Shape Of Track Research Articles

Design and performance evaluation of a spiral bar precision weeding mechanism for corn fields

This paper focuses on addressing the limitations of existing mechanical weeding methods for corn plants by introducing a spiral tendon-type precision weeding device specifically designed for corn fields. The study encompasses mechanical design and theoretical analysis to determine the overall structure, component parts, application scenarios, operation modes, and working principles of the device. The force applied to the spiral tendon weeding cutter head, a crucial working component of the device, is analyzed, along with its motion characteristics. This analysis allows for the calculation of the force required for the spiral tendon to penetrate the soil, as well as the determination of its trajectory and speed in the soil. The desired motion pattern of the weeding cutter head is considered in determining the contour shape of the inner cylinder track and its cooperation mode with the roller follower. Furthermore, the design and optimization of the circulation groove track are conducted to derive the key parameters of the track. A prototype is then constructed based on the proposed structural design and parameter optimization scheme. Soil bin tests are performed to evaluate the device’s performance. The optimal combinations of working parameters are determined as follows: a 70-mm depth of the weeding cutter head into the soil, a movement speed of 80 mm/s, and an output thrust of the electric actuator of 180 N. Under these conditions, the device achieves a weed removal rate exceeding 95% with a 3% wounding rate, demonstrating stable operational performance.

Influence of parameters of molding by the selective laser melting method on product quality

Purpose. The development and application of additive technologies, which have a high rate of material utilization and significant production flexibility in the case of single and small-scale production, are relevant for solving various types of engineering problems. The final mechanical, technological and operational characteristics of products obtained by additive technologies are affected by a large number of initial parameters that can be varied in order to obtain the necessary properties of the material. The purpose of this work is to study the influence of the parameters of shape formation by the method of selective laser melting, in particular the scanning plan, on the quality of the material and the productivity of production. The methods. To achieve the goal, studies of the microstructure of products obtained by different scanning plans were carried out using optical microscopy, during which the shape of a single track, as well as the structure of the material in different directions of the laser beam, were analyzed. Findings. The effect of particle size, the mechanism of formation of a metal product during selective laser melting is analyzed. The influence of the scanning plan on the porosity, strength, and productivity of manufacturing by the method of selective laser melting is shown. The correct choice of technological parameters, such as the power and speed of the laser beam, the thickness of the metal powder layer, the scanning step between two adjacent single tracks, ensures the minimization of the number and size of defects (pores, cracks, shells) in the product material. The originality. The process of metal powder melting in the process of shaping products by the method of selective laser melting is analyzed. The scheme of formation of a single track is obtained in the case of choosing different scanning schemes. A list of technological parameters, the variation of which affects the properties and quality of the product, has been formed. Practical implementation. The use of additive technologies for the molding of products in single and small-batch production allows to reduce the time of production preparation and reduce the amount of waste. When choosing technological parameters, one should understand their dependence on the final properties of the finished product, because the method of selective laser melting allows to obtain products of different porosity, strength and other properties.

A Maximum Power Point Tracking Control Method Based on Rotor Speed PDF Shape for Wind Turbines

Maximum power point tracking (MPPT) is the key to improve the conversion efficiency of wind energy. Concerning the current research on the MPPT control, based on the accurate tracking of rotor speed probability density function (PDF) shape for wind turbines, a novel MPPT algorithm was introduced in detail to improve the power capture and reduce mechanical damage for wind turbines. Considering the influence of wind speed distribution on the wind power generation system performance, this paper expounds a PDF shape control method of a stochastic system based on the Fokker–Planck–Kolmogorov (FPK) equation. Combining the conventional optimal torque (OT) control algorithm with the FPK equation solved by linear least-square (LLS) method, the novel MPPT control law is designed to make the PDF shape of rotor speed track the desired PDF shape as accurately as possible. The simulation verification of the novel MPPT method is carried out in the 1.5 MW wind turbine system. The results reveal that the novel MPPT method can improve the conversion efficiency of wind energy, reduce the frequent fluctuations of system variables, and significantly optimize the performance of wind power generation system.

Domain Wall Leaky Integrate-and-Fire Neurons With Shape-Based Configurable Activation Functions

Complementary metal oxide semiconductor (CMOS) devices display volatile characteristics, and are not well suited for analog applications such as neuromorphic computing. Spintronic devices, on the other hand, exhibit both non-volatile and analog features, which are well-suited to neuromorphic computing. Consequently, these novel devices are at the forefront of beyond-CMOS artificial intelligence applications. However, a large quantity of these artificial neuromorphic devices still require the use of CMOS, which decreases the efficiency of the system. To resolve this, we have previously proposed a number of artificial neurons and synapses that do not require CMOS for operation. Although these devices are a significant improvement over previous renditions, their ability to enable neural network learning and recognition is limited by their intrinsic activation functions. This work proposes modifications to these spintronic neurons that enable configuration of the activation functions through control of the shape of a magnetic domain wall track. Linear and sigmoidal activation functions are demonstrated in this work, which can be extended through a similar approach to enable a wide variety of activation functions.

Theoretical trafficability criterion and diagrammatic analysis based on rheological property of sea-floor sediment and topography

Trafficability criterion of a tracked miner is investigated when walking across deep-sea floor with obstacles by analyzing the mechanical property of deep-sea sediment and geometrical conditions of obstacles. Trafficability criterion can help predict and estimate the mining efficiency and working safety of the tracked miner on the deep-sea sediment. Deep-sea sediment has an obvious rheological property and its compression-sinkage-time relationship was adopted to describe the sinkage shape of track under different grounding pressure distributions. The area of the sinkage shape was classified and redefined according to the relationships with different traction forces based on work-energy theorem concept. A new trafficability criterion is then established based on the areas of sinkage shapes and the physical meaning of parameters in the criterion was explained diagrammatically in detail. As an application, a trafficable deep-sea ditch width and slope angle were calculated theoretically by combining the trafficability criterion and sinkage shapes analyses. The trafficability criterion is proved to be convenient and intuitive for quickly judging the trafficability problem of deep-sea tracked miner for common obstacles.

Variable Circumstellar Extinction in UX Ori Stars of Late Spectral Types: V695 Per

Eclipses of young stars by dust fragments in protoplanetary disks are the main reason for stochastic variability in the luminosity of UX Ori stars. In analyses and modeling of these kinds of eclipses, the star is often treated as a point light source. This approach is fully justified in the case of hot stars in this family, since the sublimation radius for the dust in their circumstellar disk is much greater than the star’s radius. This approach may not apply to the case of cold stars, since the evaporation zone for the circumstellar dust is close to the star. Here it is shown that accounting for the finite size of the radiation source leads to a change in the shape of a color track on a “color-magnitude” diagram. Calculations for the star V695 Per simultaneously illustrate the variability of the brightness of UX Ori and AA Tau stars for the coldest currently known star of this type.

Numerical modelling of the impact of energy distribution and Marangoni surface tension on track shape in selective laser melting of ceramic material

The present study is based on a formerly developed 3D finite element modelling of the selective laser melting process (SLM) at the track scale. This numerical model is used to assess the impact of two phenomena on the shape of the elementary track resulting from SLM processing: laser interaction on one hand, and Marangoni effect on the other hand. As regards laser interaction, it is modelled by a Beer-Lambert type heat source, in which lateral scattering and material absorption are considered through two characteristic parameters. The impact of these parameters is shown in terms of width and depth of melted zone. The Marangoni effect caused by tangential gradients of surface tension is modelled to simulate the fluid dynamics in the melt pool. The resulting convection flow is demonstrated with surface tension values either increasing or decreasing with temperature. The influence of energy distribution, surface tension effects, as well as laser scanning speed on temperature distribution and melt pool geometry is investigated. The stability and regularity of the solidified track are a direct output of the simulations, and their variations with material and process conditions are discussed.

Selective laser melting of Co-29Cr-6Mo alloy with laser power 180–360 W: Cellular growth, intercellular spacing and the related thermal condition

A feature of solidification during selective laser melting (SLM) is cellular growth. Thus, how growth direction and cell size may be affected and possibly be controlled by SLM parameters are important to be understood. Furthermore, intercellular spacing (λ1) is suggestive of the thermal condition during solidification which needs to be known for advancing the understanding of SLM. In this work, grain solidification orientation and λ1 of a Co-Cr-Mo alloy produced by SLM over a range of laser power (P=180–360W) with other parameters kept unchanged have been evaluated. It has been found that the overall preferred growth of cellular solidification is not significantly affected by P. This is because, over the range of P values used, the shape of track did not change sufficiently to result in a significant variation of growth direction during epitaxial growth. It has also been found that P does not affect λ1. This suggests, since growth rate (R) relates to scan speed (v) which is unchanged, P does not significantly affect the temperature gradient of the solidification front (G). From the measured λ1 and estimated R, G and thus cooling rate (Ṫ) can be estimated following the commonly used primary arm spacing model. The estimated G and Ṫ which could not be directly measured will be compared with those predicted by simulation and the estimated Ṫ will also be compared with those determined by using an emperical relationship from literature.

Analysis of morphology and residual porosity in selective laser melting of Fe powders using single track experiments

Morphology and residual porosity of single tracks obtained by pulse selective laser melting (SLM) of Fe powder have been studied by metallography. Multiple cross sections of the stainless substrate with the single tracks deposited by SLM are examined and classified depending on processing parameters. A sustainable scanning strategy to reduce residual porosity is suggested for pulse laser annealing. The developed method is suitable both for improvement of processing regimes in commercial SLM machines and validation of numerical models in additive manufacturing of metal parts. The effect of the beam radius, pulse energy, its frequency and duration on a shape of the single track and its adhesion to the substrate is revealed.

Influence of a shape of single track on deposition efficiency of 316L stainless steel powder in cold spray

Abstract In current study the kinetics of thick single track formation during cold spraying of 316L stainless steel powder is considered. It is shown that at low nozzle traverse speed the tracks have triangular-like profiles and powder deposition efficiency significantly depends on the triangle height. In particular, increasing of track height leads to significant decreasing of deposition efficiency (more than 35%) due to diminishing of effective impact angle between particles and surface. Numerical simulation results show that parameters of near-substrate compressed gas layer change during coating growth. Compressed gas layer becomes thicker at the jet periphery that decreases particle impact velocity that also influences the particle deposition efficiency in this zone.

‘Don't let me go! Hold me down!’: inspiration, voice and image in Kate Bush's ‘Hounds of Love’

AbstractAlthough Kate Bush's reputation as a significant musical pioneer has been accepted by most critics and academic commentators since her return to music in 2005, most readings of her work have been highly ahistoric. This paper explores how, with the release of her fifth album, Hounds of Love, in 1985, her popular appeal was widened into a genuine acceptance of her idiom by contemporary cultural commentators. In particular, the paper focuses on the rival inspirations and the shape, form and delivery of the title track, ‘Hounds of Love’ and its ‘alternative’ version, released on a 12” disc. The paper concludes by analysing the visual presentation of the song through the promotional video (directed by Bush herself) and her two mimed performances and offering a contextualised explanation for Bush's perceived ‘authenticity’ as an artist and performer.

Determination of Calculation for the Shape of Blades Trace in the Concrete Mixer Truck

Abstract The article deals with a calculation of parameters of blades track for a concrete mixer truck, according to which the blades are placed inside a conical drum in the direction of the helix and are welded then. The issue dealt with is important for accurate determination of the shape of the blades traces according to which the shape of the shanks is drawn inside the drum and the blades are welded after their application inside the drum. The correct shape of the blades track and positioning of the blades in the direction of the helix, as well as the correct welding all affect the concrete consistency during its transport to the final destination. For automated calculation, a mathematical analysis based on theoretical review of the issue is provided in the article. The analysis is done with the use of differential geometry which is optimal for this issue. The results are summarized in a flowchart and the calculation itself is done in the programming environment of Turbo Pascal.

The Role of Extratropical Cyclones and Fronts for Southern Ocean Freshwater Fluxes

Abstract In this study, the important role of extratropical cyclones and fronts for the atmospheric freshwater flux over the Southern Ocean is analyzed. Based on the Interim ECMWF Re-Analysis (ERA-Interim), the freshwater flux associated with cyclones is quantified and it is revealed that the structure of the Southern Hemispheric storm track is strongly imprinted on the climatological freshwater flux. In particular, during austral winter the spiraliform shape of the storm track leads to a band of negative freshwater flux bending toward and around Antarctica, complemented by a strong freshwater input into the midlatitude Pacific, associated with the split storm track. The interannual variability of the wintertime high-latitude freshwater flux is shown to be largely determined by the variability of strong precipitation (>75th percentile). Using a novel and comprehensive method to attribute strong precipitation uniquely to cyclones and fronts, it is demonstrated that over the Southern Ocean between 60% and 90% of the strong precipitation events are due to these synoptic systems. Cyclones are the dominant cause of strong precipitation around Antarctica and in the midlatitudes of the Atlantic and the Pacific, while in the south Indian Ocean and the eastern Atlantic fronts bring most of the strong precipitation. A detailed analysis of the spatial variations of intense front and cyclone precipitation associated with the interannual variability of the wintertime frequency of cyclones in the midlatitude and high-latitude branches of the Pacific storm track underpins the importance of considering both fronts and cyclones in the analysis of the interannual variability of freshwater fluxes.

The spectroscopic Hertzsprung-Russell diagram

The Hertzsprung-Russell diagram is an essential diagnostic diagram for stellar structure and evolution, which has now been in use for more than 100 years. Our spectroscopic Hertzsprung-Russell (sHR) diagram shows the inverse of the flux-mean gravity versus the effective temperature. Observed stars whose spectra have been quantitatively analyzed can be entered in this diagram without the knowledge of the stellar distance or absolute brightness. Observed stars can be as conveniently compared to stellar evolution calculations in the sHR diagram as in the Hertzsprung-Russell diagram. However, at the same time, our ordinate is proportional to the stellar mass-to-luminosity ratio, which can thus be directly determined. For intermediate- and low-mass star evolution at constant mass, we show that the shape of an evolutionary track in the sHR diagram is identical to that in the Hertzsprung-Russell diagram. We also demonstrate that for hot stars, their stellar Eddington factor can be directly read off the sHR diagram. For stars near their Eddington limit, we argue that a version of the sHR diagram may be useful where the gravity is exchanged by the effective gravity. We discuss the advantages and limitations of the sHR diagram, and show that it can be fruitfully applied to Galactic stars, but also to stars with known distance, e.g., in the LMC or in galaxies beyond the Local Group.

On the geometry of coating layers formed by overlap

A recursive model is presented for the prediction of the profile of a coating layer formed by single track overlap. A known shape of single track is assumed and on the base of simple physical assumptions the recursive sequence is deduced to construct an entire profile of such coatings. Calculations of these profiles for different basic shapes and overlaps of tracks show the dependence of coating thickness, waviness and cladding angle on these parameters. A generalized formulation of the model based on purely geometric considerations allows for an application towards different types of cladding processes, including multilayer cladding and 3D depositions. The model is tested experimentally for the laser cladding process in two different set-ups. The cladding track is formed by a continuous deposition of metallic particles into the melt-pool formed by a high power laser beam that continuously moves over a substrate. Good agreement with the parabolic shape of a single track and experimental observations of height and waviness was concluded for a wide range of overlap ratios.

Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

As a surface coating technique, laser cladding (LC) has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F) and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr) composite coatings were fabricated by the multilayer laser cladding technique (MLC). An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

Autonomous terrain adaptation and user-friendly tele-operation of wheel-track hybrid mobile robot

This paper presents a terrain-adaptive wheel-track hybrid robot that uses a pair of combined wheel and track systems. The hybrid mobile platform can change the shape of track to adapt to various terrains so that it is able to move fast on flat terrain and to show good performance in overcoming stairs or obstacles. The proposed platform consists of an ordinary wheel structure for fast navigation on flat floors and a transformable tracked structure for climbing stairs effectively. In detail, three track arms installed on each side of the platform are used for the navigation mode transition between flatland navigation and stair climbing. The mode transition is determined and implemented by the adaptive driving mode control of the mobile robot. This wheel-track hybrid mobile platform is evaluated through experiments that assess its navigation performance in real and test-bed environments. This hybrid mobile robot is embodied to perform given tasks in a hazardous environment for surveillance, reconnaissance, and search and rescue applications.

Mineralogy and petrology of Stardust particles encased in the bulb of track 80: TEM investigation of the Wild 2 fine-grained material

We have characterized by transmission electron microscopy the mineralogy of samples extracted from the walls of the Stardust track 80. More than 500 fragments were studied using conventional imaging, electron diffraction and EDX microanalysis. Two categories of particles are distinguishable in equal proportions (wt%). The first one is comprised of relatively large crystalline grains (≈1μm on average), dominated by silicates (olivine and pyroxene). They display a wide range of compositions and microstructures comparable to those found in terminal particles. Minor phases including magnetite and apatite are also present. Their occurrence suggests that the Wild 2 material underwent aqueous alteration to some extent. The second type of particle, called GEMS-like material, is made of silica-rich glassy clumps embedding iron sulfide beads and vesicles. Their microstructure is characteristic of thermally modified particles that have suffered strong interaction with the silica aerogel during the hypervelocity impact. This melted material may form by shedding of melted and vaporized material, but given the shape of the impact track and high diversity of surviving mineral compositions, much of it originated from fine-grained aggregates that disaggregated during the collection. Chemical mapping at the nano-scale allowed the localization of individual components within the silica-rich glass. They are dominated by Mg-rich components with a size less than 300nm. The average composition of this thermally modified material is close to the solar abundance for the major elements Fe, Mg and S. The fine-grained material has probably not been chemically fractionated in the protoplanetary disk before its incorporation in comet Wild 2 unlike the sulfur depleted matrix of chondrites. From these two categories of particles, we deduce that Wild 2 is likely made of an assemblage of relatively large evolved grains (first category) cemented by a fine-grained material with primitive chemistry (second category). The pre-impact configuration of the incident material deduced from this study seems comparable to the matrix of the most primitive chondrites (3.0) or to chondritic porous interplanetary dust particles.

GSV: a web-based genome synteny viewer for customized data.

BackgroundThe analysis of genome synteny is a common practice in comparative genomics. With the advent of DNA sequencing technologies, individual biologists can rapidly produce their genomic sequences of interest. Although web-based synteny visualization tools are convenient for biologists to use, none of the existing ones allow biologists to upload their own data for analysis.ResultsWe have developed the web-based Genome Synteny Viewer (GSV) that allows users to upload two data files for synteny visualization, the mandatory synteny file for specifying genomic positions of conserved regions and the optional genome annotation file. GSV presents two selected genomes in a single integrated view while still retaining the browsing flexibility necessary for exploring individual genomes. Users can browse and filter for genomic regions of interest, change the color or shape of each annotation track as well as re-order, hide or show the tracks dynamically. Additional features include downloadable images, immediate email notification and tracking of usage history. The entire GSV package is also light-weighted which enables easy local installation.ConclusionsGSV provides a unique option for biologists to analyze genome synteny by uploading their own data set to a web-based comparative genome browser. A web server hosting GSV is provided at http://cas-bioinfo.cas.unt.edu/gsv, and the software is also freely available for local installations.

Self-reconfigurable robots: an introduction

Self-reconfigurable robots are constructed of robotic modules that can be connected in many different ways. These modules move in relationship to each other, which allows the robot as a whole to change shape. This shapeshifting makes it possible for the robots to adapt and optimize their shapes for different tasks. Thus, a self-reconfigurable robot can first assume the shape of a rolling track to cover distance quickly, then the shape of a snake to explore a narrow space, and finally the shape of a hexapod to carry an artifact back to the starting point. The field of self-reconfigurable robots has seen significant progress over the last twenty years, and this book collects and synthesizes existing research previously only available in widely scattered individual papers, offering an accessible guide to the latest information on self-reconfigurable robots for researchers and students interested in the field. Self-Reconfigurable Robots focuses on conveying the intuition behind the design and control of self-reconfigurable robots rather than technical details. Suggestions for further reading refer readers to the underlying sources of technical information. The book includes descriptions of existing robots and a brief history of the field; discussion of module design considerations, including module geometry, connector design, and computing and communication infrastructure; an in-depth presentation of strategies for controlling self-reconfiguration and locomotion; and exploration of future research challenges.