Stress relaxation in the interface between creep particle and elastic matrix-strengthening mechanism

The effect of a power law creep particle on interface behavior between the particle and elastic matrix is investigated by stress analysis. Using the results obtained through the stress analysis, the forces due to interaction of an applied stress and stress concentration with an edge dislocation are determined. The direct interaction between the edge dislocation and the creeping particle is studied under fully relaxed stress conditions. Through the investigation the following results are derived. Stress relaxation in the interface can be caused by power law creep along or by diffusion, or a combination of both mechanisms. The degree of stress relaxation caused by diffusion can be defined in terms of the relaxation time for both boundary diffusion and volume diffusion. The amount of stress relaxation caused by the power law creep particle is characterized by the quantity ₂ which is a function of Γ₀ = 2(1/√3)^{1 + m} × (σ_∞/2μ)^m(σ₀/σ_∞t^m), where m is strain rate hardening exponent, σ_∞ is applied stress, μ is the shear modulus, σ₀ is the material constant of the power law creep particle, and t is elapsed time. The value ₂ = 1.0 corresponds to the fully relaxed condition and ₂ = −0.6 corresponds to the initial state. The time to reach a fully relaxed condition is very sensitive to the strain rate exponent, with the smaller m values leading to longer times. The stress state of complete relaxation in the elastic matrix is equivalent to the solution of a void in an elastic matrix superposed on the solution of positive surface traction on the void. This result is identical to that obtained by Srolovitz et al. [Acta. Metall.32, 1979 (1984)]. When the stress is completely relaxed in the particle, all stress components (σ_r, σ_θand σ_rθ) are relaxed, while in the matrix relaxations are observed only for σ_rand σ_θ. The critical resolved shear stress and critical stress to climb the dislocation in the neighborhood of the particle exceed the Orowan stress. Also, the particle attracts the dislocation. Therefore the strengthening of a power law creep particle in an elastic matrix is caused by the Orowan mechanism and by attraction of the dislocation.     

To secure XML documents with the extension function of XSLT

XSLT is a very popular and flexible language for transforming XML documents which provides a powerful implementation of a tree‐oriented transformation language for transmuting instances of XML using a single vocabulary into a desired output. In this paper, we propose a processing model that enables the XSLT processor to encrypt and decrypt XML documents. The details of the implementation are presented. Our model supports a more general encryption scope than previous models. The implementation and experimental results demonstrate the practicality of the proposed model. Copyright © 2006 John Wiley & Sons, Ltd.     

Orderly stimulation of skeletal muscle motor units with tripolarnerve cuff electrode

An electrical nerve stimulation technique, using single tripolar electrode, was shown to be capable of recruiting motor units according to their size, while allowing simultaneous but independent control of firing rate in the active units. Test paradigms consisting of established fundamental physiological concepts of soleus-gastrocnemius architecture, motor units conduction velocity, firing rate behavior of motor units of different sizes, and their susceptibility to fatigue were employed to validate the technique and demonstrate its utility as a basic and applied research tool.     

A drag-link drive of mechanical presses for precision drawing

The augmented Lagrange multiplier method has been used to synthesize the dimensions of a drag-link drive of mechanical presses for precision drawing. The objective functions include the maximum normal force on the guide, mean mechanical advantage, variance of the drawing velocity, etc. The constraints include the working velocity for drawing, variance of the working velocity for precision drawing, time ratio, etc. Based on the concept of kinematic coefficients, a method is proposed to provide suitable initial guesses of the optimization. The drag-link drive thus synthesized has performance superior to an existing press for precision drawing.     

Design of a performance enhanced traceback algorithm for theViterbi decoder

The authors propose an efficient traceback scheme for the parallel hardware implementation of the Viterbi algorithm. Compared to the conventional Viterbi algorithm, where output is selected arbitrarily when multiple survivor paths exist, the proposed algorithm decides decoding output by analysing the survivor paths of consecutive tracebacks. Experimental results show that the proposed algorithm exhibits improved error-correction capability compared to the existing algorithms     

Reflex sympathetic dystrophy: is the immune system involved?

OBJECTIVE: Evaluation of immune system function in patients with reflex sympathetic dystrophy (RSD). DESIGN: Survey on blood samples obtained from RSD patients and from a randomly selected control group. The lymphocyte populations (T, B, NK cells), and the activated T cells (CD25, and HLA-Dr-positive CD4 and CD8 cells) were analyzed by flow cytometry with dual-color direct immunofluorescence after whole-blood lysis. Clinical chemistry parameters were analyzed in additional serum samples. SETTING: Tertiary care center (outpatient rehabilitation clinic). SUBJECTS: Thirteen patients (nine women) with RSD and a control group of 21 healthy individuals. MAIN OUTCOME MEASURES: The results of the flow cytometry analysis of RSD patients were related to those of the control subjects. Means were analyzed, and confidence intervals for differences of the means were calculated. The means of the clinical chemical analysis were related to local reference values. RESULTS: The flow cytometry analysis did not differ between RSD patients and healthy controls. Although in some patients an individual parameter of clinical chemical analysis differed from its reference value, all of the mean values were within reference limits. Stratification on medications with immunomodulatory effects and on probability of a definite diagnosis of RSD had no influence on the results. CONCLUSION: No association between immunologic indices and RSD was found. This finding is relevant, because recent theories stress that it is not the sympathetic nervous system but a local inflammatory reaction that is fundamental in the pathogenesis of RSD. The results of this study do not support this theory.     

High-performance simulations of turbulent boundary layer flow using Intel Xeon Phi many-core processors

The Journal of Supercomputing - Direct numerical simulations (DNS) of turbulent flows have increasing importance because they not only provide fundamental understanding of turbulent flows but also...