Top Speed Research Articles

CERAMIC HIP RESURFACING ARTHROPLASTY SHOWS SIMILAR FUNCTIONAL GAIN TO METAL HIP RESURFACING ARTHROPLASTY

Reports of improved functional outcome of Metal on Metal Hip Resurfacing Arthroplasty (mHRA) to Total Hip Replacement needs to be balanced with concerns of metal ion release. By removing cobalt-chrome, cHRA reduces these risks. To the author's knowledge, there is no data available on functional outcomes of cHRA, therefore the aim of the study was to compare the function between cHRA patients and mHRA patients.24 patients received a unilateral cHRA (H1, Embody) and was compared to 24 age and gender matched patients with a unilateral mHRA (BHR, Smith and Nephew). All patients completed the Oxford Hip Score (OHS)[T2] and underwent gait analysis on an instrumented treadmill before and at a mean of 74wks (+/− 10) for mHRA and 53wks (+/− 2) for cHRA post op. Walking trials started at 4km/h and increased in 0.5km/h increments until a top walking speed (TWS) was achieved. Vertical ground reaction forces (GRF) were recorded along with the symmetry index (SI). Spatiotemporal measures of gait were also recorded. Vertical GRF were captured for the entire normalised stance phase using statistical parametric mapping (SPM; CI = 95%).The gain in OHS was similar: H1 (25-46), BHR(27-47). TWS increased by 19% with H1 (6.02 – 8.0km/hr), and 20% with BHR (6.02 – 7.37km/hr). SPM of the entire gait cycle illustrated the restoration of symmetry in both groups with no difference in GRF across the stance phase between groups at 5km/hr pre-op and post-op. At faster speeds (6.5km/hr), H1 patients had a mid-support GRF slightly closer to normal compared to BHR. Both groups increased step length similar from pre to post op (H1:0.76 – 0.85cm, BHR:0.77-0.86cm).In this study, subjective and objective functional outcome measures suggest that short term functional outcomes of ceramic resurfacing is not inferior to metal resurfacing.

Magnetic Microsphere Scaffold-Based Soft Microbots for Targeted Mesenchymal Stem Cell Delivery.

A soft microbot assembled from individual magnetic microsphere scaffold (MMS) beads carrying mesenchymal stem cells (MSC) is navigated under magnetic actuation, where an oscillating field induces mechanical flexion to propel the microbot toward the target site. A seven-bead microbot attained a top translational speed of 205.6µms-1 (0.068 body lengths-1 ) under 10mT and 2Hz field oscillation. The shallow flexion angle (10-24.5°) allows precision movements required to navigate narrow spaces. Upon arrival at the target site, the MMS beads unload their MSC cargo following exposure to a phosphate-buffered saline (PBS) solution, mimicking the extracellular fluid's sodium concentration. The released stem cells have excellent viability and vitality, promoting rapid healing (i.e., 83.2% vs 49%) in a scratch-wound assay. When paired with minimally invasive surgical methods, such as laparoscopy and endoscopic surgery, the microbot can provide precise stem cell delivery to hard-to-reach injury sites in the body to promote healing. Moreover, the microbot is designed to be highly versatile, with individual MMS beads customizable for cargoes of live cells, biomolecules, bionanomaterials, and pharmaceutical compounds for various therapeutic requirements.

Influence of hydrogen fuel cell temperature safety on bus driving characteristics and stack heating mode

Hydrogen fuel cells have developed rapidly in bus because of their cleanliness. The driving parameters of hydrogen fuel cell bus and the internal temperature distribution of hydrogen fuel stack are investigated in this study. The 1-D model of hydrogen fuel cell bus and the 2-D model of hydrogen fuel cell stack are established based on AMESim. In the cooling process, for the existing typical thermal management system, the influence of ambient temperature on the fuel cell bus driving parameters is analyzed by the 1-D model. In the heating process, the internal temperature distribution of the stack is analyzed under three heating modes by the 2-D model. As the ambient temperature increases, to ensure the safe operating temperature of the fuel cells, the bus top speed should be reduced, and the acceleration time should be extended. When the stack needs to be heated, the gas-liquid heating mode can supply a more uniform temperature distribution inside the stack. • The 1-D vehicle model and 2-D stack model of hydrogen fuel cell are established. • The effect of ambient temperature on driving parameters is analyzed. • The internal temperature distribution of the stack is analyzed under three heating modes. • Gas-liquid heating mode can give a more uniform stack temperature distribution.

Statistical Approach for Electric Taxiing Requirements for Regional Turboprop Aircraft

Electric motorization of landing gear appears to be one of the alternative solutions to reduce fuel burn, carbon dioxide emissions, and noise during the taxi phase. Because turboprop aircraft operate on short routes, the taxi phase represents an important part of both flight time and fuel consumption. An electric taxiing system (ETS) sized to meet current operational practices could reduce the fuel consumption and remain nearly transparent to the pilots. This paper first presents a statistical approach to define the taxiing requirements for regional turboprop aircraft using 200 taxi phases of 77 aircraft. Requirements of maximum acceleration until 15 kt, a 25 kt top speed, and a 13,000 ft distance (including taxi-in and taxi-out) are determined in accordance with the analysis, operational practices, and pilots’ routines. For a speed higher than 15 kt, the acceleration requirement is adjusted using the isopower to limit the mass of the ETS. Then, an ETS with sufficient performance is sized to be integrated in the main landing gear of a regional turboprop aircraft (Dash 8-300). For a standard mission of 270 nautical miles, the expected fuel economy is 3.1% for a payload loss of 2.2% or 1.3 passengers due to the system weight.

Statistical Analysis of the Interdependence between the Technical and Functional Parameters of Electric Vehicles in the European Market

The vehicle market at the European level (and also elsewhere) has registered a high dynamic for the adoption of electric vehicles as the future means of transport. Government policies and decisions fully support this move, but there are still massive barriers to entry into the EV market due to consumer attitudes and perceptions. Consumer attitudes and perceptions will be decisive in the market success of future electric vehicle models, given that consumers are particularly interested in the vehicles’ technical and dynamic performance. The pressure from customers’ demands for performance leaves its mark not only on the increase of performance and technical parameters, but directly contributes to the generation of interdependence between these parameters. This article presents a comparative statistical analysis of 203 electric vehicle models (from various construction categories), present in the European vehicle market (between the years 2019 and 2022), to highlight the direct and indirect links (interdependencies) between technical and performance parameters depending on the constructive class (type). The goal of this article is to determine whether there is a relationship between the three key performance metrics for electric vehicles—autonomy, top speed, and acceleration—and five significant technical/constructive metrics for these vehicles—battery capacity, energy efficiency, electric motor power, fast charging speed, and vehicle weight (brand and year of availability in the market). Based on the analyzed data, it can be stated that the design and construction of an electric vehicle model currently takes into account both performance and technical parameters, with a strong link between the weight of the vehicle and the energy capacity of the battery (+0.687) being highlighted and also the relationship between autonomy and vehicle weight (+0.355). The conclusions of this study can be used in the future by manufacturers for the development of new models of electric vehicles (new generic platforms and chassis) by classifying/standardizing these vehicles into specific classes, corresponding to the requirements of different classes of consumers or identifying constructive solutions specific to each type of consumer.

Special issue on all‐electric and hybrid‐electric flight

Special issue on all‐electric and hybrid‐electric flight

The contributing external load factors to internal load during small-sided games in professional rugby union players.

This study aimed to investigate which external load variables were associated with internal load during three small-sided games (SSG) in professional rugby union players. Forty professional rugby union players (22 forwards, 18 backs) competing in the English Gallagher Premiership were recruited. Three different SSGs were designed: one for backs, one for forwards, and one for both backs and forwards. General linear mixed-effects models were implemented with internal load as dependent variable quantified using Stagno's training impulse, and external load as independent variables quantified using total distance, high-speed (>61% top speed) running distance, average acceleration-deceleration, PlayerLoad™, PlayerLoad™ slow (<2 m·s-1), number of get-ups, number of first-man-to-ruck. Internal load was associated with different external load variables dependent on SSG design. When backs and forwards were included in the same SSG, internal load differed between positional groups (MLE = -121.94, SE = 29.03, t = -4.20). Based on the SSGs investigated, practitioners should manipulate different constraints to elicit a certain internal load in their players based on the specific SSG design. Furthermore, the potential effect of playing position on internal load should be taken into account in the process of SSG design when both backs and forwards are included.

Analysis of walking speeds and success rates on mid-block crossings using virtual reality simulation

A focus is set worldwide to study pedestrian behavior in road situations associated with a high frequency of crashes. This paper presents the results from a virtual reality simulation study that recorded pedestrians performing mid-block crossings on a straight segment of an urban street. The experiment was designed with eight scenarios with combinations of one or two lanes, two vehicle speeds, and constant or variable gaps between vehicles. The experiment was conducted with 48 subjects producing 538 crossing observations. The results show that subjects, on average, watched about 5 vehicle gaps in traffic before crossing the street and accepted a gap of 4.5 s between vehicles to cross. A regression model showed that the vehicle speed, the number of lanes, and subjects in the 66–85 years old group had a significant effect on the gap value accepted to cross. An interaction term based on gender and number of lanes also had a significant effect on the accepted gap. The study found average walking speeds between 4.1 and 4.8 ft/s (1.2–1.4 m/s) for different scenarios. A regression model revealed that the gender, the number of lanes, and the gap accepted to cross influenced the walking speed. Significant effects of interactions of the age with gender, number of lanes, and vehicle speed variables were also found that explain the differences in walking speed. The results for the success rate when crossing the street showed the overall worst performance in the scenario with traffic generated with a 25-mph (40 km/h) speed and a constant 3-s gap between vehicles. A Logit model showed that the probability of a pedestrian being hit by a vehicle increased with age, with traffic at the top vehicle speed, and with the constant 3-s vehicle gap. In contrast, the probability decreased with increases in the vehicle gap accepted to cross and the walking speed.

Numerical simulation and verification of rotor downwash flow field of plant protection UAV at different rotor speeds.

In aerial spraying of plant protection UAVs, the continuous reduction of pesticides is an objective process. Under the condition of constant flight state (speed and altitude), the change of pesticide loading will inevitably lead to the shift of lift force and rotor speed generated by UAV rotor rotation, which will change the distribution of the rotor flow field and affect the effect of aerial spraying operation of plant protection UAV. Therefore, the rotor speed of UAV is taken as the research object in this paper, and the adaptive refinement physical model based on the Lattice Boltzmann Method (LBM) is used to numerically simulate the rotor flow field of the quadrotor plant-protection UAV at different speeds. A high-speed particle image velocimeter (PIV) was used to obtain and verify the motion state of the droplets emitted from the fan nozzle in the rotor flow field at different speeds. The results show that, with the increase of rotor speed, the maximum velocity and vorticity of the wind field under the rotor increase gradually, the top wind speed can reach 13m/s, and the maximum vorticity can reach 589.64s -1. Moreover, the maximum velocity flow value is mainly concentrated within 1m below the rotor, and the maximum vorticity value is primarily concentrated within 0.5m. However, with the increase of time, the ultimate value of velocity and vorticity decreases due to the appearance of turbulence, and the distribution of velocity and vorticity are symmetrically distributed along the centre line of the fuselage, within the range of (-1m, 1m) in the X direction. It is consistent with the motion state of droplets under the action of the rotor downwash flow field obtained by PIV. The study results are expected to reveal and understand the change law of the rotor flow field of plant protection UAVs with the dynamic change of pesticide loading to provide a theoretical basis for the development of precise spraying operation mode of plant protection UAVs and improve the operation effect.

Athlete External Loads Across a Collegiate Men's Lacrosse Season.

Fields, JB, Jones, MT, Feit, MK, and Jagim, AR. Athlete external loads across a collegiate men's lacrosse season. J Strength Cond Res 37(8): e455-e461, 2023-Tracking and quantifying athlete workload may provide insight into best practice periodization strategies and workload management. Limited information exists detailing the external demands associated with collegiate men's lacrosse. Therefore, the purpose of this study was to investigate and compare practice, game, and positional differences across a lacrosse season. Male collegiate lacrosse athletes ( n = 17; body mass: 79.9 kg ± 9.7 kg; body fat %: 14.7 ± 3.8%) wore a global positional system device during practices ( n = 66) and games ( n = 19). External load metrics were total distance (TD), sprint distance (SD), accelerations (>3 m·s -2 ), sprint efforts, player load (PL), PL/min, and top speed. Multiple analysis of variances assessed differences in external loads across session (practice versus game) and sport position (attackers, midfielders, and defenders). A 3 × 4 analysis of variance was used to determine a position-by-time (first quarter [Q1], second quarter [Q2], third quarter [Q3], and fourth quarter [Q4]) interaction ( p < 0.05). Total distance ( p < 0.001, η2 : 0.047), SD ( p < 0.001, η2 : 0.093), sprint efforts ( p < 0.001, η2 : 0.077), PL ( p < 0.001, η2 : 0.022), and top speeds ( p < 0.001, η2 : 0.086) were all higher in games compared with practices. Attackers and defenders covered more TD ( p < 0.001, η2 = 0.0257), accelerations ( p < 0.001, η2 = 0.126), PL ( p < 0.001, η2 = 0.233), and PL/min ( p < 0.001, η2 = 0.193) than midfielders. Attackers and midfielders covered more SD ( p = 0.002 η2 = 0.043), sprint efforts ( p < 0.001, η2 = 0.053), and achieved higher top speed ( p < 0.001, η2 = 0.0063) than defenders. Volume and intensity metrics declined by Q4 in attackers and defenders ( p < 0.05), whereas external load measures did not differ across quarters for midfielders. Monitoring in-game external loads can assist coaches with individualizing training programs and preparing athletes for game demands.

Playing Disability Rugby League with Charcot-Marie-Tooth Disease: A Case Study

Charcot-Marie-Tooth (CMT) disease is a common inherited neurological disorder that causes damage to peripheral nerves. Reports of CMT patients participating in team-based sports such as disability rugby league are scarce. The objective of this case report was to evaluate the benefits of participation in disability rugby league in a 50-year-old male with CMT. Leg muscle mass and strength was worse for the case subject compared to two age-matched CMT participants with an exercise history; however, evidence of greater function in the case subject was observed through better 6-min walk test performance. Performance in a series of sport specific tests was noticeably worse for the case subject compared to a fellow rugby league player (age matched) with cerebral palsy. Inferior in-game performance was observed for the case subject compared to his fellow rugby league player in terms of distance covered, top running speed, and intensity. However, the case subject may have assumed a different role when playing as evident by the different behaviours he displayed during the games (i.e., less player contacts, tackles, or touches, but more passes of the ball). This case study provides information concerning disability rugby league as an adjunctive mode of treatment for CMT populations.

Relationships Between Sprint, Acceleration, and Deceleration Metrics with Training Load in Division I Collegiate Women's Soccer Players.

Player load is a variable derived from GPS technology that quantifies external load demands. Sprints and change-of-direction movements are high-intensity activities that place stress on the body. Research is needed to determine which sprint metrics may relate to and predict player load during practice sessions in collegiate women's soccer players, as coaches could manipulate the most impactful variables. This study analyzed which sprint metrics related to GPS player load in women's soccer players from one Division I team. Data from 19 practice sessions for 18 field players were analyzed. Players wore GPS sensors during all training sessions, and the variables assessed were player load, sprint count, sprint volume, sprint distance, average top speed, maximum top speed, and the number of accelerations and decelerations in different speed zones (±1, ±2, ±3, ±4, ±5 m/s2). Pearson's correlations (p < 0.05) analyzed relationships between the sprint variables and player load. Stepwise regression analyses (p < 0.05) determined if any metrics predicted player load. The results indicated significant relationships between player load and sprint count, maximum top speed, sprint distance, sprint volume, number of decelerations at -1, -2, and -3 m/s2, and accelerations at 1, 2, and 5 m/s2(r = 0.512-0.861, p ≤ 0.025). Sprint distance and decelerations at 1 m/s2predicted player load (p = 0.001, r2= 0.867). Maximal sprinting and decelerations and accelerations at different speeds were significant contributors to player load in collegiate women's soccer players. Sprint distance, decelerations, and accelerations could be targeted in training drills via dimension and movement manipulation to adjust training intensity for collegiate women's soccer players.

Relationships between external loads, sRPE-load, and self-reported soreness across a men's collegiate soccer season.

The purpose was to examine relationships between external loads (ELs), perceived exertion, and soreness. Collegiate men soccer players (n = 19) were monitored for 72 sessions (training: n = 53; matches: n = 19). Likert scale assessments (0-6) of lower body soreness were collected prior to each session, and ELs were collected using positional monitoring technology. Session rate of perceived exertion (sRPE-load) was calculated by multiplying perceived exertion values (Borg CR-10 Scale) by respective session duration to determine internal load. Multiple analyses of variance were used to determine differences in ELs across seasons (pre-season, in-season, post-season) and sessions (training, match). Bivariate Pearson correlation coefficients and linear regression analyses were used to evaluate relationships among soreness, ELs, and sRPE-load. Greatest ELs were observed during pre-season and post-season phases (p < 0.001). Sessions with high perceived exertion and low soreness were associated with higher ELs (p < 0.05). Duration (t = 16.13), total distance (t = 9.17), sprint distance (t = 7.54), player load (t = 4.22), top speed (t = 4.69), and acceleration (t = 2.02) positively predicted sRPE-load (F = 412.9, p < 0.001, R2 = 0.75). Soreness was weakly and trivially correlated with ELs (p < 0.05). The very strong relationship between ELs and sRPE-load highlights the utility of sRPE-load as a practical means to estimate workload; however, more research into the relationship between soreness and workload is warranted.

Relationship between vertical jump tests and ice-skating performance in junior Polish ice hockey players

The aim of this study was to determine the relationships between vertical jumps (VJ) and various on-ice skating performances of junior ice hockey players (n = 19). The three modes of VJ or off-ice measures were countermovement jump with arm swing (CMJ), squat jump (SJ) and depth drop jump (DDJ). The on-ice skating performance was measured by the skating multistage aerobic test (SMAT), forward and backward acceleration test, top speed test, and repeated sprint ability (RSA) test. The relationships between the variables were quantified using Pearson's product-moment correlation. DDJ showed a significant positive correlation with forward average skating speed (FASS) (r = 0.62) and strong correlations with backward average skating speed (BASS) (r = 0.81), and maximum skating speed (MSS) (r = 0.71). SJ was found to be strongly correlated with BASS (r = 0.82) and MSS (r = 0.76), whereas the only on-ice performance that significantly correlated with CMJ was BASS (r = 0.68). All three modes of VJ were inversely and non-significantly correlated with performance decrement index and fatigue index, as determined by the RSA test. SMAT was not significantly correlated with either VJ or RSA. Correlations between all three modes of VJ tests were significant. Therefore, this study concludes that: (1) DDJ can be used as a predictor of all the ice skating speed tests, whereas SJ can predict BASS and MSS. CMJ, on the other hand, can predict the performance of only BASS. (2) RSA performance cannot be predicted from CMJ, SJ, or DDJ tests, and (3) neither any of the VJ nor RSA can predict skating endurance of junior ice hockey players.

A Tube-MPC Approach to Autonomous Multi-Vehicle Racing on High-Speed Ovals

Autonomous vehicle racing has emerged as vibrant, innovative technology development, demonstration platform in recent years. Universities, companies demonstrate their achievements on various vehicles - from 1:10th to full-scale prototypes. One of those platforms is the Dallara AV-21, and the spec-vehicle for the Indy Autonomous Challenge. This paper outlines the robust model predictive control (MPC) concept used within the software stack of the TUM Autonomous Motorsport team. It is based on a simplified friction-limited point mass model and a set of low-level feedback controllers. The remaining model uncertainties are managed via introducing a constraint-tightening approach based on a Tube-MPC approach. In contrast to classical tracking controllers, the optimization problem is formulated to freely optimize the trajectory while staying within certain maximum deviations of the reference. This approach allows to rely on a coarse output of the trajectory planning approach while maintaining smoothness requirements in steering, throttle, and brake actuation. The paper highlights the advantages of the proposed robust reoptimization concept compared to pure tracking formulations. It showcases the performance compared to a classical LQR controller and an MPC, which utilizes a vehicle model with a more sophisticated tire model. The controller achieved a top speed of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{265 kmh}^{-1}$</tex-math></inline-formula> and lateral accelerations up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\text{21 ms}}^{-2}$</tex-math></inline-formula> during a two-vehicle competition involving dynamic overtaking maneuvers on the Las Vegas Motor Speedway, a famous racetrack with turns banked up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$20^{\circ }$</tex-math></inline-formula> .

Effect of Changing Primary Fixed Sheave Angle and Roller Weight on Torque, Power, Top Speed, and Acceleration on Matic Motorcycles

This study aimed to determine the effect of angle changes on the primary fixed sheave and roller mass on torque, acceleration, engine power, and top speed of automatic motorcycles. This type of research is experimental research. The subjects in this study were 125 cc automatic motorcycles modified at the angle of the primary fixed sheave and the mass of the rollers. The angles of change were 14.5˚, 13.5˚, and 12.5˚; while the change in roller mass was 14, 13, and 12 grams. The testing began with tuning up the motorbike, then installing the fixed sheave and roller primary units that have been modified to the CVT (Continuously Variable Transmission) primary drive for further testing, and collecting the data using a dyno test tool. The results of this study show that: 1) Changes made to the primary drive pulley, especially to changes in the angle of the Primary fixed sheave and the weight or mass of the roller with the application simultaneously affect the torque, acceleration, engine power, and top speed of automatic motorbikes; 2) changing the angle of the primary fixed sheave (13.5˚) with the application of a roller weight of 13 grams can increase the maximum speed (top speed) by 0.4 (Kph) compared to the standard ones; 3) the increase in power and torque resulting from changes in the primary fixed sheave and the weight of the rollers applied at the same time do not significantly increase top speed and acceleration. Conversely, low power and torque do not necessarily reduce the top speed and acceleration of automatic motorcycles.

Comparison among U-17, U-20, and Professional Female Soccer in the GPS Profiles during Brazilian Championships

The purpose of this study was to compare and characterize the physical demand of official matches among under-17 (U-17), under-20 (U-20), and professional (Pro) female soccer players. All matches were from the U-17, U-20, and Pro National Brazilian Championships. Fourteen Pro matches, nine U-20 matches, and four U-17 matches were analyzed. The external load was measured by the global positioning system (GPS) and the internal workload was assessed by the ratings of perceived exertion (RPE) multiplied by the duration of the match. The activity profiles measured were total distance covered (km), total sprint distance (m) (speed > 18 km·h-1), number of accelerations and decelerations (between 1 and 2 m·s-2 and >3 m·s-2), and top speed (km·h-1). For the analysis, we standardized all the metrics (except the top speed) by the time (in minutes) played. The Pro group presented higher sprint distances, number of accelerations and decelerations, and top speeds, compared to U-20 and U-17. There was no difference in the total distance among groups, and there was no difference in any GPS metrics between U-20 and U-17. The RPE was higher in Pro and U-17, compared to U-20; however, the workload-RPE was higher in Pro, compared to both U-17 and U-20 groups. These findings provide important information for the evolution of physical performance according to age categories in elite female soccer players.

Racing Towards a Faster Tomorrow

There&apos;s a technology revolution happening that will transform the speed at which we will travel. E&amp;T looks at five ways you could get there faster in the future. Hyperloop- a system based on tracked tubes and terminals, with pods moving free from air resistance by magnetic propulsion, theoretically transport people and goods at a speed of 700mph. Boom Overture - a supersonic transport airliner that will be built from composite materials, powered by non-afterburning turbo fans, and run entirely on sustainable aviation fuel. Electric vehicles- companies like Tesla develop vehicles such as the Model S, capable of getting from 0-60mph in 1.99 seconds and a top speed of 200mph. Circular runways- a revolutionary runway design that could save fuel costs, promote airport efficiency, save space and reduce taxi time. Maglev- high-speed rail based on magnetic levitation technology.

QUaRTM: A Quadcopter with Unactuated Rotor Tilting Mechanism capable of faster, more agile, and more efficient flight.

We present QUaRTM - a novel quadcopter design capable of tilting the propellers into the forward flight direction, which reduces the drag area and therefore allows for faster, more agile, and more efficient flight. The vehicle can morph between two configurations in mid-air, including the untilted configuration and the tilted configuration. The vehicle in the untilted configuration has a higher pitch torque capacity and a smaller vertical dimension. The vehicle in the tilted configuration has a lower drag area, leading to a higher top speed, higher agility at high speed, and better flight efficiency. The morphing is accomplished without any additional actuators beyond the four motors of a quadcopter. The rigid connections between the quadcopter frame and the quadcopter arms are replaced with sprung hinges. This allows the propellers to be tilted when high thrusts are produced, and recover to the untilted configuration when the thrusts are brought low. The effectiveness of such a vehicle is demonstrated by running experiments on a prototype vehicle with a shape similar to a regular quadcopter. Through the use of tilting, the vehicle is shown to have a 12.5% higher maximum speed, better high-speed agility as the maximum crash-free cruise speed increased by 7.5%, and a better flight efficiency as the power consumption has dropped by more than 20% in the speed range of 15-20ms-1.

IDENTIFIKASI PANJANG LANGKAH DAN FREKUENSI LANGKAH SEBAGAI FAKTOR PENENTU KECEPATAN LARI SPRINT 100 M

This study aims to identify the variability of stride length and stride frequency of junior-level 100 m sprinters with different performance levels and to verify the kinematics parameters of the phases of sprinting. Data were collected from a sample of 9 junior sprinter athletes determined by purposeful sampling. The analysis results show that the average number of steps for 100 m is 52.8. For the variable stride length, the average is 1.88 m. The step frequency variable shows an average of 4.77 steps/second (max step frequency). During the acceleration phase, the average stride frequency is 4.48 steps/second. The score in the last phase, i.e., the sprinters must maintain their velocity until the end of the race from a distance of 60 – 100 m, shows an average rate of 4.07 steps/second. The average sprinting time of the sprinters is 11.74 seconds, and the average speed of the sprinters is 8.54 ms-1, with a top speed of 8.95 ms-1 and the lowest speed of 7.99 ms-1. Based on the analysis of kinematic parameters, the different phase structures. The results show that stride length significantly contributes to the 100 m sprint performance than stride frequency, which is no longer considered the most critical determinant of performance at junior-level athletes.