Entry Angle Research Articles

The Contribution of Ball Launching and Ring Entrance Angle Variables in 3 points Jump Shot in Basketball

The research aimed at identifying the values of ball launch and ring entrance angle and relations among them as well as identifying the contribution of ball launch and angle variables in 3 point jump in basketball. The researchers hypothesized statistical relation between ball launch and entrance angle. They used the descriptive method on (10) basketball players best known for their 3 point jump shot. Each player is given (10) attempts and only attempts with a larger entrance angle in recorded. The results showed that the height of ball launch players an integral role in decreasing entrance angle as well as ball launch angle did not correlate with the entrance angle. Finally, ball launch variables have no effect or contribution on ball entrance angle.

Road to automating robotic suturing skills assessment: Battling mislabeling of the ground truth

ObjectiveTo automate surgeon skills evaluation using robotic instrument kinematic data. Additionally, to implement an unsupervised mislabeling detection algorithm to identify potentially mislabeled samples that can be removed to improve model performance. MethodsVideo recordings and instrument kinematic data were derived from suturing exercises completed on the Mimic FlexVR robotic simulator. A structured human consensus-building process was developed to determine Robotic Anastomosis Competency Evaluation technical scores across 3 human graders. A 2-layer long short-term memory–based classification model used instrument kinematic data to automate suturing skills assessment. An unsupervised label analyzer (NoiseRank) was used to identify potential mislabeling of skills data. Performance of the long short-term memory model’s technical skill score prediction was measured by best area under the curve over the training runs. NoiseRank outputted a ranked list of rated skills assessments based on likelihood of mislabeling. Results22 surgeons performed 226 suturing attempts, which were broken down into 1,404 individual skill assessment points. Automation of needle entry angle, needle driving, and needle withdrawal technical skill scores performed better (area under the curve 0.698–0.705) than needle positioning (0.532) at baseline using all available data. Potential mislabels were subsequently identified by NoiseRank and removed, improving model performance across all domains (area under the curve 0.551–0.766). ConclusionUsing ground truth labels from human graders and robotic instrument kinematic data, machine learning models have automated assessment of detailed suturing technical skills with good performance. Further, an unsupervised mislabeling detection algorithm projected mislabeled data, allowing for their removal and subsequent improvement of model performance.

Discrete element method optimisation of a scraper to remove soil from ridges formed to cold-proof grapevines

A scraper is the most commonly used tool for removing soil from ridges used to cold-proof vines grown in northern China. It can have different complex shapes and its structure and working parameters are vital for effectively removal soil and saving energy. In this study, the interaction between the scraper and the soil was simulated using discrete element method (DEM) simulation, and a calibrated DEM model was developed to simulate soil removal of the scraper. The scraper with different profiles (straight-line, arc, and parabola), different entry angle (δ) and different wing opening angle (θ) were simulated and analysed at various forward speeds (v) in DEM model. The draught force and bilateral soil throw width of the scraper were used to evaluate the effect of soil removal. The DEM model was verified by field experiment, and the draught force and bilateral soil throw width in DEM simulation were compared with the field experiment and the relative errors were 5.97% and 2.88%, respectively. This shows that the DEM model can accurately simulate and optimise the scraper. In order to achieve the best soil removal effect, that is to minimise the draught force and to maximise the bilateral soil throw width, the scraper with arc profile was selected and the optimised values of δ, θ and v were 60°, 86° and 0.6 m s−1, respectively. The corresponding optimal values of draught force and bilateral soil throw width were 58.55 N and 1223 mm, respectively, and based on the optimized parameters, the optimisation results were verified.

PD58-03 ASSOCIATIONS IN TECHNICAL SKILL BETWEEN SUCCESSIVE SUTURING SUB-STEPS

You have accessJournal of UrologySurgical Technology & Simulation: Training & Skills Assessment (PD58)1 Sep 2021PD58-03 ASSOCIATIONS IN TECHNICAL SKILL BETWEEN SUCCESSIVE SUTURING SUB-STEPS Daniel I. Sanford, Balint Der, Taseen F. Haque, Runzhuo Ma, Ryan Hakim, Jessica H. Nguyen, Steven Cen, and Andrew J. Hung Daniel I. SanfordDaniel I. Sanford More articles by this author , Balint DerBalint Der More articles by this author , Taseen F. HaqueTaseen F. Haque More articles by this author , Runzhuo MaRunzhuo Ma More articles by this author , Ryan HakimRyan Hakim More articles by this author , Jessica H. NguyenJessica H. Nguyen More articles by this author , Steven CenSteven Cen More articles by this author , and Andrew J. HungAndrew J. Hung More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002092.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Intra-operative surgeon performance has been associated with post-operative clinical outcomes and complications. Specifically, our prior work found that suturing performance is linked to urinary continence recovery following robot-assisted radical prostatectomy. Herein, we analyze how the successive sub-steps of suturing are interrelated in terms of technical skill. METHODS: 22 surgeons completed a suturing exercise three times on the MimicTM Flex VR simulator. Video recordings were deidentified and assigned technical skill scores by three blinded, independent graders for each sub-step of suturing (needle positioning (1), needle entry angle (2), needle driving (3) and needle withdrawal (4)). Assessments of suturing technical skill were derived from the clinically validated assessment tool Robotic Anastomosis Competency Evaluation (RACE). Hierarchical Poisson regression with Generalized Estimating Equation was used to examine the association between exposure and outcome by adopting the nested data structure of multiple training exercises within each trainee. We have adjusted potential confounders and tested effect modifiers in the Poisson model. RESULTS: Training (n=7, median caseload 0 (IQR 0-8)) and expert (n=15, 300 (165-750)) surgeons completed 428 individual suturing positions. 1,670 technical skill assessments were made. Ideal technical skill scores between needle positioning (1) and needle entry angle (2) (RR 1.12, p=0.05), needle entry angle (2) and needle withdrawal (4) (RR 1.27, p=0.03), and needle driving (3) and needle withdrawal (4) (RR 1.30, p=0.03) were found to be significantly positively associated with each other (Figure 1). With multivariate analysis, taking needle positioning score into account, a positive association for ideal technical skill scores between entry angle (2) and needle withdrawal (4) was found (RR 1.40, p<0.01). CONCLUSIONS: Our study found significant associations in the technical skill required for completing successive sub-steps of the suturing process. Suturing is a chain of events and the success and efficiency of the entire process relies on proper technique in each sequential step. Together with the known association between technical skill and clinical outcomes, training surgeons should focus on not just the overall suturing process, but each sub-step involved. Source of Funding: National Institutes of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award K23EB026493 © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e1017-e1017 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Daniel I. Sanford More articles by this author Balint Der More articles by this author Taseen F. Haque More articles by this author Runzhuo Ma More articles by this author Ryan Hakim More articles by this author Jessica H. Nguyen More articles by this author Steven Cen More articles by this author Andrew J. Hung More articles by this author Expand All Advertisement Loading ...

Evaluation of the Course of Inferior Alveolar Canal and its Relation to Anatomical Factors on Digital Panoramic Radiographs.

Statement of the Problem: The inferior alveolar canal (IAC) is a bony canal that starts from mandibular foramen at the inner surface of the mandibular ramus and extends along the ramus and body of mandibular bone in forward and downward directions to the mental foramen. Inside the mandibular canal, there are lower alveolar artery and a nerve with the same name. Understanding the anatomical details of the lower alveolar canal, including position, pathway and morphology to prevent complications in surgical procedures in the lower jaw such as mandibular impacted molar surgeries, mandibular nerve block injection, or even root canal treatment of mandibular teeth is important. Purpose: The purpose of this study was to investigate the course and direction of IAC in mandibular bone and its relation to anatomical factors such as gonial angle and location of entrance of IAC in the mandibular ramus.Materials and Method: This cross-sectional study evaluated a sample of 280 digital panoramic images. All samples were Iranian. The pattern and direction of the IACs were recorded according to age and gender and the relation of these patterns to the gonial angle of mandible and the entry point of the IAC in mandibular ramus were evaluated.Results: The results showed that the course of canal, the entrance point of the canal and the gonial angle were the same between different age groups and between two genders. There was no significant relation between the course of canal and the two anatomical variables mentioned (p> 0.05).Conclusion: Considering the increasing frequency of implant surgeries and presence of different courses of the mandibular canal and concerning the important complications such as paresthesia caused by damage to the mandibular nerve, panoramic radiography is necessary before any surgery in this area to avoid unwanted injuries to the neurovascular system if other advanced modalities are not available.

PD58-08 AUTOMATING SUTURING SKILLS ASSESSMENT WITH A LIMITED SURGEON DATASET: META LEARNING

You have accessJournal of UrologySurgical Technology & Simulation: Training & Skills Assessment (PD58)1 Sep 2021PD58-08 AUTOMATING SUTURING SKILLS ASSESSMENT WITH A LIMITED SURGEON DATASET: META LEARNING Andrew J. Hung, Sirisha Rambhatla, Daniel I. Sanford, Nilay Pachauri, Jessica H. Nguyen, and Yan Liu Andrew J. HungAndrew J. Hung More articles by this author , Sirisha RambhatlaSirisha Rambhatla More articles by this author , Daniel I. SanfordDaniel I. Sanford More articles by this author , Nilay PachauriNilay Pachauri More articles by this author , Jessica H. NguyenJessica H. Nguyen More articles by this author , and Yan LiuYan Liu More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002092.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Automating technical skills assessment with machine learning models can revolutionize how we credential surgeons, and it can identify critical errors before they become patient complications. Common to many machine learning challenges, having limited training data can prevent our ability to accurately project skills assessment for a wide population of surgeons. Herein, we utilized meta learning, a specialized form of machine learning, to learn from a limited set of surgeons, and adapt learned representations to new additional surgeons. METHODS: Training and faculty surgeons completed a suturing simulation task on the Mimic Flex VR robotic simulator. Video and kinematic data (instrument XYZ coordinates and pose) were collected. Three human raters utilized the video and a suturing assessment tool to provide ground truth labels for skill domains. Kinematic data was utilized by two baseline models and the proposed Meta learning model to project skills assessment. For each skill domain, surgeons with minimum two ideal and non-ideal performance examples were included. Data from five surgeons were randomly selected for the test set, remainder was utilized for training. Three two-layer LSTM-based models projected skills assessment: No-customization, Fine-tune (customized the base model for new surgeons), and Meta learning (not only customized predictions, but also updated the base model thereby maximizing learning). Best area under the curve (AUC) metric across epochs was used to assess performance. RESULTS: In total, 21 surgeons contributed performance data for analysis. 16 surgeons contributed examples to Needle positioning scoring, 19 to Needle entry angle, 20 to Needle driving, and 20 to Needle withdraw. For all skill domains, Meta learning achieved the highest performance in projecting the ground truth labels (AUC = 0.72-0.88) (Table). In all skill domains, Meta learning outperformed both the Fine-tune and No customization models. Fine-tune outperformed No customization in all domains, except for Needle withdrawal. CONCLUSIONS: Our initial experiments with Meta learning demonstrate that it can augment model performance in automated suturing skill assessment with a limited surgeon dataset by applying learned patterns to new additional surgeons. Overall, Meta learning projection results are very robust. Source of Funding: Research reported in this publication was supported in part by the National Institute Of Biomedical Imaging And Bioengineering of the National Institutes of Health under Award Number K23EB026493. © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e1019-e1020 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Andrew J. Hung More articles by this author Sirisha Rambhatla More articles by this author Daniel I. Sanford More articles by this author Nilay Pachauri More articles by this author Jessica H. Nguyen More articles by this author Yan Liu More articles by this author Expand All Advertisement Loading ...

CFD МОДЕЛЮВАННЯ АЕРОДИНАМІЧНОГО ПОТОКУ У ВІТРЯНІЙ ТУРБІНІ З ВЕРТИКАЛЬНОЮ ВІССЮ ОБЕРТАННЯ І КОНЦЕНТРАТОРОМ ВІТРОВОГО ПОТОКУ

In order to improve the aerodynamic characteristics by increasing the energy of the wind flow of wind turbines with a vertical rotational axis, a special device - wind flow concentrator was proposed. The concentrator contains channels with a curved contour, which are installed around the rotor. To study the hydrodynamic parameters of the wind flows concentrator depending on the ratio between the input and output geometric characteristics of the channels, as well as the angles of entry and exit methods of mathematical modeling are used. Based on the method of quadratic rotational design of orthogonal combinations, using three-dimensional numerical simulation, the aerodynamic characteristics of the wind flow concentrator for a vertical axis wind turbine were investigated.

CT‐guided percutaneous epicardial access for ventricular tachycardia ablation: A proof‐of‐concept study

The objective of this study was to evaluate the safety and efficacy of preprocedural computed tomography (CT) to guide percutaneous epicardial puncture for catheter ablation of ventricular tachycardia. A preprocedural CT was used to plan the site, angle, and depth of needle insertion during epicardial access in 10 consecutive patients undergoing ventricular tachycardia (VT) ablation. Adjacent structures (right ventricle, diaphragm, liver, colon, internal mammary artery) were visualized and the course of the needle was planned avoiding these structures. During epicardial access, a protractor was used to guide the angle of needle entry into the subxiphoid space. Postprocedural CT was performed to calculate the deviation between the planned and executed access and to assess for any collateral damage. Percutaneous epicardial access was obtained successfully in all the patients using anterior (n = 4) and inferior (n = 6) approaches. The planned site and angle of puncture was more caudal (2.9 ± 0.9 vs. 3.7 ± 0.7 cm, p = .021) and acute (61.7 ± 5.8 vs. 49.0 ± 5.4°, p = .011) for an anterior approach compared to an inferior approach, respectively. Postprocedure CT revealed minimal deviation of the puncture site (5.4 ± 1.0 mm), angle (5.4 ± 1.2°), and length of needle insertion (0.5 ± 0.2 cm). With regard to the site of entry in the pericardial space, there was a deviation of 5.9 ± 1.1, 6.1 ± 1.1, and 5.8 ± 1.4 mm in the x, y, and z dimensions, respectively. In eight patients with minimal deviation between planned and executed access, there was no collateral injury to adjacent viscera or vessels. In two patients with increased deviation of angle and length of needle insertion, there was entry through the diaphragm during inferior access. Utilizing pre-procedural CT planning may aid in the success and safety of percutaneous epicardial access during VT ablation.

Mechanical characterization of flat faced deformable AUV during water entry impact considering the hydroelastic effects

In this paper, the dynamic behavior of flat faced deformable autonomous underwater vehicle (AUV) subjected to hydroelastic water entry impact is numerically investigated by using Arbitrary Lagrangian Eulerian (ALE) method. The experiments on the flat faced AUV head section of 200 mm diameter are carried out in a water tank to validate the numerical model by comparing the impact accelerations and underwater cavity evolution by using accelerometers and high speed cameras. Then, the effect of hydroelasticity is numerically investigated by comparing the impact characteristics of rigid and deformable AUV with different rigidities. It is revealed that the hydroelastic effect increases with the decrease in the rigidity of the structure. Mechanical behavior of deformable AUV of various rigidities under the initial conditions of same velocity, same kinetic energy and same mass is examined. The influence of various initial conditions on the hydrodynamic load, impact pressure and effective strain for deformable AUV are discussed. The influence of the water entry angle and impact velocity on the semi-rigid and deformable AUVs are also studied. It is found that the effective strain increases exponentially with the increase in impact velocity and entry angle for deformable AUV, however, semi-rigid AUV exhibit linear strain behavior. Numerical conclusions drawn from this study are vital in selecting the rigidity of AUV and highlighted the influence of hydroelasticity for flat faced AUVs. Additionally, the results obtained in this study can be beneficial for the structural design of high speed air launched AUVs.

Optimization of a Pelton impeller geometry for particulate flow using numerical simulation

The aim of this work is to develop a methodology for Pelton turbines performance improvement using reverse engineering, parametric design and CFD analysis. The methodology was applied on a real turbine from the company ELEPCO S.A. Initial geometry was obtained using resin and plaster mold, 3D scanning was applied to acquire a point cloud. The parametric CAD model was obtained by using Python along with parametric design tools from Autodesk Inventor. The optimization of the model was achieved by varying the entry and exit angles of the bucket. Numerical simulation was executed using ANSYS CFX with k-ω SST turbulence model.

Investigation on damage reduction method by varying cutting angles in the cutting process of rectangular Nomex honeycomb core

Nomex honeycomb component is a typical weak rigid structure, leading to various damages during cutting operation. In this paper, the effects of cutting angles, entrance angle and engagement angle, on cutting quality were analyzed by focusing on the cell wall deformation, the cutter-workpiece interaction and the thin-walled cell geometry. A damage reduction method was proposed by controlling the range of the cutting angles. Experiments were conducted to verify the damage reduction method by cutting rectangular Nomex honeycomb core using multi-teeth disc cutters. The results showed that the method has a remarkable effect on the characteristics and distributions of damages by varying cutting angles: (a) the experimental damage-prone range of entrance angle is 55° ~ 75°, and an entrance angle near to 0° or 180° is more beneficial to damage reduction; (b) when engagement angle is smaller than 90°, there will be no visible tear damage; (c) up-cutting direction that makes entrance angle larger than 80° and engagement angle smaller than 90° is effective for damage reduction, leading the damage size is reduced by at least 40%; (d) engagement angle decreases as increasing cutting edge inclination so that the damage size can be further reduced by at least 70%.

High efficiency calculation of cutter-workpiece engagement in five-axis milling using distance fields and envelope theory

Cutter-workpiece engagement (CWE) is fundamental to the process mechanics and dynamics modeling. Due to the variation of the feed directions in five-axis milling of freeform surfaces, the instantaneous CWE is complex and time-varying. Therefore, for the industrial part milling process which contains tremendous cutter locations, how to calculate the CWE efficiently and accurately remains a challenge. In this paper, a high efficiency method for CWE calculation in five-axis milling based on the distance field and envelope theory is proposed. In the geometry modeling and milling simulation, workpiece surfaces are modeled using sampled distance fields stored in a well-designed octree data structure for efficient memory usage. The inverted trajectory method is used to calculate the tool swept volume, which is subtracted from the in-process workpiece by performing three-stage intersection detection and accelerated Boolean operation. As for the CWE extraction at a specific cutter location, the feasible contact arcs derived from the cutter surfaces based on the envelop theory are used as geometry primitives to intersect the in-process workpiece. A new segment-evaluation algorithm is offered to find the intersection points of each feasible contact arc with the workpiece surfaces. Finally, the CWE diagram is obtained by combining the entry and exit immersion angles of the engagement arcs at each axis height. The feasibility of the proposed method for industrial applications is evidenced by two case studies conducted on a developed virtual machining simulator. The results of the comparison with the B-rep based method indicate that the proposed method is more efficient while providing good accuracy.

Numerical simulation of cavitation characteristics in high speed water entry of head-jetting underwater vehicle

Autonomous underwater vehicle will be subjected to a huge impact load during high speed water entry, which will damage the structure and the internal instruments of the vehicle. Therefore, it is of great significance to study the buffer mechanism of the vehicle during the process of water-entry. In this paper, a kind of head-jetting device with disk cavitation is used. The complex cavitation forms, under the three-phase coupling of gas, liquid and solid, in the water entry process of the vehicle on which the device is installed. In this paper, the numerical simulation of high-speed water entry of the vehicle equipped with head jet device is carried out. Through the analysis of water entry cavitation under typical working conditions, the following conclusions are obtained. After the installation of head jet device, the water entry cavity of the vehicle changes gradually from cone to spindle shape. The air jet, compared with that without jet, can promote the formation of water inlet supercavitation, decrease the interaction area between the vehicle and water, and reduce the impact load during water entry. At the same water entry depth, the diameter of cavitation increases with the amount of air jet. The water entry velocity has a great influence on the difference of cavitation shape. The water entry depth closure phenomenon, when the water entry velocity is less than 100 m/s, can be observed in the depth of 3.5 times of the projectile length. The water entry angle has a significant effect on the cavitation shape. The cavity shows obvious asymmetry when the vehicle slants into the water, and the diameter and length of the bubbles decrease with the increase of the water entry angle. The research content of this paper provides technical support for the engineering practice of high-speed water entry and load reduction, and the conclusions are of great significance in related fields.

Comparison of Frame-Based Versus Frameless Image-Guided Intracranial Stereotactic Brain Biopsy: A Retrospective Analysis of Safety and Efficacy

A definitive diagnosis of brain lesions not amenable to surgery is mainly made by stereotactic needle biopsy. The diagnostic yield and safety of the frameless versus frame-based image-guided stereotactic techniques is unclear. Our objective was to evaluate the safety and accuracy of frameless versus frame-based stereotactic brain biopsy techniques. A total of 278 patients (153 men; mean age: 65.5 years) with intra-axial brain lesions underwent frame-based (n= 148) or frameless image-guided stereotactic brain biopsy (n= 130) using a minimally invasive twist drill technique during 2010-2016 at Sheba Medical Center. Demographic, imaging, and clinical data were retrospectively analyzed. The diagnostic yield (>90%) did not differ significantly between groups. Overall morbidity (6.8% vs. 8.5%), incidence of permanent neurologic deficits (2.1% vs. 1.6%), mortality rate (0.7% vs. 0.8%), and postoperative computed tomography-detected asymptomatic (14.2% vs. 16.1%) and symptomatic (2.0% vs. 1.6%) bleeding also did not differ significantly between the frame-based and frameless cohorts, respectively. The diagnostic yield and complication rates related to the biopsy technique were not significantly associated with sex, age, entry angle to the skull and skull thickness, lesion location or depth, or radiologic characteristics. Diagnostic yield was significantly associated with the mean lesion volume. Smaller lesions were less diagnostic than larger lesions in both techniques (P= 0.043 frame-based and P= 0.048 frameless). The frameless biopsy technique is as efficient as the frame-based brain biopsy technique with a low complication rate. Lesion volume was the only predictive factor of diagnostic yield. The minimally invasive twist drill technique is safe and efficient.

Accuracy and Safety of Image-Guided Freehand Pin Placement in Canine Cadaveric Vertebrae

AbstractObjective The aim of this study was to validate an imaging technique for evaluation of spinal surgery accuracy and to establish accuracy and safety of freehand technique in the thoracolumbar spine of large breed dogs.Study Design After thoracolumbar spine computed tomography (CT), 26 drilling corridors were planned then drilled to receive 3.2 mm positive profile pins using a freehand technique. After pin removal, CT was repeated. All entry points, exit points and angles of the preoperative planned trajectories were compared with postoperative ones using an image registration and fusion technique by three observers. Corridor coordinates for entry and exit points were evaluated in three dimensions and angles were measured in one plane. Intraclass correlation coefficient (ICC) was used to establish the imaging technique reliability and descriptive statistics were used to report on the freehand technique accuracy. Safety was evaluated using a vertebral cortical breach grading scheme.Results Intraclass correlation coefficient for the entry points, exit points and angle were 0.79, 0.96 and 0.92 respectively. Mean deviations for the entry points, exit points and angle were 3.1 mm, 6.3 mm and 7.6 degrees respectively. Maximum deviations were 6.3 mm, 11.0 mm and 16.4 degrees. Most deviations were lateral and caudal. All corridors were judged as safe.Conclusion The imaging technique reliability was good to excellent to study spinal surgery accuracy. Implant deviations should be anticipated when planning stabilization surgery in large breed dogs using the freehand-guided technique.

Grounding of Design and Technology Parameters of Combined Coulter Furrow Opener of Precision Seed Drill

A formation of a seedbed is an important step during seed sowing process. A quality of seedbed formation influences on seeds distribution along both a row and a depth and is triggering the opportunity to obtain early and even sprouts. The design of the furrow opener is the main element that has a direct impact on the qualitative formation of seedbed and technological parameters of coulter operation. During the research, there has been analyzed the modern construction of precision seed drills coulters and specified advantages and disadvantages of their operation. It has been established that the most advanced are coulters having a working section with a combined angle (sharp and obtuse) of entry into the soil. The attained results afforded to develop an improved design of the coulter furrow opener of the precision seed drill. There was brought forward a combined wedge furrow opener, the upper part of which has a working section with a sharp angle of entry into the soil, lower - and compactor, located in the rear part of the furrow opener, which forms seedbed has a working surface with an obtuse angle of entry into the soil. There were obtained analytical dependences targeted to determine the main structural and technological parameters of the operating elements of a combined coulter furrow opener which is used to seed cultivated crops: the angles of entry into the soil of the upper and lower part of the furrow opener, compactor in the rolling plane and the angle of tip of the furrow opener in the horizontal plane.

Experimental investigation of the microbubble generation using a venturi-type bubble generator

This experimental study investigated how changes in the water flow rate affected the number and size of microbubbles using venturi with equal entry and exit angles of 30°. The water flow rate ranged between 10 and 18 m3/h . Photos of microbubbles were taken with a digital camera in a visualized section that was specifically installed to store a certain amount of water to measure microbubble size and the number of microbubbles. The experimental results indicated that when the water flow rate increased, the airflow rate also increased. The microbubble size tended to decrease when the water flow rate increased; the sizes obtained were in the range of 50–130μm. The amount of air bubbles tended to increase when the water flow rate increased.

Does fatigue affect the kinematics of shooting in female basketball?

ABSTRACT Few studies investigated the influence of fatigue on the change of kinematic parameters in basketball shooting regarding female players. This study aimed to determine the difference of kinematics in basketball jump shot between non-fatigue and fatigue conditions. Thirty-two professional female basketball players volunteered to take part in the study (age: 22.11 ± 4.92 years; height: 173.99 ± 7.06 cm; weight: 67.89 ± 5.65 kg). 3D motion analysis using an inertial suit and a smart ball were performed for measuring the kinematic parameters. The results demonstrated that there were no significant differences in angular velocity of ankle, knee and hip joints. Conversely, differences in angular velocity of elbow (p = 0.036) and wrist (p = 0.002) were detected. In addition, the results showed that the release height and entry angle of the ball significantly decreased in fatigue condition, suggesting that coaches need to include in the training process exercise that is similar in terms of fatigue and performance to the situational condition during the game as these two variables play an important role in the determination of shooting efficiency.

Burrow characteristics and ecological significance of Marmota himalayana in the northeastern Qinghai-Tibetan Plateau.

Burrows provide burrowing animals with a place to hibernate, reproduce, and avoid predators and harsh weather conditions and thus have a vital impact on their survival. However, the general physical characteristics and ecological functions of Marmota himalayana burrows as well as whether there are differences in burrow traits under different terrains (e.g., sunny slopes, shady slopes, and flat areas) are not well understood. From July to August 2019 (warm season), we used unmanned aerial vehicles to fly at low altitudes and slow speeds to locate 131 M. himalayana burrows (45 on shaded slopes, 51 on sunny slopes, and 35 on flat areas) in the northeastern Qinghai‐Tibetan Plateau region. We then measured the physical characteristics (burrow density, entrance size, first tunnel length, volume, orientation, and plant characteristics near the burrow entrance) of these burrows on site. We found that terrain had a substantial influence on burrow density, orientation, and entrance size and on the angle of the burrow entrance; species richness had a substantial impact on path density and tunnel volume. The physical parameters of the M. himalayana burrows showed that they function to protect the marmots from natural enemies and bad weather, provide good drainage, and maintain a stable microclimate around the entrance. We discuss the ability of burrowing animals (e.g., M. himalayana) to adapt to the external environment based on their burrow characteristics.

Numerical research on the high-speed water entry trajectories of AUVs with asymmetric nose shapes

During the water entry process, autonomous underwater vehicles (AUVs) take a long time to reach a horizontal attitude. To reduce the time and distance required to adjust the attitude, an AUV with an asymmetric nose shape is proposed in this paper. A numerical model based on the volume of fluid (VOF) method is established to describe the cavity and trajectory characteristics of an AUV with a high-speed water entry. Since the velocity of the AUV impacting the water surface is greater than 0.3 Ma, the Tait equation is used to describe the compressibility effects in water, and the air phase is modelled as an ideal gas. The simulation results, such as cavitation shape and velocity, are compared with the experimental data from an earlier study. Good comparative results reveal the accuracy and performance of the employed numerical method. Subsequently, the computational fluid dynamics (CFD) code Fluent is used to simulate and analyse the variations in the trajectory characteristics with different water entry velocities, water entry angles, nose shapes and rudder deflection angles. The results obtained in this study can provide a good guideline for the trajectory control and nose shape design of an AUV.