The Experts below are selected from a list of 24699 Experts worldwide ranked by ideXlab platform
N Balasubramanian - One of the best experts on this subject based on the ideXlab platform.
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design and modeling of a nanomechanical sensor using silicon photonic crystals
Journal of Lightwave Technology, 2008Co-Authors: Chengkuo Lee, Jayaraj Thillaigovindan, Chii-chang Chen, R Radhakrishnan, N BalasubramanianAbstract:Conventionally a line Defect in the photonic crystal (PhC) is used to create a waveguide for light propagation through the PhC. A PhC based filter is designed by introducing micro-cavities within the line Defect so as to form the resonant bandgap structure for PhC. Such a PhC waveguide (PhCWG) filter shows sharp resonant peak in output waveLength spectrum. We proposed a suspended silicon bridge structure comprising this PhCWG filter structure. Since the output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. Shift of the output resonant waveLength is observed for suspended PhCWG beam structure under particular force loading. In other words, the induced strain modifies the shape of air holes and the spacing among them. Such an effect leads to shift of resonant waveLength. Under optical detection limitation of 0.1 nm for resonant waveLength shift, the sensing capability of this nanomechanical sensor is derived as that vertical deformation is 20-25 nm at the center and the smallest strain is 0.005% for Defect Length. This innovative design conceptualizes a new application area for PhCs, i.e., the nanometer-scale physical sensors for strains and forces.
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Optical NEMS Based Force Sensor Using Silicon Nanophotonics
2007 IEEE LEOS International Conference on Optical MEMS and Nanophotonics, 2007Co-Authors: Chengkuo Lee, Chii-chang Chen, R Radhakrishnan, N BalasubramanianAbstract:A line Defect in a silicon two-dimensional (2-D) photonic crystal (PhC) is created as a waveguide for light propagation via the PhC. By introducing micro-cavities within the line Defect so as to form the resonant band gap structure for PhC, we demonstrate a PhC waveguide (PhCWG) filter with clear resonant peak in output waveLength spectrum. We conceptualized a novel nanomechanical beam structure embedded with this PhCWG filter, i.e., a NEMS (Nanoelectromechanical system) based force sensor. Since the output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. Shift of the output resonant waveLength is correlated with beam deformation or force loading for this free-standing PhCWG beam. Simply speaking, the induced strain modifies the shape of air holes and the spacing among them for micro-cavities along the silicon waveguide of PhCWG For a silicon PhCWG beam structure with dimension of 340 nm(thickness) x 5 mum(width) x 20 mum(Length), the measurable vertical deformation of 20-25 nm at the center and detectable strain of Defect Length of 0.004% is derived according to simulation results.
Chengkuo Lee - One of the best experts on this subject based on the ideXlab platform.
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Computational study of an optical NEMS sensor
2009Co-Authors: Chengkuo Lee, Wenfeng Xiang, Fu-li HsiaoAbstract:Optical nanoelectromechanical systems (NEMS) based cantilever sensor embedded with a nanocavity resonator is investigated in this study. The resonant waveLength of output spectrum is sensitive to the shape of air holes and Defect Length of the nanocavity resonator. The sensor characteristics of NEMS-cantilevers with various Lengths and the same nanocavity structure are studied in air and water.
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optical nanomechanical sensor using a silicon photonic crystal cantilever embedded with a nanocavity resonator
Applied Optics, 2009Co-Authors: Chengkuo Lee, Jayaraj ThillaigovindanAbstract:We present in-depth discussion of the design and optimization of a nanomechanical sensor using a silicon cantilever comprising a two-dimensional photonic crystal (PC) nanocavity resonator arranged in a U-shaped silicon PC waveguide. For example, the minimum detectable strain, vertical deflection at the cantilever end, and force load are observed as 0.0133%, 0.37 mum, and 0.0625 muN, respectively, for a 30 mum long and 15 mum wide cantilever. In the graph of strain versus resonant waveLength shift, a rather linear relationship is observed for various data derived from different cantilevers. Both the resonant waveLength and the resonant waveLength shift of cantilevers under deformation or force loads are mainly a function of Defect Length change. Results point out that all these mechanical parameters are mainly dependent on the Defect Length of the PC nanocavity resonator. This new PC cantilever sensor shows promising linear characteristics as an optical nanomechanical sensor.
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design and modeling of a nanomechanical sensor using silicon photonic crystals
Journal of Lightwave Technology, 2008Co-Authors: Chengkuo Lee, Jayaraj Thillaigovindan, Chii-chang Chen, R Radhakrishnan, N BalasubramanianAbstract:Conventionally a line Defect in the photonic crystal (PhC) is used to create a waveguide for light propagation through the PhC. A PhC based filter is designed by introducing micro-cavities within the line Defect so as to form the resonant bandgap structure for PhC. Such a PhC waveguide (PhCWG) filter shows sharp resonant peak in output waveLength spectrum. We proposed a suspended silicon bridge structure comprising this PhCWG filter structure. Since the output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. Shift of the output resonant waveLength is observed for suspended PhCWG beam structure under particular force loading. In other words, the induced strain modifies the shape of air holes and the spacing among them. Such an effect leads to shift of resonant waveLength. Under optical detection limitation of 0.1 nm for resonant waveLength shift, the sensing capability of this nanomechanical sensor is derived as that vertical deformation is 20-25 nm at the center and the smallest strain is 0.005% for Defect Length. This innovative design conceptualizes a new application area for PhCs, i.e., the nanometer-scale physical sensors for strains and forces.
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Design and modeling of nanophotonic beam structures as optical NEMS sensors
Quantum Sensing and Nanophotonic Devices V, 2008Co-Authors: Chengkuo Lee, Jayaraj Thillaigovindan, Chii-chang Chen, R Radhakrishnan, Ya-ting Chao, John H. LauAbstract:Silicon photonic crystal (PhC) waveguide based resonator is designed by introducing a micro-cavity within the line Defect so as to form the resonant band gap structure for PhC. Free-standing silicon beam comprising this nanophotonic resonator structure is investigated. The output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. The resonant waveLength shift in the output spectrum is a function of force loading at the center of a suspended beam with PhC waveguide resonator. The sensing capability of this new nanomechanical sensor is derived as that vertical deformation is about 20nm at center and the smallest strain is 0.005% for Defect Length.
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Optical NEMS Based Force Sensor Using Silicon Nanophotonics
2007 IEEE LEOS International Conference on Optical MEMS and Nanophotonics, 2007Co-Authors: Chengkuo Lee, Chii-chang Chen, R Radhakrishnan, N BalasubramanianAbstract:A line Defect in a silicon two-dimensional (2-D) photonic crystal (PhC) is created as a waveguide for light propagation via the PhC. By introducing micro-cavities within the line Defect so as to form the resonant band gap structure for PhC, we demonstrate a PhC waveguide (PhCWG) filter with clear resonant peak in output waveLength spectrum. We conceptualized a novel nanomechanical beam structure embedded with this PhCWG filter, i.e., a NEMS (Nanoelectromechanical system) based force sensor. Since the output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. Shift of the output resonant waveLength is correlated with beam deformation or force loading for this free-standing PhCWG beam. Simply speaking, the induced strain modifies the shape of air holes and the spacing among them for micro-cavities along the silicon waveguide of PhCWG For a silicon PhCWG beam structure with dimension of 340 nm(thickness) x 5 mum(width) x 20 mum(Length), the measurable vertical deformation of 20-25 nm at the center and detectable strain of Defect Length of 0.004% is derived according to simulation results.
Jayaraj Thillaigovindan - One of the best experts on this subject based on the ideXlab platform.
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optical nanomechanical sensor using a silicon photonic crystal cantilever embedded with a nanocavity resonator
Applied Optics, 2009Co-Authors: Chengkuo Lee, Jayaraj ThillaigovindanAbstract:We present in-depth discussion of the design and optimization of a nanomechanical sensor using a silicon cantilever comprising a two-dimensional photonic crystal (PC) nanocavity resonator arranged in a U-shaped silicon PC waveguide. For example, the minimum detectable strain, vertical deflection at the cantilever end, and force load are observed as 0.0133%, 0.37 mum, and 0.0625 muN, respectively, for a 30 mum long and 15 mum wide cantilever. In the graph of strain versus resonant waveLength shift, a rather linear relationship is observed for various data derived from different cantilevers. Both the resonant waveLength and the resonant waveLength shift of cantilevers under deformation or force loads are mainly a function of Defect Length change. Results point out that all these mechanical parameters are mainly dependent on the Defect Length of the PC nanocavity resonator. This new PC cantilever sensor shows promising linear characteristics as an optical nanomechanical sensor.
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design and modeling of a nanomechanical sensor using silicon photonic crystals
Journal of Lightwave Technology, 2008Co-Authors: Chengkuo Lee, Jayaraj Thillaigovindan, Chii-chang Chen, R Radhakrishnan, N BalasubramanianAbstract:Conventionally a line Defect in the photonic crystal (PhC) is used to create a waveguide for light propagation through the PhC. A PhC based filter is designed by introducing micro-cavities within the line Defect so as to form the resonant bandgap structure for PhC. Such a PhC waveguide (PhCWG) filter shows sharp resonant peak in output waveLength spectrum. We proposed a suspended silicon bridge structure comprising this PhCWG filter structure. Since the output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. Shift of the output resonant waveLength is observed for suspended PhCWG beam structure under particular force loading. In other words, the induced strain modifies the shape of air holes and the spacing among them. Such an effect leads to shift of resonant waveLength. Under optical detection limitation of 0.1 nm for resonant waveLength shift, the sensing capability of this nanomechanical sensor is derived as that vertical deformation is 20-25 nm at the center and the smallest strain is 0.005% for Defect Length. This innovative design conceptualizes a new application area for PhCs, i.e., the nanometer-scale physical sensors for strains and forces.
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Design and modeling of nanophotonic beam structures as optical NEMS sensors
Quantum Sensing and Nanophotonic Devices V, 2008Co-Authors: Chengkuo Lee, Jayaraj Thillaigovindan, Chii-chang Chen, R Radhakrishnan, Ya-ting Chao, John H. LauAbstract:Silicon photonic crystal (PhC) waveguide based resonator is designed by introducing a micro-cavity within the line Defect so as to form the resonant band gap structure for PhC. Free-standing silicon beam comprising this nanophotonic resonator structure is investigated. The output resonant waveLength is sensitive to the shape of air holes and Defect Length of the micro-cavity. The resonant waveLength shift in the output spectrum is a function of force loading at the center of a suspended beam with PhC waveguide resonator. The sensing capability of this new nanomechanical sensor is derived as that vertical deformation is about 20nm at center and the smallest strain is 0.005% for Defect Length.
Yoshikazu Nakai - One of the best experts on this subject based on the ideXlab platform.
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Effect of Defect shape on rolling contact fatigue crack initiation and propagation in high strength steel
International Journal of Fatigue, 2016Co-Authors: Taizo Makino, Yutaka Neishi, Daiki Shiozawa, Shoichi Kikuchi, S. Okada, Kentaro Kajiwara, Yoshikazu NakaiAbstract:Abstract The objective of the present paper is to clarify the effect of shapes of circular hole Defects, orientated perpendicular to the surface, on rolling contact fatigue (RCF) crack initiation and propagation in high strength steel. RCF test and synchrotron radiation micro computed tomography (SR micro CT) imaging were conducted. In the case of a 15-μm-diameter Defect, the number of cycles of rolling contact to flaking occurring (flaking life) decreased with increasing Defect Length. In a comparison of the CT image and the SEM view, the shapes of Defects and the locations of the horizontal cracks were almost the same respectively. The mechanism of RCF crack propagation was discussed by finite element (FE) analysis. Defects led to higher tensile residual stress than that without Defects in the region where the Defect exists. The shear stress range at 0.1 mm in depth on the middle line of the Defect and the range of mode II stress intensity factor at the bottom of a vertical crack increased with increasing Defect Length. In the case of a Defect 50 μm in diameter, Defect Length does not affect flaking life. The reason for this is probably that the horizontal cracks form and propagate before vertical cracks grow to an effective size.
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Effect of Defect Length on rolling contact fatigue crack propagation in high strength steel
Fracture and Structural Integrity, 2015Co-Authors: Taizo Makino, Yutaka Neishi, Daiki Shiozawa, Shoichi Kikuchi, S. Okada, Kentaro Kajiwara, Yoshikazu NakaiAbstract:The objective of the present paper is to clarify the effect of Defect Length in depth direction on rolling contact fatigue (RCF) crack propagation in high strength steel. RCF test and synchrotron radiation micro computed tomography (SR micro CT) imaging were conducted. In the case of the Defect with the 15 ?m diameter, flaking life decreased with increasing Defect Length. In a comparison of the CT image and the SEM view, the shapes of Defects and the locations of the horizontal cracks were almost the same respectively. The mechanism of RCF crack propagation was discussed by finite element (FE) analysis. Defects led to higher tensile residual stress than that without Defects in the region where the Defect exists. The shear stress range at 0.1 mm in depth on the middle line of the Defect and the range of mode II stress intensity factor at the bottom of a vertical crack increased with increasing Defect Length.
A R Mundy - One of the best experts on this subject based on the ideXlab platform.
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the type of urethroplasty for a pelvic fracture urethral distraction Defect cannot be predicted preoperatively
The Journal of Urology, 2003Co-Authors: Daniela E Andrich, Tamsin Greenwell, Kiaran Omalley, D J Summerton, A R MundyAbstract:ABSTRACTPurpose: Pelvic fracture urethral distraction Defects (PFUDDs) are generally treated surgically by a so-called progression approach consisting of 4 steps to achieve a tension-free bulboprostatic anastomosis. Implicitly the need for each step in turn is predictable according to the Length of the Defect on preoperative x-ray.Materials and Methods: In 62 evaluable patients with PFUDD the Length of the radiological Defect was compared with the surgical steps that subsequently proved necessary to achieve a tension-free bulboprostatic anastomosis.Results: Except at the extremes of Length there was no association between Defect Length and the scale of the surgery performed.Conclusions: Surgeons preparing to repair an apparently short PFUDD cannot assume that simple repair is all that is necessary.
