Anisotropic inverse Compton emission in the radio galaxy 3C 265

We present the results from a Chandra observation of the powerful radio galaxy 3C 265. We detect X-ray emission from the nucleus, the radio hotspots and lobes. In particular, the lobe X-ray emission is well explained as anisotropic inverse Compton scattering of the nuclear photons by the relativistic electrons in the radio lobes; the comparison between radio synchrotron and IC emission yields a magnetic field strength a factor about 2 lower than that calculated under minimum energy conditions. The X-ray spectrum of the nucleus is consistent with that of a powerful, strongly absorbed quasar and the X-ray emission of the south-eastern hotspot can be successfully reproduced by a combination of synchro-self Compton and inverse Compton emission assuming a magnetic field slightly lower than equipartition.Comment: 5 pages, 6 figures, to be published as a Letter on Monthly Notices of the Royal Astronomical Societ

An artificially generated atmosphere near a lunar base

We discuss the formation of an artificial atmosphere generated by vigorous lunar base activity in this paper. We developed an analytical, steady-state model for a lunar atmosphere based upon previous investigations of the Moon's atmosphere from Apollo. Constant gas-injection rates, ballistic trajectories, and a Maxwellian particle distribution for an oxygen-like gas are assumed. Even for the extreme case of continuous He-3 mining of the lunar regolith, we find that the lunar atmosphere would not significantly degrade astronomical observations beyond about 10 km from the mining operation

Are 3C249.1 and 3C334 restarted quasars?

This Research Note follows up a Letter in which I posit that J1211+743 is a restarted radio source. This means that its structure, where the jet points to the relic lobe, is only apparently paradoxical. Here, I propose the same scenario and apply the same mathematical model to 3C249.1 and 3C334. The ultimate result of my investigation is that these two well-known radio-loud quasars can be understood best so far if it was assumed that they, too, had been restarted.Comment: 4 pages, accepted for publication in A&A as a Research Not

The Cygnus X region XXIII. Is 18P87 galactic or extragalactic?

The radio source 18P87, previously thought to be a point source, has been serendipitously found to be resolved into a core-jet geometry in VLA maps. HI absorption of continuum emission (in data from the Canadian Galactic Plane Survey) appears in gas with radial velocities > +2 km/s but not in brightly emitting gas at lower radial velocity. Examination of further archival observations at radio, infrared and optical wavelengths suggests that the "obvious" interpretation as a radio galaxy requires a rather unusual object of this kind and a highly unusual local line of sight. We argue that 18P87 may be a Galactic object, a local astrophysical jet. If this is correct it could have arisen from outbursts of a microquasar.Comment: Accepted for publication in Astronomische Nachrichte

Kinematic Modeling and Simulation of a 2-R Robot by Using Solid Works and Verification by MATLAB/Simulink

Simulation of robot systems which is getting very popular, especially with the lowering cost of computers, can be used for layout evaluation, feasibility studies, presentations with animation and off-line programming. Object staging modelisation using robots holds, wether for the object or the robot, the following models: The geometric one, the kinematics one and the dynamic one. To do so, the modelisation of a 2-R robot type is being implemented. Comparing between two robot postures with the same trajectory (path) and for the same length of time and establishing a computing code to obtain the kinematic and dynamic parameters are the main tasks. SolidWorks and Matlab/Simulink softwares are used to check the theory and the robot motion simulation. The verification of the obtained results by both softwares allows us to, qualitatively evaluate ,underline the rightness of the chosen model and to get the right conclusions. The results of simulations were discussed. An agreement between the two softwares is certainly Obtained.DOI: http://dx.doi.org/10.11591/ijra.v1i2.35

Dynamic Behavior of a SCARA Robot by using N-E Method for a Straight Line and Simulation of Motion by using Solidworks and Verification by Matlab/Simulink

SCARA (Selective Compliant Assembly Robot Arm) robot of serial architecture is widely used in assembly operations and operations "pick-place", it has been shown that use of robots improves the accuracy of assembly, and saves assembly time and cost as well. The most important condition for the choice of this kind of robot is the dynamic behavior for a given path, no closed solution for the dynamics of this important robot has been reported. This paper presents the study of the kinematics (forward and inverse) by using D-H notation and the dynamics of SCARA robot by using N-E methods. A computer code is developed for trajectory generation by using inverse kinematics, and calculates the variations of the torques of the links for a straight line (path rest to rest) between two positions for operation "pick-place". SCARA robot is constructed to achieve “pick-place» operation using SolidWorks software. And verification by Matlab/Simulink. The results of simulations were discussed. An agreement between the two softwares is certainly obtained herei

Robot Kinematics, using Dual Quaternions

From the point of view of classical mechanics, deriving the equations of motion for systems of coupled rigid bodies is regarded as a straightforward procedure: once a suitable set of generalized coordinates and reference frames have been chosen, what remains is to either apply Lagrange’s equations or Newton and Euler’s equations to obtain the differential equations of motion. As the complexity of multibody system increases, the need for more elegant formulation of the equation of motion becomes an issue of paramount importance. Our primary focus is on the kinematic analysis of rigid bodies and serial manipulators (robotic systems)  using simultaneously, both homogeneous transformations (4x4) matrices and Dual Quaternions, for the sake of results comparisons (cost,complexity,storage capacity etc.) . This paper has been done mainly for educational and peadagogical purposes, hoping that the scientific community will finally adopt and use Dual Quaternions at least when dealing with multibody systems and specially robotics.DOI: http://dx.doi.org/10.11591/ijra.v1i1.27

The dust-eliminated shape of quasar spectra in the near-infrared: a hidden part of the big blue bump

The near-infrared shape of the big blue bump component in quasar spectra has been essentially unknown. It usually cannot be observed directly, due to the strong hot dust emission which dominates quasar spectra longward of ~1micron. However this is quite an important part of the spectrum theoretically. At least bare disk models provide quite a robust prediction for the overall continuum shape in the near-infrared. Self-gravity should become important in the outer, near-infrared emitting regions of the putative disk, possibly leaving a signature of disk truncation in the near-infrared. We propose here that this important part of the spectrum can be revealed for the first time by observing polarized flux from normal quasars. At least in some polarized quasars, the emission lines are all unpolarized and so the polarized flux should originate interior to the broad line region, and therefore also interior to the dust emitting region. This can then be used to eliminate the dust emission. We present the results of near-infrared polarimetry for such three quasars (Ton202, 4C37.43, B2 1208+32). The data for Ton202 have the highest S/N, and the near-infrared polarized flux in this case is measured to have quite a blue shape, nu^+0.42+-0.29 in F_nu, intriguingly consistent with the simple multi-temperature black body, bare disk prediction of nu^+1/3. All these data, although still with quite low S/N for the other two objects, demonstrate the unique potential of the technique with future better data. We also present similar data for other quasars and radio galaxies, and briefly discuss the nature of the polarization.Comment: MNRAS in pres

Martian Ionosphere Electron Density Prediction Using Bagged Trees

The availability of Martian atmospheric data provided by several Martian missions broadened the opportunity to investigate and study the conditions of the Martian ionosphere. As such, ionospheric models play a crucial part in improving our understanding of ionospheric behavior in response to different spatial, temporal, and space weather conditions. This work represents an initial attempt to construct an electron density prediction model of the Martian ionosphere using machine learning. The model targets the ionosphere at solar zenith ranging from 70 to 90 degrees, and as such only utilizes observations from the Mars Global Surveyor mission. The performance of different machine learning methods was compared in terms of root mean square error, coefficient of determination, and mean absolute error. The bagged regression trees method performed best out of all the evaluated methods. Furthermore, the optimized bagged regression trees model outperformed other Martian ionosphere models from the literature (MIRI and NeMars) in finding the peak electron density value, and the peak density height in terms of root-mean-square error and mean absolute error.Comment: The peer-reviewed paper is available at: https://doi.org/10.1109/ICECTA57148.2022.999050

Multi-instrument analysis of L-band amplitude scintillation observed over the Eastern Arabian Peninsula

This study investigates the spatial and temporal characteristics of L1 amplitude scintillation-causing ionospheric irregularities over the Eastern Arabian Peninsula during the ascending phase of solar cycle 25 (years 2020--2023). The temporal occurrences of weak and strong scintillation were separated by sunset, with weak scintillation observed predominantly pre-sunset during the winter solstice and strong scintillation observed mainly post-sunset during the autumnal equinox. Strong scintillation was much more pronounced in 2023 compared to the other three years, indicating a strong influence of solar activity. Spatially, weak-scintillation-causing irregularities exhibited a wide distribution in azimuth and elevation, while strong-scintillation-causing irregularities were concentrated southwards. The combined analysis of S4 and rate of total electron content index (ROTI) suggested that small-scale ionospheric irregularities were present in both pre- and post-sunset periods, while large-scale irregularities were only seen during the post-sunset period. Furthermore, the presence of southward traveling ionospheric disturbances (TIDs) during the 2023 autumnal equinox was confirmed with the total electron content anomaly ($\Delta\text{TEC}$), while the Ionospheric Bubble Index (IBI) provided by the Swarm mission was unable to confirm the presence of equatorial plasma bubbles during the same period. Observations from the FORMOSAT-7/COSMIC-2 mission indicated that strong-scintillation-causing irregularities were more prevalent under the F2-layer peak, while the weak-scintillation-causing irregularities were mostly observed at the E-layer, F2-layer, and above the F2-layer