Packing scheme for mean-filtering of an 8 bit image

Filtering is one of the most well known low-level image processing procedures. In most filtering procedures, the potential capability of an ALU in a processor is not fully used. The authors propose a packed mean filtering scheme. The scheme packs several pixels into a unit and processes them simultaneously. Experiments are held under three distinct machines to evaluate the performance of the scheme. The result shows that the scheme enhances processing speed in all three environments     

An Algorithm for Volume Estimation Based on Polyhedral Approxi mation

A volume algorithm is established which uses the data generated by computed tomography (CT) or ultrasound scans. The algorithm is based on a polyhedral reconstruction of an object of interest. Phantom studies indicate that the algorithm calculated volume is accurate within 3 percent. In a controlled clinical experiment on a laboratory animal, the algorithm calculated volume showed a maximum error of about 5 percent. In less controllable applications to human clinical data, volume calculations showed variations ranging up to 16 percent.     

A Three-Dimensional Display System for Diagnostic Imaging Applications

Digitally formatted 3-D imaging will become increasingly important in medical diagnosis. What is the best trade-off of speed, picture quality, and storage requirements?     

<Emphasis Type="Italic">Ab Initio</Emphasis> Studies of Hydrogen Defects in CdTe

Using first-principles calculations based on density functional theory, we have investigated the nature of H defects in CdTe. The formation energy calculations indicate that the ground state position of the H inside the CdTe lattice depends on charge state: the lowest energy position for H⁰ and H⁺ is at the bond center site, while H⁻ prefers the tetrahedral interstitial site with Cd nearest neighbors (T_Cd). We find that H in CdTe acts as an amphoteric impurity. In p-type samples, H is in a positive charge state, acting as a donor to neutralize the free holes in the valence band, and in n-type samples H acquires an electron, compensating the donors in the sample.     

Design of Parasitic Inductance Reduction in GaN Cascode FET for High‐Efficiency Operation

This paper presents a method of parasitic inductance reduction for high‐speed switching and high‐efficiency operation of a cascode structure with a low‐voltage enhancement‐mode silicon (Si) metal–oxide–semiconductor field‐effect transistor (MOSFET) and a high‐voltage depletion‐mode gallium nitride (GaN) field‐effect transistor (FET). The method is proposed to add a bonding wire interconnected between the source electrode of the Si MOSFET and the gate electrode of the GaN FET in a conventional cascode structure package to reduce the most critical inductance, which provides the major switching loss for a high switching speed and high efficiency. From the measured results of the proposed and conventional GaN cascode FETs, the rising and falling times of the proposed GaN cascode FET were up to 3.4% and 8.0% faster than those of the conventional GaN cascode FET, respectively, under measurement conditions of 30 V and 5 A. During the rising and falling times, the energy losses of the proposed GaN cascode FET were up to 0.3% and 6.7% lower than those of the conventional GaN cascode FET, respectively.     

Restoration and spectral recovery of mid-infrared chemical images

Fourier transform infrared (FTIR) microspectroscopy is a powerful technique for label-free chemical imaging that has supplied important chemical information about heterogeneous samples for many problems across a variety of disciplines. State-of-the-art synchrotron based infrared (IR) microspectrometers can yield high-resolution images, but are truly diffraction limited for only a small spectral range. Furthermore, a fundamental trade-off exists between the number of pixels, acquisition time and the signal-to-noise ratio, limiting the applicability of the technique. The recently commissioned infrared synchrotron beamline, infrared environmental imaging (IRENI), overcomes this trade off and delivers 4096-pixel diffraction limited IR images with high signal-to-noise ratio in under a minute. The spatial oversampling for all mid-IR wavelengths makes the IRENI data ideal for spatial image restoration techniques. Here, we measured and fitted wavelength-dependent point-spread-functions (PSFs) at IRENI for a 74× objective between the sample plane and detector. Noise-free wavelength-dependent theoretical PSFs are deconvoluted from images generated from narrow bandwidths (4 cm(-1)) over the entire mid-infrared range (4000-900 cm(-1)). The stack of restored images is used to reconstruct the spectra. Restored images of metallic test samples with features that are 2.5 μm and smaller are clearly improved in comparison to the raw data images for frequencies above 2000 cm(-1). Importantly, these spatial image restoration methods also work for samples with vibrational bands in the recorded mid-IR fingerprint region (900-1800 cm(-1)). Improved signal-to-noise spectra are reconstructed from the restored images as demonstrated for a mixture of spherical polystyrene beads in a polyurethane matrix. Finally, a freshly thawed retina tissue section is used to demonstrate the success of deconvolution achievable with a heterogeneous, irregularly shaped, biologically relevant sample with distinguishing spectroscopic features across the entire mid-IR spectral range.     

A Process for Cf/SiC Composites Using Liquid Polymer Infiltration

A continuous carbon fiber/silicon carbide matrix composite material has been produced by a low-cost process. In this process the space in a two-dimensional carbon fiber preform is filled with a SiC powder by a pressure infiltration method. High particle packing densities are achieved within the fiber preform in this way. The compact body is heat-treated at 400°C to form a porous framework, which is then infiltrated with a liquid preceramic polymer, Ceraset^TM SN. Subsequently the infiltrated polymer is pyrolyzed in argon at 1300°C. The microstructure of the final composite is characterized, and mechanical properties of these composites are discussed.