Total Pitch Research Articles

A Retrospective Analysis of Major League Baseball Hit-by-Pitch Rates before and after the Crackdown on Foreign Substance Use.

Determine whether there was an increased incidence of hit-by-pitch events in Major League Baseball (MLB) following the decision to enforce the foreign substance ban for pitchers during the 2021 season. Descriptive Epidemiological Study. Major League Baseball hit-by-pitch data from publicly available Web sites ( mlb.com and fangraphs.com ). Major League Baseball players during the 2017, 2018, 2019, 2021, and 2022 seasons. Hit-by-pitch exposure data by season and individual pitch type. Hit-by-pitch incidence rates from the 2017 to 2019 seasons (preenforcement) and the 2021 to 2022 seasons (postenforcement). Rates were compared with incidence rate ratios (IRRs). Hit-by-pitch incidence rate increased from 2.66 to 3.06 per 1000 total pitches (IRR, 1.15 [95% CI, 1.08-1.23]; P < 0.0001) following the enforcement. Incidence rates for 2017, 2018, and 2019 did not differ from each other individually, but incidence rate of all 3 seasons individually were significantly lower than that for the 2021 season ( P < 0.005). Sliders were 29% more likely to hit batters following the enforcement ( P = 0.0015). Major League Baseball batters were hit by pitches at a significantly higher rate following the league's crackdown on foreign substance use for the 2021 seasons compared with the same time of year during the 2017 to 2019 seasons. This was followed by a slight regression toward preenforcement levels during the 2022 season.

Revolutionizing gear hobbing machine precision: Innovative thermal error compensation and intelligent error control with enhanced crystal structure algorithm and self-attention bidirectional minimal gated unit network

The thermal error stands as a pivotal determinant, significantly impacting both the precision and its stability of gear hobbing processes. Thus far, conspicuous delays in compensation and insufficiencies in precision have been duly noted. To achieve a proficient and exceedingly precise thermal error compensation, an intricate mathematical correlation is expounded, delineating the connection between the spatial pose error of the hob and the inherent thermal error in the gear hobbing machine. In addressing the thermal error linked to the B-axis, a bidirectional-minimal gated unit network is harnessed to characterize long-term memory attributes. An advanced crystal structure algorithm is introduced, encompassing components such as the population initialization mechanism, the nonlinear convergence factor, the Gaussian perturbation mechanism, and an enhanced optimization equation. The weights of the bidirectional-minimal gated unit network are judiciously assigned via the self-attention mechanism. This innovation, recognized as the improved crystal structure algorithm-self-attention-bidirectional-minimal gated unit network, is introduced for the training of the thermal error model for the B-axis. Subsequently, thermal analysis models are formulated, yielding the thermal errors of the X- and Z- axes. An error control model and an error decoupling model are established, employing the thermal errors of the B-, X-, and Z- axes as their input. Ultimately, an intelligent error control system is crafted, in which the error control model, error decoupling model, and thermal error model are seamlessly integrated. The aim is to mitigate tooth flank errors. With the integration of the intelligent error control system, the levels of precision pertaining to gear helix deviation, maximum deviation of a single pitch, and cumulative total pitch deviation are elevated by one, one, and two levels, respectively. More significantly, the geometric error reduction of the tooth flank achieved by the meticulously designed intelligent error control system surpasses that of traditional pitch compensation by a substantial margin. Furthermore, the execution efficiency of the intelligent error control system, when operating within the machine-edge-fog-cloud framework, exhibits a remarkable improvement of 24.18%, 16.20%, and 57.84% when compared to the intelligent error control system operating within the machine-edge-cloud, machine-fog-cloud, and machine-cloud frameworks, respectively.

A Novel Wrench–Current Decoupling Strategy to Extend the Use of Small Lookup Data for a Long-Range Maglev Planar Motor

The maglev planar motor is one of the most promising industrial applications. The planar motor can increase flexibility in modern manufacturing with the multidirectional motion of the mover. In levitation control, the decoupling matrix is used to decouple the strong cross-coupling effect. The Lorentz force-based wrench matrices can be precomputed and stored in the lookup table. However, the motion range is restricted by the data range. This paper presents a wrench–current decoupling strategy to extend the use of small lookup data for long-range planar motion. The horizontal data range is 40 mm by 40 mm, which is determined from the minimally repetitive area of the planar coil array. The quadrant symmetry transformation is used to estimate the data for other areas. The experiment results demonstrated the accomplishment of the developed technique for long-range motion with a maximum motion stroke of 380 mm. The disc-magnet movers can levitate with a large air gap of 30 mm and have a total roll and pitch rotation range of 20 degrees.

High-Density Vertical Transistors with Pitch Size Down to 20nm.

Vertical field effect transistors (VFETs) have attracted considerable interest for developing ultra-scaled devices. In particular, individual VFET can be stacked on top of another and does not consume additional chip footprint beyond what is needed for a single device at the bottom, representing another dimension for high-density transistors. However, high-density VFETs with small pitch size are difficult to fabricate and is largely limited by the trade-offs between drain thickness and its conductivity. Here, a simple approach is reported to scale the drain to sub-10nm. By combining 7nm thick Au with monolayer graphene, the hybrid drain demonstrates metallic behavior with low sheet resistance of ≈100 Ω sq-1 . By van der Waals laminating the hybrid drain on top of 3nm thick channel and scaling gate stack, the total VFET pitch size down to 20nm and demonstrates a higher on-state current of 730A cm-2 . Furthermore, three individual VFETs together are vertically stacked within a vertical distance of 59nm, representing the record low pitch size for vertical transistors. The method pushes the scaling limit and pitch size limit of VFET, opening up a new pathway for high-density vertical transistors and integrated circuits.

Optimization of heterojunction back-contact (HBC) crystalline silicon solar cell based on Quokka simulation

For heterojunction back-contact (HBC) crystalline silicon (c-Si) solar cell based on n-type c-Si wafer, the effects of various wafer properties and geometric features of the solar cell back side on the solar cell current-voltage (I-V) performance were systematically studied by Quokka simulation, including the wafer thickness, resistivity and bulk lifetime, the emitter (P region) percentage on the surface, the total pitch of P and N regions, and the contact ratio of the transparent conductive oxide (TCO) film on the P or N region. The preferred values of such parameters for the HBC solar cell to get high efficiency were proposed. The emitter percentage is 80%, the total pitch of P and N is 1.6 mm, the wafer thickness is in the range of 90–120 µm, the wafer resistivity is 0.5 Ω·cm-0.9 Ω·cm, the wafer bulk lifetime is not less than 4 ms, and as long as the cell is not short-circuited, the larger the contact ratio of the TCO, the higher the cell efficiency.

Poster 370: Pitcher Utilization Patterns in NCAA Softball as Compared to Baseball

Objectives: Pitch counts have become a hot topic in baseball over the past two decades since being linked with injury risk. While the National Collegiate Athletic Association (NCAA) has yet to enforce a pitch count rule for participating baseball teams, multiple organizations including the MLB’s Pitch Smart provide age-based guidelines for limiting risk of injury in baseball pitchers through utilization of pitch count limits and rest time. These are generally enforced for youth and high school baseball players. No such recommendations exist for softball despite evidence showing that the underhand windmill pitching motion is not nearly as physiologically benign as once thought. The aims of this study were to compare the patterns of pitcher utilization between elite collegiate baseball and softball teams. Methods: Data was collected from the publicly available websites of baseball and softball teams which participated in the NCAA Division I softball and baseball College World Series from the years 2016 through 2021. The year 2020 was excluded due to a shortened season related to the COVID-19 pandemic. Team data collected included total number of athletes and pitchers per team, including only those pitchers listed as having &gt;0 innings pitched for the season. Data collected for each individual pitcher included the season total number of innings pitched and total number of game appearances. Total pitch counts were not available on a majority of publicly available team websites for both softball and baseball. Unpaired student’s t test was used to compare normally distributed data, and a Wilcoxon- Mann-Whitney Test was used for non-normally distributed data. A P value &lt;0.05 was considered statistically significant for all calculations. Results: Forty softball teams and forty baseball teams, with 158 softball pitchers and 612 baseball pitchers were included. Baseball team rosters averaged significantly more total players, more pitchers, and a greater percentage of their roster was made up of pitchers as compared to softball teams, as summarized in table 1. The range of pitchers per team is notable, with baseball teams listing 12 to 24 pitchers as compared to softball with 3 to 7 pitchers per team. The average percentage of baseball rosters comprised of pitchers is more than twice that seen in softball. On an individual level, it is apparent that softball pitchers see considerably more playing time than their baseball counterparts, with significantly more innings pitched and appearances per season, and greater innings pitched per game as summarized in table 2. Again the range within these data points is striking, with a maximum of 134.2 innings pitched in a season by baseball pitchers as compared to a maximum of 287.0 innings in softball. Only 7.35% of baseball pitchers threw more than 100 innings in a season as compared to 43.70% of softball pitchers. Conclusions: This analysis of elite collegiate baseball and softball teams highlights a significant discrepancy in the physical expectations of their respective pitchers. Due to the significantly lesser representation of pitchers on softball rosters as compared to baseball, each individual pitcher sees a higher pitch count overall and per game, and by playing in more total games, sees less recovery time as well. The tie between pitch count and injury risk is well established and respected within baseball, and further injury-based research should be conducted to consider support of similar limitations for softball pitchers. [Table: see text][Table: see text]

Hidden Pitches in Major League Baseball: What Are the Injury Implications of These Often Overlooked Pitches?

Pitch counts are tightly monitored in Major League Baseball (MLB). Hidden pitches-including warm-up pitches before and between innings and pitches before the starting/relieving pitcher's appearance in a game-are not as closely monitored. To report the number of hidden pitches thrown per game and over the course of a season for a single organization. We hypothesized that players who threw more hidden pitches would be at an increased risk of injury compared with those who threw fewer hidden pitches. Case-control study; Level of evidence, 3. All pitchers who played for a single MLB organization in the 2021 season were included. Hidden pitches, in-game pitches, and total pitches thrown during all games in the season were recorded. Injuries to these pitchers were also recorded. Players were defined as having an injury if they spent any time on the injured list. Overall, 137 pitchers were included, 66 (48%) of whom sustained an injury and were placed on the IL during the 2021 season (mean time on IL, 53.6 ± 45.6 days). Of the 66 players who sustained an injury, 18 (27.3%) sustained an elbow injury, while 12 (18.2%) sustained a shoulder injury. Only 1 player sustained an ulnar collateral ligament tear. When comparing hidden pitches, in-game pitches, and total pitches between pitchers who sustained an injury and those who did not, there were no significant differences between groups (P = .150; P = .830; and P = .377, respectively). On average, hidden pitches made up 45.4% of the total number of pitches thrown during the course of the season. When evaluating the number of hidden pitches as a percentage of the total number of pitches thrown in a season, there was no significant difference between pitchers who sustained an injury and those who did not (P = .654). MLB pitchers who sustained an injury did not throw more hidden pitches than those who did not sustain an injury. Larger scale studies are needed to confirm the results of this single-team study.

Relationship Between Pitch Counts and Shoulder Strength in Collegiate Baseball Players.

Gagnon, A, Payette, J, Park, M, Juras, K, and Slater, L. Relationship between pitch counts and shoulder strength in collegiate baseball players. J Strength Cond Res 37(9): 1860-1864, 2023-Large volumes of throwing leads to changes in shoulder strength that have been associated with increased risk of injury. The purpose of this study was to investigate the relationship between throwing volume and eccentric shoulder strength. Twelve NCAA Division I baseball pitchers volunteered to participate. Prepractice and postpractice eccentric shoulder strength was measured using a handheld dynamometer at 30°/second. Change in strength was calculated as the prepractice strength measure subtracted from the postpractice strength measure. After initial testing, subjects self-reported pitch counts before completing postpractice strength testing. Subjects were separated into high-strength and low-strength groups based on the median external rotation strength. Paired t -tests were used to compare change in shoulder strength and Pearson's r correlations were used to quantify the association between pitches and change in strength. There were no changes between prestrength and poststrength assessments in external rotation strength or internal rotation strength for the entire group. When divided into strength groups, correlations between strength and total pitches were nonsignificant for the high-strength group but were strong for both external rotation ( r = -0.87, p = 0.025) and internal rotation ( r = -0.91, p = 0.013) in the low-strength group. Pitchers with lower shoulder eccentric strength at baseline demonstrated greater declines in strength, whereas pitchers with higher shoulder eccentric strength did not demonstrate changes in strength. Changes in strength during practice could lead to compensatory movement that may predispose athletes to injury. Sport performance professionals may benefit from obtaining eccentric shoulder strength to assist with performance periodization and rehabilitation after injury.

Variability in Pitch Count Limits and Rest Day Requirements by State: Implications of Season-Long Pitch Counts in High School Baseball Pitchers

Background: It is unknown how different pitch count limits and rest day requirements affect cumulative pitch counts during a baseball season. Purpose: To determine (1) the variability of pitch count rules in high school baseball and (2) the theoretical effect of different pitch count limits and rest day combinations on game, weekly, and seasonal pitch totals in high school baseball pitchers. Study Design: Cross-sectional study. Methods: Pitch count rules for the 2019-2020 academic year for 48 sanctioned states were recorded from each state’s athletic association website. Maximum pitch count limits were recorded along with the number of pitches allowed before requiring 0 to 5 rest days before the next pitching outing. Rules were also analyzed for several distinctions, including the athlete’s level of competition, age, and grade. To determine the effect of pitch count rules and rest days, a theoretical 3-month season was calculated in the following scenarios: (1) variable maximum pitch count limits with a universal 3-day rest requirement, (2) universal 110 pitch count limit with variable rest day requirements (3, 4, or 5 days), and (3) actual pitch count limits and required rest days for every state assuming pitchers throw as many pitches as allowed. Analysis of variance and Student t tests were used to compare between-group and intragroup seasonal pitch totals based on variations in required rest days. Results: The most common maximum pitch count limit for a varsity high school athlete was 110 pitches (range, 100-125 pitches) with 4 rest days (range, 0-5 days). We found that 23 states (48%) did not make distinctions for pitch count rules based on the athlete’s level of competition, age, or grade. We noted a 25% increase in total seasonal pitch counts between the smallest and largest pitch count limit when assuming constant 3-day rest. We found a 53% difference in total seasonal pitch count when rest days varied between 3 and 5 days with a constant 110-pitch limit. Allowing 140 pitches in a 4-day span without a specific rest day requirement resulted in the highest seasonal pitch count (Nevada). There was a 49% difference in maximum seasonal pitch counts between the most and least restrictive states (P < .001). Submaximum pitch limits resulted in higher seasonal pitch counts than maximum pitch limits in 56% of states. Conclusion: Pitch count rules vary widely by state. Required rest days influenced total seasonal pitch counts more than maximum or submaximum pitch count limits.

Effect of Pitching Restrictions and Mound Distance on Youth Baseball Pitch Counts

Background:Studies have shown that higher pitch counts are directly related to a greater incidence of elbow and shoulder pain among youth baseball pitchers.Purpose/Hypothesis:The purpose of this study was to examine the effect of different pitching restriction rules on the number of pitches thrown in youth baseball leagues. We hypothesized that more pitches would be thrown in leagues with inning restrictions versus leagues with pitch count restrictions as well as in leagues with a longer mound distance (from pitching mound to home plate).Study Design:Cohort study; Level of evidence, 2.Methods:Pitch count data were collected for 2 consecutive years over a 10-week season from 3 different leagues of 9- to 12-year-old baseball players in a single city. The Eastern league had a pitch count restriction and 46-ft (14.02-m) mound distance. The Southeastern and South leagues’ pitching restrictions were based on innings per week. The Southeastern league had a 50-ft (15.24-m) mound distance, while the South league had a 46-ft mound distance. Comparisons of total seasonal pitches thrown were made of the 3 highest-volume pitchers on each team. League averages for each value were then compared utilizing analysis of variance with Bonferroni post hoc analysis. The number of pitchers in each league who threw >600 pitches per season was compared using the chi-square test.Results:No significant difference in seasonal pitch counts or innings pitched was noted between the Eastern and South leagues, which differed only in their pitching restrictions. The Southeastern league, with a longer mound distance, was found to have higher seasonal pitch counts per thrower (598 ± 195 pitches) than the South league (463 ± 198 pitches) for the 3 highest-volume throwers for each team (P = .004). The Southeastern league also had a significantly larger number of pitchers who threw >600 pitches per season (33 vs 20 for Eastern and 13 for South; P = .009).Conclusion:There was no significant difference in seasonal pitch counts when the leagues in this study differed based on pitching restrictions. However, the league with a greater mound distance (Southeastern) had higher seasonal pitch counts for the highest-volume throwers. Pitching restrictions based on pitch counts, as opposed to innings, may be advisable.

Flutter of a finite rectangular Wing’D mill in pitch and heave

Exact solutions of flutter are explored for a mode suitable for an oscillating 2D hydrofoil version of the summarised FlutterWing windpump which radically surpasses the old rotary fanpump. The imaginary part G of the 1D Theodorsen wake lift factor T rises singularly from the steady to allow 1D pure pitch flutter around the leading edge at low frequency. But its logarithmic infinite negative pitch damping by the shed vorticity is capped by the log of the 2D span. The downwash of an oscillating trailing (tip) vortex is reduced by a function of the reduced frequency based on spanwise distance. Its lag damps pitch and further raises the pitch unstable aspect ratio A to above 36. All binary pitch &amp; heave neutral flutter frequency contours in (inertia, imbalance) space still pass through a nexus of the same total pitch inertia and imbalance as the corrected virtual mass concentrated at ¾ chord, a very high total in water. The internal bound windwise vortex from ¼ chord to trailing edge reduces as A−2 the 1D lift slope at all frequencies. It expands the 1D T = ½ double root of high frequency elliptical contours kissing the low frequency limit line at the nexus to make them dip below the line to the right of the nexus as hyperbolae with the nexal ray as left asymptote. Thus low A discovers a new wedge of high frequency binary flutter with real mass moments less than the virtual, as in water.

Durability Analysis of the Prototype Test Rig for Main Rotors

This paper presents an analysis of the strength of a prototype test rig for testing rotors of unmanned aerial vehicles. Digital design software was used for the design work that covered the creation of a virtual model of the test rig and strength analysis of its key elements. The paper discusses the test rig solutions, applied to date, of the small main rotor research. From the assumed operational parameters and structural parameters of the rotor, the main forces acting on the designed structure were determined: lifting force, reaction torque and empty mass of the test rig. Suitable actuators of the control system enabling the regulation of the total pitch and periodic pitch of the rotor, within the full range of the angle of attack, were selected for the rotor under test. The FEM (Finite Element Method) strength analysis was carried out for the proposed support structure and the correctness of the design was verified.

Numerical Calibration and Investigation of the Influence of Reynolds Number on Measurements With Five-Hole Probes in Compressible Flows

Abstract This paper presents an investigation into the numerical and experimental calibration of a five-hole probe and effects of Reynolds number variations on the characteristics of the probe. The test object is a cone-type drilled elbow probe with a head diameter of 1.59 mm and a cone angle of 60 deg. The experimental calibration maps of four different probes of the same type and nominal geometry are compared. A significant variation of the curves can be observed especially at high yaw angles. This led to a visual inspection of the probes with a 3D measurement system. The actual geometry of the three used probes and the surface and radii in particular varied significantly from that of the unused spare probe. Furthermore, a numerical calibration map of the ideal probe was generated for a Mach number of Ma = 0.3. A comparison between the experimental and numerical calibration coefficients revealed that total pressure, yaw and pitch angle were reproduced reasonably well. The dynamic pressure coefficient, however, has a considerable offset. Finally, a parameter study of the effect of varying the Reynolds number over different yaw angles was conducted. The calibration Reynolds number is of the order of Re = 1 · 104 and was varied between 0.5 · 104 &amp;lt; Re &amp;lt; 6 · 104. While the results suggest that only minor measurement errors occur for yaw angle, total pressure and static pressure, a relatively large error was observed for pitch angle measurements.

Magnetic Resonance Imaging Findings of the Asymptomatic Shoulder May Impact Performance, Not Future Injury List Placement in Major League Baseball Pitchers

PurposeTo evaluate preseason shoulder magnetic resonance images (MRIs) obtained from pitchers entering either major or minor league baseball (MLB) and correlate findings with subsequent injury, operative repair, and placement on the injured list (IL).MethodsPreseason-MRI of the throwing shoulders of professional-level baseball pitchers, taken during routine evaluations at a single organization (2004-2017) were retrospectively reviewed. Publicly available databases were queried to exclude pitchers with known injuries prior to pre-signing imaging. Three blinded reviewers reviewed all MRI scans independently to evaluate for the presence of abnormalities in the rotator cuff (RTC), labrum, capsule, long-head of the biceps tendon (LHBT), and humeral head. Binary imaging findings were correlated to future placement on the IL for subsequent shoulder complaints. Bivariate statistics using Student’s t-tests and Fisher exact tests (both α = .05) were used in this study.ResultsA total of 38 asymptomatic pitchers with shoulder MRIs were included. Pitchers had a mean (±SD) age of 28.2 ± 4.9 and had pitched an average of 119.6 ± 143.8 career games. Pitchers with partial articular-sided RTC tears (P = .04) or intra-articular BT hyperintensity (P = .04) on preseason MRI demonstrated an association with the need for future surgery. Pitchers with evidence of labral heterogeneity demonstrated greater total career pitch counts (10,034.1 vs 2,465.3; P = .04). Evidence of a posterior-superior humeral cyst was associated with decreased strikeouts per 9 innings (6.1 vs 8.0; P = .039) and total strikeout percentage (16.1% vs 23.2%; P = .04).ConclusionAlthough there was a significant difference in the percent of various radiographic findings between the injured and healthy cohort, no MRI findings were predictive of future IL placement or duration of placement. The presence of a posterior superior humeral cyst was associated with decreased strikeout rates at 2 and 3 years, the presence of a labral tear was associated with decreased earned run average (ERA) at 3 years and decreased career strikeout percentages, and increased capsular signal was associated with decreased 5-year ERA.Level of EvidenceLevel IV, retrospective study.

Gear pitch rapid measurement by a point laser sensor

With the continuous improvement of the theory and method of gear measurement, the effectiveness of gear contact measurement is reduced, making it difficult to meet the need for 100% gear detection. To improve the measurement efficiency and make effective use of the full tooth surface data, a gear pitch rapid measurement method by point laser sensor is proposed. This method studies the principle of measuring the gear based on a laser point sensor, and the efficient model of collection and analysis of tooth surface data is established. Then the evaluation of the pitch deviation is completed, including the individual single pitch deviation, the single pitch deviation, the individual cumulative pitch deviation, and the total cumulative pitch deviation. Additionally, the pitch deviation of the multiple cross-sections is investigated, which may characterize the overall pitch deviation of the tooth surface. Compared to the gear measuring center P26, the experimental results show that the optical measurement of pitch deviation is feasible and efficient. Depending on the different measuring conditions, the offset status of the sensor can be selected to meet the different efficiency and accuracy requirements. The research and application potential of a point laser sensor in gear measurement is wide-ranging.

Angle of attack prediction using recurrent neural networks in flight conditions with faulty sensors in the case of F-16 fighter jet

The angle of attack (AOA) is one of the critical parameters in a fixed-wing aircraft because all aerodynamic forces are functions of the AOA. Most methods for estimation of the AOA do not provide information on the method’s performance in the presence of noise, faulty total velocity measurement, and faulty pitch rate measurement. This paper investigates data-driven modeling of the F-16 fighter jet and AOA prediction in flight conditions with faulty sensor measurements using recurrent neural networks (RNNs). The F-16 fighter jet is modeled in several architectures: simpleRNN (sRNN), long-short-term memory (LSTM), gated recurrent unit (GRU), and the combinations LSTM-GRU, sRNN-GRU, and sRNN-LSTM. The developed models are tested by their performance to predict the AOA of the F-16 fighter jet in flight conditions with faulty sensor measurements: faulty total velocity measurement, faulty pitch rate and total velocity measurement, and faulty AOA measurement. We show the model obtained using sRNN trained with the adaptive momentum estimation algorithm (Adam) produces more exact predictions during faulty total velocity measurement and faulty total velocity and pitch rate measurement but fails to perform well during faulty AOA measurement. The sRNN-GRU combinations with the GRU layer closer to the output layer performed better than all the other networks. When using this architecture, the correlation and mean squared error (MSE) between the true (real) value and the predicted value during faulty AOA measurement increased by 0.12 correlation value and the MSE decreased by 4.3 degrees if one uses only sRNN. In the sRNN-GRU combined architecture, moving the GRU closer to the output layer produced a model with better predicted values.

PREDICTION OF THE DYNAMIC RESPONSE OF A SHIP IN HEAD WAVES USING OPENFOAM TOOLBOX

Ships and marine structures, such as oil tanker, offshore platforms, etc., usually face extreme seaway environment in real situation. If under the action of strong waves large amplitude motions will occur, with the result that they may not work as usual or even lose stability. Thus, it is of great importance to access their dynamic responses under such bad conditions at the initial design stage, so as to ensure normal usage and safety. Herein, the original RANS (Reynolds-Averaged Navier- Stokes) solver based on OpenFOAM Toolbox has been extended to predict dynamic responses of ships and marine structures in waves. A new “inlet-velocity boundary condition” was implemented to generate waves. A damping term for wave absorption was added to the right-hand side of RANS equations in order to avoid wave reflection from the boundary where waves leave the computational domain. The related numerical methods are described in this paper. The purpose of this paper is to present a validation of the approach used. The prediction of the dynamic response of a ship in head waves was the focus. Five cases with different wave lengths and heights were considered. The predicted results, i.e. time histories of total resistance, heave and pitch, were compared with available experimental data and analysed. In addition, due to current experience it is very necessary that effort is devoted to determining appropriate grid and time step, so as to ensure the quality of waves generated.

Pitching Behaviors in Youth Baseball: Comparison With the Pitch Smart Guidelines.

Background:The Pitch Smart guidelines aim to limit youth baseball pitching behaviors associated with overuse injuries. Despite many youth baseball leagues being compliant with the guidelines, during tournaments, pitch count restrictions or guidelines are often not followed.Purpose:To perform a quantitative analysis of pitch counts in youth baseball players and evaluate compliance with regard to the Pitch Smart guidelines in the tournament setting.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Included in the analysis were 100 youth baseball teams that competed in the 8-and-under to 14-and-under age divisions during the 2019 tournament season. Pitching data were compared with the Pitch Smart guidelines. Violations were identified as (1) exceeding maximum daily pitch count, (2) inadequate rest between pitching events, and (3) pitching more than 1 event on the same day. Pitcher and game factors were analyzed for possible relationships to guideline violations using mixed-effects negative binomial regression models, with comparisons of violations using rate ratios (RRs).Results:Analysis included 1046 pitchers and 2439 games. There were 1866 total Pitch Smart guideline violations, with 48.6% of pitchers having at least 1 violation. Inadequate rest was the most common reason for violation, with noncompliance occurring in 43.3% of pitchers. The highest rate of any violation (0.32 per appearance) occurred in the 8-and-under age division. High-volume pitchers had increased violation rates in each category compared with low-volume pitchers (P < .001). Violation rates were increased more than twice the rate when pitchers participated in ≥5 consecutive games without a rest day when compared with a single game (RR, 2.48; P < .001).Conclusion:Noncompliance with Pitch Smart guidelines in tournament settings occurred in more than 90% of teams and almost half of all pitchers. Factors associated with noncompliance included younger pitcher age, high-volume pitching, and pitching in multiple consecutive games. Education of tournament directors, coaches, parents, and athletes regarding pitching guidelines is warranted in order to limit the risk of injury.

An Eco-Cruise Control for Electric Vehicles Moving on Slope Road with Constant Speed

The unreasonable actuation of electric vehicle’s motor drive system usually results in a lot of unwanted energy consumption on a slope road. This paper proposes an eco-cruise control (ECC) scheme based on the driving condition estimation to decrease electric vehicle’s energy consumption in the constant-speed cruise control mode. The eco-cruise control scheme is realized by reducing the unreasonable actuation of the motor drive system. The vehicle’s total mass and pitch angle are estimated in real time by using an improved base-vector-based cross iteration estimator (BVCIE). Based on the estimated results, the required torque is predicted. Combining the speed deviation between the desired speed and the real speed, and the torque deviation between the required torque and the real torque, a three-power nonlinear controller of the ECC scheme is designed. The ECC scheme is validated on a slope road with different cruise speeds on a cosimulation platform, and the results indicate that the proposed strategy enjoys a better speed maintenance ability and energy efficiency compared with the benchmarked cruise control.

Association Between Pitch Break on the 4-Seam Fastball and Slider and Shoulder Injury in Major League Baseball Pitchers: A Case-Control Study.

Background:Few specific risk factors are known for shoulder injury in professional pitchers. New pitch-tracking data allow for risk stratification based on advanced metrics.Purpose/Hypothesis:The purpose of this study was to determine the association between shoulder injury, pitch frequency, and pitch metrics (velocity, total break, break angle, and spin rate) for the 4-seam fastball, curveball, and slider. We hypothesized that more frequent use of the 4-seam fastball would be associated with shoulder injury.Study Design:Case-control study; Level of evidence, 3.Methods:The Major League Baseball (MLB) database was queried for pitchers who had been placed on the injury list (IL) with a shoulder injury between 2015 and 2019. Injured pitchers were matched 1:1 with controls (pitchers not on the IL with a shoulder injury during the study period), based on age (±1 year), history of ulnar collateral ligament reconstruction, position (starter vs reliever), and pitches thrown during the injury season (±500). Pitch frequency, velocity, horizontal break, vertical break, total break, and spin rate for the season were collected from the Baseball Savant website for the 4-seam fastball, curveball, and slider. Univariate analysis was used to determine group differences for individual variables. Multiple logistic regression was performed to determine odds ratios (ORs) for shoulder injury associated with pitch frequency, velocity, total break, break angle, and spin rate. Covariates included age, position, ulnar collateral ligament reconstruction status, expected weighted on-base average, and total pitches thrown.Results:Overall, 233 injured pitchers were evaluated. The most common reason for IL placement was inflammation (78/233; 33.5%) followed by strain or sprain (61/233; 26.2%). Increased total pitch break was associated with an increased risk of shoulder injury for the 4-seam fastball (OR, 1.340 [95% confidence interval (CI), 1.199-1.509]; P < .001) and slider (OR, 1.360 [95% CI, 1.206-1.554]; P < .001). For the slider, a decreased spin rate (OR = 0.998 [95% CI, 0.997-0.999]; P = .026) and a more vertical break angle (OR = 1.170 [95% CI: 1.073-1.278]; P = .004) were associated with increased risk of injury.Conclusion:Increased pitch break of the 4-seam fastball and slider was associated positively with shoulder injury in MLB pitchers. These findings add to the understanding of throwing injury and ability to detect risk using ball-tracking technology.