scholarly journals The volume fraction method for the evaluation of kidney: A stereological study

2009 ◽  
Vol 50 (1) ◽  
pp. 233-239 ◽  
Author(s):  
Gulsun PAZVANT ◽  
Bunyamin SAHIN ◽  
K.Oya KAHVECIOGLU ◽  
Halil GUNES ◽  
Nazan GEZER ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Fraction Method

Theoretical Analysis of CFD-DEM Mathematical Model Solution Change With Varying Computational Cell Size

2018 ◽  
Author(s):  
Annette Volk ◽  
Urmila Ghia
Keyword(s):  
Mathematical Model ◽  
Standard Deviation ◽  
Cell Size ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Independent Solution ◽  
Model Verification ◽  
Computational Cell ◽  
Drag Laws ◽  
Fraction Method

Successful verification and validation is crucial to build confidence in the application of coupled Computational Fluid Dynamics - Discrete Element Method (CFD-DEM). Model verification includes ensuring a mesh-independent solution, which poses a major difficulty in CFD-DEM due to the complicated solution relationship with computational cell size. In this paper, we investigate the theoretical relationship between the solution and computational cell size by tracing the effects of a change in cell size through the mathematical model. The porosity profile for simulations of fixed-particle beds is determined to be Gaussian, and the average and standard deviation of the representative distribution are reported against cell size. We find the standard deviation of bed porosity increases exponentially as the cell size is reduced, and the drag calculations are very sensitive to changes in the porosity standard deviation, resulting in an exponential change in expected drag when the cell size is small relative to the particle diameter. The divided volume fraction method of porosity calculation is shown to be superior to the centred volume fraction method, as it reduces the porosity standard deviation. The sensitivity of five popular drag laws to changes in the porosity profile is presented, and the Ergun and Beetstra drag laws are shown to be the least sensitive to changes in the cell size.

scholarly journals Measurement of tumor interstitial volume fraction: Method and implication for drug delivery

2004 ◽  
Vol 52 (3) ◽  
pp. 485-494 ◽  
Author(s):  
Y.R. Kim ◽  
M.D. Savellano ◽  
D.H. Savellano ◽  
R. Weissleder ◽  
A. Bogdanov
Keyword(s):  
Drug Delivery ◽  
Volume Fraction ◽  
Interstitial Volume ◽  
Fraction Method

Rheological Characteristics of Nanoparticle Compound Microencapsulated Phase Change Material Suspension

2009 ◽  
Author(s):  
Liang Wang ◽  
Guiping Lin ◽  
Yulong Ding
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Volume Fraction ◽  
Rheological Characteristics ◽  
Effective Volume ◽  
Effective Volume Fraction ◽  
Microencapsulated Phase Change Material ◽  
Change Material ◽  
Fraction Method

Microencapsulated phase change material (MPCM) suspensions have large specific heat due to the latent heat of the phase change material and enhance the convective heat transfer consequently. However low thermal conductivity of the phase change material diminishes the heat transfer performance of the MPCM suspensions. To improve the thermal conductivity of the MPCM suspensions, TiO2 nanoparticles were added into the MPCM suspensions to formulate a novel thermal fluid—nanoparticle compound microencapsulated phase change material suspensions. In this paper, the rheological characteristics and shear viscosities of such slurries using a Bolin CVO rheometer (Malvern Instruments) over a range of shear rate (5–500s−1), MPCM concentration (0–20wt%) and TiO2 nanoparticle concentration 0.5wt% at temperature (20°C–40°C). The result shows that the viscosities of NCMPCM suspensions are almost independent of the shear rate, indicating Newtonian fluid under the conditions of this work and the viscosities depend strongly on temperature which fits well with the VTF function. Based on the effective volume fraction method and Vand equation, two methods that predict the viscosity of nanoparticle compound microencapsulated phase change material suspensions was analyzed and the result shows that the prediction data the effective volume fraction method fit the measurements well.

Experimental-theoretical predictions of stress–strain curves of Glare fiber metal laminates

2017 ◽  
Vol 52 (1) ◽  
pp. 109-121 ◽  
Author(s):  
Hale Ergun ◽  
Benjamin M Liaw ◽  
Feridun Delale
Keyword(s):  
Volume Fraction ◽  
Tensile Tests ◽  
In Situ Stress ◽  
Fiber Metal Laminates ◽  
Stress Strain ◽  
Empirical Parameter ◽  
Metal Volume ◽  
Fiber Metal ◽  
Metal Volume Fraction ◽  
Fraction Method

Monotonic tensile tests are conducted on seven different Glare grades of fiber metal laminates. In-situ stress–strain curves of glass/epoxy laminate interleaved in Glare 2(3/2) are exposed with the application of metal volume fraction method using the stress–strain curves of Glare 2(3/2) and Aluminum 2024-T3 in unidirectional and transverse directions. The strain–stress curves of cross-ply Glares are predicted by the modification of this method with an empirical parameter and a second parameter considering the relative glass/epoxy laminate thickness ratios of Glare grades. Modified metal volume fraction method presented in this study can be used as a preliminary estimation of stress–strain curves of multiple possible fiber metal laminate configurations without testing.

Chemical partitioning of elements in Ni-base MC-carbide reinforced eutetic superalloys

1983 ◽  
Vol 41 ◽  
pp. 250-251
Author(s):  
E. F. Koch ◽  
E. L. Hall ◽  
S. W. Yang
Keyword(s):  
Alloy Composition ◽  
Volume Fraction ◽  
Lattice Mismatch ◽  
Turbine Blades ◽  
Eutectic Alloys ◽  
Alloy Matrix ◽  
X Ray ◽  
Gas Turbine Blades ◽  
Analytical Electron ◽  
Analytical Electron Microscope

The plane-front solidified eutectic alloys consisting of aligned tantalum monocarbide fibers in a nickel alloy matrix are currently under consideration for future aircraft and gas turbine blades. The MC fibers provide exceptional strength at high temperatures. In these alloys, the Ni matrix is strengthened by the precipitation of the coherent γ' phase (ordered L12 structure, nominally Ni3Al). The mechanical strength of these materials can be sensitively affected by overall alloy composition, and these strength variations can be due to several factors, including changes in solid solution strength of the γ matrix, changes in they γ' size or morphology, changes in the γ-γ' lattice mismatch or interfacial energy, or changes in the MC morphology, volume fraction, thermal stability, and stoichiometry. In order to differentiate between these various mechanisms, it is necessary to determine the partitioning of elemental additions between the γ,γ', and MC phases. This paper describes the results of such a study using energy dispersive X-ray spectroscopy in the analytical electron microscope.

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

Formation of Persistent Slip Band in Fatigued Copper Single Crystals

1982 ◽  
Vol 40 ◽  
pp. 470-471
Author(s):  
N. Y. Jin
Keyword(s):  
Volume Fraction ◽  
Fatigue Cracks ◽  
Wall Structure ◽  
Matrix Structure ◽  
Dislocation Dipole ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
The Matrix ◽  
Hard Shell ◽  
Copper Single Crystals

Localised plastic deformation in Persistent Slip Bands(PSBs) is a characteristic feature of fatigue in many materials. The dislocation structure in the PSBs contains regularly spaced dislocation dipole walls occupying a volume fraction of around 10%. The remainder of the specimen, the inactive "matrix", contains dislocation veins at a volume fraction of 50% or more. Walls and veins are both separated by regions in which the dislocation density is lower by some orders of magnitude. Since the PSBs offer favorable sites for the initiation of fatigue cracks, the formation of the PSB wall structure is of great interest. Winter has proposed that PSBs form as the result of a transformation of the matrix structure to a regular wall structure, and that the instability occurs among the broad dipoles near the center of a vein rather than in the hard shell surounding the vein as argued by Kulmann-Wilsdorf.

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