the unrecognised, and yet influential, leadership role that facilitators play.

Estimation of Handheld Ground-Penetrating Radar Antenna Position with Pendulum-Model-Based Extended Kalman Filter

Landmines and explosive remnants of war are a significant threat in tens of countries and other territories, causing the deaths or injuries of thousands of people every year, even long after military conflicts. Effective technical means of remote detecting, localizing, imaging, and identifying mines and other buried explosives are still sought and have a great potential utility. This paper considers a positioning system used as a supporting tool for a handheld ground penetrating radar. Accurate knowledge of the radar antenna position during terrain scanning is necessary to properly localize and visualize the shape of buried objects, which helps in their remote classification and makes demining safer. The positioning system proposed in this paper uses ultrawideband radios to measure the distances between stationary beacons and mobile units. The measurements are processed with an extended Kalman filter based on an innovative dynamics model, derived from the model of a pendulum motion. The results of simulations included in the paper prove that using the proposed pendulum dynamics model ensures a better accuracy than the accuracy obtainable with other typically used dynamics models. It is also demonstrated that our positioning system can estimate the radar antenna position with the accuracy of single centimeters which is required for appropriate imaging of buried objects with the ground penetrating radars.

Simulation of Chaotic Operation οf A Damped Driven Pendulum Using Python

In this paper, we are presenting a new pedagogical method for the introduction of the study of nonlinear systems. Our approach is based on the use of open-source software which is publicly available. In response to this motivation, we are using the Python programming language which offers a holistic approach to scientific research. We will present the analysis of the pendulum motion under the influence of an external force. The differential equation governing the system will be presented and solved using numerical methods. Moreover, the phase diagram of the system will be presented for various system parameters. We will describe the transition to a chaotic operation and the key factors of this procedure. The chaotic behaviour is verified by calculating the maximum Lyapunov exponent. This pedagogical approach emerging is based on the physical properties of the system and not on the numerical methods used so that the student can understand the dynamics of the system more comprehensively.

Evolution of the Land-Sea Silk Road Watershed: Causes and Impacts

From a macro point of view, the evolution of the land Silk Road presents the characteristics of "pendulum movement", while that of the sea Silk Road presents the status of "right-sided normal distribution". Based on some historical facts, it can be determined that the watershed of the land and sea Silk Road was in the Northern Song Dynasty. The main reasons for the watershed of the evolution of the land-Sea Silk Road are as follows: the Northern Song Dynasty failed to control the Northwest Silk Road (East Asia section) effectively, but paid more attention to maritime trade; The development of shipbuilding technology and navigation technology in Northern Song Dynasty and other countries; The economic scale of the Northern Song was much larger than that of the regimes along the Northwest Silk Road. The natural environment in northwest China deteriorated. The watershed of land-sea Silk Road evolution mainly includes: helping shift China's economic center of gravity from the northwest and Central Plains to the southeast, strengthening its control over the southeast and many islands; Strengthen the development of the southeast which has not been fully developed before, and increase the proportion of the population of the southeast in the total population of our country; Strengthen the contact with many overseas countries, trade volume and communication frequency are significantly increased; We will accelerate scientific and cultural exchanges between China and other countries. Many enlightenments can be found by analyzing the emergence of this watershed.

Application of ultrasonic sensor and Arduino in analysing motion of damped pendulum

An easy-to-setup experiment designed to measure the period and air drag coefficients of a damped pendulum is reported. The setup is made up of a solid metal ball and cylindrical shells of various sizes to create air drag. An ultrasonic position sensor (HC-SR04) and an Arduino Uno board were located beneath the pendulum’s lowest position. The pendulum was released from a fixed height at a small initial angle. The periods of the oscillations involving different cylindrical shells were obtained from the time series plots of the pendulum’s position when the pendulum moves back and forth above the sensor. The drag coefficients were measured from five different values of string length. The coefficient was proportional to the size of the cylindrical shells and in agreement with the drag equation for a small Reynolds number.

Study of optimal damping coefficients for devices based on a single-objective optimization model—Considering two types of damping coefficients

Wave energy is an important marine renewable energy source, and one of the key issues in its utilization is to improve the energy conversion of wave energy devices efficiency. In this paper, we consider the pendulum motion of the float in the wave, firstly, we establish the coordinate system for the float system and analyze the forces on the float and the oscillator, establish the initial value system model of the second-order coupled ordinary differential equation system about the displacement function of the float and the oscillator, and then calculate the displacement and velocity of the float and the oscillator under the constant damping coefficient by reducing the order and finite difference. Finally, a single-objective optimization model with the output power of the PTO system as the objective function is established, and the damping coefficients in the cases of constant damping coefficient and variable damping coefficient are found out respectively, so as to maximize the power.

Vinci Power Nap® Synchronization Technology - Neuroarchitecture for better sleep, adding Energy for Life, Reducing Stress and Jet Lag, Improving Wellbeing and Body-Mind Regeneration. Helpful for Leaders, Doctors, Soldiers, Children, Drivers, Pilots, Astronauts, People Traveling On Earth And Beyond

The Vinci Power Nap® neurotechnological system created for energy naps, which can benefits mankind on Earth and in space travels. This cutting edge tool helping to reduce stress, jet lag, regulating the circadian rhythm, improving focus, efficiency, reaction times, preventing losing bone mass, the quality of sleep, health and human wellbeing in future smart cities and Lunar, Martian habitats. The remarkable results can be found in studies on UN Delegates at COP24, UNICEF project for war traumatized refugees women and children, soldiers with PTSD, pilots and analog astronauts, showing the healing power of touching, frequency of rocking, napping in a zero gravity position. Good sleep is needed to reset, recover, strengthen the immune system, also avoid errors resulting from fatigue and jet lag, which is especially important for business leaders, doctors, drivers, athletes, students, soldiers, pilots, astronauts and tourists. The frequency of the VPN technology pendulum movement is a revolution in the synchronization of breathing, heartbeat, delta waves in the brain, during which the best regeneration of the body and mind occurs. Moreover, the pulsating pressure on the skin increase the level of hormones: dopamine, oxytocin, serotonin, etc. All this contributes to the regeneration of sleep and energy, improving human’s psychophysical condition, longevity and advances in sleep and space medicine.

Motion analysis of magnetic spring pendulum

In order to analyze the motion characteristics of the spring pendulum under the action of magnetic field force, the motion of the spring pendulum will be studied by applying a uniform magnetic field in the vertical direction. Firstly, a first-order approximate solution is given by studying the micro-vibration around its equilibrium point. And an approximate solution similar to the Foucault pendulum is also presented in the case of a soft spring with strong ductility. Then, according to the resonance conditions of mechanical vibration, the internal resonance phenomenon of magnetic spring pendulum is discovered, and then the conclusion that the energy of the system is cyclically transmitted between the three modes of breathing, oscillating and deflection is presented subsequently. Finally, the influence of magnetic field strength on the motion stability of the spring pendulum is explored, and not only the bifurcation phenomenon at its equilibrium point is found, but also the complex dynamic behavior including chaotic motion occurs.

Pendulum or Progress? Tax Consultants in the Crisis of Legitimacy

After a series of scandals, the focus is now shifting to tax professionals who have received little attention so far. The paper examines how tax professionals justify their professional activities in the legitimacy crisis of tax planning. Professions have a systemic role and combine commercial interest with social benefit. In the crisis, professionals need to re-legitimize themselves by addressing core societal values in order to secure the benefits associated with professional status. Building on problem-centered qualitative interviews with 45 tax professionals from Germany, Liechtenstein, and Austria with different business models, I show that these tax professionals justify their activities in the crisis via three ideal-typical norms: selective liberal values and counterattacks, elitist shaping, and the benefits for the business location. Most professionals hope for a pendulum movement as a rollback of regulation.

Torsion pendulum measurement method for time varying moment of inertia

A time-varying moment of inertia (MOI) measurement model based on the torsion pendulum method is studied. According to the principle of dynamics, the motion equation of torsion pendulum with single degree of freedom is established by using the second Lagrange equation modeling, which indicates the time-varying MOI can be obtained by the instantaneous undamped natural frequency of torsional pendulum motion and the torsion bar coefficient. Among them, the instantaneous frequency is calculated by the instantaneous angular frequency and envelope signal of angular displacement using Hilbert transform. The torsion bar coefficient is calibrated by the standard weight with known MOI, and has been compensated by temperature. Based on air floating turntable, the torsion pendulum system is built to measure the MOI of fine sand in the funnel, which can minimize the effects of mechanical friction. The relative error of MOI between calculating the result and measuring the value is less than 0.65%, which verifies the effectiveness of the proposed time varying temperature compensation method.

Mechanical parametric feedback-cooling for pendulum-based gravity experiments

Gravitational forces that oscillate at audio-band frequencies are measured with masses suspended as pendulums that have resonance frequencies even lower. If the pendulum is excited by thermal energy or by seismic motion of the environment, the measurement sensitivity is reduced. Conventionally, this problem is mitigated by seismic isolation, potentially combined with cryogenic cooling. Here, we propose mechanical parametric cooling of the pendulum motion, continuously even during the measurements. Different from linear damping, the actuator of our approach does not need a mechanically stable reference point. We report a proof of principle demonstration in the seismic noise dominated regime and achieve a damping factor of the pendulum motion of 5.7. We find a model system for which mechanical parametric feedback cooling reaches the quantum mechanical regime near the ground state. Gravitational-wave detectors would already be improved with much lower cooling factors.