scholarly journals Estimation of Air Damping in Out-of-Plane Comb-Drive Actuators

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 263 ◽  
Author(s):  
Ramin Mirzazadeh ◽  
Stefano Mariani
Keyword(s):  
Atmospheric Pressure ◽  
Finite Size ◽  
Computational Tools ◽  
Electrostatically Actuated ◽  
Air Damping ◽  
Comb Drives ◽  
Dissipation Mechanism ◽  
Fluid Damping ◽  
Out Of Plane ◽  
The Ideal

The development of new compliant resonant microsystems and the trend towards further miniaturization have recently raised the issue of the accuracy and reliability of computational tools for the estimation of fluid damping. Focusing on electrostatically actuated torsional micro-mirrors, a major dissipation contribution is linked to the constrained flow of air at comb fingers. In the case of large tilting angles of the mirror plate, within a period of oscillation the geometry of the air domain at comb-drives gets largely distorted, and the dissipation mechanism is thereby affected. In this communication, we provide an appraisal of simple analytical solutions to estimate the dissipation in the ideal case of air flow between infinite plates, at atmospheric pressure. The results of numerical simulations are also reported to assess the effect on damping of the finite size of actual geometries.

Finite-size effects in the ideal Fermi gas

1989 ◽  
Vol 22 (11) ◽  
pp. L489-L496 ◽  
Author(s):  
V Subrahmanyam ◽  
M Barma
Keyword(s):  
Size Effects ◽  
Finite Size ◽  
Fermi Gas ◽  
Finite Size Effects ◽  
The Ideal

LaCoste and Romberg straight‐line gravity meter

Geophysics ◽  
1983 ◽  
Vol 48 (5) ◽  
pp. 606-610 ◽  
Author(s):  
Lucien LaCoste
Keyword(s):  
Cross Coupling ◽  
Coupling Effects ◽  
New Model ◽  
Silicone Fluid ◽  
Air Damping ◽  
Straight Line ◽  
New Instrument ◽  
Spring Suspension ◽  
Fluid Damping ◽  
Rough Handling

The LaCoste and Romberg straight‐line gravity meter uses a new suspension in which the movable element moves vertically in a straight line rather than in an arc of a circle (LaCoste, 1973a). It was designed primarily for shipboard operation to avoid effects from cross coupling between various ship accelerations, thereby making it unnecessary to correct for such effects. The straight‐line suspension is a modification of the zero length spring suspension used in all LaCoste and Romberg gravity meters. The new model also uses silicone fluid damping rather than the air damping used in earlier models. Its main advantages over the older models appear to be: it is (1) free of cross‐coupling effects, (2) easier to build and adjust, (3) less subject to slight degradation in performance from rough handling, and (4) less sensitive to ship vibrations. In spite of the above advantages it is doubtful whether the new model will give substantially better accuracy than the previous models, if the previous models are kept in good operating condition by making occasional crosscorrelation analyses (LaCoste, 1973b). Valliant (1983, this issue) describes sea tests of the new instrument.

Design and Simulation of Capacitive Micromechaned Gyroscope

2011 ◽  
Vol 211-212 ◽  
pp. 909-913
Author(s):  
Yun Bo Shi ◽  
Xing Juan Zhao ◽  
Jun Tang ◽  
Jun Liu ◽  
Rui Rong Wang
Keyword(s):  
Atmospheric Pressure ◽  
Simulation Analysis ◽  
High Sensitivity ◽  
Drive Mode ◽  
Close Match ◽  
High Q ◽  
Air Damping ◽  
Large Numbers ◽  
Detection Mode ◽  
Micromachined Gyroscope

By researching and investigating the structure of capacitive gyroscopes, A novel capacitive micromachined gyroscope is proposed and the structure is designed. The method of electrostatic comber drive, capacitive detection of bar structure is used for the structure, and these make the gyroscope high sensitivity. The main air damping of the drive mode and detection mode is slide film damping, it is possible to make the gyroscope achieve high Q-values at atmospheric pressure. The decoupled gyroscope is designed, too. By large numbers of simulation analysis， frequencies of the first six steps mode are gained, nature frequencies of drive mode and sense mode of gyroscope are a close match, and rationality of the structure is validated. At last, the structure encapsulated is presented.

scholarly journals Epitaxial Growth of Magnesia Films on Single Crystalline Magnesia Substrates by Atmospheric-Pressure Chemical Vapor Deposition

2016 ◽  
Vol 5 (2) ◽  
pp. 56
Author(s):  
Keiji Komatsu ◽  
Pineda Marulanda David Alonso ◽  
Nozomi Kobayashi ◽  
Ikumi Toda ◽  
Shigeo Ohshio ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Single Crystal ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Reciprocal Lattice ◽  
Chemical Vapor ◽  
X Ray ◽  
Pole Figures ◽  
Out Of Plane ◽  
Pressure Chemical

<p class="1Body">MgO films were epitaxially grown on single crystal MgO substrates by atmospheric-pressure chemical vapor deposition (CVD). Reciprocal lattice mappings and X-ray reflection pole figures were used to evaluate the crystal quality of the synthesized films and their epitaxial relation to their respective substrates. The X-ray diffraction profiles indicated that the substrates were oriented out-of-plane during MgO crystal growth. Subsequent pole figure measurements showed how all the MgO films retained the substrate in-plane orientations by expressing the same pole arrangements. The reciprocal lattice mappings indicated that the whisker film showed a relatively strong streak while the continuous film showed a weak one. Hence, highly crystalline epitaxial MgO thin films were synthesized on single crystal MgO substrates by atmospheric-pressure CVD.</p>

scholarly journals Experimental Verification of Impact of Sprinkled Area Length on Heat Exchange Coefficient

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Petr Kracik ◽  
Marek Balas ◽  
Martin Lisy ◽  
Jiri Pospisil
Keyword(s):  
Gas Phase ◽  
Flow Rate ◽  
Atmospheric Pressure ◽  
Tube Bundle ◽  
New Technology ◽  
Thin Liquid Film ◽  
Flow Mode ◽  
Heat Exchange Coefficient ◽  
Flowing Fluid ◽  
The Ideal

On a sprinkled tube bundle, liquid forms a thin liquid film, and, in the case of boiling liquid, the liquid phase can be quickly and efficiently separated from the gas phase. There are several effects on the ideal flow mode and the heat transfer from the heating to the sprinkling liquid. The basic quantity is the flow rate of the sprinkling liquid, but also diameter of the tubes, pipe spacing of the tube bundle, and physical state of the sprinkling and heating fluid. Sprinkled heat exchangers are not a new technology and studies have been carried out all over the world. However, experiments (tests) have always been performed under strict laboratory conditions on one to three relatively short tubes and behaviour of the flowing fluid on a real tube bundle has not been taken into account, which is the primary aim of our research. In deriving and comparing the results among the studies, the mass flow rate based on the length of the sprinkled area is used, thus trying to adjust the different length of the heat exchanger. This paper presents results of atmospheric pressure experiments measured on two devices with different lengths of the sprinkled area but with the same number of tubes in the bundle with same pitch and surface at a temperature gradient of 15/40°C, where 15°C is the sprinkling water temperature at the outlet of the distribution pipe and 40°C is the temperature of heating water entering the bundle.

scholarly journals Wire Ropes and CFRP Strips to Provide Masonry Walls with Out-Of-Plane Strengthening

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2712
Author(s):  
Elena Ferretti
Keyword(s):  
Steel Wire ◽  
Three Dimensional ◽  
Maximum Load ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Wire Ropes ◽  
Out Of Plane ◽  
Beam Mechanism ◽  
Combined Technique ◽  
The Ideal

The present paper deals with an improvement of the strengthening technique consisting in the combined use of straps—made of stainless steel ribbons—and CFRP (Carbon Fiber Reinforced Polymer) strips, to increase the out-of-plane ultimate load of masonry walls. The straps of both the previous and the new combined technique pass from one face to the opposite face of the masonry wall through some holes made along the thickness, giving rise to a three-dimensional net of loop-shaped straps, closed on themselves. The new technique replaces the stainless steel ribbons with steel wire ropes, which form closed loops around the masonry units and the CFRP strips as in the previous technique. A turnbuckle for each steel wire rope allows the closure of the loops and provides the desired pre-tension to the straps. The mechanical coupling—given by the frictional forces—between the straps and the CFRP strips on the two faces of the masonry wall gives rise to an I-beam behavior that forces the CFRP strips to resist the load as if they were the two flanges of the same I-beam. Even the previous combined technique exploits the ideal I-beam mechanism, but the greater stiffness of the steel wire ropes compared to the stiffness of the steel ribbons makes the constraint between the facing CFRP strips stiffer. This gives the reinforced structural element a greater stiffness and delamination load. In particular, the experimental results show that the maximum load achievable with the second combined technique is much greater than the maximum load provided by the CFRP strips. Even the ultimate displacement turns out to be increased, allowing us to state that the second combined technique improves both strength and ductility. Since the CFRP strips of the combined technique run along the vertical direction of the wall, the ideal I-beam mechanism is particularly useful to counteract the hammering action provided by the floors on the perimeter walls, during an earthquake. Lastly, when the building suffers heavy structural damage due to a strong earthquake, the box-type behavior offered by the three-dimensional net of straps prevents the building from collapsing, acting as a device for safeguarding life.

The ideal pseudo-rigid continuum

2006 ◽  
Vol 462 (2074) ◽  
pp. 3185-3195 ◽  
Author(s):  
James Casey
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Royal Society ◽  
Recent Article ◽  
Finite Size ◽  
Rigid Bodies ◽  
Global Constraint ◽  
Restricted Class ◽  
The Ideal

In the literature on pseudo-rigid bodies and their applications, it is generally assumed that these bodies can undergo only a restricted class of motions, without questioning how this restriction is to be strictly enforced. In 2004, I proposed in these Proceedings that such a restriction may be regarded as a ‘global constraint’ on a deformable continuum, and influenced by ideas of Antman & Marlow from the early 1990s, I assumed that the constraint is enforced by a field of reactive stresses, and I constructed a mathematical model that idealizes pseudo-rigid bodies as globally constrained continua of finite size. In a recent article in Proceedings of the Royal Society A , the validity of this model was challenged. Essentially, the controversy revolves around the issue of working definitions versus idealized mathematical models of pseudo-rigid bodies.

Development of Latching Type Large Vertical-Travel Microactuator

2005 ◽  
Author(s):  
Risaku Toda ◽  
Eui-Hyeok Yang
Keyword(s):  
Plane Motion ◽  
Proof Of Concept ◽  
Test Device ◽  
Comb Drive ◽  
Pzt Actuator ◽  
Comb Drives ◽  
Out Of Plane ◽  
Sequential Activation ◽  
Vertical Travel

This paper describes design, fabrication and preliminary characterization of a proof-of-concept vertical-travel microactuator, providing linear motion and high precision positioning in space. The microactuator is capable of providing latching function when it is un-powered to maintain its position. The microactuator consists of two opposing comb drive actuator dies, a slider and bulk PZT actuators sandwiched between the dies. The slider is inserted between clutches. Comb drives are connected to the clutches to engage/disengage clutching. Sequential activation of the comb drives (in-plane motion) and the PZT actuator (out-of-plane motion) provides cumulative linear travel of the slider. The novelty of the slider insertion approach include (1) post-fabrication engagement of comb teeth enabling thick wafer DRIE process for comb drive actuators and (2) stressed tethers enabling zero-power latching. A test device was fabricated and assembled. By applying 100V∼300V DC to the electrostatic comb drive, lateral actuation of clutches was observed. Vertical actuation by PZT was also confirmed using WYKO RST plus interferometer.

scholarly journals Surface and Microstructure Analysis of CoCrPt Film on RuCoCrX (X = Ti, Re) Intermediate Layers

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 263
Author(s):  
Jai-Lin Tsai ◽  
Jyun-You Chen ◽  
Cheng Dai ◽  
Ting-Wei Hsu ◽  
Shi-Min Weng
Keyword(s):  
Intermediate Layer ◽  
Lattice Misfit ◽  
Anisotropy Constant ◽  
High Coercivity ◽  
Magnetic Anisotropy Constant ◽  
Residual Oxygen ◽  
Intermediate Layers ◽  
Out Of Plane ◽  
Large Asymmetry ◽  
The Ideal

The microstructural and magnetic properties of perpendicular anisotropic CoCrPt films deposited on Ru or RuCoCrX (X = Ti, Re) intermediate layers were studied. The c-axis of CoCrPt grains were promoted by (0002) textured RuCoCr, and RuCoCrX (X = Ti, Re) intermediate layers due to smaller lattice misfit as compared to Ru. The narrower rocking width (Δθ50 = 3.76°) in RuCoCrRe intermediate layer and CoCrPt shows higher out of plane coercivity (Hc = 6.2 kOe), magnetic anisotropy constant (Ku = 6.2 × 106 erg/cm3) and nucleation field (HN = −2.8kOe) as compared to the Ru intermediate layer (Hc = 5.4 kOe, Ku = 5.9 × 106 erg/cm3, HN = −1.6 kOe). The partial intergranular exchange decoupling of CoCrPt grains was observed. The grain boundaries oxides were formed by the residual oxygen in targets and sputtering processes. The minor Cr2O3, CoO, TiO2, ReO3 oxides were investigated by surface analysis. Due to the minor oxides and Cr segregation at grains boundaries, the CoCrPt films present high coercivity. Samples CoCrPt/RuCoCr and CoCrPt/RuCoCrTi present a minimum at 45° but the values are much higher than the ideal Stoner-Wohlfarth theoretical value 0.5 which could be due to fewer natural oxides for magnetic grains separation. In sample CoCrPt/RuCoCrRe, there is an increase of intergranular interaction as indicated by the large asymmetry and the shift of the minimum at lower angles.

Sign in / Sign up

Export Citation Format

Share Document