1,237 research outputs found

    Dichloro[(1R,2R)-N-(2-pyridylmethylene)-1,2-cyclohexanediamine]copper(II)

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    The crystal structure of [CuC12(CI2Hi7N3)], containing a five-coordinate Cu n atom with distorted trigonalbipyramidal coordination, is reported. The absolute configuration (1R,2R) has been verified.published_or_final_versio

    Schools as spaces for in/exclusion of young Mainland Chinese students and families in Hong Kong

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    Around 30,000 children living in Shenzhen, Mainland China cross the border to Hong Kong to attend school every day. This paper focuses on the school as a key meso-level organisation that mediates macro-level policies and micro-level everyday life experiences among these children and their families. We advocate a relational, spatial perspective, conceptualising schools as webs of intersecting physical, social and digital spaces, where differences between the “locals” and “others” are played out, negotiated and (re)produced, and in turn giving rise to specific (and understudied) geographies of in/exclusion. Drawing on our qualitative research, we offer a close reading of three exemplary school spaces: (i) the physical classroom and school grounds, (ii) the digital classroom, and (iii) at the school gate. Our findings demonstrate the complex and at times contradictory ways in which “the school” is a place of both inclusion and exclusion. It is a dynamic and power-traversed space where social differences between the “locals” and the “others” are played out, contested and redefined continuously

    Factors affecting ventilation effectiveness in SARS wards

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    Reference-free detection of semiconductor assembly defect

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    This paper aims at developing a novel defect detection algorithm for the semiconductor assembly process by image analysis of a single captured image, without reference to another image during inspection. The integrated circuit (IC) pattern is usually periodic and regular. Therefore, we can implement a classification scheme whereby the regular pattern in the die image is classified as the acceptable circuit pattern and the die defect can be modeled as irregularity on the image. The detection of irregularity in image is thus equivalent to the detection of die defect. We propose a method where the defect detection algorithm first segments the die image into different regions according to the circuit pattern by a set of morphological segmentations with different structuring element sizes. Then, a feature vector, which consists of many image attributes, is calculated for each segmented region. Lastly, the defective region is extracted by the feature vector classification. © 2005 SPIE and IS&T.published_or_final_versio

    Regularized multiframe phase-shifting algorithm for three-dimensional profilometry

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    In many industrial inspection systems, it is required to have a high-precision three-dimensional measurement of an object under test. A popular technique is phase-measuring profilometry. In this paper, we develop some phase-shifting algorithms (PSAs). We propose a novel smoothness constraint in a regularization framework; we call this the R-PSA method and show how to obtain the desired phase measure with an iterative procedure. Both the simulation and experimental results verify the efficacy of our algorithm compared with current multiframe PSAs for interferometric measurements.published_or_final_versio

    Three-dimensional reconstruction of wafer solder bumps using binary pattern projection

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    As the electronic industry advances rapidly, the shrunk dimension of the device leads to more stringent requirement on process control and quality assurance. For instance, the tiny size of the solder bumps grown on wafers for direct die-to-die bonding pose great challenge to the inspection of the bumps' 3D quality. Traditional pattern projection method of recovering 3D is about projecting a light pattern to the inspected surface and imaging the illuminated surface from one or more points of view. However, image saturation and the specular nature of the bump surface are issues. This paper proposes a new 3D reconstruction mechanism for inspecting the surface of such wafer bumps. It is still based upon the light pattern projection framework, but uses the Ronchi pattern - a pattern that contrasts with the traditionally used gray level one. With the use of a parallel or point light source in combination with a binary grating, it allows a discrete pattern to be projected onto the inspected surface. As the projected pattern is binary, the image information is binary as well. With such a bright-or-dark world for each image position, the above-mentioned difficult issues are avoided. Preliminary study shows that the mechanism holds promises that existing approaches do not. © 2005 SPIE and IS&T.published_or_final_versio

    Structured-light based sensing using a single fixed fringe grating: Fringe boundary detection and 3-D reconstruction

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    Advanced electronic manufacturing requires the 3-D inspection of very small surfaces like the solder bumps on wafers for direct die-to-die bonding. Yet the microscopic size and highly specular and textureless nature of the surfaces make the task difficult. It is also demanded that the size of the entire inspection system be small so as to minimize restraint on the operation of the various moving parts involved in the manufacturing process. In this paper, we describe a new 3-D reconstruction mechanism for the task. The mechanism is based upon the well-known concept of structured-light projection, but adapted to a new configuration that owns a particularly small system size and operates in a different manner. Unlike the traditional mechanisms which involve an array of light sources that occupy a rather extended physical space, the proposed mechanism consists of only a single light source plus a binary grating for projecting binary pattern. To allow the projection at each position of the inspected surface to vary and form distinct binary code, the binary grating is shifted in space. In every shift, a separate image of the illuminated surface is taken. With the use of pattern projection, and of discrete coding instead of analog coding in the projection, issues like texture-absence, image saturation, and image noise of the inspected surfaces are much lessened. Experimental results on a variety of objects are presented to illustrate the effectiveness of this mechanism. © 2008 IEEE.published_or_final_versio
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