Deteriorated Heat Transfer Influence On the Stress-Strain State of SMR SCWR Fuel Bundles

The analysis of deteriorated heat transfer (DHT) influence on the stress-strain state of a perspective core of Small Modular Reactors with Supercritical Water (SMR SCWR) fuel assemblies is carried out, based on experimental and numerical data. Experimental data for 3- and 7-rod assemblies of 600 mm height with twisting spacer screws, on which deterioration heat transfer regimes were observed. The analysis of the stress-strain state was performed for two cases of temperature field. In the first variant, the temperature field is estimated using Computational Fluid Dynamics (CFD) with low-Re effects accounting, which allows obtaining the maximum temperature, but incorrectly estimates the axial profile. In the second case, an experimental profile with an averaged tangential temperature value is considered. Strength analysis is performed using the developed numerical-analytical mechanical model of the rod assembly. Obtained results make it possible to establish what is more important for assessing the safety of perspective reactors: a conservative estimate of the maximum wall temperature or its local distribution.

Comparative Thermal Degradation Behaviors and Kinetic Mechanisms of Typical Hardwood and Softwood in Oxygenous Atmosphere

In order to utilize woody biomass effectively for bioenergy and chemical feedstocks, the comparative thermal degradation behaviors and kinetic mechanisms of typical hardwood (beech wood) and softwood (camphorwood) were studied at various heating rates in air. The Kissinger-Akahira-Sunose approach combined with the Coats-Redfern approach was employed to estimate the kinetic triplet. Softwood degradation began and ended at lower temperatures than hardwood. Compared with softwood, the maximal reaction rate of hardwood was greater and occurred in the higher temperature region. Two decomposition regions were determined by the variation of activation energy, and the dividing point was α = 0.6 and α = 0.65 for hardwood and softwood, respectively. Moreover, the average activation energy of hardwood was larger than that of softwood during the whole decomposition process. The thermal degradation process occurring in region 1 was dominated by the Avrami-Erofeev and 3D diffusion models for hardwood and softwood, respectively. Furthermore, the kinetic modeling results showed good consistency between the experimental and simulated curves under 5, 15, 20, and 40 K/min. It is noted that the thermogravimetric experimental profile under 20 K/min was not used for estimating the kinetic triplet. Besides, the combustion performance of hardwood is superior to softwood under the same external conditions (heating rate and atmosphere).

COMPARISON OF AS, HG AND TL HIGH-FREQUENCY ELECTRODELESS LAMPS FOR DETECTION OF ENVIRONMENTAL POLLUTION

Nowadays, there is an increasing necessity to determine the concentration of different substances in the environment in low concentrations, as more and more attention is paid to environmental pollution. This work is devoted to the comparison of main characteristics of high-frequency electrodeless light sources with different fillings for their use in high precision atomic absorption analysers.The spectral line intensities and profiles were studied in special design light sources, manufactured at Institute of Atomic Physics and Spectroscopy, with arsenic, mercury and thallium filling. Special attention is devoted to the UV lines of 193.7 nm and 197.2 nm of As, 276.8 nm, 377.6 nm of Tl and 253.7 nm of Hg spectral lines. The intensities and profiles were measured by means of a Fourier transform spectrometer.The deconvolution procedure was implemented to obtain the real form of emitted profiles for further analysis, since in the case of low –pressure or cold plasma, the instrumental function is on the same order that experimental profile and it has to be taken into account. The instrumental function can distort the real spectral line shape significantly, for example, it changes the width of the spectral line that leads to the uncertainties in the determination of such important plasma parameters like temperature. The instrumental function can conceal a detailed structure of the spectral line, like the dip in the line center caused by the self-absorption (self-reversal) and characterizing the radiation trapping.The integrated areas, values of self-absorption, and other parameters were obtained and compared for all fillings as a function of working regimes.

Study of 14N(ρ,γ)15O resonance reaction at Eplab= 278 keV

An implanted target (14N on Ta) is prepared and characterized via surface and bulk characterization processes. The depth profile of the implanted ions is obtained experimentally by populating a narrow resonance state of 15O through 14N(ρ,γ) reaction induced with a laboratory proton energy of 278 keV. The experimental profile is then compared with devoted simulations to under- stand the locations of the implantated ions in the lattice structure. Later, the lifetimes of a few excited states of 15O, relevant for applications in astrophys- ical scenario, have been determined using Doppler Shift Attenuation Method(DSAM).

ITC and SPR Analysis Using Dynamic Approach

ABSTRACTBiophysical techniques such as Isothermal Calorimetry (ITC) and Surface Plasmon Resonance (SPR) are routinely used to ascertain the global binding mechanisms of protein-protein or protein-ligand interaction. Recently, Dumas etal, have explicitly modelled the instrument response of the ligand dilution and analysed the ITC thermogram to obtain kinetic rate constants. Adopting a similar approach, we have integrated the dynamic instrument response with the binding mechanism to simulate the ITC profiles of equivalent and independent binding sites, equivalent and sequential binding sites and aggregating systems. The results were benchmarked against the standard commercial software Origin-ITC. Further, the experimental ITC chromatograms of 2’-CMP + RNASE and BH3I-1 + hBCLXL interactions were analysed and shown to be comparable with that of the conventional analysis. Dynamic approach was applied to simulate the SPR profiles of a two-state model, and could reproduce the experimental profile accurately.

Spectroscopic Features of Raman Gain Profiles in Single-Mode Fibers Based on Silica Glass

The spectroscopic analysis of the frequency distribution of the amplification of optical radiation due to the Raman effect (Raman gain profile) in single-mode fibers based on silica glass has been carried out in the region of Stokes frequency shifts from 0 to 1400 cm−1. The Raman gain profiles are determined from the experimental spectra of spontaneous scattering for widespread fibers, namely for pure SiO2, GeO2, P2O5, and TiO2 doped fibers. The analytic expressions of the Raman gain profiles are given. They are obtained, by using the Gaussian decomposition by means of 11–12 modes, and the experimental profile is approximated with an accuracy of not less than 0.3%. The decomposition results are analyzed in terms of the fundamental oscillatory dynamics of molecular nanocomplexes in amorphous glass, as well as in the application aspect of the modeling of photonics devices. Examples of the proposed method applications are presented for the analysis of noise parameters of the fiber Raman amplifiers and for the generation bandwidth in fiber Raman lasers.

Second Law Analysis of Different Channel Geometries for Micro-Mixing

Micro-mixing in different channel geometries may increase entropy generation and lead to improved efficiency of fluid mixing. The entropy generation rate corresponds to irreversibility due to the heat transfer and viscous effects in fluid flow through a channel. The objectives of this study are to validate the entropy generation rate of three expansion/contraction geometries [1] by using an analysis based on the Second Law of Thermodynamics (SLT) numerically and to study how entropy generation rate changes by placing flow obstacles in the channel. The geometries presented are not unique. In this paper the focus is on using CFD combined with the SLT as a tool to explore the effectiveness of micro-mixers. The entropy generation field in the expansion/contraction region between a 100 micrometer wide and a 200 micrometer wide rectangular micro-channel was analyzed using computational fluid dynamics (CFD) ANSYS-Fluent, and compared with the experimental results from Saffaripour et al. [1]. The numerical velocity profiles in the fully developed region of the channel in the flow direction and normal to flow direction were compared with experimental profile [1], and determined to be in agreement with the experimental profile. Using CFD, the entropy generation rates were determined for combinations of channel expansion/contraction geometry and the presence/lack of flow obstacles. The results presented here show that flow obstacles, which generally lead to better mixing, also lead to higher entropy generation rates.

Experimental and Numerical Analysis of Residual Stress in Cast Aluminum Alloy after FSP Process

The effect of FSP modification of cast aluminum alloy AlSi9Mg on residual stress are presented. The numerical results are compared with the residual stresses experimentally measured by the trepanation method. Experimental results show that the residual tensile stresses are higher on the advancing side than on the retreating side. The simulation successfully captures the asymmetric behavior of the residual stress profile, and the predicted maximum residual stress values show relatively good agreement with the experimental values. The simulated profile, however, is more narrow than the experimental profile, yielding a smaller region of residual tensile stresses around the process zone than experimentally observed

The Profile Curve of Tooth-Shaped Roller Influence on the Rolling Force of Corrugated Web Rail

The corrugated web rail is a special kind of rail structure. Horizontal roller of rolling the corrugated web rail is named as tooth-shaped roller because its shape is close to straight tooth gear. The profile curve of tooth-shaped roller has great influence on the finish product quality , the rolling process and the rolling force of the corrugated web. In this paper, profile curve of tooth-shaped roller of rolling corrugated web rail was designed. FEM model of rolling corrugated web rail was established and the rolling process was simulated by the software ANSYS/LS-DYNA. In the condition of the same reduction and the same rolling speed, the rolling force was compared of experiment profile curve with the designed profile curve. According to the analysis results, the rolling force of the designed profile curve is significantly smaller than that of experimental profile curve. Therefore, it is necessary to optimize profile curve of the tooth-shaped roller to decrease the rolling force.