Systolic arrays for Viterbi processing in communication systemswith a time-dispersive channel

The theory and design of systolic arrays for Viterbi processing in communication systems with a time-dispersive time-varying channel is discussed. The architecture, algorithms, and processor elements, for a two-dimensional systolic array are described. The array supports the branch metric computations required for an adaptive Viterbi processor. The array is designed so that computations propagate along the rows of the array, while data symbols propagate along the columns. All interprocessor data flow and connections within the array are nearest-neighbor. The array illustrates how the Viterbi-processor algorithms can be structured to achieve a high degree of computational concurrency. Variations in the array design are described and evaluated in terms of computational resource requirements and utilization and computational throughput. A high-bandwidth memory interface is proposed, and system design considerations are discussed     

Control of dynamic systems using fuzzy logic and neural networks

The use of artificial neural network is proposed for high-speed processing of rules in fuzzy logic controller (FLC). the logic element of an FLC is replaced by a single hidden layer feedforward network. the input and output fuzzy subsets are expressed it of numerical patterns. the network is trained using the back-propagation algori to establish fuzzy associations between the input and output fuzzy subsets. the inference mechanism of the network is compared with that of compositional law of inference. In the proposed implementation of FLC, all the rules are processed in paralle. This implementation has potential for high-speed processing of rules if the network is realized in hardware. the use of neural networks in fuzzy logic self-organizing is also ivestigated. © 1993 John Wiley & Sons, Inc.     

An alternative Kalman innovation filter approach for receiver position estimation based on GPS measurements

This article presents an alternative Kalman innovation filter approach for receiver position estimation, based on pseudorange measurements of the global positioning system. First, a dynamic pseudorange model is represented as an ARMAX model and a pseudorange state-space innovation model suitable for both parameter identification and state estimation. The Kalman gain in the pseudorange coordinates is directly calculated from the identified parameters without prior knowledge of the noise properties and the receiver parameters. Then, the pseudorange state-space innovation model is transformed into the receiver state-space innovation model for optimal estimation of the receiver position. Hence, the proposed approach overcomes the drawbacks of the classical Kalman filter approach since it does not require prior knowledge of the noise properties, and the receiver's dynamic model to calculate the Kalman gain. In addition, due to its simplicity, it can be easily implemented in any receiver. To demonstrate the effectiveness of the approach, it is utilized to estimate the position of a stationary receiver and its performance is compared against two versions of the classical Kalman filter approach. The results show that the proposed approach yields consistently good estimation of the receiver position and outperforms the other methods.     

Characterization of the avian pathogenic Escherichia coli hemagglutinin Tsh, a member of the immunoglobulin A protease-type family of autotransporters

We reported earlier that a single gene, tsh, isolated from a strain of avian pathogenic Escherichia coli (APEC) was sufficient to confer on E. coli K-12 a hemagglutinin-positive phenotype and that the deduced sequence of the Tsh protein shared homology to the serine-type immunoglobulin A (IgA) proteases of Neisseria gonorrhoeae and Haemophilus influenzae. In this report we show that E. coli K-12 containing the recombinant tsh gene produced two proteins, a 106-kDa extracellular protein and a 33-kDa outer membrane protein, and was also able to agglutinate chicken erythrocytes. N-terminal sequence data indicated that the 106-kDa protein, designated Tshs, was derived from the N-terminal end of Tsh after the removal of a 52-amino-acid N-terminal signal peptide, while the 33-kDa protein, designated Tshbeta, was derived from the C-terminal end of Tsh starting at residue N1101. The Tshs domain contains the 7-amino-acid serine protease motif that includes the active-site serine (S259), found also in the secreted domains of the IgA proteases. However, site-directed mutagenesis of S259 did not abolish the hemagglutinin activity or the extracellular secretion of Tshs indicating that host-directed proteolysis was mediating the release of Tshs. Studies with an E. coli K-12 ompT mutant strain showed that the surface protease OmpT was not needed for the secretion of Tshs. Tsh belongs to a subclass of the IgA protease family, which also includes EspC of enteropathogenic E. coli, EspP of enterohemorragic E. coli, and SepA and VirG of Shigella flexneri, which seem to involve a host endopeptidase to achieve extracellular release of their N-terminal domains. In proteolytic studies conducted in vitro, Tshs did not cleave the substrate of the IgA proteases, human IgA1 or chicken IgA, and did not show proteolytic activity in a casein-based assay. Correlation of Tsh expression and hemagglutination activity appears to be a very complex phenomenon, influenced by strain and environmental conditions. Nevertheless, for both APEC and recombinant E. coli K-12 strains containing the tsh gene, it was only the whole bacterial cells and not the cell-free supernatants that could confer hemagglutinin activity. Our results provide insights into the expression, secretion, and proteolytic features of the Tsh protein, which belongs to the growing family of gram-negative bacterial extracellular virulence factors, named autotransporters, which utilize a self-mediated mechanism to achieve export across the bacterial cell envelope.     

15MnNbR钢制2000m3液化气球罐的焊接试验

针对新型球罐用钢12MnNbR进行了焊接材料试验、焊接裂纹试验和系列温度冲击试验，结果表明：目前市场上两种15MnNbR钢焊条均可用于该钢的焊接；在工程应用中，预热温度在125℃以上时一般不会出现冷裂纹；焊接线能量对焊缝的低温冲击韧性影响不大。本次试验对实际工程应用有一定的参考价值。     

Branch-skipped pipelined microprocessor

A new pipelined microprocessor has been designed. Branch instructions are detected in the early stage of the pipeline and branch target instructions are made available early enough to let the microprocessor skip all branch instructions. The average execution time per instruction is less than one machine cycle     

A simple recursive method for stationary receiver position estimation using GPS difference measurements

This paper presents a simple recursive method to estimate the position of a stationary receiver using the difference of Global Positioning System (GPS) pseudorange measurements. In contrast to conventional Differential GPS (DGPS), the proposed simple method uses the difference of pseudorange measurements corresponding to a single receiver itself without requiring a fixed station with known location. The use of difference measurements reduces the effects of the various noise terms involved in pseudorange measurements. According to the proposed method, the position of the receiver is estimated recursively using an optimal linear approximation of the pseudorange nonlinear equations. The effectiveness of the proposed method is demonstrated on the estimation of the position of a stationary receiver, and its performance is compared to the performance of a classical approach. The results show that the proposed method outperforms the classical approach.     

Remarks on receiving the C. Anderson Aldrich Award

In 2 patients digitalized with digoxin or betamethyldigoxin, postmortal glycoside concentrations were determined in 7 different skeletal muscle specimens by radioimmunoassay. In the same specimens, planimetric measurements of histochemical fibre types I and II were carried out. There were higher glycoside concentrations in predominantly type I fibre muscle biopsies.