Dependence Of Speed Research Articles

THEORETICAL STUDIES OF THE PROCESS OF GRAIN MATERIAL MOVEMENT ON THE SURFACE OF THE STEPPED VIBRATING FEEDER

A mathematical description of the movement of caryopses in the composition of the components of grain material (CGM) on the surface of a stepped vibrating feeder is given when CGM is introduced into the aspiration channel of the separator under the action of vibrations on the CGM. The trajectories of movement of grains on the surface of the vibrating feeder with different sizes were obtained. The obtained equation of the movement of seeds under the action of vibrations makes it possible to determine the dependence of the speed of movement of the material in the CGM layer on a number of factors: the geometric parameters of the vibrating feeder, the angle of material feeding, the initial kinematic mode of the grain material, the indicator of the kinematic mode of the vibrating feeder, and the friction coefficient of the CGM. The process of movement of grain material on the stepped surface of the vibrating feeder has been substantiated, which makes it possible to determine the rational parameters of introducing the CGM into the aspiration channel of the separator and uniform distribution in the channel with the subsequent possibility of its fractionation. The dependence of the function of the flow rate of grain material on the stepped surface of the vibrating feeder is obtained, which makes it possible to determine the parameters of the distribution of grain material over the sectional area of the aspiration channel of the separator. The estimation of the absolute speed of grain material movement on the stepped surface of the vibrating feeder is made on the basis of a mathematical model constructed by hydrodynamic analogy, which in turn predetermines the analysis of the recombination of caryopses along the thickness of the vibrated layer of grain material. According to the established mathematical models, graphical dependences of the absolute speed of movement on time, the trajectories of the array of particles, the calculated trajectories of particles of grain material, which are fed into the pneumatic channel under initial conditions, were built.

МЕТОД РАСЧЕТА СКОРОСТИ ЗВУКА В МОРСКОЙ ВОДЕ ДЛЯ ИЗМЕРЕНИЯ БЫСТРОМЕНЯЮЩИХСЯ ОКЕАНИЧЕСКИХ ПРОЦЕССОВ

The paper presents two compact polynomial equations expressing the dependence of the sound speed of sea water on the input parameters: in situ temperature, hydrostatic pressure and absolute salinity. The equations are obtained by approximating the standard International Thermodynamic Equation of Seawater-2010 (TEOS-10). The first equation is intended to be used for the technical purposes and reproduces the TEOS-10 data on the seawater sound speed over the wide range water environment parameters with a standard deviation of 0.987 cm/s. The second, more accurate equation is for the scientific use and reproduces the TEOS-10 data on the seawater sound speed over the oceanographic range water environment parameters with a standard deviation of 0.113 cm/s. The equations can be used to solve direct and inverse computational problems. In the direct computational problem, the sound speed value is calculated from the three input parameters measured values. In the inverse computational problem, the value of an unknown input parameter is determined from the measured values of the sound speed and two other input parameters. As a result of the experiments, the higher efficiency of the developed equations was confirmed in terms of their speed, saving energy and computer memory in comparison with the use of the International Equation TEOS-10. The developed equations, algorithms and programs for microcontrollers are convenient tools to equip various offshore platforms and especially fastmoving submersibles. The application of these equations makes it possible to obtain experimental data with high accuracy, to carry out measurements in real time in a rapidly changing aquatic environment, which can also be used to correct the movement of the submersibles.

Experimental study of adaptive course controllers with nonlinear modulators for surface ships in shallow water

The present paper proposes a new adaptive controller with nonlinear modulators to improve the controller adaptability and rudder efficiency so that a satisfactory course tracking performance of ships can be achieved. First, a new adaptive control law on basis of Internal Model Control (IMC) is designed to address the speed dependency of the controller. Three types of nonlinear modulators are then added to the developed adaptive controller to increase the rudder efficiency. Subsequently, the control system’s stability is analysed. Both course keeping and changing performance of the proposed controller are investigated via towing tank tests using a ship model of a Liquefied Natural Gas carrier. Finally, the applicability of controllers in shallow water is discussed. During experiments the developed algorithms show satisfactory course tracking ability in shallow and deep water. The advantages of better adaptability and higher rudder efficiency are verified by comparative results. Moreover, the impact of water depth on the controller cannot be ignored.

Impaired feedforward control of movements in pianists with focal dystonia.

Learning accurate and fast movements typically accompanies the modulation of feedforward control. Nevertheless, it remains unclear how motor skill learning modulates feedforward control, such as through maladaptation of the sensorimotor system by extensive training (e.g., task-specific dystonia). Here, we examined the modulation of feedforward control through motor skill learning while focusing on the motion of piano playing at either a natural tempo or the fastest tempo. The current study compared the kinematics and keypress data among individuals in three groups: healthy and well-trained pianists (i.e., subjects with skill learning), non-musicians (i.e., subjects without skill learning), and patients with focal-hand dystonia (FHD) (i.e., subjects with maladaptation by skill learning). Compared to healthy pianists, patients with FHD showed impairment in some feedforward motion components that are relevant to classifying the two playing tempi. However, while focusing on motion components that are irrelevant to the tempo classification, patients with FHD showed movements comparable to those of healthy pianists. Furthermore, patients with FHD demonstrated significantly slower movement times than healthy pianists. Our results suggest that maladaptation by skill learning affects parts of feedforward control rather than its entirety. Nevertheless, the affected feedforward components are relevant to performing movements as fast as possible, which may underlie the speed dependence of dystonic symptoms.

Solar Wind Electron Pressure Gradients, Suprathermal Spectral Hardness, and Strahl Localization Organized by Single-point Measurements of 0.1 nV m−1 Ambipolar E ∥

A new, fast technique to measure the solar wind’s ambipolar E ∥ routinely with 10% precision and accuracy is demonstrated using 4 yr of 1 au electron data from the Wind 3DP experiment. The 3DP electron instrument duty cycle determines E ∥ ≃ 0.1 nV m−1 from a single spectrum over much shorter time intervals than those requiring radial transits for pressure profiles. The measured weak electric field is invariably strong (in the dimensionless sense of Dreicer), with a modal value of , and positively correlated with solar wind speed, while E ∥ decreases with increasing wind speed. These observations establish across all solar wind conditions the nearly equal accelerations provided by E ∥ and coulomb drags on thermal electrons, a central hypothesis of the Steady Electron Runaway Model (SERM) for the solar wind. Filtered E ∥ observations successfully recover previously reported 1 au bulk speed dependence of electron temperature gradients. The filter screens for unstructured spherically symmetric solar wind (USSSW) conditions of solar wind theory. Outside USSSW conditions much shorter scaled pressure gradients (of both signs) and stronger ∣E ∥∣ are observed predominantly in corotating regimes. Consistent with modeling by Dreicer and SERM, the observed spectral hardness of electrons at suprathermal energies is positively correlated with increasing local values of across the 4 yr data set. Virtually all strahl electrons, crucial to the electron heat flux, are shown to be confined within the local closed coulomb separatrix of each spectrum as determined using the locally measured value of .

Effects of plastic deformation and failure on the folding behavior of non‐crosslinked ethylene propylene diene terpolymer composites

Effects of plastic deformation and failure on the folding behavior of non‐crosslinked ethylene propylene diene terpolymer composites

Откачивание воздуха с примесями золотниковым вакуумным насосом

Vacuum pumping systems are widely used in various branches of science and technology. The mathematical model taking into account the hydraulic resistance of the pipeline and the filter of the vacuum pumping system is proposed to study the dynamics of pumping out air with impurities. The dependences of the pumping speed of the spool vacuum pump PKS-016 on the pressure at the pump inlet, the pressure and velocity of gas along the pipeline axis, the mass of argon in the working tank on time are determined. It is shown that in the absence of a mesh filter and a pipeline length of less than 3 m, a simplified mathematical model can be used for the calculation, assuming that the pressures in the working chamber and at the inlet to the spool vacuum pump are equal.

Surface Wind Responses to Mesoscale Sea Surface Temperature over Western Boundary Current Regions Assessed by Spectral Transfer Functions

Abstract Satellite observations have revealed that mesoscale sea surface temperature (SST) perturbations can exert distinct influence on sea surface wind by modifying the overlying atmospheric boundary layer. Recently, spectral transfer functions have been shown to be useful to elucidate the wind response features. Spectral transfer functions can represent spatially lagged responses, their horizontal scale dependence, and background wind speed dependence. By adopting the transfer function analysis, the present study explores seasonality and regional differences in the wind response over the major western boundary current regions. Transfer functions estimated from satellite observations are found to be largely consistent among seasons and regions, suggesting that the underlying dominant dynamics are ubiquitous. Nevertheless, the wind response exhibits statistically significant seasonal and regional differences depending on background wind speed. When background wind is stronger (weaker) than 8.5 m s−1, the wind response is stronger (weaker) in winter than in summer. The Agulhas Retroflection region exhibits stronger wind response typically by 30% than the Gulf Stream and Kuroshio Extension regions. Although observed wind distributions are reasonably reconstructed from the transfer functions and observed SST, surface wind convergence zones along the Gulf Stream and Kuroshio Extension are underrepresented. The state-of-the-art atmospheric reanalysis and regional model represent well the structure of the transfer functions in the wavenumber space. The amplitude is, however, underestimated by typically 30%. The transfer function analysis can be adapted to many other atmospheric responses besides sea surface wind, and thus provide new insights into the climatic role of the mesoscale air–sea coupling.

Speed of sound in QCD matter

We systematically investigate the speed of sound in QCD matter under different conditions in the grand canonical ensemble within the Polyakov loop improved Nambu--Jona-Lasinio (PNJL) model. The numerical results indicate that the dependence of speed of sound on parameters like temperature and chemical potential can be indicative of QCD phase transition. Some new features of speed of sound are discovered, for instance, the hierarchy of sound velocity for $u(d)$ and $s$ quark at low temperature with the increasing chemical potential and the squared sound velocity approaching to almost zero in the critical region. We also formulate the relations between differently defined sound velocity using the fundamental thermodynamic relations. Some conclusions derived are useful for hydrodynamics simulation and calculation of transport coefficient of bulk viscosity.

Influence of wall slip, thixotropy and lubrication regime on the instrumental sensory evaluation of topical formulations.

Drawing parallels from rheotribology can be used to develop a robust instrumental protocol for non-subjective characterization, product development and design of topical dosage forms with desired sensory attributes. However, instrumental characterization of cosmetic products can be influenced by the measurement protocol, thixotropy, flow anomalies like shear banding or wall slip and nature of the film formed on the skin surface. In this study, we evaluated the influence of above parameters on the instrumental sensory evaluation of 12 topical formulations of different galenic forms. Oscillatory strain sweep measurements (SAOS and LAOS) were performed to investigate the influence of frequency and wall slip on the material parameters. The textural attributes at different consumer touchpoints were evaluated by accounting time-dependent simulation of viscoelastic flow. Further, the influence of film thickness and sample drying on the tactile properties of the topical formulations were studied on a non-biological skin model using a sliding probe tribometer. The study shows that the flow properties of the semi-solid formulations depend on the timescale of the problem. A few formulations exhibited wall slip to varying degrees in the linear viscoelastic regime where the behaviour was found not to be characteristic of a particular topical dosage form. The material functions obtained from the Lissajous plots suggest that the non-linear flow behaviour of different galenic forms is least influenced by the boundary conditions imposed by the measurement geometry. The results were statistically analysed using principal component analysis where the attributes used for discriminating skin creams during pick up and rub out are found to be closely associated with non-linear rheology. The friction coefficient exhibited speed dependence where it formed different parametric group with rheological data depending on the lubrication regime. The study highlights that correlations are possible amongst rheological, tribological and instrumental textural analysis data, which can act an impetus for the development of models to predict attributes that drive perception at different consumer touchpoints. However, the choice of instrumental settings, anomalies associated with rheological measurements and friction dependence on a number of parameters can influence the model prediction.

Ocean bubbles under high wind conditions – Part 2: Bubble size distributions and implications for models of bubble dynamics

Abstract. Bubbles formed by breaking waves in the open ocean influence many surface processes but are poorly understood. We report here on detailed bubble size distributions measured during the High Wind Speed Gas Exchange Study (HiWinGS) in the North Atlantic, during four separate storms with hourly averaged wind speeds from 10–27 m s−1. The measurements focus on the deeper plumes formed by advection downwards (at 2 m depth and below), rather than the initial surface distributions. Our results suggest that bubbles reaching a depth of 2 m have already evolved to form a heterogeneous but statistically stable population in the top 1–2 m of the ocean. These shallow bubble populations are carried downwards by coherent near-surface circulations; bubble evolution at greater depths is consistent with control by local gas saturation, surfactant coatings and pressure. We find that at 2 m the maximum bubble radius observed has a very weak wind speed dependence and is too small to be explained by simple buoyancy arguments. For void fractions greater than 10−6, bubble size distributions at 2 m can be fitted by a two-slope power law (with slopes of −0.3 for bubbles of radius <80 µm and −4.4 for larger sizes). If normalised by void fraction, these distributions collapse to a very narrow range, implying that the bubble population is relatively stable and the void fraction is determined by bubbles spreading out in space rather than changing their size over time. In regions with these relatively high void fractions we see no evidence for slow bubble dissolution. When void fractions are below 10−6, the peak volume of the bubble size distribution is more variable and can change systematically across a plume at lower wind speeds, tracking the void fraction. Relatively large bubbles (80 µm in radius) are observed to persist for several hours in some cases, following periods of very high wind. Our results suggest that local gas supersaturation around the bubble plume may have a strong influence on bubble lifetime, but significantly, the gas in the bubbles contained in the deep plumes cannot be responsible for this supersaturation. We propose that the supersaturation is predominately controlled by the dissolution of bubbles in the top metre of the ocean, and that this bulk water is then drawn downwards, surrounding the deep bubble plume and influencing its lifetime. In this scenario, oxygen uptake is associated with deep bubble plumes but is not driven directly by them. We suggest that as bubbles move to depths greater than 2 m, sudden collapse may be more significant as a bubble termination mechanism than slow dissolution, especially in regions of high void fraction. Finally, we present a proposal for the processes and timescales which form and control these deeper bubble plumes.

Inhomogeneous broadening, narrowing and shift of molecular lines under frequent velocity-changing collisions

We demonstrate that speed-dependent hard-collision profiles collapse into a simple Lorentz profile in the regime dominated by the velocity-changing collisions. We present simple analytical formulas for the effective width and shift of the Lorentzian, derived from the speed-dependent collisional broadening and shift. While the effective width increases with speed dependence of collisional shift, it is reduced by speed dependence of collisional width. On the other hand, the effective shift is modified by thermal average of speed dependence of the product of collisional width and shift. We validate these formula numerically applying the quadratic speed dependence of the collisional width and shift.

УСЛОВИЯ РАБОТЫ СЕПАРИРУЮЩЕГО ЭЛЕВАТОРА КАРТОФЕЛЕУБОРОЧНЫХ МАШИН НА ПЕРЕУВЛАЖНЕННЫХ ПОЧВАХ

The high-quality implementation of the technological process of harvesting potatoes largely depends on the separation process. A separating elevator with cleaning rubber-coated blades is proposed in order to improve the process of separation of the soil-tuberous mass and reduce damage to tubers. The conveyor with rubber blades is located inside the main and moving against the direction of the separating elevator movement. Mounted blades with their touch will clean the lumens of the rods from sticking. The quality of the completeness of the separation of potato harvesters depends on the duration of the presence of the soil-tuberous mass on the working surface of the elevator. In the course of theoretical studies, the relative speed of movement of the soil-tuberous mass was analytically determined depending on the change in the mass of the soil layer after the interaction of the blades of the internal conveyor with the elevator bars. The range of change in the rational value of the elevator speed for elliptical shakers was taken into account. The graphs of the dependences of the relative speed of movement of the soil-tuberous mass on the kinematic parameters of the internal conveyor and on the congestion of the elevator are analyzed. It has been established that the interaction of the blades of the internal conveyor with the bars of the elevator has little effect on the speed of the soil layer. The internal conveyor with rubberized blades will clean the gaps between the bars of the elevator without resisting the movement of soil and tuber mass on the surface of the separating elevator, thereby improving the quality of soil separation and reducing damage to tubers.

Asymptotic theory of a flapping wing of a circular cross-section

The paper is devoted to the study of the propulsive motion of a flapping wing of a circular cross-section performing translational–rotational oscillations in a viscous incompressible fluid. To describe the flow past the wing, the unsteady Navier–Stokes equation is solved. Using the method of asymptotic expansions for the case of small amplitudes of oscillations, an analytical solution of the problem is constructed in the first two terms. It is shown that the nonlinear interaction of time harmonics of translational and rotational oscillations causes secondary flows (steady streaming) that make the wing move in the direction perpendicular to the axis of translational oscillations. For the case of cruising motion, when the average hydrodynamic force acting on the wing is equal to zero, the dependence of the average speed on the dimensionless oscillation parameters is found. The results show that for relatively large angles of rotation the cruising speed of a flapping wing can be as high as the velocity amplitude of translational oscillations. The limits of applicability of the asymptotic theory are investigated using direct numerical simulations. Numerical data demonstrate that the theory well describes the flow past the wing in a wide range of dimensionless amplitudes, frequencies and angles of rotation. In conclusion, the efficiency of the propulsion system is evaluated. It is shown that in terms of relative energy consumption, a cylindrical flapping wing can be attributed to the most efficient propulsors in the range of Reynolds numbers $Re \sim 10^2\text {--}10^3$ .

Spatio-temporal wind speed prediction based on Clayton Copula function with deep learning fusion

Accurate prediction of wind speed plays an important role in increasing the power generation of wind turbines and realizing efficient use of wind energy. However, due to the large number of wind turbines in the wind farm and the complex wake effects between the units, the coupling degree and spatial correlation of the wind speed of the wind turbines are increased. Accordingly, this paper proposes a wind speed prediction model based on spatio-temporal dependency analysis. The proposed model first uses long short-term memory(LSTM) neural network to predict the wind speed of each wind turbine to obtain its residuals, which can extract the time correlation of the wind-speed series; Then by applying the Clayton Copula function to analyze the correlation between the residual series and wind-speed series to get the joint-distribution function. The joint-distribution function can be used to calculate the prediction error of the wind speed and complete the wind speed prediction. The validity of the method in this work is verified using the measured wind-speed data of a wind farm. Experimental results show that the method effectively solves the problem of finding spatio-temporal dependency of wind speed and significantly improves the prediction accuracy of wind speed.

Rayleigh-type surface waves in a thermally conducting mixture of an elastic solid and a Newtonian fluid

PurposeThe purpose of this paper is to analyze the propagation characteristics of the Rayleigh-type surface wave in a thermally conducting mixture of an elastic solid and a Newtonian fluid by applying the mixture theory.Design/methodology/approachThe governing equations are formulated in context of both Green–Lindsay (G-L) and Lord–Shulman (L-S) theories of generalized thermoelasticity. The specialized governing equations in a plane are solved by using the traditional approach, and a dispersion equation of the Rayleigh surface wave is obtained.FindingsA program in MATLAB software is developed to solve the dispersion equation. The numerical results demonstrate a significant dependence of the wave speed and the attenuation coefficient of the Rayleigh wave on the frequency and porosity.Originality/valueThe problem considered on Rayleigh wave on the surface of a half-space containing a thermally conducting mixture is not studied in the literature yet. The theoretical and numerical findings of the study will guide the experimental scientists while finding applications in various engineering fields.

On the mechanisms of lightning initiation and positive leader intergrowth

A model of a leader breakdown in air was developed, in which the channel is formed by heating the streamer trace in the leader corona. To determine the initial conditions, the model of a streamer breakdown was proposed. The minimal field intensity required to support the streamer breakdown was determined. The dependence of the leader's speed on the cloud potential was obtained. The lightnings are initiated by relativistic avalanches, the formation threshold field strength of which is below the threshold of the streamer discharge. By comparing the thresholds of relativistic and streamer breakdowns the heights for realization of the proposed initiation mechanism are specified.

Effects of humidity on the dynamics and electron recombination of a pin-to-pin discharge in He + H2O at atmospheric pressure

Control of the plasma chemistry is essential for the effectiveness of atmospheric pressure plasmas in many applications. For this, the effects of the humidity of the feed gas on the discharge chemistry need to be considered. Detailed studies are scarce and many of them are dominated by surface interactions, obscuring any volume effects. Here, a negative nanosecond pulsed discharge is generated in a pin–pin 3 mm gap geometry in He + H2O that enables the study of volume kinetics due to minimal surface area. The effect of humidity on the discharge development, electric field and electron density is investigated through experiments and modelling. It is found that the presence of water vapour affects both the electron density at the start of the pulse (remaining from the previous pulse) and the ionisation rates during the ignition phase, leading to a complex dependence of the discharge development speed depending on the water concentration. The electron decay is studied using the 0D global kinetics model GlobalKin. The dominant reactions responsible for the electron decay depending on the concentration of water vapour are determined by comparing experimental and simulated results and these reactions are grouped in simplified kinetic models. It is found that with water concentrations increasing from 0 to 2500 ppm, the complexity of the dominant reactions increases with in particular O2 +, H2O3 + and water clusters becoming important for high water concentrations. This work also provides experimental data for validation of kinetic models of plasmas in controlled environments.

Study of Underwater and Wave Gliders on the Basis of Simplified Mathematical Models

Both underwater and wave gliders are known as autonomous unmanned energy-saving vehicles which have recently found applications for monitoring the world ocean. The paper under consideration discusses simplified mathematical models of these platforms enabling the straightforward parametric investigation into relationships between their parameters and performance. In its first part the paper discusses equations describing the motion of an underwater glider (UG) in a vertical plane as a basis for derivations relating geometric, kinematic and hydrodynamic characteristics of UG and its lifting system with relative differential buoyancy and pitch angle. Obtained therewith are formulae for the estimation of the UG glide path speed, lift-to-drag ratio, range of navigation and endurance. The approach is exemplified for typical cases of the UG conceived as winged bodies of revolution and flying wings. The calculated results feature dependencies of the UG speed on its configuration and volume as well as on the angle of attack for different magnitudes of relative buoyancy. Also considered is an optimal mode of operation, based on the maximization of the lift-to-drag ratio. The second part of the paper is dedicated to the estimation of the thrust and speed of a wave glider (WG), comprising a surface module (float) and underwater module represented by a wing, with the use of a simplified mathematical modeling intended to clarify the influence of the parameters upon the performance of the WG. The derivations led to an equation of forced oscillations of the vehicle accounting for the interaction of the upper and lower modules, connected by a rigid umbilical. The exciting impact of progressive waves of a given length and amplitude is found through the calculation of the variation of a buoyancy force in accordance with the Froude–Krylov hypothesis. The derivatives of time-varying lift with respect to kinematic parameters, entering the equation of vertical motion of the WG, as well as coefficients of instantaneous and time-averaged thrust force, are found by resorting to the oscillating hydrofoil theory. The derivation of the available thrust and the approximate calculation of the drag of the vehicle with account of wave and viscous components enable the evaluation of the speed of the WG for the prescribed geometry of the craft and wave motion parameters.

Rolling Bearing Condition Monitoring Technique Based on Cage Rotation Analysis and Acoustic Emission

The objective of this paper is to present an approach for the detection of change in rolling element bearings (REB) operating conditions that can lead to premature failure. The developed technique is based on the measurement of the kinematics of the bearing cage. The rotational motion of the cage is driven by the traction forces produced in the contacts of the rolling elements with the races. It is known that the cage angular frequency relative to shaft angular frequency is dependent of the bearing load, the bearing speed and the lubrication condition, as these factors are determinant for the lubricant film thickness and the associated traction forces. As an important part of REB failures are caused by misalignment or lubrication problems, any evidence of these conditions should be interpreted as an incipient fault. In this paper a novel method for the determination of the instantaneous angular speed (IAS) of the cage is developed. The method is evaluated in a deep grove ball bearing test rig equipped with the cage IAS sensor, as well as custom acoustic emission (AE) transducer and a piezoelectric accelerometer. The cage IAS is analyzed under different bearing loads and shaft speed, showing the dependence of the cage angular speed with the calculated lubricant film thickness. Typical bearing faulty operating conditions (mixed lubrication regime, lubricant depletion and misalignment) are recreated and it is shown that the cage IAS is dependent on the lubrication regime and is sensitive to misalignment. The AE signal is used as a lubrication regime evaluator as well. Experimental results show that the proposed technique can be used as a condition monitoring tool to detect abnormal REB conditions that can lead to premature failure.