KEYWORDS: Convolution, Clocks, Very large scale integration, Information technology, Fourier transforms, Algorithm development, Statistical analysis, Data processing, Digital filtering, Computer architecture
This paper presents a hardware-efficient design for the one-dimensional (1-D) discrete Fourier transform (DFT). Once
the 1-D DFT is formulated as the cyclic convolution form, the first-order moments-based structure can be used as the
basic computing unit for the DFT computation, which only contains a control module, a statistical module and an
accumulation module. The whole calculation process only contains shift operations and additions, with no need for
multipliers and large memory. Compared with the traditional DA-based structure for DFT, the proposed design has better
performance in terms of the area-throughput ratio and the power consumption, especially when the length of DFT is
slightly longer. Similar efficient designs can be obtained for other computations, such as the DCT/IDCT, DST/IDST,
digital filter and correlation, by transforming them into the forms of the first-order moments-based cyclic convolution.
KEYWORDS: Image segmentation, Magnetic resonance imaging, Tissues, Tongue, Visualization, Fuzzy logic, 3D image processing, Data modeling, Head, Data acquisition
Continuing with our previous work of the segmentation and delineation of upper airway, the purpose of this work is to segment and delineate soft tissue organs surrounding the upper airway, such as adenoid, tonsils, fat pads and tongue, with the further goal of studying the relationship among the architectures of these structures, for understanding upper airway disorders in children. We use two MRI protocols, Axial T2 (used for adenoid, tonsil, and fat pads) and sagittal T1 (for tongue), to gather information about different aspects of the tissues. MR images are first corrected for background intensity variation and then the intensities are standardized. All segmentations are achieved via fuzzy connectedness algorithms with only limited operator interaction. A smooth 3D rendition of the upper airway and its surrounding tissues is displayed. The system has been tested utilizing 20 patient data sets. The tests indicate a 95% or better precision and accuracy for segmentation. The mean time taken per study is about 15 minutes including operator interaction time and processing time for all operations. This method provides a robust and fast means of assessing sizes, shapes, and the architecture of the tissues surrounding the upper airway, as well as providing data sets suitable for use in modeling studies of airflow and mechanics.
The purpose of this work is to build a computerized system for the delineation of upper airway structures via MRI and to evaluate its effectiveness for routine clinical use in aiding diagnosis of upper airway disorders in children. We use two MRI protocols, axial T1 and T2, to gather information about different aspects of the airway and its surrounding soft tissue structures including adenoid, tonsils, tongue and soft palate. These images are processed and segmented to compute the architectural parameters of the airway such as its surface description, volume, central (medial) line, and cross-sectional areas at planes orthogonal to the central line. We have built a software package based on 3DVIEWNIX and running on a 450 MHz Pentium PC under Linux system (and on a Sun workstation under Unix) for the various operations of visualization, segmentation, registration, prefiltering, interpolation, standardization, and quantitative analysis of the airway. The system has been tested utilizing 40 patient studies. For every study, the system segmented and displayed a smooth 3D rendition of the airway, its central line and a plot of the cross-sectional area of the airway orthogonal to the central line as a function of the distance from one end of the central line. The tests indicate 97% precision and accuracy for segmentation. The mean time taken per study is about 4 minutes for the airway. This includes operator interaction time and processing time. This method provides a robust and fast means of assessing the airway size, shape, and places of restriction, as well as providing a structural data set suitable for use in modeling studies of airflow and mechanics.
The aim of this paper is the precise and accurate quantification of brain tumor via MRI. This is very useful in evaluating disease progression, response to therapy, and the need for changes in treatment plans. We use multiple MRI protocols including FLAIR, T1, and T1 with Gd enhancement to gather information about different aspects of the tumor and its vicinity- edema, active regions, and scar left over due to surgical intervention. We have adapted the fuzzy connectedness framework to segment tumor and to measure its volume. The method requires only limited user interaction in routine clinical MRI. The first step in the process is to apply an intensity normalization method to the images so that the same body region has the same tissue meaning independent of the scanner and patient. Subsequently, a fuzzy connectedness algorithm is utilized to segment the different aspects of the tumor. The system has been tested, for its precision, accuracy, and efficiency, utilizing 40 patient studies. The percent coefficient of variation (% CV) in volume due to operator subjectivity in specifying seeds for fuzzy connectedness segmentation is less than 1%. The mean operator and computer time taken per study is 3 minutes. The package is designed to run under operator supervision. Delineation has been found to agree with the operators' visual inspection most of the time except in some cases when the tumor is close to the boundary of the brain. In the latter case, the scalp is included in the delineation and an operator has to exclude this manually. The methodology is rapid, robust, consistent, yielding highly reproducible measurements, and is likely to become part of the routine evaluation of brain tumor patients in our health system.
A new series of mixed borates of rare-earth elements and calcium with the composition R2CaB10O19 (where R represents rare-earth element) has been identified in the system R2O3-CaO-B2O3. These isostructural compounds exhibit a powder second harmonic generation (SHG) effect about twice larger than that of KDP (KH2PO4). The crystal structure of La2CaB10O19 (LCB), one member of the RCB family, has been determined by single crystal X-ray diffraction analysis. The compound crystallizes in the monoclinic system, space group C2, with a equals 11.043(3)angstrom, b equals 6.563(2)angstrom, c equals 9.129(2)angstrom, (alpha) equals (gamma) equals 90 degrees, (beta) equals 91.47 degrees, and two formula units per cell. LCB melts congruently with a melting point of 1065 plus or minus 2 degrees Celsius. Single crystals of LCB and Nd doped LCB in centimeter size have been grown from the stoichiometric melt. The preliminary results on properties of LCB are presented.
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