Entry Angle Research Articles

CFD-DEM analysis of oblique water entry under a polar environment

Research on the water entry behavior of detectors passing through crushed ice zones in polar environments is essential for the exploration of polar oil resources. This study integrates computational fluid dynamics (CFD) and the discrete element method (DEM) with laboratory experiments to analyze projectiles' oblique water entry behavior through crushed ice zones. The investigation reveals that the unique polar environment, characterized by crushed ice accumulation, significantly influences the projectile's water entry behavior. Key parameters, such as water entry angle and the height of ice accumulation, are examined for their impact on the water entry process, flow field evolution, and projectile dynamics. The study identifies a complex multi-body coupling mechanism among the projectile, crushed ice particles, and fluid during oblique water entry. Crushed ice alters the cavity evolution and deflection patterns of projectiles, affecting the flow field dynamics. Variations in water entry angles modify the interaction patterns among the projectile, liquid level, and crushed ice, influencing cavity formation and fluid-ice coupling. Increasing crushed ice height enhances the coupling effects, leading to a greater degree of projectile deflection. These findings provide insights into optimizing detector design and launch strategies, contributing to more efficient oil exploration in polar environments.

Capturing relationships between suturing sub-skills to improve automatic suturing assessment

Suturing skill scores have demonstrated strong predictive capabilities for patient functional recovery. The suturing can be broken down into several substep components, including needle repositioning, needle entry angle, etc. Artificial intelligence (AI) systems have been explored to automate suturing skill scoring. Traditional approaches to skill assessment typically focus on evaluating individual sub-skills required for particular substeps in isolation. However, surgical procedures require the integration and coordination of multiple sub-skills to achieve successful outcomes. Significant associations among the technical sub-skill have been established by existing studies. In this paper, we propose a framework for joint skill assessment that takes into account the interconnected nature of sub-skills required in surgery. The prior known relationships among sub-skills are firstly identified. Our proposed AI system is then empowered by the prior known relationships to perform the suturing skill scoring for each sub-skill domain simultaneously. Our approach can effectively improve skill assessment performance through the prior known relationships among sub-skills. Through the proposed approach to joint skill assessment, we aspire to enhance the evaluation of surgical proficiency and ultimately improve patient outcomes in surgery.

THE INFLUENCE OF THE ANGLE OF ENTRY INTO THE BELL-SHAPED TIP OF A SHORTENED ROUND SUPERSONIC NOZZLE OF A ROCKET ENGINE ON ITS IMPULSE CHARACTERISTICS

In gas-dynamic studies of rocket engines, much attention is paid to the characteristics of the nozzle — its geometry, momentum, losses, and manifestation of traction characteristics under various operating conditions. This work is devoted to the study of the influence of the entry conditions into the bell-shaped tip of a shortened nozzle on its gas-dynamic and impulse characteristics. We consider shortened nozzles with the same conical supersonic parts and the same total length of the nozzle but with different angles of connection of the conical part of the nozzle with the bell-shaped tip. When working at sea level, changing the angle of inclination of the forming bell-shaped tip does not significantly change the value of the static pressure at the corner point and the coefficient of nozzle impulse. This is due to the occurrence of flow separation at the corner point and the presence of a large-scale vortex. With a continuous flow in the nozzle during the operation of the rocket engine at altitude, the nature of the pressure distribution on the nozzle wall at the corner point differs when the angle of connection of the conical part with the tip changes, and the maximum value at the nozzle section is approximately the same. This fact is explained by the appearance of a hanging shock wave near the tip wall at small entrance angles (30°). The study examines the flow’s impulse characteristics in the nozzle under different pressure values at the inlet and the surrounding environment. The impulse coefficient in terrestrial conditions depends little on changing the tip and decreases with increasing pressure at the nozzle inlet. When working at height, there is a weak effect of changing the angle of entry into the nozzles on the momentum coefficient.

Optimizing flow uniformity and velocity fields in aquaculture tanks by modifying water inlets and nozzles arrangement: A computational fluid dynamics study

Ensuring optimal conditions for fish, especially in terms of uniform velocity fields, is crucial for aquaculture systems to attain self-cleaning efficiency in rearing tanks and better fish behavior, which ultimately impacts their survival and growth. The current study presented a full-scale computational fluid dynamics (CFD) model of three types of circular, square and square arc angle tanks used in aquaculture farms to choose the most optimal tank based on the flow uniformity and velocity field. At the next step, the optimal arrangement of the inlet number, inlet location, inlet angle, as well as the number of nozzles on each inlet was reconfigured to create the most optimal tank. The simulations were done using the CFD software FLUENT distributed by the ANSYS Corporation. The software calculates velocities in the tanks by solving the Reynolds-averaged Navier-Stokes equations of continuity and momentum that govern the mean turbulent flow of water. The results illustrated circular and square arc angle tanks had significantly more uniform fluid velocity compared to the square tanks, which the square arc angle tank due to better flow velocity near the wall and space utilization was selected for further rearrangements. Additionally, the implementation of two entrance pipes near the corner of the two parallel walls with an entry angle of 0° in a square arc angle tank resulted in a more consistent water velocity. As the number of inlet nozzles increased to six, the water streamlines became more uniform, suggesting a more consistent water velocity throughout the tank. However, when the number of input nozzles increased to nine, the tension on the nozzle apertures were increased probably due to the decrease of distance between them. Findings of the present study concluded that two inlets in the corner with an entry angle of 0° and six nozzles on each inlet pipe could provide the optimum water velocity in the square arc angle tanks.

Numerical investigation of sequential water entry for two projectiles at varied entry angles

In this paper, the effect of the water entry angle on the sequential water entry process of two projectiles was investigated numerically. A numerical method is established based on the STAR-CCM+ fluid simulation software, which employs the finite volume method, the volume of fluid multiphase flow model, and overlapping grid technology. The validity of the numerical method was confirmed by comparing the simulation results with experimental data. The sequential water entry processes are simulated at angles of 90°, 75°, 60°, 45°, and 30°, respectively. The flow field characteristics, motion stability, and drag reduction of both projectiles are analyzed. The results show that projectile 1 generates a series of air bubbles shedding from its cavity's tail, which distorts projectile 2's cavity. This air bubble reduces the wet area at projectile 2's head, enhancing its drag reduction capability. Projectile 1's motion remains unaffected by projectile 2 under varying water entry angles, while distinct motion characteristics are observed in projectile 2 due to significant interference from projectile 1. These results provide valuable theoretical insights for further research on sequentially launched trans-media weapons.

Innovative eco-friendly design solutions for energy demands using swirl- induced burner by jets

Addressing the need for innovative burner designs to optimize combustion characteristics and meet energy efficiency goals, this study introduces a novel concept rooted in swirl-induced flames. The proposed burner employs a unique approach to generate air and fuel swirl using four opposing slots in two sets, each set at distinct angles. Incorporating of a channel within the outer casing allows for fine-tuning of entry angles, optimizing the double swirling process. The objective of this research is to enhance combustion characteristics through the implementation of the swirl principle, introducing a tangential velocity component to the airflow or fuel-air mixture upon entry into the burner. Systematic measurements at various entry angles (0°, 15°, 30°, 45°, and 60°) are conducted to identify optimal or near-optimal conditions. The research covers a comparison between flow fields generated by traditional swirled vanes and swirl-induced injection ports at identical inlet conditions, revealing enhanced flame stability and combustion efficiency in the latter configuration. The formation of recirculation zones around the burner, facilitated by increased outer air jet velocities, promotes better mixing and stability. This research contributes valuable insights into burner design and optimization, with implications for improved combustion efficiency and environmental sustainability.

Beam Position Projection Algorithms in Proton Pencil Beam Scanning.

Beam position uncertainties along the beam trajectory arise from the accelerator, beamline, and scanning magnets (SMs). They can be monitored in real time, e.g., through strip ionization chambers (ICs), and treatments can be paused if needed. Delivery is more reliable and accurate if the beam position is projected from monitored nozzle parameters to the isocenter, allowing for accurate online corrections to be performed. Beam position projection algorithms are also used in post-delivery log file analyses. In this paper, we investigate the four potential algorithms that can be applied to all pencil beam scanning (PBS) nozzles. For some combinations of nozzle configurations and algorithms, however, the projection uses beam properties determined offline (e.g., through beam tuning or technical commissioning). The best algorithm minimizes either the total uncertainty (i.e., offline and online) or the total offline uncertainty in the projection. Four beam position algorithms are analyzed (A1-A4). Two nozzle lengths are used as examples: a large nozzle (1.5 m length) and a small nozzle (0.4 m length). Three nozzle configurations are considered: IC after SM, IC before SM, and ICs on both sides. Default uncertainties are selected for ion chamber measurements, nozzle entrance beam position and angle, and scanning magnet angle. The results for other uncertainties can be determined by scaling these results or repeating the error propagation. We show the propagation of errors from two locations and the SM angle to the isocenter for all the algorithms. The best choice of algorithm depends on the nozzle length and is A1 and A3 for the large and small nozzles, respectively. If the total offline uncertainty is to be minimized (a better choice if the offline uncertainty is not stable), the best choice of algorithm changes to A1 for the small nozzle for some hardware configurations. Reducing the nozzle length can help to reduce the gantry size and make proton therapy more accessible. This work is important for designing smaller nozzles and, consequently, smaller gantries. This work is also important for log file analyses.

Study on Water Entry of a 3D Torpedo Based on the Improved Smoothed Particle Hydrodynamics Method

The water entry of a torpedo is a complex nonlinear problem, involving transient impact, free surface deformation, droplet splashing, and fluid–structure coupling, which poses severe challenges to traditional mesh methods. The meshless smoothed particle hydrodynamics (SPH) method shows unique advantages in capturing the complex features of the water entry of the torpedo at different entry angles. However, it still suffers from some inherent shortcomings, such as low surface discretization accuracy, poor discretization flexibility, and low calculation efficiency. In this study, an improved adaptive SPH algorithm is proposed to investigate the water entry of the torpedo accurately and efficiently. This method integrates meshless point generation and adaptive techniques simultaneously. The numerical results demonstrate that when the torpedo vertically enters the water at different velocities, the induced impact loads acting on the head of the torpedo fluctuate significantly with two peak values in the initial stage and thereafter stabilize in a later stage. The impact load acting on the torpedo, the entry depth of the torpedo, the splash height of the droplets, and the size of the cavity generated around the torpedo increase with the increment in the entry velocity. When the torpedo enters the water at different entry angles under the same initial entry velocity, both the vertical and the horizontal movements of the torpedo are observed, which results in more complex variations in parameters along the x- and y-axes. The findings and the corresponding numerical method in this study can provide a certain basis for the future designs of the entry trajectory and the structural bearing capacity of torpedoes.

Investigation of the Impact Load Characteristics during Water Entry of Airdropped Underwater Gliders

Underwater gliders have emerged as effective tools for long-term ocean exploration. Employing aircraft for launching underwater gliders could significantly expand their application. Compared to slender underwater vehicles, the distinctive wing structure of underwater gliders may endure huge impact forces when entering water, leading to more intricate impact load characteristics and potential wing damage. This paper employs a computational fluid dynamics approach to analyze the water entry event of an airdropped underwater glider and its impact load behavior. The results indicate that the glider impact load is enhanced prominently by the wing, and that the extent of enhancement is influenced by the entry attitude. At an entry angle of 80°, the glider exhibits the maximum impact load during different water entry angles. In addition, a larger attack angle indicates a higher glider impact load. Our present study holds significant importance for both the hydrodynamic shape design and water entry strategy control of airdropped underwater gliders.

Experimental investigation on effects of temperature and launch pressure on variations of the impact acceleration in cross media water-entry process

In the paper, effects of temperature and launch pressure on variations of the maximum impact acceleration in cross media water-entry process are systematically investigated via experiments. Results indicated that under the water entry angle of 25°, the maximum impact acceleration increased gradually with the growing of launch pressure from 2.5MPa to 3.0MPa when the temperature is 30°C, 40°C, and 50°C. The maximum impact acceleration decreased constantly with the increase of the temperature from 30°C to 50°C when launch pressure is the constant. According to the comprehensive analysis, effect degrees of variations of the launch pressure on the maximum impact acceleration are more significant than that of the variations of temperature.

Effect of fluid–structure interaction on the oblique water entry of the projectile under the influence of floating ice structure

The water entry of a projectile constrained by polar floating ice presents a unique cross-media challenge. This paper investigates the dynamics of oblique water entry for a projectile influenced by floating ice using the fluid–structure interaction (FSI) method. The validity of the numerical method has been confirmed through experimental validation. The water entry process of a projectile from the side of the floating ice is examined. The evolution of the cavity and the movement patterns of objects as the distance between the projectile and the floating ice decreases toward collision are investigated. The influence of water on the critical collision distance between the projectile and the floating ice during oblique water entry is analyzed. Additionally, the physical mechanism of floating ice deflection through collision is investigated based on the theory of cavity dynamics. Subsequently, the study focuses on the oblique water entry process of a projectile colliding with the upper surface of the floating ice. Different entry angles determine the collision mode between the projectile and the floating ice surface. This study also examines how varying entry angles influence cavity evolution and object movement patterns during oblique collisions. Different collision modes between the projectile and the floating ice lead to asymmetric cavity evolution and various modes of object deflection motion. Finally, changes in the flow field and vortex structure during oblique collisions are studied to examine the influence of the FSI process between the projectile and the floating ice on the flow field.

Design and Parametric Optimization Study of an Eccentric Parallelogram-Type Uprighting Device for Ratoon Rice Stubbles

To address the issue of reduced yield in the second season caused by damaged stubbles resulting from being compressed during the harvesting process of the first season’s ratoon rice, a device for rectifying the compressed stubbles was designed. Utilizing the DEM-MBD coupling simulation method, a simulation analysis was conducted to determine the range of key parameters and verify the feasibility of the solution. Using rotational speed, forward speed, and stubble entry angle as experimental factors and stubble rectification rate and second-season yield as evaluation metrics, a three-factor, three-level Box–Behnken response surface field trial was conducted. The theoretically optimal working parameter combination was found to be a forward speed of 1.4 m/s, device rotational speed of 75 rpm, and stubble entry angle of 39°. Under these conditions, three parallel experiments were performed, resulting in a rectification rate of 90.35% in the mechanically harvested and compressed area and a second-season yield of 2202.64 ± 35 kg/hm². The deviation from the numerical simulation results of parameter optimization was less than 5%. These findings suggest that the designed stubble rectification device for ratoon rice can meet the requirements of stubble rectification during the first-season harvest of ratoon rice. Furthermore, it provides valuable insights for reducing harvest losses in the first season and further improving the level of mechanized harvesting for ratoon rice.

Simulation Analysis and Parameter Optimization of Residual Film Pickup Process Based on Finite Element Method

The extended duration of mulching in Xinjiang cotton fields leads to a significant decline in the tensile strength of plastic film. When recycling is in operation, the soil and the spring teeth of the machinery used can easily cause secondary damage and fracture the residual film. Establishing appropriate working parameters for recycling is essential to enhance the overall quality of collection efforts. By analyzing the motion process of a chain-tooth residual film pickup device, we identified key working parameters that significantly impact the efficiency of recycling. Employing the finite element method (FEM) and a coupled algorithm incorporating smooth particle hydrodynamics (SPH), we developed a coupled finite element model representing the interaction among spring teeth, soil, and residual film. Through simulation and analysis of the process of inserting the spring teeth into the soil to collect film, we derived the governing rules for residual film stress and deformation changes. Utilizing forward speed, rotational angular velocity, and angle of entry into the soil of the spring teeth as test factors and selecting the residual film stress and the residual film deformation as test indices, we conducted a multi-factor simulation test. We established a mathematical model correlating test factors with test indices, and the influence of each factor on the test index was analyzed. Subsequently, we optimized the working parameters of the spring teeth. The results indicated that the optimal working parameters are forward speed of 1111.11 mm/s, rotational angular velocity of 25 rad/s, and angle of entry into the soil of 30°. At these values, the average peak stress of residual film was 4.51 MPa and the height of residual film pickup was 84.48 mm. To validate the optimized the spring teeth impact on performance, field experiments were conducted with recovery rate and winding rate as test indices. The results demonstrated a 92.1% recovery rate and a 1.1% winding rate under the optimal combination of working parameters. The finite element model presented in this paper serves as a reference for designing and analyzing key components of residual film recycling machines.

The Importance of Lumbar Lordosis During Laparoscopic Trocar Entry

Study ObjectiveInvestigating the effect of lumbar lordosis on the relationship between abdominal trocar entry points and major vascular structures. DesignRetrospective cohort. SettingTertiary referral center. PatientsDistances between the skin and the aorta and inferior vena cava at the trocar entry points, both at the umbilicus and 3 cm and 5 cm superior to the umbilicus, were measured at entry angles of 90 and 45 degrees in 101 abdominal computer tomography images. InterventionsThe relationship of these values with lumbar lordosis was investigated concerning menopausal status, body mass index (BMI), and parity differences. To assess the isolated effect of lumbar lordosis, a simulated 30-degree increase in the lordosis angle was applied to the patients’ computed tomography images. The impact of this increased lumbar lordosis angle on the distances between the skin and major vessels was then evaluated at both the umbilical and supraumbilical trocar entry sites. Measurements and Main ResultsIn the tomographic images of all patients, the distances from the skin to vascular structures were measured at a 90-degree entry angle, resulting in measurements of 8.97 cm ± 2.81 at the umbilicus, 10.89 cm ± 3.02 at 3 cm above the umbilicus, and 11.36 cm ± 2.88 at 5 cm above the umbilicus. These distances exhibited significant differences between patients with BMI <30 and BMI ≥30, as well as between premenopausal and postmenopausal patients. However, at a 45-degree entry angle, vascular structures were observed in only a few patients during trocar projection, and no measurable values were determined. In the simulation, it was found that a 1-degree increase in lumbar lordosis angle resulted in a decrease of 0.272 mm ± 0.018 in the distance between the skin and vascular structures at the umbilicus, 0.425 mm ± 0.024 at 3 cm above the umbilicus, and 0.428 mm ± 0.024 at 5 cm above the umbilicus. ConclusionAn increase in the degree of lumbar lordosis reduces the distance between trocar entry points and major vascular structures. Along with other factors during Veress and trocar entry, lumbar lordosis should be carefully considered.

Research on Ship Automatic Berthing Algorithm Based on Flow Matching and Velocity Matching

Addressing the automatic berthing task for vessels, this study introduces the Flow Matching Double Section Bezier Berth Method (FM-DSB) for handling downstream and upstream berthing instructions. By considering the orientation relationship between the direction of water flow and the berth, combined with berthing modes, the algorithm determines the vessel’s entry angle into the berth and plans the berthing path using double-section Bezier curves. Effective control of vessel speed post-path determination is essential. Therefore, based on the response of vessels to propeller inputs, this study introduces the Berthing Path Velocity Matching Method (BPVM). The BPVM ensures speed matching along the berthing path through analysis of vessel acceleration and deceleration capabilities. Subsequently, simulation experiments are conducted to validate the planning algorithm for both long-distance and short-distance berthing. Furthermore, the feasibility and effectiveness of the berthing path are verified using a dual-loop path tracker based on the planned results. Experimental outcomes illustrate the adaptability of the proposed algorithm in planning berthing paths that align with vessel motion characteristics, effectively guiding vessels into berths through the designed dual-loop control system.

Research of Slamming Load Characteristics during Trans-Media Aircraft Entry into Water

The trans-media aircraft water entry process generates strong slamming loads that will seriously affect the stability and safety of the aircraft. To address this problem, we design a fixed-wing aircraft configuration and employ numerical simulations with the volume of fluid (VOF) multiphase flow model, standard k-epsilon turbulence model, and dynamic mesh technique. We explore the characteristics of aircraft subjected to bang loads under different conditions. The results show the following: the pressure load on the aircraft surface increases with higher water entry velocity; larger entry angles lead to more drastic changes in the aircraft’s drag coefficient, demonstrating strong nonlinear characteristics; the greater the angle of attack into the water, the greater the pressure load on the root underneath the wing, with little effect on the pressure load on the head; and the water entry drag coefficient and average pressure load follow an increasing order of conical head, hemispherical head, and flat head. These findings provide theoretical references for studying the load characteristics during trans-media water entry of various flying bodies and optimizing fuselage structural strength.

Exploring the Intricacies of Pancreatic Duct Tributaries: Variations in Length, Angle of Entry, and Alternating Patterns in Human Cadavers by Dissection

Background: The pancreatic duct system plays a pivotal role in human physiology, facilitating the transport of digestive enzymes and secretions essential for gastrointestinal function. While anatomists have extensively investigated the pancreas's ductal network, the intricacies of pancreatic duct tributaries, including variations in length, angle of entry, and alternating patterns, have continued to captivate scientific inquiry. Aim: To find out the variations in length, angle of entry, and alternating patterns of pancreatic duct tributaries, and discuss the potential clinical implications of our discoveries. Materials and Methods: This study, conducted on 50 human cadavers (comprising 35 perinates and 15 adults), aimed to comprehensively explore the complexities of pancreatic duct tributaries through meticulous dissection. Results: Our research unveiled the following key findings: Variations in Length and Angle of Entry: We observed a remarkable diversity in the number and length of tributaries that join the main pancreatic duct. Additionally, the entry angle exhibited substantial variation, with right-angled tributaries prevalent in 70% of specimens and acute angles in 30%. Understanding these anatomical nuances is crucial for surgical procedures to mitigate inadvertent ductal injury. Alternating and Herringbone Patterns: In 98% of specimens, tributaries alternated between superior and inferior positions along the main pancreatic duct. This alternating pattern may influence the flow of pancreatic secretions and the pathogenesis of pancreatic diseases. In contrast, the rare Herringbone pattern was observed in only 2% of cases, highlighting the unique nature of this anatomical variant. Conclusion: This study contributes valuable insights into the intricate world of pancreatic duct tributaries. By elucidating their anatomy and characteristics, we enhance the safety and efficacy of clinical interventions and expand our understanding of pancreatic physiology and pathology. Further research may delve into the functional implications of these anatomical variations, paving the way for advancements in pancreatic healthcare. KEYWORDS: Pancreatic Duct Tributaries, Anatomical Variations, Pancreatic Surgery, Pancreatic Physiology, Dissection, Herring Bone Pattern, Gastrointestinal Function.

Basketball Fatigue Impact on Kinematic Parameters and 3-Point Shooting Accuracy: Insights across Players' Positions and Cardiorespiratory Fitness Associations of High-Level Players.

This study investigated the impact of basketball-induced fatigue on 3-point jump shooting accuracy, the ball's entry angle (EA) into the hoop, shot release time (RT), their relationship with player positions in high-level basketball, and the correlation between cardiorespiratory fitness markers and potential shooting performance changes. Guards (n = 13), forwards (n = 13), and centers (n = 12) underwent physiological assessments. Sequentially, they performed 15 jump shots (PRE), a basketball exercise simulation (BEST) involving 24 × 30 s circuit activities, and a repeated shooting test (POST). The study design was double-blind. The results revealed significant differences (p ≤ 0.05) in RT, EA, and successful shots (SSs) between PRE and POST in each group. The percentage changes from PRE to POST conditions across guards, forwards, and centers were for RT: 25.34% [95%CI: 1.7-48.98], 19.73% [95%CI: -1.9-41.36], 14.95% [95%CI: -5.23-35.13]; for EA: -3.89% [95%CI: -14.82-7.04], -3.13% [95%CI: -12.9-6.64], -3.47% [95%CI: -14.19-7.25]; and for SS: -14.42% [95%CI: -36.5-7.66], -16.76% [95%CI: -40.81-7.29], -19.44% [95%CI: -46.7-7.82], respectively. Post-test differences (p ≤ 0.05) highlighted greater fatigue impact on RT, EA, and SS from guards to centers. Additionally, significant correlations (p ≤ 0.05) were found between the ventilatory threshold, mean HR during BEST, and changes in RT, EA, and SS. This study highlights the substantial impact of basketball-induced fatigue on 3-point shooting parameters across player positions and the interplay with cardiorespiratory factors post-fatigue. Tailored training, considering heart rate, is crucial to optimizing shooting performance.

Automated angular measurement for puncture angle using a computer-aided method in ultrasound-guided peripheral insertion.

Ultrasound guidance has become the gold standard for obtaining vascular access. Angle information, which indicates the entry angle of the needle into the vein, is required to ensure puncture success. Although various image processing-based methods, such as deep learning, have recently been applied to improve needle visibility, these methods have limitations, in that the puncture angle to the target organ is not measured. We aim to detect the target vessel and puncture needle and to derive the puncture angle by combining deep learning and conventional image processing methods such as the Hough transform. Median cubital vein US images were obtained from 20 healthy volunteers, and images of simulated blood vessels and needles were obtained during the puncture of a simulated blood vessel in four phantoms. The U-Net architecture was used to segment images of blood vessels and needles, and various image processing methods were employed to automatically measure angles. The experimental results indicated that the mean dice coefficients of median cubital veins, simulated blood vessels, and needles were 0.826, 0.931, and 0.773, respectively. The quantitative results of angular measurement showed good agreement between the expert and automatic measurements of the puncture angle with 0.847 correlations. Our findings indicate that the proposed method achieves extremely high segmentation accuracy and automated angular measurements. The proposed method reduces the variability and time required in manual angle measurements and presents the possibility where the operator can concentrate on delicate techniques related to the direction of the needle.

Using Machine-Learning Technology to Implement a Nonhardware and Inexpensive Posture Detection System for Analyzing Body Posture Angles in Front Crawl Swimming

&lt;p&gt;Swimming is a sport that relies heavily on motor skills. Inability to maintain adequate bodily balance in water prevents swimmers from remaining afloat and propelling themselves. Due to the difficulty of attaching reflective stickers or LED (light-emitting diode) emitters to the body while adjusting the swimming posture, it is not possible to capture the posture like during a bicycle fitting; the refraction of water also affects the detection of the body&amp;rsquo;s posture. Addressing the shortcomings, this study developed a low-cost nonhardware posture detection system based on machine-learning models in MediaPipe. The system provides real-time and post analyses of posture angles and posture lines during front crawl swimming, thereby facilitating observation of the relationship between angle at which the arm enters the water and the body horizon. Two participants practicing front crawl were invited to test the proposed system. The experimental results confirmed that the proposed system provides effective detection and analyses of posture lines and angles in swimmers. The study also proposed the algorithm for optimizing posture angle detection to solve the problems of posture line distortion and angle calculation errors that arise when MediaPipe was used to detect a human skeleton above a water line. The system does not require the installation of hardware and is inexpensive to deploy, and it can be widely applied in front crawl swimming lessons to help learners adjust their arm&amp;rsquo;s entry angle and body horizon to reduce forward drag and increase speed.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;