Step Angle Research Articles

Electroosmotic Flow-Driven DNA-CNT Nanomotor via Tunable Surface-Charged Nanopore Array.

Nanomotors are usually designed to work in liquid media and carry cargo; they exhibit excellent potential for biosensing and disease treatment applications due to their small size. Graphene and carbon nanotubes (CNTs) are crucial components of rotary nanomotors because of excellent mechanical properties and adaptability to the human body. Herein, we introduce a DNA-CNT-based nanomotor that achieves its rotational control through an array of nanopores with tunable surface charges. The findings demonstrate that by adjusting the surface charge density of the nanopores and the direction of electric field, a DNA strand can be sequentially captured by the nanopores, thereby rotating the connected CNT. The transition from a four-nanopore array to a six-nanopore array reveals that reducing the step angle to 60° significantly enhances the rotational stability of the nanomotor and reduces random fluctuations caused by Brownian motion. This method improves the control stability of the nanomotor, providing robust support for future applications in nanoscale manipulation.

Study on vehicle state and tire–road friction coefficient estimation based on maximum correntropy generalized high-degree cubature Kalman filter

To cope with the challenges of inadequate precision and weak robustness of tire–road friction coefficient (TRFC) and vehicle state estimation under mixed Gaussian noise circumstances, this research puts forward a method combining maximum correntropy criterion (MCC) and generalized high-degree cubature Kalman filter (GHCKF). A coupled lateral and longitudinal vehicle model and the Dugoff tire model are established. The vehicle mass is estimated using the recursive least squares approach based on a forgetting factor (FFRLS). Low-cost onboard sensors are utilized to design observers for vehicle state and TRFC. The observers’ effectiveness is tested by Carsim/Simulink co-simulation tests under the conditions of sine steering input and steering wheel angle step input. The research results indicate that in handling mixed Gaussian noise environments, maximum correntropy generalized high-degree cubature Kalman filter (MCGHCKF) method outperforms maximum correntropy cubature Kalman filter (MCCKF), GHCKF, and cubature Kalman filter (CKF) methods concerning robustness and estimation accuracy, providing stable and reliable support for systems of vehicle active safety control.

Design, development and multi-scenario application of portable multifunctional test master based on μM-PMU: The case study of Lingang new City Grid, Shanghai

With the large-scale access of new energy generation and electric vehicle charging piles to the grids, power generation and loads are characterized by random fluctuations and intermittency, which affect the stable operation of the distribution network. μM-PMU is capable of realizing the dynamic process monitoring of the grids. In order to solve the function and performance testing problems of multiple application scenarios of μM-PMU, this thesis develops a portable master station based on synchronous phasor measurement system to realize zero drift, voltage amplitude measurement accuracy, voltage phase angle accuracy, current amplitude measurement accuracy, current phase angle measurement accuracy, frequency measurement accuracy, voltage amplitude change with frequency accuracy, and voltage phase angle change with frequency accuracy, Accuracy of current amplitude with frequency change, accuracy of current phase angle with frequency change, active power accuracy, reactive power accuracy, amplitude step response, phase angle step response, frequency step response, a total of 15 test items. It can automatically calculate test results and generate test reports according to different equipment models, reducing the mistakes and calculation errors that may be caused by manually recording test data and improving the accuracy of test results and calculation precision.

Transport properties of YBCO step edge Josephson junction with different step angles

Transport properties of YBCO step edge Josephson junction with different step angles

Enhancing hoof health and locomotion in crossbred dairy cows: impact of recycled manure solids bedding on lameness incidence and gait kinematics.

Recycled manure solids has emerged as a promising alternative for animal bedding, owing to its economic feasibility, ready availability on farms, and soft, non-abrasive nature. This research aimed to assess the impact of recycled manure solids (RMS) bedding, combined with a conditioner containing 7.5% lime and 6% sodium hydrosulphate, on dairy cow welfare and gait kinematics over three months. Hock and knee injury scores, lameness incidence, and gait kinematic parameters were evaluated for animals housed on cement flooring (Control), RMS bedding (Treatment I), and conditioner-added RMS bedding (Treatment II) on days 0, 45, and 90 of the experiment with six crossbred cows in each group. The results revealed a significant reduction (p < 0.05) in lameness scores (5-point scale) for animals in both the RMS and conditioner-added RMS groups, with scores of 1.09 ± 0.05 and 1.04 ± 0.03, respectively, compared to those on cement floors. Moreover, a noteworthy decrease (p < 0.05) in knee and hock injury scores (4-point scale) was observed in the RMS groups, indicating a potentially positive impact on joint health. Gait kinematic analysis demonstrated that animals in the RMS (1.03 ± 0.04m/s) and conditioner-added RMS (1.02 ± 0.06m/s) groups exhibited higher walking speeds and increased step angles (158.59 ± 4.82° and 149.58 ± 3.85°) compared to their cement-floor counterparts. No significant changes (p > 0.05) were observed in stride length, step asymmetry, step length, and step width. The study concluded that the conditioner incorporated recycled manure solids resulting in a substantial decrease in lameness incidence and a reduction in hock and knee injuries among dairy cows. Additionally, the improved gait kinematics observed in non-lame animals suggest that this bedding combination positively influences overall animal well-being. These findings underscore the potential of sustainable bedding practices to enhance both physical health and locomotor behaviour in dairy cattle.

Buoyancy-driven micropolar ternary hybrid nano-suspension within an oblique incinerator-shaped chamber: Thermal and second law analyses

Since performance of thermal systems may depend on fluids’ thermal conductivities being utilized as coolants, improvement of thermal efficiencies of fluids having micro-structures and involving ternary hybrid nanomaterials may be highly valued. In fact, microrotation of ternary hybrid nanofluids (THNFs) in oblique incinerator-shaped chamber may find applications in industrial processes involving polymeric solutions and lubricants where they help in reduction of drag forces and act as better cooling agent. In view of this, the present study carries out thermal and second law dissection of micropolar THNF within an oblique incinerator-shaped chamber heated from bottom emplacing a roundish heater under a fixed heat flux. The THNF comprises of Al2O3, CNT and graphene as nanoparticles. The study reveals that streamlines and isotherms undergo prominent change due to inclination of the chamber. When Raleigh number and diameter of heater amplify streamlines, microrotations, and entropy generation intensify while average Bejan number whittles down. Average heat transfer rate ameliorates by 4.54 % and 2.17 % when total volume fraction augments from 1.5 % to 3 % and 3 %–4.5 %, respectively. Heat transfer rate reduces by 1.23 %, 0.48 %, 3.33 %, 5.24 %, 2.07 %, and 1.66 % when inclination angle increases from 0° to 90° with inclination angle step 15°.

Impact of step width on trunk motion and gait adaptation in elderly women with knee osteoarthritis.

Step width during walking can provide important information about aging and pathology. Although knee osteoarthritis (OA) is a common disease in elderly women, little is known about how different step widths influence gait parameters in patients with knee OA. To address this, we investigated the differences between narrower and wider step width on the center of mass (CoM) and gait biomechanics of elderly women with knee OA. Gait and CoM data were measured using a three-dimensional motion capture system and anthropometric data were acquired via standing full-limb radiography. Thirty elderly women with knee OA were divided into two groups depending on the average step width value (0.16 m). Specifically, the narrower step width group included those with a below average step width (n= 15) and the wider step width group included those with an above average step width (n= 15). The differences between the two groups were analyzed using an independentt-test. Walking speed, step length, knee and ankle sagittal excursion, and medial-lateral CoM range were significantly greater in the narrower group. In contrast, the medial-lateral CoM velocity, medial-lateral ground reaction force (GRF), and foot progression angle were significantly higher in wider group. The external knee adduction moment, vertical GRF, and vertical CoM did not differ between the groups. Our data indicate that step width in women with knee OA is associated with trunk motion and gait patterns. People with a narrower step might improve their gait function by increasing trunk frontal control to maintain gait stability. In contrast, in those with a wider step, greater toe out angle and shorter step length might be a compensatory adaptation to reduce knee loading.

An Experimental Investigation Of µUAV Rotor Wingtip Vortices Through High Spatial Resolution PIV

The interest for µ UAVs platforms with VTOL capabilities dramatically rose over the last decade due to the fast-paced advancements in electronics and control. However, the vortical structures shedded from the rotary wings -and their interaction-, which are responsible for high power usage and high noise level emissions, are yet to be fully understood. In this work, an experimental PIV campaign was conducted on a commercially available propeller with a 230mm diameter. The operating angular velocity was chosen to be 5750RPM, producing a chord Reynolds number of about Re_{c,75%} ≃ 11000, generating 3.42N of thrust while requiring 55W of power. The resolution of the PIV setup was able to reliably fit 8 measurement points in the vortex core when using narrowest field-of-view (FOV), while the widest FOV comprises a measurement area of about 0.5D×0.57D. Time averaged as well as phase averaged measurements were performed. The evolution and interaction of the wingtip vortices and shear layers shedded in the flow field is captured with an azimuthal angle step increment of ∆Ψ = 5º. The thrust produced by the multirotor configuration was indeed found to be approximately 5% lower than the one produced by the isolated propeller in hovering conditions. Additionally, the PIV setup successfully met the target spatial accuracy requirements: induced velocities are accurately captured in every stage of the wingtip vortex evolution.

Statistical image reconstruction with beam-hardening compensation for X-ray CT by a calibration step (2DIterBH).

The beam-hardening effect due to the polychromatic nature of the X-ray spectra results in two main artifacts in CT images: cupping in homogeneous areas and dark bands between dense parts in heterogeneous samples. Post-processing methods have been proposed in the literature to compensate for these artifacts, but these methods may introduce additional noise in low-dose acquisitions. Iterative methods are an alternative to compensate noise and beam-hardening artifacts simultaneously. However, they usually rely on the knowledge of the spectrum or the selection of empirical parameters. We propose an iterative reconstruction method with beam hardening compensation for small animal scanners that is robust against low-dose acquisitions and that does not require knowledge of the spectrum, overcoming the limitations of current beam-hardening correction algorithms. The proposed method includes an empirical characterization of the beam-hardening function based on a simple phantom in a polychromatic statistical reconstruction method. Evaluation was carried out on simulated data with different noise levels and step angles and on limited-view rodent data acquired with the ARGUS/CT system. Results in small animal studies showed a proper correction of the beam-hardening artifacts in the whole sample, independently of the quantity of bone present on each slice. The proposed approach also reduced noise in the low-dose acquisitions and reduced streaks in the limited-view acquisitions. Using an empirical model for the beam-hardening effect, obtained through calibration, in an iterative reconstruction method enables a robust correction of beam-hardening artifacts in low-dose small animal studies independently of the bone distribution.

Anisotropic Mechanical Properties and Fracture Mechanism of Transversely Isotropic Rocks under Uniaxial Cyclic Loading

Transversely isotropic rocks, which are special anisotropic materials, are widely encountered in civil, mining, petroleum, geothermal, and radioactive waste-disposal engineering. Rock is frequently subject to cyclic loads resulting from natural and human-caused events. However, to date, the fracture mechanism of transversely isotropic rocks under cyclic loading remains poorly understood. To address this gap, uniaxial monotonic-loading and cyclic-loading tests were performed on slate specimens by the MTS815 system, during which acoustic emission (AE) signals inside the rock were monitored, and finally the fracture surfaces of the tested rock were scanned by scanning electron microscopy (SEM). Through these tests, the anisotropic mechanical properties, damage evolution, AE characteristics and fracture pattern of slate as a transversely isotropic rock were studied. The results show that the peak strength of specimens varies with the loading–foliation angle under monotonic and cyclic loading, following a U-shaped trend. The deformation modulus during unloading is more capable of characterizing the damage inside the specimen than that during loading. By defining the damage degree based on dissipation energy, it is found that the damage variable is influenced by the loading–foliation angle and the cyclic stress step. The AE characteristics of specimens exhibit significant anisotropy, closely correlated to the loading condition and loading–foliation angle. Regardless of cyclic stress step, the AE counts of specimens with a loading–foliation angle of 0° are mainly distributed near the peak region, whereas those of specimens with other loading–foliation angles occur primarily in the early stage of each cyclic loading. Finally, it is revealed that the fracture mechanism of slate specimens is determined by the loading–foliation angle, loading condition, and cyclic stress step.

Tuning the Actuator Line Method to Properly Modelling Tip Effects in Finite-Length Blades

The Actuator Line Method (ALM) is gaining popularity in wind turbine simulations, as it can better handle some of the challenging operating conditions experienced by modern machines, such as highly turbulent inflows, severe aero-elastic forcing, and complex rotor-to-rotor interactions. However, it still falls behind other medium-fidelity methods such as the Lifting Line Free Vortex Wake (LLFVW) when it comes to resolving tip vortices and their effect on the blade spanwise load profile. The reason for such behavior is still unclear. A recent study suggested that this issue can be solved by reducing the scale of the angle of attack (α) sampling and force insertion towards the tip, without the need of additional corrections. This study builds on these findings to further investigate how the ALM base formulation - in terms of α sampling and force insertion - can be tuned to properly describe tip effects. An in-house ALM tool was employed to simulate a finite, constant-chord, NACA0018 wing, for which high-fidelity blade-resolved CFD (BR-CFD) data are available as benchmark. In the first part of the work, different strategies are outlined, including a novel approach for the de-coupling of the angle of attack sampling step from the force projection one, here called DE-coupled LineAverage (DELA). Their accuracy and sensitivity to ALM numerical settings are assessed at a fixed wing pitch angle of 6°. The analysis is then extended to a wider range of blade pitch angles, benchmarking the new ALM formulation against BR-CFD, ALM with the Dağ and Sørensen correction, and LLFVW in terms of blade loads, tip vortex structure, and computational effort.

Design of four-wheel steering system based on automotive electronic control technology

Abstract With the rapid development of the automobile industry, people’s requirements for automobile handling performance and driving safety are getting higher and higher. As an important automobile power system, four-wheel steering technology can improve the maneuverability, stability, and safety of vehicles by controlling the steering angles of front and rear wheels. Therefore, the design and research of the four-wheel steering system has become one of the hotspots in the field of automotive engineering. In this paper, a two-degree-of-freedom dynamics model is established, and based on the PID control strategy of joint feedback of center-of-mass lateral deflection and traverse angular velocity, the vehicle model of a four-wheeled steering vehicle is constructed by using TruckSim, and the minimum turning radius test, serpentine test, and steering wheel angle step test project are carried out. The results show that compared with the two-wheel steering vehicle, the minimum turning diameter of the four-wheel steering vehicle is reduced by 1/3, which effectively improves the maneuverability at low speeds as well as the safety and stability at high speeds, and has better transient response.

Ubiquitous Gait Analysis through Footstep-Induced Floor Vibrations.

Quantitative analysis of human gait is critical for the early discovery, progressive tracking, and rehabilitation of neurological and musculoskeletal disorders, such as Parkinson's disease, stroke, and cerebral palsy. Gait analysis typically involves estimating gait characteristics, such as spatiotemporal gait parameters and gait health indicators (e.g., step time, length, symmetry, and balance). Traditional methods of gait analysis involve the use of cameras, wearables, and force plates but are limited in operational requirements when applied in daily life, such as direct line-of-sight, carrying devices, and dense deployment. This paper introduces a novel approach for gait analysis by passively sensing floor vibrations generated by human footsteps using vibration sensors mounted on the floor surface. Our approach is low-cost, non-intrusive, and perceived as privacy-friendly, making it suitable for continuous gait health monitoring in daily life. Our algorithm estimates various gait parameters that are used as standard metrics in medical practices, including temporal parameters (step time, stride time, stance time, swing time, double-support time, and single-support time), spatial parameters (step length, width, angle, and stride length), and extracts gait health indicators (cadence/walking speed, left-right symmetry, gait balance, and initial contact types). The main challenge we addressed in this paper is the effect of different floor types on the resultant vibrations. We develop floor-adaptive algorithms to extract features that are generalizable to various practical settings, including homes, hospitals, and eldercare facilities. We evaluate our approach through real-world walking experiments with 20 adults with 12,231 labeled gait cycles across concrete and wooden floors. Our results show 90.5% (RMSE 0.08s), 71.3% (RMSE 0.38m), and 92.3% (RMSPE 7.7%) accuracy in estimating temporal, spatial parameters, and gait health indicators, respectively.

Analysis of the Relationship between Step Angle and Step Rate during Running: Implication for Rehabilitation

In running, step rate and step angle are important, but the relationship between the two parameters is not clear in the literature. This study aimed to investigate the effect of step rate manipulation on step angle in running. A group of twenty healthy recreational runners aged between 30 and 59 years who regularly run 15–90 km per week were recruited. Kinematic data were recorded using a motion capture system while running on a treadmill. Participants maintained a self-selected speed and then altered their step rate using a metronome and completed three thirty-second trials at the preferred step rate, 10% above the preferred step rate and 10% below the preferred step rate. The results showed that the step angle is not significantly correlated with the step rate and kept at roughly 37 degrees at the preferred step rate and 10% lower than the preferred step rate but increased to 42 deg when the step rate increased to 10% of the preferred step rate. The step angles were not significantly different between the male and female or between sides. This finding provides an understanding of the association of step rate re-training on swing phase parameters.

Optimizing Algorithm for Existing Fiber-Optic Displacement Sensor Performance.

This paper describes the optimal design of a miniature fiber-optic linear displacement sensor. It is characterized by its ability to measure displacements along a millimetric range with sub-micrometric resolution. The sensor consists of a triangular reflective grating and two fiber-optic probes. The measurement principle of the sensor is presented. The design of the sensor's triangular grating has been geometrically optimized by considering the step angle of the grating to enhance the sensor's resolution. The optimization method revealed a global optimum at which the highest resolution is obtained.

The learning of sprint hurdles: A comparative study on increasing contextual interference and blocked practice schedules.

The contextual interference (CI) approach has proposed that a random order of practice for motor skills is superior in facilitating learning compared to a blocked arrangement of practice trials. Two groups of physical education students learned sprint hurdles, employing either an increasing CI practice schedule (n = 23) or a blocked practice schedule (n = 23). In both the practice schedules, the same exercises were used in a different trial order during each learning session. Eleven practice sessions were conducted over a period of six weeks, with two days of practice per week. Ten and 40 days after the acquisition phase, a retention and transfer test were conducted. The results showed no differences between the two practice schedules during the retention tests. However, students practicing with an increasing CI arrangement performed better on the delayed transfer test compared to students which practiced with a blocked schedule. Specifically, the increasing CI group more effectively (p < 0.05) cleared the hurdles due to a lower take-off step angle and longer step length than the blocked practice group. Although utilizing an increase in CI during the learning phase of sprint hurdling produced more persistent learning effects relative to a traditional blocked practice schedule for adult novice learners, further research is warranted to explore the CI effect across a broader range of sport skills.

Optimization of geometrical parameters of the heat receiver of a solar air heating collector

The article presents the optimization of the radiant surface of the solar air heating collector (SAH). As a radiation-receiving surface of the SAH, a surface is used, which is a system of metal drainage shavings and a V-shaped surface. Based on the study of the heat transfer process, an effective scheme of heat removal from the radiation-receiving surface of the SAH is presented. When optimizing the radiation-sensing surface of the SAH, the process of radiation-sensing of the surface, which depends on the geometric shape of the chips, is taken as the target function of the maximum. A formula is proposed for calculating the determination of the transmitted amount of the radiant flux of the sun to the unit of the frontal surface through the shape of the metal shavings from the value of the opening step angle in different thicknesses of the metal shavings. It has been confirmed that the solar radiant flux passing to the unit of the frontal surface through the metal chip shape reaches its maximum value in the following cases: when the chips are 0,002 m thick, they have an optimal angle φ = 58°, the transmitted energy of the radiant flux through the chip shape is E = 31%; with a chip thickness of 0,0005 m, the optimal angle is φ = 42°, the transmitted energy of the radiant flux through the chip shape is E = 41%; with a thickness of 0,001 m, the optimal angle is φ = 50°, the transmitted energy of the radiant flux through the chip shape is.

Landing control of a returned spacecraft under conditions of uncertainty

The nonlinear model of a spacecraft requires high robustness, and the classical control method, as one of the earliest developed control methods, has simple algorithms and high robustness. A control system structure that ensures retention attack angle and overload by combining fuzzy control with classical control for adaptive optimization and adjustment of control parameters and tracking of the attack angle step signals is proposed. The simulation results show that the performance of the improved system is better than that of the original system. Improved algorithms are used to simulate the attack angle and overload retention sections, also simulated aerodynamic uncertainties is carried out. The results show that the developed control law meets the requirements of a certain level of robustness. Keywords aerospace vehicles, position control, adaptive fuzzy control, PID adjusting, uncertainty

Numerical study on the kerosene deflection characteristics and regulation methods of supersonic combustor equipped with a 75° swept strut

To promote the application of the swept strut in the supersonic combustor to solve the problem of thermal protection and resistance reduction of the strut injector at high flight Mach number, the kerosene mixing characteristics in the combustor equipped with a swept strut were studied by numerical simulation under the condition of Ma = 2.8, Pt = 1.68 MPa and Tt = 1680K. The results show that the kerosene deflection will occur in the combustor, and the kerosene is mainly enriched in the boundary layer of the combustor wall, which makes the kerosene's local mixing performance poor and the combustion efficiency low. Further analysis indicates that the kerosene deflection characteristics are mainly caused by the transport effect of the counter-rotating vortex pair (CVP) and the pressure distribution characteristics of the strut surface. To improve the phenomenon of kerosene enrichment and the uniformity of kerosene distribution, the regulation of kerosene deflection characteristics was studied from strut configuration design and kerosene distribution of strut injection orifices. The results show that the uniformity of the kerosene distribution can be improved by selecting the appropriate strut height, the trailing-edge swept angle of the strut and the step angle of the strut. The kerosene mixing efficiency and the uniformity of kerosene distribution can be improved by grouping the kerosene injection orifices of the strut and assigning the appropriate equivalence ratio to each group of injection orifices.

Drag reduction using riblets downstream of a high Reynolds number inclined forward step flow

Micro-riblet is an efficient passive method for controlling turbulent boundary layers, with the potential to reduce frictional drag. In various applications within the transportation industry, flow separation is a prevalent flow phenomenon. However, the precise drag reduction performance of riblets in the presence of flow separation remains unclear. To address this, an inclined forward step model is proposed to investigate the interaction between riblet and upstream flow separation. The large eddy simulation (LES) method is applied to simulate the flow over geometries with different step angles and riblet positions. The results show riblets still reduce wall frictional resistance when subjected to the upstream flow separation. Remarkably, as the angle of the step increases from 0° to 30°, the drag reduction experiences an increment from 9.5% to 12.6%. From a turbulence statistics standpoint, riblets act to suppress the Reynold stress in the near-wall region and dampen ejection motions, thus weakening momentum exchange. Quadrant analysis reveals that with the augmentation of flow separation, the Q2 motion within the flow field intensifies, subsequently enhancing the riblet-induced drag reduction. Moreover, the position of the riblets has a significant impact on the pressure drag. Riblets close to the point of separation enhance flow separation, altering the surface pressure distribution and thus increasing the resistance. The results reveal that when the riblets are positioned approximately 160 riblet heights away from the step, their effect on the upstream flow separation becomes negligible. The precise performance of riblets under complex flow conditions is important for their practical engineering application.