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A point model of particle densities and temperatures within a CTR is formulated, and equilibrium solutions are obtained for different plausible operating regimes of a D-T reactor of commercial interest. The stability of these equilibrium points against excursions in the overall particle densities and temperatures is determined by linear analysis and confirmed by dynamic simulation – certain regimes are found to be unstable. Control of a CTR about an unstable equilibrium point by varying the injected ion intensity and D-T mixture is investigated and found to be difficult when the ion containment time is not large with respect to the delay time between consecutive changes in the injected ion beam.

1. The kinetics of the sintering of niobium carbide is largely determined by the presence in the latter of iron, which is picked up during milling in units with steel balls. Activated sintering was found to be exhibited by powder containing, in the starting condition, as little as 0.3 wt.% of iron. No upper limit of the activating action of iron has been established. 2. The activation of the shrinkage of specimens containing iron is induced by the formation of a liquid phase, which intensifies the processes of viscous and diffusional flow at the particle interfaces. 3. Powders of smaller particle size, too, being characterized by larger specific surface and greater particle structure defectiveness, exhibit intensified sintering.

Lunar samples may be classified as crystalline rocks, breccia (fused mixtures) and soils, the latter containing crystalline fragments, microbreccia, and glassy particles including spheres. Surface areas are smaller and pore structure is less extensive in crystalline samples. Pore and/or defect structure is considered in terms of three types of lunar events: solar wind irradiation, meteorite bombardment, and lunar volcanic action or cinder formation. The evidence presented was obtained through optical and electron microscopy as well as by adsorption studies. Pore structure is thought to be created both through particle fusion and fracture accompanying meteorite impact and (apparently more rarely) by gas evolution through solidifying molten rock.

The original morphology of polytetrafluoroethylene prepared by radiation-induced emulsion polymerization was studied by electron microscopy. The morphology depends on molecular weight, which in turn depends on polymerization conditions, especially the emulsifier concentration. The molecular weight decreases with increasing emulsifier concentration. The morphology changes with molecular weight roughly as follows: fibrils below 105, rods between 105 and 5 × 105, and granular particle above 106. The crystallinity is high for all morphologies.

Metal targets have been impacted at an oblique angle by 3 mm steel balls at velocities up to 250 ms −1 . The mechanism of metal removal has been studied in detail. The initial stage is the formation of a lip at the exit end of the crater by shearing of the surface layers. Above a critical velocity, characteristic of the particular metal, this lip is detached from the surface by the propagation of ruptures at the base of the lip. It is suggested that a similar mechanism may operate during oblique impacts by irregularly shaped particles when the angle between the leading edge of the particle and the target surface is small. It is found that material is more readily removed from work-hardened copper than from annealed copper. It is suggested that this is because in the work-hardened metal the deformation is concentrated in the surface layers, aiding the formation of a fragile lip, whereas in annealed metal the impact energy is spread through a large volume.

The distribution of the electrical charge and the charge‐to‐mass ratios of powder particles are related to the distribution of the particle radii. The latter distribution is assumed to be log‐normal and the particle charge is assumed to be quadratic in its radius. It is found that neither the microscopic average values nor the macroscopic average values are always good representations of the electrical properties of the powder sample. The variations of the average and the median values of the distributions as functions of the standard deviation of particle size are studied.

The stresses on planes within a sphere in simple flow fields are examined with a view to predicting the manner of break-up under fluid forces. The principles of powder technology are invoked in order to find likely surfaces of particle failure. A discussion is then presented of the relationship between the stresses in an ideal sphere and the reported behaviour of real particle aggregates. It is concluded that the strength of coagula and flocculated material is highly dependent on the size to which the aggregate has grown.

Abstract A mathematical procedure is given for calculating proppant concentration and final fracture shape for proppant concentration and final fracture shape for a fracture generated by injection of a viscous gel in which the propping material does not settle. To prevent bridging in the fracture, a decreasing pad prevent bridging in the fracture, a decreasing pad volume is present ahead of the proppant slurry. If combined with a criterion for proppant admittance - expressing the minimum width required for nonbridging particle transport - the developed procedure will result in a realistic design of fracturing treatments. Introduction Hydraulic fracturing is a well known technique for improving the productivity of wells by creating a highly conductive path in the reservoir. This path is made by fracturing the formation through the injection of fluid into a well at pressures above the breakdown pressure. To keep the fracture open after the treatment, propping material is injected with the fracturing fluid. Settling of the proppant can be reduced or even prevented by using viscous oil- and water-based gels as fracturing fluids.From theoretical considerations it follows that the cross-section of a propagating hydraulic fracture is approximately elliptical. The dimensions of the ellipse are determined by the injection rate, the injected volume of fracturing fluid, and fracturing-fluid properties-taking into account the volume of fluid loss to the permeable formation. The fluid loss depends partly on the fluid potential gradients at the fracture walls, resulting in a time-dependent fluid-loss coefficient, which is proportional to the reciprocal of the square root of the exposure time.Since the propping material can cause early screenout, a relatively large sand-free pad of fracturing fluid is injected to initiate the fracture. This pad volume moves ahead of the fluid (gel) containing the propping material. Owing to spurt and filtration losses - highest at the fracture tip but decreasing gradually toward the well - the pad length in the fracture will decrease. The proppant-laden fracturing fluid is also subject to fluid loss, which causes the proppant concentration to increase with distance from the well. The propped fracture width obtained after the fracturing treatment depends on the balance between pad volume and proppant concentration in the fracture. A treatment design should therefore aim at optimization of pad volume, fracturing-fluid volume, and proppant concentration. A design program should deliver practical pumping schedules, which generate fractures of required penetration and conductivity. penetration and conductivity. The present study is a new step toward a more realistic design of fracturing treatments. Differential equations describing the proppant distribution in fractures created by very viscous fluids (no settling) are derived and solved. DEFINITION OF THE MATHEMATICAL MODEL The derivation of the differential equations describing the proppant distribution is based on the following model premises.1. Vertical fractures are of rectilinear shape.2. Two symmetric fracture wings move diametrically from the well.3. Fracture dimensions follow the relations established by Geertsma and de Klerk.4. Gel and proppant move with the same velocity in a piston-like manner.5. Rheological properties of the gel prevent settling of the proppant.6. Fluid-loss is proportional to the square root of the exposure time.7. A decreasing proppant-free pad moves ahead of the proppant suspension.Based on these conditions, a set of differential equations subject to the boundary conditions has been derived (see Appendix A). In Appendix B the applied finite-difference scheme, and in Appendix C the solution procedure are discussed. To describe radial fractures, a simple coordinate transformation has been given in Appendix D. SPEJ P. 531

Effects of TiB2 and TiAl3 particles, smaller than 15μ and 600μ, respectively, on grain refining of cast structure of 99.75% and 99.99% aluminum were studied. The results obtained are as follows:1) Grain size of cast aluminum decreased when 0.01 to 0.10%TiB2 was added. This effect became more pronounced as the particle size decreased. Further, it was found that the refinement effect due to TiB2 was more effective when the temperature of molten aluminum was raised to 900°C and 0.006%Ti was added in advance.2) Similarly, grain refining effect due to TiAl3 became more pronounced as the content of TiAl3 increased from 0.07% to 0.54% and the particle diameter decreased. This effect was further noted when the holding time and the temperature of the molten metal containing TiAl3 particles increased.3) When 0.05%TiB2 and 0.016%TiAl3 were added together to the molten metals, the refinement effect was very pronounced if the particle sizes of TiB2 and of TiAl3 were less than 2μ and 100μ, respectively. This observation was consistent with the refinement effect of the Al-5%Ti-1%B master alloy on the cast structure of pure aluminum.

Studies of spouted beds of sand particles have shown that the range of particle sizes that can be spouted extends downwards to at least 90 – 150 μm, and that whether or not a bed of particles of given size can be maintained in the spouting condition is strongly dependent on the diameter of the inlet orifice.

A study was made of the effect of carboxylic monomers on the surfactant-free emulsion polymerization of styrene and styrene–butadiene. Acid monomers, such as acrylic acid, methacrylic acid, and itaconic acid, were shown to play a critical role in particle formation and particle stabilization in such systems. In the emulsion polymerization of styrene, methacrylic acid forms particles more efficiently than acrylic acid. This difference is attributed to the more hydrophobic nature of the methacrylic monomer which allows it to diffuse more rapidly to the particle surface where it acts to prevent agglomeration. The ability of carboxyl groups to orient at the particle–water interface was studied by acid–base and soap titrations of carboxylated styrene–butadiene latices. The polymerization of itaconic acid onto the particle surface of a styrene–butadiene latex produces a surface carboxyl density much higher than is obtainable with classically adsorbed surfactants. This result is used to explain the greater stability of carboxylated versus noncarboxylated emulsion polymers. During the polymerization of styrene–butadiene latices, carboxyl groups dervied from methacrylic acid are shown to be buried more deeply into the particle as compared to carboxyls derived from the more hydrophilic acrylic acid which orient more at the particle–water interface.

Studies were made of the effects of alloy composition on the mechanical behavior of as-worked W-4Re-Hf-C alloys containing up to about 0.8 mol % Hfc. Extracted second-phase particles were analyzed and related to alloy composition and creep strength. While strengthening is attributed to HfC particles, the presence of excess hafnium or carbon (above the calculated amounts for stoichiometric HfC) in swaged W-4Re-Hf-C alloys generally causes a reduction of the high-temperature (1930 C) tensile strength; maximum creep strength is, however, indicated for alloys with a slight (about 0.05 to 0.1 at. %) excess of hafnium. Particle strengthening is reduced by WC in solid solution with HfC for allow compositions with an excess of carbon. The low-temperature ductility of worked W-4Re-Hf-C alloys appears to be far more dependent on the amount of excess C or Hf present than on the HfC particle content in the range studies.

Microencapsulation of solid stearyl alcohol particles by complex coacervation was studied. Spherical particles of solid stearyl alcohol were prepared by the vibrating capillary method. Various size fractions of these particles were encapsulated by a modified technique described in an earlier report. Particle concentration and particle-size studies revealed that only a small fraction of the total amount of colloid was used in the formation of the capsule wall. Wall thickness decreased with increasing ratios of solid particles and increased as the particle diameters increased. Scanning electron micrograph observations of the surface showed that acacia was retained on the surface of particles melted and congealed in acacia solution and that the final encapsulated particles had a scaly surface appearance. The studies tended to confirm indications from earlier work that gelatin molecules interact directly with acacia on the surface of the stearyl alcohol particles to form the capsule.

Various grain boundaries were observed in KCl tablets produced by compressing the powder. A parameter c (individual confusion factor: ICF) was proposed to describe the mode of appearance of a grain boundary which is governed by the mutual orientation of the two adjacent grains. In the present paper, the ICF is defined by c=γ trg( \widehatEF,π/2), where γ is a parameter of the imperfection in the crystal particle, \widehatEF the angle between the direction E of the particle and the direction F of the stress, and trg means a triangular wave function. It is also shown that the above expression fits experimental data qualitatively.

Using a three-phase fluidized bed, the effects of particle sizes and flow rate of both liquid and gas on the bed porosity and diameter of the bubbles were studied. A comparison between the experimental value of the bed porosity and the value obtained by using the Dakshinamurty et al . equations was made.

In the approximation of multiplicativity of the binary and ternary distribution functions, Bogolyubov's method is used to calculate the chemical potentials of the cubic modifications of ammonium halides with allowance for three-particle interactions between the ions. The temperatures of polymorphic transitions are determined for different pressures together with the discontinuities of the volume and the heats of transition. The results are compared with the experimental data.

A method for the powder-metallurgy fabrication of tool-steel bar stock has been developed that requires neither isostatic compaction nor low-oxygen powders. The powder is heated in sealed steel tubes and directly step-forged to 99·5% density. Further reduction by rolling raises the density to 100%. A reducing agent and an oxygen getter are enclosed in the container, together with the powder for in situ reduction of particle surface oxides. This makes initial evacuation of the containers unnecessary and allows powders with high oxygen contents to be used. Mechanical properties compare well with those of material rolled from ingot.

Stacked chloroplast membranes isolated from Chlamydomonas reinhardtii have differentiated particle arrays when examined by freeze-fracture electron microscopy. When the membranes are isolated unstacked, these particle arrays are lost and the fracture faces have a homogeneous appearance. The changes in appearance are due to rearrangement of existing membrane components by lateral particle movements in the plane of the fluid chloroplast membranes, since quantitative measurements demonstrate almost complete conservation of numbers and sizes of membrane particles during experimentally controlled stacking and unstacking.

Channelling of fast protons in silicon and germanium crystals with surface damaged layer was studied by backscattering method. The energy spectra of the backscattered protons can be interpreted by a theory based on the particle diffusion in the transverse momentum space. It is also demonstrated that the theory is applicable to the determination of the depth distribution profiles of the lattice defects in imperfect crystals.

A study is reported on the possibility to determine the influence of particle sizes of cement on the strength of cement mortars by taking into consideration all the particles in a set, under the presumption that apart of the independent effect of every particle in the course of hydration there is a simultaneous and intermediate effect of all the particles on the same physical property. The method has been applied to cement of identical chemical and phase composition but different particle size distributions.

The kinetics of growth of theγ' precipitate in binary Ni-7, 8, 9 and 9,9 wt.% Al alloys, containing γ' volume fractions ranging from 0.09 to 0.60 at the aging temperature of 800°C, were studied by magnetic analysis and transmission electron microscopy. The coarsening of γ' precipitates in ternary Ni-16.9 wt.% Cr-3.4 wt.% Al and 14.2 wt.% Cr-4.9 wt.% Al alloys aged at 750°C was also investigated by transmission electron microscopy. These studies were undertaken to provide a critical test of a recent modification of the Lifshitz-Slyozov-Wagner theory (the MLSW theory) of diffusion-controlled particle coarsening, which predicts a pronounced effect of volume fraction on the kinetics of coarsening and on the distribution of particle sizes. The results of this study convincingly demonstrate that the volume fraction of γ' precipitate has no effect at all on its coarsening behavior. In fact, the results of the present studies are in excellent agreement with those of other investigations on these alloy systems, and therefore with the original LSW theory. The disagreement between the MLSW theory and experiment is discussed with respect to the assumptions used to characterize the problems of diffusional growth and dissolution of spherical precipitates.

The interfacial and adhesive properties of liquid-solid and solid-solid particle/substrate systems have been investigated by scanning electron microscopy. it is demonstrated that particle shapes conform to those expected on the basis of contact angle measurements, thereby confirming the shape theory of Winterbottom. The adhesive energies for Hg/Al, Hg/glass and Hg/Pd were measured as 64, 92 and 720 ergs/cm2, respectively, at 25°C. By comparison, the adhesive energies of the solid-solid systems Ni/ThO2 and stainless steel/Al2O3 were measured to be 1100 and 1440 ergs/cm2 respectively at 1200°C.

A comparison of the equilibrium vapor pressure over nitric acid solutions with observed water and nitric acid partial pressures in the stratosphere implies that nitric acid cannot be present as an aerosol particle in the lower stratosphere. A similar comparison for sulfuric acid solutions indicates that sulfuric acid aerosol particles are 75% H2SO4 by weight in water, in good agreement with direct observations. The freezing curve of H2SO4 solutions requires that the H2SO4 aerosol particles be solid or supercooled. The equilibrium vapor pressure of H2SO4 in the stratosphere is of the order of 20 picotorr. At stratospheric temperatures, ammonium sulfate is in a ferroelectric phase. As a result, polar molecules may form a surface coating on these aerosols, which may be a fertile ground for further chemical reaction.

The rate of moisture transfer through a peanut oil film was measured. It was found that the rate can be expressed by the equation: r = [k a1 (Δ a)]/t where r is the rate in g water/cm2/day, a1 is the higher water activity, Δ a is the difference in the water activity across the barrier, t is the film thickness and k is a constant. This principle was extended to fat-humectant systems where the lower water activity phase is intimately distributed through the fatty medium such as peanut butter and chocolate liquor. Doubling the fat content should increase the film thickness around each particle by 2 and halve the transmission rate as was found experimentally.

In the studies of pigment volume effects in paint films, particle packing has been shown to be very important. The effects of particle size distribution on this packing has been known but has received little quantitative consideration. In this paper we consider the packing of real and model continuous distributions of particle sizes. An extension of an algorithm for the calculation of random densest packing is given which applies to continuous distributions. Using a log-normal distribution as a model, the effect of the width of a single distribution on packing is considered. Mixtures of distributions are also considered with the calculation of packing efficiency as a function of mean size ratio and distribution widths. Maxima are shown to occur in the packing efficiency of mixtures of distributions as a function of the volume fractions of the individual distributions. The implications of these packing variations in real systems are then discussed.

The model assumes the freeze-drying particles to be spherical and that a dry layer of uniformly and gradually increasing thickness is formed as the drying proceeds. The model embodies the concept of porous system for computing the thermal conductivity and permeability of the dry layer. With this model it is possible to predict the residence time and residence height necessary for the freeze-drying of spherical particles.

Five different fine powders with average particle size of about 100 microns or smaller were fluidized with air over their respective bubblefree ranges of fluidization. Photographs taken through the front transparent wall of the column showed that the beds contained cavities and microchannels whose sizes were of the same order of magnitude as the particle size. It is shown that interparticle van der Waals adn capillary forces play an important role in the bubble-free expansion of small particles. Measurements of bed expansion and average particle drag coefficients are consistent with the proposed role of interparticle forces.

A method of calculation is presented for the yield of an electron excitation process by a channelled particle in a single encounter with an atomic row or plane in a crystal. It is shown that, if ψ is the initial angle between the ion trajectory and the row or plane, the number of inner-shell electrons excited is an increasing function of ψ whereas the number of outer electrons excited may decrease with increasing ψ.

The relation between viscous and diffusive deformations is discussed, and their nonequivalence is emphasized. Molecular theories relating self diffusivity to viscosity, as well as the macroscopic behavior of materials deforming by diffusive creep and by viscous flow, are reviewed. It is concluded that while molecular theories can properly relate viscosity to diffusivity, viscous flow and diffusive creep are not macroscopically equivalent. A “viscosity” obtained by equating a diffusive creep flow to a viscous flow will in general depend upon the state of stress and will therefore not be a material property. The differences between the flow types are illustrated with two examples, the spheroidization of a nearly spherical particle, and the effective viscosity of a suspension of particles in viscous liquid.

Four grades of coamercially available microcrystalline cellulose have been examined and the appearance, particle size distributions, specific surface areas, pore size distributions and surface energies determined. The median Stokes diamsters ahow general correlation with published data, but Coulter counter results are larger by a factor of approximately 1.4. Correlation is also seen with values obtained from air permeametry experiments.Scanning electron-microscopy demonstrated the presence of two general types of particle, one roughly rod-like and the other an irregular mass. At higher magnifications, fully hydrolysed samples show a microfibrillar structure, the individual fibrils possessing a transparent longitudinal axis. The possibility that the fibrils are hollow is confirmed by analysis of the adsorption isotherms using mathematical models which indicate that the materials are porous, With a modal radius value of about 2.0 nm.

Holograms of fogs produced in a high-altitude propeller test cell were recorded in the following condition: Pressure 0,5 atm; temperature 0 °C; velocity of the fog 100 m/s. The droplet diameters ranged between 5 and 50 μm. Reconstructed images were enlarged X 1000 and visualized with the help of a TV-system. Individual measurements on the particules porvided the local concentration and diameter repartition. Moreover, the use of double-pulse holography gives the three components of the speed vector for each particle. The optical arrangement and apparatus are described. The influence of experimental parameters upon the precision of measures is discussed.

This paper shows the type of development that has occurred over recent years in tantalum capacitors, with particular reference to the sintered tantalum powder – liquid electrolyte (wet Ta) system. In the ‘wet’ system, the various defects that arise, such as silver migration, scintillation and field crystallisation, are illustrated and the effect of improvement in initial particle shapes on final surface area is considered.

For rapid reactions the differences in local coefficients of heat and mass transfer around the surface of a catalyst particle lead to a distribution of surface temperatures and an asymmetric internal profile. The nature of these distributions and their changes with flow rate were predicted for the hydrogenation of ethylene on a single spherical pellet of nickel on silica alumina. The measured surface and internal temperature were in good agreement with the predictions.

Electron microscope observations of the lateral surface of NaCl ingots pulled by the Czochralski technique reveal carbon particles incorporated in the crystal during the melt growth as well as small NaCl crystallites formed in the vapour and deposited subsequently onto the surface.

Aluminum fine particles of free surfaces were made by the evaporation method in helium gas to investigate the relation between the superconducting transition temperature Tc of the fine particle and its size. The fine particles were collected without exposure to the air to obtain clean surfaces, however, this process introduced some undesirable weak contacts among the particles. The size distribution was determined by means of electron micrographs, and the average diameter ranged from 90 to 160 A. The superconducting transition temperature Tc was determined from the change of diamagnetic susceptibility with temperature. The present experiment shows that Tc rises with a decrease in , and becomes about 1.8 K for of 90 A, considerably higher than that of bulk aluminum 1.16 K.

The dielectric constant of compressed powders of KDP and Rochelle salt has been measured st 1 MHz as a function of particle sizes ranging from 20µ to 600µ over a wide temperature range to cover ferro and paraelectric phases. Dielectric anomalies indicating the ferroelectric behaviour in both KDP and Rochelle salt powders are observed upto 20µ particle size. The existence of ferroelectricity was further confirmed by observing ferroelectric hysteresis loops. The measured values of the dielectric constant in Rochelle salt were independent of particle size while in KDP they decreased with decreasing particle size. The experimental values are compared with the values calculated by modified Bruggeman's formula. It is found that the agreement in theoretical and experimental values in Rochelle salt was with in 25%. In KDP the agreement between experimental and theoretical values was poor and the measured values were less than 1/4th of the calculated values.

Results are presented of experiments that compare the performance of three ceramic-Ag contact materials (TiC-Ag, TiB 2 -Ag and NbC-Ag) with the well known WAg contact material. The conductivities of the ceramic-Ag contacts were found to be comparable to that of W-Ag. Erosion measurements in an 880 A 440 V rms circuit showed that the rate of erosion was not a simple function of the ceramic material's heat of evaporation. The erosion mainly occurred through evaporation with some particle ejection in case of the W-Ag and NbC-Ag materials. The ceramic-Ag materials performed well when subjected to testing in a 100 A low voltage circuit breaker. A microstructural evaluation revealed that the contacts could have been improved by lowering the surface tension between the ceramic and silver to achieve better wet- ting.

Correlatios between the dispefsion state of palladium on, zeolite Y and their catalytic activities were studied. Palladium catalysts on zeolite Y were prepared by calcinations of Pd(NH8)2+-NaY in a1r and subsequently reducing in hydrogon strea. An electron microscopy was used to determine the size distribution, the average diameter of palladium particles and the number of palladium particles per unit are. The fact was revealed that the size distribution of palladium particle was controlled by the calcination temperature. The catalytic activities of these catalysts for dehydrogenation of cyclohexane were reasonably interpreted in terms of the total surface area of palladium particles per unit area of zeolites. For oxidation of propylene In the presence of steam, however, this interpretation was not applicable. Some informations on the mechanism of agglomeration of palladium ions on zeolite Y were obtained by the use of differential thermal analysis and X-ray diffraction method.

The deposition of aerosol particles on swarms of accelerating spherical glass beads was studied over a range of aerosol particle sizes and air velocities, and two glass bead sizes. The results were interpreted by a theoretical model which was based on equations valid for inertial impaction and interception of spheres on single, stationary spheres, and which included an empirical factor dependent on the volumetric concentration of the collection particles.

1. A study was made of the compressibility and sinterability of KhN55VMTFKYu-alloy powders produced by: 1) processing waste machining swarf, 2) simultaneously reducing a mixture of oxides and metal powders with calcium hydride, and 3) atomizing an alloy melt and subsequently reducing the powder with calcium hydride, 2. The KhN55VMTFKYu-alloy powder obtained from swarf was found to have the poorest compressibility; thanks to its well-developed particle surfaces, however, it had the best compactibility. 3. The most effective protective atmosphere for the sintering of KhN55VMTFKYu-alloy powders is hydrogen with a dew point of between −30 and −40‡C, used in conjunction with Koreks packing material and a titanium sponge getter. 4. The KhN55VMTFKYu-alloy powder obtained from swarf was found to be superior in sinterability to the other two types of powder studied. 5. Virtually nonporous compacts from the KhN55VMTFKYu-alloy powders were produced by hydrostatic pressing under pressures in excess of 90 kg/mm2 and sintering at 1300‡C.

The hot wire method has been used to measure thermal conductivity of massive solid materials. In order to find out a suitable way to measure thermal conductivity of granular solid materials, Ks, by hot wire method, the authors have examined the thermal conductivity measurement about the system of dispersed granular solid materials into a solid dispersion medium like silicon rubber. However, there were some limitations in the method that silicon rubber didn't work well at higher temperatures than 300°C and the rubber penetrated into the pore of granular solid materials in some cases. In this research, the authors tried to use some fluids to be applicable at higher temperatures and not to react with granular solid materials, and developed a method to be able to calculate Ks from gross thermal conductivity of granular solid-fluid mixture, K, and that of Kf.For the calculation of Ks from K and Kf, de Vries'equation was reasonably applied to both spherical and irregular-shaped particles. The shape factors Gi included in de Vries'equation were found to vary with the surface area of the granular solid materials in the case of spherical particles, but was almost constant in the irregular shaped particles.They wereG1=G2=5.34×10-4S+0.0374 G3=-1.07×10-3S+0.925} for spherical particle, G1=G2=0.05, G3=0.90 for irregular shaped particle, where S is surface area (cm2/cm3)The reliability of the results obtained by the application of de Vries' equation increased with the use of fluid having higher thermal conductivity. For example, when helium gas with thermal conductivity of 3.65×10-4cal/cm⋅sec⋅°C was used, the error of the obtained values Ks of 3.25×10-3 and 1.4×10-2cal/cm⋅sec⋅°C were about 4% and 8%, respectively.In view of the fact that the error increased with increasing thermal conductivity of granular solid materials to be measured, this method can be applied to the solid materials having thermal conductivity of smaller than about 1.5×10-2cal/cm⋅sec⋅°C, if the error of ±10% is allowable.

A simple physical model describing the axial transport of dry particulate solids through horizontal, rotating cylinders has been investigated. Design equations are presented which relate particle hold-up in the cylinder to mass flow rate as a function of the cylinder dimension and speed of rotation. Both open-ended cylinders and cylinders with a central overflow discharge have been studied. An empirical expression has been obtained which describes the resistance to flow offered by the discharge plate as a function of the size of the discharge opening and the mass flow rate through the cylinder. Experimental verification of the physical model has been obtained on a laboratory scale for a variety of operating conditions.

The tensile and fatigue properties of rods which were extruded from Zn-ZnO powder composites were determined at temperatures between 150°C and −196°C. Different particle sizes were used in the powders and the amount of 02 was varied from 0.12 to 1.71 weight per cent (w/o): The effect of ball-milling the powder prior to compaction was also studied.In general, the specimens of powder origin were stronger than fine-grained pure zinc and those made from powder containing very small particles (∼3 μm) displayed good ductility, particularly at room temperature. However, they possessed poor work-hardening properties so that the UTS was never more than 4000 psi above the 0.2% proof stress. Specimens of ball-milled powder origin were stronger and more brittle than other specimens. The superior tensile strengths of the powder composites over pure zinc were reflected by superior fatigue (push-pull) properties. The improvement at higher temperatures is surprising, in view of the very fine grain size of the com...

The results of an exploratory investigation of the application of laser anemometry to the measurement of instantaneous velocity within industrial flames is reported. A laser anemometer was used to assess the viability of measurements within the 2 m-sq experimental furnace of the International Flame Research Foundation. Measurements were carried out, in the forward scattering real fringe mode, in a hot furnace without combustion and in gas, oil, and coal flames. The particle concentration was observed for each flow configuration and, where possible, the mean velocity value obtained from the laser anemometer was compared with that from a water cooled pitot probe. On the basis of this investigation, the value of laser anemometry to the improvement of furnace design is discussed.

By the addition of KOH solution to FeSO4-Cr2(SO4)3 mixed solution, Fe(OH)2 was formed and it was oxidized to Fe3O4 by air. The heat treatment of formed Fe3O4 precipitate was carried out in vaccum (10-5 Torr) and in H2-H2O mixed gas (H2O/H2=2) at 200-500 C for 5 hrs.The effects of the heating temperatureon particle size, surface area and pore structure (pore distribution, pore diameter, pore volume) were investigated by means of X-ray diffraction, electron microscopy and gas adsorption.Addition of Cr(III) suppressed the particle growthof Fe3O4 and also increased the surface area remarkably.By the heat treatment of the precipitate; 1) The particle growth of Fe3O4 occurred slightly at temperatures above 400 C, 2) The surface area changed with rise in temperature, that is, the area increased with temperature up to about 300 C and showed a maximum at this temperature. Above 300 C, however, the area decreased. The increase in surface area was caused by micropore (diameter lt 50 A) resulting from the removalof water contained, and the decrease was caused by the pore-widening process resulting from sintering of the precipitate at temperatures above 400 C, 3) The changes of particle size, surface area and pore structure were also affected by heating atmosphere.