VLSI architecture for a Reed-Solomon decoder

A basic single-chip building block for a Reed-Solomon (RS) decoder system is partitioned into a plurality of sections, the first of which consists of a plurality of syndrome subcells each of which contains identical standard-basis finite-field multipliers that are programmable between 10 and 8 bit operation. A desired number of basic building blocks may be assembled to provide a RS decoder of any syndrome subcell size that is programmable between 10 and 8 bit operation

Development of Motorized Azimuthal Scanners for Ultrasonic NDE Of Composites

Composites are a material class for which nondestructive material property characterization is as important as flaw detection. Fiber reinforced composite laminates often possess strong in-plane elastic anisotropy attributable to the specific fiber orientation and layup sequence. Many of these elastic anisotropies may be investigated using ultrasound [1–6], among which angular measurements are often used. Hsu et al [3,4] used angular scan of acousto-ultrasonic signals to investigate fiber reinforced composite laminates. By placing and rotating two contact transducers on the same side of crossedplied composite laminates, the angular dependence of the acousto-ultrasonic signal was measured and found to have good correlation with the fiber orientation of the sample. Angular measurement of normal-incident shear wave has also been used to detect errors in layup sequence and ply orientation in both green (before cured) and cured composites [4–6]. The transmitted signals of normal incident shear wave in a “crossed polarizer” configuration were found to be particularly sensitive to ply misorientation and layup sequence in a laminate. For green composites, sandwiched between aluminum delay lines, EMATs (electro-meganetic transducer) were used so that the problem of changing coupling condition during the angular scan was avoided. This technique was believed to hold good potential as a practical NDE tool for detecting layup errors during the manufacturing process [5]

VLSI single-chip (255,223) Reed-Solomon encoder with interleaver

The invention relates to a concatenated Reed-Solomon/convolutional encoding system consisting of a Reed-Solomon outer code and a convolutional inner code for downlink telemetry in space missions, and more particularly to a Reed-Solomon encoder with programmable interleaving of the information symbols and code correction symbols to combat error bursts in the Viterbi decoder

Method for Veterbi decoding of large constraint length convolutional codes

A new method of Viterbi decoding of convolutional codes lends itself to a pipline VLSI architecture using a single sequential processor to compute the path metrics in the Viterbi trellis. An array method is used to store the path information for NK intervals where N is a number, and K is constraint length. The selected path at the end of each NK interval is then selected from the last entry in the array. A trace-back method is used for returning to the beginning of the selected path back, i.e., to the first time unit of the interval NK to read out the stored branch metrics of the selected path which correspond to the message bits. The decoding decision made in this way is no longer maximum likelihood, but can be almost as good, provided that constraint length K in not too small. The advantage is that for a long message, it is not necessary to provide a large memory to store the trellis derived information until the end of the message to select the path that is to be decoded; the selection is made at the end of every NK time unit, thus decoding a long message in successive blocks

Architecture for time or transform domain decoding of reed-solomon codes

Two pipeline (255,233) RS decoders, one a time domain decoder and the other a transform domain decoder, use the same first part to develop an errata locator polynomial .tau.(x), and an errata evaluator polynominal A(x). Both the time domain decoder and transform domain decoder have a modified GCD that uses an input multiplexer and an output demultiplexer to reduce the number of GCD cells required. The time domain decoder uses a Chien search and polynomial evaluator on the GCD outputs .tau.(x) and A(x), for the final decoding steps, while the transform domain decoder uses a transform error pattern algorithm operating on .tau.(x) and the initial syndrome computation S(x), followed by an inverse transform algorithm in sequence for the final decoding steps prior to adding the received RS coded message to produce a decoded output message

Application of Shear Waves for Composite Laminate Characterization

The layup sequence in a composite laminate greatly effects its properties. If one ply is misaligned in the layup sequence, it can result in the part being rejected and discarded. At the present time, most manufacturers cut a small coupon from the waste edge and use a microscope to optically verify the ply orientations on critical parts. This can add a substantial cost to the product since the test is both labor intensive and performed after the part is cured. A nondestructive technique which could be used to test the part after curing and require less time than the optical test would be very beneficial, and one that could be performed prior to curing would be extremely desirable. Preliminary tests demonstrate a high probability that the model and tests developed in this paper can be used for characterizing uncured layups as well.</p

Direct observation of a liquid film under a vapor environment in a pool boiling using a nanofluid

The existence of a liquid film separating a vapor bubble from a heated solid surface is confirmed using a nanofluid. The existence of such a liquid film had been a theoretical premise of the critical heat flux mechanism, significantly difficult to verify through experimental observations. Here, we show that a liquid film under a massive vapor bubble adheres to a heated solid surface. The liquid film comes into being trapped in a dynamic coalescence environment of nucleate bubbles, which grow and depart continuously from the heated surface. In its dryout process, the liquid film displays vapor &quot;holes&quot; originating from the rupture of discrete nucleating bubbles. The dryout process of the liquid film can be understood from the vaporization of rims of the holes and of smooth film region.open51

Influence of terahertz waves on the fiber direction of CFRP composite laminates

The importance of Carbon-fiber reinforced plastics (CFRP) are widely utilized due to more high performance in engineering structures. It was well known that a nondestructive technique would be very beneficial. A new terahertz radiation has been recognized for their importance in technological applications. Recently, T-ray (terahertz ray) advances of technology and instrumentation has provided a probing field on the electromagnetic spectrum. The THz-TDS can be considered as a useful tool using general non-conducting materials; however it is quite limited to conducting materials. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configuration using the terahertz time domain spectroscopy. However, the T-ray is limited in order to penetrate a conducting material to some degree. Here, the T-ray would not go through easily the CFRP composite laminates since carbon fibers are electrically conducting while the epoxy matrix is not. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS (poly-phenylene sulfide)-based CFRP solid laminate. It is found that the electrical conductivity of CFRP composites depends on the direction of unidirectional fibers. Also, the T-ray could penetrate a CFRP composite laminate a few ply based on the E-filed (Electrical field) of carbon fibers. The terahertz scanning images were made at the angles ranged from 0° to 180° with respect to the nominal fiber axis. So, the images were mapped out based on the electrical field (E-field) direction in the CFRP solid laminates. Also, using two-dimensional spatial Fourier transform, interface C-scan images were transformed into quantitatively angular distribution plots to show the fiber orientation information therein and to predict the orientation of the ply

First-principles prediction of spin-density-reflection symmetry driven magnetic transition of CsCl-type FeSe

Based on results of density functional theory (DFT) calculations with the local spin density approximation (LSDA) and the generalized gradient approximation (GGA), we propose a new magnetic material, CsCl-type FeSe. The calculations reveal the existence of ferromagnetic (FM) and antiferromagnetic (AFM) states over a wide range of lattice constants. At 3.12\,{\AA} in the GGA, the equilibrium state is found to be AFM with a local Fe magnetic moment of $\pm 2.69\,\mu_\mathrm{B}$. A metastable FM state with Fe and Se local magnetic moments of $2.00\,\mu_\mathrm{B}$ and $-0.032\,\mu_\mathrm{B}$, respectively, lies 171.7\,{meV} above the AFM state. Its equilibrium lattice constant is $\sim 2$\,{\%} smaller than that of the AFM state, implying that when the system undergoes a phase transition from the AFM state to the FM one, the transition is accompanied by volume contraction. Such an AFM-FM transition is attributed to spin-density $z$-reflection symmetry; the symmetry driven AFM-FM transition is not altered by spin-orbit coupling. The relative stability of different magnetic phases is discussed in terms of the local density of states. We find that CsCl-type FeSe is mechanically stable, but the magnetic states are expected to be brittle.Comment: LaTeX,16 pages, 6 figure

Advanced microscopy to elucidate cardiovascular injury and regeneration: 4D light-sheet imaging

The advent of 4-dimensional (4D) light-sheet fluorescence microscopy (LSFM) has provided an entry point for rapid image acquisition to uncover real-time cardiovascular structure and function with high axial resolution and minimal photo-bleaching/-toxicity. We hereby review the fundamental principles of our LSFM system to investigate cardiovascular morphogenesis and regeneration after injury. LSFM enables us to reveal the micro-circulation of blood cells in the zebrafish embryo and assess cardiac ventricular remodeling in response to chemotherapy-induced injury using an automated segmentation approach. Next, we review two distinct mechanisms underlying zebrafish vascular regeneration following tail amputation. We elucidate the role of endothelial Notch signaling to restore vascular regeneration after exposure to the redox active ultrafine particles (UFP) in air pollutants. By manipulating the blood viscosity and subsequently, endothelial wall shear stress, we demonstrate the mechanism whereby hemodynamic shear forces impart both mechanical and metabolic effects to modulate vascular regeneration. Overall, the implementation of 4D LSFM allows for the elucidation of mechanisms governing cardiovascular injury and regeneration with high spatiotemporal resolution