Large Acceleration Research Articles

Efficient algorithm for tracking the single target applied to optical-phased-array LiDAR.

A centroid dynamic programming track-before-detect algorithm is proposed, which is applied for tracking the moving target with an unknown speed. Using the inertialess scanning based on an optical phased array, the experimental tracking system is established, and the obtained maximum signal-to-noise ratio is 9.97 dB. Targets of different motion states can be accurately tracked with this algorithm. In addition, we innovated the original track-before-detect algorithm by adding the variable step, so that the target with large accelerations can be tracked accurately. The accuracy of our proposed algorithm is verified numerically and experimentally, which shows that our algorithm can be used to track the target trajectory effectively, and the error in extracting the target velocity is below 2%.

Simultaneous realization of high d and large strain in (K,Na,Li) (Nb,Sb)O3-(Ca,Sr)ZrO3 materials and their application in piezoelectric actuators

A pseudocubic-tetragonal-orthorhombic (PC-T-O) multi-structure was developed in the 0.96(K 0.5 Na 0.47 Li 0.03 ) (Nb 0.92 Sb 0.08 )O 3 -0.04(Ca 0.5 Sr 0.5 )ZrO 3 [(KN 0.47 L 0.03 )NS-CSZ] lead-free piezoceramic. The PC structure observed in this sample was deemed to have an R3m rhombohedral structure. This sample demonstrated a large d 33 (560 pC/N) owing to the existence of the PC-T-O multi-structure. The (KN 0.47 L 0.03 )NS-CSZ thick film also exhibited a large d 33 (560 pC/N) and strain (0.19% at 4.0 kV/mm). The large strain was sustained even after the application of 10 6 electric-field cycles. Therefore, the (KN 0.47 L 0.03 )NS-CSZ thick film exhibited excellent fatigue characteristics and was utilized to fabricate a planar-type actuator, which achieved a large displacement (300 μm) and acceleration (872 G) at 125 V/mm. A cantilever-type multilayer actuator was also prepared using five layers of the (KN 0.47 L 0.03 )NS-CSZ thick film and demonstrated a large displacement (3500 μm) and acceleration (42.96 G) at 250 V/mm. Therefore, the (KN 0.47 L 0.03 )NS-CSZ thick film is a good candidate for fabricating various piezoelectric actuators.

Multivariable Adaptive Super-Twisting Guidance Law Based on Barrier Function

For tactical missiles, sliding mode control and super-twisting algorithms have been widely studied in the area of guidance law design. However, these methods require the information of the target accelerations and the target acceleration derivatives, which is always unknown in practice. In addition, guidance laws utilizing these tools always have chattering phenomena and large acceleration commands. To solve these problems, this article introduces a barrier function based super twisting controller and expands the controller to a multivariable adaptive form. Consequently, a multivariable adaptive super-twisting guidance law based on barrier function is proposed. Moreover, the stability of the guidance law is analyzed, and the effectiveness and the robustness are demonstrated by three simulation examples. Compared with previous guidance laws using sliding mode control or super-twisting algorithm, the one proposed in this paper does not require the information of target accelerations, nor target acceleration derivatives; it has smaller super-twisting gains so that has smaller acceleration commands; it can increase and decrease the gains to follow the target accelerations and maintain the sliding mode, and it does not chatter.

Use of accelerometers to assess and describe trailer motion and its impact on carcass bruising in market cows transported under North American conditions.

Increased trailer motion, coupled with large accelerations and decelerations, has been associated with decreased carcass quality and increased stress indicators in cattle, sheep, and hogs. However, motion of livestock trailers has not been measured in North-American cattle semi-trailers over long distances (> 1000 km). The objectives of this study were to develop a practical method of measuring transport trailer accelerations, to describe the range of accelerations cattle are exposed to under North American conditions, and to conduct a preliminary analysis of trailer accelerations for each compartment and its effect on carcass bruising. The root mean square (RMS) of acceleration was measured at a sampling rate of 200 Hz in 3 orthogonal axes; x (vertical), y (front-to-rear), and z (lateral; side-to-side) by clamping an accelerometer to the cross beam below each of the five compartments of 8 trailers transporting a total of 330 animals (674 ± 33.3 kg BW) from an assembly yard to a processing facility. Journeys took place on separate days and ranged in duration from 13 to 15.7 h. The number and severity of bruises per carcass were determined prior to trimming for n = 290 carcasses and the number of bruises per carcass ranged between 0.38 and 12.75, whereas the bruising score per carcass ranged between 0.38 and 14.88. Mean number of bruises and severity of bruises (bruising scores were assigned according to size using a three-point scale: 1) ≤ 6.5 cm, 2) 6.5 to 12 cm, and 3) ≥ 12 cm and bruising severity was determined by applying the weighted score to each bruise according to bruise area) per carcass was 4.52 ± 2.43 (n) and 5.31 ± 2.84, respectively. Accelerations in commercial transport vehicles were found to range between 0.33 and 1.90 m/s2, whereas the mean RMS of acceleration for all trailers (n = 31 accelerometers) was 1.01 ± 0.32 m/s2, 0.72 ± 0.31 m/s2, and 0.97 ± 0.30 m/s2 for the x, y, and z axes, respectively. Horizontal acceleration was greatest in the nose, back, and doghouse compartments (P = 0.05), whereas lateral acceleration was greatest in the nose and back compartments (P = 0.08). Although the nose, back, and doghouse compartments had the highest RMS values for the lateral and horizontal axes, there were no significant relationships between bruising and acceleration. Replication of this research is required to further understand the relationships between trailer motion, carcass bruising, and overall animal welfare in cattle transported long distances.

Three-dimensional analysis of eccentric pounding between two-storey structures using explicit non-smooth dynamics

Pounding research has been gaining momentum in the last decades with large earthquakes hitting cities with insufficiently separated buildings. Even if no major structural damage may be observed in the case of slab–slab pounding, large acceleration pulses may influence the response of equipment and cause disruption in their functionality. In this work, two different models are set up for reproducing shake table tests concerning two-storey adjacent structures, with slab–slab pounding. For the slab representation, the first model uses hexahedral finite elements, while the second one uses shell elements. One of the main objectives of the study is to predict the floor response spectra over a broad frequency range, up to 400Hz. Transient computations of the pounding problem under earthquake excitation are carried out using the explicit CD-Lagrange approach. Rayleigh damping is employed to filter out the spurious high frequency oscillations. The comparison between numerical and experimental results in terms of displacements and floor acceleration spectra shows that the numerical models are able to reproduce the eccentric pounding during the shake table tests. No parameter adjustment related to the contact is required underlining the robustness of the approach.

Protein-Ribofuranosyl Interactions Activate Orotidine 5'-Monophosphate Decarboxylase for Catalysis.

The role of a global, substrate-driven, enzyme conformational change in enabling the extraordinarily large rate acceleration for orotidine 5'-monophosphate decarboxylase (OMPDC)-catalyzed decarboxylation of orotidine 5'-monophosphate (OMP) is examined in experiments that focus on the interactions between OMPDC and the ribosyl hydroxyl groups of OMP. The D37 and T100' side chains of OMPDC interact, respectively, with the C-3' and C-2' hydroxyl groups of enzyme-bound OMP. D37G and T100'A substitutions result in 1.4 kcal/mol increases in the activation barrier ΔG⧧ for catalysis of decarboxylation of the phosphodianion-truncated substrate 1-(β-d-erythrofuranosyl)orotic acid (EO) but result in larger 2.1-2.9 kcal/mol increases in ΔG⧧ for decarboxylation of OMP and for phosphite dianion-activated decarboxylation of EO. This shows that these substitutions reduce transition-state stabilization by the Q215, Y217, and R235 side chains at the dianion binding site. The D37G and T100'A substitutions result in <1.0 kcal/mol increases in ΔG⧧ for activation of OMPDC-catalyzed decarboxylation of the phosphoribofuranosyl-truncated substrate FO by phosphite dianions. Experiments to probe the effect of D37 and T100' substitutions on the kinetic parameters for d-glycerol 3-phosphate and d-erythritol 4-phosphate activators of OMPDC-catalyzed decarboxylation of FO show that ΔG⧧ for sugar phosphate-activated reactions is increased by ca. 2.5 kcal/mol for each -OH interaction eliminated by D37G or T100'A substitutions. We conclude that the interactions between the D37 and T100' side chains and ribosyl or ribosyl-like hydroxyl groups are utilized to activate OMPDC for catalysis of decarboxylation of OMP, EO, and FO.

Unsteady aerodynamics of a model bristled wing in rapid acceleration motion

Tiny insects with bristled wings perform the “rowing” motion: the wings accelerate rapidly from zero-velocity to certain reference velocity at 90° angle-of-attack, and the drag produced in this motion provides the weight-supporting force. A flat-plate wing will produce a large drag in such a motion, but it is unknown whether a bristled wing could do so. Here, we study this problem using numerical simulation and simple model wings. The acceleration is large: the wing translates only about half the wing chord length to reach the reference velocity. The following is shown. The bristled wing can produce a very large unsteady drag peak and large time-averaged drag as a flat-plate wing does; the time-averaged drag is about 2.5 times as large as the quasi-steady value. The force production mechanisms are different between the two wings: for the flat-plate wing, because of the large acceleration, the added-mass and the strong free vorticity in the flow produce a large pressure difference between the windward and leeward surfaces of the plate, resulting in large drag (surface frictional force has negligible contribution). Yet for the bristled wing, although the acceleration of the wing is large, a bristle needs to translate about 80 diameters to reach the reference velocity; thus, the effect of acceleration is very weak. Each bristle operates in a quasi-steady Stokes flow and the large drag of the bristled wing is due to the very large surface pressure and frictional forces on each bristle, generated by the strong viscous effect of the Stokes flow (the drag is equally contributed by the surface pressure and frictional forces).

Penrose Process: Its Variants and Astrophysical Applications

We present a review of the Penrose process and its modifications in relation to the Kerr black holes and naked singularities (superspinars). We introduce the standard variant of this process, its magnetic version connected with magnetized Kerr black holes or naked singularities, the electric variant related to electrically charged Schwarzschild black holes, and the radiative Penrose process connected with charged particles radiating in the ergosphere of magnetized Kerr black holes or naked singularities. We discuss the astrophysical implications of the variants of the Penrose process, concentrating attention to the extreme regime of the magnetic Penrose process leading to extremely large acceleration of charged particles up to ultra-high energy E∼1022 eV around magnetized supermassive black holes with mass M∼1010M⊙ and magnetic intensity B∼104 G. Similarly high energies can be obtained by the electric Penrose process. The extraordinary case is represented by the radiative Penrose process that can occur only around magnetized Kerr spacetimes but just inside their ergosphere, in contrast to the magnetic Penrose process that can occur in a more extended effective ergosphere determined by the intensity of the electromagnetic interaction. The explanation is simple, as the radiative Penrose process is closely related to radiated photons with negative energy whose existence is limited just to the ergosphere.

Structural and piezoelectric properties of textured NLKNS‐CZ thick films and their application in planar piezoactuator

Abstract0.97(Na0.5‐xLixK0.5)(Nb0.89Sb0.11)O3‐0.03CaZrO3 [(N0.5‐xLxK)(NS)‐CZ] piezoceramic (x = 0.325) has a pseudocubic‐tetragonal‐orthorhombic (PC‐T‐O) multi‐structure. The PC structure formed in this piezoceramic was identified as the R3m rhombohedral structure. This piezoceramic showed the large piezoelectric charge constant (d33) of 515 pC/N due to the PC‐T‐O multi‐structure. The NaNbO3 (NN) templates were used to texture the (N0.5‐xLxK)(NS)‐CZ thick films along the (001) direction, and the textured thick film (x = 0.0375) had a large Lotgering factor of 95.6%. The PC‐T‐O multi‐structure was observed in this thick film (x = 0.0375), but the thick film (x = 0.0325) showed a PC‐O structure owing to the diffusion of the NN templates into the thick film. The textured thick film (x = 0.0375) exhibited an increased d33 of 625 pC/N because of the PC‐T‐O multi‐structure and the lineup of grains along the [001] direction. A textured thick film (x = 0.0375) was used to fabricate a planar‐type actuator to confirm its applicability to electrical devices. This actuator exhibits large acceleration (580.3 G) and displacement (150 μm) at a low electric field of 0.2 kV/mm with a short response time of 3.0 ms. Therefore, the (N0.5‐xLxK)(NS)‐CZ thick films are excellent lead‐free piezoceramics.

High Efficiency Uniform Wakefield Acceleration of a Positron Beam Using Stable Asymmetric Mode in a Hollow Channel Plasma.

Plasma wakefield acceleration in the blowout regime is particularly promising for high-energy acceleration of electron beams because of its potential to simultaneously provide large acceleration gradients and high energy transfer efficiency while maintaining excellent beam quality. However, no equivalent regime for positron acceleration in plasma wakes has been discovered to date. We show that after a short propagation distance, an asymmetric electron beam drives a stable wakefield in a hollow plasma channel that can be both accelerating and focusing for a positron beam. A high charge positron bunch placed at a suitable distance behind the drive bunch can beam-load or flatten the longitudinal wakefield and enhance the transverse focusing force, leading to high efficiency and narrow energy spread acceleration of the positrons. Three-dimensional quasistatic particle-in-cell simulations show that an over 30% energy extraction efficiency from the wake to the positrons and a 1% level energy spread can be simultaneously obtained. Further optimization is feasible.

Gas-filled capillary-discharge stabilization for plasma-based accelerators by means of a laser pulse

The development of compact accelerator machines is leading towards the use of plasma-based devices that are able to sustain large acceleration gradients up to several tens of GV m−1. The main issue, in this regard, is due to the necessity to produce the plasma shot-by-shot starting from neutral gases, since its lifetime is limited to a few tens of microseconds. This puts severe limitations on its resulting uniformity, stability and reproducibility, which in turn strongly affects the quality of accelerated beams by plasmas. In this work, we describe a gas-filled discharge-capillary where the plasma generation, achieved by ionizing Hydrogen gas with a high-voltage electrical discharge, is stabilized by triggering its ignition with an external laser pulse. Results show a noticeable stabilization of the resulting plasma density along the capillary and the discharge pulse. This enables the development of very long capillaries and in turn, acceleration lengths as required, for instance, by next-generation plasma-based facilities delivering beams in the GeV-scale.

The “striated delta” signature of gravity waves generated near the jet stream during rapid extratropical cyclogenesis

AbstractDistinctive, triangular‐shaped “striated delta” clouds provide a novel framework for better understanding large‐amplitude gravity wave generation near upper‐tropospheric jets and fronts during rapid extratropical cyclogenesis, as the transverse cloud‐top banding is thought to be the imprint of gravity waves. For 28 striated deltas in the Australian region between May and September 2009, cloud formations have a mean length of 1,034 km, width of 537 km, lifetime of 7 hr and striation wavelength of 74 km. Composite analysis in ECMWF operational analysis data shows that deltas typically occur within the poleward jet exit during baroclinic evolution, located near the axis of inflection between an upstream upper trough and downstream ridge. Candidate gravity wave generation mechanisms in the vicinity of the upper jet coinciding with striated delta development are examined, including large parcel accelerations, nonlinear imbalance within the broadscale flow and deep moist convection. The striated delta shape is partly explained by a triangular pattern of Q‐vector convergence and quasi‐geostrophic adiabatic vertical motion forcing within the poleward jet exit, although the pattern is displaced a few hundred kilometres upstream.

Entanglement dynamics for Unruh-DeWitt detectors interacting with massive scalar fields: the Unruh and anti-Unruh effects

We study, in the framework of open quantum systems, the entanglement dynamics for a quantum system composed of two uniformly accelerated Unruh-Dewitt detectors interacting with a bath of massive scalar fields in the Minkowski vacuum. We find that the entanglement evolution for the quantum system coupled with massive fields is always slower compared with that of the one coupled with massless fields, and this time-delay effect brought about by the field being massive can however be counteracted by a large enough acceleration, in contrast to the case of a static quantum system in a thermal bath, where this time delay is not affected by the temperature. Remarkably, the maximal concurrence of the quantum system generated during evolution may increase with acceleration for any inter-detector separation while that for static ones in a thermal bath decreases monotonically with temperature, and this can be considered as an anti-Unruh effect in terms of the entanglement generated.

Analisa Karakteristik Getaran Pada Mesin Asphalt Mixing Plant Tipe Apollo ANP- 1500 Berdasarkan Kapasitas Pembuatan Aspal Jalan Pada Daerah Horizontal, Vertikal Dan Longitudinal Berdasarkan Time Domain

Asphalt mixing plant machine is a tool used to process several materials into road asphalt, where it is necessary to know how to analyze the vibration characteristics of the asphalt mixing plant machine based on the capacity of making asphalt road in horizontal, vertical and longitudinal areas based on the time domain. The research method is carried out by collecting data on the amount of deviation, speed and acceleration that arise due to the processing of several materials so as to produce road asphalt based on differences in the capacity of different asphalt processed. Based on the measurement results, it is found that the highest vibration occurs at the asphalt mixing plant machine seat for a capacity of 60 tons/hour where the magnitude of the deviation is 0.222 mm in the horizontal direction at 100 seconds, the largest velocity is 11.99 mm/s horizontally in the second 40 mm/s and the largest acceleration is 369.7 mm/s2 in the horizontal direction of the 20th second. According to the ISO IS 2372 standard, the vibration of the Apollo ANP-1500 asphalt mixing plant machine enters class IV with a generator capacity above 75 KW, to be more precise (150KVA = 120KW). Then it can be analyzed that the generator vibration falls into the category of "vibration within tolerance limits and is only operated for a limited time" where the highest speed is 11.99 mm/s.

Machine Learning to Improve Orientation Estimation in Sports Situations Challenging for Inertial Sensor Use.

In sports, inertial measurement units are often used to measure the orientation of human body segments. A Madgwick (MW) filter can be used to obtain accurate inertial measurement unit (IMU) orientation estimates. This filter combines two different orientation estimates by applying a correction of the (1) gyroscope-based estimate in the direction of the (2) earth frame-based estimate. However, in sports situations that are characterized by relatively large linear accelerations and/or close magnetic sources, such as wheelchair sports, obtaining accurate IMU orientation estimates is challenging. In these situations, applying the MW filter in the regular way, i.e., with the same magnitude of correction at all time frames, may lead to estimation errors. Therefore, in this study, the MW filter was extended with machine learning to distinguish instances in which a small correction magnitude is beneficial from instances in which a large correction magnitude is beneficial, to eventually arrive at accurate body segment orientations in IMU-challenging sports situations. A machine learning algorithm was trained to make this distinction based on raw IMU data. Experiments on wheelchair sports were performed to assess the validity of the extended MW filter, and to compare the extended MW filter with the original MW filter based on comparisons with a motion capture-based reference system. Results indicate that the extended MW filter performs better than the original MW filter in assessing instantaneous trunk inclination (7.6 vs. 11.7° root-mean-squared error, RMSE), especially during the dynamic, IMU-challenging situations with moving athlete and wheelchair. Improvements of up to 45% RMSE were obtained for the extended MW filter compared with the original MW filter. To conclude, the machine learning-based extended MW filter has an acceptable accuracy and performs better than the original MW filter for the assessment of body segment orientation in IMU-challenging sports situations.

The effect of gravity on turbulence modulation in particle-laden horizontal open channel flow

Two-way coupled direct numerical simulation of turbulence in a horizontal open channel with Lagrangian tracking of heavy particles is performed to study the joint influence of particle inertia and wall-normal gravity on turbulence modulation. The Stokes numbers based on the wall units considered in the study are St+= 1 (low inertia), 31 (moderate inertia), and 202 (high inertia) and the gravitational accelerations are g+= 0, 0.0068, 0.068, and 0.2221, varying from case to case. It is found that heavy particles (gravity involved in simulation) with low inertia subtly increase or have little significant influence on turbulence modulation, regardless of gravitational acceleration. Particles with high inertia and large gravitational acceleration significantly reduce the mean streamwise fluid velocity and the scales of turbulence structure near the wall, and vice versa in the outer layer. In this case, turbulence fluctuations are notably suppressed and the turbulence structures tend to be two-dimensional and laminar due to the strong rebound and trajectory-crossing effect. Moderate-inertia particles probably cause anisotropic turbulence modulation due to the competition between particle inertia and gravity settling. In the parameter range studied in this work, particles have indistinctive modification on turbulence when τp+g+ (=St+g+)&amp;lt;0.2 but suppress turbulence when τp+g+&amp;gt;0.2.

Road type-based driving cycle development and application to estimate vehicle emissions for passenger cars in Guangzhou

Driving cycles are important parameters to estimate vehicle emissions. However, most previous driving cycles, which were developed at the city scale or even national scale, cannot resolve the emission variations affected by road types and thus might introduce large uncertainties in the emission estimation. In this study, we proposed a new approach based on road type-based (RT-based) driving cycles to improve the estimation of vehicle emissions. As a case study, RT-based driving cycles for passenger cars were developed using more than 600,000 s of GPS data collected through on-road tests in Guangzhou. Results showed that driving cycles varied across road types (urban arterial road, highway, and other urban road), which featured varied velocities, acceleration, deceleration, and driving mode percentages. The urban arterial road had the lowest velocity (18.7 km/h), but the largest creeping mode proportion (61%). The other urban road had the largest acceleration and deceleration, while the highway had the highest average velocity (43.2 km/h) but the lowest acceleration and deceleration. Evaluations revealed that RT-based driving cycles could accurately depict separate driving patterns and emission factors on different road types. In comparison, city-level driving cycles and standard driving cycles typically overestimated emission factors of highways but underestimated those of other road types in Guangzhou. Consequently, emissions of light-duty gasoline passenger cars could be underestimated by 33% in the downtown and overestimated by approximately 25% in and around the highways. This study highlights the development of RT-based driving cycles to accurately estimate vehicle emissions and characterize their spatial variations.

Analysis of the Deep Sea Mining Pipe Transverse Vibration Characteristics Based on Finite Element Method

This paper analyzes the transverse vibration laws of 5000 m ladder-shaped mining pipe under different towing velocities and accelerations in the ocean, thinking of the pipe as the beam model, discretized based on the FEM. The algorithm is used to solve the problem to obtain the transverse vibration law. The research shows that the mining pipe overall transverse vibration trend decreases first and then increases, the minimum vibration value occurs at 3000 m, and the maximum occurs at the top. Increasing the towing velocity, acceleration, and ore bin weight will increase the transverse vibration value. The vibration intensity produced by the same acceleration in the constant acceleration and deceleration stages is different, and the damping effect after adding the same damping is also different. In the range of 0.01 m/s2–0.1 m/s2, the vibration reduction effect after adding damping in the constant deceleration stage is more significant, and in the range of 0.1 m/s2-0.2 m/s2, the vibration reduction effect after adding damping in the constant acceleration stage is more significant. In the stage of the constant acceleration or deceleration, when adding the same damping, the vibration intensity generated by the large acceleration is still far greater than the vibration intensity generated by the small acceleration, so the mining ship should keep the small acceleration for towing motion.

Analysis of transient mixed elastohydrodynamic lubrication in planetary roller screw mechanism

Previous lubrication studies for planetary roller screw (PRSM) are mainly concentrated on steady-state condition without the consideration of entrainment angle. However, PRSM always operates in transient situations with frequent startup and shutdown process. In this paper, uneven friction distribution, the influence of helix angle on lubricating properties and transient behavior in the roller-screw interface are analyzed comprehensively based on transient mixed-EHL model, which considers real three-dimensional (3D) machined roughness and arbitrary entrainment velocity. The results show that smaller helix angle is beneficial to improve the lubrication performance. Increasing the rotating speed and declining axial load can moderate the uneven friction distribution. Besides, a relatively large angular acceleration may enlarge the film thickness and reduce the friction at the shut down status. The numerical simulation model can be utilized as a design optimization tool for the PRSM.

Hybrid Metachronal Rowing Augments Swimming Speed and Acceleration via Increased Stroke Amplitude.

Numerous aquatic invertebrates use drag-based metachronal rowing for swimming, in which closely spaced appendages are oscillated starting from the posterior, with each appendage phase-shifted in time relative to its neighbor. Continuously swimming species such as Antarctic krill generally use "pure metachronal rowing" consisting of a metachronal power stroke and a metachronal recovery stroke, while burst swimming species such as many copepods and mantis shrimp typically use "hybrid metachronal rowing" consisting of a metachronal power stroke followed by a synchronous or nearly synchronous recovery stroke. Burst swimming organisms need to rapidly accelerate in order to capture prey and/or escape predation, and it is unknown whether hybrid metachronal rowing can augment acceleration and swimming speed compared to pure metachronal rowing. Simulations of rigid paddles undergoing simple harmonic motion showed that collisions between adjacent paddles restrict the maximum stroke amplitude for pure metachronal rowing. Hybrid metachronal rowing similar to that observed in mantis shrimp (Neogonodactylus bredini) permits oscillation at larger stroke amplitude while avoiding these collisions. We comparatively examined swimming speed, acceleration, and wake structure of pure and hybrid metachronal rowing strategies by using a self-propelling robot. Both swimming speed and peak acceleration of the robot increased with increasing stroke amplitude. Hybrid metachronal rowing permitted operation at larger stroke amplitude without collision of adjacent paddles on the robot, augmenting swimming speed and peak acceleration. Hybrid metachronal rowing generated a dispersed wake unlike narrower, downward-angled jets generated by pure metachronal rowing. Our findings suggest that burst swimming animals with small appendage spacing, such as copepods and mantis shrimp, can use hybrid metachronal rowing to generate large accelerations via increasing stroke amplitude without concern of appendage collision.