Determination of the rheological properties of whole blood by the nonstationary method of pulsed changing of the rate of shear

Problems associated with the use of the nonstationary method of pulsed changing of the rate of shear for the measurement of important viscoplastic properties of whole blood — the critical shear stress τ₀ and the plastic viscosity μ_p — are considered. The indicated method was compared to the method of stationary rheometry. It is shown that the blood-flow curve obtained by this method, unlike that obtained by the stationary method, characterizes a viscoplastic medium. To calculate the parameters of this medium exactly, it is necessary to take into account the dependence of the rate of shear on the above-indicated parameters. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 176–179, September–October, 2005.     

Coating of bioactive glass 13-93 fibres with biomedical polymers

The aim of this study was to coat bioactive glass 13-93 fibres with biomedical polymers. Two methods were used to coat the fibres, namely, dipping and pulling through a viscous solution. With both methods the fibres were successfully coated. Dipping was preferred for thin fibres (20–50 μm) and with this method approximately 2–5 μm thin polymer coat was obtained on the fibre surface. Pulling through viscous solution was preferred for thicker fibres (150–250 μm) and with this method approximately 10–30 μm polymeric coat was obtained. Coating the fibres enables further processing of the bioactive glass fibres and improves the mechanical properties and processibility of fibres.     

Waveguide-dielectric resonator method for accurate measurement of parameters of materials at high frequencies

The theory is given, with an analysis and various examples, of the practical implementation of a method for measuring the relative permittivity ɛ^*=ɛ′−iɛ″ of materials in the 0.5–26-GHz frequency range. The results and experimental errors are given of measurements of ε′ in the range 2–200 and of tanδ in the range from 5·10⁻⁵ to 2·10⁻². Translated from Izmeritel'naya Tekhnika, No. 6, pp. 62–66, June, 1999.     

Study of the dielectric parameters of aluminium ore bauxite of Mainpat area of Chhattisgarh at X-band frequency

A simple method for measuring the dielectric parameter of materials in the form of powders at microwave frequencies is suggested. Measurement of the permittivity ε′ and ge″ at 9·967 GHz on powder samples of the aluminum ore bauxite gives interesting results. It is found that ε′ and ε″ increases with packing densities (δ ). Further ε′ and ε″ also depend upon the percentage of Al₂O₃. These results show that the values of ε′ and ε″ can be used to set certain basic values for minability of the ore for a particular sample. Conductivities (σ) and relaxation (τ) are also calculated in the present studies     

Microwave measurements of the complex permittivities and permeabilities of magnetodielectrics

A method is proposed for determining complex permittivities ɛ* and permeabilities μ* by analyzing the interaction of a plane electromagnetic wave with a plane-parallel sample in free space. Results of the method are presented. Translated from Izmeritel'naya Tekhnika, No. 4, pp. 51–52, April, 1996.     

Determination of the size of the fatigue prefracture zone by the method of phase-shifting interferometry

We consider a new method for determining the size of the fatigue prefracture zone (a new structural-mechanical parameter d* of constructional materials) by the method of phase-shifting interferometry, based on the results of a comparative analysis of the surface profile of metallic specimens in the neighborhood of a constructional stress concentrator prior to and after a certain quantity of loading cycles. To obtain interferograms in laser light, we applied a Twyman–Green interferometer. Using these results, we determined the 3-D distribution of plastic strains near the concentrator vertex, which enabled us to establish that d* = 256–268 μm for low-carbon 08kp steel at a load ratio R = 0.1. The obtained value of this parameter is in good agreement with data obtained by other methods.     

Measurement of dielectric properties of high-absorption materials at microwave frequencies

A method is proposed for measuring the dielectric constant ε′ and dielectric loss ε″ of high-absorption dielectric materials by measuring the reflection of electromagnetic radiation with the aid of an adjustable quarter-wave matching plate of nonabsorbing material close to the dielectric surface. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 45–47, May, 1999.     

Controllable synthesis and morphology-dependent microwave absorption properties of iron nanocrystals

Iron nanospheres, nanoflakes and nanofibers were synthesized via a simple pyrolysis method. When the pyrolysis temperature increased from 523 to 623 K and the flow rate of Ar carrier gas maintained at 100 sccm, the as-prepared iron nanocrystals showed a morphology evolution from isotropic nanospheres to isotropic nanofibers. The phase structures and morphologies of the composite were characterized by X-ray diffraction and scanning electron microscopy. The complex permittivity (ε′ − jε″) and permeability (μ′ − jμ″) of these composites were measured using the transmission/refection coaxial line method in the frequency range of 1–18 GHz by a vector network analyzer. The iron nanofibers exhibited superior microwave absorbing properties compared to iron nanoparticles and nanoflakes. The optimal reflection loss (RL) reached −17.8 dB at 9.9 GHz with a layer thickness of 2.0 mm. The RL below −10 dB can be obtained in the frequency range of 7.3–11.7 GHz. Considering the low cost and high efficiency; the iron nanofibers are favorable for application as microwave absorber.     

Diffusion of erbium in silicon

Diffusion of erbium in silicon has been investigated by the electric method. The erbium diffusion coefficient in the temperature range 1150–1250 °C increases from 1.4×10⁻¹³ to 6.2×10^{− 13} cm²·s⁻¹. The values obtained for the diffusion coefficient of erbium in silicon are in good agreement with data obtained by the method of tagged atoms. Pis’ma Zh. Tekh. Fiz. 24, 68–71 (January 26, 1998)     

Synthesis of SrCrO<Subscript>4</Subscript> nanostructures by onion inner-coat template and their optical properties

This paper describes a bio-template method of the squama inner coat of onion for preparing the SrCrO₄ nanostructures including nanospheres, nanorods and dumbbell-shaped superstructure. The method is able to make SrCrO₄ nanoparticles with average diameters in the range of 90–170 nm, SrCrO₄ nanorods with length in the range 0·70–2 μm, width in the range of 80–180 nm, and SrCrO₄ dumbbell-shaped superstructure with length in the range 10–14 μm. The dumbbell-shaped superstructures are assembled by many SrCrO₄ nanowires with length in the range 10–14 μm and width in the range 30–50 nm. The products were characterized by transmission electron microscope, powder X-ray diffraction, UV-Vis spectroscopy and luminescence spectrophotometer. A possible formation mechanism was also proposed. In the preparation, the SrCrO₄ nanostructures were synthesized at room temperature without any surfactants. This new bio-template method will have potential applications in preparation of the nanoscale materials with different morphologies.     

The effectiveness of using one variant of the finite-element method for solving nonlinear nonstationary heat-conduction problems

It is established that the use of a previously proposed variant of the finite-element method for solving nonlinear nonstationary heat-conduction problems is efficient (in the sense of computer time expenditures) when the half-width of the band β of the resulting matrix in the system of linear algebraic equations does not exceed a certain value of β_cr. As a result of a numerical experiment for an axially symmetric case we obtain β_cr ≈ 47, which demonstrates the effectiveness of this variant of the finite-element method for solving a wide range of practical problems of heat-conduction theory. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 2, pp. 284–289, March–April, 1997.     

Computation of free-surface flows and fluid–object interactions with the CIP method based on adaptive meshless soroban grids

The CIP Method [J comput phys 61:261–268 1985; J comput phys 70:355–372, 1987; Comput phys commun 66:219–232 1991; J comput phys 169:556–593, 2001] and adaptive Soroban grid [J comput phys 194:57–77, 2004] are combined for computation of three- dimensional fluid–object and fluid–structure interactions, while maintaining high-order accuracy. For the robust computation of free-surface and multi-fluid flows, we adopt the CCUP method [Phys Soc Japan J 60:2105–2108 1991]. In most of the earlier computations, the CCUP method was used with a staggered-grid approach. Here, because of the meshless nature of the Soroban grid, we use the CCUP method with a collocated-grid approach. We propose an algorithm that is stable, robust and accurate even with such collocated grids. By adopting the CIP interpolation, the accuracy is largely enhanced compared to linear interpolation. Although this grid system is unstructured, it still has a very simple data structure.     

Experimental estimate of self-irradiation of building bricks due to incorporated radionuclides

A method is described for experimentally determining the dose rate created in building bricks by incorporated natural radionuclides. It was established using the thermoluminescence dosimetry method that the measured dose rate depends on the detector thickness, the mass of the ceramic product investigated, and the irradiation geometry. The contributions to the measured dose of weakly penetrating α and β radiation and hard ψ radiation are separated, the ratio between them depending on the experimental conditions. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 62–66, July, 1996.     

Dispersion free analysis of acoustic problems using the alpha finite element method

The classical finite element method (FEM) fails to provide accurate results to the Helmholtz equation with large wave numbers due to the well-known “pollution error” caused by the numerical dispersion, i.e. the numerical wave number is always smaller than the exact one. This dispersion error is essentially rooted at the “overly-stiff” feature of the FEM model. In this paper, an alpha finite element method (α-FEM) is then formulated for the acoustic problems by combining the “smaller wave number” model of FEM and the “larger wave number” model of NS-FEM through a scaling factor ${a\in [0,1]}The classical finite element method (FEM) fails to provide accurate results to the Helmholtz equation with large wave numbers due to the well-known “pollution error” caused by the numerical dispersion, i.e. the numerical wave number is always smaller than the exact one. This dispersion error is essentially rooted at the “overly-stiff” feature of the FEM model. In this paper, an alpha finite element method (α-FEM) is then formulated for the acoustic problems by combining the “smaller wave number” model of FEM and the “larger wave number” model of NS-FEM through a scaling factor a ? [0,1]{a\in [0,1]} . The motivation for this combined approach is essentially from the features of “overly-stiff” FEM model and “overly-soft” NS-FEM model, and accurate solutions can be obtained by tuning the α-FEM model. A technique is proposed to determine a particular alpha with which the α-FEM model can possess a very “close-to-exact” stiffness, which can effectively reduce the dispersion error leading to dispersion free solutions for acoustic problems. Theoretical and numerical studies shall demonstrate the excellent properties of the present α-FEM.     

Metrological support for measurement of microminiature dimensions using theoretical models,measures, and natural constants

A “standardless” method is proposed for measurement of small dimensions; the method uses the speed of light as a natural physical constant. Translated from Izmeritel'naya Tekhnika, No. 11, pp. 15–18, November, 1996.     

Measurement of the instantaneous frequency of broadband signals in a short observation interval

A high-speed method of estimating the instantaneous frequency of broadband signals with slowly varying amplitude and phase using a short sample in real time is proposed, and results of numerical modeling of the measurement procedure are presented. The speed of response and noise immunity of the method is compared with the existing method, based on the theory of signal “splitting.” It is shown that in both methods it is possible to use recurrence relations, which considerably reduce the measurement time. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 50–54, February, 2008.     

Origin of the αc relaxation in poly(ethylene-terephthalate) by thermally stimulated currents

The thermally stimulated depolarization currents of poly (ethylene-terephthalate) electrets with a reduced degree of crystallinity (≃4%), corona-charged at polarization temperatures between 65 and 100 °C, show a heteropolar α^* relaxation placed between the α relaxation (heteropolar) and the ρ relaxation (homopolar). This α^* relaxation is associated with a uniform mechanism and has been observed in the discharge of electrets with shorted evaporated electrodes, which have been formed using the windowing polarization method at polarization temperatures between 76 and 79 °C. The intensity and position of α^* depend on the degree of crystallinity and the morphology. The application of the method of thermal stimulation by steps, which leads to a gradual crystallization of the sample, shows that the α_c relaxation of crystalline PET has its origin in α^*.     

Study on hydration of Portland cement with fly ash using electrical measurement

The electrical resistivity method was used for measuring the electrical resistivity of cement paste incorporating with fly ash. The study found that the bulk electrical resistivity ρ(t) was a function of the solution electrical resistivity ρ0(t) and porosity Φ. A two-component model was proposed, in which ρ(t) was dominated by ρ0(t) at the early period of hydration and dominated by Φ at a later period. The porosity formation curve was derived from the 2-point method. A logarithmic equation ρ(t)=K^*In(t/t₀) was proposed to express the electrical resistivity development with time after hardening, where K represents the rate of hydration, and the pastes with fly ash had a lower K. The setting times and compressive strengths were tested and the results were compared with the electrical properties.     

Performance measures for the socio-economic impact of government spending on R&D

Summary The aims of this paper are to summarize Canadian government programs pertaining to research and development (R&D) and R&D support programs, and to propose a method for analyzing their socio-economic impact. The programs under investigation include: • Canada Research Chairs • Canada Millennium Scholarship Foundation • Canada Foundation for Innovation • Technology Partnerships Canada (TPC) • Industrial Research Assistance Program (IRAP) • Natural Sciences and Engineering Research Council (NSERC) • Social Sciences and Humanities Research Council (SSHRC) • Canada Institutes of Health Research (CIHR) • Canadian Institute of Advanced Research (CIAR) • Pre-Competitive Advanced Research Networks (PRECARN) • Networks of Centres of Excellence     

Uncertainty of Thermal Diffusivity Measurements by Laser Flash Method

The laser-pulse method is a well-established nonsteady-state measurement technique for measuring the thermal diffusivity, a, of solid homogeneous isotropic opaque materials. BNM-LNE has developed its own bench based on the principle of this method in which the thermal diffusivity is identified according to the “partial time moments method.” Uncertainties of thermal diffusivity by means of this method have been calculated according to the ISO/BIPM “Guide to the Expression of Uncertainty in Measurement.” Results are presented for several cases (Armco iron, Pyroceram 9606) in the temperature range from 20 to 800°C. The relative expanded (k = 2) uncertainty of the thermal diffusivity determination is estimated to be from ±3 to ±5%, depending on the material and the temperature. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.