Average Bulk Density Research Articles

遠心力によるサイロおよび円筒内の粉体の圧密

This study discusses the compression behavior of a cohesive powder by centrifugal force in a storage container that rotates horizontally. The stresses and the bulk density of the powder in the storage container were numerically calculated using the force balance acting on an elemental slice of powder layer and the flow properties of powder. Experiments were also carried out with kaolin powder using a cylinder or a silo with a diameter of 40mm under centrifugal force 100 to 1000 times the gravity. The powder bed was gradually compressed and was fully compressed within 10 minutes. The accuracy of the prediction by the present model is ±3% compared to the average bulk density of the powder measured by the compression experiments.

Effect of Operating Parameters on the Spray Drying of Tomato Paste

The production of tomato powder from tomato paste using the spray drying technique has been investigated in this work. The influence of a number of process variables, namely, feed total solids, feed flow rate, feed temperature, air temperature, air flow rate, and starch addition on the physical properties of spray-dried tomato powder was investigated. The product properties studied were total solids, average particle diameter, bulk density, and solubility. The increase in the feed total solids increased tomato powder total solids, particle size and bulk density and decreased its solubility, while the increase in the feed flow rate decreased tomato powder total solids and solubility, and increased the average particle size and bulk density.

Gamma-ray computed tomography to characterize soil surface sealing

The application of sewage sludge as a fertilizer on soils may cause compacted surface layers (surface sealing), which can promote changes on soil physical properties. The objective of this work was to study the use of gamma-ray computed tomography, as a diagnostic tool for the evaluation of this sealing process through the measurement of soil bulk density distribution of the soil surface layer of samples subjected to sewage sludge application. Tomographic images were taken with a first generation tomograph with a resolution of 1 mm. The image analysis opened the possibility to obtain soil bulk density profiles and average soil bulk densities of the surface layer and to detect the presence of soil surface sealing. The sealing crust thickness was estimated to be in the range of 2–4 mm.

Fabrication of carbon/carbon composites by an electrified preform heating CVI method

Carbon/carbon composites are manufactured using the electrified preform producing directly heat CVI process. The preforms are prepared by laminating the carbon fiber felts with crossply reinforcement, and infiltrated with carbon using natural gas or propylene as a reactant, with nitrogen as diluent at atmospheric pressure. The relations between the resistivity of samples and infiltration time are determined under the operating conditions. The results indicate that the preforms have gained a high infiltration rate by this technology, and the samples have higher densities using natural gas rather than propylene. Their highest average bulk densities are up to 1.71 g/cm 3 after the preforms of 1100×500×35 mm size have been densified for 80 h using natural gas. The carbon fibres in the preforms have not been damaged by this technology as yet, and the composites prepared have sufficiently high flexural properties. As the brake angular velocity is increased with the constant brake moment inertia and specific pressure, the average coefficient of friction for the composites prepared using natural gas is linearly and greatly decreased, but the variations of the brake moment inertia have a slight influence on the average coefficient of the friction when the brake angular velocity and specific pressure are kept constant. Their average thickness wear is 13×10 −4 mm/surface per stop.

Reactive sintering of boron-doped Ni76Al24 intermetallic

A preliminary investigation into the formation of boron-doped nickel-rich Ni3Al with boron additions up to 2 wt% (i.e. to levels above the equilibrium solid solubility limit of boron in Ni3Al) from elemental powders by reaction synthesis was carried out. The application of reaction synthesis was seen as a low-energy alternative to the production of Ni3Al/boride composite suitable for wear applications. X-ray diffraction, Neutron diffraction, SEM/EDS,WDS, Image analysis, Archimedes principle and Rockwell hardness measurements; were used to study the effect of boron addition on the final microstructure, average grain size, bulk density and hardness of as-prepared Ni76Al24. Up to 0.3 wt% boron content, the microstructure consisted of single-phase Ni3Al, however, at a boron content of 0.5 wt% an apparent transition from a single phase microstructure to a two-phase intermetallic/boride composite microstructure was observed, which dominated when the boron content increased, up to 2 wt%. The two-phase microstructure was identified as Ni3Al (particles) within an Ni41Al5B12 boride matrix, with no remaining un-reacted boron. The boron addition was found to increase the Rockwell hardness of Ni3Al via two mechanisms. Below the solubility limit, the increase in hardness was due to solution hardening. Above 0.5 wt%B, solution hardening in addition to the formation of the harder boride phase, were found to amount to up to 50% increase in the hardness compared with boron free Ni3Al. The extrusion of semi-molten beads at the surface of the compact at high B-content may be a limiting factor, in the formation of Ni3Al/boride composites via this route.

Bulk density of ordinary chondrite meteorites and implications for asteroidal internal structure

Abstract— The bulk densities of 82 samples of 72 ordinary chondrites (OCs) were measured to an accuracy of ∼1% using a modified Archimedian method. We found the average bulk density to be 3.44 ± 0.19 g/cm3 for the H group, 3.40 ± 0.15 g/cm3 for the L group, and 3.29 ± 0.17 g/cm3 for the LL group (± represent 1σ). Bulk density measurements of 11 pieces of one fall, Pultusk (H group), were also found to vary considerably (3.31 to 3.63 g/cm3). To investigate controls on bulk density within the OCs, we compared density with bulk chemical composition (the ratio of Fe metal to total Fe; the ratio of total Fe to SiO2; the ratio of FeO to total Fe and MgO). Within each OC group, bulk chemical composition is nearly invariant whereas bulk density varies from about 3.0 to 3.8 g/cm3. Slight but systematic differences in average density between the H, L, and LL groups presumably relate to differences in metallic Fe abundance. However, considerable overlap between OC groups and the wide range of bulk densities within each group suggest differences in porosity dominantly control variations of density within the OC subgroups.

Propriedades hidráulicas de um solo não saturado utilizando-se o permeâmetro a disco

No presente trabalho foram determinadas as propriedades hidráulicas condutividade, (K) e sorvidade, (S). Os valores destas propriedades foram obtidos a partir de experimentos com o permeâmetro a disco (r = 0,125 m), nas profundidades de 0,20 m e 0,40 m, em Piracicaba, SP. O solo é classificado como Terra Roxa Estruturada latossólica, de densidade 1500 kg m-3, a 0,20 m, e de 1540 kg m-3, a 0,40 m, com texturas franco-argilosa e argilosa, respectivamente. Para a determinação da condutividade hidráulica, K, utilizou-se a equação de Wooding, enquanto a sorvidade, S, foi determinada a partir da regressão da porção linear do gráfico da infiltração acumulada (I) versus a raiz quadrada do tempo (t½). Os valores obtidos da variação de umidade e da sorvidade refletem a alteração das condições iniciais do solo, tais como umidade inicial e estrutura superficial. Como esperado para um solo mais denso, para a profundidade de 0,40 m, os valores encontrados foram menores que os obtidos para 0,20 m. O solo, a esta profundidade, possui características estrutural e textural bem diferentes das de 0,20 m, com a sua superfície apresentando-se bastante endurecida, com grandes volumes mais adensados, formados por blocos compactados, entremeados por porções mais soltas.

00/02712 Education for photovoltaics and solar energy

The impact of scaling on off-state current of p-i-n diodes is studied. A sub-micron p-i-n diode exhibits a dominating surface component of leakage current. Variation in i-layer thickness has an impact on bulk leakage. Bulk leakage scales with cross-sectional area of the diode and surface leakage has been controlled using surface treatments to give ultra low leakage currents of 210 fA for a device of cross sectional area of 0.44 μm2. Devices of 100 nm i-layer thickness show an average bulk and surface current densities of 100 mA/cm2 and 150 fA/μm, respectively.

Polycrystalline silicon produced by Ni–silicide mediated crystallization of amorphous silicon in an electric field

Crystallization of amorphous silicon (a-Si) by Ni–silicide mediated crystallization (SMC) has been studied in an electric field with Ni area density between 3.3×1013 and 5.7×1014 atoms/cm2 on the a-Si. The needlelike crystallites of ∼1000 Å in width and several micron length grow in the 〈111〉 directions with the 〈011〉 normal to the film surface when Ni area density was between 5.1×1013 and 2.9×1014 atoms/cm2. However, dendritic crystallites have been found in the a-Si matrix without complete crystallization of the a-Si when the Ni area density was 3.3×1013 atoms/cm2. The field-effect mobility of the thin-film transistor using the SMC poly-Si was 60–112 cm2/V s when the average Ni bulk density in the poly-Si was around 3.0×1018 atoms/cm3, and it decreases with increasing Ni density.

Mutual Eclipse Events in Asteroidal Binary System 1996 FG 3: Observations and a Numerical Model

We report the CCD observations of the Apollo-type asteroid 1996 FG 3 obtained in April 1996 and December 1998. The lightcurves show a double periodicity which, following Pravec et al. ( IAU Circ. 7074, 1998), is interpreted as the signature of mutual eclipses and occultations between a non-synchronous, slightly elongated central body and its satellite. We derive a period of rotation of 3.595±0.002 h for the central body, while the orbital period of the satellite is determined to be 16.15±0.02 h. A numerical model has been developed which describes the binary system as consisting of two co-orbiting ellipsoids. The model incorporates the effects of shadowing and makes use of the Hapke photometric function. A fit of the model to the observations produces synthetic lightcurves which accurately reproduce the amplitudes, the timing, and subtler features of the eclipse events. Two possible orientations of the orbital plane normal vector (J2000) are found which can account for the observed events, one retrograde and one prograde—λ 1=282°±10°; β 1=−87°±3 and λ 2=262°±10°; β 2=+75°±3°—where the retrograde one provides a slightly better fit to the observations. We find a circular orbit normalized radius R=2.9±0.1 and primary body normalized semiaxes A=1.05±0.02, B=0.95±0.02, C=0.70±0.10. For the secondary body we find normalized semiaxes a=0.32±0.03 and b=0.23±0.03. The satellite shortest semiaxis c is not well constrained by the observations and therefore we assumed c= b throughout the modeling procedure. We also find indications that the primary body might have albedo variations across its surface. The estimated parameters allow us to determine an average bulk density of 1.4±0.3 g cm −3 which is highly suggestive of a rubble pile structure. The primary body shape, together with its spin rate, are not compatible with a hydrostatic equilibrium figure.

Microwave sintering and mechanical properties of Y-TZP/20 wt.% Al 2O 3 composites

Y 2O 3-stabilized t-ZrO 2 (Y-TZP)/20 wt.% Al 2O 3 composites were fabricated using microwave (MW) and conventional sintering techniques at temperatures in the 1200–1500°C range. A considerable difference in the densification behavior between conventional and microwave sintered specimens up to 1300°C was observed. The microwave sintered composites attain a bulk density ∼97% theoretical density (T.D.) at 1200°C, while the conventional fired materials attain only ∼95% T.D. at 1500°C. The average bulk density of the specimens, made by microwave sintering at 1500°C, was ∼99% T.D. At a given sintering temperature, microwave fabricated composites exhibited superior bending strength, fracture toughness and Vickers hardness when compared with conventionally sintered materials. For example, the composites fabricated at 1500°C exhibited a K IC of ∼7.7 MPa m and bending strength of ∼990 MPa. For comparison, specimens made by conventional sintering exhibited K IC of ∼6.5 MPa m and bending strength of ∼820 MPa. This is due to a better densification of the MW-sintered specimens.

Pore structure analysis of swollen dextran-methacrylate hydrogels by SEM and mercury intrusion porosimetry.

The objectives of this study were to visually examine the surface and interior morphology of a new class of biodegradable hydrogels based on dextran-methacrylate and to quantify the porous structure of these hydrogels in swollen state. Two techniques (scanning electron microscopy and mercury intrusion porosimetry) were used to analyze pore structure of dextran-methacrylate hydrogels as a function of the degree of methacrylate substitution. SEM was used to observe 3-dimensional network structure of cryofixed and fractured swollen dextran-methacrylate hydrogels. Image analysis of the SEM data revealed different pore shapes and sizes, depending on the degree of substitution and the location within the hydrogel. A higher methacrylate-substituted dextran hydrogel showed a compact and rigid pore structure, while a lower substituted hydrogel showed a delicate and fragile pore structure. Mercury intrusion porosimetry analysis of the pore structure of dextran-methacrylate hydrogels provided useful and more reliable quantitative data of pore characteristics, such as total pore area, average pore diameter, their distribution, and bulk density. The total pore area and average pore diameter of swollen dextran-methacrylate hydrogels decreased with an increase in degree of methacrylate substitution, while bulk density increased with an increase in degree of substitution.

Pore structure analysis of swollen dextran-methacrylate hydrogels by SEM and mercury intrusion porosimetry

The objectives of this study were to visually examine the surface and interior morphology of a new class of biodegradable hydrogels based on dextran-methacrylate and to quantify the porous structure of these hydrogels in swollen state. Two techniques (scanning electron microscopy and mercury intrusion porosimetry) were used to analyze pore structure of dextran-methacrylate hydrogels as a function of the degree of methacrylate substitution. SEM was used to observe 3-dimensional network structure of cryofixed and fractured swollen dextran-methacrylate hydrogels. Image analysis of the SEM data revealed different pore shapes and sizes, depending on the degree of substitution and the location within the hydrogel. A higher methacrylate-substituted dextran hydrogel showed a compact and rigid pore structure, while a lower substituted hydrogel showed a delicate and fragile pore structure. Mercury intrusion porosimetry analysis of the pore structure of dextran-methacrylate hydrogels provided useful and more reliable quantitative data of pore characteristics, such as total pore area, average pore diameter, their distribution, and bulk density. The total pore area and average pore diameter of swollen dextran-methacrylate hydrogels decreased with an increase in degree of methacrylate substitution, while bulk density increased with an increase in degree of substitution. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 53: 258–266, 2000

Multiparameter radar and in situ aircraft observation of graupel and hail

Documenting simultaneous multiparameter radar observations of precipitation in conjunction with in situ hydrometeor sampling is important for the interpretation of multiparameter radar observations. In situ observation using aircraft-mounted probes is one of the best ways to collect such data. In situ observation of hail and graupel in convective storms is complicated due to adverse environment of flight and low concentration of large particles that are difficult to sample. This paper presents one of the first observations of simultaneous multiparameter radar observations and in situ samples of wet hail and graupel in convective storms. The observations are unique because of the excellent coordination between aircraft samples and radar scanning, as well as relatively large sample volumes of aircraft data. Multiparameter radar observations (namely reflectivity, differential reflectivity, linear depolarization ratio, copolar correlation coefficient, and specific differential phase) are documented in graupel and wet hail. The observations indicate that the linear depolarization ratio and copolar correlation measurements, in conjunction with reflectivity levels, can be used to distinguish between graupel and hail. A simple procedure is developed to estimate the average bulk density of graupel and wet hail, comparing radar and in situ observations.

Crustal structure in the northern North Sea: an integrated geophysical study

Abstract This study focuses on the deep structure of the Viking Graben and adjacent areas of the northern North Sea (60–62°N), and its implications for the amount, timing and nature of lithospheric extension. Two regional transects have been constructed based on an integrated analysis of deep seismic reflection and refraction data, gravity and magnetic data, and correlations between offshore and onshore geology. The shallow interpretation is based on high-quality conventional seismic reflection data calibrated against a large number of exploration wells. The new and partly reprocessed seismic data, combined with the other geophysical data, make possible a better documentation of the crustal configuration, such as the pre-Jurassic sediment distribution, basement and Moho relief, and deep fault geometries. A lower-crustal body characterized by an 8+ km s −1 velocity and an average bulk density of 2.95 g cm −3 is present beneath the Horda Platform. This body probably represents a deep crustal root of partially eclogitized rocks that formed during the Caledonian orogeny. Heterogeneities within this body give rise to the non-typical velocity-density relation. The crust-mantle boundary is located at the base of this body at a depth of 30–35 km and does not coincide with the seismically defined Moho. The geometry of crustal thinning reflects the cumulative effect of several post-Caledonian rift phases. Results show that Permian rifting affected a wide area, from the Øygarden Fault Complex to the Hutton Fault.

Factors influencing cattail abundance in the northern Everglades

Since the early 1900s, the Everglades have been influenced by anthropogenic actions including altered hydrology and increased nutrient loading. In the northern Everglades an apparent effect of these disturbances has been the development and proliferation of dense cattail ( Typha spp. ) stands in areas previously dominated by sawgrass ( Cladium jamaicense Crantz) and sloughs. Cattail cover, soil nutrient concentrations, topography and fire history were determined for the Holey Land and Rotenberger Wildlife Management Areas, located in the northern Everglades. These data were analyzed using multiple regression to assess the relative influence of fire, hydrology and soil nutrients on cattail abundance. Holey Land and Rotenberger were overdrained over recent decades which resulted in soil compaction and nutrient accumulation, illustrated by increased soil bulk densities and elevated nutrient storage. Average bulk densities were 0.13 g cm −3 for Holey Land and 0.22 g cm −3 for Rotenberger. Average total P (TP) stored in the surface 10 cm of soil in Holey Land and Rotenberger were 7 and 13 g m −2, respectively. In contrast, Everglades soils uninfluenced by nutrient enrichment and with less severe overdrainage have bulk densities of 0.07 g cm −3 and TP storage of 4 g m −2. Typically, elevated soil P concentrations have been considered a primary factor influencing cattail growth and distribution in the Everglades. With the apparent absence of P limitation in Holey Land and Rotenberger, cattail abundance was influenced by either fire or hydrology. Forty-six percent of the variation of cattail cover in Holey Land was explained by elevation, indicating that increased water depth and duration of flooding have a significant impact on cattail expansion. In Rotenberger, fire was the most influential factor, explaining 57% of the variation in cattail cover. Hydrology was the second most important factor limiting cattail abundance.

Characteristics of pelleted wheat middlings that affect summer storage (1998)

Pelleted wheat middlings samples were when pelleted WM are stored on-farm collected from four Kansas flour mills in through the summer months, many Kansas March, April, and May, 1997 to characterize producers have observed heating, which has their moisture content and bulk density as resulted in caking, discoloration, and loss of they would be purchased directly from the flowability (Blasi et al., 1997 Cattlemens mills by a livestock producer. The average Day Report of Progress, p 37). moisture content of pelleted wheat middlings was 14% as they left the mills but declined This study was initiated in March, 1997 during the spring to 13.6%. Pellets purto investigate the characteristics of pelleted chased from Kansas mills during the summer WM that relate to their storability, especially months are likely to contain 13.0 to 13.5% during summer months. Our objective was moisture. The average bulk density was to describe moisture and bulk density charapproximately 40 lb/ft , which is equivalent acteristics of the pelleted WM as they would 3

初期充填時における粉体嵩密度の静電気による制御可能性について

Today, the parts of computer and communication instrument are requested to be accurate and reliable. Many parts in instruments are ceramics and are produced via powder handling on the way of the ceramics manufacturing processes. In this case, the final performance of products are effected by the powder handling. First of all the bulk density of powder has some effects on sintered powder compact. This shows that even if chemical components are same, the final performance of products are different each other depending on bulk density.In this paper, the application of electrostatic effect on initial bulk density of powder in a cell is taken notice. And it is experimentally discussed using X-ray radiograph system. As the results, average equivalent bulk density at one point packing is pointed out to decrease as applied voltage increases, and at two point packing it keeps constant independent of electrostatic effect.

Preparation of nickel ferrite using the aerosolization technique

Abstract The aerosolization products obtained from aerosolization by atomization of 22 wt.% nickel nitrate and 23 wt.% ferric nitrate aqueous solutions as aerosolized separately were found to consist of hollow spheres. The characterization of these products revealed that the pyrolysis temperature affects the crystallinity, particle size, particle size distribution, specific surface area, average bulk density and decomposition efficiency of the product. The nickel nitrate aerosolization product was fired at 723, 843, 1013 and 1083 K. The decomposition efficiency at the previously mentioned temperatures was 63, 90, 95 and 96%, respectively. The X-ray results revealed that the aerosolization product of the nickel nitrate at 723 K consists of tiny NiO crystals and other non-crystalline phases, while those obtained at 843 K and higher consist of crystalline NiO. The aerosolization products of ferric nitrate as fired at 933 K and below this temperature were found to be non-crystalline, while those obtained at 1083 K were found to be crystalline. The average particle size was found to increase for all the products by increasing the decomposition temperature of the two nitrate aerosols involved in this investigation. The increase in particle size was attributed to the sintering of the powder particles. On the other hand, the surface area decreases by increasing the decomposition temperature.

Preparation of nickel ferrite using the aerosolization technique

In this part of the investigation, mixed raw materials' solution was subjected to aerosolization to obtain NiFe 2 O 4 powder. The final product was found to be hollow spheres. Depending on the pyrolysis temperature, the degree of crystallinity of NiFe 2 O 4 changes from non-crystalline ( T <753 K) to fully crystalline ( T >933 K). In addition, increasing the pyrolysis temperature was found to increase the average particle size, and lower the specific surface area and the average bulk density. The results also indicate that the concentration of the starting solution has an appreciable effect on the product characteristics, i.e. decomposition efficiency, average particle size, particle size distribution and amount of product.