Curvilinear Movement Research Articles

The effect of a malfunctioning braking system on the behaviour of a special vehicle during an emergency braking in a curvilinear movement

Vehicle mobility is an increasingly important issue today, even in the military field. Mobility depends on the condition of the vehicle, the route and, of course, the experience of the driver. Vehicle failures and damage are very common in military operations. It is therefore important to find out how these failures and damage can affect mobility. One of the essential parts of a vehicle is the braking system. The authors therefore decided to investigate what is the effect of a malfunctioning brake system on emergency braking behaviour of a special vehicle in a curvilinear movement. Simulation tests were performed based on an experimentally validated model. The tests were performed with a wheeled vehicle on three different surfaces: concrete, wet asphalt, and ice. The experimental conditions were given as follows – the braking process was considered for a braking system with ABS on and off and for two states of braking system sufficiency (8 braked wheels or 4 rear braked wheels). These tests allowed us to analyse the effect of the extent of the damage on safety, in this case the stopping of the vehicle on a specified curved route. The results of braking and stability on different surfaces and under given conditions are evaluated and described in this paper. On the basis of the results, it is possible to prepare training programmes (scenarios) for drivers of special vehicles for the purpose of driving techniques in critical situations.

Methodology for experimental evaluation of the increase in resistance during curvilinear movement of a wheeled vehicle

The article presents a method for obtaining computational and experimental dependencies that describe the increase in resistance during the curvilinear movement of a wheeled vehicle along a non-deformable, flat horizontal supporting surface on the speed and curvature of the trajectory. The set of parameters controlled during the experiment includes information about the force factors on the axis of the wheel propulsion device; in this regard, the work examines the main features of processing data obtained using strain gauge wheels. The main distinctive feature of the proposed approach to assessing the increase in resistance during curvilinear movement is the ability to take into account the design features of the rotation of a wheeled vehicle as a whole, for example, the discrepancy between the steering angles of the steering wheels and the geometry of the steering linkage (Ackermann geometry), etc. It should be noted that these features are difficult to take into account analytically in simplified mathematical models of vehicle dynamics, for example, used to solve problems of optimization of the laws of motion, which makes this research relevant. Keywords wheeled vehicle, curvilinear motion, full-scale experiment, energy efficiency, motion resistance

Дослідження гальмівної динаміки автопоїзда

The article analyzes the dynamic characteristics of the braking process of a two-link road train during straight and curvilinear movement. It has been proven that the greatest indicator of the efficiency of the braking process of a road train is observed during full loading of all axles, that is, when all wheels are on the verge of blocking at the same time, and the stability of the movement of the road train in the braking mode depends on the proportionality of the braking forces to the value of the normal reactions on each wheel and the nature of the interaction of the links in the support-coupling device. Dependencies for calculating the value of the normal reactions acting on the wheels of the vehicle have been obtained. It was established that when the weight of the semi-trailer changes, the largest additional load occurs on the axle of the semi-trailer, the smallest - on the front axle of the tractor. During braking in the process of straight-line movement, with increased braking intensity, the load on the rear axle of the tractor, as well as the axles of the semi-trailer, is reduced by increasing the load on the front axle of the tractor. It should be noted that simultaneously with the unloading of the axles of the semi-trailer, there is an increase in the load on the support-coupling device of the vehicle, which, in turn, results in an increase in the load on the axles of the tractor. Braking dynamics of a road train in curvilinear movement shows that an increase in the intensity of braking is accompanied by a redistribution of the values of normal support reactions and additional loading of the front axle of the tractor. At the same time, a larger value of the normal reaction is characteristic of the wheels located on the outer circle relative to the center of rotation. This effect is explained by the influence of centrifugal forces. The maximum value of lateral deviation of normal support reactions is observed on the rear axle of the tractor.

Bull Semen Obtained on Beef Farms by Electroejaculation: Sperm Quality in the First Two Hours of Storing with Different Extenders and Holding Temperatures.

Sperm quality decreases over time, so bull semen may need to be preserved after field collection. However, the effect of handling such semen samples from commercial farms and placing them in very short-term storage has not been elucidated. Therefore, ejaculate from 25 bulls from 1 dairy and 14 beef cattle farms were collected under farm conditions and evaluated for semen quality during the first two hours after collection. Two commercial extenders (AndroMed® and BIOXcell®) and two different storage temperatures (5 °C and room temperature) were used to evaluate the influence on semen quality and sperm kinetics in ejaculates grouped into three evaluation times, based on time since collection (Time 1: <75 min, n = 7; Time 2: 75-105 min, n = 11; and Time 3: 105-120 min, n = 7). Classical semen parameters, sperm motion kinetics by CASA and colony-forming units were assessed. The differences between both extenders in curvilinear and straight-line velocities (VCL and VSL) for the different time groups (Time 2 and Time 3) were statistically significant for p < 0.05. AndroMed® showed lower VSL, straightness and linearity in sperm compared to BIOXcell® (p < 0.05). In conclusion, AndroMed® induced more curvilinear movement, while BIOXcell® stimulated straighter motility.

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ РОБОТИ СУДНОВИХ СТЕРН ПРИ РІЗНИХ РЕЖИМАХ МАНЕВРУВАННЯ

The availability of adequate mathematical models of the ship propulsion system is essential for developing effective ship control systems, building high-quality simulators, and studying the ship’s maneuvering behavior. With the advancement of new computing and information technologies, the mathematical models of the ship propulsion system need to meet higher requirements and cover wider applications. This leads to the need for continuous improvement of mathematical models, especially those of non-inertial forces acting on the ship. This work investigates the influence of the ship’s curvilinear movement on the rudder performance. Mathematical models of the forces and moments acting on the rudder at different values of the local drift angle and the rudder angle are derived. The resultant force on the rudder is decomposed into components due to the rudder lift, drag, normal force, and tangential force. Expressions for the coefficients of rudder hydrodynamic quality, reverse quality, and normal force are obtained. The existing mathematical models of the rudder hydrodynamic coefficients are analyzed and their limitations and applicability are discussed. New mathematical models of the rudder lift and drag coefficients are proposed, which take into account the aspect ratio, relative thickness, and angle of attack of the rudder. The proposed models are validated by comparing them with experimental data for NACA series rudders. t is shown how the lift and drag of the rudder, as well as the components of the resulting force, change for the maximum possible range of changes in the local drift angle and the rudder angle, for different values of the rudder aspect ratio and relative thickness. Keywords: mathematical models, ship rudders, curvilinear movement, longitudinal and transverse components of forces, dimensionless hydrodynamic coefficients.

Curvilinear motion control laws for a semi-trailer caterpillar train for off-road cargo transportation

BACKGROUND: For transport accessibility in areas with an undeveloped road network, the use of tracked trains that provide low ground pressure is a rational solution. To ensure the mobility of a semi-trailed, unmanned caterpillar train, which can be controlled remotely by a driver-operator or by an automatic unmanned driving system, traffic control laws are needed.&#x0D; AIMS: Ensuring energy efficiency in curve control of a unmanned semi-trailer tracked train for off-road freight transport.&#x0D; METHODS: The methods of simulation mathematical modelling and analytical methods based on the consideration of the quasi-stationary motion of the caterpillar train links are used to derive energy-efficient control laws and determine the mobility performance that can be achieved.&#x0D; RESULTS: Control laws are obtained for two variants of tracked trains: a tracked train with independent drive control of driving wheels and a tracked train with a differential drive scheme of a semi-trailer link. The control laws are designed to improve the energy efficiency of travel which is achieved by rational distribution of traction forces on the driving wheels of the tracked train and use of the regulator which ensures adjustment of the traction on the semi-trailer driving wheels accord-ing to the sign and magnitude of force in the fifth-wheel coupling of the tractor.&#x0D; A block diagram of a governing system of a caterpillar train and a mathematical description of its basic structural components (blocks) are given. Using the developed control laws the theoretical research of curvilinear movement by simulation mathematical modelling is carried out; the comparative analysis of the considered control laws of the semitrailer caterpillar train movement with two transmission variants is given.&#x0D; CONCLUSIONS: The application of the developed caterpillar train motion control laws will enable the vehicle to move unmanned or follow the lead vehicle along a set path with high accuracy of turning manoeuvres and, consequently, will improve the safety of freight transportation.

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ ПРОЦЕССА КОМБИНИРОВАННОЙ РЫЧАЖНО-ЭЛЕКТРОМАГНИТНОЙ СИСТЕМЫ ПОПЕРЕЧНОЙ СТАБИЛИЗАЦИИ

The article developed a block diagram and mathematical models of the processes of the lever-electromagnetic system of lateral stabilization in order to analyze the change in the roll angle of the GAZelle NEXT all-metal van during curvilinear movement with a lever stabilizer (without EMC) and using a system of lever-electromagnetic stabilization (with EMC). Modeling of a lever-electromagnetic transverse stabilization system with and without EMS in the Matlab&amp;Simulink system is presented. As a result of modeling curvilinear motion, the effectiveness of using a lever-electromagnetic stabilization system (EMS) was proved in comparison with lever stabilizers (with-out EMS) based on a comparison of roll angles.

Evaluation of maxillary canine and molar movement during the first phase of extraction space closure: a multilevel analysis.

This study was designed to analyze and compare the cusp and apex movements of the maxillary canines and first molars during canine retraction in the first step of extraction space closure, and to evaluate if these teeth follow a curvilinear (acceleration and/or deceleration) movement rate. Twenty-five patients (23.3 ± 5.1 years of age) were enrolled. The retraction of the maxillary canines was accomplished using nickel-titanium closed coil springs (100gf) on 0.020-in stainless steel archwire. Oblique cephalograms were traced and superimposed on the anatomic best fit of the maxilla (before the retraction [T0], and after one month [T1], three [T3], five [T5] and seven [T7] months). Statistics was based in a normally distributed data. Multilevel procedures were used to derive polynomials for each of the measurements. Student's t-test and one-way repeated measures ANOVA were conducted. The level of significance of 5% was adopted. Canine cusps and apexes did not follow a quadratic curve regarding horizontal movement (neither accelerate nor decelerate). Canine and molar cusps showed more horizontal movement than apexes (4.80 mm vs. 2.78 mm, and 2.64 mm vs. 2.17 mm, respectively). Canine did not accelerate or decelerate overtime horizontally; the cusps and apexes of the canines and molars showed more horizontal movement and larger rate at the beginning of canine retraction, followed by significantly smaller and constant movement rate after the first month.

Determination of the parameters of the curvilinear movement of vehicles

Today, the creation of new vehicles is impossible without computer modeling. Modern vehicles have numerous electronic systems that increase its traffic safety, comfort, and route planning management. Reliable operation of all systems is achieved by using an accurate dynamic model of the vehicle to assess safety and the possibility of movement along specified trajectories. Creating an accurate dynamic vehicle model requires correct initial parameters. When modeling the curvilinear movement of motor vehicles, such parameters as the coefficients of resistance to lateral sliding of tires and the angles of sliding of axles, which are mainly determined on test benches in laboratory conditions, are important to obtain the adequacy of the object under study. However, quite often it is impossible to obtain reliable information from tire manufacturers or testing laboratories, which ultimately affects the adequacy of modeling the parameters of vehicle movement. A method is proposed for determining the design parameters of tires using primary information sensors, which are sensors of angular and linear velocities, linear accelerations, rotation angles of controlled wheels and an on-board information processing device. The advantages of this method are that it allows real-time measurement of the angles of the axles and the coefficients of resistance to the lateral withdrawal of the axles when the vehicle is moving at an arbitrary speed along a trajectory of variable curvature. This method can be used to create an accurate dynamic model in the study of the controllability and stability of the vehicle, as well as an integral part of the vehicle dynamics control system.

Development of a user interface for input of a curvilinear object movement trajectory with variable speed

The article considers the development of an interface for the most accurate input by the user of the trajectory of the curvilinear movement of the ship in the marine environment with variable speed for the further development of software for modeling the marine water area. Convenient modeling of objects in the sea water area requires a convenient interface that allows the user not only to set an arbitrary curvilinear trajectory of movement, but also checks the possibility of movement of the given object in relation to its size and speed of movement. Therefore, for the implementation of an interactive interface for entering a curvilinear trajectory of a ship, it is necessary to take into account the dynamics of the controlled object. When evaluating the trajectory, the physical limitations of the vessel must be satisfied. They determine the minimum radius of curvature, tangential acceleration and all three speeds (longitudinal, transverse, angular). The projected trajectory should be smooth, and its speeds along all three axes should be constant. Taking into account information about the physical forces affecting the movement of the ship, the formulas for calculating the points of the trajectory were derived, which are subsequently used both for visual representation and for calculations in the simulation of the experiment. The problem was divided to 3 parts: linear movement, the movement along the arc of the circle, movement after the turn. The algorithm for getting the position of the ship at any point of time during the turn was provided/. The article also provides an example of coding derived formulas using C# programming language. The results were provided by demonstrating the developed interface.

The effects of robotic assistance on upper limb spatial muscle synergies in healthy people during planar upper-limb training.

BackgroundRobotic rehabilitation is a commonly adopted technique used to restore motor functionality of neurological patients. However, despite promising results were achieved, the effects of human-robot interaction on human motor control and the recovery mechanisms induced with robot assistance can be further investigated even on healthy subjects before translating to clinical practice. In this study, we adopt a standard paradigm for upper-limb rehabilitation (a planar device with assistive control) with linear and challenging curvilinear trajectories to investigate the effect of the assistance in human-robot interaction in healthy people.MethodsTen healthy subjects were instructed to perform a large set of radial and curvilinear movements in two interaction modes: 1) free movement (subjects hold the robot handle with no assistance) and 2) assisted movement (with a force tunnel assistance paradigm). Kinematics and EMGs from representative upper-limb muscles were recorded to extract phasic muscle synergies. The free and assisted interaction modes were compared assessing the level of assistance, error, and muscle synergy comparison between the two interaction modes.ResultsIt was found that in free movement error magnitude is higher than with assistance, proving that task complexity required assistance also on healthy controls. Moreover, curvilinear tasks require more assistance than standard radial paths and error is higher. Interestingly, while assistance improved task performance, we found only a slight modification of phasic synergies when comparing assisted and free movement.ConclusionsWe found that on healthy people, the effect of assistance was significant on task performance, but limited on muscle synergies. The findings of this study can find applications for assessing human-robot interaction and to design training to maximize motor recovery.

Justification principles of movement stabilization of an articulated electric bus with a rear pushing section

Introduction (statement of the problem and relevance). Currently, the need for intra-city passenger transportation is becoming more acute. High-capacity and electric buses, including articulated and double-decker ones, have proven their efficiency both in Russia and abroad and are widespread. The fact is especially important for the cities that do not have a network of high-speed transport. As a result, in these cities the passenger traffic load falls on ground transport, the main type of which is a bus or an electric bus.The purpose of the study was to increase the stability of an articulated electric bus with a rear pushing section in motion introducing an elastic-damping connection in the articulation unit.Methodology and research methods. Simulation modeling methods were used.Scientific novelty and results. It was shown that the stable movement of an articulated electric bus with a rear driving axle could be ensured by introducing an elastic-damping connection in the coupling device. The damping coefficient must be variable and dependent on the folding sections angle of the electric bus. A hydraulic system scheme for an electric bus coupling was proposed, consisting of two hydraulic cylinders, a hydraulic accumulator and spool devices, which ensured the creation of an elastic-damping connection between the sections. The differential equations analysis of the front section motion showed that its rectilinear motion was unstable. To ensure the stability of its movement in the electric bus articulation, it was necessary to create an elastic restoring moment directed against the folding sections angle. Curvilinear movement of the rear section was stable.Practical significance. It has been established that the introduction of variable throttling in the sections folding system of an articulated electric bus with a rear pushing section increases the stability of its movement when making a “turn” maneuver on supporting surfaces with low grip properties.

Risk Prediction of Ureaplasma urealyticum Affecting Sperm Quality Based on Mathematical Model and Cross-Sectional Study.

Objective To explore the risk of Ureaplasma urealyticum (UU) affecting sperm quality. Methods Prospective cross-sectional study was conducted. In total, 340 semen samples were collected. According to whether they were infected with UU, the samples were divided into the UU-positive group (observation group) and UU-negative group (control group). The patients with UU-positive were followed up to obtain treatment and collected the semen again after treatment. The semen characteristics and sperm parameters were detected and compared, and the relationship of UU and the sperm quality was analyzed by mathematical models. Results There were 104 UU-positive semen samples in all, with an overall infection rate of 30.6%, which was highest in 31 to 40-year-old men, and over 40-year-old men were the lowest. The pH, PR, VCL, VSL, and STR in the observation group were significantly lower than those in the control group (allP < 0.001), while SV, NP, and WOB were significantly higher (allP < 0.001). After treatment, the pH, VSL, LIN, WOB, and STR in the observation group were significantly higher than before (allP < 0.001), while SV and VCL were significantly lower (allP < 0.001). UU infection was closely correlated with pH, PR, NP, VCL, VSL, WOB, and STR. During the treatment, pH, PR, VSL, WOB, and STR increased, but NP and VCL decreased. 7 major factors that would affect SQ were extracted, of which VAP, LIN, and UU were the first three main factors. The risk of SQ declining after UU infection increased nearly twice with the change of PR and VCL and increased 0.08 times with STR. Conclusion UU may approximately double the risk of altering the sperm's curvilinear movement rate and straightness to affect the sperm quality.

MODIFIED METHOD AND DESIGN OF A POWER BRAKE STAND FOR VEHICLE TESTING

The principles of functioning of stands for testing the braking qualities of wheeled vehicles are considered. Their advantages and disadvantages are analyzed. There is a general disadvantage of the most common power brake roller stands in practice – the difference in the shape of the contact spot and the acting forces and reactions of the wheel on the support rollers and in road conditions. As a result of the system analysis of structures, a modified method and design of a power roller stand with an original support device in the form of a horizontally rotating disk are proposed. The description of the principle of implementation of tests on braking qualities and suspension of vehicles is given.&#x0D; A preliminary analysis of the proposed stand design shows that in a static state, the wheel contact spot on such a disk is completely identical to the wheel spot on a horizontal road surface. When the disc rotates and the brake system is tested, the shape of the wheel contact spot on the support disc will change, but, according to the authors, slightly – similar to how the contact spot changes during the curvilinear movement of the car, characteristic of real operating conditions, but how much this will happen is the subject of further research.&#x0D; Purpose – development of a method and design of a stand that provides an increase in the reliability of testing the braking qualities of cars under operating conditions.&#x0D; Methodology system analysis of methods and designs of stands for testing braking qualities and suspension of vehicles, elements of block-modular design.&#x0D; Results: a patentable design of a power stand is proposed, free from the disadvantages of power roller brake stands.&#x0D; Practical implications the obtained results should be used in the creation and production of brake stands for monitoring the technical condition, when diagnosing and conducting technical inspections of vehicles under operating conditions.

Characterization and sex-related differences in the multi-location external workload profile of semiprofessional basketball players. A cross-sectional study

ABSTRACT Commonly, the monitoring of external workload has been performed using a single device on player's scapulae. The human body is a complex multi-articular system and quantification in a single location is insufficient, being necessary the assessment in multiple body locations simultaneously. Therefore, this study aimed to characterize the multi-location external workload in men’s and women’s players and to analyze the sex-related differences during the most common movements in basketball. Twenty-six semi-professional basketball players (n = 13 men, n = 13 women) were evaluated in five tests: linear and curvilinear movements, changing of speed, jumping and in-game movements. PlayerLoadRT was evaluated at six anatomical locations simultaneously (scapulae, lumbar region, knees, and ankles) with WIMU PROTM inertial devices attached to the athlete using a full-body skinsuit. Statistical analysis was composed of a t-test of independent measures and Coheńs d effect size. The main results indicated: (1) the type of movement modified the external workload supported by the musculoskeletal structures; (2) sex-related differences were found in the vertical absorption of external workload (p < 0.05); (3) no sex-related differences were shown in the horizontal profile (p > 0.16). The multi-location monitoring will allow the identification of musculoskeletal structures with high vertical absorption of external load depending on sex (men > women: scapulae-lumbar and knee-ankle; women > men: lumbar-knee) and type of movement (scapulae-lumbar: decelerations; lumbar-knee: jumping; knee-ankle: in-game), just like horizontal differences in lower limb (outer > inner leg: curvilinear). Equally movements distribution throughout training sessions, strengthening and recovery programmes of high-workload muscle groups according to player’s characteristics could contributed to performance enhancement and reduce injury risk. HIGHLIGHTS Men’s and women’s basketball players presented different vertical musculoskeletal absorption of external workload. Men presented higher absorption in scapulae – lumbar and knee – ankle segments while women did so in the lumbar – knee segment. The type of movements had a direct effect in the multi-location external workload profile. A combined effect of sex and type of movement was found in the vertical musculoskeletal absorption of the external workload profile. No sex-related differences were found in the horizontal profile regarding the type of movement.

СТЕНДОВЫЕ ИСПЫТАНИЯ ЭКСПЕРИМЕНТАЛЬНОЙ СЕЯЛКИ ДЛЯ ПОСЕВА ГАЗОННЫХ ТРАВ

The rational movement of a seeding unit when sowing lawn grasses requires the seed drill to move both along straight-line and curvilinear trajectories, thus enabling it to sideslip possible obstacles, while maintaining uniform sowing. To ensure uniform sowing during a curved path, a different amount of seed material is required to enter the soil from the seed wheels, which travel distances of different radii. To check the indices of the non-uniformity of sowing between units and the general variability of sowing at rectilinear and curvilinear movement, the experimental seed drill SV-0.9 equipped with the seeding unit of a reel type was developed and manufactured. It is capable of uniform sowing both at rectilinear and curvilinear movement. The authors present some stand test methods for determining the rate of the non-uniformity of sowing between the units for the experimental seed drill with regard to its ability to provide uniform sowing both at rectilinear and curvilinear movement. Benchmark tests of the experimental seed drill were carried out on seeds with different physical and mechanical properties - white clover and grass mixture “Sportivnaya”. The sowing area was 30 m2. The results of benchmark tests confirmed a linear relationship between the number of the reel grooves and the amount of sowing. It was found that between the units of the seed drill, the index of the non-uniformity of sowing of white clover seeds ranged between 2.23 and 3.10% and of grass mixture - 3.97 and 4.79%, the standard value being 8%. The variability index of the total sowing of white clover seeds was 2.77%; while for grass mixture “Sportivnaya”, this index was 2.95%, the standard value being 9%. The study experimentally confirmed the effectiveness of the developed seed drill for the uniform sowing of lawn grasses.

Alpine Skiing Tracking Method Based on Deep Learning and Correlation Filter

In outdoor sports such as alpine skiing, athletes hope to obtain information such as movement trajectory and speed to achieve scientific training. The portable sensor has a sense of restraint and affects the athlete’s performance. Cameras have difficulty capturing the whole race in an outdoor environment. For alpine skiing needs, we designed an alpine skiing information acquisition system, using unmanned aerial vehicle (UAV) and ground cameras to obtain information on the whole path of the race. The environment of the alpine skiing field, the high-speed curvilinear movement of athletes and the flight characteristics of UAVs cause challenges in the detection and tracking of athletes by UAVs. To realize the detection and tracking of alpine skiing by UAVs, we propose a detection algorithm by combining neural networks and correlation filters. A tracking confidence score based on the motion distance of the interval frame is defined. When the tracking confidence of the neural network detector is less than the threshold, the correlation filter is used to expand the recognition range and realize redetection. In addition, we created and annotated a fresh alpine skiing dataset. We compare our algorithm with four advanced algorithms on the UAV123 dataset. Three methods are used to evaluate the performance of our method on the alpine skiing sequence dataset. From the simulation results, our algorithm outperforms the comparison methods in terms of accuracy and robustness. Therefore, our algorithm has application value in the scientific training of alpine skiers.

МАТЕМАТИЧНЕ МОДЕЛЮВАННЯ РОБОТИ СУДНОВИХ ГВИНТІВ ПРИ РІЗНИХ РЕЖИМАХ МАНЕВРУВАННЯ

In the study of ship maneuvers, in the development of ship's autopilots and simulators, the availability of adequate mathematical models of the ship’s propulsion complex, which would describe with high accuracy the dynamics of the ship for the widest ranges of phase coordinates, plays a decisive role. Mathematical models of ship dynamics consist of mathematical models of inertial and non-inertial forces and moments on the ship's hull. The latter include hydrodynamic and aerodynamic forces and moments on the ship's hull, forces and moments caused by the operation of propellers, rigging, ship rudders. For the adequacy of the general mathematical model of the ship's dynamics, the adequacy of the mathematical models of all components of non-inertial forces and moments on the ship's hull is necessary. Mathematical models of non-inertial forces and moments on a ship's hull are usually empirical and made by processing data from experimental tests in ship model basin or in full-scale sea trials. In particular, this applies to the forces and moments caused by the operation of the propeller. In the mathematical modeling of the indicated forces and moments, the rectilinear movement of the vessel, or movement at small values of the drift angles, is usually considered. In this case, only the longitudinal action of the propeller is usually considered, and the transverse component of the force and the moment on the ship's propeller are unreasonably neglected. In addition, well-known mathematical models usually contain coefficients and functions that are difficult to determine using tables and graphs, which is inconvenient for numerical modeling. This work is intended to somewhat eliminate the indicated disadvantages. In particular, it was investigated how the curvilinear movement of the ship affects the operation of the propeller, analyzed the existing mathematical models, and new effective mathematical models of the longitudinal and transverse components of the force and moment caused by the operation of the ship's propeller in dimensional and dimensionless forms were proposed. In particular, representations are obtained for the dimensionless coefficients of the propeller stop and the moment on the propeller shaft, the wake fraction coefficient, the thrust-deduction factor, and skew of the flow on the propeller. It is shown how these parameters change for all possible values of the drift angle and angular velocity. For a number of commercial vessels of various types, technical characteristics are given, and parameters for constructing mathematical models of the dynamics of the propeller are calculated.

High-intensity curvilinear movements’ relevance in semi-professional soccer: An approach from principal components analysis

Due to the high number of variables reported from tracking systems, the interest in data reduction techniques has grown. To date, principal component analysis (PCA) has been performed in soccer, but since the results depend on the variables included, a lack of objectivity continues to be of concern. The aim of this study was to highlight the variables that compose the principal components (PC) in semi-professional soccer, including all variables extracted from tracking systems. Data were collected from a semi-professional Spanish team that participated in 10 matches. From more than 250 variables, the PCA grouped a total of 19 variables in six PCs, explaining 72% of players’ external load. All variables were related to centripetal force, high intensity running, and high-intensity efforts and short efforts. Interestingly, the first PC was composed of four variables related to centripetal force. The current exploratory analysis indicated that, in addition to traditional high-intensity displacement variables, force measures should also be considered in soccer match analysis due to their effect on a player’s external load.

Patterning candle soot for light-driven actuator via Marangoni effect

Smart light-driven machines that can be manipulated in a remote, contactless and controlled way are desired for many applications. Although considerable efforts have been devoted to the light-driven devices, challenges still remain in the multifunctional structure design, the development of patternable photothermal materials and precise control. In this report, we demonstrate a facile method to construct smart floating devices by the incorporation of candle soot with designable patterns into PDMS, which can be propelled by light-induced Marangoni effect. The device shows high photothermal conversion capability and photothermal stability. Meanwhile, it realizes multiple movement modes including linear, curvilinear movement and rotational movement by designing asymmetric structures or adjusting the illumination site of light sources. Moreover, the floating actuator can be driven not only by infrared (IR) light, but also by focused sunlight. This work will inspire us to explore great potentials in various fields such as soft robot, sensor, and electricity generator etc.