Average Deceleration Research Articles

Bicycle Braking Performance Testing and Analysis

<div class="section abstract"><div class="htmlview paragraph">The goal of this study was to determine bicycle braking performance, while considering different brake designs and applications. Eight bicycles were used to perform brake-to-stop tests: two full suspension mountain bikes, two hybrid bikes, one beach cruiser, one BMX bike, one road bike, and one single speed bicycle. The standardized brake testing procedure consisted of rear only brake application and both front and rear brake application. In order to maintain brake application consistency, a single rider performed all series of the brake tests at the same location, within a designated brake zone on dry asphalt. The tests were performed at initial velocities of 11 to 21 mph. For each test, the rider accelerated to the test speed and, upon entering the brake zone, applied maximum braking effort while maintaining a natural upright position in order to minimize lean. The associated skid marks deposited from wheel lock-up were verified, measured, and documented onsite. Bicycle wheel lock-up was verified if needed via video analysis. The bicycles’ deceleration rates were measured with a Midé Slam Stick X accelerometer, VBOX Sport, and calculated from the deposited skid marks. The deceleration rates measured using the Slam Stick X ranged between 0.40 - 0.71 g for front and rear brake application and 0.25 - 0.37 g for rear only brake application, across all bicycle types. Bicycles with rear coaster brake setups, such as the beach cruiser, braked at an average deceleration rate of 0.25 - 0.36 g. Bicycles with caliper and disc brake setups exhibited an average deceleration rate range of 0.27 - 0.36 g for rear only brake application. Additionally, the incipient lock-up phase was analyzed for distance travelled, speed change, duration, and kinetic energy loss.</div></div>

A Base Study to Investigate MASH Conservativeness of Occupant Risk Evaluation

Abstract The manual for assessing safety hardware (MASH) defines crash tests to assess the impact performance of highway safety features in frontal and oblique impact events. Within MASH, the risk of injury to the occupant is assessed based on a “flail-space” model that estimates the average deceleration that an unrestrained occupant would experience when contacting the vehicle interior in a MASH crash test and uses the parameter as a surrogate for injury risk. MASH occupant risk criteria, however, are considered conservative in their nature, due to the fact that they are based on unrestrained occupant accelerations. Therefore, there is potential for increasing the maximum limits dictated in MASH for occupant risk evaluation. A frontal full-scale vehicle impact was performed with inclusion of an instrumented anthropomorphic test device (ATD). The scope of this study was to investigate the performance of the flail space model (FSM) in a full-scale crash test compared to the instrumented ATD recorded forces which can more accurately predict the occupant response during a collision event. Additionally, a finite element (FE) model was developed and calibrated against the full-scale crash test. The calibrated model can be used to perform parametric simulations with different testing conditions. Results obtained through this research will be considered for better correlation between vehicle accelerations and occupant injury. This becomes extremely important for designing and evaluating barrier systems that must fit within geometrical site constraints, which do not provide adequate length to redirect test vehicles according to MASH conservative evaluation criteria.

Vehicle Fuel Consumption Prediction Method Based on Driving Behavior Data Collected from Smartphones

Transportation is an important factor that affects energy consumption, and driving behavior is one of the main factors affecting vehicle fuel consumption. The purpose of this paper is to improve fuel consumption monitoring databases based on mobile phone data. Based on the mobile phone terminals and on-board diagnostic system (OBD) installed in taxis, driving behavior data and fuel consumption data are extracted, respectively. By matching the driving behavior data collected by a mobile phone with the fuel consumption data collected by OBD, the correlation between driving behavior and fuel consumption is explored, so that vehicle fuel consumption could be predicted based on mobile phone data. The fuel consumption prediction models are built using back propagation (BP) neural network, support vector regression (SVR), and random forests. The results show that the average speed, average speed except for idle (ASEI), average acceleration, average deceleration, acceleration time percentage, deceleration time percentage, and cruising time percentage are important indicators for fuel consumption evaluation. All three models could predict fuel consumption accurately, with an absolute relative error less than 10%. The random forest model is proved to have the highest accuracy and runs faster, making it suitable for wide application. This method lays a foundation for monitoring database improvement and fine management of urban transportation fuel consumption.

A rail transit simulation system for multi-modal energy-efficient routing applications

The paper develops a continuous rail transit simulator (RailSIM) intended for multi-modal energy-efficient routing applications. RailSIM integrates sophisticated train dynamics and energy models to replicate train motion and energy consumption behavior, respectively. The simulator is calibrated using an off-line optimization procedure to match preprogramed railway schedules by optimizing three model parameters, namely; the segment target speed, the average deceleration level, and the brake force adjustment factor. The objective of the calibration procedure is to match the simulated and actual average running speed for each station-to-station pair. Upon calibration, RailSIM is applied to the Greater Los Angeles area and validated at both the instantaneous and aggregated levels. Results demonstrate that RailSIM is able to produce realistic train dynamics and energy consumption estimates producing a comfortable ride while simultaneously matching the railway schedule. RailSIM is also demonstrated to capture the impact of track gradient on energy outputs. The results also indicate that a perfect match to empirical energy estimates is achieved at an average grade of 1.8%, which is a reasonable approximation of the average track gradient of the testing area. The sensitivity of RailSIM to some of the metro rail parameters is also discussed to account for its applicability to rail transit systems in other cities. Finally, a pilot test of RailSIM implementation in the higher-level multi-modal eco-routing system is performed to demonstrate RailSIM’s feasibility of supporting energy-efficient travel.

Decelerations of Passenger Vehicles on Gravel Arrester Beds

Gravel-filled arrester beds, also called safety-escape ramps or vehicle run-out areas, have long been a road-safety feature for safely stopping heavy road vehicles from running off the road. In the recent past, there has been consideration given to installing these features on highway access ramps to provide safe areas to stop passenger cars driving at highway speeds. The work presented in this article was performed to investigate the behaviour of standard-size passenger cars on gravel-filled arrester beds, with a particular focus on the achievable vehicle decelerations and the ability of the arrester beds to safely stop a passenger car coasting in an uncontrolled manner. The findings show that the achievable average decelerations are in the range of 0.3 g for coasting vehicles and up to 0.9 g when the vehicles are braking. The results prove that more research is required to quantify the influence of the gravel parameters on the achievable decelerations.

Variations in Naturalistic Driving Behavior and Visual Perception at the Entrances of Short, Medium, and Long Tunnels

Driver behavior and visual perception are very important factors in the management of traffic accident risk at tunnel entrances. This study was undertaken to analyze the differences in driving behavior and visual perception at the entrances of three types of tunnels, namely, short, medium-length, and long tunnels, under naturalistic driving conditions. Using three driving behavior indicators (speed, deceleration, and position) and two visual perception indicators (fixation and saccade), the driving performance of twenty drivers at six tunnels (two tunnels per condition) was comparatively analyzed. The results revealed that the speed maintained by the drivers prior to deceleration with braking under the short-tunnel condition was significantly larger than that under the medium- and long-tunnel conditions and that the drivers had a greater average and maximum deceleration rates under the short-tunnel condition. A similar general variation of driver visual perception appeared under the respective tunnel conditions, with the number of fixations gradually increasing and the maximum saccade amplitude gradually decreasing as the drivers approached the tunnel portal. However, the variation occurred approximately 60 m earlier under the short-tunnel condition than under the medium- and long-tunnel conditions. Interactive correlations between driving behavior and visual perception under the three conditions were established. The commencement of active deceleration was significantly associated (with correlation factors of 0.80, 0.77, and 0.79 under short-, medium-, and long-tunnel conditions, respectively) with the point at which the driver saccade amplitude fell below 10 degrees for more than 3 s. The results of this study add to the sum of knowledge of differential driver performance at the entrances of tunnels of different lengths.

Driving speed model development using driving data obtained from smartphone sensors

The aim of this paper is the development of driver speed models based on detailed driving data collected from smartphone sensors. More specifically, this research investigates to which extent various driving behaviour parameters (harsh acceleration and deceleration events, driving distance, percentage of driving time per different road types, etc.) interact with each other and how these might potentially serve as driving speed predictors. Real time driving behaviour data collection was carried out using a smartphone application. Data were collected from 100 drivers and a total of 18,853 trips between July and December 2016. Six different linear regression models are developed to predict average driving speed under different driving conditions. One model for each road type (urban, rural and highways), one model for the risky hours period and one for the rest of the day, and a general model. The results indicated that the distance covered by the driver, the number of the harsh events occurred and the average deceleration are the strongest predictors of the average speed of a driver.

Four-Wheel Electric Braking System Configuration With New Braking Torque Distribution Strategy for Improving Energy Recovery Efficiency

In this paper, a four-wheel electric braking system configuration is proposed for electric vehicles and its braking performance is compared with other conventional braking system configurations at different initial vehicle speeds and different road conditions in the case of emergency braking. In order to make the vehicle wheel slip ratio track the optimal slip ratio, a control method that combines sliding mode control and extended state observer is designed. Neural-network sliding mode control is designed for the driver’s braking command tracking in the normal braking condition. In order to improve braking energy recovery, a new braking torque distribution strategy is developed for the proposed four-wheel electric braking system based on the motor characteristics and vehicle dynamics. The designed braking torque distribution strategy is able to improve the energy recovery by adjusting the braking torque distribution ratio between the front and rear wheel braking torque while tracking the driver’s braking command. Numerical simulations have been conducted and the simulation results show that although the braking performance of the four-wheel electric braking system is worse than the conventional braking system at high initial braking speed, it still is able to meet the vehicle braking international standards and simplifies the braking system structure and saves cost. The proposed braking torque distribution strategy can improve energy recovery efficiency compared with the average allocation strategy and deceleration based allocation strategy. The simulation results show that the four-wheel electric braking system configuration with the proposed braking torque distribution strategy is suitable for low to medium speed light electric vehicles.

Driver-pedestrian interaction under legal and illegal pedestrian crossings

Pedestrian crossing outside of a zebra crossing (jaywalking) is one of those pedestrian behaviors that may highly affect safety and operations. Unlike permissible crossings at zebra crossings, jaywalking events are not often anticipated by drivers, which may result in less driver reaction time and different vehicle operation dynamics.The objective of the research was to study driver’s behavior as well as to model the interaction with a pedestrian, who was crossing at and outside (jaywalker) of designated zebra crossings. Data were collected through an instrumented vehicle study.Sixteen participants took part in the survey. Each participant’s vehicle was instrumented with a video camera and a global positioning system (GPS) device. Each participant drove his vehicle along two streets of the center of Rome, during which numerous events of crossings at and outside the zebra crossing were detected. The acquired data allowed obtaining the driver’s speed profiles in approach to the pedestrian crossing.The analysis was based on variables that were obtained from the speed profiles of drivers. The driver’s behavior under legal and illegal crossings was analyzed in terms of driver yielding rates and yielding types, relationship between speed and distance of the vehicle from the conflict point at the decision point, and for different times left for the vehicle to get to the conflict point at the moment the pedestrian reaches the curb as well as pedestrian origin (form the right or left).Significant differences were detected in driver’s behavior during the interaction with the pedestrian crossing at and outside of the zebra crossing. The main results highlighted that the average yield rate to jaywalkers was lower than that to pedestrians at permissible crossings, the average deceleration rates were higher in the case of illegal crossing and driver yielding decision point to jaywalkers was closer to the conflict point.The obtained results provide the basis for modeling interactions between pedestrians crossing at and outside of crosswalks and approaching drivers in a micro-simulation environment.

Intrapartum PRSA: a new method to predict fetal acidosis?-a case-control study.

Phase-rectified signal averaging method (PRSA) represents an analysis method which applied on fetal cardiotocography (CTG) allows the quantification of the speed of fetal heart rate changes. By calculating the average deceleration capacity (ADC) an assessment of the fetal autonomic nervous system (ANS) is possible. The objective of this study was to test its ability to predict perinatal acidosis. A case-control study was performed at a University Hospital in Munich. All intrapartum CTG heart rate tracings saved during a 7-year period were considered for analysis. All neonates born with an umbilical arterial blood pH ≤ 7.10 were considered as cases. Controls were defined as healthy fetuses born with a pH ≥ 7.25. The main matching criteria were gestational age at delivery, parity, birth mode, and birth weight percentile. Exclusion criteria were a planned caesarean section, fetal malformations, and multiple pregnancies. ADC and STV were then calculated during the last 60, the last 45, and the last 30min intervals prior to delivery. Of all stored birth CTG recordings, 227 cases met the inclusion criteria and were studied. ADC was significantly higher in fetuses born with acidemia (4.85bpm ± 3.0) compared to controls (3.36bpm ± 2.2). The area under ROC curve was 0.659 (95% CI 0.608-0.710) for ADC and 0.566 (0.512-0.620) for STV (p = 0.013). This study confirms that the assessment of ADC using PRSA represents a good additional tool for the prediction of acute fetal acidosis during delivery.

Determining indicators and criteria for functional stability of brake properties of cars

Problem. In the work, a study of urgent tasks that increase the technical level of vehicles and traffic safety by ensuring the functional stability of braking properties due to the development of methods for constructing the regulatory framework for its assessment is conducted. This article proposes indicators and criteria for the functional stability of the braking properties of vehicles, allowing to predict their deterioration during operation. As an example, an assessment of functional stability of the braking properties of category M1 cars is given. Goal. The aim of the study is to increase the technical level of vehicles and traffic safety by ensuring the functional stability of braking properties by developing methods for constructing a regulatory framework for its assessment. Methodology. Analytical methods are used to study indicators and criteria for the functional stability of the braking properties of vehicles, allowing to predict their deterioration during operation. Results. As an example, an assessment of the functional stability of braking properties of category M1 cars is given. Originality. To assess the braking properties of vehicles that are in operation, various standards should be used. For new cars, it is necessary to create a stock for the instability of steady deceleration, which is gradually spent during operation due to the deterioration of the technical condition. The definition of the functional stability of the braking properties of transport allowed us to propose a method for its assessment. The indicators of the average steady-state deceleration fall rate for the vehicle’s service life and the relative steady-state deceleration drop over the same period are proposed that can be used to normalize the stability of the braking properties of the vehicle. Practical value. The assessment of the minimum acceptable average steady-state decelerations regulated by state standards of Ukraine, using the proposed indicators, allowed us to determine that the vehicles of categories M1; N2 and N3 should have a stock for regulatory slowdowns ranging from 10% to 14%. For cars M2; M3 and N1 either the level of standard values for new cars must be increased, or the specified level for exchanges in operation should be lowered.

RANCANG BANGUN SISTEM REM MOBIL LISTRIK FUSENA

The brake system is a device to slow down or stop the movement of the wheel automatically so that the vehicle will move slowly. This completeness in the vehicle is very important and vital because it functions as a safety for life in driving. In the process of making the Electric Car Fusena brake system has steps in the process, consists of size planning, materials used, designs realized, manufacturing brake system supporting components, assembly, installation and testing of brake systems. The Fusena Electric Car brake system use a disc-type hydraulic brake system with one brake master that can work simultaneous with dual circuit fluids (front and rear braking). The comparison of the brake pedal is changed to 3: 1, designing and recreating the caliper stand to make it more precise so that it gets maximum brake performance and is better than the system used before. Static testing of the Fusena Electric Car hydraulic brake system is done by positioning the vehicle on an inclined plane at a slope of 15 and 20 with a variable driver load of 40 kg, 50 kg, 60 kg and 70 kg. The test results are that the vehicle does not experience displacement or movement. And the results of the average dynamic test of the Brake System at a speed of 27.3 km/h with an average braking distance of 171 cm = 1.71 meters and the average deceleration time is 0.26 seconds.

Design and Testing Impact Attenuator of Formula SAE FG17 Garuda UNY Car

This research aimed to find out the design and testing of Impact Attenuator (IA) on the Formula SAE FG17 Garuda UNY (as the development of learning materials in Materials Engineering course). The method used in this research is using research and development model (R & D). Product development model used ADIIE development model (Analysis, Design, Development, Implementation, and Evaluating). Based on the result of impact attenuator test with dimension length 220 mm, width 250 mm, height 250 mm and using 1 mm aluminum plate material in Abaqus software, it can be seen that the result of “Total Energy of The output set” on the test 7777724 mJ at 0.0325 s. Furthermore, based on the results of the impact attenuator test using UTM tool, capable of absorbing energy of 7722.25 Joule, Peak deceleration on impact attenuator specimens is 28.212 g’s, Average deceleration in this impact attenuator specimen is 15.908 g’s, The shape change on anti-intrusion plate test is 21.4 mm. From the test result, the Impact attenuator fulfills the 2017 Formula SAE (T3.20 Impact Attenuator) regulation.

Dynamics and wall collision of inertial particles in a solid–liquid turbulent channel flow

The dynamics and wall collision of inertial particles were investigated in non-isotropic turbulence of a horizontal liquid channel flow. The inertial particles were $125~\unicode[STIX]{x03BC}\text{m}$ glass beads at a volumetric concentration of 0.03 %. The bead-laden flow and the unladen base case had the same volumetric flow rates, with a shear Reynolds number, $Re_{\unicode[STIX]{x1D70F}}$, of the unladen flow equal to 410 based on the half-channel height and friction velocity. Lagrangian measurements of three-dimensional trajectories of both fluid tracers and glass beads were obtained using time-resolved particle tracking velocimetry based on the shake-the-box algorithm of Schanz et al. (Exp. Fluids, vol. 57, no. 5, 2016, pp. 1–27). The analysis showed that on average the near-wall glass beads decelerate in the streamwise direction, while farther away from the wall, the streamwise acceleration of the glass beads became positive. The ejection motions provided a local maximum streamwise acceleration above the buffer layer by transporting glass beads to high velocity layers and exposing them to a high drag force in the streamwise direction. Conversely, the sweep motion made the maximum contribution to the average streamwise deceleration of glass beads in the near-wall region. The wall-normal acceleration of the beads was positive in the vicinity of the wall, and it became negative farther from the wall. The investigation showed that the glass beads with sweeping motion had the maximum momentum, streamwise deceleration, and wall-normal acceleration among all the beads close to the wall and these values increased with increasing their trajectory angle. The investigation of the beads that collided with the wall showed that those with shallow impact angles (less than $1.5^{\circ }$) typically slide along the wall. The sliding beads had a small streamwise momentum exchange of ${\sim}5\,\%$ during these events. The duration of their sliding motion could be as much as five times the inner time scale of the unladen flow. The wall-normal velocity of these beads after sliding was greater than their wall-normal velocity before sliding, and was associated with the rotation induced lift force. Beads with impact angles greater than $1.5^{\circ }$ had shorter interaction times with the wall and smaller streamwise and wall-normal restitution ratios.

Physical Performance Differences Between Starter and Non-Starter Players During Professional Soccer Friendly Matches.

The aim of this study was to investigate the physical performance differences between players that started (i.e. starters, ≥65 minutes played) and those that were substituted into (i.e. non‐starter) soccer friendly matches. Fourteen professional players (age: 23.2 ± 2.7 years, body height: 178 ± 6 cm, body mass: 73.2 ± 6.9 kg) took part in this study. Twenty, physical performance‐related match variables (e.g. distance covered at different intensities, accelerations and decelerations, player load, maximal running speed, exertion index, work‐to‐rest ratio and rating of perceived exertion) were collected during two matches. Results were analysed using effect sizes (ES) and magnitude based inferences. Compared to starters, non‐starters covered greater match distance within the following intensity categories: >3.3≤4.2m/s (very likely), >4.2≤5 m/s (likely) and >5≤6.9 m/s (likely). In contrast, similar match average acceleration and deceleration values were identified for starters and non‐starters (trivial). Indicators of workloads including player loads (very likely), the exertion index (very likely), and the work–to‐rest ratio (very likely) were greater, while self‐ reported ratings of perceived exertion were lower (likely) for non‐starters compared to starters. The current study demonstrates that substantial physical performance differences during friendly soccer matches exist between starters and non‐starters. Identification of these differences enables coaches and analysts to potentially prescribe optimal training loads and microcycles based upon player’s match starting status.

Theoretical Value of Deceleration Capacity Points to Deceleration Reserve of Fetal Heart Rate.

The interpretation of Average Acceleration and Deceleration Capacities (AC/DC), computed through Phase-Rectified Signal Averaging (PRSA), in intrapartum fetal heart rate (FHR) monitoring is still matter of investigation. We aimed to elucidate some behaviors of AC/DC. We derived the theoretical value of PRSA for stationary stochastic Gaussian processes and proved that for these time series AC and DC are necessarily identical in absolute value. The difference between DC and AC, termed Deceleration Reserve (DR), was introduced to detect signal's asymmetric trends. DR was tested on FHR signals from: near-term pregnant sheep model of labor consisting of chronically hypoxic and normoxic fetuses with both groups developing acidemia due to umbilical cord occlusions (UCO); and the CTU-UHB dataset containing fetal CTG recordings collected during labor of newborns that resulted acidotic and non-acidotic, respectively. DR was compared with AC and DC in terms of discriminatory power (AUC), between the groups, after correcting for signal power or deceleration area, respectively. DR displayed higher discriminatory power on the animal model during severe acidemia, with respect to AC/DC ( ) but also distinguished correctly all chronically hypoxic from normoxic fetuses at baseline prior to UCO. DR also outperformed AC/DC on the CTU-UHB dataset in distinguishing acidemic fetuses at birth (AUC: 0.65). Theoretical results motivated the introduction of DR, that proved to be superior than AC/DC for risk stratification during labor. DR, measured during labor, might permit to distinguish acidemic fetuses due to their different autonomic regulation, paving the way for new monitoring strategies.

Assessment Of Functional Baseline And Return To Play Criteria Using Gps Profile

Objectives:Return to play (RTP) are high following lower extremity injuries; however, objective sport specific clearance criteria are lacking. In ACL rehabilitation for example, current tests that are used such as single leg hop, isokinetic testing, and quad strength are not sport specific and do not take fatigue into account. With the development of wearable GPS technologies (Catapult), there is great potential for the creation of objective RTP criteria. These GPS units provide objective validated data points in regards to athletes and their movements during games, training, or rehabilitation. It is reported over 1,500 teams across 35 sports, including NFL, NBA, MLB, and NCAA, are now using this technology. Teams have a vast amount of information, however, it is largely underutilized by the medical staff, and no standardized benchmarks exist. Using this data it was our goal to establish baseline benchmarks for a variety of data metrics and to begin to establish validated return to play criteria.Methods:GPS records of a consecutive series of Division I NCAA football players were reviewed between 2015 and 2018. Ten metrics were gathered for healthy control players from eight positions (defensive back, wide receiver, running back, linebacker, tight-end, defensive line, offensive line, and quarter back. These metrics consisted of: total distance, total load, explosive yardage, explosive ratio, maximum velocity, inertial movement analysis (IMA) acceleration, IMA deceleration, change of direction (COD) left, and COD right. Average normal values were determined per session for healthy players. Overall we examined 198 player seasons data, 50 (DB), 37 (WR), 20 (RB), 47 (LB), 14 (TE) 14 (DL), 10 (OL), and 6 (QB) respectively.Results:Healthy control averages for total distance was 5456.9 yards (DB), 4973.8 yards (WR), 4260.5 yards (RB), 4054.8 yards (LB), 4334.2 yards (TE), 3498.1 yards (DL), 3274.7 yards (OL), and 4199.2 yards (QB) respectively. Average total load was 492.8 (DB), 463.8 (WR), 393.0 (RB), 367.0 (LB), 423.9 (TE), 389.7 (DL), 381.2 (OL), and 410.8 (QB) respectively. Average explosive yardage was 472.7 (DB), 605.1 (WR), 454.5 (RB), 190.1 (LB), 320.7 (TE) 107.5 (DL), 70.6 (OL), and 191.8 (QB) respectively. Average explosive ratio was 0.847 (DB), 0.855 (WR), 1.045 (RB), 0.989 (LB), 0.985 (TE) 1.53 (DL), 1.31(OL), and 1.66 (QB) respectively. Average maximum velocity was 18.3 (DB), 17.2 (WR), 17.4 (RB), 15.7 (LB), 16.1 (TE) 13.7 (DL), 12.0 (OL), and 16.6 (QB) respectively. Average acceleration was 9.27 (DB), 8.53 (WR), 9.13 (RB), 9.78 (LB), 12.01 (TE) 21.7 (DL), 16.5 (OL), and 47.1 (QB) respectively. Average deceleration was 6.11 (DB), 4.02 (WR), 4.74 (RB), 6.11 (LB), 5.68 (TE) 8.79 (DL), 9.12 (OL), and 1.25 (QB) respectively. Average COD towards left was 6.55 (DB), 7.24 (WR), 9.09 (RB), 6.98 (LB), 9.38 (TE), 13.4 (DL), 11.3 (OL), and 8.22 (QB) respectively. Average COD towards right was 5.80 (DB), 6.45 (WR), 7.84 (RB), 5.91 (LB), 6.74 (TE) 12.5 (DL), 10.7 (OL), and 6.62 (QB) respectively.Conclusion:With the established healthy averages we now have a starting point for comparison of injured athletes and their rehabilitation progress. Categories most closely correlating with return to play following specific injuries is the next step. Additionally, this information may be used in injury prevention, detecting when an athlete may be overly fatigued and at great risk for injury. More data is needed to validate these numbers as well as establish criteria for healthy return to play.

Quantitatively exploring the relationship between eye movement and driving behavior under the effect of different complex diagrammatic guide signs

Complex diagrammatic guide signs (DGSs) are widely used. To study the influence of DGSs with different complexities on drivers’ cognition, four types of typical DGSs on urban expressways in Beijing, China, were studied through a driving simulator experiment. Three indicators related to eye movement and three indicators related to driving behavior were collected and analyzed. The results indicated that the complexities of DGSs significantly increased the number of fixations, increased the number of saccades and decreased the duration of the first fixation on DGSs. More complex DGSs result in a greater difficulty for drivers in recognizing the destination on the DGSs. The complexities of DGSs also had a significant effect on driving behavior, including increasing the standard deviation of the average speed, increasing the driving distance during an acceleration change and increasing the average deceleration. When drivers observed a highly complex DGS, the vehicle speed appeared to significantly fluctuate and decrease, and drivers required a long time to comprehend the DGSs. Under the effect of different complex DGSs, indicators of the drivers’ eye movement and driving behavior are closely correlated, and the average relational degree is 0.645. In particular, relations of the number of saccades on DGSs with three indicators of driving behavior and of the driving distance during an acceleration change with two indicators of eye movement are closer than the relations between other parameters. This study provides a foundation for the influence of DGSs on drivers’ brain cognition and the optimization of complex DGSs, which will be investigated in future research.

An Analysis of Sport Bike Motorcycle Dynamics during Front Wheel Over-Braking

<div class="section abstract"><div class="htmlview paragraph">There is extensive literature on motorcycle skid/brake to stop testing on a host of motorcycle types, rider experience, brake system configurations and the associated deceleration rates. Very little information exists on deceleration rates involved with over-braking the front wheel. The subject of this paper addresses the deceleration rates of sport bike type motorcycles during over-braking of the front wheel. Based on the physics of a two-wheeled vehicle like the motorcycle, once the front wheel is over-braked and becomes locked, the rider has very little time to recover from the skid and often times falls. Another over-braking scenario, especially on sport bike type motorcycles, is the possibility of the rear wheel lifting and pitching over the front wheel. During the initial phase of braking, weight transfer to the front wheel occurs creating a greater level of traction. As the motorcycle begins to fall or pitch over, the weight on the front wheel decreases significantly and therefore the frictional force decreases significantly as well. The goal of this publication was to perform maximum front wheel brake testing that involves front wheel skid-to-fall as well as front wheel brake-to-pitch over scenarios on various sport bike motorcycles and determine an applicable deceleration rate.</div><div class="htmlview paragraph">Three motorcycles; a 2002 Kawasaki ZRX1200R, a 2006 Yamaha YZF-R6, and a 2013 Ninja EX300 were subject to various maximum front wheel brake tests. The speed of the motorcycle at brake application ranged from 50 to 60 mph. The results of the testing concluded that the average deceleration rates during front wheel skid-to-fall tests were in the range of 0.32-0.8g depending on the lean angle of the motorcycle at brake application. The average deceleration rates for the front wheel brake-to-pitch over tests were in the range of 0.8-0.86g.</div></div>

Deceleration of C iv and Si iv Broad Absorption Lines in X-Ray Bright Quasar SDSS-J092345+512710

Abstract We report a synchronized kinematic shift of C iv and Si iv broad absorption lines (BAL) in a high-ionization, radio-loud, and X-ray bright quasar SDSS-J092345+512710 (at ∼ 2.1627). This quasar shows two broad absorption components (blue component at v ∼ 14,000 km s−1, and red component at v ∼ 4000 km s−1 with respect to the quasars systemic redshift). The absorption profiles of C iv and Si iv BAL of the blue component show a decrease in outflow velocity with an average deceleration rate of cm s−2 and cm s−2 over a rest-frame time span of 4.15 yr. We do not see any acceleration-like signature in the red component. This is consistent with dramatic variabilities usually seen at high velocities. During our monitoring period the quasar has shown no strong continuum variability. We suggest the observed variability could be related to the time dependent changes in disk wind parameters like launching radius, initial flow velocity, or mass outflow rate.