kinematical model
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2022 ◽  
Vol 924 (2) ◽  
pp. 86
Author(s):  
Zhijie Qu ◽  
Ryan Lindley ◽  
Joel N. Bregman

Abstract We compose a 265-sight-line Milky Way C iv line-shape sample using the Hubble Space Telescope/Cosmic Origins Spectrograph archive, which is complementary to the existing Si iv samples. C iv has a higher ionization potential (47–64 eV) than Si iv (33–45 eV), so it also traces warm gas, which is roughly cospatial with Si iv. The spatial density distribution and kinematics of C iv are identical to those Si iv within ≈2σ. C iv is more sensitive to the warm gas density distribution at large radii with a higher element abundance. Applying the kinematical model to the C iv sample, we find two possible solutions of the density distribution, which are distinguished by the relative extension along the disk midplane and the normal-line direction. Both solutions can reproduce the existing sample and suggest a warm gas disk mass of log M ( M ⊙ ) ≈ 8 and an upper limit of log M ( M ⊙ ) < 9.3 within 250 kpc, which is consistent with Si iv. There is a decrease in the C iv/Si iv column density ratio from the Galactic center to the outskirts by 0.2–0.3 dex, which may suggest a phase transition or different ionization mechanisms for C iv and Si iv. Also, we find that the difference between C iv and Si iv is an excellent tracer of small-scale features, and we find a typical size of 5°–10° for possible turbulence within individual clouds (≈1 kpc).


2021 ◽  
Vol 14 (1) ◽  
pp. 44-50
Author(s):  
Csongor Kelemen ◽  
Márton Máté

Abstract The manufacturing precision of involute worms constitutes a major requirement. On the one hand, the worm constitutes the input element of the worm drive; secondly, the involute helical surface is the basic surface of an involute worm-hob. This paper presents an analytic comparison between the involute surfaces obtained using theoretical equations, kinematic simulation of the cutting and the surface charged with errors. The surface error is considered the distance along the normal direction to the theoretical surface, measured between this and the surface charged with simulated manufacturing errors. The main sources of errors are considered the center-error of the edge plane, the edge profile error and deviation of the axial feed direction from the axis of the worm. The theoretical results allow us to conclude that the influence of the edge profile error is the largest. It is followed by the parallelism error between the feed direction and the axis of the worm, and finally, the center error of the tool edge.


Author(s):  
Bryan Ghoslin ◽  
Vidya K. Nandikolla

Abstract The paper presents a Brain-Computer Interface (BCI) controller for a semiautonomous three-wheeled omnidirectional robot capable of processing real-time commands. The kinematical model of the omni-directional robot and the software architecture of the overall hybrid system with motion control algorithm are presented. The system design, acquisition of the electroencephalography (EEG) signal, recognition processing technology and implementation are the main focus. Signals are recorded and processed by a program called OpenVibe. Preprocessed signals are cleaned by EEGLAB and used to train OpenVibe classifiers to accurately identify the expected signals produced by the users. Once identified, the controller converts the signal into input commands {forward, left, right, rotate, stop}, which are written in the Python syntax and delivered to the robot system. The robot has three degrees of freedom (DoF) allowing it to traverse its environment in any direction and orientation. The sensor system provides feedback allowing for the semi-autonomous control to avoid obstacles. Overall, this paper demonstrates the architecture of the hybrid control system for omni-directional robot using BCI. The developed system integrates the EEG signal to control the motion of the robot and the experimental results show the system performance and effectiveness of possessing the user’s EEG signals.


2020 ◽  
Vol 894 (2) ◽  
pp. 142
Author(s):  
Zhijie Qu ◽  
Joel N. Bregman ◽  
Edmund Hodges-Kluck ◽  
Jiang-Tao Li ◽  
Ryan Lindley
Keyword(s):  

Earthmoving machines like excavators and loaders characteristics such as productivity, weight, reliability depend on their backhoe mechanism. For that, the backhoe mechanism has to deliver the desired working range, digging forces and stability which are dependent on structural parameters like components length and joint angles. This paper describes the method of developing a backhoe mechanism for the desired working range which constitutes cutting heights and reaches by using structural parameters. This requires to develop forward kinematical model by considering the backhoe mechanism as a mechanical manipulator. A computer algorithm was developed, that uses the forward kinematic model, to estimate the working range. Also, a relationship is established between joint angles and cylinder lengths. Results of Virtual prototype, modeled and simulated in MSC ADAMS along with the testing results of BEML designed Physical prototype were used to validate the working range and structural parameters. This research provides a solid foundation for analyzing the effect of structural parameters on digging forces and stability.


2019 ◽  
Vol 629 ◽  
pp. A8 ◽  
Author(s):  
D. Tafoya ◽  
G. Orosz ◽  
W. H. T. Vlemmings ◽  
R. Sahai ◽  
A. F. Pérez-Sánchez

Context. Water-fountain nebulae are asymptotic giant branch (AGB) and post-AGB objects that exhibit high-velocity outflows traced by water-maser emission. Their study is important for understanding the interaction between collimated jets and the circumstellar material that leads to the formation of bipolar and/or multi-polar morphologies in evolved stars. Aims. The aim of this paper is to describe the three-dimensional morphology and kinematics of the molecular gas of the water-fountain nebula IRAS 16342−3814. Methods. Data was retrieved from the ALMA archive for analysis using a simple spatio-kinematical model. The software SHAPE was employed to construct a three-dimensional, spatio-kinematical model of the molecular gas in IRAS 16342−3814, and to then reproduce the intensity distribution and position-velocity diagram of the CO emission from the ALMA observations to derive the morphology and velocity field of the gas. Data from CO(J = 1 → 0) supported the physical interpretation of the model. Results. A spatio-kinematical model that includes a high-velocity collimated outflow embedded within material expanding at relatively lower velocity reproduces the images and position-velocity diagrams from the observations. The derived morphology is in good agreement with previous results from IR and water-maser emission observations. The high-velocity collimated outflow exhibits deceleration across its length, while the velocity of the surrounding component increases with distance. The morphology of the emitting region, the velocity field, and the mass of the gas as function of velocity are in excellent agreement with the properties predicted for a molecular outflow driven by a jet. The timescale of the molecular outflow is estimated to be ~70–100 yr. The scalar momentum carried by the outflow is much larger than it can be provided by the radiation of the central star. An oscillating pattern was found associated with the high-velocity collimated outflow. The oscillation period of the pattern is T ≈ 60–90 yr and its opening angle is θop ≈ 2°. Conclusions. The CO (J = 3 → 2) emission in IRAS 16342−3814 is interpreted in terms of a jet-driven molecular outflow expanding along an elongated region. The position-velocity diagram and the mass spectrum reveal a feature due to entrained material that is associated with the driving jet. This feature is not seen in other more evolved objects that exhibit more developed bipolar morphologies. It is likely that the jet in those objects has already disappeared since it is expected to last only for a couple hundred years. This strengthens the idea that water fountain nebulae are undergoing a very short transition during which they develop the collimated outflows that shape the circumstellar envelopes. The oscillating pattern seen in the CO high-velocity outflow is interpreted as due to precession with a relatively small opening angle. The precession period is compatible with the period of the corkscrew pattern seen at IR wavelengths. We propose that the high-velocity molecular outflow traces the underlying primary jet that produces such a pattern.


2019 ◽  
Vol 623 ◽  
pp. A96 ◽  
Author(s):  
Hsi-Wei Yen ◽  
Shigehisa Takakuwa ◽  
Pin-Gao Gu ◽  
Naomi Hirano ◽  
Chin-Fei Lee ◽  
...  

Aims. HL Tau is a Class I–II protostar embedded in an infalling and rotating envelope and possibly associated with a planet forming disk, and it is co-located in a 0.1 pc molecular cloud with two nearby young stellar objects with projected distance of ~20′′–30′′ (2800–4200 au) to HL Tau. Our observations with the Atacama Large Millimeter/Submillimeter Array (ALMA) revealed two arc-like structures on a 1000 au scale connected to the disk, and their kinematics could not be explained with any conventional model of infalling and rotational motions. In this work, we investigate the nature of these arc-like structures connected to the HL Tau disk. Methods. We carried out new observations in the 13CO and C18O (3–2; 2–1) lines with the James Clerk Maxwell Telescope and the IRAM 30m telescope, and obtained the data with the 7-m array of the Atacama Compact Array (ACA). With the single-dish, ACA, and ALMA data, we analyzed the gas motions on both 0.1 pc and 1000 au scales in the HL Tau region. We constructed new kinematical models of an infalling and rotating envelope with the consideration of relative motion between HL Tau and the envelope. Results. By including the relative motion between HL Tau and its protostellar envelope, our kinematical model can explain the observed velocity features in the arc-like structures. The morphologies of the arc-like structures can also be explained with an asymmetric initial density distribution in our model envelope. In addition, our single-dish results support the scenario that HL Tau is located at the edge of a largescale (0.1 pc) expanding shell driven by the wind or outflow from XZ Tau, as suggested in the literature. The estimated expanding velocity of the shell is comparable to the relative velocity between HL Tau and its envelope in our kinematical model. These results hint that the largescale expanding motion likely impacts the protostellar envelope around HL Tau and affects its gas kinematics. We found that the mass infalling rate from the envelope onto the HL Tau disk can be decreased by a factor of two due to this impact by the largescale expanding shell.


2018 ◽  
Vol 7 ◽  
pp. 450-452
Author(s):  
Boris Boyarshinov ◽  
◽  
Nina Yuzhakova
Keyword(s):  

Author(s):  
Al. V. Tevelev ◽  
I. A. Prudnikov ◽  
Ark. V. Tevelev ◽  
A. O. Khotylev ◽  
E. A. Volodina

In this work we reported the structural features and mechanism of the formation of the Simskaya low of the Uralian foreland basin, besides the Karatau-Suleyman block as a whole. This block has the shape of a wedge, so with a general latitudinal compression, it experienced lateral extrusion to the north along the conjugated shear zones. This factor determined the local situation of meridional compression and latitudinal tension. In the central part of the block, the latitudinal stretching was compensated for by gradual deflection, which led to the formation of the Simskaya low.


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