Optimal Modulation of Regenerative Braking in Through-The-Road Hybridized Vehicles

Regenerative braking can significantly improve the energy efficiency of hybrid and electric vehicles, and many studies have been carried out in order to improve and optimize the energy recovery of the braking energy. In the paper, the optimization of regenerative braking by means of braking force modulation is analysed, with specific application to the case of cars converted into Through-the-road (TTR) hybrid vehicles, and an optimal modulation strategy is also proposed. Car hybridization is an emerging topic since it may be a feasible, low-cost, intermediate step toward the green transition of the transport system with a potential positive impact in third-world countries. In this case, the presence of two in-wheel-motors installed on the rear axle and of the original mechanical braking system mounted on the vehicle can result in limited braking energy recovery in the absence of proper braking management strategies. A vehicle longitudinal model has been integrated with an algorithm of non-linear constrained optimization to maximize the energy recovery for various starting speed and stopping time, also considering the efficiency map and power limitations of the electric components. In the best conditions, the recovery can reach about 40% of the vehicle energy, selecting the best deceleration at each speed and proper modulation, and with a realistic estimate of the grip coefficient.

Match Acceleration and Deceleration Patterns in Female Collegiate Soccer Players

The purpose of the current investigation was to report acceleration and deceleration match data in female collegiate soccer players and compare between positions and game halves. A total of 24 players (11 defenders, five midfielders, and eight forwards) (age: M = 19.1, SD = 1.2 years; height: M = 1.64, SD = 0.05 m; and mass: M = 62.2, SD = 5.8 kg) underwent global positioning system monitoring and performance testing. Forwards covered significantly more distance per minute during high-intensity running (effect size [d]: 0.49) and sprinting (d = 0.64) when compared to midfielders across 16 matches for players logging 22.5 min per half. Significant and meaningful positional differences were determined with forwards covering the greatest average distance per acceleration efforts (d = 0.55) and initiating acceleration and deceleration efforts from a greater initial speed (ds = 0.57 and 0.69). When analyzing across all matches for players logging ≥ 40 min per half, second half decreases occurred in the number of accelerations (p < .001; d = 1.98) and decelerations (p < .001; d = 1.92), average distance of accelerations (p < .001; d = 0.83) and decelerations (p = .03; d = 1.30), and starting speed of accelerations (p = .01; d = 0.92) and decelerations (p = .04; d = 1.28). These results provide useful context when interpreting global positioning system–derived player-tracking metrics and can improve positional-specific training programs.

Level of speed abilities of young football players in various training periods

Purpose: At the highest level of the competition, the players tend to have a comprehensive motor, technical-tactical and mental preparation. It is assumed that in the training process of young players, speed is an important factor determining sports success. Therefore, the aim of the study was to try to compare the speed abilities indicator of young footballers during the summer and winter preparatory period. Material and methods: The research was conducted in July 2019 and January 2020 in Poznań. The research subject consisted of 23 young players of the Warta Poznań club in the age category of the junior football players (U14). Results: The results were statistically processed, basic descriptive characteristics were made, the normality of the distribution of differences was checked using the Shapiro-Wilk test, and the collected results from two tests dates were compared using the Student's t-test for dependent samples. Based on the the conducted research, no significant change in the starting speed level was observed at the distance of 5 meters and 15 meters, while an improvement in the level of speed abilities in terms of locomotion at the distance of 30 meters was noted. Conclusions. The level of running speed at a distance of 30 meters in the tested competitors changed in the six-month preparation cycle. There was no change in the starting speed level over the distance of 5 and 15 meters in the competition season between the preparatory period and the end of the autumn round in the competitors of the Poznań Warta club. On the basis of the conducted research, it is worth conducting experimental research based on individualized speed training on a group of 13 - 14 year old players.

Establishing patterns in the compatible electromagnetic and electromechanical transition processes when the starter is powered by a supercapacitor

Supercapacitors are commonly used for a guaranteed launch of diesel generators. However, the processes caused by the starting current until the starter shaft rotates are disregarded. The duration of this moment is short but its effect on the rechargeable battery, taking into consideration its service life, is significant. The shape of this pulse, its duration significantly depend on the ratio of system parameters: supercapacitor (rechargeable battery) – starter – diesel generator. A system of differential equations has been proposed to describe the compatible electromagnetic and electromechanical processes that occur when the starter of the diesel generator is powered from the supercapacitor. A charge is used as a variable quantity. The transitional processes occurring in the stationary starter rotor and the subsequent processes caused by the growth of the electromagnetic starter moment have been taken into consideration. This paper reports establishing those patterns that are related to the beginning of the starter movement, its entering the mode at the falling voltage of the supercapacitor, the exchange of electrical and magnetic energy accumulated in the inductive elements of the starter. Using the charge as a variable quantity has made it possible to combine the final values of the preceding process (stationary rotor) with the initial ones of the next one (output to starting speed). Thus, a mathematical notation has been derived that considers most of the parameters of the charge circle of the supercapacitor. The possibility of using an inflated voltage of the supercapacitor to increase the accumulated energy has been clarified. The processes have been theoretically substantiated, which makes it possible to use a small internal resistance of the starter circuit, the presence of inductive components, an abnormal capacity of the supercapacitor to form the desired shape of the electromagnetic moment. That would make it possible to take into consideration the specific requirements of various systems of guaranteed power supply.

Performance Characteristics of a Reciprocating Piston Pump Driven by a Wind Machine

The torque applied by a reciprocating pump on a wind machine axis is a fluctuating torque. The energy furnished by the pump on the wind machine axis is absorbed mainly in raising the water and the piston when the latter moves up. This has a direct adverse effect on the starting speed. The lower the maximum torque to be overcome, the easier will the wind machine start. If the necessary torque is high, a faster wind speed is required to start the wind machine. The operating time of the machine is consequently reduced. It is therefore desirable to reduce the starting torque, and hence to make the starting easier. This paper presents a theoretical study to reduce the starting torque of a non-conventional reciprocating piston pump by controlling the stroke volume of the pump or by controlling the flow rate of the piston pump. These two methods are the best to control, smooth and reduce the starting torque of the pump by drilling a very small hole in the piston. The effect of this hole is that at very low speed (at starting) all water that could be pumped is leaked through the hole. This is the main important of the hole which made the pressure on the piston is very low and as a result the starting torque is low. The quantity of water leaking through the hole is small compared to the normal output of the pump. Finally the comparison between normal and leakhole piston pump and the effect of this leakhole on the cavitation phenomena are studied

An analytical study comparing the work done and the instantaneous speed of the ball to launch the penalty skill from the penalty mark (6 meters and 10 meters) for FUTSAL players

The importance of the research lies in trying to find the best solutions to get the player to the optimal motor path by studying mechanical (kinematical) variables for one of the most important skills for the futsal soccer game, which is the scoring skill of the penalty marks (6 - 10) meters in highlighting the study of the differences between The completed work and the instantaneous speed of the ball to launch the scoring skill from the penalty mark for scoring (6 meters and 10 meters) for players in some biomechanical variables such as the vertical work done variable and the angle of the ball launch so that we can know those differences and overcome them in the stages of education and training. The research objectives were: 1-Knowing the values ​​of the job variables performed for the scoring skill from the penalty mark (6 meters - 10 meters) for FUTSAL players 2- Knowing the values ​​of the instant speed of the ball for scoring skill from the penalty mark (6 meters-10 meters) for FUTSAL players 3-Identify the differences between the work done and the instantaneous starting speed of the ball for scoring skill from the penalty mark (6 meters - 10 meters) for FUTSAL players The researcher used the descriptive method in the analysis method to suit his nature of the research. The research sample consisted of (12) players who represented the Sulaymaniyah Governorate team and the participant in the Iraqi championship for the first degree for the year (2016-2017). The researcher used video imaging to achieve the technical scientific observation by using a Japanese-made video camera (CASIO.EX.FH25.EXILM) with an internal memory (4kB) placed at a distance of (9.80 meters) and on the right of the player and the height of the lens ( 1,40) from the surface of the Earth, and the speed of the photographic machine was In video (120 images / second), the Kinovea V 0.8.24 program was used to obtain the vertical work variable and the starting angle of the sphere and the researcher used the following statistical methods (arithmetic mean - standard deviation - difference coefficient - T test for independent samples) To obtain the research data, the researcher recommended a set of recommendations and conclusions for the research.

Monitoring Cardiorespiratory Fitness in Professional Soccer Players: Is It Worth the Prick?

Purpose: To compare between-tests changes in submaximal exercise heart rate (HRex, 3 min, 12 km/h) and the speed associated with 4 mmol/L of blood lactate (V4mmol) in soccer players to get insight into their level of agreement and respective sensitivity to changes in players’ fitness. Methods: A total of 19 elite professional players (23 [3] y) performed 2 to 3 graded incremental treadmill tests (3-min stages interspersed with 1 min of passive recovery, starting speed 8 km/h, increment 2 km/h until exhaustion or 18 km/h if exhaustion was not reached before) over 1.5 seasons. The correlation between the changes in HRex and V4mmol was examined. Individual changes in the 2 variables were compared (>2 × typical error considered “clear”). Results: The changes in HRex and V4mmol were largely correlated (r = .82; 90% confidence interval, .65–.91). In more than 90% of the cases, when a clear individual change in HRex was observed, it was associated with a similar clear change in V4mmol (the same direction, improvement, or impairment of fitness) and conversely. Conclusions: When it comes to testing players submaximally, the present results suggest that practitioners can use HRex or V4mmol interchangeably with confidence. However, in comparison with a field-based standardized warm-up run (3–4 min, all players together), the value of a multistage incremental test with repeated blood lactate samplings is questionable for a monitoring purpose given its time, labor, cost, and poorer player buy-in.