Motor Force Research Articles

Rappers as hip-hopers: the remaking of authenticity and construction of the future by Korean underground rappers

ABSTRACT Contemporary Korean hip-hop has made its way into the mainstream of youth culture, and Korea’s hip-hop scene has emerged as a significant social space in which the voices of the young generation resonate vividly. When compared with the rest of their cohort, emblematized as the so-called ‘Give-up Generation’, the optimism of rappers provides a fascinating subject for exploration. In order to answer the question of why young Korean rappers profess their dreams in the age of no-hope, we interviewed six underground rappers, delving particularly into the following two themes. First is the inquiry into the rappers’ logic of hip-hop practices, under the conceptual rubric of ‘remaking authenticity’. We found that by inventing their own figurative ghettos and symbolically becoming black, they actively reinvent Korean hip-hop authenticity. Second is the inquiry into the principle of their practices. Our findings show that the fundamental motor force which drives them consists of their aspiration for a better future. The dreams of these rappers derive from three distinct sources. The first source is the illusio (Bourdieu) of the Korean hip-hop field; the second source is the musical form of hip-hop itself; the final source is the communities of dreamers to which the rappers belong.

Efisiensi Motor Sinkron Linier dengan Magnet Permanen Sebagai Penggerak KRL Terbaru

The latest electric train at this time has begun to be widely used linear synchronous motors with permanent magnets as driving locomotives. This permanent magnet has the same function as a conventional synchronous motor which is to produce a magnetic field so that the motor can move linearly. This linear synchronous motor does not have a gear (gear) and axis, but the mechanical motion of this linear motor is synchronous with the magnetic field running. This running magnetic field is produced by the entanglement of the three phases and the arrangement of magnetic poles U, S, U, S. Because the motor is linear synchronous is a high-speed motor, the mechanical speed is the same as the speed of the magnetic field running. So that this motor is capable of producing large thrust compared to the use of conventional motors (DC motors and induction motors) to drive electric rail trains. If the conventional synchronous motor uses a frequency of 50 Hz, then the linear high-speed synchronous motor uses a frequency of 5-50 Hz in changing its speed and this research the efficiency, electromagnetic power (thrust) and thrust force of a synchronous motor will be analyzed. linear according to the frequency selection from 5-50 Hz, to drive the electric train locomotive.

Excitability of Upper Layer Circuits Relates to Torque Output in Humans.

The relation between primary motor cortex (M1) activity and (muscular) force output has been studied extensively. Results from previous studies indicate that activity of a part of yet unidentified neurons in M1 are positively correlated with increased force levels. One considerable candidate causing this positive correlation could be circuits at supragranular layers. Here we tested this hypothesis and used the combination of H-reflexes with transcranial magnetic stimulation (TMS) to investigate laminar associations with force output in human subjects. Excitability of different M1 circuits were probed at movement onset and at peak torque while participants performed auxotonic contractions of the wrist with different torque levels. Only at peak torque we found a significant positive correlation between excitability of M1 circuits most likely involving neurons at supragranular layers and joint torque level. We argue that this finding may relate to the special role of upper layer circuits in integrating (force-related) afferent feedback and their connectivity with task-relevant pyramidal and also extrapyramidal pathways projecting to motoneurones in the spinal cord.

Design and Experimental Verification of a High Force Density Tubular Permanent Magnet Linear Motor for Aerospace Application

<div class="section abstract"><div class="htmlview paragraph">This paper presents the design and construction of a high force density tubular permanent-magnet (PM) linear motor. A strut structure of a tubular PM linear motor developed to improve resistance to impurities and structural rigidity is described.</div><div class="htmlview paragraph">In the design, computationally efficient two-dimensional finite-element analysis is used to estimate the motor force density. The motor’s design is optimized for the major pole number/slot number combinations of 8/24, 16/24, 20/24, 28/24, 32/24, and 40/24. The optimized motor design of a three-phase 16/24 combination with one-layer winding achieved the highest force-to-mass density. The force-to-mass density of the designed motor is higher than that of the first prototype motor by a factor of 5. The validity of the proposed design method and the expected drive characteristics are experimentally verified using the prototype.</div></div>

Reduction of sixth‐order radial force by harmonic current control and its application to EPS motors

AbstractTo improve noise and vibration of Electric Power Steering (EPS) system, we focus on the reduction of the sixth‐order radial force of an EPS motor by regulating its harmonic current. Because an EPS system is operated in a wide speed range, a reduction method is required to work even for dynamic motor speed. In this article, we introduce our method and report its test result to show the reduction of sixth‐order radial vibration of an EPS motor.

Detent Force, Thrust, and Normal Force of the Short-Primary Double-Sided Permanent Magnet Linear Synchronous Motor With Slot-Shift Structure

Phase-shift or pole-shift method can reduce the detent force of the double-sided permanent magnet linear synchronous motor (DS-PMLSM) dramatically. However, this method causes a decrease in thrust and an increase in normal force simultaneously. To overcome this drawback, a novel slot-shift structure whose slots on the two sides of the primary component are staggered by an optimal distance is proposed in this paper. The models of the detent force including the end force and cogging force is established theoretically, and then verified by finite element analysis. The windings in the upper primary and the lower primary are arranged differently to improve the average thrust. The thrust characteristics of the DS-PMLSM under different shifted distances are analyzed and compared in detail. Furthermore, the primary component employing two kinds of core laminations is proposed to reduce both the dc component and ripple of the normal force. Finally, a DS-PMLSM prototype is tested, and the experimental results are compared with the analytical results to verify the effectiveness of the theoretical and simulation research.

Analysis of Flux Linkage and Detent Force for a Modular Tubular Permanent Magnet Synchronous Linear Motor With Large Slots

Conventionally, for a tubular permanent magnet synchronous linear motor (TPMSLM), adopting a modular structure can effectively reduce the detent force; however, the thrust density is sacrificed via the large proportion of the flux barrier to the total primary component volume. To overcome this disadvantage, this paper proposes a novel modular TPMSLM, in which the unit primary component adopts the large slot structure containing several coils. Focusing on this motor, research on the flux linkage characteristic is performed to obtain the design principle, and then the detent force is analyzed and suppressed by reasonable design of end teeth. First, the flux linkage characteristics of the unit motor and the whole motor are investigated. Variation rule of the coil flux linkage affected by the end tooth is discussed, and the principle of realizing three-phase balance for the whole motor flux linkage is elaborated. Moreover, the principle of the detent force suppression is verified and the detent force is further suppressed through the end tooth design. Finally, a prototype is developed. The back electromotive force and the detent force were tested, which verified the effectiveness of the novel modular TPMSLM proposed.

Controlled emotional tactile stimulation during functional magnetic resonance imaging and electroencephalography

BackgroundTactile stimulation used to induce emotional responses is often not well-controlled. Replicating the same tactile stimulations across studies is difficult, compared to replicating visual and auditory modalities, which have standardized stimulus sets. Standardizing a stimulation method by replicating stimuli across studies is necessary to further elucidate emotional responses in neuroscience research using tactile stimulation. The new methodWe developed a tactile stimulation device. The device's ultrasonic motor and optical force sensor have the following criteria: (1) controls the physical property of stimuli, pressure, and stroking speed; (2) measures actual touch timing; (3) is safe to use in a magnetic resonance imaging (MRI) scanner; and (4) produces low noise in electroencephalography (EEG) and MRI. ResultsThe noise level of the device's drive was sufficiently low. For the EEG experiment, we successfully used signal processing to diminish the commercial power supply noise. For functional MRI (fMRI) scans, we found <5% signal loss occurred during device rotation. Comparison with existing method(s)We found no previous report about the noise level of a tactile stimulation device used to induce emotional responses during EEG and fMRI recordings. The signal loss rate was comparable with that of other robotic devices used in MRI scanners. Emotional feelings induced by this stimulation method were comparable with those elicited in other sensory modalities. ConclusionsThe developed device could be used for cognitive-affective neuroscience research when conducting EEG and fMRI scans. The device should aid in standardizing affective tactile stimulation for research in psychology and cognitive neuroscience.

Mesoscopic simulations of anisotropic chemically powered nanomotors.

Chemically powered self-propelled colloids generate a motor force by converting locally a source of energy into directed motion, a process that has been explored both in experiments and in computational models. The use of active colloids as building blocks for nanotechnology opens the doors to interesting applications, provided we understand the behavior of these elementary constituents. We build a consistent mesoscopic simulation model for self-propelled colloids of complex shape with the aim of resolving the coupling between their translational and rotational motion. Considering a passive L-shaped colloidal particle, we study its Brownian dynamics and locate its center of hydrodynamics, the tracking point at which translation and rotation decouple. The active L particle displays the same circling trajectories that have been found experimentally, a result which we compare with the Brownian dynamics model. We put forward the role of hydrodynamics by comparing our results with a fluid model in which the particles' velocities are reset randomly. There, the trajectories only display random orientations. We obtain these original simulation results without any parametrization of the algorithm, which makes it a useful method for the preliminary study of active colloids, prior to experimental work.

Analytical modelling of radial suspension force in bearingless surface‐mounted PM synchronous motors considering static rotor eccentricity

In this study, a new analytical model is provided in order to calculate the radial suspension force in bearingless surface-mounted permanent magnet synchronous motor with static rotor eccentricity. The proposed model is based on the harmonic analysis of magnetic flux density, and considers the influence of both radial and tangential air-gap field components on the computation of radial suspension force. This model can reveal the generation mechanism of the radial suspension force and identify the generation sources of the force ripples. Furthermore, the magnitudes and frequencies of radial suspension force harmonics, and the relationship between the radial suspension force and rotor eccentric displacements can be accurately predicted by the proposed model. However, this model cannot be used for saturated machines. The analytical model is verified by finite-element analyses and the result of static experimental study.

Research on Load Estimation for a PMLM Actuated Vibration Stage

This paper puts forward a new load estimation method in time domain for PMLM servo loop tuning. This method takes advantage of the symmetry of cogging force distribution and identifies the friction force in constant velocity phase. Experiments have been carried out on a PMLM actuated vibration stage to validate the method. It’s discovered that it’s better to take an average of two estimations as the true value with movement range by 0.25 pitch’s difference so that cogging effect could be eliminated. Moreover, movement range is better to be greater than 1 pitch. Motor force constant should be calibrated according to its actual output.

In Defense of Resistance

Resistance to unjust power and authority has long been the angry energy of everyday struggle, the defiant democratization of progressive social movements, and the motor force of progressive social change. As critical criminologists, then, our role is to defend the practice of resistance and to explore its radical potential. In doing so, we can usefully investigate emergent moments of resistance that transcend narrow notions of individual intentionality, and we can trace the intricate interplay between immediate acts of resistance and larger dynamics of social transformation. We can focus especially on forms of resistance that both reveal the operations of power and reverse those operations in the interest of social justice. Most importantly, we can move beyond the sort of faux-radical pessimism that denies the potential of contemporary resistance, and embrace instead a multitude of resistant possibilities.

When words hurt: Verbal suggestion prevails over conditioning in inducing the motor nocebo effect.

Perception and behavior are strongly influenced by the verbal information conveyed by other individuals (e.g., verbal suggestion) and by learning (e.g., conditioning). This influence is well represented by the placebo and nocebo effects, in which positive verbal suggestion associated with positive conditioning induces beneficial outcomes (placebo effect), while the opposite is true for the negative counterpart (nocebo effect). It is still unclear whether verbal suggestion and conditioning exert distinctive roles in influencing perception, behavior and motor system activity when they occur in opposite directions. To this purpose, fifty-three healthy volunteers were assigned to four groups characterized by either congruent or incongruent verbal suggestion and conditioning. Participants were asked to perform a force motor task by pressing a piston as strongly as possible. Transcranial magnetic stimulation over the primary motor cortex was used to record motor evoked potentials (MEP) and cortical silent period (CSP) from the muscle involved in the task. We found that negative verbal suggestion counteracted positive conditioning and induced sense of weakness, effort, and force decrements. MEP amplitude was stable, whereas the CSP duration shortened in all the groups throughout the procedure, indicating the involvement of cortical inhibitory circuits, independently of the type of verbal suggestion or conditioning. Our findings highlight a prevalent role of verbal suggestion over conditioning in determining a worsening (nocebo effect) but not an improvement (placebo effect) of motor performance. These results suggest that words associated with treatments should be chosen carefully to avoid negative outcomes, especially in sports and clinical settings.

Dense Dwarfs versus Gelatinous Giants: The Trade-Offs and Physiological Limits Determining the Body Plan of Planktonic Filter Feeders.

Most marine plankton have a high energy (carbon) density, but some are gelatinous with approximately 100 times more watery bodies. How do those distinctly different body plans emerge, and what are the trade-offs? We address this question by modeling the energy budget of planktonic filter feeders across life-forms, from micron-sized unicellular microbes such as choanoflagellates to centimeter-sized gelatinous tunicates such as salps. We find two equally successful strategies, one being small with high energy density (dense dwarf) and the other being large with low energy density (gelatinous giant). The constraint that forces large-but not small-filter feeders to be gelatinous is identified as a lower limit to the size-specific filter area, below which the energy costs lead to starvation. A further limit is found from the maximum size-specific motor force that restricts the access to optimum strategies. The quantified constraints are discussed in the context of other resource-acquisition strategies. We argue that interception feeding strategies can be accessed by large organisms only if they are gelatinous. On the other hand, organisms that use remote prey sensing do not need to be gelatinous, even if they are large.

The Influence of Force Level and Motor Unit Coherence on Nonlinear Surface EMG Features Examined Using Model Simulation.

Nonlinear features extracted from surface EMG signals have been previously used to infer information on coherent or synchronous activity in the underlying motor unit discharges. However, it has not yet been assessed how these features are affected by the density of the surface EMG signal, and whether changes in the level of muscle activation can influence the effective detection of correlated motor unit firing. To examine this, a motoneuron pool model receiving a beta-band modulated cortical input was used to generate correlated motor unit firing trains. These firing trains were convolved with motor unit action potentials generated from an anatomically accurate electrophysiological model of the first dorsal interosseous muscle. The sample entropy (SampEn) and percentage determinism (%DET) of recurrence quantification analysis were calculated from the composite surface EMG signals, for signals comprised of both correlated and uncorrelated motor unit firing trains. The results show that although both SampEn and %DET are influenced by motor unit coherence, they are differentially affected by muscle activation and motor unit distribution. The results also suggest that sample entropy may provide a more accurate assessment of the underlying motor unit coherence than percentage determinism, as it is less sensitive to factors unrelated to motor unit synchrony.

Magnetic Field Analysis and Flux Barrier Design for Modular Permanent Magnet Linear Synchronous Motor

Modularization design has been widely used to reduce the detent force of permanent magnet linear synchronous motor (PMLSM). For modular PMLSM, ideally, unit motors are independent of each other and the detent force of the whole motor is the sum of that for unit motors; thus, the whole motor's detent force can be suppressed by adjusting the phase difference among the unit motors’ detent forces. But actually, there is coupling effect between adjacent unit motors, which has adverse effect on the detent force suppression. The coupling effect changes the magnetic field distribution, which is often neglected in current research. Hence, this paper carries out the research on magnetic field analysis and flux barrier design for modular PMLSM considering the coupling effect: the influence of the coupling effect on the air gap magnetic field is clarified through magnetic field analysis; the coupling force is isolated by finite element analysis, and then the effects of key parameters are discussed; the whole motor's detent force model considering the coupling effect is established, and an optimal design method of adjusting the flux barrier length is presented to suppress the detent force. Finally, a prototype is made to test the detent force characteristics with different flux barrier lengths, which verifies the research theory in this paper. The research results in this paper can provide guidance and reference for the design of modular PMLSMs.

Harmonic Model and Remedy Strategy of Multiphase PM Motor Under Open-Circuit Fault

Modular multiphase (MMP) PM motors have the ability to work continuously under a faulty mode. However, ripples in the spin torque of the motor and unbalanced forces incur rotor vibrations in postfault operations, which seriously degrade the performance of the PM motors. This paper presents a computationally efficient method to derive harmonic models for characterizing the pulsating torque and unbalanced forces of an MMP-PM motor under an open-circuit fault, and the corresponding optimal solutions to its inverse current model to remedy the fault. The model formulation, current harmonic identification, and remedial strategy for suppressing torque ripples and unbalanced forces are illustrated with an MMP-PM motor under an open-circuit fault; both odd and even number of phases are considered. The effectiveness of the harmonic models and remedy strategies are numerically validated with two typical (5- and 6-phase) MMP-PM motors under a one-phase/open- circuit fault and evaluated experimentally on a custom-designed 6-phase duplex motor .

The Impact of Mental Fatigue on Force and Motor Unit Firing Variability in Young Adults

Mental fatigue leads to declines in performance of tasks such as cycling time trial performance and skill-based outcomes such as soccer shot accuracy. The neuromuscular mechanisms leading to these declines are not well understood. Although force variability has been shown to increase under dual-task conditions, it is not known if these results extend to conditions of mental fatigue. PURPOSE: The purpose of this study was to assess the impact of mental fatigue on variability in motor output in healthy, young individuals. Specifically, we sought to determine if a task that induces mental fatigue has effects on force and motor unit firing variability. METHODS: Nineteen participants (10 female, 9 male) performed 10-s isometric contractions at 20 and 50% maximum voluntary contraction (MVC) before, during, and after completing 20 min of the psychomotor vigilance task (PVT). The PVT is a sustained attention task that induces mental fatigue, as indicated by increases in reaction time (RT) to visual stimuli. Force and indwelling motor unit (MU) firings were measured prior to and immediately following performance of the PVT (single task), and within the first and final minutes of PVT performance (dual task). Subjective ratings of fatigue were also obtained using a 10-point Likert scale before and after the PVT. RESULTS: Reaction time increased by 14% from the beginning of the PVT (276.14 ± 31.54 ms) to the end (314.15 ± 37.74 ms, p<0.001). Subjects also subjectively reported greater levels of fatigue following the PVT (4.95 ± 1.84) compared to before (3.00 ± 1.20, p<0.001), indicating successful induction of mental fatigue. For the coefficient of variation (CV) of force there was no significant main effect of time (p=0.14) or contraction intensity (p=0.33), and no significant interaction (p=0.51). For the CV of the MU interspike interval there was a main effect of contraction intensity with a greater CV of the interspike interval during the 50% MVC (19.51 ± 3.84%) than the 20% MVC (14.87 ± 3.59%, p<0.001) contractions. However, there was no significant main effect of time (p=0.83) and no significant interaction (p=0.23). CONCLUSION: Inducing mental fatigue did not lead to changes in the variability of force production or motor unit firing during isometric contractions at 20 and 50% MVC as a single-task or during a concurrent cognitive task.

Bi-cephalic transcranial direct current stimulation combined with functional electrical stimulation for upper-limb stroke rehabilitation: A double-blind randomized controlled trial.

Stroke survivors often present poor upper-limb (UL) motor performance and reduced movement quality during reaching tasks. Transcranial direct current stimulation (tDCS) and functional electrical stimulation (FES) are widely used strategies for stroke rehabilitation. However, the effects of combining these two therapies to rehabilitate individuals with moderate and severe impairment after stroke are still unknown. Our primary aim was to evaluate the effects of concurrent bi-cephalic tDCS and FES on UL kinematic motor performance and movement quality of chronic post-stroke subjects with moderate and severe compromise. Our secondary aim was to verify the effects of combining these therapies on handgrip force and UL motor impairment. We randomized 30 individuals with moderate and severe chronic hemiparesis after stroke into tDCS plus FES (n=15) and sham tDCS plus FES (n=15) groups. Participants were treated 5 times a week for 2 weeks. Kinematic motor performance (movement cycle time, velocity profile) and movement quality (smoothness, trunk contribution, joint angles) were assessed during an UL reach-to-target task.Handgrip force and motor impairment were also recorded before and after the intervention. Participants allocated to the tDCS plus FES group improved movement cycle time (P=0.039), mean reaching velocity (P=0.022) and handgrip force (P=0.034). Both groups improved the mean returning phase velocity (P=0.018), trunk contribution (P=0.022), movement smoothness (P=0.001) and UL motor impairment (P=0.002). Concurrent bi-cephalic tDCS and FES slightly improved reaching motor performance and handgrip force of chronic post-stroke individuals with moderate and severe UL impairment. ClinicalTrials.gov (NCT02818608).

Thermodynamic Efficiency of Somatic Exocytosis of Serotonin.

Through somatic exocytosis neurons liberate immense amounts of transmitter molecules that modulate the functioning of the nervous system. A stream of action potentials triggers an ATP-dependent transport of transmitter-containing vesicles to the plasma membrane, that ends with a large-scale exocytosis. It is commonly assumed that biological processes use metabolic energy with a high thermodynamic efficiency, meaning that most energy generates work with minor dissipation. However, the intricate ultrastructure underlying the pathway for the vesicle flow necessary for somatic exocytosis challenges this possibility. To study this problem here we first applied thermodynamic theory to quantify the efficiency of somatic exocytosis of the vital transmitter serotonin. Then we correlated the efficiency to the ultrastructure of the transport pathway of the vesicles. Exocytosis was evoked in cultured Retzius neurons of the leech by trains of 10 impulses delivered at 20 Hz. The kinetics of exocytosis was quantified from the gradual fluorescence increase of FM1-43 dye as it became incorporated into vesicles that underwent their exo-endocytosis cycle. By fitting a model of the vesicle transport carried by motor forces to the kinetics of exocytosis, we calculated the thermodynamic efficiency of the ATP expenses per vesicle, as the power of the transport divided by total energy ideally produced by the hydrolysis of ATP during the process. The efficiency was remarkably low (0.1–6.4%) and the values formed a W-shape distribution with the transport distances of the vesicles. Electron micrographs and fluorescent staining of the actin cortex indicated that the slopes of the W chart could be explained by the interaction of vesicles with the actin cortex and the calcium-releasing endoplasmic reticulum. We showed that the application of thermodynamic theory permitted to predict aspects of the intracellular structure. Our results suggest that the distribution of subcellular structures that are essential for somatic exocytosis abates the thermodynamic efficiency of the transport by hampering vesicle mobilization. It is remarkable that the modulation of the nervous system occurs at the expenses of an efficient use of metabolic energy.