High-speed Motion Research Articles

High speed underwater hydrogel robots with programmable motions powered by light

Stimuli-responsive shape-changing hydrogels are attractive candidates for use as underwater soft robots. The bottleneck lies in the low actuation speed inherently limited by the water diffusion between hydrogels and their surrounding environment. In addition, accessing complex motions is restricted by the material fabrication methods. Here we report a hitherto unknown mechanism to achieve high-speed and programmable actuations for a disulfide crosslinked thermally responsive hydrogel. The dynamic photo-activated disulfide bond exchange allows photo-mechanical programming to introduce spatio-selective network anisotropy. This gives rise to an actuation behavior dominated by thermally driven conformation change of the locally oriented polymer chains instead of the common mass-diffusion-based mechanism. With the incorporation of photothermal fillers, light-powered oscillation at frequencies as high as 1.7 Hz is realized. This, coupled with the versatility of the programming, allows access to robots with diverse high-speed motions including continuous swimming, step-wise walking, and rotating.

Effect of frother on bubble entraining particles in coal flotation

Understanding the effect of frother on bubble entraining coal particles is an important guidance for regulating coal flotation behavior. The bubble properties and the flow field surrounding the bubble were investigated using the particle image velocimetry (PIV) technique. The bubble equivalent diameter, bubble deformation rate and low-velocity region area reduced as the frother concentration increased due to a decrease in surface tension. The oscillation of the bubble and low-velocity region were subsequently analyzed. As the frother concentration increased, the oscillation frequency of the bubble and low-velocity region gradually decreased until 1.6 × 10−4 mol/L after that it tended to be stable. The oscillation amplitude of the bubble and low-velocity region slightly varied with the frother concentration but increased as the distance away from the bubble increased. The coal particle trajectories and entrainment phenomenon under the effect of frother were explored via the high-speed motion acquisition equipment. Three typical trajectories that Escape, Offset entrainment, and Entrainment were used to describe the coal particle behavior around the bubble. A predictive model of coal particle entrainment probability influenced by frothers was established. Our findings can provide valuable insight into the development of technology for mineral flotation.

A contra-rotating free-spinning energy harvester

In the field of energy harvesting from motions or vibrations, enhancing the performance of a harvester under ultralow frequency and intermittent input sources remains challenging. To address this issue, this paper presents an electromagnetic energy harvester design featuring a novel design and compact arrangement of dual one-way bearings in the magnet and coil layers. The unique one-way bearing design is capable of significantly enhancing the energy harvesting performance by eliminating springs to reduce friction for contra-rotating high-speed free-spinning motions. The devised harvester is characterised under various controlled low-frequency excitation conditions, yielding a maximum average power of 8 mW at the excitation frequency of 1 Hz. A finite element simulation is then performed to validate the performance of the energy harvester. Furthermore, with a minimized form factor, the energy harvesting capability of the proposed harvester in real-life applications of powering electronic devices is demonstrated. The innovative approach from this work holds substantial promise for high-performance energy harvesting from reciprocating motions in ultralow frequency scenarios.

Experimental Study on the Coefficient of Internal Frictional Resistance in the Annular Gap during the Plunger Gas Lift Process

Plunger gas lift process technology is an economical solution to the problem of gas well liquid buildup. However, in-house simulation experiments revealed that the high-speed movement of the plunger may lead to fluid leakage and generate annular gap frictional resistance. To address this issue, a detailed experimental study was conducted to comparatively analyze five existing frictional-resistance models, which were found to have significant deviations. Therefore, we propose a new model of annular gap frictional resistance and validate it with experimental data, and the results show that the new model is more accurate and reliable. We also conducted a comparative analysis of production-site examples by using VB programming and found that when considering the annular gap frictional resistance, the upward travel time of the plunger was delayed, the difference between the upper and lower end face pressures was significant, and the difference in speed was 1.73 m/s. This indicates that the annular gap frictional resistance cannot be ignored and is crucial for optimizing plunger gas lift process technology and improving the drainage efficiency of gas wells.

A novel coalition game based distributed cooperative content caching in mobile edge networks

In mobile edge networks with mobile vehicles, road-side units (RSUs) can be used as edge nodes to cache some popular contents for moving vehicles in advance, and therefore improving the transmission efficiency and quality of user experience during vehicle-to-infrastructure (V2I) content communication. Transferring large files to a fast-moving car is a challenging task because of the limited communication time between the vehicle and the RSU. In this paper, we propose a cooperative content placement model for RSUs, in which multiple RSUs can jointly complete the cache and transmission of large files, so that the vehicle users can obtain the target content in the process of high-speed movement. To form cooperative coalitions between RSUs and place as much content as possible, a novel coalition game based distributed cooperative content caching scheme, namely CGD3C, is proposed, in which an RSU cooperative clustering algorithm and a resource balancing based coalition formation algorithm is proposed to merge and split the coalitions, so as to obtain a stable coalition structure. Finally, a cooperative content caching determination algorithm is proposed to determine the content placement with objective of maximizing the current interests. Our simulation results show that our proposed CGD3C can achieve stable and effective content delivery for high-speed moving vehicles, form an optimal RSU coalition structure independently, as well as improve the profit by 15%, the caching resource utilization by 24%, and the request hit rate by 12% on average in comparison with existing schemes.

Effect of mechanical vibration on heat and mass transfer performance of pool boiling process in porous media: a literature review

Pool boiling in porous media has been applied in various thermal management systems by using latent heat and increasing the heat transfer area and thermal conduction path to improve the heat transfer performance. In mechanical equipment, vibration is an inevitable problem due to reasons such as engine operation and high-speed relative motion between transmission system components, which causes the system components to be affected by vibration forces or vibration accelerations. This study focuses on a review of published articles about the effects of mechanical vibration on the characteristics of boiling process in porous media by two aspects: heat transfer performance and bubble dynamics. Heat transfer coefficient (HTC) and critical heat flux are two main parameters used to measure the boiling heat transfer characteristics of porous media. For bubble dynamics investigations, properties such as migration, fragment, coalescence, departure diameter and frequency are the focus of research attention. Different mechanical vibration parameters, i.e., direction, frequency, and amplitude, will have different effects on the above characteristics. It is worth mentioning that the greatest influence occurs under resonance conditions, and this has been verified through experimental and simulation calculations. This review highlights the importance of considering mechanical vibrations in the design and optimization of porous media systems for efficient heat transfer applications. Further research is warranted to explore the detailed mechanisms and optimize the vibration parameters for enhanced heat transfer performance in thermal management systems using porous media.

A novel spaceborne ISAR imaging approach for space target with high-order translational motion compensation and spatial variant MTRC correction

ABSTRACT For spaceborne ISAR imaging of space targets, due to the high-speed relative motion between the radar and targets, both the translational and rotational motion exhibit the high-order characteristics. Conventional translational motion compensation (TMC) methods are ineffective in handling such high-order translational motion. Moreover, the migration through resolution cell (MTRC) stems from the presence of the high-order spatial variant phase of the echo signal, resulting in severe defocusing of ISAR images. In this paper, a novel spaceborne ISAR imaging approach for space targets is proposed, which incorporates the high-order TMC and the high-order MTRC correction. First, the slant range model for spaceborne ISAR imaging is derived as a third-order polynomial form. Based on this model, a modified high-order TMC method is proposed, which utilizes the minimum entropy method combined with the Broyden – Fletcher – Goldfarb – Shanno (BFGS) algorithm. The proposed method leverages orbital model information to obtain the initial TMC coefficients, enabling TMC to be completed more accurately and effectively. Then, a modified polynomial keystone transform (PKT) is proposed to correct the high-order MTRC. The PKT-based method effectively addresses both the high-order and first-order MTRC corrections simultaneously. Finally, a spaceborne ISAR imaging approach is proposed to obtain well-focused ISAR images. Simulated and real data results validate the analysis of the spaceborne ISAR imaging model and demonstrate the effectiveness of the spaceborne imaging approach for space targets proposed in this paper.

SODFormer: Streaming Object Detection With Transformer Using Events and Frames.

DAVIS camera, streaming two complementary sensing modalities of asynchronous events and frames, has gradually been used to address major object detection challenges (e.g., fast motion blur and low-light). However, how to effectively leverage rich temporal cues and fuse two heterogeneous visual streams remains a challenging endeavor. To address this challenge, we propose a novel streaming object detector with Transformer, namely SODFormer, which first integrates events and frames to continuously detect objects in an asynchronous manner. Technically, we first build a large-scale multimodal neuromorphic object detection dataset (i.e., PKU-DAVIS-SOD) over 1080.1 k manual labels. Then, we design a spatiotemporal Transformer architecture to detect objects via an end-to-end sequence prediction problem, where the novel temporal Transformer module leverages rich temporal cues from two visual streams to improve the detection performance. Finally, an asynchronous attention-based fusion module is proposed to integrate two heterogeneous sensing modalities and take complementary advantages from each end, which can be queried at any time to locate objects and break through the limited output frequency from synchronized frame-based fusion strategies. The results show that the proposed SODFormer outperforms four state-of-the-art methods and our eight baselines by a significant margin. We also show that our unifying framework works well even in cases where the conventional frame-based camera fails, e.g., high-speed motion and low-light conditions. Our dataset and code can be available at https://github.com/dianzl/SODFormer.

Порівняльний аналіз показників загальної фізичної підготовленості кваліфікованих боксерів різних манер ведення поєдинку

Purpose: to carry out a comparative analysis of indicators of the general physical fitness of skilled boxers of different manners of conducting a fight. Material and methods. The following research methods were used in the work: theoretical analysis and generalization of scientific and methodical literature; pedagogical research; pedagogical testing; methods of mathematical statistics. The research was conducted on the basis of Children and Youth Sports School № 9 (Kharkiv) and Children and Youth Sports School № 2 (Poltava). The research involved 25 skilled boxers aged 17-19 years old, of different manners of conducting a fight. The sportsmen were divided into 3 groups according to the manners of conducting a fight: «game players» (7 boxers), «tempo boxers» (12 boxers), «power players» (6 boxers). Physical abilities of boxers were tested according to the curriculum for children's and youth sports school in boxing. Results: the results of indicators in testing «Running on 1000 m» between «game players» and «power workers» are reliable (t=2,49; p<0,05), between «power workers» and «tempo workers» there is also a statistically significant difference (t=3,16; p<0,01), between indicators of «game players» and «tempo workers» reliability was not observed (t=1,10; p>0,05). In indicators of the test «Running on 100 m» between «game players» and «power players» the statistically significant difference is observed (t=2,22; p<0,05), between «power players» and «tempo players» also the statistically significant difference is observed (t=4,59; p<0,001), between indicators of «game players» and «tempo players» the reliability is not observed (t=1,39; p>0,05). In the test results of the test «Shuttle run 4×9 m» between «players» and «power men» there is a statistically significant difference (t=3,20; p<0,01), in «powermen» and «tempo men» the result was less expressed (t=2,08; p<0,05), between indicators of «players» and «tempo men» reliability was not observed (t=1,08; p>0,05). When performing the test «Hang on bent arms (angle at the elbow 900)» only «power» and «tempo» boxers had reliability (t=3,04; p<0,01), in all other boxers of different manners of conducting a fight reliability of indicators was not observed (p>0,05). In the results of testing «Torso tilt forward from a sitting position» a statistically reliable indicator was observed only between «game players» and «power men» (t=2,35; p<0,05), «power men» and «tempo men» (t=2,22; p<0,05). Conclusions. The conducted research allowed to establish that sportsmen of «power» manner of conducting a fight have more expressed high-speed and power preparation, but do not have significant results in power endurance. Athletes of the «tempo» manner have more pronounced results in high-speed movements and in endurance exercises. Sportsmen of the «game» manner of conducting a fight have the best indicators in all tests as evidenced by the obtained results.

Examination of Thinning Inspection Method for Ferromagnetic Steel Tubes Using Velocity Effect of Static Magnetic Field

The high-speed movement of an electromagnetic sensor comprising static excitation and detection coils in a steel tube generates an eddy current in the tube. The presence of a defect in the steel tube may be detected via changes in the eddy current. In general, the ferromagnetic heat transfer tubes in oil and chemical plants are inspected for defects by moving an internally inserted electromagnetic sensor at a high speed of 1 m/s. Although previous studies have focused on the detection of localized thinning in the steel tube, there are no reports on a wide range of thinning in the steel tube. Therefore, this study investigated a thickness measurement method for a wide range of thinning in the steel tube using only static magnetic field. Consequently, the possibility of measuring the thickness in the steel tube based on the flux density inside the detection coil of the proposed static magnetic inspection sensor moving at 1 m/s was demonstrated. The flux density in the steel tube was evaluated by the three-dimensional nonlinear finite element method considering the velocity effect.

Effect of hydroxyl position in reagent molecule on coal dust dedusting

Using the high-speed motion acquisition system, we studied the adhesion ability and wetting ability of coal dust under the effect of four octanol solutions. The adhesion ability followed the order: 2-Octanol > 4-Octanol > 1-Octanol > 3-Octanol. The wrap angle of coal dust on the octanol surface exhibited an increasing trend with the rise in coal proportion of dust. The observed behavior was substantiated by the interaction force, ascertained through molecular dynamic simulations. The interaction force between coal dust and 3-Octanol was the smallest leading to the weakest adhesion ability by the 3-Octanol solution. The contact angle of octanol solution droplet at the coal dust surface under the same octanol concentration was investigated to follow the order: 2-Octanol > 4-Octanol > 1-Octanol > 3-Octanol. The wetting velocity decreased as the coal proportion of dust increased. The wetting ability followed the order: 2-Octanol < 4-Octanol < 1-Octanol < 3-Octanol. The surface energy of dust increased as the coal proportion decreased. The dedusting efficient under the effect of octanols depended on the difference in surface energy between the coal dust and the octanol solution. The greater the Δγ (difference between the surface energy of the dust and solution), the weaker the adhesion ability, and the stronger the wetting ability. The findings of our study can offer valuable insights for the development of dedusting reagent design.

Structural Stability Analysis of Underwater High-Speed Moving Vehicles in Supercavity Flow Velocity

The purpose of this paper is to analyze the structural stability of an underwater high-speed vehicle. The drag characteristics of a moving body moving at high speed in water were analyzed, and a stability analysis of the structure was performed by applying the non-conservative property according to the driven force in a rocket propulsion environment. To this end, the fluid characteristics that enable high-speed maneuvering in an underwater environment were described, and the structural stability was analyzed by simplifying modeling by increasing the resulting drag. In addition, for high-speed underwater movement, an analysis of the following force according to drag and axial load and the effect on structural stability was conducted by simplifying the structure attached to a specific location when a supercavitation occurs.

Innovative technique of combined use of tennis balls, rubber bands and jumping exercises in the training process of badminton players aged 14-15

Background. The use of effective sports equipment helps players to improve their game, provides comfort and safety during the game, and also contributes to the improvement of badminton players' sports skills. Purpose: to develop and experimentally substantiate the use of exercise complexes with the use of tennis balls, rubber bands, and a jar with feather flounces in the educational and training process of young badminton players. Material and Methods. 20 badminton players athletes of the sports school "DOR" in Dnipro aged from 13 to 14 years old. Control group (10 people), experimental group (10 people). All participants and their parents agreed to participate in the experiment. The experiment was conducted from February to July 2023. Research methods: analysis of scientific and methodological sources, testing of physical qualities (long jump from a place with the right and left side, plank with a weighting, push-up, 30 s, jumps with a rope for 1 min, jumps with rotation of a rope forward, raising of a trunk in a saddle for 1 min), technical capabilities (test «Speedy movement», test «Transfer of flounces diagonally», test «Reaction», test «Smash with finishing», test «The maximum number of strokes in a draw»), methods of mathematical statistics. Results. The experimental group used a combination of exercises using tennis balls, rubber bands and jumps to develop physical qualities and technical capabilities. The control group used exercises without equipment. The results of the experiment confirmed that the control group showed significant improvement in two physical fitness tests: «Jumping rope in 1 min» and «Throwing a stuffed ball 1 kg» (p&lt;0.05; p&lt;0.01). The experimental group also showed significant improvement in two physical fitness tests: «Jumping rope for 1 min» and «Raising the body in a sit-up for 1 min», as well as in three tests of technical fitness: «High-speed movement», «Diagonal transfer of flounces» and «Smash with finishing» (p&lt;0.05; p&lt;0.01). Analysing the obtained results, significant differences between the control and experimental groups were revealed. In particular, in the experimental group there were significantly higher values in the tests «Mix with finishing» and «Maximum number of blows»in comparison with sportswomen of the control group (p &lt; 0.05). Conclusions. The complexes of exercises which include the use of sports equipment are developed and included into the training programme of badminton players of 13-14 years old. It is recommended to use exercises with tennis balls, rubber tape, jumping exercises for improvement of physical and technical fitness of young badminton players.

Design and Analysis of the High-Speed Underwater Glider with a Bladder-Type Buoyancy Engine

This study entailed the design and analysis of a 400 m class underwater glider operated by a bladder-type buoyancy engine. The underwater glider was designed for high-speed movement with a maximum velocity of 2 knots. The shape of the hull was designed to reduce water resistance using the Myring hull profile equation. The reliability was verified by performing simulations using resistance coefficients. The relationship between the control value of the ballast discharged from the buoyancy engine and the glider’s speed according to the path angle was analyzed. Further, the relationship between the optimal glide angle and the design control value of the ballast was derived, and the optimal glider speed was estimated accordingly. Based on the analysis results, a bladder-type buoyancy engine was developed, and the maximum speed of the tested underwater glider was measured via sea trials.

Synthetic Carvacrol Derivatives for the Management of Solenopsis Ants: Toxicity, Sublethal Effects, and Horizontal Transfer

Ants belonging to the genus Solenopsis are highly significant invasive pests worldwide. The control of these insects has historically relied on the use of synthetic insecticides, which, unfortunately, has led to a range of ecological repercussions. In light of these challenges and the limited availability of registered products for managing these pests, our study set out to synthesize and assess the insecticidal properties of carvacrol derivatives. The lethal and sublethal effects caused by these derivatives were compared to the essential oil of Lippia gracilis (50.7% carvacrol) and to the base molecule—carvacrol. Carvacryl benzoate was the most toxic derivative to Solenopsis sp., with an LD50 of 3.20 μg/ mg. This compound was about 2 and 7.6 times more toxic than carvacrol at the doses needed to kill 50 and 90% of populations, respectively. The workers of Solenopsis sp. showed a rapid reduction in survival when exposed to carvacrol (LT50 = 8.43 h) and carvacryl benzoate (LT50 = 8.87 h). Insects treated with sublethal doses of the compounds did not show significant effects on self-cleaning, allogrooming and aggregation, with the exception of those treated with L. gracilis essential oil. The oil increased self-cleaning and reduced allogrooming and aggregation. Ants treated with carvacrol and carvacryl benzoate travelled greater distances and had higher movement speeds when compared to the control. These compounds exhibited decreased meanders and angular velocities. When live workers were exposed to dead individuals at the LD90 of the compounds, carvacryl benzoate was the derivative that most reduced survival due to horizontal transfer. These findings underscore the considerable potential of carvacrol derivatives, specifically carvacryl benzoate, as an alternative approach to managing ants of the Solenopsis genus.

Design and experiment of a centrifugal filling and cleaning high-speed precision seed metering device for maize

In this paper, a centrifugal filling and cleaning high-speed precision seed metering device for maize is designed based on the principle of centrifugal force generated by high-speed circular motion of seeds. Through theoretical analysis and calculation, the seeding tray and front shell of the seed metering device are designed so that the seeds can use centrifugal force for filling, cleaning, releasing, and returning. The seed metering device has a simple structure and can perform high-speed and precise seeding. A response surface experiment of central composite design was conducted with feeding and seeding speeds as experimental factors, and the omission rate, repeated rate, and pass rate as performance evaluation indexes. Through response surface experiment optimization, it was deduced that the highest seeding performance was achieved when the feeding and seeding speeds were 18.72 seeds/s and 15.12 km/h, respectively. Under these conditions, the omission, repeated, and pass rates were 2.21, 5.21, and 92.58%, respectively. The results of response surface experiment showed that, when the seeding speed of the centrifugal filling and cleaning high-speed precision seed metering device for maize is in the range of 10–20 km/h, the pass rate can be greater than 90%. In addition, the speed curve of feeding and seeding fitted from the bench experiment results is effective and reliable, which allows the seed metering device to achieve a precision seeding in a speed range of 10–20 km/h. The power of the air-suction seed metering device is 470.24 W when seeding at a speed of 14 km/h. Moreover, the power of the centrifugal filling and cleaning high-speed precision seed metering device is only 10.94 W when seeding at a speed of 20 km/h, and the energy consumption during seeding is much lower than that of the air-suction seed metering device, which performs cleaner production.

Collaborative caching relay algorithm based on recursive deep reinforcement learning in mobile vehicle edge network

With the rapid development of Internet of vehicles (IoV) and the continuous emergence of vehicle information applications, the demand for content in vehicle networking is growing at an alarming speed. Mobile vehicular edge caching is regarded as a promising technology in improving Quality of Service (QoS) and reducing latency. Many caching algorithms have been proposed, which usually place contents in the Road Side Units (RSUs) to provide services to users near them. However, due to the high-speed movement of vehicles and limitations of RSU coverage, caching interrupts often occur frequently, leading to a deterioration in service quality. To deal with this problem, we make full use of Vehicle-to-Vehicle (V2V) collaboration to construct a caching system which does not require RSU support, and propose a Recursive Deep Reinforcement Learning based Collaborative Caching Relay strategy (RDRL-CR). On purpose to minimize the service delay under capacity constraints, the caching problem is formulated as an integer linear programming problem, and caching decisions are achieved through partially observable Markov Decision Process (MDP). Specifically, this strategy utilizes a Graph Neural Network (GNN) to predict vehicle trajectories, and then selects vehicles that can serve as caching nodes by calculating link stability metrics between vehicles. The Long Short Term Memory (LSTM) network is embedded into a deep deterministic strategy gradient algorithm to achieve the final caching decision. Compared with existing caching strategies, the proposed caching strategy in this paper improves the caching hit rate by about 25% and reduces content access latency by about 20%.

Direct Observation of Transient Flow Kinematics of Environment-Friendly Silica-Based Alcogel at Instantaneous Gelation

This study was intended to exploit the possibility of using the quick gelation of alcogel that is induced by adding catalytic imidazole into a silicate-oligomer-based solution. For this purpose, the experimental viability of the direct observation of the gelation behavior was actually examined. The silicate oligomer, derived from tetraethyl orthosilicate hydrolyzed under an acidic condition (pH ~ 5), was used as the quickly gelling mother solution. The capability of the oligomer solution to form a non-flowable matter in only a few seconds when triggered by the addition of the catalytic solution of imidazole is promising, for example, for stabilizing a sandy ground surface, due to its simplicity. From the practical viewpoint, how long the gelation could take (=gel time) is a crucial parameter when the choice of an appropriate gelling chemical species needs to be made. Thus, this study focused its interest on as simple an experimental method as possible for evaluating the gel time of the gelling systems that actually underwent instantaneous gelation. The silicate oligomer solution was an appropriate material both in its quick gelling behavior and environmental friendliness. For such quick gelation, rheological approaches are not applicable for detecting the boundary in the mechanical properties that delineate the regime of “gel”. In this study, instead, direct observation was employed to capture the short interval during which the gelation was completed. The silicate-oligomer-based gelling solution was observed to lose its flowability within only 0.2 s, as it was seen to come off the bottom of the shaken cylinder at 5 Hz. For a more quantitative estimation, the same gelling solution was observed by high-speed motion picture. The high-speed motion picture could clearly capture the instantaneous gelation as a sudden arrest of the flow. The sub-millisecond direct observation of the gelation behavior revealed that the timescale of the instantaneous termination of the flow was as quick as 1 ms in order of magnitude. Such instantaneous gelation in the sub-millisecond-order timescale could not be forecasted from the observable megascopic gelation, which appeared to last from 102 ms to 103 ms in our naked-eye observation. The noteworthy gap between the timescale of the naked-eye-observed gelation and that of the true gel time at a localized spot determined by the high-speed motion picture should be noted to avoid excess agitation, which can result in total collapse into gel fragments of the just solidifying or already solidified gel under strong deformational influence by mechanical agitation, for example.

Dynamic modeling and robust vibration control of a high-speed macro-micro gripping system

This paper presents dynamic modeling and robust vibration control for a high-speed macro–micro gripping system comprised of an air-floating macro-positioning stage and a compliant piezoelectric microgripper. A dynamic displacement coupling model is established considering rigid-flexible coupled macro-micromechanical structures, electromechanical properties containing the piezoelectric actuator and power amplifier, and hysteresis nonlinearity. Then, a comprehensive position/force model is proposed by integrating displacement, load, and force characteristics to describe the position and gripping force of micro-objects. Regarding system disturbances and model uncertainties, robust control strategies for pure displacement and position/force cooperation are devised utilizing perturbation H∞ controllers and Kalman filters. Experimental results indicate that measurement noises for pure displacement and position/force are effectively reduced. Position/force disturbances arising from sudden mutual changes are decreased from 14.39 μm and 7.25 mN to 0.82 μm and 0.85 mN. Also, position/force vibrations excited by high-speed macro motion are suppressed by 31.99 % and 58.06 %. Both precision tracking and vibration suppression are still well achieved, even at significant parameter perturbation. Thus, experiments verify the feasibility of the proposed control strategy.

Deep-Inspiration Breath-Hold Stereotactic Body Radiation Therapy by Combining Spirometer-Guided Breath-Hold and a Real-Time Tumor Tracking System: A Novel Approach

There are several methods used against respiratory motion (RM). Expiratory breath-hold (BH) is considered more stable and reproducible than inspiratory BH; therefore, BH with spirometry is often used for expiration. The real-time tumor tracking radiotherapy (RTRT) system is a highly effective method for reducing the margin of RM. This system ambushes and irradiates tumors during the expiratory phase when tumors move slowly. Although these methods usually involve expiration, it is advantageous to expand the lungs with inspiration to reduce the risk of adverse events. Here, we developed a new approach of performing stereotactic body radiation therapy (SBRT) under deep-inspiration BH (DIBH) by combining these two methods. Lung tumors with respiratory motion ≥ 1 cm were included. Three or four fiducial markers were placed near the tumor via bronchoscopy. DIBH CT (CT-IN) was performed under the guidance of spirometer. The PTV was obtained by adding a 5-mm margin to the GTV delineated on CT-IN. The prescribed dose was 42 Gy in four fractions for the D95 of the PTV. An error of 2.0 mm around the planned position of the fiducial marker on CT-IN was permitted along each orthogonal axis as a gating box. In preparation for cases in which the reproducibility of DIBH is low and treatment cannot be performed, light expiration BH CT (CT-EX) was also performed, and a radiotherapy plan was prepared for the conventional RTRT system so that it could be switched at any time. Lung volumes and doses (mean dose, V20 Gy, V10 Gy, and V5 Gy) on CT-EX and CT-IN were compared. Five patients underwent SBRT with DIBH, and all completed the planned irradiation course. The median treatment time per fraction was 27.86 min (range, 25.5-40.6). Four tumors were located in the left lower lobe and one in the right lower lobe. The median volume of PTV was 12.4 (range, 5.2-26.2) mL. The lung volumes and doses on CT-EX and CT-IN are shown in the Table. The lung volume on CT-IN was 1.6 times larger than that on CT-EX. The PTV-to-lung ratio on CT-IN was significantly lower than that on CT-EX. V20 Gy and V10 Gy on CT-IN were significantly lower than those on CT-EX. SBRT with DIBH was achieved by combining the spirometer and RTRT system. This can help to eliminate concerns about reproducibility and high-speed tumor movement during inspiration, which are weaknesses of spirometer-guided breath-hold and the RTRT system, respectively, while ensuring the accuracy of the RTRT system. DIBH SBRT is a promising method that can reduce lung dose.