Papers by Keyword: Alignment

Abstract: Rapid growth in modern technology places greater requirements on electronic products' performance and quality. For a PCB (printed circuit board) assembly of SMT (surface mounting technology) electronic components, restricted by its limited vision in image collection, a high-pixel CCD (charge coupled device) can only screen local images, and they need to be mosaiced, through matching and alignment, into a complete image, which is to be matched and aligned with a standard image then for image analysis. Therefore, image matching and alignment are of crucial importance to both the precision of image mosaic and the quality of SMT components. This paper proposed a sub-pixel based method, by which local images are marked, matched and aligned into a mosaiced image, which is matched and aligned with a standard image. The error analyses of matching and alignment for four common markers, i.e. circle, ellipse, square and rectangle, show that a square or rectangle marker is preferred for SMT electronic components; when the marker's center point serves as alignment point and the marked data are processed by sub-pixel algorithm, the alignment error can be reduced to about 0.2 pixel point, besides the sub-pixel based method can greatly improve precision when noise is fixed.

Abstract: Electrospinning offers a versatile way to produce micrometer or nanometer fibers; however, electrospun fibers are typically collected in a random orientation limiting their applications. In the present study, we used the high speed rotational roller fixed with parallel sticks and an auxiliary electrode at the splitting zone of jet flows to control the fiber orientation. Because of the electrostatic forces acting on the charged fibers spanning the gap between two sticks and tangential force of the rolling collector stretching fibers, together with the electrostatic force imposed by the auxiliary electrodes, the higher aligned fibers could be produced. The simultaneous application of a rotating drum and an auxiliary electrode in the spinning zone may provide a viable method of controlling the alignment of electrospun fibers.

Abstract: Solve the problem of simplifying, aligning, and restoring while rebuilding a large number of point group data. First, scanning art work by using 3DFAMILY laser scanner and obtain the 3D data of its surface, then removing the desultory points on the boundary, using curvature simplification and point position alignment to revise data. Finally, fixing the loophole and modify the convex block partially and finishing up 3D reconstruction. We transform the reconstruction result into STL format file, and build the prototype of art work in Rapid Prototyping System.

Abstract: In this Paper, we Propose an Alignment Method for Lift-Off on Shallow Grooves in Transparent Substrates without an Extra Mask. An Assistant Metal Layer Was Deposited on the Glass Substrate with Grooves to Increase the Reflectance, and then a Layer of Photoresist for Lift-Off Process Was Coated and Patterned Aligning with the Shallow Grooves. We Compared the Effect of Aluminum and Chromium Films with Different Thickness as Reflecting Layers. an Aluminum or Chromium Film with the Thickness Larger than 10nm Provides High Enough Image Contrast of Profile of the Alignment Marks Beneath the Photoresist. the Image Contrast of Contour Profile of the Marks Was Enhanced as the Thickness Increased. Lift-Off Process Was then Implemented on the Assistant Reflecting Layer. With a 20nm Cr Layer, we Successfully Did Lithography and Finished the Lift-Off Process to Pattern a Cr/Au Layer on Shallow Grooves in a Glass Wafer. Finally, the Assistant Cr Layer Was Removed Using Dry Etching. the Assistant Metal Layer Has No Undesirable Influence on the Following Process and the Device Property.

Abstract: Tripoding the camera is a standard solution to acquire aligned images useful for High Dynamic Range photography. On the other hand, the chance to use a hand-held digital camera is surely more practical and attractive for photographers. In this paper we propose a registration algorithm that recovers the alignment of several bracketed images using a progressive combination of homographies estimated from a set of image correspondences.

Abstract: Fluorene-thiophene copolymers having chiral and azobenzene substituents, PAzB4-T, were synthesized by the Pd-catalyzed Suzuki coupling method. We studied the aligning organization of the main chain of PAzB4-T with the activation of the attached functional groups by thermal annealing and photo-annealing processes. Circular dichroism (CD) measurements revealed that the thermally annealed PAzB4-T spin-coated films exhibited bisignate Cotton effects over the absorption regions of the polymer main chains and the azobenzene side chains due to the formation of chiral assemblies. After the photo-annealing process, which means linearly polarized light irradiation accompanied by thermal annealing, the PAzB4-T spin-coated films showed linear dichroism over the absorption region of the main chains, due to the alignment of azobenzene side chains against the electric field of the linearly polarized light. These results suggested that rigid conjugated polymers were successfully aligned by the alignment of functional groups with the external stimuli.

Abstract: We report new experimental and theoretical study of mechanical property of aligned and nonaligned (entangled) single walled carbon nanotubes (SWCNTs), and their effect on nanostructures. Experimentally, the contact mode atomic force microscopy cantilever tip is used to measure the Young’s modulus of aligned and nonaligned SWCNTs. The measured Young's modulus of aligned SWCNT bundles ranged between 1100 GPa (1.1 TPa) and 1300 GPa (1.3 TPa) with a relative uncertainty of 5 % whereas that of the entangled SWCNT bundles ranged between 500 GPa and 700 GPa. Young’s modulus increase with aligned SWCNT bundles and then increase their performance in nanostructure comparing with entangled SWCNT bundles. We put emphasis on the combination of physical modeling and reliability based design optimization of nanomaterials. After investigation, we could make suggestions such as how to improve the reliability of nanodevices and nanosystems, and how to reduce cost and economic rates.

Abstract: Diseases occurring to blood vessel are preferentially solved by replacing the vessel by an autologous graft. When it is not available, a synthetic graft is used which has low patency rates for small diameter (<6 mm) vessels. Tissue engineering of blood vessel aims to improve the performance of vascular substitutes. Bioreactors are used in vascular tissue engineering to mimic the mechanical and biochemical environment of blood vessel. A 2D bioreactor was custom made in order to impose a dynamical strain to silicone membrane receiving the collagen cell-based construct. Collagen gels with vascular smooth muscle cells cultured inside were subdued to maturation under dynamical uniaxial stretch regimes at 1Hz for 48 hours. The percentage of deformation encountered by the silicone membrane was measured by ImageJ. Collagen fibrils and porcine smooth muscle cells (PSMC) orientations were assessed by scanning electron microscopy (SEM). Results show that the study of mechanical conditioning on cell activity is an important issue for enhancing the alignment of collagen fibrils.

Abstract: The random errors exist in measuring with touch trigger probe. These errors are directly introduced into workpiece coordinate system with conventional alignment method. An enhanced measuring method is proposed in this paper to improve the accuracy of alignment for five-axis CNC machine tools. By using the method of least square, an error reference frame is constructed, and the relationship between the alignment parameters and the error reference frame is derived. An example of aircraft structural parts is presented to validate the presented method.

Abstract: Based on the communicating vessel principle, we present a new instrument for the measurement of bearing elevation change. A number of cups are attached to the bearings. They are linked with pipes and joints together to constitute a measurement network. Special features of the instrument to make the measurement easily and reliable, such as cup design, are presented. The instrument is used to monitor and analyze the elevation change of a 1000MW turbo-generator during the vacuum setup process. We find that the influence of vacuum on the elevation of bearing located on the exhaust cylinder is large. The maximum value is 1.8mm when vacuum changes from 0KPa to 90KPa. It causes unload of bearing #5~#8 and overload of bearing #2~#4. Adjustment project is given in the last of the paper to solve rub and pad fragment fault occurred in the unit. It is verified that the elevation adjustment for such kind of fault is valuable.