Kinematic Structure Research Articles

ՈՒՂՂԱՁԻԳ ՎԵՐԹԻՌՈՎ ԵՎ ՎԱՅՐԷՋՔՈՎ ԱԹՍ-Ի ԿԻՆԵՄԱՏԻԿ ՎԵՐԼՈՒԾՈՒԹՅՈՒՆԸ ԵՎ ԿԱՌԱՎԱՐՄԱՆ ՀԱՄԱԿԱՐԳԻ ՆԱԽԱԳԾՈՒՄԸ MATLAB SIMULINK ՄԻՋԱՎԱՅՐՈՒՄ / KINEMATICS ANALYSIS AND CONTROL SYSTEM DESIGN OF VERTICAL TAKE-OFF AND LANDING UAV IN MATLAB SIMULINK ENVIRONMENT

The kinematic structure was designed for a new type of pitch-decoupled vertical take-off and landing UAV (VTOL UAV), based on which the equations and matrix describing its kinematics were derived. The kinematics equations were derived based on Denavit-Hartenberg’s method for robot manipulators, considering the VTOL UAV as a robotic system and its connections as kinematic connection links of the robot. A reference frame was assigned to each of the separate links, from which the transition to the coordinate system of the next link was described by a homogeneous transformation matrix. For each link, its position with respect to its own reference frame was calculated. Based on that, the kinematics matrix was derived, which allows for calculating the required torques of the UAV. In the MATLAB SIMULINK environment, an UAV control system was designed that is based on the kinematic matrix and linear, rotational motion dynamics equations. To check the system’s operability, a proportional, Integral-Derivative (PID) regulator with pre-selected coefficients was selected as a regulator. System research was carried out with pitch, roll, yaw, and decoupled pitch axes as well as height axis.

Singularity Avoidance with Application to Online Trajectory Optimization for Serial Manipulators

This work proposes a novel singularity avoidance approach for real-time trajectory optimization based on known singular configurations. The focus of this work lies on analyzing kinematically singular configurations for three robots with different kinematic structures, i.e., the Comau Racer 7-1.4, the KUKA LBR iiwa 14 R820, and the Franka Emika Panda, and exploiting these configurations in form of tailored potential functions for singularity avoidance. Monte Carlo simulations of the proposed method and the commonly used manipulability maximization approach are performed for comparison. The numerical results show that the average computing time can be reduced and shorter trajectories in both time and path length are obtained with the proposed approach.

The Mean Kinematic Structure of the Tropical Cyclone Boundary Layer and Its Relationship to Intensity Change

Abstract This study investigates the relationship between the azimuthally averaged kinematic structure of the tropical cyclone boundary layer (TCBL) and storm intensity, intensity change, and vortex structure above the BL. These relationships are explored using composites of airborne Doppler radar vertical profiles, which have a higher vertical resolution than typically used three-dimensional analyses and, therefore, better capture TCBL structure. Results show that the BL height, defined by the depth of the inflow layer, is greater in weak storms than in strong storms. The inflow layer outside the radius of maximum tangential wind speed (RMW) is deeper in intensifying storms than in nonintensifying storms at an early stage. The peak BL convergence inside the RMW is larger in intensifying storms than in nonintensifying storms. Updrafts originating from the TCBL are concentrated near the RMW for intensifying TCs, while updrafts span a large radial range outside the RMW for nonintensifying TCs. In terms of vortex structure above the BL, storms with a quickly decaying radial profile of tangential wind outside the RMW (“narrow” vortices) tend to have a deeper inflow layer outside the RMW, stronger inflow near the RMW, deeper and more concentrated strong updrafts close to the RMW, and weaker inflow in the outer core region than those with a slowly decaying tangential wind profile (“broad” vortices). The narrow TCs also tend to intensify faster than broad TCs, suggesting that a key relationship exists among vortex shape, the BL kinematic structure, and TC intensity change. This relationship is further explored by comparisons of absolute angular momentum budget terms for each vortex shape.

Salt-bearing Disk Candidates around High-mass Young Stellar Objects

Molecular lines tracing the orbital motion of gas in a well-defined disk are valuable tools for inferring both the properties of the disk and the star it surrounds. Lines that arise only from a disk, and not also from the surrounding molecular cloud core that birthed the star or from the outflow it drives, are rare. Several such emission lines have recently been discovered in one example case, those from NaCl and KCl salt molecules. We studied a sample of 23 candidate high-mass young stellar objects (HMYSOs) in 17 high-mass star-forming regions to determine how frequently emission from these species is detected. We present five new detections of water, NaCl, KCl, PN, and SiS from the innermost regions around the objects, bringing the total number of known briny disk candidates to nine. Their kinematic structure is generally disk-like, though we are unable to determine whether they arise from a disk or outflow in the sources with new detections. We demonstrate that these species are spatially coincident in a few resolved cases and show that they are generally detected together, suggesting a common origin or excitation mechanism. We also show that several disks around HMYSOs clearly do not exhibit emission in these species. Salty disks are therefore neither particularly rare in high-mass disks, nor are they ubiquitous.

Complete factor experiments on fifth-class rotary kinematic couples

The article presents the analysis of the results of the multi-factor experiment conducted on the experimental tests conducted on the improved fifth-class rotary kinematic pair available in technological machines. Recommendations for the number of longitudinal grooves opened in the inner cylinder of the fifth-class rotary kinematic pair structure, their angle of inclination relative to the axis, and the use of lubricating oil are given. Test results and conclusions are presented.

Comprehensive Review of Different Pendulum Structures in Engineering Applications

For years, the pendulum system has been the most popular experimental setup for education and research in robotics and control theory. This paper examines the different kinematic and dynamic structures of pendulum systems, which are frequently used in literature, considering their usage in various engineering fields. Each pendulum system resembles a real physical system, allowing for a deeper understanding of the system’s behavior. While each pendulum has its own advantages and disadvantages, they are subjective and depend on the field of application and method of use. This paper aims to review and simplify the understanding of the various pendulum systems used in research and applications, presenting a summary of the general properties of pendulum systems to the researcher.

Evaluating the critical velocity of air entrainment by plunging water jets

It has been found that air entrainment occurs when the average jet velocity at the plunging point reaches a certain value. This velocity is called the critical velocity of air entrainment. The analysis of studies in this field shows that the process of jet interaction with the liquid surface is complex, while the theoretical approaches to its description are insufficient. The conditions at which air entrainment begins are related to the behavior and shape of the meniscus. The mechanism of meniscus formation is based on the complicated kinematic structure of motion in the vicinity of the point of interaction between the jet and the liquid in the quiescent state. Experiments and observations show that the meniscus behavior is closely related to the initial conditions of air entrainment. Calculating the critical velocity of air entrainment Ue, analysis of the meniscus shape, and use of the limit equilibrium condition were used to derive a new criterion relationship for the air entrainment conditions of turbulent jets flowing from long smooth nozzles. The results of calculations are compared with experimental data.

Trends in the implementation of non-assured structural mechanisms in technological machines modules

The results of the analysis of scientific research in the field of non-assure mechanisms are presented, on the basis of which the conclusion is made about the need for further development of the theory of mechanism structures and methodological approaches to the synthesis of machines with special properties of kinematic structure, allowing to reduce energy consumption and improve technical performance. The results of experimental studies have confirmed the existence of a relationship between the magnitude of the pre-voltage of the closed kinematic circuit and the energy intensity of the grinding and pressing process. The revealed patterns make it possible to minimize energy consumption and adapt the technological machine to the properties of the processed material. Experimental studies of a gear-grinding mill on sandstone, quartz, marble samples have confirmed that with the same energy consumption, the maximum grinding efficiency (an increase in the proportion of fine particles) is achieved only in a certain loading range of a closed kinematic contour corresponding to the strength of the crushed material.

Circumferential velocities in laminar and turbulent counter-vortex flow

Knowledge of the parameters of fluid movement is essential in the designing and operating various technological processes in various technical applications. These processes play a special role in hydro engineering, where the structures of water works are directly subjected to static and dynamic forces from the side of the water flow. The operation of hydraulic turbines, spillway and water transport systems, and other hydraulic structures is directly connected with understanding the behavior of a fluid in various regimes of movement. This report is devoted to the study of a special type of fluid and gas flow, which is called counter-vortex flow. The report compares the results of the distribution of circumferential velocities with a laminar and turbulent pattern of fluid movement. The results of the laminar flow regime were obtained using a mathematical model, and the turbulent regime on a physical model using laser technologies. Such a comparison allows one to assess two approaches in determining the kinematic structures of a complicated flow. The parameters for the viscous fluid laminar flow were determined based on the traditional system of Navier-Stokes equations by determining the dependence of the circumferential component of the total velocity at the given initial circulations and angular flow velocity. A physical model was made and equipped with a set of measuring equipment to obtain the distribution of velocities in the turbulent flow. The comparison showed that the distributions of velocities for the considered flow regimes depending on the channel radius have close coincidence. In contrast, the transformation length-wise of the active zone of the flow is significant.

Surface roughness of hardened steel 90MnCrV8 after turning with actively driven tool rotation

With the increase in the use of difficult to machine and hard materials, it is necessary to find new productive ways of machining these materials. Among these technologies, we can also include forced tool rotation turning (ADRT), the easy deployment of which is made possible by the development of CNC machine tools. This non-standard kinematic structure of machining brings many advantages, mainly in increased tool life and lower temperatures in the cutting zone. This technology can be used for the production of parts in the automotive and aerospace industries. In the experiment of the paper, the dependence of surface roughness on cutting speed in turning with forced tool rotation was investigated. A monolithic tool was designed and used for the experiments, which was predicted to have higher strength and reduced recess formation compared to a tool with an interchangeable cutting insert. The measured roughness of the machined materials reached relatively low values, which could be further improved with improvements in the overall process technology system.

Investigating Δ and Ω Baryons as Meson–Baryon Bound States in Lattice Quantum Chromodynamics

We investigate Δ and Ω baryons as meson–baryon bound states in lattice quantum chromodynamics and show that their difference results from the kinematic structure of the two meson–baryon systems, and not their interaction.

Internal Precipitation and Kinematic Structure of the South Pacific Convergence Zone

Internal Precipitation and Kinematic Structure of the South Pacific Convergence Zone

Star formation in IC1396: Kinematics and subcluster structure revealed by Gaia

Aims. We investigate the star formation history of the IC1396 region by studying its kinematics and completing the population census. Methods. We used multiwavelength data, combining optical spectroscopy to identify and classify new members and near-infrared photometry to trace shocks, jets, and outflows as well as the interactions between the cluster members and the cloud. We also used Gaia EDR3 data to identify new potential members in the multidimensional proper motion and parallax space. Results. The revised Gaia EDR3 distance is 925±73 pc, slightly closer than previously obtained with DR2. The Gaia data reveal four distinct subclusters in the region. These subclusters are consistent in distance but display differences in proper motion. This result, with their age differences, hints toward a complex and varied star formation history. The Gaia data also unveil intermediate-mass objects that tend to evade spectroscopic and disk surveys. Our analysis has allowed us to identify 334 new members. We estimate an average age of ∼4 Myr, confirming previous age estimates. With the new members added to our study, we estimate a disk fraction of 28%, lower than previous values, due to our method detecting mainly new, diskless, intermediate-mass stars. We find age differences between the subclusters, which offers evidence of a complex star formation history with different episodes of star formation.

Cold mode gas accretion on two galaxy groups at z ∼ 2

ABSTRACT We present Keck Cosmic Web Imager (KCWI) integral field spectroscopy (IFS) observations of rest-frame UV emission lines $\rm Ly\alpha$, CIVλλ 1548 Å, 1550Å, and $\rm HeII$ 1640 Å observed in the circumgalactic medium (CGM) of two z = 2 radio-loud quasar host galaxies. We detect extended emission on 80–90 kpc scale in $\rm Ly\alpha$ in both systems with CIV and $\rm HeII$ emission also detected out to 30–50 kpc. All emission lines show kinematics with a blue and redshifted gradient pattern consistent with velocities seen in massive dark matter haloes and similar to kinematic patterns of inflowing gas seen in hydrodynamical simulations. Using the kinematics of both resolved $\rm Ly\alpha$ emission and absorption, we can confirm that both kinematic structures are associated with accretion. Combining the KCWI data with molecular gas observations with Atacama Large Millimeter/submillimeter Array (ALMA) and high-spatial resolution of ionized gas with Keck OSIRIS, we find that both quasar host galaxies reside in proto-group environments at z = 2. We estimate 1–6 × 1010M⊙ of warm-ionized gas within 30–50 kpc from the quasar that is likely accreting on to the galaxy group. We estimate inflow rates of 60–200 M⊙ yr−1, within an order of magnitude of the outflow rates in these systems. In the 4C 09.17 system, we detect narrow gas streams associated with satellite galaxies, potentially reminiscent of ram-pressure stripping seen in local galaxy groups and clusters. We find that the quasar host galaxies reside in dynamically complex environments, with ongoing mergers, gas accretion, ISM stripping, and outflows likely playing an important role in shaping the assembly and evolution of massive galaxies at cosmic noon.

Input coupling modeling method for a three-PRR flexure-based compliant stage

This paper presents the input coupling modeling method for a three-PRR flexure-based compliant stage. The input coupling modeling for planar compliant mechanisms is first established. The kinematic structure of a three-PRR compliant stage is then designed, and its input coupling is derived by using the proposed method. Subsequently, the validation and analysis are carried out by using finite element method (FEM). The relationships between two main parameters and the input coupling rate of the three-PRR compliant stage are discussed, and the decoupling region is then determined. Finally, its geometrical parameters are optimized, and the workspace calculated by the analytical method is compared with that obtained from FEM. It not only provides a new input coupling modeling method for flexure-based compliant mechanisms, but also provides a reference for the design of three-PRR mechanisms.

가공용 위치 보상 2축 스테이지 최적설계

Recent, manufacturing industry has demand that a robot milling system with higher DOF than CNC milling due to an increase in demand for processing complex and flexible shapes. However, a disadvantage of low surface quality exists owing to vibrations caused by the low rigidity of the robot. The main reason for the low surface quality of a target workpiece is the resonant frequency of the robot occurring below 200 Hz . To overcome this problem, we developed a 2-DOF position compensation stage that has high dynamics. In this study, the stage of parallel kinematics using an L-shaped flexible hinge was presented and optimized for rigidity higher than that of the serial kinematics structure. The optimally designed stage through the crab-leg structure was designed with high stiffness with a moving range of 26.1 μm and natural frequency of 513.54 Hz.

Thermodynamic and kinematic structure of tropical cyclones in the western North Pacific based on ACARS/AMDAR

Meteorological variables are often reported by commercial aircraft flying around tropical cyclones (TCs). They are archived in Aircraft Communications, Addressing, and Reporting System/Aircraft Meteorological Data Relay (ACARS/AMDAR). Therefore, they are potentially useful for constructing a composite mean structure of TCs based on in-situ measurements. The number of temperature and wind observations are 4.0 × 106 and 1.0 × 104 within the radius of 1,200 km and 100 km from the TC center during 2010–2020, respectively. The warm-core potential temperature anomaly with respect to the climatology is 6.4 K, 9.1 K, and 14.4 K maximized around 300 hPa for weak, moderate, and strong TCs, respectively. The composite of the potential temperature anomaly potentially extends more than 1,000 km from the TC center in the upper troposphere, cautioning the typical definition of the environment. The region of significant upper-level positive potential temperature anomalies extends broadly with increasing TC intensity. Moreover, large TCs tend to have a broad and deep upper-level warm core for a given intensity. In addition, we ensured that a single observation of potential temperature around 300 hPa could be used as a proxy for minimum sea level pressure. Low-level inflow and upper-level outflow were detected in the ACARS/AMDAR data.

A Localized Kinematic Structure Detected in Atomic Carbon Emission Spatially Coincident with a Proposed Protoplanet in the HD 163296 Disk

Over the past 5 yr, studies of the kinematics in protoplanetary disks have led to the discovery of new protoplanet candidates and several structures linked to possible planet−disk interactions. We detect a localized kinematic bipolar structure in the HD 163296 disk present inside the deepest dust gap at 48 au from atomic carbon line emission. HD 163296's stellar jet and molecular winds have been described in detail in the literature; however, the kinematic anomaly in C i emission is not associated with either of them. Further, the velocity of the kinematic structure points indicates a component fast enough to differentiate it from the Keplerian profile of the disk, and its atomic nature hints at a localized UV source strong enough to dissociate CO and launch a C i outflow or a strong polar flow from the upper layers of the disk. By discarding the stellar jet and previously observed molecular winds, we explore different sources for this kinematic feature in C i emission that could be associated with a protoplanet inflow/outflow or disk winds.

STRUCTURAL - MORPHOLOGICAL SYNTHESIS OF PARALLEL KINEMATICS-BASED HYBRID 3D-PRINTER AND CONNECTION WITH THE CHALLENGES OF INDUSTRY 4.0

This article highlights the application of a systematic method, a structural - morphological approach to the synthesis of new technical solutions in the field of additive technologies to meet the challenges of Industry 4.0, namely the synthesis of a hybrid, fully automated 3D printer with parallel kinematic structures.

Living on the edge of the Milky Way's central molecular zone

Context.The 1°.3 (G1.3) and 1°.6 (G1.6) cloud complexes in the central molecular zone (CMZ) of our Galaxy have been proposed to possibly reside at the intersection region of the X1 and X2 orbits for several reasons. This includes the detection of co-spatial low- and high-velocity clouds, high velocity dispersion, high fractional molecular abundances of shock-tracing molecules, and kinetic temperatures that are higher than for usual CMZ clouds.Aims.By investigating the morphology and deriving physical properties as well as chemical composition, we want to find the origin of the turbulent gas and, in particular, whether evidence of an interaction between clouds can be identified.Methods.We mapped both cloud complexes in molecular lines in the frequency range from 85 to 117 GHz with the IRAM 30 m telescope. The APEX 12m telescope was used to observe higher frequency transitions between 210 and 475 GHz from selected molecules that are emitted from higher energy levels. We performed non-local thermodynamic equilibrium (non-LTE) modelling of the emission of an ensemble of CH3CN lines to derive kinetic temperatures and H2volume densities. These were used as starting points for non-LTE modelling of other molecules, for which column densities and abundances were determined and compared with values found for other sources in the CMZ.Results.The kinematic structure of G1.3 reveals an ‘emission bridge’ at intermediate velocities (~150 km s−1) connecting low-velocity (~100 km s−1) and high-velocity (~180 km s−1) gas and an overall fluffy shell-like structure. These may represent observational evidence of cloud-cloud interactions. Low- and high-velocity gas components in G1.6 do not show this type of evidence of an interaction, suggesting that they are spatially separated. We selected three positions in each cloud complex for further analysis. Each position reveals several gas components at various peak velocities and of various line widths. We derived kinetic temperatures of 60–100 K and H2volume densities of 104–105cm−3in both complexes. Molecular abundances relative to H2suggest a similar chemistry of the two clouds, which is moreover similar to that of other GC clouds and, especially, agrees well with that of G+0.693 and G−0.11.Conclusions.We conclude that G1.3 may indeed exhibit signs of cloud-cloud interactions. In particular, we propose an interaction of gas that is accreted from the near-side dust lane to the CMZ, with gas pre-existing at this location. Low- and high-velocity components in G1.6 are rather coincidentally observed along the same line of sight. They may be associated with either overshot decelerated gas from the far-side dust line or actual CMZ gas and high-velocity gas moving on a dust lane. These scenarios would be in agreement with numerical simulations.