Duty Factor Research Articles

Analysis of the DC/DC Zeta topology converter ripples by applying its limiting continuous mathematical model

Objectives. A DC/DC Zeta topology converter represents a unipolar electronic device for converting an input positive voltage into a stabilized output voltage of the same polarity, which can be set at voltages both below and above the input voltage. The aim of this work is to analyze Zeta converter circuitry, which requires the following tasks to be solved: using Kirchhoff’s Circuit Laws, obtain systems of equations describing converter operation in the phase of energy accumulation and in the phase of energy transfer; using a method proposed by A.I. Korshunov, combine the resulting systems of equations into a marginal continuous mathematical model; using expressions describing constant components of currents and voltages in Zeta converter, analyze their ripples and obtain equations for their calculation; compare the current and voltage values obtained from the continuous limiting mathematical model with the Zeta simulation results.Methods. The tasks are solved using Kirchhoff’s rules and the method for obtaining the limiting continuous mathematical model proposed by A.I. Korshunov. The results are analyzed using a circuit modelling in NI Multisim.Results. It is shown that the phase coordinates of the mathematical model tend to real values of converter currents and voltages at a switching frequency of the power switch of more than 200 kHz. A strong correspondence was established between the calculated ripple values and their values obtained in the simulation (when changing the duty factor).Conclusions. Mathematical models comprise the basis of unified calculation methods for any radio electronic circuit. The developed limiting continuous mathematical model allows a range of changes in current flowing through the choke windings and voltages on capacitor plates to be evaluated, including their maximum and minimum values for various converter parameters, such as power switch switching frequency, duty factor, element ratings, etc. Obtaining this information in turn enables the rational selection of the electronic component base of the converter.

Experimental investigation of micro-machining on borosilicate glass using mist flow aided WECDM

Wire electro-chemical discharge machining (WECDM) process is a variant of electro-chemical discharge machining process and is a novel method to machine electrically non-conductive materials. In the present research investigation, an in-house developed WECDM setup with mist flow was used to generate micro channels on borosilicate glass. The electrolyte was provided in the form of mist, formed with the combination of electrolyte and compressed air. The mist flow system was used to control the machining process that improved the stability of the spark, and flushing in the machining zone resulted in a smooth surface of machined channels. Electrolyte concentration, duty factor, wire feed rate, and mist flow rate were chosen as input process parameters, and their effect on output quality characteristics such as material removal rate and width of cut was evaluated. the performance of were during. The addition of the mist flow technique in the process resulted in an improvement in surface finish, heat affected zone (HAZ) and discharge characteristics. ANOVA analyses were carried out to obtain the significant process parameters that affected the output characteristics. Scanning electron micrograph images were captured in order to analyze the surface morphology of the machined channel and revealed thermal cracks, HAZ, irregular surface and recast layer in the samples machined with low mist flow rate as compared to samples machined using high Mist flow rates.

120 mA operation of J-PARC cesiated RF-driven H- ion source

The Japan Proton Accelerator Research Complex (J-PARC) cesiated RF-driven H- ion source (IS) has been stably operated for about eight years by using an internal-RF-antenna developed at the Spallation Neutron Source (SNS). From Sep. 2018, the J-PARC 400 MeV LINAC has been steadily operated with the design H- ion beam intensity (IH- ) of 50 mA, when an about 60 mA beam is injected from the IS. At each end of about 3 months J-PARC operation, the IS supplies a 52.5 keV 72 mA beam for the LINAC 60 mA acceleration. The IS superior emittances predicted in a test-stand were proven by the high RFQ acceleration efficiency of 94.3% (IH-RFQ = 67.9 mA). The high intensity beam with transverse emittances suitable for the RFQ is produced with several unique measures, such as, slight water molecules addition into hydrogen plasma, the low temperature (about 70°C) operation of 45°-tapered 16-mm thick plasma electrode with the precise cesium (Cs) density control, the impurity elimination in the hydrogen plasma along with the filter-field optimization, the continuous-wave igniter plasma driven with a 42-W 30-MHz RF, and so on. The 120 mA operation results of the IS in the test-stand are presented in this paper. A 69.9 keV 120 mA H- ion beam, about 107.8 mA of which was inside the transverse emittances used for a common RFQ design, was stably operated with a duty factor of 4% (1 ms × 40 Hz). The IS is the benchmark one for the next generation high energy H- LINACs aiming for 100 mA class intensity.

Dynamics and energetics of bottlenose dolphin (Tursiops truncatus) fluke-and-glide gait.

Intermittent locomotion composed of periods of active flapping/stroking followed by inactive gliding has been observed with species that inhabit both aerial and marine environments. However, studies on the energetic benefits of a fluke-and-glide (FG) gait during horizontal locomotion are limited for dolphins. This work presents a physics-based model of FG gait and an analysis of the associated cost of transport for bottlenose dolphins (Tursiops truncatus). New gliding drag coefficients for the model were estimated using measured data from free-swimming bottlenose dolphins. The data-driven approach used kinematic measurement from 84 h of biologging tag data collected from three animals to estimate the coefficients. A set of 532 qualifying gliding events were automatically extracted for estimation of the gliding drag coefficient. Next, data from 783 FG bouts were parameterized and used with the model-based dynamic analysis to investigate the cost benefits of FG gait. Experimental results indicate that FG gait was preferred at speeds of ∼2.2-2.7 m s-1. Observed FG bouts had an average duty factor of 0.45 and a gliding duration of 5 s. The average associated metabolic cost of transport (COT) and mechanical cost of transport (MECOT) of FG gait are 2.53 and 0.35 J m-1 kg-1, respectively, at the preferred speeds. This corresponded to a respective 18.9% and 27.1% reduction in cost when compared with model predictions of continuous fluking gait at the same average bout speed. Average thrust was positively correlated with fluking frequency and amplitude as animals accelerated during the FG bouts, whereas fluking frequency and amplitude were negatively correlated for a given thrust range. These results suggest that FG gait enhances the horizontal swimming efficiency of bottlenose dolphins and provides new insights into the gait dynamics of these animals.

FUS-mediated blood–brain barrier disruption for delivering anti-Aβ antibodies in 5XFAD Alzheimer’s disease mice

PurposeAmyloid-β (Aβ) peptides, the main component of amyloid plaques found in the Alzheimer's disease (AD) brain, are implicated in its pathogenesis, and are considered a key target in AD therapeutics. We herein propose a reliable strategy for non-invasively delivering a specific anti-Aβ antibody in a mouse model of AD by microbubbles-enhanced Focused Ultrasound (FUS)-mediated Blood–brain barrier disruption (BBBD), using a simple single stage MR-compatible positioning device.MethodsThe initial experimental work involved wild-type mice and was devoted to selecting the sonication protocol for efficient and safe BBBD. Pulsed FUS was applied using a single-element FUS transducer of 1 MHz (80 mm radius of curvature and 50 mm diameter). The success and extent of BBBD were assessed by Evans Blue extravasation and brain damage by hematoxylin and eosin staining. 5XFAD mice were divided into different subgroups; control (n = 1), FUS + MBs alone (n = 5), antibody alone (n = 5), and FUS + antibody combined (n = 10). The changes in antibody deposition among groups were determined by immunohistochemistry.ResultsIt was confirmed that the antibody could not normally enter the brain parenchyma. A single treatment with MBs-enhanced pulsed FUS using the optimized protocol (1 MHz, 0.5 MPa in-situ pressure, 10 ms bursts, 1% duty factor, 100 s duration) transiently disrupted the BBB allowing for non-invasive antibody delivery to amyloid plaques within the sonicated brain regions. This was consistently reproduced in ten mice.ConclusionThese preliminary findings should be confirmed by longer-term studies examining the antibody effects on plaque clearance and cognitive benefit to hold promise for developing disease-modifying anti-Aβ therapeutics for clinical use.

Indoor running temporal variability for different running speeds, treadmill inclinations, and three different estimation strategies.

Inertial measurement units (IMU) constitute a light and cost-effective alternative to gold-standard measurement systems in the assessment of running temporal variables. IMU data collected on 20 runners running at different speeds (80, 90, 100, 110 and 120% of preferred running speed) and treadmill inclination (±2, ±5, and ±8%) were used here to predict the following temporal variables: stride frequency, duty factor, and two indices of running variability such as the detrended fluctuation analysis alpha (DFA-α) and the Higuchi's D (HG-D). Three different estimation methodologies were compared: 1) a gold-standard optoelectronic device (which provided the reference values), 2) IMU placed on the runner's feet, 3) a single IMU on the runner's thorax used in conjunction with a machine learning algorithm with a short 2-second or a long 120-second window as input. A two-way ANOVA was used to test the presence of significant (p<0.05) differences due to the running condition or to the estimation methodology. The findings of this study suggest that using both IMU configurations for estimating stride frequency can be effective and comparable to the gold-standard. Additionally, the results indicate that the use of a single IMU on the thorax with a machine learning algorithm can lead to more accurate estimates of duty factor than the strategy of the IMU on the feet. However, caution should be exercised when using these techniques to measure running variability indices. Estimating DFA-α from a short 2-second time window was possible only in level running but not in downhill running and it could not accurately estimate HG-D across all running conditions. By taking a long 120-second window a machine learning algorithm could improve the accuracy in the estimation of DFA-α in all running conditions. By taking these factors into account, researchers and practitioners can make informed decisions about the use of IMU technology in measuring running biomechanics.

Spatiotemporal walking gait kinematics of semi-arboreal red pandas (Ailurus fulgens).

Semi-arboreal mammals must routinely cope with the differing biomechanical challenges of terrestrial versus arboreal locomotion; however, it is not clear to what extent semi-arboreal mammals adjust footfall patterns when moving on different substrates. We opportunistically filmed quadrupedal locomotion (n = 132 walking strides) of semi-arboreal red pandas (Ailurus fulgens; n = 3) housed at Cleveland Metroparks Zoo and examined the effects of substrate type on spatiotemporal gait kinematic variables using linear mixed models. We further investigated the effects of substrate diameter and orientation on arboreal gait kinematics. Red pandas exclusively used lateral sequence (LS) gaits and most frequently utilized LS lateral couplet gaits across terrestrial and arboreal substrates. Red pandas moved significantly slower (p < 0.001), and controlling for speed, had significantly greater relative stride length (p < 0.001), mean stride duration (p = 0.002), mean duty factor (p < 0.001), and mean number of supporting limbs (p < 0.001) during arboreal locomotion. Arboreal strides on inclined substrates were characterized by significantly faster relative speeds and increased limb phase values compared with those horizontal and declined substrates. These kinematics adjustments help to reduce substrate oscillations thereby promoting stability on potentially precarious arboreal substrates. Red panda limb phase values are similar to those of (primarily terrestrial) Carnivora examined to date. Despite the similarity in footfall patterns during arboreal and terrestrial locomotion, flexibility in other kinematic variables is important for semi-arboreal red pandas that must navigate disparate biomechanical challenges inherent to arboreal versus terrestrial locomotion.

Effect of Copper Percentage in Copper Tungsten Electrode on Ti6Al4V by Electrical Discharge Machining

The aim of this study was to identify the optimal parameters for electrical discharge machining of Ti6Al4V titanium alloy using copper tungsten electrodes with tungsten compositions of 70% and 80%, respectively. The experiment involved varying current, pulse on time, and duty factor were determined using the Taguchi experimental method L-18 orthogonal arrays. The level of importance of each machining parameter on material removal rate (MRR) was determined using analysis of variance (ANOVA), and the optimal machining parameter combination was obtained using the analysis of signal-to-noise (S/N) ratio. The results showed that a Cu30/W70% electrode performed the best in terms of MRR, electrode wear, and surface roughness. The optimal machining conditions for achieving maximum MRR were found to be a current of 30 A, a pulse on time of 50 μs, and a duty factor of 40%.

Duty factor and stride frequency as (potential) load magnitude determinants of slow, female runners’ habitual running pattern

Duty factor and stride frequency as (potential) load magnitude determinants of slow, female runners’ habitual running pattern

Feedforward resonance control for the European X-ray free electron laser high duty cycle upgrade

The High Duty Cycle (HDC) upgrade is a proposed improvement to the existing European X-ray Free Electron Laser (EuXFEL) to extend the pulsed RF duty factor from the actual value of around 1% to more than 5% up to Continuous Wave (CW). To implement this upgrade, the loaded quality factor (QL) of the superconducting cavities will increase by more than one order of magnitude. This will result in shrinking the cavity bandwidth to values as low as a few Hertz. Since the Lorentz Force Detuning (LFD) experienced during the accelerating field buildup is of hundreds of Hertz, the Low-Level RF (LLRF) system has to accurately track and control the cavity resonance frequency to obtain the desired accelerating gradient. Moreover, ponderomotive instabilities have to be suppressed to achieve stability during beam acceleration. Since LFD is a repetitive disturbance in cavity frequency, the correction to its effects can be implemented as a feedforward compensation on the piezoelectric tuners of the cavity. Initial results on the simulation of feedforward resonance control in the HDC regime are discussed in this proceeding.

Small hole fabrication through additively manufactured CuCr1Zr electrode during EDM of a novel Haynes 25 superalloy

Present work proposes an extensive experimental investigation to evaluate the machinability of Haynes 25 work piece with additively manufactured CuCr1Zr (prepared through selective laser melting process), pure copper and graphite electrodes, in view of producing small holes of diameter 3 mm. Prior to machinability investigation, material characterization studies in terms of energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis along with several other mechanical as well as physical properties such as density, microhardness, tensile strength, electric conductivity and thermal conductivity, are carried out for both the electrodes. Outcomes of critical process parameters viz. current (I), voltage (V), pulse on time (Ton), duty factor (τ), and flushing pressure (Fp) are studied on performance measures such as material removal rate (MRR), electrode wear ratio (EWR), specific energy consumption (SEC), surface roughness (Ra), and radial overcut (ROC). The EDMed surface is carefully analysed by a field emission scanning electron microscopy (FESEM) study. It is observed that additively manufactured CuCr1Zr electrode is proficient enough to produce parts with greater accuracy, improved surface finish with least amount specific energy consumption, thus saving cost and time during machining. The ideal level of cutting parameters are identified, validated with confirmative experiment with an average error of 2.79 percentages to produce precise accurate EDMed parts. This work delivers an energy efficient as well as cost effective machining strategy to produce precise and accurate small holes for EDMed applications, thus paving way for productivity of the process.

Parameter optimization in the enhancement of MRR of titanium alloy using newer mixing method in PMEDM process

The addition of powders in electrical discharge machining (EDM) reduces the breakdown strength of the liquid dielectric, thereby enhancing the occurrence of early spark, and aids in machinability. Challenges occur in the sustainability of the powder mixed electrical discharge machining (PMEDM) process in terms of homogeneity of the powder-dielectric mixture and adverse effects of these powders on the impellor of the pump, maintaining the concentration of the powder–dielectric mixture for a wide range of powders at varied size. In this investigation, an attempt is made to address these challenges and limitations in performing PMEDM process by developing a newer mixing method for PMEDM. The Taguchi L18 orthogonal array has been selected to study the material removal rate (MRR) of titanium grade 5 alloy. Gap current, duty factor, pressure of the powder mixed dielectric fluid, type of powder, and concentration of the powders have been considered as the process variables. The results found to be satisfying with increase in MRR. The confirmation experiments indicate considerable increase in MRR. This newer system is capable of performing sustainable manufacturing method irrespective of the nature of the powder and the particle size of the additive powders, that are permissible in the inter-electrode gap as it restricts the size of the powder, added in the PMEDM process.

Spurious Modes in Laterally Excited Bulk Acoustic Resonators (XBARs): Analysis and Suppression

Laterally excited bulk acoustic resonators (XBARs) are plate mode resonators in which one of the higher-order plate modes transforms into the bulk acoustic wave (BAW) due to the very thin plates used in these devices. The propagation of the primary mode is usually accompanied by numerous spurious modes, which deteriorate resonator performances and restrict potential XBARs' applications. This article suggests a combination of different methods for insight into the nature of the spurious modes and their suppression. Analysis of the BAW slowness surface provides optimization of XBARs for single-mode performance in the filter passband and around it. The rigorous simulation of admittance functions in the optimal structures allows for further optimization of electrode thickness and duty factor. Finally, the nature of different plate modes generated in a wide frequency range is clarified via simulation of dispersion curves, which characterize acoustic mode propagation in a thin plate under the periodic metal grating, and visualization of displacements accompanying wave propagation. Application of this analysis to lithium niobate (LN)-based XBARs demonstrated that in LN cuts with Euler angles (0°, 4°-15°, 90°) and plate thickness dependent on orientation and varying between 0.05 and 0.1 wavelengths, the spurious-free response could be achieved. Due to tangential velocities of 18-37 km/s combined with the coupling of 15%-17% and feasible duty factor a/p = 0.5, the found XBAR structures can be applied in high-performance 3-6 GHz filters.

Comparison of different machine learning models to enhance sacral acceleration-based estimations of running stride temporal variables and peak vertical ground reaction force

ABSTRACT Machine learning (ML) was used to predict contact () and flight () time, duty factor (DF) and peak vertical force () from IMU-based estimations. One hundred runners ran on an instrumented treadmill (9–13 km/h) while wearing a sacral-mounted IMU. Linear regression (LR), support vector regression and two-layer neural-network were trained (80 participants) using IMU-based estimations, running speed, stride frequency and body mass. Predictions (remaining 20 participants) were compared to gold standard (kinetic data collected using the force plate) by calculating the mean absolute percentage error (MAPE). MAPEs of did not significantly differ among its estimation and predictions (P = 0.37), while prediction MAPEs for , and DF were significantly smaller than corresponding estimation MAPEs (P ≤ 0.003). There were no significant differences among prediction MAPEs obtained from the three ML models (P ≥ 0.80). Errors of the ML models were equal to or smaller than (≤32%) the smallest real difference for the four variables, while errors of the estimations were not (15–45%), indicating that ML models were sufficiently accurate to detect a clinically important difference. The simplest ML model (LR) should be used to improve the accuracy of the IMU-based estimations. These improvements may be beneficial when monitoring running-related injury risk factors in real-world settings.

Investigation of tool wear rate during micro-electrochemical spark machining process

Micro-electrochemical spark machining (micro-ECSM) process exhibits good potential to process any materials with high dimensional accuracy and surface quality. However, the tool erosion (due to sparking) in different directions affects the accuracy of the finished features. Tungsten carbide (WC) material is widely used as a tool material to minimize dimensional inaccuracy of the machined part. Tungsten is a potential alternative tool material for this process, having melting point higher than WC. Due to the high melting point, the radial and axial erosion may be reduced significantly. The in-depth study on tungsten tool erosion (wear) behaviour has not been studied widely. In this work, the influence of different input machining parameters on tool erosion behaviour has been explored. The influence of voltage, duty factor, pulse frequency, electrolyte type, their concentrations, and tool immersion length in the electrolyte was considered for the analysis purpose. The results reveal that voltage is the most influencing parameter for tool erosion which mainly occurs at the bottom edge, whereas electrolyte level is the least influencing parameter. The tool weight loss is increased to 153% by changing voltage from 50 V to 60 V whereas axial length loss is 146 µm at 60 V is observed. Further, the micro hole is fabricated at machining parameter voltage: 50 V, duty factor: 40%, frequency: 6 kHz, NaOH electrolyte of concentration 2 M, and 2 mm electrolyte level. The wall surface of the hole shows an average surface roughness of 4.31 µm having the average recast layer thickness and HAZ of 31 µm and 56 µm, respectively, at the edge of the hole.

Biomechanical adaptations during exhaustive runs at 90 to 120% of peak aerobic speed

The aim of this study was to examine how running biomechanics (spatiotemporal and kinetic variables) adapt with exhaustion during treadmill runs at 90, 100, 110, and 120% of the peak aerobic speed (PS) of a maximal incremental aerobic test. Thirteen male runners performed a maximal incremental aerobic test on an instrumented treadmill to determine their PS. Biomechanical variables were evaluated at the start, mid, and end of each run until volitional exhaustion. The change of running biomechanics with fatigue was similar among the four tested speeds. Duty factor and contact and propulsion times increased with exhaustion (P ≤ 0.004; F ≥ 10.32) while flight time decreased (P = 0.02; F = 6.67) and stride frequency stayed unchanged (P = 0.97; F = 0.00). A decrease in vertical and propulsive peak forces were obtained with exhaustion (P ≤ 0.002; F ≥ 11.52). There was no change in the impact peak with exhaustion (P = 0.41; F = 1.05). For runners showing impact peaks, the number of impact peaks increased (P ≤ 0.04; {upchi }^{2} ≥ 6.40) together with the vertical loading rate (P = 0.005; F = 9.61). No changes in total, external, and internal positive mechanical work was reported with exhaustion (P ≥ 0.12; F ≤ 2.32). Results suggest a tendency towards a “smoother” vertical and horizontal running pattern with exhaustion. A smoother running pattern refers to the development of protective adjustments, leading to a reduction of the load applied to the musculoskeletal system at each running step. This transition seemed continuous between the start and end of the running trials and could be adopted by the runners to decrease the muscle force level during the propulsion phase. Despite these changes with exhaustion, there were no changes in either gesture speed (no alteration of stride frequency) or positive mechanical work, advocating that runners unconsciously organize themselves to maintain a constant whole-body mechanical work output.

Diagonal-couplet gaits on discontinuous supports in Japanese macaques and implications for the adaptive significance of the diagonal-sequence, diagonal-couplet gait of primates.

Diagonal-sequence, diagonal-couplet (DSDC) gaits have been proposed as an adaptation to travel on discontinuously arranged arboreal branches. Only a few studies have examined primate gait adjustment to support discontinuity. We analyzed the gaits of Japanese macaques walking on the "ground" and two discontinuous conditions, "circle" and "point," to better understand the advantages of DSDC gaits on discontinuous supports. Seventy-eight vertical posts, each with a circular upper surface, were arranged in four rows at a spacing of 200 mm. The diameter of the circular upper surface was 150 mm ("circle condition") or 50 mm ("point condition"). We calculated the limb phase, duty factor, and time interval from hindlimb touchdown to ipsilateral forelimb liftoff. The supports the fore- and hindlimbs landed on during walking were identified in the circle and point condition. The macaques predominantly used DSDC gaits in the ground and circle conditions and lateral-sequence, diagonal-couplet (LSDC) gaits in the point condition. The macaques usually placed their hindlimbs on the same supports as their ipsilateral forelimbs during the gait cycle. Japanese macaques overlapped the ipsilateral fore- and hindlimb stance phase in all DSDC and some LSDC gaits to proximate the ipsilateral limbs on the discontinuous support, allowing the forelimb to guide the hindlimb placement to the support. The overlap duration of the ipsilateral limb stance phases may be extended by DSDC gaits longer than by LSDC gaits, allowing for a direct pass of the support being held by the prehensile hand to the prehensile foot.

Effects of the speed on the webbed foot kinematics of mallard (Anas platyrhynchos).

In this study, the effect of the speed on the webbed foot locomotion of the mallard was analyzed based on a considerable number of reliable indoor test data. Four adult male mallards were selected for analysis, and the locomotion speed of the mallard was controlled using the treadmill at an accurate and adjustable speed. The locomotion pattern of the webbed foot of the mallard at different speeds was recorded using a high-speed camera. The changes in the position and conformation of the webbed foot during locomotion on a treadmill were tracked and analyzed using Simi-Motion kinematics software. The results indicated that the stride length of the mallard increased, and the stance phase duration was shortened with the increase of the speed, whereas the swing phase duration did not vary significantly. The duty factor decreased with the increase of the mallard speed but not drop below to 0.5, because the mallards flew with their wings, or moved backward relative to the treadmill with the further increase of the speed. Using the energy method to further distinguish gait, and through the percentage of congruity analysis, it was found that between 0.73 and 0.93 m/s, the gait experienced a transition from walking to grounded running, with no significant changes in spatiotemporal parameters. At speeds between 0.93 and 1.6 m/s, mallards adopt a grounded running gait. The instantaneous changes of the tarsometatarso-phalangeal joint (TMTPJ) angle and the intertarsal joint (ITJ) angle at touch-down, mid-stance and lift-off concomitant with the change of the speed were examined with the TMTPJ and ITJ angle as the research objects. Moreover, the continuous changes of the joint angles were examined in a complete stride cycle. The result indicated that the increase of the speed will also make the TMTPJ and ITJ angle change ahead of time in a stride cycle, proving the shortened stance phase duration. The ITJ angle changed much more than the TMTPJ. Thus, the above result reveals that the mallard primarily responds with the increase of the speed by adjusting the ITJ, instead of the TMTPJ. The vertical displacement of the toe joint points and the toe joint angle was studied (α joint angle is between the second toe and the third toe; β joint angle is between the third toe and the fourth toe) with a complete stride cycle as the research object. The distal phalanxes of the second, third and fourth toes first contacted the ground, and the proximal phalanx touched the ground in turn during the early stance phase duration of the mallard, as indicated by the result of this study. However, the toes got off the ground in turn from the proximal phalanxes when the mallard foot got off the ground. With the decrease of the interphalangeal α and β joint angles, the foot web tended to be close and rapidly recovered before the next touch-down. The above result reveals that the webbed foot of the mallard is a coupling system that plays a role in the adjustment of speed.

Duty factor: A key biomechanical injury risk factor in leisure-time runners

Breaking the capacity barrier in intercalation-type anode materials for lithium-ion batteries while preserving other essential electrochemical properties remains a significant challenge. Here, using perovskite SrVO3 as a model, we demonstrate the feasibility of employing defect engineering to provide extra active sites for electrochemical reactions. Defective SrxVO3-δ samples with a unique amorphous-crystalline dual-phase structure are successfully prepared by regulating the nonstoichiometric Sr/V ratio and using a non-equilibrium solution combustion strategy to alleviate nucleation. The dual-phase SrxVO3-δ electrodes, which take advantage of both the high defect concentration advantage of amorphous and the high electrical/ionic conductivity of crystalline, give a high specific capacity of 508 mAh/g at a safe potential of 1.0 V vs. Li/Li+, showing a 40% increase over SrVO3 electrodes and outperforming most state-of-the-art intercalation-based anodes. In addition, when coupling with LiFePO4 cathode, the SrxVO3-δ electrodes can operate over 10,000 cycles with 91% capacity retention, overcoming the limited structural stability exhibited in typical defective electrodes. The study demonstrates the viability of modulating the crystallinity in intercalation-based anodes to enhance electrochemical performance and paves the way for the advancement of Li-ion battery technology.

Technical note: Delivery benefit and dosimetric implication of synchrotron-based proton pencil beam scanning using continuous scanning mode.

Discrete spot scanning (DSS) is the commonly used method for proton pencil beam scanning (PBS). There is lack of data on the dose-driven continuous scanning (DDCS). To investigate delivery benefits and dosimetric implications of DDCS versus DSS for PBS systems. The irradiation duty factor, beam delivery time (BDT), and dose deviation were simulated for eight treatment plans in prostate, head and neck, liver, and lung, with both conventional fractionation and hypofractionation schemes. DDCS results were compared with those of DSS. The DDCS irradiation duty factor (range, 11%-41%) was appreciably improved compared to DSS delivery (range, 4%-14%), within which, hypofractionation schemes had greater improvement than conventional fractionation. With decreasing stop ratio constraints, the DDCS BDT reduction was greater, but dose deviation also increased. With stop ratio constraints of 2, 1, 0.5, and 0, DDCS BDT reduction reached to 6%, 10%, 12%, and 15%, respectively, and dose deviation reached to 0.6%, 1.7%, 3.0%, and 5.2% root mean square error in PTV DVH, respectively. The 3%/2-mm gamma passing rate was greater than 99% with stop ratio constraints of 2 and 1, and greater than 95% with a stop ratio of 0.5. When the stop ratio constraint was removed, five of the eight treatment plans had a 3%/2-mm gamma passing rate greater than 95%, and the other three plans had a 3%/2-mm gamma passing rate between 90% and 95%. The irradiation duty factor was considerably improved with DDCS. Smaller stop ratio constraints led to shorter BDTs, but with the cost of larger dose deviations. Our finding suggested that a stop ratio of 1 constraint seems to yield acceptable DDCS dose deviation.