angular velocity
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Author(s):  
Gabriel G. Zimmermann ◽  
Samir P. Jasper ◽  
Daniel Savi ◽  
Leonardo L. Kmiecik ◽  
Lauro Strapasson Neto ◽  
...  

ABSTRACT The establishment of grain crops in Brazil is an important industrial process in the agricultural chain, requiring the correct deposition of granular fertilizer over the sowing furrow and more efficient, precise, and sustainable assessments in the operation, which can be achieved with the statistical process control. This study aimed to assess the effect of the angular velocity on different inclinations of the helical metering mechanism on the granular fertilizer deposition. An automated electronic bench was used to assess the deposition quality of granular fertilizers considering different angular velocities (1.11, 1.94, and 2.77 m s-1) and longitudinal and transverse inclinations (+15, +7.5, 0, −7.5, and −15°), with the helical doser by overflow. Flow data were collected and submitted to descriptive statistics and statistical process control. The metering mechanism showed expected variations, with acceptable performance under process control. The values of the flow rates of the granular fertilizer increased as velocity increased, standing out longitudinal inclinations of +7.5 and +15°, providing higher fertilizer depositions.


2022 ◽  
Author(s):  
Ryunosuke Harada ◽  
Hiroshi Yoshitake ◽  
Motoki Shino

Abstract To ensure the coexistence of autonomous personal mobility vehicles (PMVs) and pedestrians in a pedestrian zone, they should be able to smoothly pass across and avoid each other. Studies suggest that it is possible that PMVs and pedestrians can pass each other in a short period of time without compromising their comfort; this can be achieved through understanding how pedestrians react to the behavior of PMVs and by modifying the autonomous navigation of PMVs accordingly. Therefore, in this study, the avoidance behavior characteristics of pedestrians were investigated. Experiments were conducted to understand the influence of the selected avoiding behavior parameters and to understand the behavior characteristics of pedestrians in relation to the behavior of PMVs. Furthermore, a path planning strategy that enables smooth passing was developed based on these characteristics. The usefulness of this method was evaluated. The avoidance time and the avoiding angular velocity at the start and end of the avoidance behavior were the parameters that contributed to smooth autonomous navigation. The results show that pedestrian tolerance improves and the avoidance width decreases depending on these parameters. Furthermore, smooth autonomous navigation can be achieved using the characteristics of pedestrians’ cognition against PMVs.


Aerospace ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 33
Author(s):  
Minghe Shan ◽  
Lingling Shi

The space debris problem poses a huge threat to operational satellites and has to be addressed. Multiple removal methods have been proposed to keep Earth’s orbit stable. Flexible connection capturing methods, such as the harpoon system, tether–gripper system and the net system, are potential candidate methods for space debris removal in the future. However, the tethered system is usually assumed as a dumbbell model where two end masses are connected by a rigid bar. This traditional model is not accurate enough to predict the motion of the target, neither the whole system. In this paper, three models, namely the modified dumbbell model, lumped-mass model and the ANCF model, to describe a tethered post-capture system for space debris removal are described and compared. Moreover, modal analysis of the tethered system is performed, and an analytical solution of the system’s natural frequency is derived. In addition, two configurations of the tethered system, namely the single tether configuration and the sub-tether configuration are simulated and compared based on three models, respectively. Finally, the influence on the chaser satellite by the initial angular velocity of the target is analyzed.


Robotics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 11
Author(s):  
Daniele Costa ◽  
Cecilia Scoccia ◽  
Matteo Palpacelli ◽  
Massimo Callegari ◽  
David Scaradozzi

Bio-inspired solutions devised for Autonomous Underwater Robots are currently investigated by researchers as a source of propulsive improvement. To address this ambitious objective, the authors have designed a carangiform swimming robot, which represents a compromise in terms of efficiency and maximum velocity. The requirements of stabilizing a course and performing turns were not met in their previous works. Therefore, the aim of this paper is to improve the vehicle maneuvering capabilities by means of a novel transmission system capable of transforming the constant angular velocity of a single rotary actuator into the pitching–yawing rotation of fish pectoral fins. Here, the biomimetic thrusters exploit the drag-based momentum transfer mechanism of labriform swimmers to generate the necessary steering torque. Aside from inertia and encumbrance reduction, the main improvement of this solution is the inherent synchronization of the system granted by the mechanism’s kinematics. The system was sized by using the experimental results collected by biologists and then integrated in a multiphysics simulation environment to predict the resulting maneuvering performance.


2022 ◽  
Vol 3 (1) ◽  
pp. 78-87
Author(s):  
Reza Shirsavar ◽  
Saeid Mollaei ◽  
Mansoure Moeini Rizi ◽  
Ali-Reza Moradi ◽  
Ahmad Amjadi ◽  
...  

Applying a constant electric field on a suspended film of liquid that carries an electric current, either by the transport of ions or surface charges, induces a rotation in the film. This system is known as “liquid film motor”. So far, the effect of permittivity of the liquid on its rotation has been ignored. We showed that the permittivity of the liquid can significantly affect the dynamics of rotation. Using an experimental approach, we studied the liquid film rotation for a broad range of pure liquids with diverse permittivities and surface tensions. We observed two different regimes of rotation depending on the permittivity of the liquids. We also found that there is no correlation between the surface tension of the liquid and the angular velocity of the rotation. We considered a theoretical framework and suggested scenarios to explain our experimental observations. These results help in better understanding the physics of liquid film motors and suggest opportunities for new flow manipulation techniques at small scales.


2022 ◽  
Vol 13 ◽  
pp. 54-62
Author(s):  
Huang-Hsiang Lin ◽  
Jonathan Heinze ◽  
Alexander Croy ◽  
Rafael Gutiérrez ◽  
Gianaurelio Cuniberti

Lubricants are widely used in macroscopic mechanical systems to reduce friction and wear. However, on the microscopic scale, it is not clear to what extent lubricants are beneficial. Therefore, in this study, we consider two diamond solid-state gears at the nanoscale immersed in different lubricant molecules and perform classical MD simulations to investigate the rotational transmission of motion. We find that lubricants can help to synchronize the rotational transmission between gears regardless of the molecular species and the center-of-mass distance. Moreover, the influence of the angular velocity of the driving gear is investigated and shown to be related to the bond formation process between gears.


Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 385
Author(s):  
Masoud Abdollahi ◽  
Pranav Madhav Kuber ◽  
Michael Shiraishi ◽  
Rahul Soangra ◽  
Ehsan Rashedi

Background: A stroke often bequeaths surviving patients with impaired neuromusculoskeletal systems subjecting them to increased risk of injury (e.g., due to falls) even during activities of daily living. The risk of injuries to such individuals can be related to alterations in their movement. Using inertial sensors to record the digital biomarkers during turning could reveal the relevant turning alterations. Objectives: In this study, movement alterations in stroke survivors (SS) were studied and compared to healthy individuals (HI) in the entire turning task due to its requirement of synergistic application of multiple bodily systems. Methods: The motion of 28 participants (14 SS, 14 HI) during turning was captured using a set of four Inertial Measurement Units, placed on their sternum, sacrum, and both shanks. The motion signals were segmented using the temporal and spatial segmentation of the data from the leading and trailing shanks. Several kinematic parameters, including the range of motion and angular velocity of the four body segments, turning time, the number of cycles involved in the turning task, and portion of the stance phase while turning, were extracted for each participant. Results: The results of temporal processing of the data and comparison between the SS and HI showed that SS had more cycles involved in turning, turn duration, stance phase, range of motion in flexion–extension, and lateral bending for sternum and sacrum (p-value < 0.035). However, HI exhibited larger angular velocity in flexion–extension for all four segments. The results of the spatial processing, in agreement with the prior method, showed no difference between the range of motion in flexion–extension of both shanks (p-value > 0.08). However, it revealed that the angular velocity of the shanks of leading and trailing legs in the direction of turn was more extensive in the HI (p-value < 0.01). Conclusions: The changes in upper/lower body segments of SS could be adequately identified and quantified by IMU sensors. The identified kinematic changes in SS, such as the lower flexion–extension angular velocity of the four body segments and larger lateral bending range of motion in sternum and sacrum compared to HI in turning, could be due to the lack of proper core stability and effect of turning on vestibular system of the participants. This research could facilitate the development of a targeted and efficient rehabilitation program focusing on the affected aspects of turning movement for the stroke community.


Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 28
Author(s):  
Yuanyuan Duan ◽  
Fangxun Liu ◽  
Yu Wang ◽  
Yen Chin Ong

While it is tempting to think of closed time-like curves (CTCs) around rotating bodies, such as a black hole, as being “caused” by the rotation of the source, Andréka et al. pointed out that the underlying physics are not as straightforward as this, since such CTCs are “counter-rotating”, i.e., the time orientation (the opening of the local light cones) of the CTCs is opposite to the direction in which the singularity or the ergosphere rotates. It was also suggested that this is a generic phenomenon that calls for a deeper intuitive physical understanding. In this short note, we point out—with Kerr–Taub–NUT as an example—that CTCs are counter-rotating with respect to the local angular velocity of the spacetime, not the global angular momentum, nor the angular velocity of the black hole horizon, which makes the physical interpretation of CTCs being “caused” by a rotating source even more problematic.


2022 ◽  
Author(s):  
Ma Ruyu ◽  
Haoyang Yu ◽  
MA QIUYING ◽  
ZHOU QIAN ◽  
Kai Ni

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