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1
Xie, Shao Rong, Jin Song Miao, Heng Yu Li, Yu Mei Zhou e Jun Luo. "A Control System of Binocular Eyes Based on DSP TMS320F2812". Applied Mechanics and Materials 128-129 (ottobre 2011): 765–70. http://dx.doi.org/10.4028/www.scientific.net/amm.128-129.765.
Testo completoAbstract (sommario):
This paper mainly introduces a binocular eyes system which is similar to the human eyes. The whole control system is based on neural network control model of human eyes, while the structure adopts spherical parallel mechanism to mimic the human eye movement. The whole Binocular control system consists of DSP embedded control system and PC platforms, which achieves the movement of the vestibular ocular reflex, convergence and conjugate movement, thus realizing good tracking of moving targets. This control system has compacted configuration and high reliability. A large number of experiments were done to validate the whole excellent system performance.
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Zhao, Ji Zeng, Min Xu e Wei Fu. "Space Arc Trajectory Planning Based on PCI Motion Control System". Advanced Materials Research 542-543 (giugno 2012): 573–77. http://dx.doi.org/10.4028/www.scientific.net/amr.542-543.573.
Testo completoAbstract (sommario):
This paper presents a method using the PCI motion controller which provides function of space linear interpolation to implement space arc trajectory planning on three dimensional motion platform. While make plane constraint to space spherical, we get space arc trajectory in Cartesian Coordinate System. Using the constraint arc by appropriate of precision discrete, function of space linear interpolation and the movement buffer nested in controller card to implement space arc movement. Writing control interface by using VC++ and actually validated on XYZ-three dimensional motion platform. The result confirmed feasibility and accuracy of this method.
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Wang, J., J. J. Xu e L. Zhang. "Simulation on the aggregation process of spherical particle confined in a spherical shell". International Journal of Modern Physics B 30, n. 11 (28 aprile 2016): 1650065. http://dx.doi.org/10.1142/s021797921650065x.
Testo completoAbstract (sommario):
The aggregation process of spherical particles confined in a spherical shell was studied by using a diffusion-limited cluster–cluster aggregation (DLCA) model. The influence of geometrical confinement and wetting-like properties of the spherical shell walls on the particle concentration profile, aggregate structure and aggregation kinetics had been explored. The results show that there will be either depletion or absorption particles near the shell walls depending on the wall properties. It is observed that there are four different types of density distribution which can be realized by modifying the property of the inner or outer spherical shell wall. In addition, the aggregate structure will become more compact in the confined spherical shell comparing to bulk system with the same particle volume fraction. The analysis on the aggregation kinetics indicates that geometrical confinement will promote the aggregation process by reducing the invalid movement of the small aggregates and by constraining the movement of those large aggregates. Due to the concave geometrical characteristic of the outer wall of the spherical shell, its effects on the aggregating kinetics and the structure of the formed aggregates are more evident than those of the inner wall. This study will provide some instructive information of controlling the density distribution of low-density porous polymer hollow spherical shells and helps to predict gel structures developed in confined geometries.
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Vetter, Philipp, Susan J. Goodbody e Daniel M. Wolpert. "Evidence for an Eye-Centered Spherical Representation of the Visuomotor Map". Journal of Neurophysiology 81, n. 2 (1 febbraio 1999): 935–39. http://dx.doi.org/10.1152/jn.1999.81.2.935.
Testo completoAbstract (sommario):
Evidence for an eye-centered spherical representation of the visuomotor map. During visually guided movement, visual coordinates of target location must be transformed into coordinates appropriate for movement. To investigate the representation of this visuomotor coordinate transformation, we examined changes in pointing behavior induced by a local visuomotor remapping. The visual feedback of finger position was limited to one location within the workspace, at which a discrepancy was introduced between the actual and visually perceived finger position. This remapping induced a change in pointing that extended over the entire workspace and was best captured by a spherical coordinate system centered near the eyes.
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Ming-zhi, Liu, Shen Yu-ru, Liu Jun e Na Bai. "Mechanical analysis of orbit tracking movement of feed system in large spherical radio-telescope". Applied Mathematics and Mechanics 26, n. 9 (settembre 2005): 1197–203. http://dx.doi.org/10.1007/bf02507730.
Testo completo
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Toyama, Shigeki. "Spherical Ultrasonic Motor for Pipe Inspection Robot". Applied Mechanics and Materials 186 (giugno 2012): 3–11. http://dx.doi.org/10.4028/www.scientific.net/amm.186.3.
Testo completoAbstract (sommario):
We present a pipe inspection robot using a newly developed spherical ultrasonic motor (SUSM) as a camera actuator. The novel SUSM has improved the range of movement compared to previous SUSMs, and the robot can point a camera in any direction. In this study, we determined a method for controlling the rotational direction and strategic control from the kinematics and characteristics of ultrasonic motors. The rotational directions were defined by the phase differences of the applied voltages, and the rotational speeds were changed with the frequencies. Additionally, we developed a very small position sensing system using rotary potentiometers. In the control experiment performed using the sensing system, the SUSM showed the returnability to the default position from several specified points, within an accuracy of 1°.
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Komarov, S. S., N. I. Miskaktin e N. Yu Tsvileneva. "Landing of descent objects with a closed spherical pneumatic shock absorber". Proceedings of the Mavlyutov Institute of Mechanics 3 (2003): 60–71. http://dx.doi.org/10.21662/uim2003.1.004.
Testo completoAbstract (sommario):
The landing of the landing object with a closed pneumatic shock absorber is considered. A mathematical model of planting the ”object–pneumatic shock absorber“ system is being constructed. Nonlinear boundary conditions in the sealing of the pneumatic shock absorber on the body of the landing object and in the area of interaction with the screen in the power structures in the ”object–pneumatic shock absorber“ movement system.
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Bai, Jie, e Jian Jun Dang. "Design and Analysis of a New Type of Spherical Robot". Applied Mechanics and Materials 556-562 (maggio 2014): 2414–17. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.2414.
Testo completoAbstract (sommario):
A new type of spherical robot based on the concept of changing the barycenter of the system is presented. The robot is consist of a shell and inner driving unit inside. The driving motor can provide the torque to move forward and backward, and the other motor can control the movement of a slider which is used to change the barycenter when turning the direction. The whole system is easy to design and the plate inside can be installed with certain sensor for special tasks. The dynamic model of the robot is introduced. The simulation results which shows the accordance with the experiment is presented.
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Vashchilina, O. V., I. V. Lebedyeva e O. I. Bilobrytska. "Modeling and numerical research of the self-excitation phenomenon of the drill bit whirlings vibrations". Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, n. 1 (2019): 28–33. http://dx.doi.org/10.17721/1812-5409.2019/1.5.
Testo completoAbstract (sommario):
In the paper an initial stage of a rotating drill string bit whirl motion proceeding on a well bottom surface is studied on the basis of nonholonomic kinematic models of mechanic interaction between the contacting uneven bodies. It is assumed that the drill bit is an absolutely rigid spherical body, the well bottom surface is spherical too. It is supposed that the system coaxiality is disturbed through small initial curvature of the drill string, defects of the bit and bore-well geometry or the debalance of the system mass. Linearized equations of the drill bit movement are derived, the frequencies of periodic motions are calculated, and their types are constructed for different geometric parameters of the spherical bits. It is shown that, depending on the system properties, the drill bit motion can to transit to the state of stationary spinning relative to an immovable center of velocities or acquire the regimes of forward and backward whirlings.
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He, Zhenqiang, Tong Wang, Xiaolong Wang, Shang Lu, Huachang Liu, Xiao Li, Lingling Men et al. "A new laser-based monitoring method for the cryomodule components alignment". Measurement Science and Technology 33, n. 7 (21 aprile 2022): 075201. http://dx.doi.org/10.1088/1361-6501/ac656b.
Testo completoAbstract (sommario):
Abstract Alignment of superconducting cavities is one of the important issues for the China Spallation Neutron Source Phase II (CSNS II) linac. In order to obtain the cavity displacement in the process of cooling down to the liquid helium temperature, a laser-based Poisson Spot Monitor (PSM) system was newly proposed and a verification system in the laboratory was built. The PSM system uses the diffraction spot formed on the CMOS camera after a beam of parallel laser passes through a spherical target to monitor the position of the measured object, where the spherical target is fixed on the monitored object. The displacement during the cooling process of the cryomodule is replaced by the movement of the high-precision two-axis motorized translation stage. A spherical target is fixed on the translation stage as the monitoring object. A beam of parallel laser passes through the spherical monitoring target to form a Poisson spot image on a CMOS camera. The coordinates of the Poisson spot center are obtained through image processing. Through experiments, the PSM system obtained a high accuracy within 5 μm, which meets the displacement monitoring requirement of the CSNS II cryomodule components. The system is fairly simple and able to be constructed without highly specialized parts and can also be used in other high-precision alignment and monitoring fields.
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Souza, Kleymilson, Ricardo Pontes, Andressa Oliveira e Guilherme Barreto. "Design and Control of a Three-Coil Permanent Magnet Spherical Motor". Energies 11, n. 8 (2 agosto 2018): 2009. http://dx.doi.org/10.3390/en11082009.
Testo completoAbstract (sommario):
The permanent magnet (PM) spherical motor has been subject to growing interest from the scientific community due to its potential for applications in distinct areas, particularly in robotics, prosthetics, satellite control, sensors or camera systems. Motivated by this movement, the current work presents all the steps for the efficient design and construction of a spherical motor model, using compound deposition technology with the aid of a 3D printer. Furthermore, we report comprehensive studies on the accuracy of the positioning system of the proposed motor using only three stator coils, which jointly act to move the rotor axis toward any point in the hemisphere. Unmodeled nonlinear phenomena, such as friction, impair accurate positioning of the motor actuator, but this is solved by means of a visual servo control system, which allows the user to collect input–output data to train an artificial neural network model. Details on the construction of the proposed motor are reported, in addition to the numerical results of the positioning control in tracking a desired trajectory.
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Cameron, Lisa A., Jennifer R. Robbins, Matthew J. Footer e Julie A. Theriot. "Biophysical Parameters Influence Actin-based Movement, Trajectory, and Initiation in a Cell-free System". Molecular Biology of the Cell 15, n. 5 (maggio 2004): 2312–23. http://dx.doi.org/10.1091/mbc.e03-12-0913.
Testo completoAbstract (sommario):
Using a biochemically complex cytoplasmic extract to reconstitute actin-based motility of Listeria monocytogenes and polystyrene beads coated with the bacterial protein ActA, we have systematically varied a series of biophysical parameters and examined their effects on initiation of motility, particle speed, speed variability, and path trajectory. Bead size had a profound effect on all aspects of motility, with increasing size causing slower, straighter movement and inhibiting symmetry-breaking. Speed also was reduced by extract dilution, by addition of methylcellulose, and paradoxically by addition of excess skeletal muscle actin, but it was enhanced by addition of nonmuscle (platelet) actin. Large, persistent individual variations in speed were observed for all conditions and their relative magnitude increased with extract dilution, indicating that persistent alterations in particle surface properties may be responsible for intrinsic speed variations. Trajectory curvature was increased for smaller beads and also for particles moving in the presence of methylcellulose or excess skeletal muscle actin. Symmetry breaking and movement initiation occurred by two distinct modes: either stochastic amplification of local variation for small beads in concentrated extracts, or gradual accumulation of strain in the actin gel for large beads in dilute extracts. Neither mode was sufficient to enable spherical particles to break symmetry in the cytoplasm of living cells.
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Novikov, V. V., e L. N. Fevralskikh. "APPLICATION OF THE APPARATUS OF BALL VECTORS IN PROBLEMS OF MECHANICS". Problems of strenght and plasticity 82, n. 3 (2020): 317–27. http://dx.doi.org/10.32326/1814-9146-2020-82-3-317-327.
Testo completoAbstract (sommario):
An approach to solving problems of dynamics of distributed mechanical systems with spherical symmetry based on the use of the ball vector apparatus is demonstrated. A number of problems of the dynamics of a solid deformable body, liquid fluid, and magnetic hydrodynamics are presented, for which an analytical solution is obtained that allows us to identify qualitative features of the dynamics of the studied objects. The problem of free angular movements of a deformable body close in shape to a ball is considered. The example of almost of ball possessing cubic symmetry, body shape and almost spherical the inertia tensor in the undeformed condition, demonstrates the ability of the global movement in the body axis of steady rotation (pole). The effect is due to the fact that when a body rotates at high speed, the elastic properties play a decisive role in its dynamics. Over time, the angular velocity of the drag decreases and the movement of the body is increasingly affected by its ellipsoidplicity. The motion of an incompressible viscous fluid in the space between a rotating non-concentric sphere and an ellipsoid is studied. It is shown that the asymmetry of the flow leads to the appearance of a radial flow of the liquid. The presence of such a flow in the case of a conducting liquid is a necessary condition for generating a magnetic field. Assuming that the liquid is conductive, a study of the possibility of generating a magnetic field is carried out on the basis of the obtained flow in the framework of the kinematic approach. The smallest value of the Reynolds magnetic number is found, which creates an exponentially growing magnetic field when passing through it. The results obtained can be useful for studying the dynamics of the Earth and the planets of the Solar system and the mechanism of generating a geomagnetic field.
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Vasantha Gowri, N., M. Ramalinga Raju e B. P.Singh. "Analysis of Partial Discharge Due to Movement of Spherical Particle in Power Transformer Using Computational Fluid Dynamics". International Journal of Engineering & Technology 7, n. 3.3 (21 giugno 2018): 73. http://dx.doi.org/10.14419/ijet.v7i3.3.14489.
Testo completoAbstract (sommario):
Power transformer is costly and very important equipment in power sector. Failure of power transformer causes colossal damage to the power system. One of the important reasons for transformer failure is event of Partial Discharge (PD) in the transformer. Numbers of non-conducting and conducting particle are available in the transformer. Conducting particles available in the transformer or mineral oil entering into winding space, strike the energized winding of the transformer cause PD to occur. Movement pattern of particle administrates the probability of particle striking the winding. Analysis of movement of particles proximate to HV winding helps in understanding the occurrence of PD. This paper deals with tracking of aluminum and copper particles of various sizes available inside the transformer.
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Sisworo, Raden Rinova, Masato Hasegawa, Kousuke Nakashima, Yu Norimatsu e Yukio Tada. "Generation of Monodispersed Spherical Thermosensitive Gels and Their Swelling and Shrinking Behaviors in Aqueous Polymeric Solutions". Applied Sciences 10, n. 6 (16 marzo 2020): 2016. http://dx.doi.org/10.3390/app10062016.
Testo completoAbstract (sommario):
This study investigates the factors affecting the formation of monodispersed thermosensitive gels and the parameters influencing the movement of gel particles containing N-isopropyl acrylamide in an aqueous polymeric solution in an upper heating system. Monodispersed thermosensitive gels were generated, and their swelling and shrinking behaviors were observed. The results revealed that continuous-phase flow rate and kinematic viscosity were most influential on the size of the monodispersed thermosensitive gels, which exhibited swelling and shrinking at both low and high temperatures of the polymeric aqueous solution, respectively, and demonstrated negative thermal expansion. In a low-temperature solution, the buoyancy force acting on the gel particles exceeded the gravitational force, because of which the size of the gels increased and the gels to ascended. At higher temperatures, the gels shrank because the gravitational force outweighed the buoyancy force, causing the gels to descend. The gels with a larger diameter tended to have longer durations of vertical movements within the aqueous polymeric solution than the smaller-sized gels; moreover, equilibrium conditions were quickly achieved by the smaller gels.
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Yao, Ying Xue, Yue Dong Lang, Ping Jun Xia, Peng Chen e Guo Hua Liu. "Realization Technology of A New Virtual Environment for Large-Scale Complex Products Assembly". Key Engineering Materials 431-432 (marzo 2010): 305–8. http://dx.doi.org/10.4028/www.scientific.net/kem.431-432.305.
Testo completoAbstract (sommario):
To deal with the problems of complicated process, difficult operation and low efficiency for large-scale complex products assembly, a new immersive virtual environment (VE) with virtual reality (VR) technology is built in the process of assembly planning and training. The environment is composed of a free walk machine and spherical screen projection system. In this paper, a free walk machine with movement perception function is developed to achieve natural human-computer interaction. And an approach based on two viewpoints match is adopted to improve immersive effect of stereo projection in the projection system. On the basis of that, a geometry calibration method based on Bicubic NURBS(Non-Uniform Rational B-Spline) surface matching target-controlled dot-matrix is proposed to achieve non-distorted image on spherical screen. Finally, the environment is applied in the process of satellite assembly process planning, and the display result shows that the VE development is feasible and valuable.
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Aoyama, Kazuma, Kiyosu Maeda, Ryoko Ueoka, Shigeo Makioka, Nobukazu Sakura, Kunihiko Nakashima, Michitaka Hirose e Tomohiro Amemiya. "Improving Remote Spatial Understanding by Transmitting Spherical Images via Video Chat Applications". International Journal of Automation Technology 16, n. 3 (5 maggio 2022): 286–95. http://dx.doi.org/10.20965/ijat.2022.p0286.
Testo completoAbstract (sommario):
Manufacturing functions are often performed by groups of engineers who cooperate and gather at work sites. However, since the beginning of the COVID-19 pandemic, the movement and activities of groups of people have been restricted, especially in indoor spaces. This reduction in travel by engineers also implies a reduction in associated costs. Telepresence technology, which is studied in the field of virtual reality, can be used as a way to reduce travel. Telepresence allows users to engage with a site from a remote location as if they were present. Thus, engineers would be able to participate in a working group without the necessity of physically traveling to the site to cooperate with local manufacturing people. A variety of telepresence systems have been proposed; however, relatively few methods have been widely implemented compared with video chat applications that have recently become an established infrastructure in many companies. This is most likely because most proposed systems use robots, head-mounted displays, or dedicated multi-functional applications that require engineers to learn how to use them. One way to use a video chat application to understand a remote space is to have a remote participant move a camera used in a video chat application. In contrast, many VR social networking services use a viewing method with which users can change their viewing direction on the computer screen. In this study, we demonstrate that a system that allows users to rotate their viewing perspective on a laptop computer screen can provide an easier understanding of a virtual space than a system that requires a remote person to move a webcam. Based on these results, we propose a system that allows users to view a remote location on a laptop computer screen via a video chat application and an off-the-shelf spherical camera, and evaluate its usefulness.
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BERTHONNAUD, ERIC, e JOANNÈS DIMNET. "A NEW TECHNIQUE ESTIMATING LOCATION OF MEAN JOINT CENTERS OF ROTATION WITH ASSOCIATED DISPERSIONS AND ASSESSING TO FUNCTIONAL COORDINATE SYSTEM OF MOVING LIMB SEGMENTS". Journal of Mechanics in Medicine and Biology 06, n. 04 (dicembre 2006): 373–84. http://dx.doi.org/10.1142/s0219519406001996.
Testo completoAbstract (sommario):
Joint centers are obtained from data treatment of a set of markers placed on the skin of moving limb segments. Finite helical axis (FHA) parameters are calculated between time step increments. Artifacts associated with nonrigid body movements of markers entail ill-determination of FHA parameters. Mean centers of rotation may be calculated over the whole movement, when human articulations are likened to spherical joints. They are obtained using numerical technique, defining point with minimal amplitude, during joint movement. A new technique is presented. Hip, knee, and ankle mean centers of rotation are calculated. Their locations depend on the application of two constraints. The joint center must be located next to the estimated geometric joint center. The geometric joint center may migrate inside a cube of possible location. This cube of error is located with respect to the marker coordinate systems of the two limb segments adjacent to the joint. Its position depends on the joint and the patient height, and is obtained from a stereoradiographic study with specimen. The mean position of joint center and corresponding dispersion are obtained through a minimization procedure. The location of mean joint center is compared with the position of FHA calculated between different sequential steps: time sequential step, and rotation sequential step where a minimal rotation amplitude is imposed between two joint positions. Sticks are drawn connecting adjacent mean centers. The animation of stick diagrams allows clinical users to estimate the displacements of long bones (femur and tibia) from the whole data set.
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Liu, Manlu, Rui Lin, Maotao Yang, Anaid V. Nazarova e Jianwen Huo. "Active disturbance rejection motion control of spherical robot with parameter tuning". Industrial Robot: the international journal of robotics research and application 49, n. 2 (23 novembre 2021): 332–43. http://dx.doi.org/10.1108/ir-05-2021-0099.
Testo completoAbstract (sommario):
Purpose The characteristics of spherical robots, such as under-drive, non-holonomic constraints and strong coupling, make it difficult to establish its motion control model accurately. To improve the anti-interference performance of spherical robots in practical engineering, this paper proposes a spherical robot motion controller based on auto-disturbance rejection control (ADRC) with parameter tuning. Design/methodology/approach This paper considers the influences of the spherical shell, internal frame and pendulum on the movement of the spherical robot during the rotation to establish the multi-body dynamics model of the XK-I spherical robot. Due to the serious coupling problem of the dynamic model, the motion control state equation is constructed using linearization and decoupling. The XK-I spherical robot PSO-ADRC motion controller with parameter tuning function is designed by combining the state equation with the particle swarm optimization (PSO) algorithm. Finally, experiments are performed to evaluate the feasibility of PSO-ADRC in an actual case compared to ADRC, PSO-PID and PID. Findings By analyzing the required time to reach the expected value, the control stability and the fluctuation range of the standard deviation after reaching the expected value, the superiority of PSO-ADRC to ADRC, PSO-PID and PID is demonstrated in terms of the speed and anti-interference ability. Practical implications The proposed method can be applied to the robot control field. Originality/value A parameter-tuning method for auto-disturbance-rejection motion control of the spherical robot is proposed. According to the experimental results, the anti-interference ability of the spherical robot moving on uneven ground is improved. Therefore, it provides a foundation for the autonomous environmental monitoring of the spherical robot equipped with sensors.
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Meeker, David C., e Miles A. Townsend. "Motions of a Powered Top with a Spherical Tip on a Curved Surface". Shock and Vibration 2, n. 1 (1995): 23–32. http://dx.doi.org/10.1155/1995/697496.
Testo completoAbstract (sommario):
The purpose of this article is to model the dynamics of a top with a finite radius tip on a curved basin in a gravitational field without (and with) energy addition and dissipation. This is an extension of a very general and classical problem and requires development of a method for treating the dynamical interactions between the two curved surfaces. The full nonlinear equations of motion are indicated; however, these equations are complex and do not show the dominant mechanisms that define the system motions. A novel method of “partial linearization” is employed that reduces the equations of motion to a relevant and tractable form in which these mechanisms are clearly exposed. The model and related results are compared with relevant examples from the literature. The movement of the top is simulated by an integration of the fully nonlinear equations of motion and compared with the partially linearized results.
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Miftakhova, Almira, Yang-Yuan Chen e Jeng-Haur Horng. "Effect of rolling on the friction coefficient in three-body contact". Advances in Mechanical Engineering 11, n. 8 (agosto 2019): 168781401987230. http://dx.doi.org/10.1177/1687814019872303.
Testo completoAbstract (sommario):
The contact problem of system of particles rolling over a viscoelastic layer bonded to the rigid half-space was considered. Particles have a spherical shape and their radiuses are distributed along Gauss. Earlier, the friction coefficient was obtained for the particles between surfaces in the relative movement of the surfaces using the three-body interaction method. In this study, the contact area was calculated for a system of particles rolling over the viscoelastic layer bonded to the half-space. Using the three-body interaction approach, the friction coefficient was calculated, taking into account the rolling of particles. The results demonstrate that the coefficient of friction, calculated using the three-body model, decreases when the rolling of particles is taken into account.
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Vilhena, Luís, Fábio Ferreira, João Carlos Oliveira e Amílcar Ramalho. "Rapid and Easy Assessment of Friction and Load-Bearing Capacity in Thin Coatings". Electronics 11, n. 3 (18 gennaio 2022): 296. http://dx.doi.org/10.3390/electronics11030296.
Testo completoAbstract (sommario):
The present research paper aims to evaluate the tribological behavior of coatings in applications where high wear resistance and low friction are required, commonly used in refurbishment of various items of industrial equipment. Twelve tribological pairs made of six different coatings, corresponding to three different coating families, have been studied: TiSiN, Cr, and DLC (diamond-like carbon). The coatings were produced using a technique called high power impulse magnetron sputtering (HiPIMS). To perform the tribological tests, two methods were used to measure friction, namely energy dissipation in vibratory systems and sliding indentation. The first technique is based on the evaluation of free vibration movement with damping of a mass–spring system induced by a mechanical impulse where the contact between the vibrating device and the sample to be analyzed acts as an additional energy dissipation. At the same time, friction is determined through the inverse analysis by comparing the experimental vibratory movement with the analytical equation of the movement. The determination of the load-bearing capacity of the various coatings has been evaluated using sliding indentation tests against spherical bodies using a constant sliding speed and increasing normal loads. The results obtained in both tests allow to verify a relationship between the friction coefficients of the studied tribological pairs: µDLC < µTiSiN < µCr. This relationship does not occur in the case of the vibration test with the 100Cr6 counter-body.
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Filimonova, Olga N., Marina V. Enyutina, Anatoly A. Khvostov e Viktor I. Ryashskih. "MODELING PROCESS OF DESTRUCTION OF PARTICLES OF CEMENT AT INITIAL STAGE OF HYDRATION". IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 62, n. 11 (20 novembre 2019): 138–42. http://dx.doi.org/10.6060/ivkkt.20196211.5986.
Testo completoAbstract (sommario):
The substantiation the existence of the destruction period of cement particles during the hydration of concrete into fragments, in size significantly larger than the average size of molecules is presented. An idealized structure of the cell representation for the cement grain and the water surrounding it in the form of nested spheres is adopted. The outer sphere does not change its coordinates, and the inner sphere imitating the cement grain decreases in the course of the process due to the transfer of the formed fragments into the inter-spherical space filled with water. The assumption is made that the concentration field is uniform and varies along the radius. The crushing process is described using a physical model of "pseudo-dissolution" and is based on the formulation of Fick's law. By introducing the rate of destruction associated with the movement of the interfacial boundary, a mathematical model is formulated in the form of an initial boundary value problem for the diffusion-type equation in a spherical coordinate system. By introducing a special coordinate system, the formulated initial-boundary value problem is transformed into a problem with fixed boundaries. Integration of the obtained system is performed numerically using an explicit finite-difference scheme. The computational experiment confirmed the efficiency of the proposed algorithm, which allowed to conduct a qualitative analysis of the model, which showed the correctness of the assumptions made in the formulation of the mathematical model. It is found that in a spherical cell containing an average cement grain, the fragments are localized near the interfacial surface due to the weak influence of the diffusion transfer mechanism. The estimation of the average size of the fragments, which are significantly larger than the average molecular size, further confirmed the hypothesis of the existence of the period of destruction of cement grains in the initial stage of concrete hydration.
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Starinova, O. L., E. A. Sergaeva e A. Yu Shornikov. "Design and ballistic analysis of the mission for long-term study of the asteroid Apophis by a nanosatellite with an electric rocket propulsion system". Spacecrafts & Technologies 4, n. 3 (settembre 2020): 161–70. http://dx.doi.org/10.26732/j.st.2020.3.04.
Testo completoAbstract (sommario):
The paper considers non-spherical objects with low gravitational attraction, such as asteroids, satellites of the planet and comets. We considered possibility of a mission to small bodies of the solar system of irregular shape on the example of the asteroid Apophis. The authors of the article suggest using a nanoclass spacecraft with an electric rocket propulsion system for a long mission to study Apophis. The purpose of this work is to determine the necessary costs of the working body for all stages of the mission, which includes reaching the asteroid, forming and maintaining a given orbit relative to it. The gravity of the Earth, Sun, and asteroid is taken into account when modeling the controlled movement of the spacecraft. When a spacecraft is moving relative to an asteroid, its gravitational field is described as a superposition of the gravitational fields of two rotating massive points. In this paper, it is proposed to divide the mission into two sections for preliminary ballistic design. The first optimal speed heliocentric flight Earth-asteroid Apophis with the alignment of the speed of the spacecraft and the asteroid. The second is the movement in the vicinity of the asteroid, which includes the optimal speed maneuver for forming the working orbit and maintaining the working orbit for a given time.
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Buriy, G. G. "Mathematical model of soil digging spherical excavator bucket". Russian Automobile and Highway Industry Journal 18, n. 6 (17 gennaio 2022): 688–98. http://dx.doi.org/10.26518/2071-7296-2021-18-6-688-698.
Testo completoAbstract (sommario):
Introduction. The article presents a new design of a bucket of a single bucket hydraulic excavator, which allows you to increase the performance of these machines. Increased efficiency is achieved due to the installation of buckets of larger volume without changing characteristics of hydraulic drive. The purpose of the presented work is to select the volume of the spherical ladle for the digging process. The task of research is to obtain the dependencies of ladle and soil speeds on the parameters of the digging process. Selecting the volume of the spherical ladle will determine how much it can be increased compared to the volume of the serial ladle to carry out the digging process.Materials and methods. The process of digging a new bucket was considered in the form of a two-scale KelvinVoigt rheology model. This model was described by a system of second-order differential equations. The system solved the Cauchy problem, which made it possible to determine the general solution of the equation satisfying the two equations of the system. As a result, derivatives from ladle and soil movements were determined, which are nothing more than ladle and soil speeds.Results. The solution of the above system made it possible to obtain dependencies of ladle speeds and soil masses on parameters of the digging process. The digging process is possible at positive speed values. When substituting depending on the process parameters under the condition of velocity positivity, you can determine the volume of the spherical ladle.Practical significance. To simplify and put into practice the obtained dependencies, an algorithm was compiled to calculate the volume of the spherical ladle. The presented algorithm can be implemented in a computer program.
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Jatsun, S. F., О. G. Loktionova, L. Yu Vorochaeva e О. V. Emelianova. "DESIGN AND CONTROL SYSTEM OF THE ROBOT ORNITHOPTER, EQUIPPED WITH WINGS AND TAIL". Proceedings of the Southwest State University 22, n. 2 (28 aprile 2018): 18–26. http://dx.doi.org/10.21869/2223-1560-2018-22-2-18-26.
Testo completoAbstract (sommario):
The paper deals with the ornithopter flight which simulates the flight of a bird. The robot consists of a body, two folding wings and a tail. The ornithopter roll is provided by wing swings, and pitch and yaw are provided by twists of the tail in two planes. When switching to the design scheme of the device, each wing is replaced by two links connected to each other and to the body by means of cylindrical hinges, the axes of all hinges are parallel to the longitudinal axis of the robot. Two mechanisms are used to implement swings in the device. One of them (the mechanism of swings) directly provides fluctuations in the wings relative to the body, as well as changing their area by adding when moving up and decomposition when moving down. This mechanism consists of a motor and crank-rod-rocker mechanism. The second mechanism (rotation of the ailerons on the wings) allows the wings in addition to flapping additionally to flex during motion, thereby "pocketing" of the air and the extra control area of the wings: its decrease with the movement of the wings up and the increase in the movement of the wings down. The tail is connected to the body due to the spherical hinge and two crank mechanisms. With the help of one of the mechanisms the tail rotates relative to the longitudinal axis of the body in the horizontal plane, and with the help of the other - in the vertical. For this robot a flight control system is proposed, which provides the robot movement along a given trajectory. The control system includes a control unit and a control device (ornithopter). The control unit is formed by modules specifying the effects and calculation of angles, as well as comparator and controller. The control device includes drives, links (wings and tail) and the robot body. Management is carried out on six generalized coordinates determining the position and orientation of the hull in space. For this purpose, eight feedbacks are used in the angles of rotation of the wings and the tail of the robot relative to its body.
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Kwon, Yong-Bin, Ji-Hyun Kang, Chang-Soo Han, Dong-Wook Kim e Chun-Woong Park. "The Effect of Particle Size and Surface Roughness of Spray-Dried Bosentan Microparticles on Aerodynamic Performance for Dry Powder Inhalation". Pharmaceutics 12, n. 8 (13 agosto 2020): 765. http://dx.doi.org/10.3390/pharmaceutics12080765.
Testo completoAbstract (sommario):
The purpose of this study was to prepare spray dried bosentan microparticles for dry powder inhaler and to characterize its physicochemical and aerodynamic properties. The microparticles were prepared from ethanol/water solutions containing bosentan using spray dryer. Three types of formulations (SD60, SD80, and SD100) depending on the various ethanol concentrations (60%, 80%, and 100%, respectively) were used. Bosentan microparticle formulations were characterized by scanning electron microscopy, powder X-ray diffraction, laser diffraction particle sizing, differential scanning calorimetry, Fourier-transform infrared spectroscopy, dissolution test, and in vitro aerodynamic performance using Andersen cascade impactor™ (ACI) system. In addition, particle image velocimetry (PIV) system was used for directly confirming the actual movement of the aerosolized particles. Bosentan microparticles resulted in formulations with various shapes, surface morphology, and particle size distributions. SD100 was a smooth surface with spherical morphology, SD80 was a rough surfaced with spherical morphology and SD60 was a rough surfaced with corrugated morphology. SD100, SD80, and SD60 showed significantly high drug release up to 1 h compared with raw bosentan. The aerodynamic size of SD80 and SD60 was 1.27 µm and SD100 was 6.95 µm. The microparticles with smaller particle size and a rough surface aerosolized better (%FPF: 63.07 ± 2.39 and 68.27 ± 8.99 for SD60 and SD80, respectively) than larger particle size and smooth surface microparticle (%FPF: 22.64 ± 11.50 for SD100).
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An, Ruochen, Shuxiang Guo, Yuanhua Yu, Chunying Li e Tendeng Awa. "Multiple Bio-Inspired Father–Son Underwater Robot for Underwater Target Object Acquisition and Identification". Micromachines 13, n. 1 (26 dicembre 2021): 25. http://dx.doi.org/10.3390/mi13010025.
Testo completoAbstract (sommario):
Underwater target acquisition and identification performed by manipulators having broad application prospects and value in the field of marine development. Conventional manipulators are too heavy to be used for small target objects and unsuitable for shallow sea working. In this paper, a bio-inspired Father–Son Underwater Robot System (FURS) is designed for underwater target object image acquisition and identification. Our spherical underwater robot (SUR), as the father underwater robot of the FURS, has the ability of strong dynamic balance and good maneuverability, can realize approach the target area quickly, and then cruise and surround the target object. A coiling mechanism was installed on SUR for the recycling and release of the son underwater robot. A Salamandra-inspired son underwater robot is used as the manipulator of the FURS, which is connected to the spherical underwater robot by a tether. The son underwater robot has multiple degrees of freedom and realizes both swimming and walking movement modes. The son underwater robot can move to underwater target objects. The vision system is installed to enable the FURS to acquire the image information of the target object with the aid of the camera, and also to identify the target object. Finally, verification experiments are conducted in an indoor water tank and outdoor swimming pool conditions to verify the effectiveness of the proposed in this paper.
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Cutting, James E. "Images, Imagination, and Movement: Pictorial Representations and Their Development in the Work of James Gibson". Perception 29, n. 6 (giugno 2000): 635–48. http://dx.doi.org/10.1068/p2976.
Testo completoAbstract (sommario):
For more than 30 years James Gibson studied pictures and he studied motion, particularly the relationship between movement through an environment and its visual consequences. For the latter, he also struggled with how best to present his ideas to students and fellow researchers, and employed various representations and formats. This article explores the relationships between the concepts of the fidelity of pictures (an idea he first promoted and later eschewed) and evocativeness as applied to his images. Gibson ended his struggle with an image of a bird flying over a plane surrounded by a spherical representation of a vector field, an image high in evocativeness but less than completely faithful to optical flow.
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Yue, Ming, Baoyin Liu, Cong An e Xiaojie Sun. "Extended state observer-based adaptive hierarchical sliding mode control for longitudinal movement of a spherical robot". Nonlinear Dynamics 78, n. 2 (24 giugno 2014): 1233–44. http://dx.doi.org/10.1007/s11071-014-1511-1.
Testo completo
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Aparicio-García, Cristina Tehaní, Edisson A. Naula Duchi, Luis E. Garza-Castañón, Adriana Vargas-Martínez, J. Israel Martínez-López e Luis I. Minchala-Ávila. "Design, Construction, and Modeling of a BAUV with Propulsion System Based on a Parallel Mechanism for the Caudal Fin". Applied Sciences 10, n. 7 (2 aprile 2020): 2426. http://dx.doi.org/10.3390/app10072426.
Testo completoAbstract (sommario):
Traditional propulsion systems for autonomous underwater vehicles (AUVs) have several deficiencies, such as the invasion of the aquatic environment through the generation of noise and damage to the ecosystem, higher energy consumption, and a unidirectional thruster vector. The last characteristic constrains the maneuverability of the vehicle. This paper proposes a 3-DOF spherical 3 universal–cylindrical–universal and 1 spherical joint (3UCU-1S) parallel mechanism coupled to an artificial caudal fin to produce a vectored thruster for a biomimetic AUV (BAUV). First, the design and construction of the prototype are described. Then, the kinematics and dynamics analysis of the parallel mechanism is presented. Finally, a motion study shows the types of movements that can be achieved with the mechanism to perform flapping of the caudal fin in different directions.
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Gaponova, L. V., e S. S. Grebenchuk. "STRESS AND STRAIN BEHAVIOUR OF REINFORCED CONCRETE ANISOTROPIC SHELLS". ACADEMIC JOURNAL Series: Industrial Machine Building, Civil Engineering 1, n. 48 (27 marzo 2017): 108–20. http://dx.doi.org/10.26906/znp.2017.48.784.
Testo completoAbstract (sommario):
The character changes deflected mode of «Monofant» system fragments. For experimental studies state snippets new structural system of “Monofant” multi conformity was deformed and method based on hydrostatic load when the load is given by the weight of water, was used, and its value is governed by the height of the water column. To determine the qualitative and quantitative research object deformation measurements displacement cylindrical and spherical shells in 25 points was carried. However, the configuration structure complexity was given, which in turn led to the emergence of both vertical and horizontal movements of the studied surface shell under vertical load, the need to measure movements in two directions in a cylindrical shell of vertical displacement and a spherical shell. The study shows that the structural elements are endowed with all the necessary strength characteristics and attributes rigidity bearing elements of reinforced concrete buildings.
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Gündoğar, Umut Yusuf, e Sibel Zorlu Partal. "Design, 3D FEM Simulation and Prototyping of a Permanent Magnet Spherical Motor". Actuators 10, n. 11 (21 novembre 2021): 305. http://dx.doi.org/10.3390/act10110305.
Testo completoAbstract (sommario):
In recent years, large tilt angles, uniform magnetic flux distributions, strong forces, and large torques for motors have increasingly become important for robotics, biomedical, and automotive applications that have multi-degrees of freedom (MDOFs) motion. Generally, one-degree of-freedom motors are applied in MDOF motion. These situations cause the systems to have very complex and large structures. In order to address these issues, a 2-DOF surface permanent magnet spherical motor with a new mechanical design for the movement of the rotor with a large tilt angle of ±45° was designed, simulated, produced and tested in this paper. The motor consisted of a 4-pole permanent magnet rotor and a 3-block stator with 18 coils. In this study, the mechanical structure of the proposed spherical permanent magnet motor surrounded the rotor with two moving parts to move at a large tilt angle of ±45° without using any mechanical components such as spherical bearings, joint bearings, and bearing covers. Thus, the tilt angle, force, and torque values of the proposed motor have been improved according to MDOF motion motors using spherical bearings, bearing covers, or joint bearings in their mechanical structures in the literature. Ansys Maxwell software was used for the design and simulation of the motor. Three-dimensional (3D) finite element method (FEM) analysis and experimental studies were carried out on the force, torque, and magnetic flux density distribution of the motor. Then, simulation results and experimental results were compared to validate the 3D FEM simulations results.
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Maloney, Laurence T., e Albert J. Ahumada. "Learning by Assertion: Two Methods for Calibrating a Linear Visual System". Neural Computation 1, n. 3 (settembre 1989): 392–401. http://dx.doi.org/10.1162/neco.1989.1.3.392.
Testo completoAbstract (sommario):
A visual system is geometrically calibrated if its estimates of the spatial properties of a scene are accurate: straight lines are judged straight, angles are correctly estimated, and collinear line segments are perceived to fall on a common line. This paper describes two new calibration methods for a model visual system whose photoreceptors are initially at unknown locations. The methods can also compensate for optical distortions that are equivalent to remapping of receptor locations (e.g., spherical aberration). The methods work by comparing visual input across eye/head movements; they require no explicit feedback and no knowledge about the particular contents of a scene. This work has implications for development and calibration in biological visual systems.
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Lucia, Anda. "UTILIZATION OF SODIUM SULFIT DROPLET FOR OXYGEN ABSORPTION". Scientific Contributions Oil and Gas 41, n. 2 (29 giugno 2020): 89–94. http://dx.doi.org/10.29017/scog.41.2.337.
Testo completoAbstract (sommario):
Gas absorption by liquid droplets in a spray column is one common method for gas cleaning. The simple design, low pressure drop, and the possibility of its application in liquid systems containing solids are benefi ts of this method. The mass transfer coeffi cient of gas-liquid absorption depends on droplet size, concentration of liquid or gas and the physic-chemical system. Experiments to study the mass transfer using the air-oxygen/sulphite system have been performed. The dispersed droplets were generated by pumping the liquid through a needle with certain fl owrate. A High Speed Camera with shadowgraph method and image processing was used for measurement of droplet size and velocity accurately. The shapes of the droplets were relatively not spherical because of oscillating movement. The droplets are slightly accelerated after detach from the needle. The oxygen concentrations were determined by means of spectrophotometric method. The liquid mass transfer coeffi cients of this experiment are 2 times lower than the model because of the low reaction between oxygen and sulphite . The mass transfer coeffi cient of the experiment is calculated from the experimental data, and compared with the model equations from the literature.
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Tolchelnikova, S. A. "Astrometry and Geodesy as a one science. History and assignment of stellar catalogues". Geodesy and Cartography 979, n. 1 (20 febbraio 2022): 40–53. http://dx.doi.org/10.22389/0016-7126-2022-979-1-40-53.
Testo completoAbstract (sommario):
According to the resolution of the International Astronomical Union, since 1999 the main reference for spherical coordinates has become the international celestial reference frame ICRF, compiled from observations of quasars and point-like radio galaxies. This decision abolishes the observations necessary for compiling the traditional spherical coordinate system represented by the fundamental catalogs of the FK series. It is useful to recall the principles of astronomers of the 18th–20th centuries who had organized the determination of the absolute coordinates of stars at the state observatories, required for compiling the next fundamental catalog. This will allow natural scientists who study movements by measured coordinates of celestial objects, firstly astronomers and geodesists, to compare the opportunities provided by optical fundamental catalogs and the reference system of radio coordinates for solving the problems of their branch of science. Let us turn to historical experience, which shows that the establishment of main optical coordinate systems was not a volitional decision but was affirmed in the process of searching for the most effective method for solving both fundamental problems and satisfying current needs of each historical era.
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Mashhadany, Yousif Al. "Hybrid ANFIS Controller for 6-DOF Manipulator with 3D Model". INTERNATIONAL JOURNAL OF COMPUTERS & TECHNOLOGY 4, n. 2 (30 novembre 2005): 631–38. http://dx.doi.org/10.24297/ijct.v4i2c2.4188.
Testo completoAbstract (sommario):
This paper proposes a hybrid ANFIS (Adaptive Neuro-Fuzzy Inference System) controller with DMRAC (Direct Model Reference Adaptive Control) and mathematical modeling of the kinematic and dynamic solutions. The controller was hybrid with a classical controller, and was designed for a spherical-wristed 6-DOF elbow manipulator. The manipulator’s trajectory overshoot and settling time affect movement; their minimization was thus aimed for. The whole manipulator-controller system was modeled and simulated on MATLAB Version 2011a and Robotics Toolbox 9. To increase accuracy, the ANFIS controller was trained to use many paths in rules and memberships selection. A 3D display model for the manipulator was built in MATLAB. The simulation of the design had done by using the MATLAB/SIMULINK through connection the design with 3D model. Satisfactory results show the hybrid controller’s capacity for precision and speed, both of which are higher than a classical controller’s alone.
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Blinov, Alexander О., Andrey V. Borisov, Larisa V. Konchina, Marina G. Kulikova e Ksenia S. Maslova. "Simulation of the movement of the supporting leg of an exoskeleton with two links of variable length in 3D". Journal Of Applied Informatics 16, n. 4 (31 agosto 2021): 122–34. http://dx.doi.org/10.37791/2687-0649-2021-16-4-122-134.
Testo completoAbstract (sommario):
A two-link model of exoskeleton with variable-length links for supporting the lower limbs of the human musculoskeletal system is proposed in the article. The researched model differs from the existing ones by the variable-length links, and by the angle calculation method. While in the existing models, the angles are calculated from the regular direction – from vertical, or from horizontal, – in the proposed research they are calculated between the links. As for practical exoskeleton implementation, the proposed method of angle calculation is appropriate to the actual working conditions of the electrical motors with the reduction gears installed in the hinges, which change the angles between the links. The construction of a variable-length exoskeleton link consists of two absolutely solid weighty sections located at both ends of the link and one weightless section between them in the center of the link. In the weightless section, there is a drive that creates a control longitudinal force, which realizes the increase or decrease in the length of the link in the required manner and provides the necessary maintenance of the length of the link when the person moves in the exoskeleton. The links are connected to each other using spherical hinges. Drives are installed in each hinge, creating control torques, which provide a relative rotational movement of the links. The jointly controlling longitudinal forces and moments realize the maintenance of the posture or the movement of the link in the required manner and, in relation to the exoskeleton, the repetition of the basic biomechanical properties of the human musculoskeletal system. The mathematical model in the form of the system of Lagrange differential equations of the second kind is obtained. The obtained mathematical model is examined for existence and uniqueness of the Cauchy solution. The kinematic trajectory of the link motion has been synthesized, which simulates the anthropomorphic movement of the supporting leg during the single-support phase of movement, and the control actions required for its implementation has been found. The significance of the results obtained in the process of modeling lies in the ability to create active exoskeletons, prostheses in medicine, anthropomorphic robots, and spacesuits that take into account the biomechanical features of the functioning of the human musculoskeletal system.
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Hussain, A. T., S. Faiz Ahmed e D. Hazry. "Tracking and replication of hand movements by teleguided intelligent manipulator robot". Robotica 33, n. 1 (11 febbraio 2014): 141–56. http://dx.doi.org/10.1017/s0263574714000083.
Testo completoAbstract (sommario):
SUMMARYIn this paper, a new method is presented that allows an intelligent manipulator robotic system to track a human hand from far distance in 3D space and estimate its orientation and position in real time with the goal of ultimately using the algorithm with a robotic spherical wrist system. In this proposed algorithm, several image processing and morphology techniques are used in conjunction with various mathematical formulas to calculate the hand position and orientation. The proposed technique was tested on Remote teleguided virtual Robotic system. Experimental results show that proposed method is a robust technique in terms of the required processing time of estimation of orientation and position of hand.
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Gnusov, Maksim, Mikhail Drapalyuk, P. Popikov e N. Sherstyukov. "MODELING THE WORK FLOW OF CUT-OUT SPHERICAL DISKS WITH HYDRAULIC DRIVE FOR FIRE-FIGHTING SOIL-THROWER". Forestry Engineering Journal 10, n. 1 (6 aprile 2020): 185–92. http://dx.doi.org/10.34220/issn.2222-7962/2020.1/23.
Testo completoAbstract (sommario):
In this article, considerable attention is paid to the method of mathematical creation of a structurally complex soil environment with vegetation. Structural and technological parameters of the interaction of the working bodies of the fire-fighting soil thrower with soil have been determined using a simulation-physical-mathematical model of the spherical disk relationship with the soil environment. The disk is equipped with a cutting edge with semicircular cuts. The mathematical model presents complex geometry of all forms of active work planes, as well as the relationship of the working bodies with soil elements. Surfaces of complex construction in the process of applying the finite element method have been transformed into a large number of simplified planar figures. The soil in the simulation physical-mathematical model is described as a complex system of a large number of spherical elements, determinately connecting with each other, as well as with the working planes of the machine. It has been determined that the relationship between the soil particles during deformation is viscoelastic in its nature. The calculation of forces is presented in the form of an algorithm for the interaction of elements on each other in relation to the distance of their location. The equations of motion are used that describe the change in the dynamic state of the soil over time. The movement of the working bodies of the unit, including spherical disk working bodies with cutouts in the framework of the mathematical model, has been considered in the simulated space, described as a parallelepiped. The ability to simulate the interaction of the working bodies of a forest fire soil-throwing machine with a working medium, including plant roots, which are located next to each other in the form of spherical elements in the geometric region. The task of increasing the efficiency of the forest fire-fighting soil-throwing machine when laying fire strips has been solved by improving the quality of preparing the soil shaft with spherical hydraulic disks equipped with a cutting edge with semicircular cuts, which are subsequently taken by thrower-cutters and feed the soil flow in a given direction
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Tyurin, Alexander, Pyotr Zavialov e Alexander Zikov. "NOISE PROTECTION DEVICE DEVELOPMENT FOR LOCAL NOISE CANCELLATION". Akustika 32 (1 marzo 2019): 59–63. http://dx.doi.org/10.36336/akustika20193259.
Testo completoAbstract (sommario):
Currently the noise factors influence on stationary workplaces is prevalent in the other harmful factors influence total share. The information proposed below reveal the gist of the technical solution related to devices for ensuring the workplace acoustic safety. Noise clipping is provided by digital technology. The technical result is expressed in increasing the noise cancellation efficiency in the device upper local zone, so at the user's head level. The device can be used on stationary workplaces, the technological process implementation on which does not require active physical movements. Product using reduces the load on the human auditory system and ensures its protection. Basic expressions are presented that allow noise control in a noisy space between loudspeakers. The noise protection device contains detecting microphones, a control unit for the active noise cancellation process, loudspeakers and a noise shield located on the frame. A specially designed shield is made in the spherical segment form, to the outer edge of which a rim on flexible brackets is attached with the possibility of detecting microphones free movement along it.The device bearing frame is made in a U-shaped form, in the upper part of which the loudspeakers are mounted with diaphragms facing each other.
42
Karadogan, Ernur, e Robert L. Williams. "The Robotic Lumbar Spine: Dynamics and Feedback Linearization Control". Computational and Mathematical Methods in Medicine 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/985248.
Testo completoAbstract (sommario):
The robotic lumbar spine (RLS) is a 15 degree-of-freedom, fully cable-actuated robotic lumbar spine which can mimicin vivohuman lumbar spine movements to provide better hands-on training for medical students. The design incorporates five active lumbar vertebrae and the sacrum, with dimensions of an average adult human spine. It is actuated by 20 cables connected to electric motors. Every vertebra is connected to the neighboring vertebrae by spherical joints. Medical schools can benefit from a tool, system, or method that will help instructors train students and assess their tactile proficiency throughout their education. The robotic lumbar spine has the potential to satisfy these needs in palpatory diagnosis. Medical students will be given the opportunity to examine their own patient that can be programmed with many dysfunctions related to the lumbar spine before they start their professional lives as doctors. The robotic lumbar spine can be used to teach and test medical students in their capacity to be able to recognize normal and abnormal movement patterns of the human lumbar spine under flexion-extension, lateral bending, and axial torsion. This paper presents the dynamics and nonlinear control of the RLS. A new approach to solve for positive and nonzero cable tensions that are also continuous in time is introduced.
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McKnight, Michael. "Stowaway City: An Immersive Audio Experience for Multiple Tracked Listeners in a Hybrid Listening Environment". Leonardo Music Journal 30 (dicembre 2020): 33–37. http://dx.doi.org/10.1162/lmj_a_01091.
Testo completoAbstract (sommario):
Stowaway City is an immersive audio experience that combines electroacoustic composition and storytelling with extended reality. The piece was designed to accommodate multiple listeners in a shared auditory virtual environment. Each listener, based on their tracked position and rotation in space, wirelessly receives an individual binaurally decoded sonic perspective via open-back headphones. The sounds and unfolding narrative are mapped to physical locations in the performance area, which are only revealed through exploration and physical movement. Spatial audio is simultaneously presented to all listeners via a spherical loudspeaker array that supplements the headphone audio, thus forming a hybrid listening environment. The work is presented as a conceptual and technical design paradigm for creative sonic application of the technology in this medium. The author outlines a set of strategies that were used to realize the composition and technical affordances of the system.
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Ariska, Melly, Hamdi Akhsan e Muhammad Muslim. "Analisis Dinamika Stroller (Kereta Bayi) dengan Metode Port-Controlled Hamiltonian System (PCHS) berbasis Komputasi Fisika". JIPFRI (Jurnal Inovasi Pendidikan Fisika dan Riset Ilmiah) 4, n. 2 (28 novembre 2020): 77–84. http://dx.doi.org/10.30599/jipfri.v4i2.682.
Testo completoAbstract (sommario):
Computational physics can be used to help solve complex dynamics equations, both translational and rotational. The purpose of this study is to obtain differences in the dynamics of mechanical systems with non-holonomic constraints in various flat and curved configuration spaces based on physics computing. In this study the reduction used is a mathematical calculation of the Port-Contolled Hamiltonian System (PCHS) equation in a mechanical system that is a Stroller, so that the equation used in determining the Stroller motion equation with and without friction that moves in the curved plane in the form of a spherical surface with various initial conditions based on maple is Poincaré's equation which is based on Routhian reduction with and without friction. The effect of friction can be clearly seen through dynamics and graphical equations on the Stroller. This method can reduce the Stroller motion equation with and without friction that moves on the ball sphere clearly in the form of a set of differential equations. The findings of this study are dynamic equations and graphs of Stroller equations with and without friction that move in the curved plane in the form of a spherical ball with varying initial conditions based on maples. This study proves physical concepts about dynamics and kinematics and analyzes Stroller dynamics using computational physics to determine the characteristics of complex and complex Stroller movements, both translational and rotational.
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Ge, Q. Jeffrey, e J. M. McCarthy. "The Algebraic Classification of the Image Curves of Spherical Four-Bar Motion". Journal of Mechanical Design 113, n. 3 (1 settembre 1991): 227–31. http://dx.doi.org/10.1115/1.2912773.
Testo completoAbstract (sommario):
A rotational displacement of the coupler of a spherical four-bar linkage can be mapped to a point with coordinates given by the Euler parameters of the rotation. The set of rotational movements available to the coupler defines a curve in this three-dimensional projective space (four homogeneous coordinates). In this paper, we determine the generalized eigenvalues and eigenvectors of the pencil of quadrics that pass through this curve and examine their properties. The result is an algebraic classification of the image curves that parallels the well-known classification of spherical four-linkages. In addition, we find that the characteristic polynomial of the system yields Grashof’s criterion for the rotatability of cranks.
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Meng, Huo. "Analysis and Evaluation on the Harmfulness of Sports Dance Based on Intelligent Computing". Wireless Communications and Mobile Computing 2022 (23 aprile 2022): 1–8. http://dx.doi.org/10.1155/2022/7371366.
Testo completoAbstract (sommario):
With the rapid development of motion analysis and editing technology, more and more animation technologies based on real human motion analysis are widely used in games, medicine, film and television, sports, and other fields. The role of this technology in the teaching system of sports dance arrangement cannot be ignored. This paper studies the application of intelligent algorithm in injury analysis of sports dance choreography and puts forward a smooth and natural motion editing method which is more in line with the characteristics of human motion. The square spherical surface intelligent algorithm is used to naturally transition the rotation posture of each frame of human joint, and the action modification of computer-aided dance choreography system is more in line with the real action of human body. Simulation results show that interframe data can be used for the same type of dance. Different types of dance arrangement can adopt the method of inserting a new framework between the two dance movements, so as to finally meet the needs of sports dance coaches and students to observe their own dance movements in an all-round way, so as to facilitate the arrangement and modification of sports dance movement design. It provides a certain reference for the application and development of virtual technology in the field of sports and greatly improves the current situation of sports dance teaching equipment. Through animation simulation technology, we can effectively avoid the injury caused by dangerous movements, provide a way of observation and improvement for coaches’ dance teaching, and effectively improve the training effect. Compared with traditional dance choreography methods, the intelligent algorithm in this study can make the animation display of sports dance more coherent and realistic and effectively solve the needs of current events observation and modification in sports dance choreography. It can produce complex movements with simple movements and help teachers arrange and teach sports dance. Avoid the accidental injury caused by the limitation of time and space in traditional teaching and realize the modernization and intelligence of physical education teaching.
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Constantin, A., e R. S. Johnson. "Large gyres as a shallow-water asymptotic solution of Euler’s equation in spherical coordinates". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, n. 2200 (aprile 2017): 20170063. http://dx.doi.org/10.1098/rspa.2017.0063.
Testo completoAbstract (sommario):
Starting from the Euler equation expressed in a rotating frame in spherical coordinates, coupled with the equation of mass conservation and the appropriate boundary conditions, a thin-layer (i.e. shallow water) asymptotic approximation is developed. The analysis is driven by a single, overarching assumption based on the smallness of one parameter: the ratio of the average depth of the oceans to the radius of the Earth. Consistent with this, the magnitude of the vertical velocity component through the layer is necessarily much smaller than the horizontal components along the layer. A choice of the size of this speed ratio is made, which corresponds, roughly, to the observational data for gyres; thus the problem is characterized by, and reduced to an analysis based on, a single small parameter. The nonlinear leading-order problem retains all the rotational contributions of the moving frame, describing motion in a thin spherical shell. There are many solutions of this system, corresponding to different vorticities, all described by a novel vorticity equation: this couples the vorticity generated by the spin of the Earth with the underlying vorticity due to the movement of the oceans. Some explicit solutions are obtained, which exhibit gyre-like flows of any size; indeed, the technique developed here allows for many different choices of the flow field and of any suitable free-surface profile. We comment briefly on the next order problem, which provides the structure through the layer. Some observations about the new vorticity equation are given, and a brief indication of how these results can be extended is offered.
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Wójcicki, Piotr, e Tomasz Zientarski. "APPLICATION OF THE LENNARD-JONES POTENTIAL IN MODELLING ROBOT MOTION". Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska 9, n. 4 (15 dicembre 2019): 14–17. http://dx.doi.org/10.35784/iapgos.45.
Testo completoAbstract (sommario):
The article proposes a method of controlling the movement of a group of robots with a model used to describe the interatomic interactions. Molecular dynamics simulations were carried out in a system consisting of a moving groups of robots and fixed obstacles. Both the obstacles and the group of robots consisted of uniform spherical objects. Interactions between the objects are described using the Lennard-Jones potential. During the simulation, an ordered group of robots was released at a constant initial velocity towards the obstacles. The objects’ mutual behaviour was modelled only by changing the value of the interaction strength of the potential. The computer simulations showed that it is possible to find the optimal value of the potential impact parameters that enable the implementation of the assumed robotic behaviour scenarios. Three possible variants of behaviour were obtained: stopping, dispersing and avoiding an obstacle by a group of robots.
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Xue, Minxing, Jin Wang e Meigui Huang. "Inulin-Modified Liposomes as a Novel Delivery System for Cinnamaldehyde". Foods 11, n. 10 (18 maggio 2022): 1467. http://dx.doi.org/10.3390/foods11101467.
Testo completoAbstract (sommario):
Cinnamaldehyde as an antioxidant was encapsulated in inulin-modified nanoliposomes in order to improve its physical and antioxidant stability. The microstructure, particle size and volume distribution of cinnamaldehyde liposomes were characterized by atomic force microscopy (AFM) and dynamic light scattering (DLS). The particle size and polydispersion index (PDI) values of the inulin modified liposomes were 72.52 ± 0.71 nm and 0.223 ± 0.031, respectively. The results showed that the liposomes after surface modification with inulin remained spherical. Raman and Fourier transform infrared (FTIR) spectra analysis showed that hydrogen bonds were formed between the inulin and the liposome membrane. Inulin binding also restricted the freedom of movement of lipid molecules and enhanced the order of the hydrophobic core of the membrane and the polar headgroup region in lipid molecules. Therefore, the addition of different concentrations of inulin influenced the permeability of the liposome bilayer membrane. However, when inulin was excessive, the capacity of the bilayer membrane to load the cinnamaldehyde was reduced, and the stability of the system was reduced. Additionally, the encapsulation efficiency (EE) and retention rate (RR) of cinnamaldehyde from inulin-modified liposomes during storage were determined. The EE value of the inulin modified liposomes was 70.71 ± 0.53%. The liposomes with 1.5% inulin concentration had the highest retention rate (RR) and the smallest particle size during storage at 4 °C. The addition of inulin also enhanced the thermal stability of the liposomes. Based on the results, the surface modification improved the oxidation stability of liposomes, especially the DPPH scavenging ability. In conclusion, these results might help to develop inulin as a potential candidate for the effective modification of the surface of liposomes and provide data and conclusions for it.
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Попиков, Петр, P. Popikov, П. Гончаров, P. Goncharov, Андрей Шаров e Andrey Sharov. "Modelling workflow forest fire soil - thrower with energy-saving hydraulic drive". Forestry Engineering Journal 7, n. 4 (30 gennaio 2018): 182–89. http://dx.doi.org/10.12737/article_5a3d097ac621c3.55675220.
Testo completoAbstract (sommario):
The article is a schematic diagram of the hydraulic soil-thrower with connection air-charged accumulator which stores energy during overload when working bodies meeting with obstacles, while avoiding the operation of safety valves and conversion hydraulic energy into heat. Mathematical model that comprehensively describes the events taking place: the rotation and movement of the rotor soil-thrower rotor interaction with the ground and obstacles, the drive ground in space. In the method of the soil and the obstacles presented a collection of a large number (about 2000 ... 10000) spherical elements of small size, enabled communicate both among themselves and with the blades soil-thrower. The simulation is performed in three-dimensional space XYZ, where in the same elements have a spherical shape with the same diameter. With in the framework of the model developed by the working surfaces are represented as a set of elementary triangles. Rotor soil-thrower model with some degree of desensitization is represented by four rectangular blades, each of which consists of two triangles. In the process of simulation reproduced rotation of the rotor and the calculation of the interaction with the elements of triangular surfaces ground and obstacles. To solve the system of differential-social and algebraic equations, which laid the basis for the model, time-operated computer program "Program for modeling the work of forest fire soil-thrower with energy saving action hydraulic drive" program time to work in Borland Delphi environment 7.0 language Object Programming PascalIzucheny soil-thrower stage of interaction with the irresistible preption. Using the powering hydraulic system improves the uniformity of rotation of the rotor, to reduce energy costs for rotorus rotation by 12%.