1,025 research outputs found
Nanonewton force generation and detection based on a sensitive torsion pendulum
In this paper, we introduce the experiment based on a sensitive torsion
pendulum for measuring and calibrating small forces at nanonewton scale. The
force standard for calibration is the universal gravitation between four masses
separated by known distances. It is realized by two test masses suspended as
the part of torsion pendulum and two source masses on a rotation table. Two
force generation mechanisms, optical force from radiation pressure and
electrostatic force by capacitive actuation unit, are designed and will be
calibrated by the gravitation force. We present our recent results of radiation
pressure measurements, and describe the design of capacitive displacement
sensing/actuating unit.Comment: This work has been presented on Conference on Precision
Electromagnetic Measurements, 8-13 June 2008, Broomfield, Colorad
User's manual for tooth contact analysis of face-milled spiral bevel gears with given machine-tool settings
Research was performed to develop a computer program that will: (1) simulate the meshing and bearing contact for face milled spiral beval gears with given machine tool settings; and (2) to obtain the output, some of the data is required for hydrodynamic analysis. It is assumed that the machine tool settings and the blank data will be taken from the Gleason summaries. The theoretical aspects of the program are based on 'Local Synthesis and Tooth Contact Analysis of Face Mill Milled Spiral Bevel Gears'. The difference between the computer programs developed herein and the other one is as follows: (1) the mean contact point of tooth surfaces for gears with given machine tool settings must be determined iteratively, while parameters (H and V) are changed (H represents displacement along the pinion axis, V represents the gear displacement that is perpendicular to the plane drawn through the axes of the pinion and the gear of their initial positions), this means that when V differs from zero, the axis of the pionion and the gear are crossed but not intersected; (2) in addition to the regular output data (transmission errors and bearing contact), the new computer program provides information about the contacting force for each contact point and the sliding and the so-called rolling velocity. The following topics are covered: (1) instructions for the users as to how to insert the input data; (2) explanations regarding the output data; (3) numerical example; and (4) listing of the program
Building a 3.5 m prototype interferometer for the Q & A vacuum birefringence experiment and high precision ellipsometry
We have built and tested a 3.5 m high-finesse Fabry-Perot prototype
inteferometer with a precision ellipsometer for the QED test and axion search
(Q & A) experiment. We use X-pendulum-double-pendulum suspension designs and
automatic control schemes developed by the gravitational-wave detection
community. Verdet constant and Cotton-Mouton constant of the air are measured
as a test. Double modulation with polarization modulation 100 Hz and
magnetic-field modulation 0.05 Hz gives 10^{-7} rad phase noise for a 44-minute
integration.Comment: This draft has been presented in the 5th Edoardo Amaldi Conference on
Gravitational Wave
Maxwell's two-demon engine under pure dephasing noise
The interplay between thermal machines and quantum correlations is of great
interest in both quantum thermodynamics and quantum information science.
Recently, a quantum Szil\'ard engine has been proposed, showing that the
quantum steerability between a Maxwell's demon and a work medium can be
beneficial to a work extraction task. Nevertheless, this type of quantum-fueled
machine is usually fragile in the presence of decoherence effects. We provide
an example of the pure dephasing process, showing that the engine's quantumness
can be degraded. Therefore, in this work, we tackle this question by
introducing a second demon who can access a control system and make the work
medium pass through two dephasing channels in a manner of quantum
superposition. Furthermore, we provide a quantum circuit to simulate our
proposed concept and test it on IBMQ and IonQ quantum computers.Comment: 10 pages, 7 figures, 2 table
Computerized Design and Generation of Low-Noise Gears with Localized Bearing Contact
The results of research projects directed at the reduction of noise caused by misalignment of the following gear drives: double-circular arc helical gears, modified involute helical gears, face-milled spiral bevel gears, and face-milled formate cut hypoid gears are presented. Misalignment in these types of gear drives causes periodic, almost linear discontinuous functions of transmission errors. The period of such functions is the cycle of meshing when one pair of teeth is changed for the next. Due to the discontinuity of such functions of transmission errors high vibration and noise are inevitable. A predesigned parabolic function of transmission errors that is able to absorb linear discontinuous functions of transmission errors and change the resulting function of transmission errors into a continuous one is proposed. The proposed idea was successfully tested using spiral bevel gears and the noise was reduced a substantial amount in comparison with the existing design. The idea of a predesigned parabolic function is applied for the reduction of noise of helical and hypoid gears. The effectiveness of the proposed approach has been investigated by developed TCA (tooth contact analysis) programs. The bearing contact for the mentioned gears is localized. Conditions that avoid edge contact for the gear drives have been determined. Manufacturing of helical gears with new topology by hobs and grinding worms has been investigated
Direct effects of caffeine on osteoblastic cells metabolism: the possible causal effect of caffeine on the formation of osteoporosis
BACKGROUND: Caffeine consumption has been reported to decrease bone mineral density (BMD), increase the risk of hip fracture, and negatively influence calcium retention. In this study, we investigated the influence of caffeine on the osteoblasts behaviour. METHOD: Osteoblasts derived from newborn Wistar-rat calvaria was used in this study. The effects of various concentrations of caffeine on bone cell activities were evaluated by using MTT assay. Alkaline phosphatase (ALP) staining, von Kossa staining and biochemical parameters including ALP, lactate dehydrogenase (LDH), prostaglandin E(2 )(PGE(2)) and total protein were performed at day 1, 3, and 7. DNA degradation analysis under the caffeine influence was also performed. RESULTS AND DISCUSSION: The results showed that the viability of the osteoblasts, the formation of ALP positive staining colonies and mineralization nodules formation in the osteoblasts cultures decreased significantly in the presence of 10 mM caffeine. The intracellular LDH, ALP and PGE(2 )content decreased significantly, the LDH and PGE(2 )secreted into the medium increased significantly. The activation of an irreversible commitment to cell death by caffeine was clearly demonstrated by DNA ladder staining. CONCLUSION: In summary, our results suggest that caffeine has potential deleterious effect on the osteoblasts viability, which may enhance the rate of osteoblasts apoptosis
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