The influence of parent austenite characteristics on the intervariant boundary network in a lath martensitic steel

Journal of Materials Science - The influence of the parent austenite deformation state on the intervariant boundary network (i.e., population, plane orientation, and connectivity) of a lath...     

关于图的L(d1,d2)-标号问题

图的L(2,1)-标号问题是由频率分配问题归结而来,本文研究作为L(2,1)-标号问题的推广的L(d_1,d_2)-标号问题。首先定义了顶点2-着色,2-色数及其它有关概念,给出了2-色数的上界。然后得出了λ_(d_1,d_2)(G)与δ(G)和Δ(G)的一般关系。最后得出了一般图与平面图的λ_(d_1,d_2)(G)的上界。     

The influence of natural reinforcement fibres on insulation values of earth plaster for straw bale buildings

This work aimed to measure the thermal conductivity of some natural plaster materials that could be used for straw bale buildings. Thermal conductivity is very important to determine the insulation value and other thermal parameters for natural plaster materials. Plaster materials consisted of soil, sand and straw. Straw is used as a reinforcement fibre for plaster. Three types of fibres were used such as wheat straw, barley straw and wood shavings. The results indicated that the thermal conductivity of all materials decreased with increasing straw fibre content and decreased with increasing sand content. The straw fibres have greater effect on the change of thermal conductivity than the effect of sand. The results also revealed that plaster reinforced by barley straw fibres has the highest values of thermal insulation.     

The influence of the electron energy distribution on the low pressure chlorine discharge

A global (volume averaged) model of a chlorine discharge is applied to explore the effect of the electron energy distribution on the plasma parameters such as particle densities and reaction rates. The effective electron temperature increases, the densities of charged particles decrease and the total reaction rate for the creation of Cl⁻ decreases as the electron energy distribution function is varied from approximately bi-Maxwellian to Maxwellian to Druyvesteyn distribution, while the applied power is kept fixed. The relative contribution of electron impact dissociation to the creation of the neutral Cl atom increases significantly as the electron energy distribution is varied from approximately bi-Maxwellian to Maxwellian to Druyvesteyn distribution, while the loss processes for Cl are nearly independent of the electron energy distribution.     

The influence of the energy distribution of workplace fields on neutron personal dosemeter reading

Variations in the energy dependence of response of neutron personal dosemeters cause systematic errors in the readings obtained in workplace fields. The magnitude of these errors has been determined theoretically by folding measured and calculated workplace energy distributions with dosemeter response functions, to determine the response of a given personal dosemeter in that field. These results have been analysed with consideration of the dosemeter response to various calibration spectra, and with reference to different workplaces. The dosemeters in the study are discussed in terms of the workplaces for which they can be suitably calibrated. Deficiencies in the published neutron energy distributions are identified.     

The influence of mean stress and amplitude distribution on random load fatigue crack growth

Random load fatigue crack growth tests have been conducted on a low alloy steel, Q1N, under varying conditions of mean stress and probability density function (pdf). The results show that Q1N is insensitive to the pdf, but that a mean stress effect is measurable. This mean stress dependence is not found in constant amplitude tests on the same material.A modified form of the Fonnan equation was found to fit the data adequately.     

The influence of isoclinics on photoelastic studies of the stress distribution around a crack tip

A photoelastic investigation of the stresses around edge cracks in a tensile field, is described. The influence of isoclinics on the accuracy of stress intensity coefficients is demonstrated, and the results are compared with theoretical values obtained using the collocation method.     

Constructing exact tolerance intervals for the exponential distribution based on record values

Recently, with the wide application of tolerance intervals (TIs), especially in quality management, the construction of TIs has attracted increasing attention. However, TIs applied to record data have not been well established as they have been for complete data. In many industrial stress tests, only record data are stored instead of complete data, which leads to the fact that the developments of methods based on record data are as important as those based on complete data. In this paper, we propose the exact two-sided TIs for the exponential distribution based on record values from the frequentist and Bayesian perspectives. The accuracy of each type of TIs is quantified. The results show that the Bayesian approach is superior to the frequentist approach in terms of the accuracy. A real data example is used to illustrate the constructions and implementations of the proposed TIs.     

The influence of particle-size distribution on critical state behavior of spherical and non-spherical particle assemblies

This paper presents an investigation into the effects of particle-size distribution on the critical state behavior of granular materials using discrete element method (DEM) simulations on both spherical and non-spherical particle assemblies. A series of triaxial test DEM simulations examine the influence of particle-size distribution (PSD) and particle shape, which were independently assessed in the analyses presented. Samples were composed of particles with varying shapes characterized by overall regularity (OR) and different PSDs. The samples were subjected to the axial compression through different loading schemes: constant volume, constant mean effective stress, and constant lateral stress. All samples were sheared to large strains to ensure that a critical state was reached. Both the macroscopic and microscopic behaviors in these tests are discussed here within the framework of the anisotropic critical state theory. It is shown that both OR and PSD may affect the response of the granular assemblies in terms of the stress–strain relations, dilatancy, and critical state behaviors. For a given PSD, both the shear strength and fabric norm decrease with an increase in OR. The critical state angle of shearing resistance is highly dependent on particle shape. In terms of PSD, uniformly distributed assemblies mobilize higher shear strength and experience more dilative responses than specimens with a greater variation of particle sizes. The position of the critical state line in the e–p′ space is also affected by PSD. However, the effects of PSD on critical strength and evolution of fabric are negligible. These findings highlight the importance of particle shape and PSD that should be included in the development of constitutive models for granular materials.     

The influence of surface structures on sputtering: Angular distribution and yield from faceted surfaces

Solid surfaces subject to energetic particle bombardment generally develop characteristic structures, which may significantly change the total and differential sputtering yield. The change is due to two competing effects, a yield-increase by an enhanced effective projectile incidence angle, and a yield-reduction by recapture of obliquely ejected particles. Both effects have been included in calculations of the sputtering yields from faceted surfaces in the regime where the plane surface yield follows a cos^−v dependence on the incidence angle. Except at very low energies, the total sputtering yield is always increased by faceting. The angular distribution function is mainly influenced at large polar angles and may significantly deviate from that of the corresponding flat surface. This has important consequences both in comparisons between experimental and theoretical distribution functions as well as in applications such as thin film production, plasma contamination, secondary ion mass spectrometry etc. EURAT0M Association.     

The influence of variable operating conditions upon the general multi-modal Weibull distribution

For the design spectrum prediction that should be realized within the expected service life, the influence of variable loading conditions is of paramount importance. Further, the results of the measurements must be properly extrapolated and the scatter of loading spectra has to be determined to assure reliable service life prediction. To model load ranges, a general multi-modal Weibull distribution function has recently been proposed. Until now it has been verified only for fixed operating conditions. The scope of this article is to prove that the same distribution model holds for the case of variable operating conditions, too. The influence of variable operating conditions upon the distribution function is demonstrated by a few examples attained by analysing loads acting upon a structure of a fork-lift.     

The influence of bile salts on the distribution of simvastatin in the octanol/buffer system

Abstract

Introduction: Distribution coefficient (D) is useful parameter for evaluating drugs permeability properties across biological membranes, which are of importance for drugs bioavailability. Given that bile acids are intensively studied as drug permeation-modifying and -solubilizing agents, the aim of this study was to estimate the influence of sodium salts of cholic (CA), deoxycholic (DCA) and 12-monoketocholic acids (MKC) on distribution coefficient of simvastatin (SV) (lactone [SVL] and acid form [SVA]) which is a highly lipophilic compound with extremely low water solubility and bioavailability.

Methods: LogD values of SVA and SVL with or without bile salts were measured by liquid–liquid extraction in n-octanol/buffer systems at pH 5 and 7.4. SV concentrations in aqueous phase were determined by HPLC-DAD. Chem3D Ultra program was applied for computation of physico-chemical properties of analyzed compounds and their complexes.

Results: Statistically significant decrease in both SVA and SVL logD was observed for all three studied bile salts at both selected pH. MKC exerted the most pronounced effect in the case of SVA while there were no statistically significant differences between observed bile salts for SVL. The calculated physico-chemical properties of analyzed compounds and their complexes supported experimental results.

Conclusions: Our data indicate that the addition of bile salts into the n-octanol/buffer system decreases the values of SV distribution coefficient at both studied pH values. This may be the result of the formation of hydrophilic complexes increasing the solubility of SV that could consequently impact the pharmacokinetic parameters of SV and the final drug response in patients.     

The influence of surface diffusion on surface roughness and component distribution profiles during deposition of multilayers

The kinetic processes taking place on the surface and influencing the depth distribution of components during deposition of multilayers are considered by proposed kinetic model. The depth distribution of components in growing structure, broadening of interfaces between layers and shape of concentration peaks of multilayers are analyzed with respect of evolution of surface roughness during deposition. Surface roughness depends on adsorption rate and on surface diffusion. In presented model, the process of surface diffusion is subdivided into up-diffusion and down-diffusion. It is shown that atomic fluxes of up-diffusion and down-diffusion do not compensate each other even in the case of equal diffusion coefficients as they depend on coverage of different monolayers. Down-diffusion results in smoother surface, in contrary, up-diffusion makes it rougher. It is quantitatively shown by kinetic modeling that with increase of down-diffusion the amplitude of concentration peaks of components increases, the broadening of interface between layers decreases and concentration peaks become asymmetrical. The asymmetry of concentration peaks is found even in the case of equal diffusion coefficients of different components. At different diffusivity of components, the asymmetry is following: the concentration peaks of heavy-component (less diffusivity) show enhanced trailing tails on the back profile side (for light-component on the contrary). Up-diffusion results in increase of surface roughness and broadening of interface between layers. The quantitative functions of surface roughness on ratio of up- and down- diffusion coefficients are calculated and analyzed.     

The combined influence of grain size distribution and dislocation density on hardness of interstitial free steel

Understanding the relationship between microstructure features and mechanical properties is of great significance for the improvement and specific adjustment of steel properties. The relationship between mean grain size and yield strength is established by the well-known Hall-Petch equation. But due to the complexity of the grain configuration within materials, considering only the mean value is unlikely to give a complete representation of the mechanical behavior. The classical Taylor equation is often used to account for the effect of dislocation density, but not thoroughly tested in combination with grain size influence. In the present study, systematic heat treatment routes and cold rolling followed by annealing are designed for interstitial free(IF) steel to achieve ferritic microstructures that not only vary in mean grain size, but also in grain size distribution and in dislocation density, a combination that is rarely studied in the literature. Optical microscopy is applied to determine the grain size distribution. The dislocation density is determined through XRD measurements. The hardness is analyzed on its relation with the mean grain size, as well as with the grain size distribution and the dislocation density. With the help of the variable selection tool LASSO, it is shown that dislocation density, mean grain size and kurtosis of grain size distribution are the three features which most strongly affect hardness of IF steel.     

The influence of the blocking plate diameter on the gas flux distribution in the calibration chamber

This paper is concerned with the influence of the diameter of the blocking plate on the gas flux density distribution in a typical calibration chamber. It was found that, at small values of the blocking plate diameter, the shape of the gas flux density function is similar to the sinus function, with zero deviation from the mean value of the gas flux density at mid-height of the chamber. As the blocking plate diameter increases a discontinuity appears at the edge of the “shadow zone”. Until the discontinuity occurs on the side wall, the difference between the maximum and minimum relative gas flux densities is about 3×10⁻⁴, then it grows to 3.7×10⁻³ when the relative blocking plate diameter increases to 0.83 of the chamber diameter. If we confine our attention to the region between 0.33 and 0.67 of the whole chamber height, which is reasonable in practical terms, the maximum difference decreases to 6×10⁻⁴. Even in this case, this difference is twice as great as that in the case of the chamber without or with the smallest reasonable blocking plate.     

The influence of damage distribution on serious brain injury in occupants in frontal motor vehicle crashes

In spite of improvements in motor vehicle safety systems and crashworthiness, motor vehicle crashes remain one of the leading causes of brain injury. The purpose of this study was to determine if the damage distribution across the frontal plane affected brain injury severity of occupants in frontal impacts. Occupants in "head on" frontal impacts with a Principal Direction of Force (PDOF) equal to 11, 12, or 1o'clock who sustained serious brain injury were identified using the Crash Injury Research Engineering Network (CIREN) database. Impacts were further classified based on the damage distribution across the frontal plane as distributed, offset, and extreme offset (corner). Overall, there was no significant difference for brain injury severity (based on Glasgow Coma Scale<9, or brain injury AIS>2) comparing occupants in the different impact categories. For occupants in distributed frontal impacts, safety belt use was protective (odds ratio (OR)=0.61) and intrusion at the occupant's seat position was four times more likely to result in severe (Glasgow Coma Scale (GCS)<9) brain injury (OR=4.35). For occupants in offset frontal impacts, again safety belt use was protective against severe brain injury (OR=0.25). Possibly due to the small number of brain-injured occupants in corner impacts, safety belts did not significantly protect against increased brain injury severity during corner impacts. This study supports the importance of safety belt use to decrease brain injury severity for occupants in distributed and offset frontal crashes. It also illustrates how studying "real world" crashes may provide useful information on occupant injuries under impact circumstances not currently covered by crash testing.