Journal articles: 'Void coefficient'

1

Hayashi, Takahiro, Takayuki Kobayashi, and Jun Takahashi. "Quantification of the void content of composite materials using soft X-ray transmittance." Journal of Thermoplastic Composite Materials 30, no. 11 (April 24, 2016): 1522–40. http://dx.doi.org/10.1177/0892705716644670.

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Carbon fiber reinforced thermoplastics (CFRTPs) have high potential in high-cycle (1 min) molding as a weight-reducing material for the mass production of automobile components. However, residual voids in CFRTPs lead to diminished and unstable mechanical properties; therefore, the effective quantification of the void content in CFRTP products is necessary for developing an affordable system for mass production. In a previous study, we demonstrated that the X-ray attenuation coefficient decreases with increasing void content; thus, measurements of X-ray attenuation coefficients can be used to estimate the void contents of CFRTPs. In this study, we first investigated in detail the soft X-ray attenuation coefficients of completely impregnated composite materials with three different thicknesses; we observed that the attenuation coefficients decreased with increasing composite thickness, even though they should be independent of the thickness according to the Beer–Lambert law. We next demonstrated that although no correlation exists between the X-ray transmittance and the apparent attenuation coefficient of six composites with various void contents, the true attenuation coefficient modified to account for void content exhibits a good linear relationship with the X-ray transmittance, same as fully impregnated composites. Using the approximation line between the X-ray transmittance and the modified attenuation coefficient of CFRTP, we estimated the void content on the basis of the difference between the apparent and true X-ray attenuation coefficients. The average difference in void content determined by conventional hydrostatic weighing and that determined by the proposed X-ray transmittance method was 0.43%. We therefore concluded that the void content of CFRTPs of any thickness can be estimated nondestructively using soft X-rays.

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Zhang, Yu, Tielin Chen, Yujun Zhang, and Weizhong Ren. "Calculation Methods of Seepage Coefficient for Clay Based on the Permeation Mechanism." Advances in Civil Engineering 2019 (March 3, 2019): 1–9. http://dx.doi.org/10.1155/2019/6034526.

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The existing empirical methods of the seepage coefficient for clay have difficulty in parameter acquisition and are poor in calculation accuracy, and it is possible to find reasonable ones based on the mature empirical methods of coarse-grained soil. Firstly, the permeation mechanism of clay was analysed including influencing factors, spatial process, and parameter calculation, and the ineffective and effective voids were defined; then the empirical methods of clay and coarse-grained soil were summarised and listed. Secondly, clay was put equivalent to coarse-grained soil according to bound-water consolidation, and the parameter “equivalent void ratio” was introduced to establish the equivalent calculation methods. Finally, the liquid-plastic limit method determining the volume of ineffective voids was explained, and the feasibility of equivalent calculation methods was evaluated by three examples. The results show that seepage, permeation, and effective permeation are three different concepts; groundwater permeates in clay via the effective void. For certain soil, the increasing sequence of permeability coefficients is the seepage coefficient, permeation coefficient, and effective permeation coefficient. Introduction of the “equivalent void ratio” unifies the calculation of the seepage coefficient for clay and coarse-grained soil. The maximum of the bound-water content is about 0.9 time the size of liquid limit. The Mesri equation and the equivalent calculation method of Terzaghi or Curson–Karman are suitable for calculating the seepage coefficient of clay for the closest results to experimental values.

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Mikheev, Alexander, Andrei Nazarov, Irina Ershova, and Alexander Zaluzhnyi. "Kinetics of Void Growth in Cubic Metals: Theory and Simulation." Defect and Diffusion Forum 363 (May 2015): 91–98. http://dx.doi.org/10.4028/www.scientific.net/ddf.363.91.

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We examine the effect of elastic stresses induced by growing voids on the diffusion vacancy fluxes using newly derived equations. One of the main goals of our work is to obtain a kinetic equation for the growth rate of voids in cubic metals. The diffusion equation for vacancies, in which the influence of elastic stress near the void on the flux is taken into account, is linearized and solved. Then after mathematical transformations that are similar to Lifshitz - Slyozov theory, kinetic equations for the growth rate of the voids in fcc and bcc metals are obtained. The kinetic equations contain additional terms due to developed strain. This feature distinguishes the present equation from known ones and changes the kinetic of void growth. The functional dependence on strain is determined by coefficients, which characterize the strain influence on diffusion (SID coefficients). These coefficients are very sensitive to the atomic structure in the nearest vicinity of the saddle-point configuration. We have built an advanced model to evaluate them. SID coefficient simulation is the next step of this work. Using the kinetic equations and the SID coefficients, we calculate the void growth rate in cubic metals under different conditions.

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4

Lin, Li, Xiang Zhang, Jun Chen, and Xi Meng Li. "Numerical Investigations of Ultrasonic Scattering from Voids in Composite Materials Based on Random Void Model." Advanced Materials Research 346 (September 2011): 639–43. http://dx.doi.org/10.4028/www.scientific.net/amr.346.639.

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Ultrasonic attenuation coefficient is firstly calculated utilizing the finite difference time domain method based on a novel 2-D RVM for carbon fiber reinforced plastic (CFRP) composite materials. The results show that the void morphology has detrimental effect on ultrasonic attenuation. Even at the fixed porosity, ultrasonic attenuation coefficient fluctuates due to the randomness of void morphology in CFRP composite materials. This work significantly helps to understand ultrasonic scattering mechanism of voids and formulation of CFRP composite material properties.

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Sun, Li Mei, Xia Liu, and Zhan Rong Zhang. "Correlation Analysis of Physical and Mechanical Soil Parameters in Coastal Plain Region." Applied Mechanics and Materials 438-439 (October 2013): 1181–84. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.1181.

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According to the tested physical and mechanical soil parameters of the Coastal Railway in West Guangdong along the broad coastal plain region, the correlation relations between compression modulus, compression coefficient and void ratio, moisture content, density, standard penetration number are analyzed by the linear regression method. The results show that the compression modulus increases with the increase of water content and void ratio, with correlation coefficients being 0.6985 and 0.8147, respectively; the compression modulus decreases with the increase of density and standard penetration number, with correlation coefficients being 0.7827 and 0.4934, respectively; the compression coefficient decreases with the increase of water content and void ratio, with correlation coefficients being 0.9131 and 0.9412, respectively; the compression coefficient decreases with the increase of density and standard penetration number, with correlation coefficients being 0.8187 and 0.4985, respectively. The parameters which are hardly obtained from the test directly can be easily evaluated by using these formulas.

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6

Jones, M. K., M. F. Horstemeyer, and A. D. Belvin. "A Multiscale Analysis of Void Coalescence in Nickel." Journal of Engineering Materials and Technology 129, no. 1 (June 9, 2006): 94–104. http://dx.doi.org/10.1115/1.2400265.

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An internal state variable void coalescence equation developed by Horstemeyer, Lathrop, Gokhale, and Dighe (2000, Theor. Appl. Fract. Mech., 33(1), pp. 31–47) that comprises void impingement and void sheet mechanisms is updated based on three-dimensional micromechanical simulations and novel experiments. This macroscale coalescence equation, developed originally from two-dimensional finite element simulations, was formulated to enhance void growth. In this study, three-dimensional micromechanical finite element simulations were employed using cylindrical and spherical void geometries in nickel that were validated by experiments. The number of voids, void orientation, and void spacing were all varied and tested and simulated under uniaxial loading conditions. The micromechanical results showed excellent agreement with experiments in terms of void volume fractions versus strain and local void geometry images. Perhaps more importantly, the macroscale internal state variable void coalescence equation did not require a functional form change but just a coefficient value modification.

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7

Gan, Deqing, Xi Yang, and Yunpeng Zhang. "Experimental Analysis on Permeability Characteristics of Iron Tailings." Mathematical Problems in Engineering 2019 (March 28, 2019): 1–11. http://dx.doi.org/10.1155/2019/6539846.

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The permeability characteristics of iron tailings are one of the important factors affecting the stability of the tailings dam. The permeability properties of undisturbed iron tailings and disturbed iron tailings were analyzed from various aspects such as FC value, gradation, particle size, specific surface area, and interparticle void ratio with water head test in laboratory. The results show that the permeability coefficients of undisturbed iron tailings and disturbed iron tailings are affected by the fine particles content (FC). The threshold of fine content is about 40%. The traditional formulas for calculating the permeability coefficient are applied. But the results are inaccurate. The relationship between permeability coefficient of the iron tailings (undisturbed iron tailings and disturbed iron tailings) and the nonuniform coefficient (Cu), the curvature coefficient (Cc), the average particle size, the weighted average particle size, the specific surface area, and the skeleton void ratio (es) is nonlinear. It is difficult to characterize the change of permeability coefficient when the fine content is large. However, the relationship between permeability coefficient of the iron tailings (undisturbed iron tailings and disturbed iron tailings) and the effective particle size and silt particles void ratio (ef) is linear. A formula was developed for the determination of permeability coefficient of iron tailings by analyzing the effective particle size and silt particles void ratio. And it is more accurate. The permeability coefficients of disturbed samples are slightly larger than the permeability coefficients of undisturbed sample. This is due to the destruction of the sedimentary structure of the tailings and increasing e. Maybe the R in the new formula is affected by the structure of iron tailings. This requires further research.

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Slavickas, Andrius, Raimondas Pabarčius, Aurimas Tonkūnas, Gediminas Stankūnas, and Eugenijus Ušpuras. "Void Reactivity Coefficient Analysis during Void Fraction Changes in Innovative BWR Assemblies." Science and Technology of Nuclear Installations 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/757201.

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The study of the void reactivity variation in innovative BWR fuel assemblies is presented in this paper. The innovative assemblies are loaded with high enrichment fresh UO2and MOX fuels. UO2fuel enrichment is increased above existing design limitations for LWR fuels (>5%). MOX fuel enrichment with fissile Pu content is established to achieve the same burnup level as that of high enrichment UO2fuel. For the numerical analysis, the TRITON functional module of SCALE 6.1 code with the 238-group ENDF/B-VI cross section data library was applied. The investigation of the void reactivity feedback is performed in the entire 0–100% void fraction range. Higher values of void reactivity coefficient for assembly loaded with MOX fuel are found in comparison with values for assembly loaded with UO2fuel. Moreover, coefficient values for MOX fuel are positive over 75% void fraction. The variation of the void reactivity coefficient is explained by the results of the decomposition analysis based on four-factor formula and neutron absorption reactions for main isotopes. Additionally, the impact of the moderation enhancement on the void reactivity coefficient was investigated for the innovative assembly with MOX fuel.

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9

Li, Wen Bo. "Study on the Permeability Characteristics of Coarse-Grained Soil and its Permeability Rule." Advanced Materials Research 904 (March 2014): 383–88. http://dx.doi.org/10.4028/www.scientific.net/amr.904.383.

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The permeability of coarse-grained soil is influenced by many factors. The results of permeability tests in different conditions indicate the effects of coarse-grained soil dry density of , fines content P5,void ratio e and nonuniform coefficient Cu to the permeability coefficient. Analyzing the relationship between coarse-grained soil dry density , fines content P5, void ratio e, nonuniform coefficient Cu and permeability coefficient, thus there is a relational expression between coarse-grained soil dry density of soil , fines content P5, void ratio e, nonuniform coefficient Cu and permeability coefficient.

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10

Kim, Nam Ho, and Ho Sung Kim. "Statistical Characteristics of Inter-Particle/Void Distance for Particulate Composites." Key Engineering Materials 312 (June 2006): 105–10. http://dx.doi.org/10.4028/www.scientific.net/kem.312.105.

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Two dimensional statistical characteristics of inter particle/void distance (ID) for various particle/void and dispersion types are studied in relation with toughening of plastics using computer generated three dimensional models. Particle/void size groups adopted were of log-normal distribution. Particles/voids were dispersed at uniform-random. It was found that IDs are (a) of approximately Gaussian distribution but; (b) not of Gaussian distribution for particle/void sizes of bimodal log-normal distribution (created by mixing of two groups of articles/voids). It was also found that the degree of ID uniformity, which can be represented by the inverse of the coefficient of variation, for a single group of log-normally sized particles/voids is not sensitive to standard deviation of particle/void size. Mixing effect on ID characteristics using two groups of log-normally distributed particles/voids with similar mean particle/void diameters was simulated. It was found that, when a significant amount (36 vol %) of particles/voids of a small mean and standard deviation of ID, was mixed with a group of particles/voids of a large mean and standard deviation of ID, mean and standard deviation of ID for the mixture were not substantially lower than those of the group of particles/voids of the large mean and standard deviation of ID. It was also found that the degree of ID uniformity for the mixture of the two groups were lower than those of individual groups, indicating that the mixing has deleterious effect on toughening.

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11

Williams, M. M. R. "Calculation of the Void Fraction and Void Coefficient in an Aqueous Homogeneous Reactor." Nuclear Science and Engineering 168, no. 2 (June 2011): 138–50. http://dx.doi.org/10.13182/nse11-45.

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Slavickas, Andrius, Raimondas Pabarčius, Aurimas Tonkūnas, and Gediminas Stankūnas. "Decomposition Analysis of Void Reactivity Coefficient for Innovative and Modified BWR Assemblies." Science and Technology of Nuclear Installations 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/132737.

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The decomposition analysis of void reactivity coefficient for innovative BWR assemblies is presented in this paper. The innovative assemblies were loaded with high enrichment UO2and MOX fuels. Additionally the impact of the moderation enhancement on the void reactivity coefficient through a full fuel burnup discharge interval was investigated for the innovative assembly with MOX fuel. For the numerical analysis the TRITON functional module of SCALE code with ENDF/B-VI cross section library was applied. The obtained results indicate the influence of the most important isotopes to the void reactivity behaviour over a fuel burnup interval of 70 GWd/t for both UO2and MOX fuels. From the neutronic safety concern positive void reactivity coefficient values are observed for MOX fuel at the beginning of the fuel irradiation cycle. For extra-moderated assembly designs, implementing 8 and 12 water holes, the neutron spectrum softening is achieved and consequently the lower void reactivity values. Variations in void reactivity coefficient values are explained by fulfilled decomposition analysis based on neutrons absorption reactions for separate isotopes.

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13

Ma, Wen, and Fushun Liu. "EFFECTS OF POROSITY ON ULTRASONIC CHARACTERISTIC PARAMETERS AND MECHANICAL PROPERTIES OF GLASS FIBER REINFORCED COMPOSITES." International Journal of Modern Physics: Conference Series 06 (January 2012): 646–51. http://dx.doi.org/10.1142/s2010194512003911.

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Voids are inevitable in the fabrication of fiber reinforced composites and have a detrimental impact on mechanical properties of composites. Different void contents were acquired by applying different vacuum bag pressures. Ultrasonic inspection and ablation density method were adopted to measure the ultrasonic characteristic parameters and average porosity, the characterization of voids' distribution, shape and size were carried out through metallographic analysis. Effects of void content on the tensile, flexural and interlaminar shear properties and the ultrasonic characteristic parameters were discussed. The results showed that, as vacuum bag pressure went from -50kPa to -98kPa, the voids content decreased from 4.36 to 0.34, the ultrasonic attenuation coefficient decreased, but the mechanical strengths all increased.

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14

Ueda, Mitsutoshi, Kenichi Kawamura, and Toshio Maruyama. "Void Formation in Magnetite Scale Formed on Iron at 823 K -Elucidation by Chemical Potential Distribution-." Materials Science Forum 522-523 (August 2006): 37–44. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.37.

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Estimation of void formation in oxide scale is important for predicting exfoliation of the oxide scale. Void formation in magnetite scale formed on iron at 823 K has been elucidated by chemical potential distribution, flux of oxide ion and its divergence. This calculation also estimates a effective diffusion coefficient, which includes both lattice diffusion and grain boundary diffusion in magnetite scale. The resulting effective diffusion coefficients give the quantitative elucidation of the morphology of the magnetite scale. The divergence of oxide ion explains well a position and an amount of void in magnetite scale.

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15

Williams, M. M. R. "Corrigendum: Calculation of the Void Fraction and Void Coefficient in an Aqueous Homogeneous Reactor." Nuclear Science and Engineering 169, no. 3 (November 2011): 340. http://dx.doi.org/10.13182/nse11-a12643.

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16

Zhang, Bei, Xiaoliang Wang, Yanhui Zhong, Xiaolong Li, Meimei Hao, Yuanhao Ding, Jianyang Liu, and Xu Zhang. "Temperature Correction for FWD Deflection in Cement Pavement Void Detection." Advances in Civil Engineering 2021 (February 10, 2021): 1–14. http://dx.doi.org/10.1155/2021/6668003.

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The use of the falling weight deflectometer (FWD) for detecting pavement voids is based on the principle that, under the same impact load, the deflection of pavements with voids increases significantly. Under the effect of temperature, the cement pavement becomes warped, which affects the deflection detection accuracy. In order to improve the accuracy of FWD detection of cement pavement voids, a three-dimensional numerical model of cement pavement on a multilayered elastic foundation under the coupled action of temperature and load is established in this paper. In addition, under different pavement void, climatic, and load conditions, the influence of temperature difference between top and bottom of the plate on the deflection of the center point of plate angle load is studied. Considering the temperature difference between top and bottom, the temperature correction coefficient is established and experimentally verified the accuracy of the temperature correction coefficient. The results showed that, within the ranges of positive and negative temperature differences, the fitting degree of the temperature correction coefficient for the cement pavement exceeded 0.99, which was consistent with the variation trend of the temperature correction coefficient obtained through field tests. The error was lower than 7%, which verified the applicability of the temperature correction coefficient for the dynamic deflection of cement pavements based on FWD. The accuracy of the FWD method in detecting cement pavement voids was improved, and this study demonstrated theoretical reference value and practical engineering significance.

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Lestani, H., P. Florido, and J. González. "Conceptual Engineering of CARA Fuel Element with Negative Void Coefficient for Atucha II." Science and Technology of Nuclear Installations 2011 (2011): 1–9. http://dx.doi.org/10.1155/2011/264235.

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Experimentally validated void reactivity calculations were used to study the feasibility of a change in the design basis of Atucha II Nuclear Power Plant including the Large LOCA event. The use of CARA fuel element with burnable neutronic absorbers and enriched uranium is proposed instead of the original fuel. The void reactivity, refuelling costs, and power peaking factors are analysed at conceptual level to optimize the burnable neutronic absorber, the enrichment grade, and their distribution inside the fuel. This work concludes that, for the considered plant conditions, either a void reactivity coefficient granting no prompt critical excursion on Large LOCA or negative void reactivity is achievable, with advantages on refuelling cost and linear power density.

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Zhang, Zhen Ying, Da Zhi Wu, and Qi Mao Cai. "Experimental Study on the Permeability of Fresh Municipal Solid Waste." Advanced Materials Research 599 (November 2012): 547–50. http://dx.doi.org/10.4028/www.scientific.net/amr.599.547.

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Basing on traditional constant head permeability test with large scale specimen, the permeability of municipal solid waste has been studied. The municipal solid waste material is divided into three parts: the material that is easy to be biodegraded, reinforced material that is difficult to be biodegraded and the incompressible solid waste material. Two different proportions of these three parts, which are 50%, 15%, 35% and 65%, 10%, 25% are selected. A series of laboratory tests have been performed for different initial void ratios, and the initial void ratios are 2.5, 3.0 and 3.5, respectively. Testing results show that the initial void ratio and the content of the organic matter are the main influence factors on the permeability coefficient of the municipal solid waste. Besides, the coefficient of permeability decreases with the decreasement of the initial void ratio of the municipal solid waste. Furthermore, when the proportion of the three parts is 65%, 10% and 25%, the coefficient of permeability varies from 7.8×10-4 to 3.72×10-3 centimeter per second, and when the proportion of three parts is 50%, 15% and 35%, the coefficient of permeability varies from 1.08×10-3 to 6.67×10-3 centimeter per second.

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Xu, Bin Bin, Ai Hua Liang, and Ming Ying Li. "Effect of Variable Permeability Coefficient on Consolidation of Ultra-Soft Ground under Vacuum Preloading." Applied Mechanics and Materials 580-583 (July 2014): 56–60. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.56.

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In this paper, a soil-water coupled finite element analysis incorporated the macro-element method is carried out to investigate the effect of variable permeability coefficient on the consolidation of the ultra-soft ground using vacuum preloading. Sys cam-clay model is employed as the constitutive model of the ultra-soft soils. When the drain space becomes from 60cm to 40cm, there is significant acceleration in the numerical settlement of the ground using the constant permeability coefficient, which is quite different from the observational results. When the variable permeability coefficient where a liner relationship between the void and the logarithmic value of permeability coefficient is adopted is employed, there is a good accordance between the numerical and observational settlements. According to the distribution of variation in the void, the largest variation in the void occurs at the top several layers and therefore the predominant settlement can be attributed to the volumetric compression of the top several layers.

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Davies, Una, Marat Margulis, Eugene Shwageraus, Emil Fridman, Nuria Garcia-Herranz, Jimenez-Carrascosa Antonio, Cabellos Oscar, Gregg Robbie, and Krepel Jiri. "EVALUATION OF THE ESFR END OF CYCLE STATE AND DETAILED ANALYSIS OF SPATIAL DISTRIBUTIONS OF REACTIVITY COEFFICIENTS." EPJ Web of Conferences 247 (2021): 02001. http://dx.doi.org/10.1051/epjconf/202124702001.

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The ESFR-SMART project is the latest iteration of research into the behaviour of a commercial-size SFR core throughout its lifetime. As part of this project the ESFR core has been modelled by a range of different reactor physics simulation codes at its end of cycle state, and the important safety relevant parameters evaluated. These parameters are found to agree well between the different codes, giving good confidence in the results. A detailed mapping of the local sodium void worth is also performed due to the problems associated with the positive void coefficient seen in large SFR designs. The local void worth maps show that the use of zone-wise coefficients replicates the important reactivity feedbacks to a high degree, indicating their suitability for use in SFR simulations.

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Wan, Yong Ping, and Liang Liang Fan. "Modeling the Piezoelectric D₃₃ Coefficient of Voided Charged Polypropylene Film by Finite Element Method." Advanced Materials Research 347-353 (October 2011): 3375–78. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3375.

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Voided charged Polypropylene films have very large piezoelectric d33 coefficient and have emerged as a kind of novel electromechanical transducer materials. In this paper, we propose the analysis method of piezoelectric d33 coefficient of voided charged Polypropylene film by finite element model. The very flat voids are simulated by the hollow oblate tetrakaidecahedron and periodic boundary conditions are implied. The electrostatic analysis is conducted and elastic deformation is solved by using ANSYS FE software. Qualitative analysis is presented for the piezoelectric d33 coefficient, and several influencing parameters are discussed, including void geometry and charge density. This finite element model can provide help in the analysis and design of voided charged polymer film with complex microstructures.

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Slavickas, Andrius, Raimondas Pabarčius, Aurimas Tonkūnas, and Eugenijus Ušpuras. "Analysis of Void Reactivity Coefficient for 3D BWR Assembly Model." Science and Technology of Nuclear Installations 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/3427549.

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The effect of BWR fuel assembly 3D model on void reactivity coefficient (VRC) estimation is investigated. VRC values were calculated for different BWR assembly models applying deterministic T-NEWT and Monte Carlo KENO-VI functional modules of SCALE 6.1 code package. The difference between deterministic T-NEWT and Monte Carlo KENO-VI simulations is negligible (0.18 pcm/%). The influence of the assumed more detailed coolant density profile was estimated as well. VRC increases with the application of a larger number of coolant density values across fuel assembly height. It was shown that the coolant density profile described by 6 values per height could be considered sufficient from prospect of VRC estimation, as a more detailed density profile has impact below 1% on total assembly void effects. VRC values were decomposed to values for individual nodes and isotopes, since decomposition provides useful insights to describe the overall behaviour of VRC in detail.

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Chi, Lu Lu, Jian Min Qin, and Xue Feng Chen. "DEM Simulation of Micro-Macro Mechanical Behaviour of Granular Materials." Advanced Materials Research 663 (February 2013): 441–46. http://dx.doi.org/10.4028/www.scientific.net/amr.663.441.

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The mechanical responses of granular materials are affected significantly by the properties of the individual particle. In order to establish the link between the micro and macro parameters, series of numerical biaxial simulations are carried out using two-dimensional discrete element method. The microscale mechanisms of mechanical behavior of granular materials are investigated through sensitivity analyses. The key influence of microscale parameters on the strength and deformation are discussed respectively. The peak strength depends on void ratio, friction coefficient and confining stress significantly. The elastic modulus is affected by friction coefficient, confining pressure and stiffness ratio, especially when the friction coefficient ranges from 0.1 to 0.3. The samples with different initial void ratio under the same loading condition can finally achieve the same critical state; the critical states at micro and macro scale are both independent of the initial void ratio.

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Gopalakrishna, Suhas Badakere, Ravi Lakkanna, and Satyabhama Alangar. "Investigation of Forced Convective and Subcooled Flow Boiling Heat Transfer Coefficients of Water-Ethanol Mixture: Numerical Study." International Journal of Heat and Technology 39, no. 2 (April 30, 2021): 512–20. http://dx.doi.org/10.18280/ijht.390221.

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The subcooled flow boiling is related to the operation of electronic devices, Hybrid electric vehicle (HEV) Battery module and small catalytic reactors. It is well known that the operational temperature must be maintained to avoid any malfunction of these heat dissipative devices. In this paper the forced convective and subcooled flow boiling heat transfer coefficients of water-ethanol mixture is determined numerically by Volume of fluid analysis (VOF). The interaction between liquid and local vapour is analysed by solving the bubble volume of fraction in the numerical study. Crank Nicolson implicit scheme is used for discretizing the scalar convection equation for bubble void fraction and transforming into algebraic equation. Thomas Algorithm is used to solve the algebraic equations of bubble void fraction. The corrector predictor equation method is used to solve for bubble void fraction when the value obtained is less than 0 or exceeds 1. The thermodynamic and Thermophysical properties are substituted in the x-momentum and energy equation to determine the values of pressure drop, velocity and temperature of the fluid. From the temperature values, the subcooled flow boiling heat transfer coefficient is obtained. It is found that the addition of ethanol to water decreases the forced convective and subcooled flow boiling heat transfer coefficient of the water-ethanol mixture. The numerically determined heat transfer coefficient of water ethanol mixture is compared with that of the experimental results. The average deviation between the experimentally determined and numerically determined subcooled flow boiling heat transfer coefficient of water ethanol-mixture is found to be 24.13%.

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Shen, Chaojie, Zhaoyang Xu, Jie Yin, and Jinfeng Wu. "Prediction Model of Minimum Void Ratio for Various Sizes/Shapes of Sandy Binary Mixture." Advances in Civil Engineering 2020 (June 30, 2020): 1–19. http://dx.doi.org/10.1155/2020/1898953.

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The minimum void ratio is a fundamental physical index for evaluating particle properties in soil mechanics, ceramic processing, and concrete mixes. Previous research found that both particle size distribution and particle shape characteristics would affect minimum void ratio, while the current research generally uses a linear model to estimate the minimum void ratio of a binary mixture, ignoring quantitative effect of particle shape on the minimum void ratio. Based on a study of binary mixtures of natural sand from three different origins and iron particles of two different shapes, this paper analyzes the influence factors of the minimum void ratio, and a quadratic nonlinear model is proposed for estimating the minimum void ratio of binary mixture. The model contains only one undetermined coefficient, a, the value of which is correlated to the particle sphericity, particle size, and particle size ratio. A theoretical calculation formula for the coefficient a is proposed to quantitatively analyze the effects of these three factors on the size of the parameters. In the end, the model is used to estimate the minimum void ratios of sand and substitute particles from different producing areas; the average difference between the estimated values and the fitted values is about 2.03%, suggesting that the estimated values of the model fit well with the measured data.

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Kawahara, A., M. Sadatomi, K. Kano, Y. Sasaki, and H. Kudo. "VOID DIFFUSION COEFFICIENT IN TWO-PHASE VOID DRIFT FOR SEVERAL CHANNELS OF TWO- AND MULTI-SUBCHANNEL SYSTEMS." Multiphase Science and Technology 18, no. 1 (2006): 31–54. http://dx.doi.org/10.1615/multscientechn.v18.i1.20.

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Liu, Jian Long, Jie Nan Xie, Peng Liu, and Mu Ye Huang. "Research on the Pass Optimization Design of Sintered Shale Porous Brick." Applied Mechanics and Materials 672-674 (October 2014): 1879–84. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.1879.

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The equivalent thermal conductivity coefficient of 10 kinds of sintered shale porous brick with different void number, void ratio, and arrangement (size: 240mm x 190mm x 90mm) are studied through 3D numerical simulation. An optimal structure design of the shale perforated brick design has been obtained. At the same time, factors such as void ratio, void number and arrangement of porous brick affected thermal insulation performance are systematically analyzed, which provides a reference to further improving the thermal insulation performance of insulation sintered shale porous brick model.

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Kim, Kyeong-Su, Man-Il Kim, Moon-Se Lee, and Eui-Soon Hwang. "Regression Equations for Estimating Landslide-Triggering Factors Using Soil Characteristics." Applied Sciences 10, no. 10 (May 21, 2020): 3560. http://dx.doi.org/10.3390/app10103560.

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Landslides, which often occur on natural slopes of mountainous areas and artificial slopes around urban areas during summer in South Korea, are mostly caused by localized heavy rainfalls and typhoons. A survey was conducted, and the characteristics of landslide occurrences in different geological conditions—in this case, granite soils in Sangju area and gneiss soils in Yangu area—were analyzed. Soil characteristics in the landslide and non-landslide areas and the surroundings of each geological condition were also evaluated. Triggering factors, namely permeability coefficients (k), shear strength with cohesion (c), and internal friction angle (φ) of soils that are closely linked to landslides around weathered soil layers were extracted based on the examined characteristics and a statistics method. The study used regression analysis to formulate equations to estimate the permeability coefficients and shear strength. Ultimately, the permeability coefficients showed significant results in terms of void ratio (e), the effective size of grains (D10), and uniformity coefficient (cu), while shear strength correlated with the proportion of fine-grained soil (Fines), uniformity coefficient (cu), degree of saturation (S), dry weight density (rd), and void ratio (e).

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Li, Linjie, Shuaidong Yang, and Tong Su. "Numerical Analysis of the Preloading Consolidation of the Soft Foundation with a Plastic Drainage Plate." Advances in Civil Engineering 2021 (August 4, 2021): 1–10. http://dx.doi.org/10.1155/2021/6123860.

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The permeability coefficient and void ratio are related to the stress state of the soil, which manifests as the temporal and spatial variability of consolidation. Based on the modified Cambridge model, this paper quotes the functional relationship between the soil permeability coefficient and void ratio and soil stress obtained by Tylor’s research and then uses finite-element software ABAQUS and its secondary development platform to establish a plastic drainage plate surcharge preloading numerical model that considers the influence of the void ratio and permeability coefficient with stress changes. The results show that considering the variability of the permeability coefficient in the consolidation process of the soft foundation has a great influence on the change of the consolidation state but has a small effect on the final consolidation state. For soft foundation surcharge preloading reinforcement treatment, if the strength of the soft foundation is low but the surcharge is large, the geometric nonlinearity and material nonlinearity should be considered. Using the theory of large deformation consolidation to calculate the consolidation of soil is closer to the actual situation.

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Portinari, D., A. Cammi, S. Lorenzi, M. Aufiero, Y. Calzavara, and A. Bidaud. "VOID COEFFICIENT SENSITIVITY ANALYSIS FOR THE TRIGA MARK II REACTOR AT L.E.N.A. (UNIPV)." EPJ Web of Conferences 247 (2021): 15005. http://dx.doi.org/10.1051/epjconf/202124715005.

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Sensitivity analysis studies the effect of a change in a given parameter to a response function of the system under investigation. In reactor physics, this usually translates into the study of how cross sections and fission spectrum modifications affect the value of the multiplication factor, the delayed neutron fraction or the void coefficient for example. Generalized Perturbation Theory provides a useful tool for the assessment of adjoint weighed functions such as keff and void coefficient sensitivities. In this work, the capability of SERPENT code to perform sensitivity calculation based on GPT is used to study the TRIGA Mark II research reactor installed at L.E.N.A. of University of Pavia. A general sensitivity analysis to the most important reactor’s cross sections has been performed in order to highlight the biggest reactivity contributions. Two numerically challenging tasks related to GPT calculation have been performed thanks to the relatively quick Monte Carlo approach allowed by this reactor: investigating the linearity of the reactivity injection caused by the flooding of the central channel, and calculating the fuel void coefficient sensitivity to the coolant density.

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Kaur, Gurwinderpal, Dilbag Singh, and SK Tomar. "Love waves in a nonlocal elastic media with voids." Journal of Vibration and Control 25, no. 8 (January 25, 2019): 1470–83. http://dx.doi.org/10.1177/1077546318824144.

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The propagation of Love-type waves in a nonlocal elastic layer with voids resting over a nonlocal elastic solid half-space with voids has been studied. Dispersion relations are derived using appropriate boundary conditions of the model. It is found that there exist two fronts of Love-type surface waves that may travel with distinct speeds. The appearance of the second front is purely due to the presence of voids in layered media. Both fronts are found to be dispersive in nature and affected by the presence of the nonlocality parameter. The first front is found to be nonattenuating, independent of void parameters and analogous to the Love wave of classical elasticity, while the second front is attenuating and depends on the presence of void parameters. Each of the fronts is found to face a critical frequency above which it ceases to propagate. For a specific model, the variation of the phase speeds of both the fronts with frequency, nonlocality, voids and thickness parameters is shown graphically. Attenuation coefficient versus frequency for the second front has also been depicted separately. Some particular cases are deduced from the present formulation.

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Dwijayanto, R. Andika Putra, and Dedy Prasetyo Hermawan. "INVESTIGATION ON INHERENT SAFETY OF ONE FLUID-MOLTEN SALT REACTOR (OF-MSR) WITH VARIOUS STARTING FUEL." JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA 22, no. 2 (May 30, 2020): 54. http://dx.doi.org/10.17146/tdm.2020.22.2.5893.

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Molten salt reactor (MSR) is often associated with thorium fuel cycle, thanks to its excellent neutron economy and online reprocessing capability. However, since 233U, the fissile used in pure thorium fuel cycle, is not commercially available, the MSR must be started with other fissile nuclides. Different fissile yields different inherent safety characteristics, and thus must be assessed accordingly. This paper investigates the inherent safety aspects of one fluid MSR (OF-MSR) using various fissile fuel, namely low-enriched uranium (LEU), reactor grade plutonium (RGPu), and reactor grade plutonium + minor actinides (PuMA). The calculation was performed using MCNPX2.6.0 programme with ENDF/B-VII library. Parameters assessed are temperature coefficient of reactivity (TCR) and void coefficient of reactivity (VCR). The result shows that TCR for LEU, RGPu, and PuMA are -3.13 pcm, -2.02 pcm and -1.79 pcm, respectively. Meanwhile, the VCR is negative only for LEU, whilst RGPu and PuMA suffer from positive void reactivity. Therefore, for the OF-MSR design used in this study, LEU is the only safe option as OF-MSR starting fuel.Keywords: MSR, Temperature coefficient of reactivity, Void coefficient of reactivity, Low enriched uranium, Reactor grade plutonium, Minor actinides

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Taha, Mazahir M. M., Cheng-Pei Feng, and Sara H. S. Ahmed. "Modification of Mechanical Properties of Expansive Soil from North China by Using Rice Husk Ash." Materials 14, no. 11 (May 24, 2021): 2789. http://dx.doi.org/10.3390/ma14112789.

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The construction of buildings on expansive soils poses considerable risk of damage or collapse due to soil shrinkage or swelling made likely by the remarkable degree compressibility and weak shear resistance of such soils. In this research, rice husk ash (RHA) was added to expansive soil samples in different quantities of 0%, 4%, 8%, 12%, and 16% by weight of soil to determine their effects on the plasticity index, compaction parameters, consolidation performance, and California bearing ratio (CBR)of clay soil. The results show that the use of RHA increases the effective stress and decreases the void ratio and coefficient of consolidation. Adding 16% RHA resulted in the greatest reduction in the hydraulic conductivity, void ratio, and coefficient of consolidation. The void ratio decreased from 0.96 to 0.93, consolidation coefficient decreased from 2.52 to 2.33 cm2/s, and hydraulic conductivity decreased from 1.12 to 0.80 cm/s. The addition of RHA improved the soil properties and coefficient of consolidation due to the high density and cohesiveness of RHA. The results of this study can be used to provide a suitable basis for the treatment of expansive soil to provide improved conditions for infrastructure construction.

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Chen, Shengli, and Cenxi Yuan. "Neutronic Analysis on Potential Accident Tolerant Fuel-Cladding Combination U3Si2-FeCrAl." Science and Technology of Nuclear Installations 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/3146985.

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Neutronic performance is investigated for a potential accident tolerant fuel (ATF), which consists of U3Si2fuel and FeCrAl cladding. In comparison with current UO2-Zr system, FeCrAl has a better oxidation resistance but a larger thermal neutron absorption cross section. U3Si2has a higher thermal conductivity and a higher uranium density, which can compensate the reactivity suppressed by FeCrAl. Based on neutronic investigations, a possible U3Si2-FeCrAl fuel-cladding system is taken into consideration. Fundamental properties of the suggested fuel-cladding combination are investigated in a fuel assembly. These properties include moderator and fuel temperature coefficients, control rods worth, radial power distribution (in a fuel rod), and different void reactivity coefficients. The present work proves that the new combination has less reactivity variation during its service lifetime. Although, compared with the current system, it has a little larger deviation on power distribution and a little less negative temperature coefficient and void reactivity coefficient and its control rods worth is less important, variations of these parameters are less important during the service lifetime of fuel. Hence, U3Si2-FeCrAl system is a potential ATF candidate from a neutronic view.

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Babu, G. L. Sivakumar, N. S. Pandian, and T. S. Nagaraj. "A reexamination of the permeability index of clays." Canadian Geotechnical Journal 30, no. 1 (February 1, 1993): 187–91. http://dx.doi.org/10.1139/t93-016.

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The permeability index Ck, similar to the compression index, is the slope of the void ratio – coefficient of permeability relationship. Literature shows that, in general, for sensitive clays it can be related to initial void ratio by Ck = 0.5e0. The possibility of obtaining such a relationship for Cochin marine clays in terms of liquid limit void ratio is indicated in this paper. Analysis of permeability behaviour of Cochin marine clays and the test results available in published literature using generalized state parameter approach show that, in principle, these forms of equations for the permeability index are tenable, even though they were obtained based on experimental observation alone. Key words : permeability index, initial void ratio, void ratio at liquid limit, generalized state parameter approach.

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Sung, Y., R. L. Oelrich, C. C. Lee, N. Ruiz-Esquide, M. Gambetta, and C. M. Mazufri. "Benchmark of Subchannel Code VIPRE-W with PSBT Void and Temperature Test Data." Science and Technology of Nuclear Installations 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/757498.

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This paper summarizes comparisons of VIPRE-W thermal-hydraulic subchannel code predictions with measurements of fluid temperature and void from pressurized water reactor subchannel and bundle tests. Using an existing turbulent mixing model, the empirical coefficient derived from code predictions in comparison to the fluid temperature measurement is similar to those from previous mixing tests of similar bundle configurations. The predicted steady-state axial void distributions and time-dependent void profiles based on the Lellouche and Zolotar model generally agree well with the test data. The void model tends to predict lower void at the upper elevation under bulk boiling. The void predictions are in closer agreement with the measurements from the power increase, temperature increase, and flow reduction transients than the depressurization transient. Additional model sensitivity studies showed no significant improvement in the code predictions as compared to the published test data.

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Ismail, Ahmad Safwan, Mohammad Jawaid, and Jesuarockiam Naveen. "Void Content, Tensile, Vibration and Acoustic Properties of Kenaf/Bamboo Fiber Reinforced Epoxy Hybrid Composites." Materials 12, no. 13 (June 28, 2019): 2094. http://dx.doi.org/10.3390/ma12132094.

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This study aims to investigate the void content, tensile, vibration and acoustic properties of kenaf/bamboo fiber reinforced epoxy hybrid composites. The composites were made using the hand lay-up method. The weight ratios of kenaf/bamboo were 30:70, 50:50 and 70:30. Further, kenaf and bamboo composites were fabricated for the purpose of comparison. The hybridization of woven kenaf/bamboo reduced the void content. The void contents of hybrid composites were almost similar. An enhancement in elongation at break, tensile strength and modulus of hybrid composites was observed until a kenaf/bamboo ratio of 50:50. Kenaf/bamboo (50:50) hybrid composite displays the highest elongation at break, tensile strength and modulus compared to the other hybrid composites which are 2.42 mm, 55.18 MPa and 5.15 GPa, respectively. On the other hand, the highest natural frequency and damping factors were observed for Bamboo/Kenaf (30:70) hybrid composites. The sound absorption coefficient of composites were measured in two conditions: without air gap and with air gap (10, 20, 30 mm). The sound absorption coefficient for testing without air gap was less than 0.5. Introducing an air gap improved the sound absorption coefficient of all composites. Hence, hybrid kenaf/bamboo composites exhibited less void content, as well as improved tensile, vibration and acoustic properties.

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Khirevich, Siarhei, Alexandra Höltzel, and Ulrich Tallarek. "Validation of Pore-Scale Simulations of Hydrodynamic Dispersion in Random Sphere Packings." Communications in Computational Physics 13, no. 3 (March 2013): 801–22. http://dx.doi.org/10.4208/cicp.361011.260112s.

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AbstractWe employ the lattice Boltzmann method and random walk particle tracking to simulate the time evolution of hydrodynamic dispersion in bulk, random, monodisperse, hard-sphere packings with bed porosities (interparticle void volume fractions) between the random-close and the random-loose packing limit. Using Jodrey-Tory and Monte Carlo-based algorithms and a systematic variation of the packing protocols we generate a portfolio of packings, whose microstructures differ in their degree of heterogeneity (DoH). Because the DoH quantifies the heterogeneity of the void space distribution in a packing, the asymptotic longitudinal dispersion coefficient calculated for the packings increases with the packings’ DoH. We investigate the influence of packing length (up to 150 dp, where dp is the sphere diameter) and grid resolution (up to 90 nodes per dp) on the simulated hydrodynamic dispersion coefficient, and demonstrate that the chosen packing dimensions of 10 dpx 10 dpx 70 dp and the employed grid resolution of 60 nodes per dp are sufficient to observe asymptotic behavior of the dispersion coefficient and to minimize finite size effects. Asymptotic values of the dispersion coefficients calculated for the generated packings are compared with simulated as well as experimental data from the literature and yield good to excellent agreement.

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Lin, Li, Xiang Zhang, Jun Chen, Yunfei Mu, and Ximeng Li. "A novel random void model and its application in predicting void content of composites based on ultrasonic attenuation coefficient." Applied Physics A 103, no. 4 (October 19, 2010): 1153–57. http://dx.doi.org/10.1007/s00339-010-6061-x.

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40

Jatuff, F., F. Giust, J. Krouthén, S. Helmersson, and R. Chawla. "Effects of void uncertainties on the void reactivity coefficient and pin power distributions for a 10×10 BWR assembly." Annals of Nuclear Energy 33, no. 2 (January 2006): 119–25. http://dx.doi.org/10.1016/j.anucene.2005.09.007.

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41

Jatuff, F., G. Perret, M. F. Murphy, F. Giust, and R. Chawla. "Void reactivity coefficient benchmark results for a 10×10 BWR assembly in the full 0–100% void fraction range." Annals of Nuclear Energy 36, no. 6 (June 2009): 853–58. http://dx.doi.org/10.1016/j.anucene.2009.02.013.

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42

Wood, Paul, Muhammad Jawad Qarni, and Andrzej Rosochowski. "Effect of Friction and Back Pressure on the Formability of Superplastically Formed Aluminium Alloy Sheet." Key Engineering Materials 473 (March 2011): 532–39. http://dx.doi.org/10.4028/www.scientific.net/kem.473.532.

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This paper examines the effect of friction and back pressure on the formability of superplastically formed aluminium alloy AA7475 sheet at the temperature of 517 °C. Several experiments with lubrication and back pressure are performed using a simple box shape tool cavity. The coefficient of Coulomb friction between the formed sheet and tool has been determined indirectly using a finite element model to simulate superplastic forming of the box shape. Typical values determined for all lubricant conditions tested are in the range 0.1 < μ < 0.2. The void growth with strain was determined directly from measurements as a function of back pressure. The results show the application of back pressure at 1 MPa reduces the growth of voids from 7% to 0.3% void volume fraction at a logarithmic thickness strain of 0.65. This paper reports back pressure has a significantly greater role than friction in enhancing the formability of the alloy.

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43

Raznicyn, Aleksandr V., and Ivan S. Putilov. "Development of a Methodological Approach to Identifying Petrophysical Types of Complicated Carbonate Rocks According to Laboratory Core Studies." Недропользование 21, no. 3 (December 15, 2021): 109–16. http://dx.doi.org/10.15593/2712-8008/2021.3.2.

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Petrophysical typification of productive hydrocarbon deposits is one of the main stages of building a petrophysical model of a reservoir. For carbonate reservoirs characterized by a heterogeneous complex structure of the void space, the problem of identifying petrotypes is very relevant. An extensive literature review of existing methods of petrophysical typification showed that the most well-known and widely used of them were based on simple theoretical models of the structure of the void space of rocks, which did not allow a full description of complex carbonate deposits. Moreover, the petrotypes identified on the basis of these methods did not agree with the results of microdescription of thin sections. A new methodological approach to the identification of petrophysical types of complex carbonate rocks was proposed, based on the integration of the results of standard (determination of the absolute gas permeability and open porosity coefficients) and special (nuclear magnetic resonance studies) core studies and data obtained in the lithological description of thin sections. The developed approach took into account the main petrophysical properties of rocks that characterize its reservoir potential, as well as the structural features of the void space and the influence of secondary transformations. The proposed methodological approach was applied to distinguish petrophysical types in the section of the Assel-Sakmara deposits of the Yareyuskoye field: six petrotypes were identified and described in detail, combined into four zones (zone of development of healed fracturing, zone of development of leaching, zone of development of leaching and open fracturing, zone of development open fracturing), for each of them, individual dependences of the absolute gas permeability coefficient on the open porosity coefficient and the Leverett J-function on the water saturation coefficient were constructed. The information obtained would allow a differentiated approach to geological and hydrodynamic modeling of a hydrocarbon reservoir.

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OGAWA, Kazuhiko, and Fumito KAMINAGA. "New Estimation Method for Void Reactivity Coefficient Using the TRACY Transient Data." Journal of Nuclear Science and Technology 46, no. 1 (January 2009): 1–5. http://dx.doi.org/10.1080/18811248.2007.9711499.

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45

Akimov, I. S. "Void coefficient of ÉGP-6 reactors at the Bilibino nuclear power plant." Atomic Energy 85, no. 1 (July 1998): 431–37. http://dx.doi.org/10.1007/bf02358777.

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46

Zhang, Ming, Jin Fan, and You Ming Zhao. "Laboratory Investigation of Compressibility Characteristics of Dredged Fill in the Qianwan Area Shenzhen." Advanced Materials Research 261-263 (May 2011): 561–65. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.561.

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The existing disadvantage of traditional consolidation test apparatus in determining compressibility characteristics of high water content and high compressibility dredged fill is overcome by GDS consolidation test apparatus, which can accurately measure void ratio after consolidation tests under different consolidation pressures. Laboratory consolidation tests are performed on dredged fill of high water content from 110 percent to 150 percent in the Qianwan area Shenzhen by GDS consolidation test systems, the results are shown as follows: compression strain of dredged fill is 24.73 percent under small and first level consolidation pressure, which is approximately half of cumulative compression strain under whole consolidation pressure; Compression parameters including compression coefficient, bulk compression coefficient and compression modulus has a significant variation with void ratio decreasing under consolidation pressure from 6kPa to 400kPa, the variation of which is from several times to a hundred times, and the nonlinear power function relationship of consolidation pressure -void ratio is shown. GDS consolidation test systems will provide an advanced means for determining compressibility characteristic and compression parameters of dredged fill, and the research achievements in this test will provide a theoretical basis for determining nonlinear relationship of consolidation pressure -void ratio and the parameters for finite-strain consolidation behaviors numerical analysis of dredged fill.

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47

Huang, Shangyan, S. L. Barbour, and D. G. Fredlund. "Development and verification of a coefficient of permeability function for a deformable unsaturated soil." Canadian Geotechnical Journal 35, no. 3 (June 1, 1998): 411–25. http://dx.doi.org/10.1139/t98-010.

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The modelling of flow through saturated/unsaturated soils has become routine in geotechnical and geo-environmental engineering. The analysis requires that the coefficient of permeability for an unsaturated soil be defined. The coefficient of permeability can be estimated based on currently available procedures. However, each procedure has limitations and consequently cares should be taken in the selection of a proper procedure. The coefficient of permeability of a saturated soil is a function of void ratio. The coefficient of permeability of an unsaturated soil of constant volume, is a function of the degree of saturation. However, soil is deformable and both the degree of saturation and the void-ratio influence the coefficient of permeability of a compressible, unsaturated soil. In this paper, the literature pertaining to the coefficient of permeability function for an unsaturated soil of constant volume and the coefficient of permeability for a deformable saturated soil are reviewed. A new coefficient of permeability function for a deformable unsaturated porous medium is then developed. A series of triaxial permeameter tests on unsaturated silty sand are described and the results from the experimental program are analyzed using the general form of the newly developed permeability function. The results show good agreement between the experimental data and the proposed model for a deformable unsaturated porous medium.Key words: unsaturated soil, coefficient of permeability, permeability function, soil-water characteristic curve, triaxial permeameter, deformable porous medium.

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Patil, Gudigopuram, Ayyildiz, Delgado, and Morrison. "Performance Evaluation and Dimensional Analysis of Multistage Helicoaxial Pump for Two-Phase Flow." International Journal of Turbomachinery, Propulsion and Power 4, no. 3 (July 25, 2019): 22. http://dx.doi.org/10.3390/ijtpp4030022.

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A four stage helicoaxial pump was tested under varying operating conditions. A range of inlet pressures, rotational speeds (3000, 3600 rpm), and gas void fractures (GVFs) were considered for two fluid viscosities. The head developed and power input to run the pump were recorded. Head, power input and efficiency decrease as the GVF increases with best efficiency point (BEP) moving towards lower flow rate conditions. Dimensional analysis was conducted to evaluate the applicability of current affinity laws to the two-phase flow performance of the pump under consideration. Dimensionless head coefficient and power coefficients were defined for two-phase flow, considering the homogeneity in the two-phase fluid properties. Deviations in the two-phase affinity coefficients from the common law curve increases with GVF. To bridge this gap, a new correlation is proposed with a revised flow coefficient that allows all the head coefficient data to collapse on a single line with a greater degree of accuracy.

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Bhattacharyya, Moni Mohan. "On the partitioning of the viscosity B coefficient and the correlation of ionic B coefficients with partial molar volumes of ions for aqueous and non-aqueous solutions." Canadian Journal of Chemistry 67, no. 8 (August 1, 1989): 1324–31. http://dx.doi.org/10.1139/v89-204.

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A new method of partitioning the viscosity B coefficients has been proposed on the basis of the assumption that ionic B values should be a monotonie function of crystal radii cubed, independent of the sign of the charge, for aqueous and various non-aqueous systems. Ionic B values thus obtained in different solvents by a single method of division provide a basis for uniform comparison among themselves as well as with the existing values. The usual assumption of equal contributions of K+ and Cl− ions has been discarded. The internal consistency of the derived set of Bi values is demonstrated by correlation with the ionic radii, hydrated ionic radii, partial molal volumes, temperature coefficient of equivalent conductance, and partial molal ionic entropy. The salient feature of the set of Bi values is noted by its linear relationship not only with the partial molal volumes but the same is also observed with the ionic radii of ions of different valence and charge types. Eyring's equation for viscosity using Frank–Wen's model of ion–solvent interaction has been utilised for the calculation of void viscosity and electrostriction viscosity. The latter is compared with the corresponding component of partial molal volumes using the Drude–Nernst equation based on the continuum model for solvent. Keywords: ion–solvent model, ionic B values, B coefficients, division of B coefficient, void viscosity, micro viscosity.

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Liang, Chunyu, Yinghan Wang, Guojin Tan, Lidong Zhang, Yutong Zhang, and Zhihua Yu. "Analysis of Internal Structure of Cement-Stabilized Macadam Based on Industrial CT Scanning." Advances in Materials Science and Engineering 2020 (August 27, 2020): 1–10. http://dx.doi.org/10.1155/2020/5265243.

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The composition and structure of cement-stabilized macadam (CSM) is an important factor affecting its performance. Aiming at the typical suspension dense structure and skeleton dense structure, the static pressure and vibration methods were used to prepare the CSM samples. The three-dimensional internal structure characteristics of CSM were analyzed and studied by industrial CT scanning technology. By using digital image and 3D reconstruction technology, the structural parameters such as the number of 3D voids, the gradation of voids, the distribution of voids along the height direction, and the coefficient of variation of the proportion of coarse aggregate area were obtained. The results show that more than 80% of the voids in CSM are less than 1 mm3, and the number of large voids of skeleton dense gradation is more than that of suspension dense gradation under the two compaction methods. The distribution of internal voids along the height of CSM specimens cannot be changed by the compaction mode, but the vibration method can reduce its void ratio. Under different compaction methods, the variation coefficient of the coarse aggregate area ratio of two kinds of CSM mixture generally has the same change trend, and the vibration method can make its inner structure more uniform.

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Journal articles on the topic 'Void coefficient'

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