Non‐destructive Examination of Loads in Regular and Self‐locking Spiralock® Threads through Energy‐resolved Neutron Imaging

Energy‐resolved neutron transmission imaging is utilised for in situ comparisons of strain distributions in fastened assemblies with regular and self‐locking Spiralock® female threads. The strain maps measured within torqued steel bolts indicate that for a Spiralock® thread, the load is distributed over a larger section of the fastener, making this type of thread more suitable for fastening of assemblies subject to transverse vibrations.     

Residue-specific mass signatures for the efficient detection of protein modifications by mass spectrometry

Currently available mass spectrometric (MS) techniques lack specificity in identifying protein modifications because molecular mass is the only parameter used to characterize these changes. Consequently, the suspected modified peptides are subjected to tandem MS/MS sequencing that may demand more time and sample. We report the use of stable isotope-enriched amino acids as residue-specific "mass signatures" for the rapid and sensitive detection of protein modifications directly from the peptide mass map (PMM) without enrichment of the modified peptides. These mass signatures are easily recognized through their characteristic spectral patterns and provide fingerprints for peptides containing the same content of specific amino acid residue(s) in a PMM. Without the need for tandem MS/MS sequencing, a peptide and its modified form(s) can readily be identified through their identical fingerprints, regardless of the nature of modifications. In this report, we demonstrate this strategy for the detection of methionine oxidation and protein phosphorylation. More interestingly, the phosphorylation of a histone protein, H2A.X, obtained from human skin fibroblast cells, was effectively identified in response to low-dose radiation. In general, this strategy of residue-specific mass tagging should be applicable to other posttranslational modifications.     

An analysis of cracks emanating from a circular hole in unidirectional fiber-reinforced composites

This paper presents an analytical study of cracks emanating from a circular hole in an off-axis unidirectional fiber-reinforced composite. A convenient and accurate method of analysis is formulated on the basis of conservation laws of elasticity and of fundamental relationships in anisotropic fracture mechanics. The problem is eventually reduced to a system of linear algebraic equations in mixedmode stress intensity factors. Superiority of the current analysis to other approaches in investigating the problem with very complicated crack geometry and material anisotropy is demonstrated when used in conjunction with any numerical method such as a finite element analysis. Mixed-mode stress intensity factors and the associated energy release rates in the crack problem are determined for the composites with various fiber orientations. Solutions for both single and double cracks emanating from the edge of a hole in the composites are presented also to illustrate the fundamental nature of the problem.     

Thrombophlebitis of the internal jugular vein secondary to pharyngitis

A case of septic thrombophlebitis of the internal jugular vein after pharyngitis is reported. Because of the common use and effectiveness of antibiotics against throat infections, this complication is now rarely seen. This condition has characteristic signs and symptoms, and a diagnosis can be obtained when the physician is aware of these characteristics. Radionuclide scan and Doppler effect flow studies of the internal jugular vein are useful diagnostic adjuncts. If recognized early and treated promptly with antibiotics, resolution is the rule. The literature has been reviewed.     

Multi-hop Clustering Based on Neighborhood Benchmark in Mobile Ad-hoc Networks

Large-scale mobile ad-hoc networks require flexible and stable clustered network structure for efficient data collection and dissemination. In this paper, a technique is presented to construct multi-hop clusters with balanced sizes, based on the neighborhood benchmark (NB) to quantify the connectivity and link stability of mobile nodes. By exploiting autonomous clusterhead selection and a specialized handshake process with the clusterheads, the nodes with highest NB scores are selected as clusterheads and all the clusters constructed are connected. The deviation of cluster sizes is kept small using a partial probability-based approach. Our technique generates highly stable multi-hop clusters with low overhead, and provides the flexibility of controlling the cluster radius adaptively for various network applications.     

A lossless smoothing algorithm for compressed video

Interframe coding techniques, such as those used in MPEG video, give rise to a sequence of encoded pictures whose sizes (in number of bits) differ by a factor of ten or more. Buffering is needed to reduce fluctuations in the rate at which video packets are sent to a network connection. We design and specify a lossless smoothing algorithm, characterized by three parameters: D (delay bound), X (number of pictures with known sizes), and H (lookahead interval). We prove a theorem which guarantees that, if K⩾1, the algorithm finds a solution that satisfies the delay bound. We present the algorithm's performance from a large number of experiments conducted using MPEG video traces. Lastly, we discuss algorithm implementation     

Superresolution image reconstruction from blurred observations by multisensors

Superresolution image reconstruction refers to obtaining an image at a resolution higher than that of the camera (sensor) used in recording the image. In this article, we present a joint minimization model with an objective function setup that comprises three terms: the data‐fitting term (DFT), the regularization term for the reconstructed image, and the observed low‐resolution images. An alternating minimization iterative algorithm is presented to reconstruct the image. We also analyze the alternating minimization iterative algorithm and show that it converges globally for H¹‐norm or total‐variation regularization that are functional for the reconstructed image. Numeric examples are given to illustrate the effectiveness of the joint minimization model and the efficiency of the algorithm. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13, 153–160, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10053     

Approximate polynomial preconditionings applied to biharmonic equations

Applying a finite difference approximation to a biharmonic equation results in a very ill conditioned system of equations. This paper examines the conjugate gradient method used with polynomial preconditioning techniques for solving such linear systems. A new approach using an approximate polynomial preconditioner is described. The preconditioner is constructed from a series approximation based on the Laplacian finite difference matrix. A particularly attractive feature of this approach is that the Laplacian matrix consists of far fewer non-zero entries than the biharmonic finite difference matrix. Moreover, analytical estimates and computational results show that this preconditioner is more effective (in terms of the rate of convergence and the computational work required per iteration) than the polynomial preconditioner based on the original biharmonic matrix operator. The conjugate gradient algorithm and the preconditioning step can be efficiently implemented on a vector super-computer such as the CDC CYBER 205.This work was supported in part by the Natural Sciences and Engineering Research Council of Canada Grant U0375; and in part by NASA (funded under the Space Act Agreement C99066G) while the author was visiting ICOMP, NASA Lewis Research Center.The work of this author was supported by an Izaak Walton Killam Memorial Scholarship.     

A formal methodology using attributed grammars for multiprocessing-system software development. I. Design representation

With the growing complexity of multiprocessing systems and distributed computing systems, there is an increasing need to provide a formal methodology for deriving a model to represent software design for the software development of these systems. The formal methodology presented in this paper uses attributed grammars, and extends formal methods commonly used in the definition of programming languages and compiler techniques for representing the design specification of software systems and validating the implementation. This model provides a common basis in the software development phases through automated design analysis, test-case generation, and validation of the software system. This paper covers the construction of the model for the design representation using attributed grammar and the analysis of the software system design based on the model.