Force Characteristics Research Articles

The association between students’ confidence and ability to modulate spinal manipulation force–time characteristics of specific target forces: a cross-sectional study

Abstract Background Spinal manipulative therapy (SMT) is a guideline-recommended care for musculoskeletal pain taught in various undergraduate programs. Visual feedback through force-sensing tables can improve modulation of SMT force–time characteristics and, potentially, students’ confidence, both factors important for clinical competence and patient outcomes. However, it is unclear if a link exists between students’ confidence and ability in SMT force–time modulation. We aim to investigate this relationship and whether it was moderated by experience. Methods This cross-sectional study recruited first- to third-year Canadian Memorial Chiropractic College students. Participants provided information about their confidence in performing SMT using different impulse forces of 200N, 400N, and 800N with a pre-established pre-load and a time-to-peak force < 150ms. SMT impulse forces of 200N, 400N, and 800N were targeted on a Human Analogue Mannequin positioned prone on a force-sensing table. We described the confidence levels and SMT force–time characteristics and assessed their association using linear mixed models. We re-ran the models interacting with SMT experience. The order of the three SMT impulse forces was randomly performed. Participants and outcome assessors were blinded to force–time characteristics recordings. Results One-hundred-and-forty-nine participants provided usable data. Participants were confident in delivering 200N and 400N impulse forces. However, confidence decreased for 800N forces. Accordingly, participants performed impulse forces close to the 200N and 400N but had difficulty accurately modulating to 800N forces. A positive association was found between confidence and the ability to modulate their force–time characteristics, especially keeping the same pre-load force, keeping the time to peak force < 150ms, and providing the 800N impulse force. This association was not moderated by experience. Conclusions Students were more confident in their abilities to perform lower SMT forces but lacked confidence in their abilities to perform higher (800N) forces. This aligned with their skills, as many struggled to apply 800N force. However, students who had higher confidence levels generally performed better overall. There was substantial variability in SMT force–time characteristics, which may have implications for adverse events and patient satisfaction. Some of this variability could be attributed to students’ confidence. Thus, further investigations are necessary in undergraduate settings to implement and optimize these findings. Registration https://osf.io/6f7d5

The Anti/Deicing Performance of the Low Interfacial Toughness Coating Is Enhanced: Induced Ice Crack Generation and Its Extension.

The low interfacial toughness of the material surface is important for crack initiation and expansion of the ice layer as it remains an effective method for large-scale deicing. However, there are challenges, such as a large critical icing size and incomplete shedding of the ice layer. Adjusting the interfacial forces to make the ice more prone to cracking, expanding, and shedding is advantageous in addressing the problem of anti-icing failure in materials with low interfacial toughness. Therefore, we propose a deicing strategy that combines porous PDMS (polydimethylsiloxane) coatings with low interfacial toughness and piezoelectric vibration. A series of hydrophobic porous PDMS coatings with different porosities were prepared on the surface of an aluminum alloy substrate through curing and phase separation. The elastic modulus of the coatings decreased from 1465 to 509 kPa as the coating porosity increased, revealing the mechanism behind the improvement in mechanical properties. The key to promoting ice fracture on porous PDMS coatings lies in the synergistic effect of the out-of-plane shear stress and microcracks at the solid-ice interface. This work focuses on exploring the characteristics of interfacial forces by combining the intrinsic mechanical properties of coatings with external forces, providing new insights for designing low interfacial toughness anti-icing materials.

Multi‐operating characteristic analysis and loss optimization of novel large capacity high‐speed permanent magnet generator

AbstractRecently, the development trend of large capacity generator has gradually shifted from electrical excitation generator to permanent magnet generator (PMG). As a result, the large capacity high‐speed permanent magnet generator (HSPMG) with high power density and high efficiency have received widespread attention. This paper aims to analyse the loss optimization of novel large capacity HSPMG under multi‐operating conditions. In terms of the parameter requirements, a 2.5 MW and 7000 rpm HSPMG is designed. To verify the accuracy of simulation model and the rationality of generator design, the output characteristics of large capacity HSPMG which has been combined with prototype experimental data are calculated under both no‐load and load conditions. Based on the load power characteristics of large capacity HSPMG, the optimization range of the magnetization angle under multi‐operating conditions is explored. By analysing the no‐load back electromotive force (EMF) and loss characteristics of large capacity HSPMG, the optimal magnetization angle that corresponds to the minimum loss under three conditions is obtained. The correctness of the analysis and optimization method is verified by comparing the loss distribution and electromagnetic results before and after the optimization. The research results provide a reference for the multi‐operating characteristics analysis and loss optimization of large capacity HSPMG.

Analysis of forces on nodules during Coandă-effect-based hydraulic collection

The nodule pickup device is a crucial component of a deep-sea mining system. It is widely perceived that leveraging water flow for the separation and retrieval of nodules is a promising approach. A series of experiments and numerical simulations were conducted to examine the impact of non-dimensional parameters on the force characteristics and flow field of the particle in Coandă-effect-based hydraulic collection. The results showed that the lift coefficient of the particle initially increased before subsequently diminishing from the jet nozzle to the rear. Notably, the lift coefficient α reached its maximum at the convex curved surface between x/d = −0.17 and 0.33. Furthermore, a distinct linear correlation was established between the maximum lift coefficient αmax and Froude number Fr across varying h/d, and an empirical formula for predicting the lift coefficient was developed through data fitting. Upon experimental validation, the prediction exhibited a maximum error of less than 20%. Additionally, numerical simulations revealed that the particle significantly influenced the flow dynamics within the collection area, and the flow field characteristics and the particle forces can be corroborated with each other. The findings not only provided a reliable quantitative tool for assessing the particle force but also facilitated precise predictions of collection performance, aiding in the selection of optimal operational parameters in deep-sea hydraulic collection.

Investigation of liquid sloshing characteristics in tanks using an OpenFOAM solver with arbitrary excitation

A multiphase flow solver with mesh motion is typically used for simulations of liquid sloshing in containers, such as those in spacecraft, aircraft, and ships. The mode of the mesh motion should be predefined by functions, which is difficult for a sustained and arbitrary motion. In the present work, a general solver without mesh motion for liquid sloshing in tanks is proposed, based on the interFoam solver in OpenFOAM, by tracking the free surface using the volume of fluid method. An arbitrary excitation loading algorithm is implemented for automatically loading the three-dimensional arbitrary acceleration data. Moreover, the energy equation with phase change is also newly implemented in this solver so that the heat and mass transfer can be evaluated for cryogenic fuels during sloshing. In this way, arbitrary external excitations can be directly imported for any arbitrary sloshing case, and the characteristics of liquid sloshing and oscillation forces can be directly simulated without mesh motion. The solver is validated using different cases, and the influence of sloshing on the mass transfer rate and the effect of the baffle on the liquid sloshing characteristics are investigated. The results indicate that the solver can be easily applied to engineering problems involving liquid sloshing.

Expansion force signal based rapid detection of early thermal runaway for pouch batteries

With the extensive application of lithium-ion batteries in electric vehicles and energy storage stations, thermal safety issues have increasingly become the focus of public attention. To alleviate the safety concerns, a qualified battery management system (BMS) must be able to detect and warn of thermal abuse before it develops into a thermal runaway (TR). For the first time, the expansion force characteristics of the pouch battery module during the early heating stage of TR under typical working conditions are analyzed, which proves that the expansion force signal can reflect the internal abnormal heating earlier than the terminal voltage and the surface temperature, and has better noise resistance. Furthermore, the electromechanical coupling model (EmCM) is improved for more accurate open-loop expansion force estimation. On this basis, an expansion force based early TR rapid detection framework is proposed with less 3 min expend in tests, in which the Kalman filter ensures the stability and convergence/divergence of the observer estimation error, and the reliability of fault judgment is ensured by the adaptive threshold designed by the model structure.

An investigation into the surface integrity and cutting force characteristics in Titanium alloy end milling using soluble oil and MQL as coolants

An investigation into the surface integrity and cutting force characteristics in Titanium alloy end milling using soluble oil and MQL as coolants

An Experimental Study on the Force Characteristics and Stability of an FRP Pipe Floating in Mud

Based on the occurrence of floating and fracture accidents of FRP pipes on muddy seabeds in practical engineering combined with the water intake and drainage project of the 2 × 660 MW coal-fired power plant in the second phase along the coast of Vietnam, a model test study was carried out. The laboratory simulated the FRP pipe conditions during the construction and operation periods by configuring different densities of silt. The experiment results obtained are as follows: the FRP pipes floated up in the mud during the construction period; the thickness of sediment deposition when the FRP pipes are lifted up, as well as the entire lifting process time and maximum force, are all within 2 h and 70 kN/m; after adopting a cover layer design section during the operation period, the FRP pipes in the silt remain stable while obtaining a maximum force of 15 kN/m; and based on the experimental results, an empirical formula for the stress on FRP pipes and was derived and measures for FRP pipe stability were proposed. The research results not only solve practical problems in water intake and drainage engineering but also provide technical support for the promotion and application of FRP pipes.

Two-mode subharmonic generating system with coherent and thermal light

The statistical and squeezing characteristics of the light generated by a two-mode subharmonic generating system in a cavity pumped by two-mode coherent light and coupled to a two-mode thermal reservoir through a single-port mirror have been studied in this study. We construct the c-number Langevin equations linked to the normal ordering using the master equation for the system under discussion, and we establish the correlation characteristics of the noise forces. The mean and variance of the photon number of the cavity light are then determined using the solutions of the resulting differential equations. We have discovered that the cavity light mode’s photon statistics are super-Poissonian because the variance of the photon number is more significant than the mean of the photon number. Additionally, using the same solutions, we were able to extract the antinormally ordered characteristic function, which is used to calculate the Q function. In addition, the photon number distribution for the cavity mode is computed using the Q function. The variance of the plus and minus quadrature of the two-mode cavity light generated by the two-mode subharmonic generating system is also obtained. It is discovered that the cavity mode’s squeezing characteristics are unaffected by the two-mode driving coherent light, however, the thermal light has the effect of decreasing the squeezing of the cavity light and the squeezing takes place in the plus quadrature. Finally, we discovered that when the cavity is coupled to a vacuum reservoir, there is a 50%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} maximum squeezing of the two-mode cavity at a steady state and at the threshold. The nondegenerate subharmonic generator generates a two-mode cavity light that is 50%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} entangled.

Comparative Evaluation of Interaction Force Characteristics for the Lipopolysaccharide of Yersinia pseudotuberculosis and Antibodies by Optical Trapping and Atomic Force Microscopy

Optical tweezers and atomic force microscopy were used for comparative evaluation of the interaction force between the lipopolysaccharide of Yersinia pseudotuberculosis and monoclonal antibodies. This paper discusses the peculiarities of two methods which allow determining significant differences in the values of the measured force required to rupture the interaction of probe sensitized by lipopolysaccharide (polystyrene microsphere for optical tweezers and silicon nitride cantilever for atomic force microscopy) with substrate (glass and mica, respectively) covered with monoclonal antibodies. In atomic force microscopy, the cantilever slides along the substrate for some time after the piezo stage is brought to a stop, causing changes in the spatial structure of sensitins and, therefore, redistribution of multiple bonds between the lipopolysaccharide agglomerate and antibodies. No significant displacement of the microsphere along the substrate occurs when an optical tweezers setup is used, and, unlike atomic force microscopy, the breaking of a complex bond between lipopolysaccharide and complementary antibodies is recorded in the form of a single and short-term (1–2 ms) leap of the photodetector signal employing optical tweezers. The recorded values of the force required to rupture the interaction measured by both methods are relative and vary depending on the chosen experimental conditions. It is shown that the non-specific component of the force needed to break the interaction measured by atomic force microscopy is significantly higher than that determined with optical tweezers.

Study on bearing characteristics of single pile in heterogeneous layered foundation

Based on a project in Lanzhou City, Gansu Province, China, the bearing and internal force characteristics of 2 piles of different lengths under vertical load were tested and analyzed by using BOFDA technology and anchor pile method static load test. The results show that long pile has higher vertical bearing capacity and greater elastic working range, but the axial force of long pile and short pile has the same trend. The lateral friction resistance of the soil layer around the pile plays a role earlier than the pile tip resistance, and the lateral friction resistance of the upper soil layer plays a role earlier than the lower soil layer. The increasing amplitude of lateral friction resistance in different soil layers is also different. The settlement of short pile top is mostly caused by the displacement of pile bottom, and the pile tip resistance is more affected by the pile tip sediments. The relationship between pile end resistance and displacement under the influence of sediments can be analyzed by three-fold line model.

Full-scale test of disc cutter rotary cutting in TBM tunnelling: a case study of Mawan granite in Shenzhen, China

Understanding the distribution of cutting force provides a foundation for the design and optimization of cutterhead layout. The simulation of rotary cutting with a large cutting radius remains a challenge for laboratory tests. In this study, taking the driving condition of the Mawan Tunnel located in the Guangdong-Hong Kong-Macao Greater Bay Area as a case study, a full-scale rotary cutting platform with large cutting radius was used to investigate the rock-breaking effects. Rotary cutting with cutting depths of 1–8 mm and cutting radii of 200–1400 mm were carried out on the granite testing platform using a 19-in disc cutter. The normal force, rolling force, and side force during the cutting process were systematically monitored. Moreover, the time–frequency characteristics of the rock breaking process and the effects of cutting depth, cutting radius and stress state on the average and peak loads were investigated. The results show that the average normal force and rolling force increased with increasing cutting depth, while the side force was less affected by cutting depth through the Boltzman model analysis. The average normal force and rolling force were not significantly affected by the cutting radius, but the average side force decreased as a power function with increasing cutting radius, and showed a stable side force when the installation radius exceeded 1000 mm. The dominant frequency of the cutting force was 0–1.2 Hz, exhibiting notable low-frequency characteristics. Additionally, the ratio of peak to average (RPA) with respect to triaxial cutting force demonstrated an increase with the growth of cutting depth, while RPA in terms of side force exhibited a corresponding growth with the increasing cutting radius. In particular, the cutting force characteristics of the cutterhead obtained in this study can inform the layout of disc cutters and real-life TBM operations, thereby avoiding severe overloading of internal disc cutters.

Energy-saving mechanism and dynamic characteristics of blade angle adjustment in low head pumping system

To investigate the energy-saving mechanisms and dynamic characteristics of blade angle adjustment, this study proposes a novel research method via simulations, prototype and model testing. For stable conditions, the internal field, the external and energy characteristics of the pumping system with different blade angle are examined. The dynamic characteristics of the pumping system and the blade force characteristics during the adjustment process are also studied. The research results show that, under a certain net head, an appropriate impeller blade angle improves the flow state in the pump and conduits, decreasing the entropy production and providing suitable inlet circulation to reduce the hydraulic loss of outlet conduit, thereby improving the pumping system efficiency by 5–10 percentage points. During the adjustment process, there is an approximate 20-s delay in dynamic characteristics. Additionally, with the increase of the blade angle, the hydraulic torques for blade axis and pump shaft increase, thus increasing the blade adjustment force and shaft power. The adjusting force is found to be underestimated in the adjustment processes of decreasing the blade angle. Achievements of this paper contribute to high efficiency of pumping system and high reliability of blade adjustment devices and pump units.

Analysis of rotor vibration characteristics of surface mounted permanent magnet synchronous motor under air gap eccentricity fault

Taking a permanent magnet synchronous motor as the research object, the effect of air gap eccentricity fault on the vibration response characteristics of the motor rotor is analyzed through theoretical calculations, numerical simulation and finite element simulation. First, the change of air gap magnetic field under air gap eccentricity fault is analyzed, and then further calculated to obtain the unbalanced magnetic force under air gap fault by the expression of air gap magnetic field, at last, the rotor’s vibration response characteristics under the action of unbalanced electromagnetic force are obtained by the Newmark- β calculation method. Detailed analysis of the effects of eccentricity distance, eccentricity angle and motor pole-pair number on motor rotor vibration. Finally, the synchronous motor eccentricity fault model is built in ANSYS Maxwell electromagnetic simulation software, and the change characteristics of rotor unbalanced magnetic force after eccentricity fault are calculated and the results are consistent with the theoretical calculations.

Comparative Analysis of Armature Structure on Constant Force Characteristics in Long-Stroke Moving-Iron Proportional Solenoid Actuator

The influence of key design parameters on the constant force characteristics of long-stroke moving-iron proportional solenoid actuators (MPSAs) has been explored by a method combining finite element modelling and correlation analysis. First, the finite element model (FEM) of long-stroke MPSA was developed and validated. Subsequently, the two evaluation indexes, the average-output solenoid force and maximum-output solenoid force variability, were introduced to disclose the influence law of pole shoe parameters on the constant force characteristics of a long-stroke MPSA. After that, correlation analysis was employed to quantify the influence of several parameters and parameter interaction factors on the constant force characteristics. The results indicate a strong contradiction between the average-output solenoid force and maximum-output solenoid force variability; however, increasing the inner diameter of the cone helps enhance the average-output solenoid force without causing maximum-output solenoid force variability to increase. Among all the parameters examined, the cone angle is the most significant parameter affecting the constant force characteristics. Additionally, interactions between the cone angle and the cone length, the cone angle and the inner cone diameter, the cone angle and the outer cone diameter, the cone length and the outer cone diameter, as well as the inner cone diameter and the outer cone diameter also have an important influence on the constant force characteristics. This study deepens our understanding of how the key parameters affect the constant force characteristics and assists designers in optimizing these parameters for developing new structures.

Predicting vertical ground reaction force characteristics during running with machine learning.

Running poses a high risk of developing running-related injuries (RRIs). The majority of RRIs are the result of an imbalance between cumulative musculoskeletal load and load capacity. A general estimate of whole-body biomechanical load can be inferred from ground reaction forces (GRFs). Unfortunately, GRFs typically can only be measured in a controlled environment, which hinders its wider applicability. The advent of portable sensors has enabled training machine-learned models that are able to monitor GRF characteristics associated with RRIs in a broader range of contexts. Our study presents and evaluates a machine-learning method to predict the contact time, active peak, impact peak, and impulse of the vertical GRF during running from three-dimensional sacral acceleration. The developed models for predicting active peak, impact peak, impulse, and contact time demonstrated a root-mean-squared error of 0.080 body weight (BW), 0.198 BW, 0.0073 BW seconds, and 0.0101seconds, respectively. Our proposed method outperformed a mean-prediction baseline and two established methods from the literature. The results indicate the potential utility of this approach as a valuable tool for monitoring selected factors related to running-related injuries.

Seismic capacity evaluation of a reinforced concrete frame infilled with precast modular block wall for enhancing the horizontal load

In this study, we propose a new concept for seismic retrofitting using precast modular block walls (PMBWs) to improve and complement the shortcomings of conventional retrofitting methods for reinforced concrete (RC) frames infilled with shear walls, masonry walls, and precast panels. The PMBW retrofitting method maximizes the advantages of factory-produced modular blocks, innovatively enhancing the constructability and integrity of connections between the existing frame and the infilled PMBW. Additionally, the PMBW reinforcement method improves seismic resistance without significantly increasing structural weight, and the required amount of reinforcement can easily be calculated because the strengthening technique involves typical frame infilling. For RC buildings with non-seismic details dominated by shear failure, the application of this seismic reinforcement method readily ensures sufficient strength. A pseudo-dynamic test was conducted on a full-scale two-story frame, based on an existing RC building with non-seismic details, to evaluate the restoring force characteristics, strength enhancement effects, reinforcement strain, and seismic response control capabilities of the PMBW reinforcement system. Based on the pseudo-dynamic test results, the restoring force characteristics for nonlinear dynamic analysis of the PMBW-reinforced specimen were identified. Finally, nonlinear dynamic analysis was conducted using the proposed restoring force characteristics, and the results were compared with the pseudo-dynamic test results. The unreinforced RC frame experienced shear failure at a design basis earthquake magnitude of 200 cm/s2. However, the frame reinforced with the PMBW sustained only minor damage. Even at higher magnitudes under maximum considered earthquake conditions of 300 cm/s2 and large-scale earthquake conditions of 400 cm/s2, only a slight amount of damage was projected from the analysis. Thus, the newly developed PMBW frame infilling system shows great promise for seismic reinforcement.

Hydrodynamic optimization and performance verification of fairings for round-ended cofferdams using dam-break wave experiments and numerical simulations

Round-ended cofferdams are crucial for large-scale marine projects but are vulnerable to the complex marine environment, including waves, tides, and storms. Enhancing the hydrodynamic performance of these cofferdams is essential for improving safety and efficiency in marine construction. This study introduces a novel fairing design aimed at reducing water flow resistance during the quasi-stable stage of a tsunami. The flow field is analyzed using computational fluid dynamics (CFD) simulations, and an adaptive surrogate model is employed to optimize the parameterized fairing shape. The results demonstrate that the optimized shape significantly suppresses vortex shedding, leading to a 16.59 % reduction in the drag coefficient and a 44.3 % reduction in the lift coefficient under flow conditions. Experimental and numerical simulations of dam-break waves are conducted for two designs, R1 and R0. By comparing their flow field and force characteristics, it is found that R1 effectively separates waves during the impulse stage, reduces wave climb height, and decreases impact loads. In the quasi-stable stage, R1 mitigates the blockage effect, reducing the liquid level difference between the front and back, and thus lowering flow forces. Experimental data further reveals that when the downstream is a dry riverbed, R1′s load reduction is particularly notable, with maximum reductions of 45.62 % in the impulse stage and 28.75 % in the quasi-stable stage. When the riverbed is wet, the maximum load reduction rates are 18.04 % and 8.72 %, respectively. Therefore, R1 not only reduces the resistance of round-end cofferdams under water currents but also under extreme wave forces, providing valuable insights for advancing ocean engineering design.

Uncertainty study of two-phase flow distribution characteristics measurement based on bubble trajectory tracking method

Bubbles undergo complex motions such as nonlinear trajectories in two-phase flow, where the position, velocity magnitude, and direction of bubble centers continuously change as they evolve under the influence of forces. The complexity of bubble trajectory increases the difficulty in measuring the flow field distribution characteristics, which has been understudied in the previous. The bubble trajectory tracking model based on the Monte Carlo method is constructed to study the uncertainty of two-phase flow distribution characteristics measurement by the conductivity probe. The Monte Carlo method is adopted to randomly generate the bubble velocity at the initial moment and the bubble force characteristics are embedded to simulate the three-dimensional motion of the bubble. The influence of various factors on the distribution of effective bubble numbers and velocity relative error at the local point is quantitatively analyzed. It is found that the lateral spacing of the sensors has the greatest influence on the measurement results of small-sized bubbles, the accuracy is greatly reduced when the space is larger than the radius of the measured bubbles. Moreover, the measurement accuracy of the probe for medium-sized bubbles is high, and the effect of bubble lateral velocity and aspect ratio on the effective bubble ratio and velocity relative error is negligible. In addition, the maximum measurement range of the probe at local points is investigated which is found to be 4 mm in the lateral direction and 2 mm in the longitudinal direction. Finally, uniformly distributed bubbles are generated in a 20 mm × 10 mm transverse plane and the distribution of the effective bubble ratio of the probe is found to be consistent at different measurement points, which verifies the reliability of the probe measurement.

Analysis and study of transient characteristics of hydrogen circulation pump under different stopping modes

The internal flow field of the hydrogen circulation pump becomes more complex and flow process becomes more intense during the stopping process, strong vibration is generated to the pump and the working life of the pump is shortened. Therefore, the pressure pulsation at the inlet and outlet section, the radial force characteristics of the active rotor and the transient flow mechanism of the internal flow under different stopping modes are studied in this paper. The results show that the intake pressure and exhaust flow change greatly in exponential stopping mode, while the pressure pulsation amplitude decreases with the increase of stopping time in linear stopping mode. In addition, the radial force value of the active rotor in the exponential stopping mode is significantly smaller than that in the linear stopping mode, and the direction of the radial force Fx and Fy point to the negative direction of their respective axes.