We propose a micro-flat ultrasonic motor that performs a high torque density by a tiny and flat stator for driving a miniature two-link. Such a two-link can be a fundamental technology that enables ...micro-assembling and micro-manipulation under a microscopic environment. In this paper, we build the micro-flat ultrasonic motor comprising of a flat stator with 2.6 mm in width and height and 1 mm in depth and evaluate the output performance measures. The prototype micromotor shows a torque of 55 µNm at a voltage of 80 V
by optimizing the preload between the stator and rotor. Moreover, a torque of approximately 100 µNm (10-g force generation by 1 mm radius) is obtained at higher voltages - this torque value is the largest in 2-3 mm scale motors reported to date. Two micro-flat ultrasonic motors drive a miniature two-link as direct-drive motors without gears. The motion of the two-link is demonstrated by an open-loop burst wave control, which is a pulse-width modulation control for an alternative voltage. Although the demonstration is simple, it shows the feasibility of the smallest and most practical link mechanism.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In order to study seismo-mechanochemical processes, two kinds of shock compression experiments – the recovery and the in-situ VISAR (velocity interferometer system for any reflector) experiments – ...were performed, using a single crystal of forsteritic olivine and a single-stage powder propellant gun. The generated peak shock pressures were 31.1 GPa for both the recovery and the VISAR experiments. Many shear planes were generated in the olivine crystal. The VISAR experiment revealed detailed time profiles for the particle and shock wave velocities during the compression and yielded the Hugoniot elastic limit (HEL) of the olivine to be 7.44 GPa. We observed, in one recovered sample, a clear local melting occurring along a shear plane. The microstructural observations of the shear plane and its walls using a field-emission scanning electron microscopy (SEM) and an analytical transmission electron microscopy (ATEM) revealed that plastically-deformed olivine was pulverized into a few hundred-nanometer size particle assemblages within a few-micrometers narrow zone along the shear plane and, locally have partially melted. Moreover, injection veins filled with olivine melt were found in the wall of the same shear plane. It was shown from the estimate of the critical resolved shear stress (CRSS) along the shear planes and the inferred slip velocity using the Hugoniot elastic limit (HEL) data that the power generated by the friction was large enough for melting to occur in the olivine. The whole process occurred in a time scale <0.6 microsecond. Pulverization (comminution) before melting is considered to be a common phenomenon in the formation of pseudotachylytes and in dynamically expanding seismic faults upon earthquakes.
Display omitted
•Shock compression experiments were performed using a forsterite single crystal and a powder propellant gun.•Particle velocity profile on the olivine surface was obtained by laser in situ measurement.•Many shear bands were generated in the olivine, where a clear local melting was observed.•It was found out that plastic deformation and pulverization took place before melting.•Pulverization before melting may be a common phenomenon in co-seismic faults in earthquakes.
We report on precision spectroscopy of subwavelength confined molecular gases. This was obtained by rovibrational selective reflection of NH3 and SF6 gases using a quantum cascade laser at λ ≈ 10.6 μ ...m . Our technique probes molecules at micrometric distances (≈ λ/2π) from the window of a macroscopic cell with submegahertz resolution, allowing molecule-surface interaction spectroscopy. We exploit the linearity and high resolution of our technique to gain novel spectroscopic information on the SF6 greenhouse gas, useful for enriching molecular databases. The natural extension of our work to thin cells will allow compact frequency references and improved measurements of the Casimir-Polder interaction with molecules.
Background
Decreased Gamma‐aminobutyric acid (GABA)‐ergic phasic inhibitory transmission in the spinal cord is thought to be responsible for the development of neuropathic pain. However, the role of ...GABAergic tonic current in substantia gelatinosa (SG) neurons in neuropathic pain remains to be fully elucidated. In this study, we assessed GABAergic tonic currents of SG neurons in a sciatic nerve chronic constriction injury (CCI) mouse.
Method
Whole‐cell patch clamp recordings form lumbar spinal cord slices was performed to evaluate GABAergic currents. We also investigated the expression changes of GABAA receptor subunits which are considered to mediate tonic currents.
Results
The percentage of SG neurons receiving GABAergic tonic currents decreased in CCI mice compared with Naïve mice. No significant change was observed in the mean amplitude of GABAergic tonic currents. RT‐PCR and Western blot revealed that the expression of GABAA receptor δ subunits decreased following CCI.
Conclusion
A reduction in the expression the δ subunit of the GABAA receptor and diminished GABAergic tonic current in SG neurons were observed after CCI in mice. GABAergic tonic current plays a key role in neuropathic pain. The GABAA receptor δ subunit may be a therapeutic target in neuropathic pain.
What does this study add?
In spinal SG neurons, GABAergic inhibitory transmission operates through both phasic and tonic currents, but physiological role is largely unknown. In this study, we report dysregulation of GABAA receptor δ subunit‐mediated tonic current in SG neurons may result in spinal disinhibition resulting in neuropathic pain in CCI mice.
Objectives. Following lesions in somatosensory pathways, deafferentation pain often occurs. Patients report that the pain is qualitatively complex, and its treatment can be difficult. Mirror visual ...feedback (MVF) treatment can improve deafferentation pain. We sought to classify the qualities of the pain in order to examine whether the potential analgesic effect of MVF depends on these qualities. Methods. Twenty-two patients with phantom limb pain, or pain related to spinal cord or nerve injury, performed a single MVF procedure. Before and after the MVF procedure, we evaluated phantom limb awareness, movement representation of the phantom or affected/paralysed limb, pain intensity on an 11-point numerical rating scale (0–10) and the qualities of the pain skin surface-mediated (superficial pain) vs deep tissue-mediated (deep pain) using lists of pain descriptors for each of the two categories. Results. Fifteen of the patients perceived the willed visuomotor imagery of the phantom or affected/paralysed limb after the MVF procedure. In most of the patients, a reduction in pain intensity and a decrease in the reporting of deep-pain descriptors were linked to the emergence of willed visuomotor imagery. Conclusions. In this pilot study, we roughly classified the pain descriptor items into two types for evaluating the qualities of deafferentation pain. We found that visually induced motor imagery by MVF was more effective for reducing deep pain than superficial pain. This suggests that the analgesic effect of MVF treatment does depend on the qualities of the pain. Further research will be required to confirm that this effect is a specific consequence of MVF.
Materials at high pressures and temperatures are of great current interest for warm dense matter physics, planetary sciences, and inertial fusion energy research. Shock-compression equation-of-state ...data and optical reflectivities of the fluid dense oxide, Gd3Ga5O12 (GGG), were measured at extremely high pressures up to 2.6 TPa (26 Mbar) generated by high-power laser irradiation and magnetically-driven hypervelocity impacts. Above 0.75 TPa, the GGG Hugoniot data approach/reach a universal linear line of fluid metals, and the optical reflectivity most likely reaches a constant value indicating that GGG undergoes a crossover from fluid semiconductor to poor metal with minimum metallic conductivity (MMC). These results suggest that most fluid compounds, e.g., strong planetary oxides, reach a common state on the universal Hugoniot of fluid metals (UHFM) with MMC at sufficiently extreme pressures and temperatures. The systematic behaviors of warm dense fluid would be useful benchmarks for developing theoretical equation-of-state and transport models in the warm dense matter regime in determining computational predictions.
Rotary-linear piezoelectric actuator using a single stator Mashimo, T.; Toyama, S.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control,
2009-January, 2009, 2009-Jan, 2009-01-00, 20090101, Letnik:
56, Številka:
1
Journal Article
Recenzirano
We report a piezoelectric actuator having a single stator with rotary and linear motions (RLPA). The stator is fabricated as a single metallic cube with a through-hole. The surface of the inner ...circle of the hole generates elliptical motions at each natural frequency, transferring the energy to an output shaft, when AC voltages at the appropriate resonant frequency are applied to the piezoelectric elements. This study clarifies the principle of rotary and linear motions and uses finite element methods (FEM) to show how the elliptical motions are generated. Modal analysis illustrated the shapes of the vibration modes and the natural frequencies, and the shape of the stator was designed accordingly. A dynamic analysis of the stator showed the generation of elliptical motion in the directions of the rotary and linear motions. The prototype RLPA was successfully actuated at the resonant frequencies, consistent with the dynamic analysis. The speed of the rotary and linear motions was obtained.
The human visual and somatosensory systems are interdependent. Using a visual subjective body-midline (SM) judgment task, we previously confirmed that pathologic pain and deafferentation can modify ...visuospatial perception, indicating that altered somatosensory experience can modify visual perception. Conversely, in the present study we investigated whether a change in visual experience can modify perception of pathologic pain.
We used prism adaptation (PA) to modify subjects' visual experience. Five patients with complex regional pain syndrome (CRPS) adapted to wedge prisms, producing a 20-degree visual displacement toward the unaffected side. Further, we used several types of prisms in a longitudinal single-case study. Wearing prismatic goggles, the subjects performed a target-pointing task once a day for 2 weeks. We evaluated pain intensity and visual SM judgment to measure the adaptive aftereffects at three time points: before PA (pre-test), immediately after the first PA exposure (IA-test), and after a 14-day sequence of PA exposure (post-test).
PA toward the unaffected side alleviated pathologic pain and other CRPS pathologic features, when measured at post-test. None of the IA-test results showed an analgesic effect. In the longitudinal study, sham PA and 5-degree PA did not produce any effects, and PA toward the affected side actually exacerbated the subjective pain.
Our findings suggest that vision can influence pathologic pain, and preliminarily suggest that prism adaptation has a direction-specific and reproducible effect on not only pathologic pain but also other CRPS pathologic features. Thus, prism adaptation may be a viable cognitive treatment for CRPS.
We present a mechanical design and implementation of spherical ultrasonic motor (SUSM) that is an actuator with multiple rotational degrees of freedom (multi-DOF). The motor is constructed of 3 ...annular stators and a spherical rotor and is much smaller and simpler than conventional multi-DOF mechanisms such as gimbals using servomotors. We designed a novel SUSM using experimental data from a single annular stator and a finite element method. The SUSM using a spherical rotor of diameter 20 mm without any reduction gear has demonstrated advantages of high responsiveness, good accuracy, and high torque at low speed. The dynamic implementation of SUSM was consistent with the driving model of SUSM based on a friction drive.
Spatial perception is achieved by integrating multisensory information. Using visual subjective body midline (vSM) judgments in patients with unilateral limb pain (complex regional pain syndrome ...CRPS), we found that their vSM deviated toward the affected side; however, deafferentation of the affected limb caused a transient pain decrease and a transient shift of the vSM deviation toward the unaffected side. Our results indicate that the persistent pain state in CRPS distorts visuospatial perception.
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