Force Levels Research Articles

Effects of transcutaneous electrical nerve stimulation on evoked tactile sensation for fingertip force control

BackgroundThe bidirectional communication between the hand and brain is profoundly reliant on tactile perception. Transcutaneous electrical nerve stimulation (TENS) can evoke tactile sensation, but its role in fingertip force control is not well understood. PurposeWe examined the tactile sensation evoked by TENS, especially the effects of concurrent modulation of TENS parameters compared to individual-parameter modulation on fingertip force control in both continuous (with dynamic stimulation force) and discrete (with static stimulation force) paradigms. MethodsCo-modulation was accomplished by linearly alteringTENS pulse width and frequency in fixed proportions either positively (both pulse width and frequency increased and decreased simultaneously) or negatively (one increased while the other decreased) at a given “stimulation” force level applied by an instructor. Subjects then generated a “response” force with their fingertips to demonstrate the strength of perceived tactile sensation. The mean, maximum, and duration of response forces and the ratios of response force to stimulation force were examined in different phases and consecutive trials of stimulation. ResultsThe positive and negative co-modulations led to stronger and longer duration response sensitivity than the individual modulations. In addition, subjects could effectively discriminate the evoked tactile sensation variations with co-modulated stimulation parameters from the lower to the higher modulation intensities. The co-modulations were more likely to cause sensory adaptations than the independent modulations. ConclusionThe findings of this study suggested that the co-modulated TENS can result in effective responses to tactile sensation when stimulation trials are controlled. The TENS with co-modulation may serve as an effective tool for eliciting tactile sensations for precise fingertip force control. The findings of this study may play a role in developing bidirectional hand/digit prostheses or restoring hand sensorimotor function.

Identification of creep parameters from multi‐step relaxation tests on miniaturised specimen

AbstractThe small punch test (SPT) is a miniaturised method for thermo‐mechanical materials testing. The combination of simple specimen geometry and low required specimen volume is ideal for minimally invasive characterisation and monitoring of the current material condition in technological systems, including nuclear plants.The aim of the present study is to identify creep material properties of the chromium steel P91 (X10CrMoVNb9‐1) via small punch testing. It is examined to which extent a single relaxation test is suitable to replace several creep tests at different force levels. The inverse parameter identification method utilises a non‐linear optimisation approach in order to match the results of simulation and experiment. The simulation is performed using finite element analysis (FEA) and the considered material law aims to represent the high‐temperature behaviour of steels. To this end, a modified Liu–Murakami model is specifically used along with linear elasticity and non‐linear isotropic plasticity. We propose a strategy, that can be used to separately identify the Norton‐parameters from multi‐step relaxation tests performed on one specimen. Thereby, the applied strain (displacement, if utilising SPT) is kept constant after initial loading, which enables stress relaxation within the specimen. In case of the SPT, this behaviour yields a decreasing reaction force which approximately approaches a constant value. During the repeated loading phases, specimen failure may occur, due to further plastification of the specimen. Loading and relaxation cycles are repeated until specimen failure.The identified parameters are validated via small punch creep experiments at different force levels. It will be shown that good agreement is observed when comparing the sets of identified parameters.

Development of a novel wrist pulse system for early diagnosis of pathogenic bacterial infections using optimized feature selection with machine learning approaches

Pelvic inflammatory disease (PID) and urinary tract infections (UTI) are two Pathogenic bacterial infections. PID affects the female reproductive system, whereas UTI affects the urine system. Females are more vulnerable to both forms of illnesses and challenging to detect simultaneously due to similar symptoms. Many Clinical procedures have previously been used to diagnose the diseases, but they are painful, costly, prone to radiation, and invasive. Therefore, this paper proposed the Ayurvedic and Traditional Chinese Medicine [TCM] based wrist pulse measurement to diagnose these bacterial infections non-invasively. An Artery tonometry-based test prototype was designed to measure the pulse signals at three doshas (Vata, Pitta, Kapha) locations on the radial artery under variable static force. The data is recorded at an intermediate force level to get maximum accuracy. Signals feature viz., time domain feature, autoregressive (AR) model features, approximation entropy, sample entropy, and multiscale entropy have been calculated. Further, the efficiency of the machine learning model is enhanced through optimization-based feature selection techniques. Three different optimization-based feature selection, viz., whale optimization (WOA), ant colony optimization (ACO), and proposed binary Greywolf optimization (BGWO), has been proposed to acquire the optimized features subsets for accurate classification of disease subjects. These subsets have been used by popular machine learning techniques to classify the PID and UTI. The results of the experiment demonstrate that as the static force changed, the wrist pulse signal first increased to an intermediate force level and then decreased. Second, the classification accuracy of the machine learning model with feature selection is more than conventional feature classification. Third, the wrist pulse analysis (WPA) shows the maximum accuracy in comparison to conventional clinical PID diagnosis, where Vata dosha has the highest classification accuracy (94.1%) when using BGWO-SVM, followed by Pitta dosha (88.2%) when using BGWO-BNN. Similarly, specificity has been used for UTI classification, where Vata dosha has the highest specificity of 100% with BGWO-SVM, followed by pitta dosha with 83.3% BGWO-BNN. Finally, three dosha classification findings demonstrate that Vata and Pitta doshas have been more significantly impacted, as they have the highest classification accuracy compared to conventional clinical diagnosis, which produces similar results consistent with ayurvedic literature. Therefore, WPA can provide a unique diagnostic method for early PID/UTI identification.

Research on the Calculation Model and Control Method of Initial Supporting Force for Temporary Support in the Underground Excavation Roadway of Coal Mine

This paper proposes a temporary support system for improving the efficiency and safety of underground roadway excavation in coal mines. Firstly, this study establishes a calculation model for the initial supporting force of the excavation of roadway temporary support and a gray system-based automatic prediction model for the initial supporting force level, based on the mechanism of temporary support controlling the roof. These models enable the prediction of the required initial supporting force at different locations along the roadway’s temporary support area, thereby providing a basis for controlling the initial supporting force of the temporary support system. To achieve efficient and adaptive control of the initial supporting force of temporary supports at different locations, this study designs a support force controller based on Simulated Annealing Particle Swarm Optimization Proportional-Integral-Derivative (SAPSO-PID). This study establishes a mathematical model for the hydraulic cylinder pressure system controlled by the temporary support overflow valve and conducts a stability analysis and model verification. The study constructs a simulation control system for the initial supporting force based on SAPSO-PID using the combined simulation platform of AMESim and Matlab. The simulation results demonstrate that the proposed support force control system efficiently achieves adaptive control of the initial supporting force of temporary supports. An experimental system in the underground roadway of a coal mine is constructed to validate the results of the simulation analysis.

Occlusal Contact Changes With Traumatic Occlusion After Orthodontic Treatment: A Prospective Study

Aim: The aim of this study was to evaluate trauma from occlusion in patients undergoing orthodontic treatment through assessment of fremitus, pocket depth, gingival biotype, and occlusal contacts pre-orthodontic treatment (T0) and post-orthodontic treatment (T1). Materials and Methods: This prospective randomized trial included 40 participants selected based on a simple random sampling method, of which 27 were women and 13 were men with ages ranging from 25 to 40 years. All the participants were clinically checked for gingival recession, fremitus, pocket depth, gingival biotype, and occlusal contacts obtained via digital intraoral scans and fed to 3Shape software to perform the occlusal mapping analysis for pre-orthodontic treatment (T0) and post-orthodontic treatment (T1). T-Scan occlusal analysis was performed to check the force levels pertaining to each tooth. A paired t-test was done to find out the changes in fremitus, pocket depth, gingival biotype, and number of occlusal contacts between T0 and T1. Results: Results of paired t-tests showed a statistically significant difference for fremitus between T0 and T1 ( p < .05). Gingival biotype and pocket depth did not show any improvement post-orthodontic treatment (T1) ( p > .05). Number of traumatic occlusal contacts reduced at T1 for incisors and canines showing a statistically significant difference between T0 and T1 ( p < .05). Conclusion: Orthodontic treatment helps in relieving the traumatic occlusal contacts, especially in the incisors and canine regions. As the teeth are relieved from traumatic occlusal contacts, fremitus also has shown to have drastically improved at the end of orthodontic treatment. Gingival biotype and pocket depth might take a longer time to regenerate and improve, which requires long-term observation.

Posterior restoration rotational torque associated with cuspal incline angulation: A proof of concept

Off-axis, external forces with a moment arm on posterior restorations have not been investigated in experimental studies. The purpose of this proof-of-concept study was to determine the interaction between occlusal force directed toward cuspal incline angulations with variations in base width and preparation vertical heights. Torque forces on a single crown restoration in simulated premolar and molar tooth forms were calculated for 3 different rotational axes. Trigonometric calculations were made to determine the amount of torque generated in a simulated-crown restoration in premolar and molar tooth forms. Restorations with different cuspal incline angulations were loaded with an off-axis force of 200N. This force was applied to 5 different cuspal incline angulations in both tooth forms at varying preparation heights. Right triangles were used to enable trigonometric computations of the resulting moment arms that accompanied the 3 rotational axes. The total torque values were calculated with a range from 7.5 to 372.8 Ncm. The highest levels of torque were generated in the 5-mm-high molar tooth form with a rotational axis located within the root form, perpendicular to the 45-degree cuspal incline. In general, large moment arms were generated with steep cuspal incline angulations and mid-root axis locations; the lowest torque values in all cuspal incline angulations were found in the rotational axis locations at the crown finish line. The torque values at the rotational axis finish line location were found to be greatest in the largest vertical tooth form height category (5mm) in both tooth model sizes. The crown restoration cuspal incline angulations, vertical preparation heights, base widths, and rotational axis locations all played a role in the torque force levels generated, probably influencing restoration stability.

Effects of postural threat on the scaling of anticipatory postural adjustments in young and older adults.

The ability to scale anticipatory postural adjustments (APAs) according to the predicted size of the upcoming movement is reduced with aging. While age-related changes in central set may be one reason for this effect, an individual's emotional state might also contribute to changes in anticipatory postural control. Therefore, the purpose of this study was to determine whether an altered emotional state, as elicited through postural threat, alters the scaling of APAs during a handle pull movement in young and older adults. It was hypothesized that the presence of postural threat would lead to more homogenous APAs (i.e., less scaling of APAs) across a range of pulling forces. Young (n = 23) and older adults (n = 16) stood on top of a force plate that was mounted to a motorized platform. From this position, participants performed a series of handle pull trials without (no threat) or with (threat) the possibility of receiving a postural perturbation in the form of an unpredictable surface translation. Handle pulls were performed at force levels between 50 and 90% of maximum force. For each trial, the magnitude and timing of the APA were quantified from center of pressure (COP) recordings as well as electromyographic (EMG) activity of the soleus and medial gastrocnemius. The scaling of APAs with respect to force exertion was then determined through regression analyses and by comparing APAs during pulls of lower versus higher force. As evidenced by their smaller slope of the regression line between various dependent measures (i.e., COP velocity, soleus EMG onset latency, and soleus EMG amplitude) and the pulled forces, older adults demonstrated less scaling of APAs than the young. However, increases in arousal, anxiety and fear of falling due to postural threat, only minimally altered the scaling of APAs. Regardless of age, the slope of the regressions for none of the measures were affected by threat while only the soleus and medial gastrocnemius EMG onsets demonstrated significant force × threat interaction effects. These results suggest that the decreased ability to scale APAs with aging is unlikely to be due to changes in emotional state.

Study on the Frontal Collision Safety of Trains Based on Collision Dynamics

The high-speed collision issue brought on by railway vehicles’ intensive and high-speed operation has become a critical concern for operational safety. Therefore, it is necessary to research the high-speed collision problem of trains. Firstly, a train collision dynamic model suitable for higher collision velocities is established. This model includes a 38-degree-of-freedom (DOF) three-dimensional vehicle model and a three-layered vibrating fixed-track model. Corresponding mathematical models are developed for nonlinear factors such as wheel–rail contact, car–end contact, and coupler overload representation in the model. Then, the Train Collision State Score (TCSS) is proposed, enabling quantitative safety evaluation under different collision conditions. Finally, the influence of the energy-absorbing device’s initial attitude and leading car parameters on collisions is studied. The results indicate that initial vertical height difference and pitching angle significantly increase TCSS. As the force level of the energy-absorbing device of the leading car increases, the effects of two intermediate coupler overload states on TCSS show opposite trends.

Multiple regions of sensorimotor cortex encode bite force and gape.

The precise control of bite force and gape is vital for safe and effective breakdown and manipulation of food inside the oral cavity during feeding. Yet, the role of the orofacial sensorimotor cortex (OSMcx) in the control of bite force and gape is still largely unknown. The aim of this study was to elucidate how individual neurons and populations of neurons in multiple regions of OSMcx differentially encode bite force and static gape when subjects (Macaca mulatta) generated different levels of bite force at varying gapes. We examined neuronal activity recorded simultaneously from three microelectrode arrays implanted chronically in the primary motor (MIo), primary somatosensory (SIo), and cortical masticatory (CMA) areas of OSMcx. We used generalized linear models to evaluate encoding properties of individual neurons and utilized dimensionality reduction techniques to decompose population activity into components related to specific task parameters. Individual neurons encoded bite force more strongly than gape in all three OSMCx areas although bite force was a better predictor of spiking activity in MIo vs. SIo. Population activity differentiated between levels of bite force and gape while preserving task-independent temporal modulation across the behavioral trial. While activation patterns of neuronal populations were comparable across OSMCx areas, the total variance explained by task parameters was context-dependent and differed across areas. These findings suggest that the cortical control of static gape during biting may rely on computations at the population level whereas the strong encoding of bite force at the individual neuron level allows for the precise and rapid control of bite force.

Development of a Ratiometric Tension Sensor Exclusively Responding to Integrin Tension Magnitude in Live Cells.

Integrin tensions are critical for cell mechanotransduction. By converting force to fluorescence, molecular tension sensors image integrin tensions in live cells with a high resolution. However, the fluorescence signal intensity results collectively from integrin tension magnitude, tension dwell time, integrin density, sensor accessibility, and so forth, making it highly challenging to specifically monitor the molecular force level of integrin tensions. Here, a ratiometric tension sensor (RTS) was developed to exclusively monitor the integrin tension magnitude. The RTS consists of two tension-sensing units that are coupled in series and always subject to the same integrin tension. These two units are activated by tension to fluoresce in separate spectra and with different activation rates. The ratio of their activation probabilities, reported by fluorescence ratiometric measurement, is solely determined by the local integrin tension magnitude. RTS responded sensitively to the variation of integrin tension magnitude in platelets and focal adhesions due to different cell plating times, actomyosin inhibition, or vinculin knockout. At last, RTS confirmed that integrin tension magnitude in platelets and focal adhesions decreases monotonically with the substrate rigidity, verifying the rigidity dependence of integrin tensions in live cells and suggesting that integrin tension magnitude could be a key biomechanical factor in cell rigidity sensing.

Mechanical Properties of Bio-Based Sandwich Composites Containing Recycled Polymer Textiles.

In this paper, sandwich composites were produced by compression moulding techniques, and they consisted of regenerated cellulose fabric (rayon) and bio-based polypropylene (PP) to form facings, while virgin and recycled polyamide (PA) textiles were used as core materials. To compare the mechanical performance between sandwich composites and typical composite designs, a control composite was produced to deliver the same weight and fiber mass fraction from rayon and PP. To evaluate the influence of recycled textile on the mechanical properties of the composites, a series of flexural, low velocity impact (LVI) and tensile tests were performed. It was found that the incorporation of thicker PA textile enhanced the bending stiffness by two times and the peak flexural force by 70% as compared to those of control. Substitution of a layer of recycled textile for two layers of rayon provided a good level of impact energy absorption capacity (~28 J) and maximum force (~4893-5229 N). The tensile strength of the four sandwich composites was reported to be in the range of 34.20 MPa and 46.80 MPa. This value was 91.90 for the control composite. The 2D cross-section slices of the composite specimens did not show any evidence of fiber tow debonding, fiber bundle splitting, or delamination.

Integrated Flexible Microscale Mechanical Sensors Based on Cascaded Free Spectral Range-Free Cavities.

Photonic mechanical sensors offer several advantages over their electronic counterparts, including immunity to electromagnetic interference, increased sensitivity, and measurement accuracy. Exploring flexible mechanical sensors on deformable substrates provides new opportunities for strain-optical coupling operations. Nevertheless, existing flexible photonics strategies often require cumbersome signal collection and analysis with bulky setups, limiting their portability and affordability. To address these challenges, we propose a waveguide-integrated flexible mechanical sensor based on cascaded photonic crystal microcavities with inherent deformation and biaxial tensile state analysis. Leveraging the advanced multiplexing capability of the sensor, for the first time, we successfully demonstrate 2D shape reconstruction and quasi-distributed strain sensing with 110 μm spatial resolution. Our microscale mechanical sensor also exhibits exceptional sensitivity with a detected force level as low as 13.6 μN in real-time measurements. This sensing platform has potential applications in various fields, including biomedical sensing, surgical catheters, aircraft and spacecraft engineering, and robotic photonic skin development.

Vertical contact forces affect vibration perception in human hairy skin.

Skin is the largest organ of the human body and fulfills many important functions, like detecting mechanical stimuli. Skin can be divided into glabrous (non-hairy) and hairy skin. These two skin types differ with regard to their mechanical properties and in the distribution of mechanoreceptors. Although many investigations focus on glabrous skin, hairy skin still plays a fundamental role in various activities, e.g., with regard to the perception of pleasantness or for developing wearable vibrotactile devices for pattern recognition in persons with disabilities. Unfortunately, investigations on influencing factors, like vertical contactor force, are scarce for hairy skin. Similarly, it would also be interesting to investigate whether regional vibratory sensitivity differences are present across the human torso. Hence, this study investigated the effects of vertical contactor forces and different anatomical locations on vibration perception. Four anatomical torso regions were studied. Based on findings in glabrous skin, we generally hypothesized improved vibration perception with increasing contactor forces and regional sensitivity differences between the anatomical locations. Forty young and healthy individuals participated (23.0 ± 2.0 yrs), and vibration perception thresholds (VPTs) were determined at 30 Hz for three vertical force levels (0.6, 2.4, and 4.8 N) at four torso locations (sternum, deltoid/shoulder, lower back, middle lateral torso side). Higher contactor forces resulted in lower VPTs corresponding to improved vibration perception, regardless of anatomical location. In addition, the sternum region was more sensitive than the remaining three regions, regardless of force level. The reasons for these findings may be a varying number and activation pattern of afferents activated under the different conditions. The findings of this study complement the understanding of vibrotactile sensitivity in hairy skin and may offer implications when developing vibrotactile devices or clothing/textiles, for example.

A preliminary study evaluating the relationship between force and incised trauma on pig rib bones

In forensic contexts, understanding of the complicated relationships between level of force, type of knife blade, and dimensions of incisions remains limited. The purpose of this research was to explore how incisions on pig rib bones vary depending on the type of knife blade and quantity of perpendicular force inflicted. A cutting rig (designed to position a bone, knife, and weights) facilitated the creation of incisions on fleshed rib bones (n = 59), defleshed rib bones (n = 77), and synthetic materials (n = 36). Five different masses of weights (measuring 4381, 8861, 13515, 18267, and 23343 g) were applied to four knife blades (two serrated and two non-serrated blades), with each combination of variables repeated thrice. 3D digital microscopy was utilized to model and measure each incision. The two-way ANOVA found significant differences in depth and length between knife types and levels of force across all sample sets (p < 0.05), with greater perpendicular forces and serrated blades creating longer and deeper cuts. These findings demonstrate that there is a complex relationship between force, type of knife blade, and the related dimensions of incisions.

Modes of Atmospheric Energetics Based on HadGEM3-GC3.1-LL Simulations in the Framework of CMIP6

In this study, the focus is on investigating how different climate scenarios, as they have been adopted in Phase 6 of the Coupled Model Intercomparison Project (CMIP6), can lead to different regimes in the energetics components in Lorenz’s energy cycle, hence impacting the “working rate” of the climate system, which is considered as a “heat engine.” The four energy forms on which this investigation is based on are the zonal and eddy components of the available potential and kinetic energies. The permissible correspondingly considered transformations between these forms of energy are also studied. Generation of available potential energy and dissipation of kinetic energy complete the Lorenz energy cycle that is adopted here. In the CMIP6 approach, the results of different climate change analyses were collected in a matrix defined by two dimensions: climate exposure as characterized by a radiative forcing or temperature level and socioeconomic development as classified by the pathways, known as Shared Socioeconomic Pathways (SSPs). The basis of the calculations in this study is the climatic projection produced by the HadGEM3-GC3.1-LL climatic model in the period from 2015 to 2100. In this respect, the results are presented in terms of time projections of the energetics components under different SSPs. The results have shown that the different SSPs yield diverse energetics regimes, consequently impacting on Lorenz energy cycle and, hence, a “working rate” of the climate system based on the components of this cycle. In this respect, Lorenz energy cycle projections are presented, under different SSPs. The results are also contrasted to the calculations for the historical period 1929 to 2014 as this is simulated by the same climatic model.

Can Digital Economy Drive Income Level Growth in the Context of Sustainable Development? Fresh Evidence from “Broadband China”

In the context of the rapid development of digital economy and the promotion of sustainable development, this paper focuses on the impact of digital economy on income levels. Based on the panel data of 195 prefecture-level cities, the “Broadband China” pilot has been regarded as a natural experiment for the measurement of the digital economy. In this paper, a time-varying DID model was established to evaluate the influential effect of “Broadband China” on income growth. It was found that the coming into service of “Broadband China” has increased the overall income level of the Chinese labor force. Further research found that “Broadband China” has done more to raise the income levels of the high-skilled labor force, thus widening the income gap between the high-, medium-, and low-skilled labor force. “Broadband China” can affect the income growth via two mechanisms, namely, “increasing the entrepreneurship rate” and “leading to an increase in the overall number of professional and skilled labor force in China”. In this case, the entrepreneurship rate of the high-skilled labor force may be higher than that of the medium- and low-skilled labor force due to human capital accumulation. The rapid increase in the high-skilled labor force in technical industries will lead to the situation where their income growth effect is higher than that of the medium- and low-skilled labor force. Based on the above research results, this paper puts forward policy suggestions from three aspects: further accelerating the process of digital economy; improving the institutional environment of the broadband network and standardizing the order of the construction of the broadband network; and further stimulating the entrepreneurial motivation of labor force, paying attention to the problem of skill bias and optimizing the employment structure, balancing efficiency and equity, and contributing to the ultimate sustainable development of developing countries.

Study of cutting forces during turning of high-hard cast irons

Purpose. Research of cutting force components during machining of high-hard cast iron by special prefabricated cutters with brazed niborite and ciborite inserts. Determination of the influence of geometric characteristics of the cutting tool, cutting modes and hardness of the material being machined on the cutting forces. The methods. The research methods were based on the fundamentals of cutting theory and cutting tools, material science properties of the tool and processed material. A research bench with special equipment was used. Findings. The nature of the change in the components of cutting forces with depth t, feed rate S and cutting speed v was experimentally investigated. The studies have shown an excess of the resulting force in the horizontal plane Pv over the circumferential one Pz, which is the main feature of turning high-hard metals. It has been established that the main limiting factors in the wear of tool cutting inserts are the permissible levels of forces. The hardness of HB has the greatest effect on the radial force Py. Under identical turning conditions for materials with a hardness of 220 to 610 HB, the forces Pz, Py and Px increase by 1,7; 3,3 and 2,3 times, respectively. In addition to the natural increase, the ratio of cutting forces also changes. Reducing the front angle of the blade causes a deterioration in chip formation conditions and leads to an increase in all components of the cutting forces. An increase in the radius at the top of the cutter r causes an increase in the width and decrease in the thickness of the layer to be cut, as well as a decrease in the main angle in the plan φr on the radial part of the blade. The originality. A complex dependence in the structural-stage form was obtained, which gives a clear picture of the influence of each parameter of the turning process on its performance. This dependence is a mathematical model for calculating the optimal operating and geometric parameters of the turning process of high-hard cast irons. The influence of the frontal angle γ, wear value h, and hardness of HB cast iron on the power characteristics during machining of high-hard cast irons has been studied. Practical implementation. It has been shown that it is economically advantageous to maximize the wear of cutting inserts made of relatively expensive composites. In this case, it is necessary to use a technological system of machine-workpiece-tool of high rigidity.

Shaking table tests of masonry wall reinforced with steel-bar truss units linked by spring dampers

Since unreinforced masonry buildings are vulnerable to earthquakes, various studies have been conducted to improve their seismic performance. In this study, spring dampers were added to steel-bar truss units to improve the performance of the reinforcement method, and shaking table tests were performed to evaluate their seismic performance. Furthermore, a full-scale I-shaped masonry wall was prepared by considering the inner walls of masonry buildings, and steel-bar truss units linked by spring dampers were installed on both sides of the specimen. For the unreinforced specimen, the horizontal spectral acceleration calculated for the flexible components was 0.54 g, the seismic loading level was sequentially increased by 20%, and in-plane excitation was performed. The experimental results showed that the unreinforced masonry specimen resisted up to 220% of the designed seismic acceleration, whereas the reinforced masonry specimen resisted up to 320%. At the end of the experiment with the unreinforced masonry specimen, the response peak acceleration and drift ratio of the reinforced specimen were approximately 36% and 50% lower than those of the unreinforced masonry specimen, respectively. This implies that the diagonal bars constituting the truss units reduced the story drift ratio by suppressing shear deformation, and the vertical bars prevented cracking by introducing an additional axial force on the masonry wall. The experimental results demonstrated that the reinforcement method efficiently improved the seismic performance of the masonry wall in terms of stiffness, ductility, shear force. Because this study was conducted with only one variable, i.e., the presence/absence of the strength method, further research with various variables such as a number of steel-bar truss units, prestressing force level, spring stiffness of spring damper is required to verify the practical applicability of the method.

Design and Gait Control of an Active Lower Limb Exoskeleton for Walking Assistance

In the development of assistive lower-limb exoskeletons, both exoskeleton design, and gait control are critical for their successful applications. This paper introduces an assistive lower-limb exoskeleton (ALEXO) for active walking assistance. The development of the ALEXO including mechanical design, sensors and gait control is described. The exoskeleton adopts a hierarchical control. A 2-link model is built for dynamic analysis and lower-level control purposes. A trajectory tracking control method based on the computed torque control is proposed, in which physical interaction between the exoskeleton and the user is included. Simulations were conducted for different levels of interaction forces to verify the feasibility of the gait control. Moreover, walking trials of a healthy subject were performed, with muscle activities measured through EMG systems. Both simulation and system test results demonstrated the effectiveness of the developed exoskeleton with the proposed control method for walking assistance.

Transforming farming with intelligence: Smart vibration monitoring and alert system

During the evolution towards digital agriculture, the pivotal role of tractor riding necessitates a focus on improving operator performance and well-being. While most research has centered around vibration analysis, tangible solutions to control elevated vibration levels remain rare. The study aims to introduce an intelligent ThingSpeak-Enabled IoT (Internet of Things) solution that provides real-time monitoring and generates prompt warning alerts for tractor operators when vibrations exceed safe thresholds. The initial phase involved the real-time measurement of WBV (whole-body vibration) and SEAT (seat effective amplitude transmissibility). Following this, the secondary phase encompassed the analysis and validation of the system in cases where WBV and SEAT exceeded the recommended limits. The experimental design comprised 135 trials by systematically varying tractor ride parameters, including average speed (m/s), average depth (m), and pulling force (kN) levels. Daily vibration exposure response ranged from 0.43 m/s² to 0.87 m/s² with a mean exposure of 0.64 m/s2, surpassing the EAV (exposure action value) threshold of 0.5 m/s². The SEAT values ranged between 91.37 and 133.08 with a mean of 108.35, that indicates insufficient seat isolation capacity, i.e., < 100. Statistically, the study ascertained a significant influence of average speed and average depth WBV and SEAT responses at a 5% significance level. It underscores the potential efficacy of altering speed and depth parameters to attenuate vibration exposure levels. Further, the effectiveness of the system was tested through the automatic transmission of warning alerts via emails, text messages, and flashing red LED light on the IoT system. This critical feature provides considerable utility for tractor operators to adjust ride settings, ensuring that the ride remains within safe vibration limits. Furthermore, adopting such an advanced warning system in tractor manufacturing signifies a pioneering step towards sustainably enhancing operator well-being.