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Search Results (2,545)

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Keywords = rotational motion

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10 pages, 615 KiB  
Article
Translating SGRT from Breast to Lung Cancer: A Study on Frameless Immobilization and Real-Time Monitoring Efficacy, Focusing on Setup Accuracy
by Jang Bo Shim, Hakyoung Kim, Sun Myung Kim and Dae Sik Yang
Life 2025, 15(8), 1234; https://doi.org/10.3390/life15081234 - 4 Aug 2025
Abstract
Objectives: Surface-Guided Radiation Therapy (SGRT) has been widely adopted in breast cancer radiotherapy, particularly for improving setup accuracy and motion management. Recently, its application in lung cancer has attracted growing interest due to similar needs for precision. This study investigates the feasibility and [...] Read more.
Objectives: Surface-Guided Radiation Therapy (SGRT) has been widely adopted in breast cancer radiotherapy, particularly for improving setup accuracy and motion management. Recently, its application in lung cancer has attracted growing interest due to similar needs for precision. This study investigates the feasibility and clinical utility of SGRT in lung cancer treatment, focusing on its effectiveness in patient setup and real-time motion monitoring under frameless immobilization conditions. Materials and Methods: A total of 204 treatment records from 17 patients with primary lung cancer who underwent radiotherapy at Korea University Guro Hospital between October 2024 and April 2025 were retrospectively analyzed. Patients were initially positioned using the Identify system (Varian) in the CT suite, with surface data transferred to the treatment room system. Alignment was performed to within ±1 cm and ±2° across six degrees of freedom. Cone-beam CT (CBCT) was acquired prior to treatment for verification, and treatment commenced when the Distance to Correspondence Surface (DCS) was ≤0.90. Setup deviations from the Identify system were recorded and compared with CBCT in three translational axes to evaluate positioning accuracy and PTV displacement. Results and Conclusions: The Identify system was shown to provide high setup accuracy and reliable real-time motion monitoring in lung cancer radiotherapy. Its ability to detect patient movement and automatically interrupt beam delivery contributes to enhanced treatment safety and precision. In addition, even though the maximum longitudinal (Lng) shift reached up to −1.83 cm with surface-guided setup, and up to 1.78 cm (Lat) 5.26 cm (Lng), 9.16 cm (Vrt) with CBCT-based verification, the use of Identify’s auto-interruption mode (±1 cm in translational axes, ±2° in rotational axes) allowed treatment delivery with PTV motion constrained within ±0.02 cm. These results suggest that, due to significant motion in the longitudinal direction, appropriate PTV margins should be considered during treatment planning. The Identify system enhances setup accuracy in lung cancer patients using a surface-guided approach and enables real-time tracking of intra-fractional errors. SGRT, when implemented with systems such as Identify, shows promise as a feasible alternative or complement to conventional IGRT in selected lung cancer cases. Further studies with larger patient cohorts and diverse clinical settings are warranted to validate these findings. Full article
(This article belongs to the Special Issue Current Advances in Lung Cancer Diagnosis and Treatment)
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13 pages, 1060 KiB  
Article
Condition Changes Before and After the Coronavirus Disease 2019 Pandemic in Adolescent Athletes and Development of a Non-Contact Medical Checkup Application
by Hiroaki Kijima, Toyohito Segawa, Kimio Saito, Hiroaki Tsukamoto, Ryota Kimura, Kana Sasaki, Shohei Murata, Kenta Tominaga, Yo Morishita, Yasuhito Asaka, Hidetomo Saito and Naohisa Miyakoshi
Sports 2025, 13(8), 256; https://doi.org/10.3390/sports13080256 - 4 Aug 2025
Abstract
During the coronavirus 2019 pandemic, sports activities were restricted, raising concerns about their impact on the physical condition of adolescent athletes, which remained largely unquantified. This study was designed with two primary objectives: first, to precisely quantify and elucidate the differences in the [...] Read more.
During the coronavirus 2019 pandemic, sports activities were restricted, raising concerns about their impact on the physical condition of adolescent athletes, which remained largely unquantified. This study was designed with two primary objectives: first, to precisely quantify and elucidate the differences in the physical condition of adolescent athletes before and after activity restrictions due to the pandemic; and second, to innovatively develop and validate a non-contact medical checkup application. Medical checks were conducted on 563 athletes designated for sports enhancement. Participants were junior high school students aged 13 to 15, and the sample consisted of 315 boys and 248 girls. Furthermore, we developed a smartphone application and compared self-checks using the application with in-person checks by orthopedic surgeons to determine the challenges associated with self-checks. Statistical tests were conducted to determine whether there were statistically significant differences in range of motion and flexibility parameters before and after the pandemic. Additionally, items with discrepancies between values self-entered by athletes using the smartphone application and values measured by specialists were detected, and application updates were performed. Student’s t-test was used for continuous variables, whereas the chi-square test was used for other variables. Following the coronavirus 2019 pandemic, athletes were stiffer than during the pre-pandemic period in terms of hip and shoulder joint rotation range of motion and heel–buttock distance. The dominant hip external rotation decreased from 53.8° to 46.8° (p = 0.0062); the non-dominant hip external rotation decreased from 53.5° to 48.0° (p = 0.0252); the dominant shoulder internal rotation decreased from 62.5° to 54.7° (p = 0.0042); external rotation decreased from 97.6° to 93.5° (p = 0.0282), and the heel–buttock distance increased from 4.0 cm to 10.4 cm (p < 0.0001). The heel–buttock distance and straight leg raising angle measurements differed between the self-check and face-to-face check. Although there are items that cannot be accurately evaluated by self-check, physical condition can be improved with less contact by first conducting a face-to-face evaluation under appropriate guidance and then conducting a self-check. These findings successfully address our primary objectives. Specifically, we demonstrated a significant decline in the physical condition of adolescent athletes following pandemic-related activity restrictions, thereby quantifying their impact. Furthermore, our developed non-contact medical checkup application proved to be a viable tool for monitoring physical condition with reduced contact, although careful consideration of measurable parameters is crucial. This study provides critical insights into the long-term effects of activity restrictions on young athletes and offers a practical solution for health monitoring during infectious disease outbreaks, highlighting the potential for hybrid checkup approaches. Full article
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20 pages, 4949 KiB  
Article
Motion Coupling at the Cervical Vertebral Joints in the Horse—An Ex Vivo Study Using Bone-Anchored Markers
by Katharina Bosch, Rebeka R. Zsoldos, Astrid Hartig and Theresia Licka
Animals 2025, 15(15), 2259; https://doi.org/10.3390/ani15152259 - 1 Aug 2025
Viewed by 167
Abstract
The influence of soft tissue structures, including ligaments spanning one or more intervertebral junctions and the nuchal ligament, on motion of the equine cervical joints remains unclear. The present study addressed this using four post-mortem horse specimens extending from head to withers with [...] Read more.
The influence of soft tissue structures, including ligaments spanning one or more intervertebral junctions and the nuchal ligament, on motion of the equine cervical joints remains unclear. The present study addressed this using four post-mortem horse specimens extending from head to withers with all ligaments intact. Three-dimensional kinematics was obtained from markers on the head and bone-anchored markers on each cervical and the first thoracic vertebra during rotation, lateral bending, flexion and extension of the whole head, and neck segment. Yaw, pitch, and roll angles in 8 cervical joints (total 32) were calculated. Flexion and extension were expressed mainly as pitch in 27 and 22 joints, respectively. Rotation appeared as predominantly roll in 13 joints, whereas lateral bending was represented as predominantly yaw in 1 and as roll or pitch in all other joints. Significant correlations between yaw, pitch, and roll were observed at individual cervical joints in 97% of all measurements, with the atlanto-occipital joint showing complete (100%) correlation. Most non-significant correlations occurred at the C5–C6 joint, while C6–C7 exhibited significantly lower correlation coefficients compared to other levels. The overall movement of the head and neck is not replicated at individual cervical joint levels and should be considered when evaluating equine necks in vivo. Full article
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21 pages, 8015 KiB  
Article
Differential Mechanism of 3D Motions of Falling Debris in Tunnels Under Extreme Wind Environments Induced by a Single Train and by Trains Crossing
by Wei-Chao Yang, Hong He, Yi-Kang Liu and Lun Zhao
Appl. Sci. 2025, 15(15), 8523; https://doi.org/10.3390/app15158523 (registering DOI) - 31 Jul 2025
Viewed by 99
Abstract
The extended operation of high-speed railways has led to an increased incidence of tunnel lining defects, with falling debris posing a significant safety threat. Within tunnels, single-train passage and trains-crossing events constitute the most frequent operational scenarios, both generating extreme aerodynamic environments that [...] Read more.
The extended operation of high-speed railways has led to an increased incidence of tunnel lining defects, with falling debris posing a significant safety threat. Within tunnels, single-train passage and trains-crossing events constitute the most frequent operational scenarios, both generating extreme aerodynamic environments that alter debris trajectories from free fall. To systematically investigate the aerodynamic differences and underlying mechanisms governing falling debris behavior under these two distinct conditions, a three-dimensional computational fluid dynamics (CFD) model (debris–air–tunnel–train) was developed using an improved delayed detached eddy simulation (IDDES) turbulence model. Comparative analyses focused on the translational and rotational motions as well as the aerodynamic load coefficients of the debris in both single-train and trains-crossing scenarios. The mechanisms driving the changes in debris aerodynamic behavior are elucidated. Findings reveal that under single-train operation, falling debris travels a greater distance compared with trains-crossing conditions. Specifically, at train speeds ranging from 250–350 km/h, the average flight distances of falling debris in the X and Z directions under single-train conditions surpass those under trains crossing conditions by 10.3 and 5.5 times, respectively. At a train speed of 300 km/h, the impulse of CFx and CFz under single-train conditions is 8.6 and 4.5 times greater than under trains-crossing conditions, consequently leading to the observed reduction in flight distance. Under the conditions of trains crossing, the falling debris is situated between the two trains, and although the wind speed is low, the flow field exhibits instability. This is the primary factor contributing to the reduced flight distance of the falling debris. However, it also leads to more pronounced trajectory deviations and increased speed fluctuations under intersection conditions. The relative velocity (CRV) on the falling debris surface is diminished, resulting in smaller-scale vortex structures that are more numerous. Consequently, the aerodynamic load coefficient is reduced, while the fluctuation range experiences an increase. Full article
(This article belongs to the Special Issue Transportation and Infrastructures Under Extreme Weather Conditions)
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14 pages, 1980 KiB  
Review
Ultrasound in Adhesive Capsulitis: A Narrative Exploration from Static Imaging to Contrast-Enhanced, Dynamic and Sonoelastographic Insights
by Wei-Ting Wu, Ke-Vin Chang, Kamal Mezian, Vincenzo Ricci, Consuelo B. Gonzalez-Suarez and Levent Özçakar
Diagnostics 2025, 15(15), 1924; https://doi.org/10.3390/diagnostics15151924 - 31 Jul 2025
Viewed by 221
Abstract
Adhesive capsulitis is a painful and progressive condition marked by significant limitations in shoulder mobility, particularly affecting external rotation. Although magnetic resonance imaging is regarded as the reference standard for assessing intra-articular structures, its high cost and limited availability present challenges in routine [...] Read more.
Adhesive capsulitis is a painful and progressive condition marked by significant limitations in shoulder mobility, particularly affecting external rotation. Although magnetic resonance imaging is regarded as the reference standard for assessing intra-articular structures, its high cost and limited availability present challenges in routine clinical use. In contrast, musculoskeletal ultrasound has emerged as an accessible, real-time, and cost-effective imaging modality for both the diagnosis and treatment guidance of adhesive capsulitis. This narrative review compiles and illustrates current evidence regarding the role of ultrasound, encompassing static B-mode imaging, dynamic motion analysis, contrast-enhanced techniques, and sonoelastography. Key sonographic features—such as thickening of the coracohumeral ligament, fibrosis in the axillary recess, and abnormal tendon kinematics—have been consistently associated with adhesive capsulitis and demonstrate favorable diagnostic performance. Advanced methods like contrast-enhanced ultrasound and elastography provide additional functional insights (enabling evaluation of capsular stiffness and vascular changes) which may aid in disease staging and prediction of treatment response. Despite these advantages, the clinical utility of ultrasound remains subject to operator expertise and technical variability. Limited visualization of intra-articular structures and the absence of standardized scanning protocols continue to pose challenges. Nevertheless, ongoing advances in its technology and utility standardization hold promise for the broader application of ultrasound in clinical practice. With continued research and validation, ultrasound is positioned to play an increasingly central role in the comprehensive assessment and management of adhesive capsulitis. Full article
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13 pages, 2066 KiB  
Article
Sport-Specific Shoulder Rotator Adaptations: Strength, Range of Motion, and Asymmetries in Female Volleyball and Handball Athletes
by Manca Lenart, Žiga Kozinc and Urška Čeklić
Symmetry 2025, 17(8), 1211; https://doi.org/10.3390/sym17081211 - 30 Jul 2025
Viewed by 198
Abstract
This study aimed to compare isometric strength, range of motion (RoM), and strength ratios of shoulder internal and external rotators between female volleyball and hand ball players Twenty-five volleyball players (age = 21.8 ± 4.8 years, height = 178.5 ± 7.1 cm, mass [...] Read more.
This study aimed to compare isometric strength, range of motion (RoM), and strength ratios of shoulder internal and external rotators between female volleyball and hand ball players Twenty-five volleyball players (age = 21.8 ± 4.8 years, height = 178.5 ± 7.1 cm, mass = 69.3 ± 7.7 kg) and twenty-four handball players (age = 19.5 ± 2.9 years, height = 169.7 ± 6.4 cm, mass = 67.6 ± 8.4 kg), all competing in the Slovenian 1st national league, participated. Maximal isometric strength and passive RoM of internal and external rotation were measured bilaterally using a handheld dynamometer and goniometer, respectively. A significant group × side interaction was observed for internal rotation RoM (F = 5.41; p = 0.024; η2 = 0.10), with volleyball players showing lower RoM on the dominant side (p = 0.001; d = 0.89), but this was not the case for handball players (p = 0.304). External rotation strength also showed a significant interaction (F = 9.34; p = 0.004; η2 = 0.17); volleyball players were stronger in the non-dominant arm (p = 0.033), while handball players were stronger in the dominant arm (p = 0.041). The external-to-internal rotation strength ratio was significantly lower on the dominant side in volleyball players compared to handball players (p = 0.047; d = 0.59). Findings suggest sport-specific adaptations and asymmetries in shoulder function, emphasizing the need for sport-specific and individually tailored injury prevention strategies. Volleyball players, in particular, may benefit from targeted strengthening of external rotators and flexibility training to address imbalances. Full article
(This article belongs to the Special Issue Application of Symmetry in Biomechanics)
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18 pages, 4452 KiB  
Article
Upper Limb Joint Angle Estimation Using a Reduced Number of IMU Sensors and Recurrent Neural Networks
by Kevin Niño-Tejada, Laura Saldaña-Aristizábal, Jhonathan L. Rivas-Caicedo and Juan F. Patarroyo-Montenegro
Electronics 2025, 14(15), 3039; https://doi.org/10.3390/electronics14153039 - 30 Jul 2025
Viewed by 264
Abstract
Accurate estimation of upper-limb joint angles is essential in biomechanics, rehabilitation, and wearable robotics. While inertial measurement units (IMUs) offer portability and flexibility, systems requiring multiple inertial sensors can be intrusive and complex to deploy. In contrast, optical motion capture (MoCap) systems provide [...] Read more.
Accurate estimation of upper-limb joint angles is essential in biomechanics, rehabilitation, and wearable robotics. While inertial measurement units (IMUs) offer portability and flexibility, systems requiring multiple inertial sensors can be intrusive and complex to deploy. In contrast, optical motion capture (MoCap) systems provide precise tracking but are constrained to controlled laboratory environments. This study presents a deep learning-based approach for estimating shoulder and elbow joint angles using only three IMU sensors positioned on the chest and both wrists, validated against reference angles obtained from a MoCap system. The input data includes Euler angles, accelerometer, and gyroscope data, synchronized and segmented into sliding windows. Two recurrent neural network architectures, Convolutional Neural Network with Long-short Term Memory (CNN-LSTM) and Bidirectional LSTM (BLSTM), were trained and evaluated using identical conditions. The CNN component enabled the LSTM to extract spatial features that enhance sequential pattern learning, improving angle reconstruction. Both models achieved accurate estimation performance: CNN-LSTM yielded lower Mean Absolute Error (MAE) in smooth trajectories, while BLSTM provided smoother predictions but underestimated some peak movements, especially in the primary axes of rotation. These findings support the development of scalable, deep learning-based wearable systems and contribute to future applications in clinical assessment, sports performance analysis, and human motion research. Full article
(This article belongs to the Special Issue Wearable Sensors for Human Position, Attitude and Motion Tracking)
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16 pages, 1571 KiB  
Article
Effectiveness of Ultrasound-Guided Lavage for Rotator Cuff Calcific Tendinopathy: A Case Series Study from a Clinical and Radiological Perspective
by Lucrezia Moggio, Michele Mercurio, Nicola Marotta, Umile Giuseppe Longo, Giorgio Gasparini, Antonio Ammendolia and Alessandro de Sire
J. Clin. Med. 2025, 14(15), 5376; https://doi.org/10.3390/jcm14155376 - 30 Jul 2025
Viewed by 252
Abstract
Background/Objectives: Rotator cuff calcific tendinopathy (RCCT) is one of the most common causes of non-traumatic shoulder pain. To date, there is still no consensus regarding the most effective method for its treatment. Ultrasound-guided percutaneous aspiration is suggested during the reabsorption phase of [...] Read more.
Background/Objectives: Rotator cuff calcific tendinopathy (RCCT) is one of the most common causes of non-traumatic shoulder pain. To date, there is still no consensus regarding the most effective method for its treatment. Ultrasound-guided percutaneous aspiration is suggested during the reabsorption phase of calcific metaplasia. We aimed to evaluate the effectiveness of ultrasound-guided lavage for RCCT from a clinical and radiological perspective. Methods: We involved patients affected by RCCT of the supraspinatus tendon. The approach used for the calcification lavage was the one-needle technique, consisting in inserting a 16–18 G needle on a 20 mL syringe with 0.9% saline solution, in the calcific metaplasia, under ultrasound guidance, using an in-plane approach; the repetitive action of pressing and releasing the plunger was repeated until the contents of the syringe became milky, at which point the syringe was replaced with a new one, always containing saline solution. The physiotherapy treatment began 7 days after the procedure. We assessed the Numeric Rating Scale, the Gartner classification, the Disability of the Arm, Shoulder and Hand scale, the Constant–Murley shoulder score, and the passive range of motion of flexion and abduction. Results: We included 23 subjects. The analysis of the data at baseline and t1 showed a statistically significant improvement in all the functional variables (p < 0.05). This result was mainly evident for pain, with a p-value of 0.001. Conclusions: The findings of the present prospective case series study showed an improvement in the clinical and radiological outcomes after ultrasound-guided percutaneous aspiration for rotator cuff calcific tendinopathy. Full article
(This article belongs to the Special Issue Musculoskeletal Imaging and Intervention)
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25 pages, 6401 KiB  
Article
Efficient Sampling Schemes for 3D Imaging of Radar Target Scattering Based on Synchronized Linear Scanning and Rotational Motion
by Changyu Lou, Jingcheng Zhao, Xingli Wu, Yuchen Zhang, Zongkai Yang, Jiahui Li and Jungang Miao
Remote Sens. 2025, 17(15), 2636; https://doi.org/10.3390/rs17152636 - 29 Jul 2025
Viewed by 246
Abstract
Three-dimensional (3D) radar imaging is essential for target detection and measurement of scattering characteristics. Cylindrical scanning, a prevalent spatial sampling technique, provides benefits in engineering applications and has been extensively utilized for assessing the radar stealth capabilities of large aircraft. Traditional cylindrical scanning [...] Read more.
Three-dimensional (3D) radar imaging is essential for target detection and measurement of scattering characteristics. Cylindrical scanning, a prevalent spatial sampling technique, provides benefits in engineering applications and has been extensively utilized for assessing the radar stealth capabilities of large aircraft. Traditional cylindrical scanning generally utilizes highly sampled full-coverage techniques, leading to an excessive quantity of sampling points and diminished image efficiency, constraining its use for quick detection applications. This work presents an efficient 3D sampling strategy that integrates vertical linear scanning with horizontal rotating motion to overcome these restrictions. A joint angle–space sampling model is developed, and geometric constraints are implemented to enhance the scanning trajectory. The experimental results demonstrate that, compared to conventional techniques, the proposed method achieves a 94% reduction in the scanning duration while maintaining a peak sidelobe level ratio (PSLR) of 12 dB. Furthermore, this study demonstrates that 3D imaging may be accomplished solely by a “V”-shaped trajectory, efficiently determining the minimal possible sampling aperture. This approach offers novel insights and theoretical backing for the advancement of high-efficiency, low-redundancy 3D radar imaging systems. Full article
(This article belongs to the Special Issue Recent Advances in SAR: Signal Processing and Target Recognition)
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18 pages, 1154 KiB  
Article
Effectiveness and Safety of Portable Ultrasound-Guided Pharmacopuncture for Cervical Myofascial Pain Syndrome: A Prospective Observational Multi-Center Study
by Robin Kwon, Kwangho Kim, Young-Ung Lee, Sanghyuk Kwon, Juhwan Song, Seongjun Park, Junhui Kwon, Hyeon Joon Hong, Youngyun Lee, Jungtae Leem, Hongmin Chu and Cheol-Hyun Kim
Medicina 2025, 61(8), 1371; https://doi.org/10.3390/medicina61081371 - 29 Jul 2025
Viewed by 370
Abstract
Background and Objectives: This study aimed to evaluate the clinical effectiveness and safety of ultrasound-guided pharmacopuncture (UGP) in comparison to non-guided pharmacopuncture (NGP) for the treatment of acute cervical myofascial pain syndrome (C-MPS) in primary care settings. Materials and Methods: This [...] Read more.
Background and Objectives: This study aimed to evaluate the clinical effectiveness and safety of ultrasound-guided pharmacopuncture (UGP) in comparison to non-guided pharmacopuncture (NGP) for the treatment of acute cervical myofascial pain syndrome (C-MPS) in primary care settings. Materials and Methods: This multi-center, prospective observational study included 97 patients diagnosed with acute C-MPS. Participants received a single session of either UGP or NGP at one of seven primary care institutions. Pain intensity was measured using the Numerical Rating Scale (NRS), and cervical function was assessed through active Range of Motion (ROM) tests conducted before and after treatment. We conducted follow-up interviews within 48 h after treatment to monitor adverse events. Results: Both groups showed significant improvements in pain levels and cervical ROM after treatment. The UGP group showed a greater reduction in NRS scores compared to the NGP group (p < 0.001). Notable enhancements in cervical extension and rotation on the affected side were also observed in the UGP group (p < 0.01), whereas changes in flexion and lateral flexion were similar between the two groups. No serious adverse events were reported. Conclusions: UGP has shown superior pain reduction and a greater improvement in specific cervical motions compared to non-guided treatments, indicating enhanced precision and therapeutic efficacy. Furthermore, no serious adverse events were reported, suggesting that UGP is a safe and effective non-surgical intervention for acute C-MPS in real-world primary care settings. Full article
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33 pages, 4686 KiB  
Article
Modeling of Dynamics of Nonideal Mixer at Oscillation and Aperiodic Damped Mode of Driving Member Motion
by Kuatbay Bissembayev, Zharilkassin Iskakov, Assylbek Jomartov and Akmaral Kalybayeva
Appl. Sci. 2025, 15(15), 8391; https://doi.org/10.3390/app15158391 - 29 Jul 2025
Viewed by 242
Abstract
The dynamics of the vibrational mode of motion of the driving member of a nonideal system, a mixing–whipping device based on a simple slide-crank mechanism, was studied. The highly nonlinear differential equations of motion were solved numerically by the Runge–Kutta method. The interaction [...] Read more.
The dynamics of the vibrational mode of motion of the driving member of a nonideal system, a mixing–whipping device based on a simple slide-crank mechanism, was studied. The highly nonlinear differential equations of motion were solved numerically by the Runge–Kutta method. The interaction of the mixing–whipping device with the nonideal excitation source causes the rotational speed of the engine shaft and the rotation angle of the driving member to fluctuate, accomplishing a damped process. The parameters of the device and the nonideal energy source have an effect on the kinematic, vibrational and energy characteristics of the system. An increase in the engine’s torque, crank length, number and radius of piston holes, and piston mass, as well as a decrease in the fluid’s density, leads to a reduction in the oscillation range of the crank angle, amplitude and period of angular velocity oscillations of the engine shaft and the mixing–whipping force power. The effects of a nonideal energy source may be used in designing a mixing–whipping device based on a slider-crank mechanism to select effective system parameters and an energy-saving motor in accordance with the requirements of technological processes and products. Full article
(This article belongs to the Special Issue Dynamics and Vibrations of Nonlinear Systems with Applications)
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20 pages, 3364 KiB  
Article
Inverse Kinematics of a Serial Manipulator with a Free Joint for Aerial Manipulation
by Alberto Pasetto, Mattia Pedrocco, Riccardo Zenari and Silvio Cocuzza
Appl. Sci. 2025, 15(15), 8390; https://doi.org/10.3390/app15158390 - 29 Jul 2025
Viewed by 139
Abstract
In Aerial Manipulation, the motion of the robotic arm can cause unwanted movements of the flying base affecting the trajectory tracking capability. A possible solution to reduce these disturbances is to use a free revolute joint between the flying base and the manipulator, [...] Read more.
In Aerial Manipulation, the motion of the robotic arm can cause unwanted movements of the flying base affecting the trajectory tracking capability. A possible solution to reduce these disturbances is to use a free revolute joint between the flying base and the manipulator, thus reducing the torque applied to the base from the manipulator. In this paper, a novel approach to solve the inverse kinematics of an aerial manipulator with a free revolute joint is presented. The approach exploits the Generalized Jacobian to deal with the presence of a mobile base, and the dynamics of the system is considered to predict the motion of the non-actuated joint; external forces acting on the system are also included. The method is implemented in MATLAB for a planar case considering the parameters of a real manipulator attached to a real octocopter. The tracking of a trajectory with the end-effector and a load picking task are simulated for a non-redundant and for a redundant manipulator. Simulation results demonstrate the capability of this approach in following the desired trajectories and reducing rotation and horizontal translation of the base. Full article
(This article belongs to the Section Robotics and Automation)
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32 pages, 18111 KiB  
Article
Across-Beam Signal Integration Approach with Ubiquitous Digital Array Radar for High-Speed Target Detection
by Le Wang, Haihong Tao, Aodi Yang, Fusen Yang, Xiaoyu Xu, Huihui Ma and Jia Su
Remote Sens. 2025, 17(15), 2597; https://doi.org/10.3390/rs17152597 - 25 Jul 2025
Viewed by 194
Abstract
Ubiquitous digital array radar (UDAR) extends the integration time of moving targets by deploying a wide transmitting beam and multiple narrow receiving beams to cover the entire observed airspace. By exchanging time for energy, it effectively improves the detection ability for weak targets. [...] Read more.
Ubiquitous digital array radar (UDAR) extends the integration time of moving targets by deploying a wide transmitting beam and multiple narrow receiving beams to cover the entire observed airspace. By exchanging time for energy, it effectively improves the detection ability for weak targets. Nevertheless, target motion introduces severe across-range unit (ARU), across-Doppler unit (ADU), and across-beam unit (ABU) effects, dispersing target energy across the range–Doppler-beam space. This paper proposes a beam domain angle rotation compensation and keystone-matched filtering (BARC-KTMF) algorithm to address the “three-crossing” challenge. This algorithm first corrects ABU by rotating beam–domain coordinates to align scattered energy into the final beam unit, reshaping the signal distribution pattern. Then, the KTMF method is utilized to focus target energy in the time-frequency domain. Furthermore, a special spatial windowing technique is developed to improve computational efficiency through parallel block processing. Simulation results show that the proposed approach achieves an excellent signal-to-noise ratio (SNR) gain over the typical single-beam and multi-beam long-time coherent integration (LTCI) methods under low SNR conditions. Additionally, the presented algorithm also has the capability of coarse estimation for the target incident angle. This work extends the LTCI technique to the beam domain, offering a robust framework for high-speed weak target detection. Full article
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26 pages, 8292 KiB  
Review
Progress in the Circular Arc Source Structure and Magnetic Field Arc Control Technology for Arc Ion Plating
by Hao Du, Ke Zhang, Debin Liu and Wenchang Lang
Materials 2025, 18(15), 3498; https://doi.org/10.3390/ma18153498 - 25 Jul 2025
Viewed by 170
Abstract
Aiming at the goal of preparing high-quality coatings, this paper reviews the progress on circular arc source structure and magnetic field arc controlling technology in arc ion plating (AIP), with a focus on design characteristics of the different structures and configuration optimization of [...] Read more.
Aiming at the goal of preparing high-quality coatings, this paper reviews the progress on circular arc source structure and magnetic field arc controlling technology in arc ion plating (AIP), with a focus on design characteristics of the different structures and configuration optimization of the corresponding magnetic fields. The circular arc source, due to its simple structure, convenient installation, flexible target combination, high cooling efficiency, and high ionization rate and deposition rate, has shown significant application potential in AIP technology. In terms of magnetic field arc controlling technology, this paper delves into the design progress of various magnetic field configurations, including fixed magnetic fields generated by permanent magnets, dynamic rotating magnetic fields, axially symmetric magnetic fields, rotating transverse magnetic fields, and multi-mode alternating electromagnetic coupling fields. By designing the magnetic field distribution reasonably, the trajectory and velocity of the arc spot can be controlled precisely, thus reducing the generation of macroparticles, improving target utilization, and enhancing coating uniformity. In particular, the introduction of multi-mode magnetic field coupling technology has broken through the limitations of traditional single magnetic field structures, achieving comprehensive optimization of arc spot motion and plasma transport. Hopefully, these research advances provide an important theoretical basis and technical support for the application of AIP technology in the preparation for high-quality decorative and functional coatings. Full article
(This article belongs to the Section Materials Physics)
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22 pages, 6823 KiB  
Article
Design Optimization of Valve Assemblies in Downhole Rod Pumps to Enhance Operational Reliability in Oil Production
by Seitzhan Zaurbekov, Kadyrzhan Zaurbekov, Doszhan Balgayev, Galina Boiko, Ertis Aksholakov, Roman V. Klyuev and Nikita V. Martyushev
Energies 2025, 18(15), 3976; https://doi.org/10.3390/en18153976 - 25 Jul 2025
Viewed by 273
Abstract
This study focuses on the optimization of valve assemblies in downhole rod pumping units (DRPUs), which remain the predominant artificial lift technology in oil production worldwide. The research addresses the critical issue of premature failures in DRPUs caused by leakage in valve pairs, [...] Read more.
This study focuses on the optimization of valve assemblies in downhole rod pumping units (DRPUs), which remain the predominant artificial lift technology in oil production worldwide. The research addresses the critical issue of premature failures in DRPUs caused by leakage in valve pairs, i.e., a problem that accounts for approximately 15% of all failures, as identified in a statistical analysis of the 2022 operational data from the Uzen oilfield in Kazakhstan. The leakage is primarily attributed to the accumulation of mechanical impurities and paraffin deposits between the valve ball and seat, leading to concentrated surface wear and compromised sealing. To mitigate this issue, a novel valve assembly design was developed featuring a flow turbulizer positioned beneath the valve seat. The turbulizer generates controlled vortex motion in the fluid flow, which increases the rotational frequency of the valve ball during operation. This motion promotes more uniform wear across the contact surfaces and reduces the risk of localized degradation. The turbulizers were manufactured using additive FDM technology, and several design variants were tested in a full-scale laboratory setup simulating downhole conditions. Experimental results revealed that the most effective configuration was a spiral plate turbulizer with a 7.5 mm width, installed without axis deviation from the vertical, which achieved the highest ball rotation frequency and enhanced lapping effect between the ball and the seat. Subsequent field trials using valves with duralumin-based turbulizers demonstrated increased operational lifespans compared to standard valves, confirming the viability of the proposed solution. However, cases of abrasive wear were observed under conditions of high mechanical impurity concentration, indicating the need for more durable materials. To address this, the study recommends transitioning to 316 L stainless steel for turbulizer fabrication due to its superior tensile strength, corrosion resistance, and wear resistance. Implementing this design improvement can significantly reduce maintenance intervals, improve pump reliability, and lower operating costs in mature oilfields with high water cut and solid content. The findings of this research contribute to the broader efforts in petroleum engineering to enhance the longevity and performance of artificial lift systems through targeted mechanical design improvements and material innovation. Full article
(This article belongs to the Special Issue Petroleum and Natural Gas Engineering)
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