Forces In Different Directions Research Articles

The human central nervous system transmits common synaptic inputs to distinct motor neuron pools during non-synergistic digit actions.

Key points Neural connectivity between distinct motor neuronal modules in the spinal cord is classically studied through electrical stimulation or multi‐muscle EMG recordings.We quantified the strength of correlation in the activity of two distinct populations of motor neurons innervating the thenar and first dorsal interosseous muscles during tasks that required the two hand muscles to exert matched or un‐matched forces in different directions.We show that when the two hand muscles are concurrently activated, synaptic input to the two motor neuron pools is shared across all frequency bandwidths (representing cortical and spinal input) associated with force control.The observed connectivity indicates that motor neuron pools receive common input even when digit actions do not belong to a common behavioural repertoire. Neural connectivity between distinct motor neuronal modules in the spinal cord is classically studied through electrical stimulation or multi‐muscle EMG recordings. Here we quantify the strength of correlation in the activity of two distinct populations of motor neurons innervating the thenar and first dorsal interosseous muscles in humans during voluntary contractions. To remove confounds associated with previous studies, we used a task that required the two hand muscles to exert matched or un‐matched forces in different directions. Despite the force production task consisting of uncommon digit force coordination patterns, we found that synaptic input to motor neurons is shared across all frequency bands, reflecting cortical and spinal inputs associated with force control. The coherence between discharge timings of the two pools of motor neurons was significant at the delta (0–5 Hz), alpha (5–15 Hz) and beta (15–35 Hz) bands (P < 0.05). These results suggest that correlated input to motor neurons of two hand muscles can occur even during tasks not belonging to a common behavioural repertoire and despite lack of common innervation. Moreover, we show that the extraction of activity from motor neurons during voluntary force control removes cross‐talk associated with global EMG recordings, thus allowing direct in vivo interrogation of spinal motor neuron activity.

Apparent Piezo‐Photocurrent Modulation in Methylammonium Lead Iodide Perovskite Photodetectors

AbstractMethylammonium lead iodide perovskite (MAPbI3) have recently been found to have piezoelectricity which can enhance the performance of MAPbI3‐based photodetectors in the form of piezo‐phototronic effects or can be employed in fabricating hybrid photovoltaic devices. In this work, the effect of an external force in different directions on the photocurrent of a lateral structure of an indium tin oxide (ITO)–MAPbI3–ITO photodetector is investigated. The photodetector is fabricated by using the capillary motion of a solution containing the perovskite precursor on a microchannel. The structure is characterized by scanning electron microscopy, X‐ray diffraction, and atomic force microscopy. The current–voltage characteristics and current transient responses are measured under different conditions of dark and light. Additionally, an apparent piezo‐photocurrent modulation is observed under both normal and transverse forces on MAPbI3 by testing the device under normal forces and bending conditions (inward and outward). In the highest state, the photocurrent is increased by 97% when 340 kPa normal force is applied to the device. At this state, the device shows a Iph/Idark of 3250 at 2.0 V bias with a photocurrent of ≈6.9 µA and responsivity of 14.56 mA W−1. These results promise utilizing MAPbI3 in piezotronic applications and hybrid energy harvesters.

Effect of leading ultrasonic vibrations on the welding forces of friction stir lap welding

Influence of leading ultrasonic vibrations on the process forces in the friction stir lap welding of AA 6061-T6 with and without ultrasonic vibrations is investigated at varied welding speeds. The axial force, traverse force, and tool torque in the processes are determined by adopting a recently developed method that uses electrical signals of the servo motors and main spindle AC motor of the friction stir welding machine during the welding process. It is found that the exerted ultrasonic vibrations decrease the welding forces without compromising the mechanical properties of welds. The effect of ultrasonic vibrations on traverse force is more pronounced than that on the tool torque and axial force. Force measurements at different welding speeds indicated that the axial force and traverse force varied significantly with travel speed of tool. Not much difference is found in the tool torque variation. With ultrasonic vibrations, the reduction in welding force in different directions is affected differently by welding speed. The ultrasonic effect on welding forces is found to be governed by the travel speeds of both the tool and workpiece.

Finite element analysis of the effect of power arm locations on tooth movement in extraction space closure with miniscrew anchorage in customized lingual orthodontic treatment.

More patients are choosing customized orthodontic appliances because of their excellent esthetics. It is essential that clinicians understand the biomechanics of the tooth movement tendency in customized lingual orthodontics. This study aimed to evaluate the tooth movement tendency during space closure in maxillary anterior teeth with the use of miniscrew anchorage in customized lingual orthodontics with various power arm locations. Three-dimensional finite element models of the maxilla were created with miniscrews and power arms; the positions were varied to change the force directions. A retraction force (1.5N) was applied from the top of the miniscrews to the selected points on the power arm, and the initial displacements of the reference nodes of the maxillary teeth were analyzed. After applying force in different directions, power arms located at the distal side of the canines led to larger initial lingual crown tipping and occlusal crown extrusion of the maxillary incisors compared with power arms located at the midpoint between the lateral incisors and canines, and caused a decreasing trend of the intercanine width. In customized lingual orthodontic treatment, power arms located at the distal side of the canines are unfavorable for anterior teeth torque control and intercanine width control. Power arms located at the midpoint between the lateral incisors and canines can get better torque control, but still cannot achieve excepted torque without extra torque control methods, no matter whether its force application point is higher than, lower than, or equal to the level of the top of the miniscrews.

Vibro-acoustic responses of a coupled propeller-shaft-hull system due to propeller forces

The vibro-acoustic responses of a submerged propeller-shaft-hull coupled system under propeller forces in different directions are investigated by the coupled finite element/boundary element method. In the analysis, the acoustic transfer vector (ATV) approach is utilized to study the acoustic contribution from the elastic propeller and the hull. By applying the modal decomposition technology, the effects of the stern bearing on the acoustic response of the coupled system under transversal propeller force are observed. The numerical results are compared with those obtained from a hydroacoustic experiment of the propeller-shaft-hull coupled system. The effects of the decreasement of the stiffness of the thrust bearing on the acoustic response of the coupled system are discussed.

Cutting Forces Measurement for Milling Process by Using Working Tables with Integrated PVDF Thin-Film Sensors.

In the milling process, cutting forces contain key information about the machining process status in terms of workpiece quality and tool condition. On-line cutting force measurement is key for machining condition monitoring and machined surface quality assurance. This paper presents a novel instrumented working table with integrated polyvinylidene fluoride (PVDF) thin-film sensors, thus enabling the dynamic milling force measurement with compact structures. To achieve this, PVDF thin-film sensors are integrated into the working table to sense forces in different directions and the dedicated cutting force decoupling model is derived. A prototype instrumented working table is developed and validated. The validation demonstrates that profiles of the forces measured from the developed instrumented working table prototype and the dynamometer match well. Furthermore, the milling experiment results convey that the instrumented working table prototype could also identify the tool runout due to tool manufacturing or assembly errors, and the force signal spectrum analysis indicates that the developed working table can capture the tool passing frequency correctly, therefore, is suitable for the milling force measurement.

Optimal deposition orientation in fused deposition modeling for maximizing the strength of three-dimensional printed truss-like structures

Whether for producing prototypes or functional parts by additive manufacturing, the fused deposition modeling is the most commonly used technique. Nevertheless, not only the hobbyist but also the industrial three-dimensional printers produce parts that suffer from anisotropy in their mechanical properties imposing important limitations on the strength of the manufactured piece. The aim of this work is to propose a strategy for determining the optimal build surface orientation of three-dimensional truss-like structures manufactured using fused deposition modeling. This can be achieved by minimizing the norm of the dot products of the normal direction of the deposition plane (build surface plane) and the directions of the tensile forces. Since three-dimensional trusses are subjected to tensile forces in different directions, a multi-objective cost function was proposed. Moreover, these structures might present rotational symmetry, which should be considered as design constraints. In this work, two three-dimensional truss-like structures were investigated. The nature of the optimization is case dependent and solvers were selected accordingly. Experimental campaigns were carried out for evaluating the specimens manufactured using fused deposition modeling. It could be concluded that higher yield tensile strength could be achieved by adopting the optimal deposition plane. This result demonstrates the applicability of optimization techniques for improving additive manufacturing results.

A novel testing system for biomechanical evaluation of the bone or bone fixator

PurposeBiomechanical properties of bones and fixators are important. The aim of this study was to develop a new device to simulate the real mechanical environment and to evaluate biomechanical properties of the bone with a fixation device, including the static force and the fatigue characters.Design/methodology/approachIn this paper, the device is mainly composed of three parts: pull-pressure transmission system, bending force applying system and torsion applying system, which can successfully simulate the pre-introduced pull-pressure force, bending force and torsion force, respectively. To prove the feasibility of the design, theoretical analysis is used. It is concluded from the simulated result that this scheme of design can successfully satisfy the request of the evaluation.FindingsFinally, on the basis of the force sensor calibration, the static force experiment and fatigue experiment are carried out using the tibia of the sheep as the specimen. It is concluded from the result that the relationship between the micro displacement and the applied axial force is nearly linear. Under the condition of 1 Hz in frequency, 500 N in loading force and 18,000 reciprocating cycles, the bone fixator can still be in good condition, which proves the feasibility of the design.Originality/valueBiomechanical properties of bones and fixators are studied by researchers. However, few simulate a real force environment and combine forces in different directions. So a novel system is designed and fabricated to evaluate the biomechanical properties of the bones and fixators. Results of the experiments show that this new system is reliable and stable, which can support the biomechanical study and clinical treatment.

Вплив гасел на поведінку людини як засіб маніпулювання свідомістю

This article studies the new methods of impact on human consciousness and those that occurred in the history of Ukraine in the period from 1917 to 1920. Those methods were applied to manipulate the behavior of individuals in order to achieve the manipulators’ objectives. The issue is becoming more and more relevant in terms of developed information societies and is an essential component of information security. The mentioned analysis allows to study the situation in this field in depth, to learn about the consequences of certain social phenomena that allows to develop the measures to prevent mass manipulation. The relevance of the research is that communication is an important tool for achieving a certain goal in the information sphere, primarily because of their strong influence on public consciousness and, consequently, the effective and expansive formation of certain models of behavior of a huge number of individuals. Human consciousness becomes the object of manipulating by both internal political forces of different directions and external information influences, which is quite relevant during the period of information wars. The objective of the study is to reveal the influence of slogans on the behavior of wider population at the beginning of the last century (during 1917-1920 of the twentieth century), when seemingly incredible and phantasmagoric Bolshevik slogans drastically influenced the fate of millions of Ukrainians and determined the future of Ukraine for many years to come. That is when the expansive formation and dissemination of ideas without proper reflection led to irreversible and tragic historical consequences.In the proposed work, the effect of slogans on the behavior of people is examined through the prism of influence of printed periodicals, the most widespread in the early twentieth century, and the most effective in terms of providing information to the widest range of readers of the media.

Influence of End Structure on Electromagnetic Forces on End Winding of a 1550 MW Nuclear Generator

A 3D electromagnetic model of the end region of a 1550 MW nuclear generator is set up. The electromagnetic forces on the involute and nose parts of the end winding under a rated operation are obtained through the 3D time-step finite element method. The electromagnetic forces on different coils in the same phase are analyzed. By changing the rotor’s relative length and stator coil’s linear length in the 3D electromagnetic model, the electromagnetic force distributions on the end winding are obtained. The influence of each structure change on the electromagnetic force in different directions is studied in detail. Conclusions that can be helpful in decreasing the electromagnetic forces on the end winding through optimizing the end region design are presented.

Dialogue System for Fostering Way of Thinking Based on Physical Theory in Dynamics

Thinking based on physical theory is crucial for understanding physics. Dynamics is the initial physical theory that Japanese students learn in high school physics. In the theory of dynamics, the motion of objects is explained as a resultant of two forces of different directions. If students are not able to grasp the motion of objects by a resultant of two forces, they will not understand dynamics in physics at all. To extend such a way of thinking, we developed a dialogue system that encourages students to approach the motion of objects from the viewpoint of forces by asking them to explain the differences of the motion of the objects in a picture based on the similarity of their forces. Our system gives hints to guide them to reach correct answers. The results of our evaluation experiment suggest that the system is effective for observing the motion of objects by the two forces of vertical and horizontal directions.

The integrin-talin complex under force.

Integrins are the major transmembrane cellular adhesion receptors. Talin binds to integrins with its head domain and links them to the actin cytoskeleton with its rod domain, acting as the force linkage between the extracellular matrix and the cytoskeleton. It is unknown how forces in different directions affect the integrin-talin complex. We show that small forces applied to the integrin-talin complex breaks a salt bridge between the integrins α- and β-subunit, unlocking the integrin from its resting state. Forces parallel to the membrane lead to a zipper-like unbinding. Forces normal to the membrane induce strengthening of the complex. Our results indicate that the integrin-talin complex is physiologically optimized to be strengthened by applied forces at certain locations within the cell.

Investigation on cornering brake stability of a heavy-duty vehicle based on a nonlinear three-directional coupled model

A nonlinear three-directional coupled lumped parameters (TCLP) model is proposed for a heavy-duty vehicle to investigate the longitudinal, lateral and vertical dynamics of vehicles simultaneously. The nonlinear property of suspension damping is described by a fitted exponent model from experimental data. The nonlinear tire forces in different directions are modeled by the nonlinear Gim model and the vertical single dot contact model with square nonlinearity. The system responses are calculated by numerical integration and compared with the Functional Virtual Prototyping (FVP) model and the test data, so as to verify the validity of this new vehicle model. With Lateral-Load Transfer Ratio (LTR) and yaw rate as evaluation indexes, the influences of system parameters on cornering brake stability are analyzed. The critical vehicle speed table is also obtained. The study shows that high vehicle running speed, large front wheel steering angle, large tire cornering stiffness or small braking moment is harmful to yaw stability and roll stability. Road surface frictional coefficient mainly influences yaw stability, and vertical tire stiffness and road surface roughness mainly influence roll stability.

Differences Between Types Of Constant Resistance On Torque And Muscle Activation During Elbow Flexion Exercise

Constant resistance is the most common method to enhance strength. Constant resistance load is always the same across the full range of movement. However, pulleys can generate forces in different directions (x and y axis) while free-weights only generate force in one direction (y axis). PURPOSE: To investigate torque and muscle activation between elbow flexion exercise performed with free-weights and pulleys. METHODS: Five resistance trained males (body mass: 73.43±17.32 kg; height: 176.03 ±12.73 cm) and two females (body mass: 53.9±6.79 kg; height: 163.75 ±8.84 cm) participated. Maximal voluntary isometric contraction of the elbow flexors was measured at 90° of flexion for 5 seconds. Subjects performed 10 unilateral elbow flexions using free-weights and pulleys with 40% of their maximal isometric contraction load. Exercises were performed in a randomized order and at a pre-established rhythm of 2 seconds for each dynamic action controlled by a metronome. Ten minutes of rest between protocols was given. Surface electromyography of the biceps brachii was collected at 2400 Hz and synchronized with two-dimensional sagittal plane video at 60 Hz. Anatomical markers on the upper-limb and an electrogoniometer were used. During the pulley exercise, a load cell was used to record force. Five repetitions were analyzed. Root mean square (RMS) and mean sum of torques (MST) were calculated with a specific routine written in Matlab. Paired t-tests were used to determine significant (p≤0.05) differences between exercises. RESULTS: For the load used, there was no significant difference between pulley and free-weight. Similarly, there was no significant difference between pulley and free-weight for RMS (free-weight: 0.025 ± 0.006 mV; pulley: 0.026 ± 0.005 mV). However, MST was significantly greater for pulley (3,942.9 ± 1,013.7 N.m) than for free-weight (2,604.3 ± 705.6 N.m). CONCLUSION: The use of a pulley during elbow flexion exercise produced greater torque when compared with free-weight. However, biceps brachii activation was not different. More studies are necessary to investigate muscle activation in other muscles performed with different types of constant resistance.

Actively controlled fibrillar friction surfaces

In this letter, we propose a technique by which we can actively adjust frictional properties of elastic fibrillar structures in different directions. Using a mesh attached to a two degree-of-freedom linear stage, we controlled the active length and the tilt angle of fibers, independently. Thus, we were able to achieve desired levels of friction forces in different directions and significantly improve passive friction anisotropies observed in the same fiber arrays. The proposed technique would allow us to readily control the friction anisotropy and the friction magnitude of fibrillar structures in any planar direction.

Mechanism of kaolinite sheets curling via the intercalation and delamination process

Kaolinite naturally occurs in the plate form for the interlayer hydrogen bond and the distortion and adaption of tetrahedron and octahedron. But kaolinite sheets can be exfoliated to nanoscrolls artificially in laboratory through multiple-step displacement intercalation. The driving force for kaolinite sheet to be curled nanoscroll originates from the size discrepancy of Si–O tetrahedron and Al–O octahedron. The displacement intercalation promoted the platy kaolinite sheets spontaneously to be scrolled by eliminating the interlayer hydrogen bond and atomic interaction. Kaolinite nanoscrolls are hollow tubes with outer face of tetrahedral sheet and inner face of octahedral sheet. Based on the theoretical calculation it is firstly reported that the minimum interior diameter for a single kaolinite sheet to be scrolled is about 9.08nm, and the optimal 24.30nm, the maximum 100nm, which is verified by the observation of scanning electron microscope and transmission electron microscope. The different adaption types and discrepancy degree between tetrahedron and octahedron generate various curling forces in different directions. The nanoscroll axes prefer the directions as [100], [11¯0], [110], [31¯0], and the relative curling force are as follows, [31¯0]>[100]=[11¯0]>[110].

Free and forced vibration analysis of coupled conical–cylindrical shells with arbitrary boundary conditions

This paper presents a free and forced vibration analysis of coupled conical–cylindrical shells with arbitrary boundary conditions using a modified Fourier–Ritz method. Under the current framework, regardless of the boundary conditions, each of the displacement components of both the conical and cylindrical shells are expanded invariantly as a modified Fourier series, which is composed of a standard Fourier series and closed-form supplementary functions introduced to accelerate the convergence of the series expansion and remove all the relevant discontinuities at the boundaries and the junction between the two shell components. All the expansion coefficients are determined by using the Rayleigh–Ritz method as the generalized coordinates. By using the present method, a unified solution for the coupled conical–cylindrical shells with classical and non-classical boundary conditions can be directly derived without the need of changing either the equations of motion or the expressions of the displacements. The reliability and accuracy of the present method are validated by comparison with FEM results and those from the literature. Studies on the effects of dimensional and elastic restraint parameters on the free vibrations are also reported. Investigation on vibration of the conical–cylindrical–conical shell combination shows the extensive applicability of present method for more complex shell combinations. New numerical examples are also conducted to illustrate the forced vibration behavior of the coupled conical–cylindrical shell subjected to the excitation forces in different directions.

Numerical Study of the Zinc Oxide Nanowire Geometry Effect on Nanogenerator Output

Piezoelectric nanogenerator (NG) made of nanowires (NWs) is a suitable device for harvesting ambient mechanical energy, applicable for self-powered electronic systems and nanodevices that operate at low power. The coupled piezoelectric and semiconducting characteristics of the zinc oxide (ZnO) NW cause an output voltage generation that made it interesting to use as an energy harvesting device in nanoscale. In this paper, the piezoelectric potential distribution in a bent ZnO NW is investigated, numerically. To do this, a three-dimensional finite element simulation of the device is performed and the results are analyzed and discussed. It is found that the output piezoelectric potential, for a constant nanowire length, is decreased as the diameter of ZnO NW increases. Study on the effect of NW diameters shows the potential will remain constant for nanowire with aspect ratio below 15. Further, the NWs are considered with an inclination of 20 degree relative to the substrate to study by applying force in different directions. The latter indicates an improvement on the output piezoelectric potential. The obtained results show that the ZnO NW can be used as a good energy harvester device by considering a suitable diameter, length and with a justified inclination angle.

Experimental Investigations on Characteristics and Welding Forces in Friction Stir Welding of AA 6061-T6 Aluminum Alloy

Friction stir welding (FSW) technology requires a meticulous understanding of the process and consequent mechanical properties of the welds in order to be used in the production of high performance components. This paper deals with an experimental campaign aimed at the evaluation of the mechanical properties of AA6061-T6 friction stir welded joints. The joints are obtained by varying the welding parameters, namely, tool rotating speed and feed rate. The non-threaded tool is made of hot work die steel H13. The quality of the joints is evaluated in terms of both hardness and tensile strength. Moreover, for going a step further to study and control welding heat input in FSW process, a piezoelectric load cell is installed between the fixture table and the machine tool workbench in order to measure the welding forces in different directions.

Bolt from the blue: Basal ganglion bleed following lightning strike

Dear Sir, Injuries secondary to lightning strike are fortunately rare. Nervous system is commonly involved.[1] Cerebral hemorrhage following lightning injuries has been described and is, for unknown reasons, usually seen in the basal ganglia.[2–5] We report a case of young male presenting with basal ganglia bleed following lightning injury. A 17-year-old male was struck by lightning while working in the field. He was found unconscious by his co-workers. He was hospitalized within an hour. Examination revealed left corneal ulceration (entry wound) and superficial burn injury over the right side of neck (exit wound). The electrocardiogram was normal. Neurologically, he was not responding to commands and was localizing to painful stimulus with the right upper limb. He had left hemiplegia. Computed tomography (CT) scan of head showed bleed with multiple layers in the right lentiform nucleus with mass effect [Figure 1a]. There was no coagulation abnormality detected. CT angiogram showed no abnormality in the neck and major intracranial vessels. There was no extravasation of dye. In view of the mass effect and poor neurological status, he underwent large decompressive craniectomy and evacuation of hematoma [Figure 1b]. He received intensive care and improved in sensorium. Gradually, the weakness improved. Figure 1 (a) Pre-op Non-contrast computed tomography (NCCT) head showing right lentiform nucleus hematoma with mass effect following lightning strike. (b) Post-op NCCT head showing adequate decompression and evacuation of hematoma Lightning injuries to central nervous system are second only to acute cardiovascular injuries as the principal cause of death. Neurologic complications after lightning consist of: 1) immediate and transient variety presenting with the symptomatology which includes loss of consciousness, amnesia, confusion, headache, paresthesia, and weakness; 2) immediate and prolonged or permanent variety which includes post-hypoxic-ischemic encephalopathy, intracranial hemorrhages, cerebral infarction and cerebellar syndromes; 3) delayed presentation after weeks to months including motor system disease and movement disorders and 4) destructive injuries secondary to falls.[1] The mechanisms of neurological injuries include thermal effects, electrical effects, induced electrical currents, blast effects, and injuries related to falls. Lightning's electrical current is enormous, even though of brief duration, and causes immense thermal injury to tissues. Electric fields can damage the structural integrity of the lipid bilayer present in membrane of nerve and muscle tissues, termed as electroporation. The intense heating of the air surrounding the lightning flash can generate an explosive thunderous blast causing barotraumas.[1] Intracranial hemorrhages in lightning-strike patients often appear in basal ganglia.[2–5] Blunt head trauma and acute hypertension secondary to intense peripheral vasoconstriction as a cause are unlikely as they rarely cause basal ganglia bleed.[2] Studies in sheep suggest that current may enter via orifices (eyes, nose, ears) and travel caudally from neocortex toward the basal ganglia and brainstem.[1] Blood vessels and neural tissue have been found to carry more current per unit area than the other tissues and to become damaged before the surrounding tissues, in an animal model. Preferential conduction along Virchow-Robin spaces in the anterior perforated substance has been a proposed mechanism of bleed after a lightning strike.[3] However, this mechanism does not explain the predilection for basal ganglia. Blood vessels in this region are almost perpendicular to the parent vessels and there is gross disparity in sizes. Thus, the current passing through these vessels would also be disproportionate and in opposite directions. The electromagnetic fields produced by the passing currents in these vessels exert forces in different directions, possibly leading to shearing of the smaller vessels from parent arteries. Most victims of lightning who have not had a cardiac arrest will survive. Most of these patients are young, and with aggressive management, these patients survive to have a productive life.