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831.
Mechanical strengthening of a Si cantilever by applying KOH wet etching was investigated. Two kinds of Si cantilever specimens having the different crystallographic orientations of the sidewall surfaces, i.e., Si{100} and Si{110}, were fabricated from the same SOI wafer by a Bosch process. The typical height and pitch of the scalloping formed on the sidewall were 248 and 917 nm, respectively. A 50 % KOH (40 °C) chemical wet etching was applied to increase the fracture stress of the Si cantilever. The fracture stress in the both of Si{100} and Si{110} cantilevers increased with the advance of the etching. The obtained maximum fracture stress in Si{100} and Si{110} were 4.2 and 3.7 GPa, respectively. Sidewall surface of the cantilever was analyzed to investigate the mechanical strengthening of Si cantilever by wet etching. The etched surface crystalline was analyzed by the transmission electron microscope (TEM), and confirmed that the thickness of the affected flow layer was less than 10 nm from the obtained TEM image. Then the change of the surface roughness by the KOH etching was analyzed by the atomic force microscope. The surface was smoothened with the advance of the KOH etching. The roughness value of Ra in Si{100} and Si{110} decreased to 12.1 and 37.7 nm, respectively.  相似文献   
832.
A new type of resonant pressure sensor is presented which is realized by combination of a double-ended tuning fork (DETF) quartz resonator and a silicon diaphragm. To examine the feasibility and investigate the performance of this innovation, theoretical analysis and finite elements method are employed to optimize the structure parameters. Micromachining technology are involved in the fabrication of the silicon diaphragm and the DETF quartz resonator, which are fabricated separately and bounded together afterwards. Performances of the sensor prototypes are experimentally investigated. Preliminary testing results demonstrate that the sensor features a high sensitivity of approximately 452.5 Hz/kPa in the operating range of 0–6 kPa at room temperature, with a non-linearity <0.035 % FS and a hysteresis of 0.055 % FS. In addition, the maximum zero-drift is about 0.5 Hz/h which reveals favorable frequency stability. Thus, the feasibility of this scheme is verified. Due to the excellent performances such as high accuracy, high sensitivity, low cost and simple fabrication, this novel resonant sensor provides a commendable solution for low pressure measurement.  相似文献   
833.
In this paper a novel MEMS tunable CPW antenna with wide tuning range of frequency is presented. The antenna’s frequency tuning range increment is achieved by loading three novel large tuning range capacitors at radiation edge of antenna patch. Two techniques are employed for increasing the capacitors tuning range. First, dual gap technique is used to overcome the pull-in limitation and then two lateral beams are added in order to parallel movement of capacitive plate which increases the capacitance value. The simulation result shows that the resonance frequency tuning range of antenna increased from 1.96 GHz loaded by traditional capacitor to 6.89 GHz using the new capacitor structure. Also in resonance frequency, the antenna has a good impedance matching with transmission line even in high capacitance values.  相似文献   
834.
835.
836.
Image geo-tagging has drawn a great deal of attention in recent years. The geographic information associated with images can be used to promote potential applications such as location recognition or virtual navigation. In this paper, we propose a novel approach for accurate mobile image geo-tagging in urban areas. The approach is able to provide a comprehensive set of geo-context information based on the current image, including the real location of the camera and the viewing angle, as well as the location of the captured scene. Moreover, the parsed building facades and their geometric structures can also be estimated. First, for the image to be geo-tagged, we perform partial duplicate image retrieval to filter crowd-sourced images capturing the same scene. We then employ the structure-from-motion technique to reconstruct a sparse 3D point cloud of the scene. Meanwhile, the geometric structure of the query image is analyzed to extract building facades. Finally, by combining the reconstructed 3D scene model and the extracted structure information, we can register the camera location and viewing direction to a real-world map. The captured building location and facade orientation are also aligned. The effectiveness of the proposed system is demonstrated by experiment results.  相似文献   
837.
We have developed a meter-scale light emitting diode (LED)-embedded light fabric and its weaving machine for application to a light device for fabric ceilings, which have recently become desired for lightweight safe ceilings in Japan and other countries with frequent earthquakes. The LED fabric structure is 1.2-m-wide woven fabric that has 5-mm-wide LED chip-mounted printed circuit board (PCB) tapes as wefts. LEDs are mounted on the tape of PCBs with a reel-to-reel chip mounting system. Then, the LED-mounted tapes are woven with a developed automatic looming machine that aligns the weft with an accuracy of 0.9 mm, which is suitable for precise arrangement of LEDs and wiring to power supply. A 1.2 × 1.2 m LED-embedded light fabric weighing 320 g/m2 was woven. The luminance of the LED fabric is 353 lx at a distance of 1 m, which is the luminance of conventional office lighting. The temperature increase of LEDs without a rigid cooling aluminum plate is only 5.8 °C, and the LED fabric is flexible enough to sustain 1,000 bends down to a radius of 3 mm. This LED fabric and its weaving technology will lead to light devices that have lightweight, large area, and high flexibility for fabric ceilings, walls, and other large areas in homes and offices.  相似文献   
838.
This paper focuses on the computational and experimental study of dielectrophoretic (DEP) force based manipulation of spherical and non-spherical particles by taking into consideration of both electrokinetic effects and particle hydrodynamics. The model is first validated with conventional dipole moment theory. The movements of a spherical polystyrene particle and a rod-shape particle under a non-uniform electric field created by a pair of non-symmetrical electrodes in a microfluidic channel are studied, and a good agreement between the simulation and experimental results is obtained. Both experimental and simulation results reveal that the rod-shape particle experiences larger DEP force and moves faster than spherical particle with a similar mass. It was also interestingly found that the shape-dependent DEP force distribution on the microscale rod particle results in its unique behavior, which cannot be captured by traditional DEP theory.  相似文献   
839.
Finding logos in the real-world images is a challenging task due to their small size, simple shape, less texture and clutter background. In this paper, through visual logo analysis with different types of features, we propose a novel framework for finding visual logos in the real-world images. First, we exploit the contextual shape and patch information around feature points, merge them into a combined feature representation (point-context). Considering the characteristics of logos, this kind of fusion is an effective enhancement for the discriminability of single point features. Second, to eliminate the interference of the complex and noisy background, we transfer the logo recognition to a region-to-image search problem by segmenting real-world images into region trees. A weak geometric constraint based on regions is encoded into an inverted file structure to accelerate the search process. Third, we apply global features to refine initial results in the re-ranking stage. Finally, we combine each region score both in max-response and accumulate-response mode to obtain the final results. Performances of the proposed approach are evaluated on both our CASIA-LOGO dataset and the standard Flickr logos 27 dataset. Experiments and comparisons show that our approach is superior to the state-of-the-art approaches.  相似文献   
840.
Variational functionals such as Mumford-Shah and Chan-Vese methods have a major impact on various areas of image processing. After over 10 years of investigation, they are still in widespread use today. These formulations optimize contours by evolution through gradient descent, which is known for its overdependence on initialization and the tendency to produce undesirable local minima. In this paper, we propose an image segmentation model in a variational nonlocal means framework based on a weighted graph. The advantages of this model are twofold. First, the convexity global minimum (optimum) information is taken into account to achieve better segmentation results. Second, the proposed global convex energy functionals combine nonlocal regularization and local intensity fitting terms. The nonlocal total variational regularization term based on the graph is able to preserve the detailed structure of target objects. At the same time, the modified local binary fitting term introduced in the model as the local fitting term can efficiently deal with intensity inhomogeneity in images. Finally, we apply the Split Bregman method to minimize the proposed energy functional efficiently. The proposed model has been applied to segmentation of real medical and remote sensing images. Compared with other methods, the proposed model is superior in terms of both accuracy and efficient.  相似文献   
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