Vacuum degassing of chromium-nickel-molybdenum steel at the Magnitogorsk Metallurgical Combine

The Magnitogorsk Metallurgical Combine has conducted a study of the effect of technological factors on the hydrogen content of chromium-nickel-molybdenum steel after vacuum degassing. It was established that the most important factor is the hydrogen content of the steel before the degassing operation. The study also determined the effects of the circulation coefficient, the duration of the degassing operation, and the vacuum used in the treatment. __________ Translated from Metallurg, No. 7, pp. 68–69, July, 2006.     

Understanding silica-supported metal catalysts: Pd/silica as a case study

Supported metal catalysts, particularly noble metals supported on SiO₂, have attracted considerable attention due to the importance of the silica–metal interface in heterogeneous catalysis and in electronic device fabrication. Several important issues, e.g., the stability of the metal–oxide interface at working temperatures and pressures, are not well-understood. In this review, the present status of our understanding of the metal–silica interface is reviewed. Recent results of model studies in our laboratories on Pd/SiO₂/Mo(1 1 2) using LEED, AES and STM are reported. In this work, epitaxial, ultrathin, well-ordered SiO₂ films were grown on a Mo(1 1 2) substrate to circumvent complications that frequently arise from the silica–silicon interface present in silica thin films grown on silicon.     

On the origin of strain hardening in glassy polymers

The influence of network density on the strain hardening behaviour of amorphous polymers is studied. The network density of polystyrene is altered by blending with poly(2,6-dimethyl-1,4-phenylene-oxide) and by cross-linking during polymerisation. The network density is derived from the rubber-plateau modulus determined by dynamic mechanical thermal analysis. Subsequently uniaxial compression tests are performed to obtain the intrinsic deformation behaviour and, in particular, the strain hardening modulus. At room temperature, the strain hardening modulus proves to be proportional to the network density, irrespective of the nature of the network, i.e. physical entanglements or chemical cross-links. With increasing temperature, the strain hardening modulus is observed to decrease. This decrease appears to be related to the influence of thermal mobility of the chains, determined by the distance to the glass-transition temperature (T−T_g).     

Performance study of iSCSI-based storage subsystems

iISCSI is emerging as an end-to-end protocol for transporting storage I/O block data over IP networks. By exploiting the ubiquitous Internet infrastructure, iSCSI greatly facilitates remote storage, remote backup, and data mirroring. This article evaluates the performance of two typical iSCSI storage subsystems by measuring and analyzing block-level I/O access performance and file-level access performance. In the file-level performance study, we compare file access performance in an NAS scheme with that in an iSCSI-based SAN scheme. Our test results show that Gigabit Ethernet-based iSCSI can reach very high bandwidth, close to that of a direct FC disk access in block I/O access. However, when the iSCSI traverses through longer distance, throughput relies heavily on the available bandwidth between the initiator and the target. On the other hand, the file-level performance shows that iSCSI-based file access (SAN scheme) provides higher performance than using NFS protocol in Linux and SMB protocol in Windows (NAS scheme). However, the advantage of using iSCSI-based file accesses decreases as the file size increases. The obtained experimental results shed some light on the performance of applications based on iSCSI storage.     

Inhibition of microbial growth in ready‐to‐eat food stored at ambient temperature by modified atmosphere packaging

This study was undertaken to develop a modified atmosphere package to control microbial growth in ready‐to‐eat (RTE) products stored at ambient temperature. Ethanol and/or limonene associated with modified atmosphere (CO₂ : O₂ : N₂ = 30% : 5% : 65%) was used to inhibit the growth of total air‐borne microorganisms and Escherichia coli in RTE products stored at 25°C. The results indicated that 0.05% ethanol vapour in the headspace was effective to inhibit the growth of air‐borne microorganisms and E. coli at 25°C for 72 h in a model study, and the effectiveness was related to ethanol content. Both 73 ppm limonene and 0.05% ethanol vapour enhanced the bacteriostatic effect of modified atmosphere in RTE sushi roll products, and no off‐flavour was detected using this formulated gas; however, no significant inhibitory effect was observed for RTE cold noodle products. This study concludes that combinations of carbon dioxide, ethanol or limonene vapours are effective to inhibit microbial growth in RTE food at ambient temperature, and the outcome may be due to the hurdle effect. Copyright © 2003 John Wiley & Sons, Ltd.     

Experimental and modeling approaches of MR behaviors under large step strains

Rheological properties of MR fluids under large step strain shear are presented in this paper. The experiments were carried out using a rheometer with parallel-plate geometry. Under the large step strain shear, MR fluids behave as nonlinear viscoelastic properties, where the stress relaxation modulus, G(t, γ), shows a decreasing trend with step strain. The experimental results indicate that G(t, γ) obeys time-strain separability. Thus, a mathematical form based on finite exponential serials is proposed to predict MR behavior. In this model, G(t, γ) is represented as the product of a linear stress relaxation, G(t), and the damping function, h(γ), i.e. G(t, γ)=G(t) h(γ). G(t) is simply represented as a three-parameter exponential serial and h(γ) has a sigmoidal form with two parameters. The parameters are identified by adopting an efficient optimization method proposed by Stango et al. The comparison between the experimental results and the model-predicted values indicates that this mathematical model can accurately predict MR behavior.     

Parallel algorithm for numerical self-consistent field theory simulations of block copolymer structure

An efficient algorithm is presented for numerically evaluating a self-consistent field theoretic (SCFT) model of block copolymer structure. This algorithm is implemented on a distributed memory parallel cluster in order to solve the SCFT equations on large computational grids. Simulation results are presented for a two-component molten mixture of a symmetric ABA triblock copolymer with an A homopolymer. These results illustrate a case in which simulating a large system is required to resolve features with a wide range of length scales.     

State of polarization changes: Classification and measurement

We propose a standardization procedure that provides a convenient, quantitative and reproducible laboratory-based method for measuring the state of polarization (SOP) fluctuations produced by polarization varying devices. This method is based on the SOP distributions generated by commercial polarization scramblers. We show that these devices generate distributions of the maximum change of the SOP (in a given sample time) that follow Rayleigh statistics, which scale linearly with scrambling frequency and the sample time. We use this procedure to measure the SOP fluctuations in a short length of coiled fiber subject to mechanical perturbations.     

Popular biorthogonal wavelet filters via a lifting scheme and its application in image compression

A technique using a lifting scheme is presented for constructing compactly supported wavelets whose coefficients are composed of free variables locating in an interval. An efficient approach-based wavelet for image compression is developed by selecting the coefficients of the 9-7 wavelet filter and associated lifting scheme. Furthermore, the rationalised coefficients wavelet filter that can be implemented with simple integer arithmetic is achieved and its characteristic is close to the well known original irrational coefficients 9-7 wavelet filters developed by A. Cohen et al. (Commun. Pure Appl. Maths., vol.45, no.1, p.485-560, 1992). To reduce the computational cost of image coding applications further, an acceleration technique is proposed for the lifting steps. Software and hardware simulations show that the new method has very low complexity, and simultaneously preserves the high quality of the compressed image.     

Handover and Uplink Power Control Performance in the 3.84 Mcps TDD mode of UTRA Network

In this article we consider the performance of the 3.84 Mcpstime-division duplex (TDD) mode of UTRA (Universal TerrestrialRadio Access) network. We emphasize two of the radio resourcemanagement algorithms, handover and uplink power control, whoserole in the overall system performance is studied extensively.First, a handover algorithm used in WCDMA (Wideband Code DivisionMultiple Access) standard is considered in a TDD-mode operation.This gives rise to a careful setting of different handoverparameters, and the evaluation of the effects to the systemperformance. Secondly, the specified uplink power controlalgorithm is considered. Since it is based on several user-mademeasurements which may involve both random and systematic errors acareful study about the suitability of the power control scheme iscarried out.