scholarly journals Coherent oscillations of a levitated birefringent microsphere in vacuum driven by nonconservative rotation-translation coupling

2020 ◽  
Vol 6 (23) ◽  
pp. eaaz9858 ◽  
Author(s):  
Yoshihiko Arita ◽  
Stephen H. Simpson ◽  
Pavel Zemánek ◽  
Kishan Dholakia
Keyword(s):  
Degrees Of Freedom ◽  
Detailed Balance ◽  
Optical Trap ◽  
Underlying Mechanism ◽  
Thermal Fluctuations ◽  
Mechanical Quality Factor ◽  
Mechanical Quality ◽  
Linearly Polarized ◽  
Translation Coupling ◽  
Equipartition Of Energy

We demonstrate an effect whereby stochastic, thermal fluctuations combine with nonconservative optical forces to break detailed balance and produce increasingly coherent, apparently deterministic motion for a vacuum-trapped particle. The particle is birefringent and held in a linearly polarized Gaussian optical trap. It undergoes oscillations that grow rapidly in amplitude as the air pressure is reduced, seemingly in contradiction to the equipartition of energy. This behavior is reproduced in direct simulations and captured in a simplified analytical model, showing that the underlying mechanism involves nonsymmetric coupling between rotational and translational degrees of freedom. When parametrically driven, these self-sustained oscillators exhibit an ultranarrow linewidth of 2.2 μHz and an ultrahigh mechanical quality factor in excess of 2 × 108 at room temperature. Last, nonequilibrium motion is seen to be a generic feature of optical vacuum traps, arising for any system with symmetry lower than that of a perfect isotropic microsphere in a Gaussian trap.

scholarly journals Mechanical Quality Factor of Pb(ZrxTi 1−x) 1−y (Mg1/3Nb2/3)yO3 Solid Solution Prepared by Wet-Dry Combination Method

1999 ◽  
Vol 67 (10) ◽  
pp. 985-987
Author(s):  
Yoshiyuki ABE ◽  
Taisyu YANAGISAWA ◽  
Kazuyuki KAKEGAWA ◽  
Yoshinori SASAKI
Keyword(s):  
Solid Solution ◽  
Quality Factor ◽  
Mechanical Quality Factor ◽  
Combination Method ◽  
Mechanical Quality

Piezoelectric Properties of PZT-5 Fiber/Epoxy Resin 1-3 Composites

2011 ◽  
Vol 239-242 ◽  
pp. 486-489
Author(s):  
Ling Fang Xu ◽  
Wen Chen ◽  
Jing Zhou ◽  
Chang Ping Yang
Keyword(s):  
Epoxy Resin ◽  
Coupling Coefficient ◽  
Piezoelectric Properties ◽  
Volume Fraction ◽  
Mechanical Quality Factor ◽  
Casting Method ◽  
Anisotropic Property ◽  
Niobium Doped ◽  
Mechanical Quality ◽  
Method Effects

Niobium doped Pb(Zr,Ti)O3fiber/epoxy resin 1-3 composites with different ceramic volume fraction of 10-85% were fabricated by filling-casting method. Effects of ceramic volume fraction on electric properties were investigated. For a typical 30% ceramic content composite, the thickness coupling coefficientkt, mechanical quality factorQm, acoustic impedanceZmand anisotropic propertykt/kpwere 0.67, 0.55, 11.03 MRayl and 2.23, respectively.

THE SCIENCE OF CONFINEMENT AND THE GLUEX/HALL D PROJECT AT JEFFERSON LAB

2003 ◽  
Vol 18 (03) ◽  
pp. 397-404 ◽  
Author(s):  
Alex R. Dzierba
Keyword(s):  
Degrees Of Freedom ◽  
Meson Production ◽  
First Year ◽  
Jefferson Lab ◽  
Coherent Bremsstrahlung ◽  
Linearly Polarized ◽  
Quantitative Understanding ◽  
Current Maximum ◽  
Photo Production ◽  
Photoproduction Data

One of the outstanding and fundamental questions in physics is the quantitative understanding of the confinement of quarks and gluons in quantum chromodynamics (QCD). Confinement is a unique feature of QCD. Exotic hybrid mesons manifest gluonic degrees of freedom and their spectroscopy will provide the crucial data needed to test assumptions in lattice QCD and phenomenology leading to confinement. Photo-production is expected to be particularly effective in producing exotic hybrids but data using photon probes are sparse. At Jefferson Lab, plans are underway to use the coherent bremsstrahlung technique to produce a linearly polarized photon beam. A solenoid-based hermetic detector will be used to collected data on meson production and decays with statistics that will exceed the current photoproduction data in hand by several orders of magnitude after the first year of running. In order to reach the ideal photon energy of 9 GeV/c for this mapping of the exotic spectra, the energy of the Jefferson Lab electron accelerator, CEBAF, will be doubled from its current maximum of 6 GeV to 12 GeV. The physics and project are described.

Workspace of a Gimbal With Joint Limits

1996 ◽  
Author(s):  
Har-Jou Yeh ◽  
Karim A. Abdel-Malek
Keyword(s):  
Degrees Of Freedom ◽  
Spherical Surface ◽  
Perturbation Technique ◽  
Underlying Mechanism ◽  
Singular Curve ◽  
Constraint Function ◽  
Rank Deficiency ◽  
Analytical Criterion ◽  
Joint Limits ◽  
Three Degrees Of Freedom

Abstract An analytical formulation for determining the workspace of a point on a body suspended in a Gimbal mechanism is presented. Although the gimbal mechanism comprises three degrees of freedom, the resulting workspace is a region on a spherical surface. The constraint function of the underlying mechanism is studied for singularities using a row-rank deficiency condition of its constraint Jacobian. Singular curves on the resultant spherical surface are determined by a similar analytical criterion imposed on the system’s subjacobian, to compute a set of two joint singularities. These singular curves define regions on the spherical surface that may or may not be accessible. A perturbation technique is then used to identify singular curve segments that are boundary to the workspace region. The methodology is illustrated through a numerical example.

The Debye theory of solid-state heat capacities

2021 ◽  
pp. 295-309
Author(s):  
Geoffrey Brooker
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Classical Limit ◽  
Degrees Of Freedom ◽  
Linear Chain ◽  
Heat Capacities ◽  
Debye Theory ◽  
State Heat ◽  
Equipartition Of Energy ◽  
Reasonable Step

“The Debye theory of solid-state heat capacities” gives a careful account of the Debye cut-off. We start by looking at a monatomic linear chain, leading to degrees of freedom and the equipartition of energy at the high-temperature (classical) limit. Reasonable approximations lead more naturally to the Born–von Karman model than to Debye, but Debye follows via a further reasonable step.

A Microcontroller Approach to Measuring Transmissibility of MEMS Devices

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001564-001593
Author(s):  
Chong Li ◽  
Yixuan Wu ◽  
Haoyue Yang ◽  
Luke L. Jenkins ◽  
Robert N. Dean ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Real Time ◽  
High Speed ◽  
Mechanical Quality Factor ◽  
Quantization Noise ◽  
Mems Devices ◽  
Input And Output ◽  
Mechanical Quality ◽  
Mems Device

The transmissibility reveals two very useful characteristics of a micro-electro-mechanical systems (MEMS) device, the resonant frequency and the mechanical quality factor. Real time knowledge on these two important factors can enhance application performance or avoid potential problems from environmental disturbances due to fabrication tolerances and the resulting operational differences in otherwise identical devices. Expensive laboratory equipment is typically used to measure the transmissibility. However, these test systems are not readily adaptable to field use. Therefore, it is important to be able to measure the transmissibility using a real time technique with a simplified test setup. This study proposes a technique that can compute the transmissibility in real time using a low cost microcontroller. This technique utilizes two laser vibrometers to detect the input and output motions of the proof mass in a MEMS device, which are fed to high speed 500 KHz analog to digital converters (ADC) in the microcontroller. A filtering step is performed to decrease noise. After the sampling and pre-filtering, a Fast Fourier Transform (FFT) is performed to convert the time-domain signals to frequency domain signals. The amplitude of the output signal at each frequency is divided by the amplitude of the corresponding input signal at each frequency to obtain the transmissibility. To overcome the difficulties resulting from measurement and quantization noise, a recursive calculating algorithm and a de-quantization filter are introduced. The recursive calculating process guarantees that the system updates the results continually, which results in a transmissibility plot covering the entire bandwidth. The de-quantization filter considers the validity of the data and performs the transmissibility division step accordingly. A cantilevered structure was chosen as the device-under-test to verify and evaluate this technique. The cantilevered device was attached to an electromechanical shaker system for vibratory stimulation. Two laser vibrometers were used to detect the input and output motion and this data was fed into a microcontroller. The microcontroller was STM32F407, which is 32-bit and 168 MHz controller. The tests demonstrated that this technique can measure the transmissibility and therefore the resonant frequency and mechanical quality factor accurately compared to a professional signal analyzer.

scholarly journals Design and Fabrication of a Wideband Cymbal Transducer for Underwater Sensor Networks

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4659 ◽  
Author(s):  
Hayeong Shim ◽  
Yongrae Roh
Keyword(s):  
Power Efficiency ◽  
Structural Parameters ◽  
Mechanical Quality Factor ◽  
Voltage Response ◽  
Underwater Sensor Networks ◽  
The Finite Element Method ◽  
Network Systems ◽  
Power Requirement ◽  
Cymbal Transducer ◽  
Mechanical Quality

Cymbal transducers are characterized by a high mechanical quality factor and low power efficiency. The research conducted so far on cymbal transducers has focused on improving the power efficiency and structural stability, but modern underwater sensor network systems need transducers to have a wide frequency bandwidth as well. In this study, a wideband cymbal transducer was designed to fill that need. First, the effect of various structural parameters on the performance of the cymbal transducer was analyzed with emphasis on the bandwidth using the finite element method. Based on the analysis results, the structure of the cymbal transducer was optimized to have the widest possible bandwidth while maintaining its transmitting voltage response (TVR) level over a typical power requirement as well. The validity of the design was verified by fabricating a prototype of the optimized cymbal transducer and comparing its measured performance with the design.

scholarly journals Electret formation in transition metal oxides by electrochemical amorphization

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yong-Jin Kim ◽  
Chan-Ho Yang
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Charge Density ◽  
Electric Fields ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Permanent Magnets ◽  
Underlying Mechanism ◽  
Diffusion Reaction ◽  
Wide Range

AbstractTransition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO3 thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm−2 and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.

scholarly journals Association between antenatal blood pressure and 5-year postpartum retinal arteriolar structural and functional changes

2019 ◽  
Vol 4 (1) ◽  
pp. e000355 ◽  
Author(s):  
Ralene Sim ◽  
Izzuddin Aris ◽  
Yap-Seng Chong ◽  
Tien Yin Wong ◽  
Ling-jun Li
Keyword(s):  
Blood Pressure ◽  
Mediation Analysis ◽  
Degrees Of Freedom ◽  
Underlying Mechanism ◽  
Structure And Function ◽  
Functional Changes ◽  
Microvascular Changes ◽  
And Function ◽  
Retinal Arteriolar

ObjectiveStudies have shown that hypertensive disorders of pregnancy (HDP) are associated with both postpartum retinal microvascular changes and cardiovascular (CV) risks. However, the underlying mechanism of HDP transitioning to microvascular and macrovascular changes remains unknown, due to the interaction between microvasculature and CV risks. In this study, we examined whether associations between antenatal systolic blood pressure (SBP) and postpartum retinal arteriolar changes are independent of postpartum CV risks.MethodsWe included 276 Singaporean mothers attending both baseline index pregnancy (2009–2010) and 5-year postpartum follow-up visits (2014–2015). We measured SBP at baseline. At follow-up, we assessed retinal microvascular structure and function with retinal photography and dynamic vessel analyser, together with CV risks using a validated 2008 Framingham Risk Score (FRS). We performed a traditional four-step mediation analysis using linear regression by adjusting for a series of baseline characteristics: age, ethnicity, college degree, prepregnancy body mass index and gestational diabetes mellitus diagnosis at baseline.ResultsWe found that each 10 mm Hg increase in baseline SBP was associated with reduced arteriolar calibre (−1.3 µm; 95% CI −3.0 to 0.2) and fractal dimension (−0.4 degrees of freedom (df); −1.0 to 0.2), and significantly with increased arteriolar constriction (0.5%; 0.001 to 1.0) at 5-year postpartum. Even though baseline SBP was associated with postpartum FRS, the latter was not associated with any retinal arteriolar measures. Therefore, no further mediation analysis was required.ConclusionOur study suggested that elevated SBP during pregnancy was associated with suboptimal retinal arteriolar structure and function independent of postpartum CV risks.

Sign in / Sign up

Export Citation Format

Share Document