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排序方式: 共有133条查询结果,搜索用时 31 毫秒
1.
Chuang-Yuan Lee Eun Sok Kim 《Journal of microelectromechanical systems》2006,15(4):745-755
This paper describes the design, fabrication, and characterization of the first MEMS piezoelectric tunable capacitors employing zinc oxide (ZnO) actuation. Relatively simple design rules for the device-structure optimization for largest deflection are shown from simulation results based on theoretical equations. The ZnO-actuated tunable capacitors are accordingly designed and fabricated with both surface and bulk micromachining techniques. Through the surface micromachining process, sacrificial silicon is removed with XeF/sub 2/, and parylene is successfully used as a supporting layer for a piezoelectric unimorph cantilever. For comparison, other two different structures using plasma-enhanced chemical-vapor deposition (PECVD) SiN and SU-8 as supporting layers are also fabricated. Deflection analyses are performed for three specific structures, among which the parylene-supported one is demonstrated to have the largest displacement and most suitable for tunable capacitor application. For bulk-micromachined tunable capacitor, we have implemented a novel design of a large structure driven by a ZnO unimorph, and obtained a tuning ratio of more than 21:1 (0.46 pF-10.02 pF). This is the highest tuning ratio reported to date for parallel-plate tunable capacitors while requiring an applied voltage of only 35 V. 相似文献
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3.
This paper presents the design, fabrication, and characterization of a contactless radio frequency (RF) microelectromechanical system (MEMS) switch, composed of two surface-micromachined piezoelectric tunable capacitors and two bonded-wire inductors. The measured insertion loss and power isolation of the fabricated switch are 2.2 and 10.1 dB, respectively, with a capacitance variation of 4:1 over a narrow bandwidth near 2.2 GHz. This novel approach of using inductors eases the deflection requirement for the deformable bridge of the variable capacitor, and allows piezoelectric ZnO film to be used to deflect the capacitor bridge to vary the air gap, thus yielding a contactless RF switch. 相似文献
4.
With few exceptions, most of the existing noise reduction and data segmentation algorithms are only suited to image data. Therefore, an adaptive smoothing algorithm, with model-based masks, within a scale space framework is proposed for range data in this paper. This algorithm smoothes range data that conform to predefined, geometric models, while leaving other data points unaffected. The convergence of the algorithm in yielding dominant features is shown based on its compliance with the anisotropic diffusion concept. The weights of the smoothing masks are adaptively calculated according to the Mahalanobis distances between range data and model-based predictions. These behave as the diffusion coefficient in the anisotropic diffusion equation, thus satisfying the requirements of the causality criterion that no new features are introduced from fine to coarse scales. The computational complexity of this algorithm is examined and compared to that of the well-known RANSAC feature extraction algorithm. Unlike RANSAC, it has the advantage that the computational complexity is less affected by increasing the order of the model, and is independent of the number of model outliers. The proposed algorithm can be used to smooth range data in multiscale space by increasing the number of smoothing iterations. Robust, robot-occlusion-invariant features are then easily extracted from the smoothed data by least squares fitting algorithms. 相似文献
5.
Protective action of CLA against oxidative inactivation of paraoxonase 1, an antioxidant enzyme 总被引:2,自引:0,他引:2
The effect of CLA on paraoxonase 1 (PON1), one of the antioxidant proteins associated with HDL, was investigated for its protective
action against oxidative inactivation as well as its stabilization activity. When cis-9 (c9),trans-11 (t11)-CLA and t10,c12-CLA were examined for their protective activity against ascorbate/Cu2−-induced inactivation of PON1 in the presence of Ca2+, two CLA isomers exhibited a remarkable protection (E
max, 71–74%) in a concentration-dependent manner (50% effective concentration, 3–4 μM), characterized by a saturation pattern.
Such a protective action was also reproduced with oleic acid, but not linoleic acid. Rather, linoleic acid antagonized the
protective action of CLA isomers in a noncompetitive fashion. Additionally, the two CLA isomers also protected PON1 from oxidative
inactivation by H2O2 or cumene hydroperoxide. The concentration-dependent protective action of CLA against various oxidative inactivation systems
suggests that the protective action of CLA isomers may be mediated through their selective binding to a specific binding site
in a PON1 molecule. Separately, the inactivation of PON1 by p-hydroxymercuribenzoate (PHMB), a modifier of the cysteine residue, was also prevented by CLA isomers, suggesting the possible
existence of the cysteine residue in the binding site of CLA. The c9,t11-CLA isomer seems to be somewhat more effective than t10,c12-CLA in protecting against the inactivation of PON1 by either peroxides or PHMB, in contrast to the similar efficacy of
these two CLA isomers in preventing ascorbate/Cu2+-induced inactivation of PON1. Separately, CLA isomers successfully stabilized PON1, but not linoleic acid. These data suggest
that the two CLA isomers may play a beneficial role in protecting PON1 from oxidative inactivation as well as in its stabilization. 相似文献
6.
Pak Chanil An Kwangil Jang Paeksan Kim Jonggun Kim Sok 《Multimedia Tools and Applications》2019,78(9):12027-12042
Multimedia Tools and Applications - This paper introduces new simple and effective improved one-dimension(1D) Logistic map and Sine map made by the output sequences of two same existing 1D chaotic... 相似文献
7.
8.
Jae Wan Kwon Eun Sok Kim 《Journal of microelectromechanical systems》2005,14(3):603-609
This paper describes a wet-etching technique that solves the major difficulty of fine patterning a c-axis oriented polycrystalline ZnO film. The technique uses aqueous NH/sub 4/Cl with electrolytically added copper ions and convection flow, and for the first time, allows the ZnO film to be etched 1) with controlled etch rate ratio between the vertical and horizontal etch rates and 2) with controlled etch-front slope. The ratio between the vertical and horizontal etch rates is as high as 20 to 1, while the angle between the sidewall etch-front surface and the substrate surface can be electrically controlled between 73/spl deg/ and 106/spl deg/. Also, ZnO films can now be patterned to fine features (even sub-/spl mu/m level) with a wet etchant. The electroless galvanic etching technique described in this paper produces uniform etching over a large area (larger than 3" in diameter). 相似文献
9.
A label-free biosensor (for detection of DNA sequences) based on film-bulk-acoustic-resonator (FBAR) is presented in this letter. The FBAR's resonant frequency shifts to a lower value when a complementary single-strand DNA sequence is hybridized with a DNA probe sequence on an Au-coated FBAR surface. The sensor is capable of distinguishing a complementary DNA that is mismatched to a probe DNA by a single nucleotide. The label-free, highly sensitive and selective, and real-time detection of DNA sequence could easily be made into an array for combinatory DNA sequencing, and could possibly help geneticists to detect specific DNA sequences accurately and fast, without any expensive optical scanning or imaging. 相似文献
10.
Sok Won Kim K. Park S. H. Lee J. S. Kang K. H. Kang 《International Journal of Thermophysics》2007,28(3):1067-1073
Since the restrictions for environmental protection being strengthened, thermoplastics reinforced with natural fibers (NF’s),
such as jute, kenaf, flax, etc. have appeared as alternatives to chemical plastics for automobile interior materials. In this
study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composed of
50% polypropylene (PP) and 50% natural fiber (NF) irradiated by an electron beam (energy: 0.5 MeV, dose: 0–20 kGy) were measured.
The length and thickness of PP and NF are 80 ± 10 mm and 40–120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum, when
the dose of the electron beam was 10 kGy. However, the effect of the dose on the deformation was not clear. 相似文献