Motion Angle Research Articles

Biomechanical characterization of different rope skipping movements based on three-dimensional motion capture and electromyographic signal acquisition

Rope skipping is becoming a nationally popular sport with recreational, fitness and competitive attributes. However, poorly accomplished movements during the sport may not yield the best results and may even result in injuries. Therefore, the study used 3D motion capture and electromyographic signal acquisition for biomechanical characterization. It analyzed the human joint angles, angular velocities, muscle activation level, and muscle contribution rate in comparison when performing different rope skipping movements. The experimental results showed that the total duration of single movement was higher in the experimental group than in the control group. The average movement angle of the wrist joint in the pre-swing stage was greater for single shake than for single double shake, with the angle ranges of 116°–168° and 107°–172°, respectively. The wrist joint angular velocity of single double shake changed more gently, and the angular velocity of double shake was larger than that of single shake, with a difference of 141°. In the single-shake pre-swing stage, the activation of the trapezius and deltoid was much higher than that of the other muscles, 65% and 66%, respectively. The buffering stage contributed the most to the deltoid, with 23%, 21%, 24%, and 23% for the individual movements, respectively. As a result, the experimental group’s rope skipping movements were completed more standardized, with lower free heights and better cushioning, reducing the risk of injury. The method used in the study can effectively biomechanically characterize human joints and muscles during rope skipping and improve the science and rationality of the rope skipping movement.

Shooting Simulator “Inhibitor”: Special Effect Mathematical Support of Target Behaviour

Mathematical support and algorithms for implementing special effects oftarget active behavior and local subjects along with result analysis of performing exercise scenario for the optical-electronic shooting simulator «Inhibitor» developed at Institute of mechanics UdmFRC UB RAS and at Computer facilities department of Kalashnikov ISTU jointly with JSC «Kalashnikov» Concern», is described. A tactical and technical task is given for displaying wind-dependent local objects and fumes, to provide the realism of the targetbehavior (motion angles, defeats, return fire, evading close misses, occurrence, crawling, etc.), andarmored vehicleburning. In addition, the manager must receive complete information about the course of firing (time of firing and damage with respect totarget materialization, number of shots and errors, sight adjustment, points on target No. 4, etc.) and assess each student with control onexercise completion (magazine - shutter - fuse). It is necessary to calculate the aiming point at the moment of shooting and apply the projection of the rear sight and front sight to the target for each shot in order to control the grip, hold, aim and smooth descent skills. Theconducted studies of chromatic aberrations of special effects revealed factors affecting distortions and showed that the target situation meets the TTT requirements. The targetrealism with motion phases and angles, defeat (fall or burning), evasion of near misses, occurrence and return fire and reaction to the wind of local objects, as well as the completeness of operational informing of the leader was confirmed by military acceptance. The literature review showed the prospects for further research and development of electronic shooting simulators due to the improvement of computing tools and the development of software libraries in order to increase the accuracy of behavior simulation of the target environment and analyzing shooting results. It is necessary to expand the possibilities of special effectrealism of goals and reduce the cost, and, therefore, increase the competitiveness of electronic shooting simulatorsconstantly.

Effect of Thai Yoga Exercise for Reducing Pain and Improve Functional Disability in Patients with Text Neck Syndrome: A Randomized Controlled Trial

Text neck syndrome (TNS) is prevalent among mobile users, and exercise is a simple, non-invasive approach, for treating chronic neck pain. Research on Thai yoga (TY) exercise to relieve or reduce neck and shoulder pain in people with TNS is still limited. This study aimed to investigate the effects of TY exercise on health, physical function and quality of life in patients with TNS. A randomized clinical trial was conducted from April to July 2023 (TCTR20230920002, 10/2023). Seventy-eight volunteers with TNS participated in the study, performing TY exercises, while continuing their routine daily life (CON) for 6 weeks, with week 8 as a follow-up appointment. Clinical evaluation was conducted using a numerical pain-rating scale, functional disability scored by the neck disability index questionnaire (NDI), range of motion (ROM) and cervical vertebral angle, rounded shoulder angle by goniometry, and health-related quality of life (QoL) assessed by the 36-Item Short Form Survey. The results of the numerical pain-rating scale for TY group in the follow-up (6.71±0.52 weeks) were significantly different (p-value < 0.001) from the baseline (4.18±0.95) while the CON group showed no change. The NDI also decreased from the baseline (5.03±1.38) in the TY group, while the CON group remained at 12.03±1.98. The data of craniovertebral angle of TY group show an increase from baseline (62.44±2.32) while CON group was 39.37±4.73. The results showed that the rounded shoulder angle of TY group decreased to the normal range. The TY group shows an increased degree from baseline. The results for the TY group demonstrated a significant increase in QoL. These findings suggest that TY exercise is effective for relieving TNS when compared with the CON group. These positive outcomes provide strong support for the use of TY as an effective intervention for treating TNS symptoms.

Medial degenerative disease of the knee without radiographic osteoarthritis is a good indication for medial open wedge high tibial osteotomy.

Medial open wedge high tibial osteotomy (MOWHTO) is a well-established surgical procedure for osteoarthritis (OA) of the knee with varus malalignment. However, it is uncertain whether MOWHTO is an effective surgical procedure for early OA. This study aimed to evaluate the clinical results of MOWHTO for early OA of the knee with varus malalignment. This was a retrospective analysis of 87 patients in whom varus malalignment was corrected by MOWHTO between January 2017 and December 2022. Kellgren-Lawrence grade 0-1 was defined as early OA and grade ≥ 2 as established OA. Range of motion at the knee, Forgotten Joint Score-12, Knee Injury and Osteoarthritis Outcome Score, and radiological findings were compared between the early OA group and the established OA group. The established OA group (n = 49) was significantly older than the early OA group (n = 38) (p = 0.02). There were no differences between the groups in preoperative or postoperative hip-knee-ankle angle or range of motion or in improvements in the Forgotten Joint Score-12 or Knee Injury and Osteoarthritis Outcome Score. The median follow-up duration was more than 24.0months in both groups. MOWHTO had a good clinical outcome in patients with early OA and varus malalignment over a median follow-up of 2years. III, retrospective study.

A Hierarchical-Based Learning Approach for Multi-Action Intent Recognition.

Recent applications of wearable inertial measurement units (IMUs) for predicting human movement have often entailed estimating action-level (e.g., walking, running, jumping) and joint-level (e.g., ankle plantarflexion angle) motion. Although action-level or joint-level information is frequently the focus of movement intent prediction, contextual information is necessary for a more thorough approach to intent recognition. Therefore, a combination of action-level and joint-level information may offer a more comprehensive approach to predicting movement intent. In this study, we devised a novel hierarchical-based method combining action-level classification and subsequent joint-level regression to predict joint angles 100 ms into the future. K-nearest neighbors (KNN), bidirectional long short-term memory (BiLSTM), and temporal convolutional network (TCN) models were employed for action-level classification, and a random forest model trained on action-specific IMU data was used for joint-level prediction. A joint-level action-generic model trained on multiple actions (e.g., backward walking, kneeling down, kneeling up, running, and walking) was also used for predicting the joint angle. Compared with a hierarchical-based approach, the action-generic model had lower prediction error for backward walking, kneeling down, and kneeling up. Although the TCN and BiLSTM classifiers achieved classification accuracies of 89.87% and 89.30%, respectively, they did not surpass the performance of the action-generic random forest model when used in combination with an action-specific random forest model. This may have been because the action-generic approach was trained on more data from multiple actions. This study demonstrates the advantage of leveraging large, disparate data sources over a hierarchical-based approach for joint-level prediction. Moreover, it demonstrates the efficacy of an IMU-driven, task-agnostic model in predicting future joint angles across multiple actions.

Lower Limb Joint Angle Prediction Based on Multistream Signaling and Quantile Regression, Temporal Convolution Network–Bidirectional Long Short-Term Memory Network Neural Network

In recent years, the increasing number of patients with spinal cord injuries, strokes, and lower limb disabilities has led to the gradual development of rehabilitation-assisted exoskeleton robots. A critical aspect of these robots is their ability to accurately sense human movement intentions to achieve smooth and natural control. This paper describes research carried out on predicting the motion angles of human lower limb joints. Based on the design of a signal acquisition system for physiological muscle signals and inertial measurement unit (IMU) data, a hybrid neural network prediction model (QRTCN-BiLSTM) and a single neural network prediction model (QRBiLSTM) were constructed using quantile regression, temporal convolution network (TCN) and bidirectional long short-term memory network (BiLSTM), respectively. At the same time, 7-channel surface electromyographic signals (sEMG) and 12-channel IMU data from hip and knee joints were collected and input into the QRBiLSTM and QRTCN-BiLSTM models to unfold the training and analyze the comparison. The results show that the QRTCN-BiLSTM model can more accurately infer human movement intention and provide a more reliable and accurate prediction tool for human–robot interaction research in rehabilitation robotics.

A096: Analysis of Knee Joint Load Characteristics in Different Angle of Stride Movements in Table Tennis

Objectives: Stride is a typical type of footwork found in table tennis. During the game, athletes need to repeat stride movements at different angles according to the direction of the incoming ball, which makes the knee joint twist and flex, increases the burden on the knee joint, and increases the risk of knee injury. However, the effect of different angle stride movements on the load characteristics of athletes' knee joints is still unclear and needs further research. Therefore, this study used biomechanical research methods to explore the effects of 180° and 45° stride movements on the knee load characteristics of table tennis players. Methods: Sixteen male table tennis athletes were selected to collect kinematic and dynamic data using Qualisys 3D motion capture system and AMTI 3D force plate at a frequency of 1000Hz, and the knee joint moment, anterior shear force, knee joint contact force and ACL force were calculated by using Opensim musculoskeletal simulation system, and these indices were standardized. The independent sample t-test was used to analyze the knee joint load characteristics of athletes with different angles of stride. Result: The front shear force of the 45° step was 10.53±2.07 N/kg, the extension moment was 4.26±0.27 N·m/kg, the abduction moment was 4.52±0.78 N·m/kg, the medial compartment contact force was 12.9±3.27 N/kg, and the ACL force was 12.87±3.08 N/kg. The front shear force of the 180° step was 5.30±0.49 N/kg, the extension moment was 2.62±0.30 N·m/kg, the abduction moment was 3.52±0.32 N·m/kg, the medial compartment force was 6.35±1.67 N/kg, and the ACL force was 9.46±3.81 N/kg. The front shear force, extension moment, medial compartment contact force and ACL force of the 45° step were significantly greater than those of the 180° step (P < 0.05). Conclusion: There are significant differences in the biomechanical results between different angles strides, and the 45° stride affects the knee joint load more, and potentially produces greater tension on the ACL, resulting in an increased risk of knee joint injury, suggesting that athletes have higher requirements for lower limb strength when performing 45° strides.

A V‐Shaped In‐Pipe Robot to Travel Through Complex Winding Pathways in Three Dimensions

ABSTRACTThis paper presents a V‐shaped gas pipeline inspection robot which achieves high roll rotation performance, out‐of‐plane double elbow travel performance, and inverted siphon adaptability at high speed without requiring complicated manual operation. The principle for traveling through the out‐of‐plane double elbow was theoretically demonstrated and proven experimentally. The pitch angle of the robot's spiral motion, which is derived from the relationship between the roll angle of the spherical wheel and the angle of the V‐shaped joint, was also both theoretically and experimentally verified. Finally, field tests were conducted not only indoors but also outdoors on 8‐in steel pipes, and the robot successfully adapted to the out‐of‐plane double elbows, inverted siphons, and even buried pipes that were more than 20 years old. The robot even traveled up to 40 m without any problems, and returned safely after inspection and exploration.

The Development of a System for Elbow Joint Range of Motion Measurement Based on Image Recognition and Myoelectric Signals.

After a fracture, patients have reduced willingness to bend and extend their elbow joint due to pain, resulting in muscle atrophy, contracture, and stiffness around the elbow. Moreover, this may lead to progressive atrophy of the muscles around the elbow, resulting in permanent functional loss. Currently, a goniometer is used to measure the range of motion, ROM, to evaluate the recovery of the affected limb. However, the measurement process can cause measurement errors ranging from 4 to 5 degrees due to unskilled operation or inaccurate placement, leading to inaccurate judgments of the recovery of the affected limb. In addition, the current measurement methods do not include an assessment of muscle endurance. In this paper, the proposed device combines image recognition and a myoelectric signal sensor to measure the joint movement angle and muscle endurance. The movement angle of the elbow joint is measured using image recognition. Muscle endurance is measured using the myoelectric signal sensor. The measured data are transmitted to a cloud database via an app we have proposed to help medical staff track a patient's recovery status. The average error value of static image recognition and verification is up to 0.84 degrees. The average error value of dynamic image recognition and verification is less than 1%. The average error of total harmonic distortion (THD) verified by the myoelectric signal sensor is less than ±3%. It was proven that our system could be applied to measuring elbow joint range of motion. Since this is pilot research, most of the measurement subjects are healthy people without dysfunction in arm movement, and it is difficult to observe differences in the measurement results. In the future, experiments will be conducted on patients with elbow fractures through the IRB. This is expected to achieve the effect of encouraging patients to be actively rehabilitated at home through their measurement data and images of their actions being displayed in real time using our cheap and compact device and app.

Posterior Lumbar Element Enforcement by Decompression Alone with Interspinous Fixation without Interbody Fusion for the Surgical Management of Lumbar Spondylolisthesis.

In degenerative lumbar spondylolisthesis, interbody fusion surgery (IFS) has long been recommended as the gold standard of surgical management. However, IFS is less recommended for high-risk patients such as the elderly because it involves extensive surgery, with a long operation time and high volumes of blood loss, which lead to marked perioperative morbidity. We report an alternative primary and salvage treatment technique for high-risk lumbar spondylolisthesis through posterior lumbar element reinforcement using interspinous fixation (ISF) and decompression alone without interbody fusion. Plain radiographs, computed tomography scans, and magnetic resonance imaging, taken at different intervals, were used to measure local disc height (DH), vertebral body slippage (BS), and segmental motion angle (SMA). A visual analogue scale (VAS) and the Oswestry disability index (ODI) were applied pre-operation and at the last follow-up. The local SMA decreased significantly by 3.46±3.07°, from 10.61±3.42° preoperatively to 7.15±3.70 at the last follow-up (p<0.001). The DH decreased from 8.61±2.88 mm preoperatively to 8.41±2.48 mm at the last follow-up (p=0.074). The BS decreased from 3.49±4.29 mm preoperatively to 3.41±4.91 mm at the last follow-up (p=0.092). None of the patients reported worsening pain or an increased ODI after surgery, and there were no surgery-related complications. Posterior lumbar element reinforcement by decompression alone with SPIRE™ fixation is an alternative primary and salvage treatment option for select patients with spondylolisthesis.

Investigation research on the mechanism of knee joint injury in table tennis players landing before and after fatigue during stroke play

This study investigated the relationship between lower extremity biomechanics and anterior cruciate ligament (ACL) injury in table tennis players before and after fatigue. We compared the biomechanical changes in the lower limbs of table tennis players during landing after completing a chasse-step while stroking, both before and after fatigue. A further aim was to examine ACL injury and provide a reference for training table tennis players. Ten national Level I table tennis players underwent lower extremity neuromuscular fatigue by running at a constant speed. Biomechanical data of the athletes were collected before and after fatigue. The effects of movement and characteristic time before and after fatigue on biomechanics were determined using a paired sample t-test. After fatigue, the angle of the ankle joint and the range of motion of the knee joint were significantly reduced (p &lt; 0.001), while the angle of motion of the hip joint did not change considerably (p = 0.747). The angular velocity of the ankle and knee joints increased significantly after fatigue (p &lt; 0.001), but the angular velocity of the hip joint decreased significantly (p = 0.013). Additionally, the ankle plantar flexion moment (p = 0.003), knee flexion moment (p &lt; 0.001), and hip flexion moment (p &lt; 0.001) increased significantly after fatigue. The ankle power (p = 0.023), knee power (p = 0.009), and hip power (p &lt; 0.001) were significantly reduced throughout the landing cycle after fatigue. Fatigue in table tennis athletes reduces the sagittal plane buckling angle of the knee and ankle joints during landing. This change increases ground reaction and knee joint forces, significantly elevating the risk of knee injuries, including ACL tears. The reduced flexion angle exposes the knee to greater torque and diminishes its shock absorption capacity, heightening the risk of lower limb injuries. These findings underscore the need to address the impact of fatigue on landing mechanics in sports training and rehabilitation, emphasizing preventive measures.

A magnetic pendulum for demonstrating Mathieu-type parametric resonance

Abstract We describe a magnetic pendulum apparatus designed for studying and demonstrating Mathieu-type parametric resonance. The apparatus features a T-shaped rigid arm with a neodymium (NdFeB) magnet bob, suspended by double V-shaped thread suspensions. It is parametrically driven by an alternating uniform magnetic field produced by Helmholtz coils. The pendulum is structurally simple and easy to implement, and its parameter-driven mechanism is transparent in terms of physics. The use of electromagnetic driving allows for precise control over both the frequency and amplitude of parameter modulation, enabling quantitative studying on parametric resonance. We have observed the first and second instability region of parametric resonance. We also theoretically analyze the impact of non-uniformity in the Helmholtz coils' magnetic field on the pendulum motion, revealing that the non-uniformity can significantly alter the pendulum's nonlinearity, influencing both the magnitude and the sign of the coefficients of the nonlinear terms. However, under the parameters of our experimental setup, the nonlinearity effect is mainly manifested in large swing angle motions. For small swing angle within 5\textsuperscript{$\circ$}, the impact of magnetic field non-uniformity on parametric resonance is negligible. The experiment reported here is appropriate for undergraduates to carry out experimental research, helping them develop a more intuitive and quantitative understanding of parametric resonance.

The thrust balance model during the dragonfly hovering flight

In recent years, the micro air vehicle (MAV) oscillations caused by thrust imbalances have received more attention. This paper proposes a dual-wing thrust balance model (DTBM) that can solve the above problem by iterating the modified rotation angle formula. The core control parameter of the DTBM model is the au angle, which refers to the angle between the wing surface and the stroke plane at the mid-stroke position during the upstroke. For each degree change in the au angle, the range of variation in the dimensionless average thrust coefficient is between 0.0225-0.0268. A thrust coefficient of 0.0225 causes the dragonfly to move forward by 9.037 cm in one second, which is equivalent to 1.29 times its body length. By using DTBM, the average thrust coefficient can be reduced to below 0.001 in just a few iterations. No matter how complex the motion pattern is, the DTBM can achieve thrust balance within 0.278 s. Through our research, when selecting the deviation angle motion of real dragonflies, the dual-wing au angles exhibit a highly linear correlation with wing spacing, called linear motion. In contrast, the nonlinear variation of the au angle appears in the hindwing of the no-deviation motion and the forewing of the elliptical deviation motion. All of the nonlinear changes are referred to as nonlinear motion. Nonlinear variation of the au angle arises from larger disturbances of the lateral force during the upstroke. The stronger lateral force is closely related to the flapping trajectory. When the flapping trajectory causes the dual-wing to closely approach each other in the mid-stroke, a continuous positive pressure zone forms between the dual-wing. The collision of the leading-edge vortex and the shedding of the trailing-edge vortex is the special flow field structure in the nonlinear motion. Guided by the DTBM, future designs of MAVs will be able to better achieve thrust balance during hovering flight, requiring only the embedding of the iteration algorithm and prediction function of the DTBM in the internal chip.

Developments on friction surfaced coatings for corrosion, wear-resistant and composite

Friction surfacing is the most recent technology applied in surface engineering for developing surface materials. It is a solid-state technique employed to coat one material over another material in order to reconstruct the worn-out parts, to enhance protection from ware and corrosion, to develop mechanical features and composite materials.This is an environmentally-safe process in which a consumable rod is deformed plastically and forms a deposit of viscoelastic material over the substrate. The thickness and properties of the layer can be controlled by the rotational speed, axial downwards force, horizontal motion, time and tilt angle. Different materials have been taken in friction surfacing for deposition. The friction surfaced coating is also modified in different way according to requirement. Friction surfacing has been significantly applied to industrial applications. This paper reviews thoroughly the properties and microstructure of friction surfaced coating using different operating parameters and processes, focusing alternative technology on future research.

Efficacy and safety of the ultraslow low-dose thrombolytic regimen for mechanical prosthetic valve thrombosis: a prospective cohort study

Abstract Background Mechanical prosthetic valve thrombosis (MPVT) remains a significant and life-threatening complication. While surgery is here considered the gold standard therapy, it has a high perioperative risk in the acute setting. Preliminary evidence suggests that an ultraslow low-dose thrombolytic regimen may offer a safer and equally effective alternative compared to both conventional fast-infusion thrombolytic approaches or surgical options. Purpose We aimed at evaluating efficacy and safety of a previously described ultraslow low-dose thrombolytic regimen for treating acute MPVT in hospitalized adult patients. Methods This prospective single-center cohort study included all consecutive adult patients with acute MPVT treated with our ultraslow low-dose thrombolytic regimen. Patients with contraindication to thrombolytic therapy or left-sided MPVT with a minimum thrombus size of 0.8 cm2 or severe dyspnea with NYHA FC IV were excluded, and considered candidate to surgery. The regimen here used consisted of 25 mg rtPA infused over 25 hours. If initially failed, a repeat 6-hour infusion of 25 mg rtPA was administered up to a maximum total cumulative dose of 150 mg or until an adverse event occurred. The primary objective was the rate of complete MPVT resolution, defined as &amp;gt;75% reduction in the obstructive gradient by transthoracic echocardiography, less than 10 degrees residual constraint in opening and closing valve motion angles as quantified by fluoroscopy, and alleviation of patients’ thrombosis-associated symptoms or signs. Results From April 2018 to November 2023, 135 infusions of thrombolytic therapy were administered in 118 patients (median age: 35 years (IQR, 25-49); 59 [50%] women) (Table 1). 12 patients had more than one episode of MPVT during the study period. Obstructive prosthetic valve thrombosis occurred in 89.6% (121/135) of cases. Pulmonary valves were most frequently affected (n = 84, 62.2%), followed by tricuspid (n = 34, 25.2%), mitral (n = 10, 7.4%), and aortic (n = 7, 5.2%) valves. A complete thrombolysis success was achieved in 119/135 episodes of thrombolytic therapy (88.1%); of these, 47/119 patients (39.5%) responded after the first thrombolytic dose. The median total dose administered was 50 mg (IQR, 25-75) over a median infusion duration of 30 hours (IQR, 25-36). Four patients responded partially to the regimen, six patients were candidates for bailout surgery, and only one fatal intracranial bleeding occurred. No other thromboembolic or bleeding adverse events were observed. Conclusion This is the largest prospective evaluation on the safety and efficacy of the ultraslow low-dose thrombolytic regimen, which proved highly effective - in this prospective cohort - in achieving prosthetic valve thrombosis resolution with minimal complications. Further larger clinical trials are warranted.Table 1- baseline CharacteristicsStudy Outcomes

Lower limbs kinematic analysis during a jump landing task in soccer players with unilateral anterior cruciate ligament reconstruction

BackgroundFatigue leads to an acute decline in muscle strength, altered patterns of lower extremity muscle activation, changes in hip and knee kinematics. In terms of the effects of fatigue on knee joint kinematics during plyometric training, there is still a lack of knowledge regarding kinematic differences between athletes who passed the ACL reconstructions rehabilitation period and healthy athletes. Therefore, this study aimed to compare lower limb joint kinematic parameters between reconstructed cruciate ligament and healthy control soccer players during jump landing in a fatigued setting.MethodsLower limb kinematic parameters were recorded in 20 professional soccer players (age, 24.95 ± 2.92 years; body mass, 77.20 ± 12.88 kg; height, 1.77 ± 3.19 m) during jump landing task before and after the fatigue protocol. The control group consisted of healthy subjects and the experimental group consisted of subjects with ACL reconstruction by thigh transplantation. Kinematic data was recorded with 4 cameras to measure lower limb angles at first foot contact and maximum range of motion.ResultsThe results showed that before fatigue, there was only a significant difference between the two groups in the maximum range of motion of the non-involved hip joint (P = 0.022) and angle of the involved hip at first contact (P = 0.049). In other data on joint range of motion or initial contact angle, no significant difference was observed between the two groups (P > 0.05). After fatigue protocol, there was a significant difference in initial foot contact in non-involved (P = 0.030), and involved (P = 0.020) hip joint angles between the two groups. However, no significant difference in initial contact angle or range of motion of other joints was observed between the groups.ConclusionsThis study shows that plyometric fatigue does not contribute to numerous changes in contact angles and range of motion in lower extremity joints in healthy soccer players and those with a history of cruciate ligament repairs.

Research on the difference of stroke characteristics and stroke effect between different stroke duration of table tennis players

This study aimed to explore the differences in joint kinematic characteristics and stroke effect between fast and slow strokes of table tennis players. Thirty-four table tennis players were randomly selected as participants for this experiment. A high-speed infrared motion capture system was used to collect kinematic data of the right-side upper and lower limb joints during strokes. Simultaneously, a high-speed camera was used to measure the stroke effect. According to the duration of a stroke, the stroke data were classified into two types: fast-stroke and slow-stroke using a two-step clustering algorithm. The duration of the three phases of fast-stroke was shorter, with faster ball speed and stronger spin. Compared with slow-stroke, fast-stroke exhibited shorter displacements in the three lower limb joints and faster linear velocities in the three upper limb joints. In addition, the motion angles of the knee and ankle joints were smaller, while the angles of the hip, shoulder, and elbow joints were larger, with higher angular velocities. Increasing the extension speed of the lower limbs, the flexion speed of the elbow joints, and the wrist movement speed can achieve fast strokes, enhancing ball speed and spin. Small and quick hip joint movement can effectively transfer energy to the upper limbs, increasing the movement speed of the elbow and wrist joints, thus improving the ball speed and spin of the stroke.

How does the position of the pelvis and femur influence the selection of prosthesis size during 2D preoperative planning for total hip arthroplasty?

PurposeTotal Hip Arthroplasty (THA) is the primary treatment for hip diseases today. Nevertheless, total hip arthroplasty has its challenges, and one of these challenges is the potential for incorrect execution of the preoperative planning process. Such errors can lead to complications such as loosening and instability of the prosthesis and leg length discrepancy. In this study, we used human phantoms to investigate the influence of pelvic and femoral factors on prosthesis size selection in the preoperative planning of total hip arthroplasty and to provide a reference standard for clinical imaging in preoperative planning of total hip arthroplasty.MethodsIn this experiment, we utilised a custom-made experimental device that enabled us to manipulate the movement of the pelvis and femur in various directions. The device also incorporated sensors to control the angle of movement. By obtaining X-rays from different positions and angles, we were able to determine the size of the prosthesis based on the 2D preoperative planning generated by the mediCAD software.ResultsWhen the pelvis was in a nonneutral position, the size of the acetabular cup varied within a range of three sizes. Similarly, when the femur was in a nonneutral position, the size of the femoral stem varied within a range of two sizes. The movement of the pelvis and femur in the coronal plane, relative to the neutral position, did not impact the selection of the prosthesis size. However, the motion of the pelvis and femur in the sagittal and transverse planes had a notable effect.ConclusionThe selection of the prosthesis size for preoperative planning can be significantly influenced by specific positions of the pelvis and femur. It is crucial for the radiographer to ensure that the pelvis and femur maintain a standard neutral position, particularly in the sagittal and transverse planes, during the image acquisition process.

Optimization Study of Coal Gangue Detection in Intelligent Coal Selection Systems Based on the Improved Yolov8n Model

To address the low recognition accuracy of models for coal gangue images in intelligent coal preparation systems—especially in identifying small target coal gangue due to factors such as camera angle changes, low illumination, and motion blur—we propose an improved coal gangue separation model, Yolov8n-improvedGD(GD—Gangue Detection), based on Yolov8n. The optimization strategy includes integrating the GCBlock(Global Context Block) from GCNet(Global Context Network) into the backbone network to enhance the model’s ability to capture long-range dependencies in images and improve recognition performance. The CGFPN (Contextual Guidance Feature Pyramid Network) module is designed to optimize the feature fusion strategy and enhance the model’s feature expression capabilities. The GSConv-SlimNeck architecture is employed to optimize computational efficiency and enhance feature map fusion capabilities, thereby improving the model’s robustness. A 160 × 160 scale detection head is incorporated to enhance the sensitivity and accuracy of small coal and gangue detection, mitigate the effects of low-quality data, and improve target localization accuracy.

An adaptive EKF‐SLAM algorithm for cooperative navigation of multi‐aircrafts

AbstractAiming at cooperative navigation of multi‐aircrafts, an adaptive EKF‐SLAM algorithm for non‐fixed landmark is proposed. First, the aircraft motion model and angle measurement model are established. Second, the fixed landmark cooperative EKF‐SLAM algorithm is established. Furthermore, a distributed EKF‐SLAM algorithm is designed. Then, the adaptive EKF‐SLAM algorithm with non‐fixed landmark is proposed. Finally, simulation results verify the effectiveness of the proposed algorithm.