Variation In Specific Gravity Research Articles

Wood specific gravity variation among five important hardwood species of Kashmir Himalaya.

Wood Specific Gravity (SG) is a measure of the amount of structural material a tree species allocates to support and strength. In the present study, specific gravity varied among the five different woods at three different sites from 0.40 in Populus nigra at site III (Shopian) to 0.80 in Parrotiopsis jacquemontiana at site II (Surasyar). Among the three different sites, specific gravity varied from 0.73 to 0.80 in Parroptiosis jacquemontiana; in Robinia pseudoacacia it varied from 0.71 to 0.79; in Salix alba, it varied from 0.42 to 0.48; In Populus nigra it varied from 0.40 to 0.48 and in Juglans regia it varied from 0.59 to 0.66. On the basis of the specific gravity variation patterns these woods were categorized as light (Salix alba, Populus nigra) moderately heavy (Juglans regia) and moderately heavy to heavy (Robinia pseudoacacia, Parrotiopsis jacquemontiana) which predicts their properties like strength, dimensional stability with moisture content change, ability to retain paint, fiber yield per unit volume, suitability for making particleboard and related wood composite materials and suitability as a raw material for making paper.

COMPARISON OF THE SPECIFIC GRAVITY VARIATION OF Swietenia macrophylla, Khaya senega/ens;s AND Pau/ownia fortunei

Since the existing natural forests have become increasingly subjected to conservationpressure, forest plantations have been recognized as an alternative to meet the future~demand for sawn timber. A major drawback for the efficient utilization and promotion ofnew species such as Khaya senegalensis and Paulownia fortunei as well as muchfamiliar Swietwnia macrophy/la is the lack of information regarding their woodproperties grown under local conditions. The present work was designed to determinespecific gravity of each species, investigate the variation of specific gravity within thespecies and to determine the effect of growth rate on specific gravity.Specific gravity variations were studied in 79 year old Swietwnia macrophylla, 49 yearold Khaya senegalensis and 16 year old and Paulownia fortunei trees. Three trees wereselected from each species and pith to bark variation was investigated in sample disksremoved at breast height, 50%' and 80% heights of the bole length. Radial variationswere studied at percentage distances from the pith.The mean numerical specific gravity values obtained for Swietwnia macrophylla. Khayasenega/ensis and and Paulownia fortunei were 0.511,0.617 and 0.317 respectively andthese values suggest that the values are comparable to those earlier published data forother countries. The results of this study indicate that general pattern of radial variationof specific gravity in both Swietwnia macrophylla and Khaya senegalensis was to remainuniform from pith to bark. This pattern was evident at all the height levels. In Paulowniafortune, the radial trend was to show a gradual increase from pith to bark at all the heightlevels. The axial trend of Swietwn!a macrophyl/a was higher specific gravity at the base,drops to a minimum at mid height and increase again to a maximum at merchantabletop. Khaya senegalensis showed a gradual increase from base to top. The axial variationwas not significant in both these species. and Paulownia fortunei showed a significantreduction of specific gravity from base to top.To investigate the effect of growth rate on specific gravity, sample disks were extracted atbreast height and ring width and whole ring specific gravity were measured based on thegrowth rings identified from pith to bark. Results indicated that no substantial anddefinite relationship appears to exist between whole ring specific gravity and ring widthrepresenting the growth rate in Swietwnia macrophyl/a. Khaya senegalensis (diffuseporous)and and Paulownia fortunei (ring-porous).

VARIATION OF SPECIFIC GRAVITY WITHIN Eucalyptus grandis TREES GROWING IN DIFFERENT SITE CLASSES.

Wood is a very remarkable material with variability and flexibility The variability of woodincreases its utility It may be also a major drawback to its efficient use as raw materialTherefore understanding of pattern of wood properties within the tree has becomeimportant. In addition, growth rate and its effect on wood properties are of practicalimportance to maximize wood and fiber production. In this study, variations of specificgravity within the trees of 30-years old Eucalyptus grandis extracted from Pattipola,Saruhipura and Piduruthalagala in Nuwara-Eliya districts were studied. Data werecollected in relation to site class (growth rate) as determined by tree height. The objectiveof the study was to find out whether specific gravity is affected by growth rate of tree.Specific gravity values were collected in a systematic manner, which are essential incommercial utilization of this species. Three sites, namely Slow Growth Site (SGS),Medium Growth Site (MGS) Fast Growth Site (FGS) were chosen. Five trees from eachsite were taken for the investigation. Tree height difference between SGS (33.8 meters )FGS (45 meters) was significantly different (PS:005) but not between SGS and MGS (387meters)Variation patterns of specific gravity in racial direction were studied using two linearsections extracted across the diameter of every sample disc, from north to south and cast towest at different height levels at breast height and at 20'Yo,40%, 60% and 80% of total treeheight. 3021 wood samples of 2*2* 1 em dimensions were used for specific gravitydetermination.In general, low specific gravity values were observed at pith in all three sites. In fastgrowth site, specific gravity increased from uith; thereafter it remained constant towardsthe bark with small fluctuation. In slow and medium growth sites, however specific gravityincreased gradually towards the bark. Fast growth site maintained the highest specificgravity values throughout piths to bark The specific gravity of SGS and MGS increasedrapidly with increasing distance from pith.In general, specific gravity increased with tree height in all sites except at 20% height levelin SGS and MGS. Mean specific gravity values in SGS at breast height, 20%, 40'%, 60'Y<,and 80% height levels were 0.432, 0.431, 0433, 0.468 and 0.475 respectively. Specificgravity values for these levels in MGS were 0.441,0.435,0.467,0.477,0.542 and Specificgravity values were 0.479.0.482,0.493,0525, .J.553 for FGS respectively.

MODEL FOR THE CORRECTION OF THE SPECIFIC GRAVITY OF BIODIESEL FROM RESIDUAL OIL

Biodiesel is a important fuel with economic benefits, social and environmental. The production cost of the biodiesel can be significantly lowered if the raw material is replaced by a alternative material as residual oil. In this study, the variation of specific gravity with temperature increase for diesel and biodiesel from residual oil obtained by homogeneous basic catalysis. All properties analyzed for biodiesel are within specification Brazil. The determination of the correction algorithm for the specific gravity function of temperature is also presented, and the slope of the line to diesel fuel, methylic biodiesel (BMR) and ethylic biodiesel (BER) from residual oil were respectively the values -0.7089, -0.7290 and -0.7277. This demonstrates the existence of difference of the model when compared chemically different fuels, like diesel and biodiesel from different sources, indicating the importance of determining the specific algorithm for the operations of conversion of volume to the reference temperature.

Prediction of on-line froth depth measurement errors in industrial flotation columns: a promising tool for automatic control

The pulp-froth interface position is important from a metallurgical point of view because it determines the relative importance of the cleaning and the collection zones. The pulp-froth interface position is measured based on variations of specific gravity, temperature or conductivity between the two zones to locate the pulp froth interface position. In this study, the pressure measurements are used to calculate the values of the froth layer height. These two meters are installed in the upper part of the column at 1.4 m and 2.4 m respectively, from the top of the column. Methods using pressure gauges are commonly used in industrial operations Even though their accuracy is limited (due to assumptions of uniformity of the pulp and froth density), and they always have some error. In the Sarcheshmeh copper industrial plant (Iran), a float was installed near the column with 2.5 m height that was calibrated to 5 cm intervals in order to determine the more exact forth height and compare it with the recorded froth height in control room. In this paper, an algorithm based on Kalman Filter is presented to predict on-line froth height errors using two pressure gauges. This research is based on the industrial real data collection for evaluating the performance of the presented algorithm. The quality of the obtained results was very satisfied. The RMS errors of prediction froth height errors was less than 0.025 m.

Perioperative Therapeutic Plasmapheresis

Perioperative Therapeutic Plasmapheresis

Segregação do lenho de nogueira-pecã (Carya illinoinensis) pela variação radial da massa específica básica

This study aimed to estimate the age of segregation of juvenile and adult wood of walnut-pecan ( Carya illinoinensis ) by the radial specific gravity variation. A total of 10 mature trees were collected from two physiographic regions of the Rio Grande do Sul State, Brazil, being five trees from each region. A disc, with approximately 2 cm thick, was removed from each tree at 10 cm trunk height. A central portion of 2 cm in width was removed from each disc and this central portion was divided into two samples. Specimens measuring 1 x 2 x 2 cm were made, each in the radial direction of the disc, which were used to determinate the specific gravity and thus estimate the age of segregation of adult and juvenile wood of walnut-pecan. The segregation age was 12 years. However, the radial variation in specific gravity was not a great parameter to determine the segregation age of wood.

Testing a Novel Method to Approximate Wood Specific Gravity of Trees

Wood specific gravity (SG) has long been used by foresters as an index for wood properties. More recently, SG has been widely used by ecologists as a plant functional trait and as a key variable in estimates of biomass. However, sampling wood to determine SG can be problematic; at present, the most common method is sampling with an increment borer to extract a bark-to-pith core—a difficult task requiring considerable physical effort and sometimes repeated borings to hit the pith, with potential to damage the trunk of small trees. Here, we test a novel sampling method that reduces the effort to obtain an adequate increment core and results in less wood extracted from the tree. The Wiemann approximation predicts the point along a radius at which the wood SG equals the disk cross-sectional SG. When SG changes linearly across the radius, the point of approximation is at two-thirds of the radial distance. As a test, we compare SG at various points along the radius with the true SG of the disk. At all points except the point of approximation (i.e., at two-thirds of the radial distance), wood SG differed significantly from the true cross-sectional mean SG, whereas at two-thirds of the radial distance, the wood SG did not differ significantly from the tree mean SG for a group of 128 tropical trees and 25 temperate trees that had been sampled bark to pith. Overall, the method shows promise in that wood SG of a tree may be estimated accurately and without bias by boring the tree only to the point of approximation, that is, one-sixth of the trunk diameter. However, boring to one-sixth of the diameter provides an unbiased estimate of SG only if radial variation in SG is a linear function of radial distance. A limitation of the method is that an initial subsample of trees must be bored to determine the pattern of radial variation in a species before the approximation can be applied to other individuals.

Idade de segregação do lenho juvenil e adulto pela variação da massa específica de açoita-cavalo

O presente trabalho teve como objetivo estimar a idade de segregação do lenho de Luehea divaricata Mart. (açoita-cavalo) por meio da variação radial da massa específica. Para o desenvolvimento do estudo, foram coletadas dez árvores de duas regiões do Estado do Rio Grande do Sul. Foi retirado um disco por árvore, com aproximadamente 2cm de espessura a 0,10m de altura do tronco. De cada disco, retirou-se, com auxílio de uma serra-fita, uma bagueta central de 2,0cm de largura, bem orientada no sentido radial, incluindo a medula no centro, dividiu-se então a bagueta em duas amostras "A" e "B". A massa específica foi obtida da relação entre peso seco e volume úmido. O volume úmido foi determinado de acordo com a norma ASTM D 2395 - 93, 1995. A segregação dos lenhos foi encontrada por regressão linear simples dos dados de variação da massa específica no sentido medula-casca. Foi feita uma regressão linear na faixa crescente dos dados e outra na faixa decrescente. A intersecção das retas extrapoladas foi adotada como idade de segregação. Os resultados obtidos mostraram que o lenho de açoita-cavalo segrega em aproximadamente 26 anos para a região da Depressão Central e 23 anos para a região da Encosta Superior do Nordeste. Nos dados de variação de massa específica, foi feita uma análise de variância multifatorial. Constatou-se que há diferença significativa entre lenhos e entre regiões. Por outro lado, as amostras A e B de cada árvore não foram estatisticamente diferentes entre si.

Characterisation and categorisation of the diversity in viscoelastic vibrational properties between 98 wood types

Increased knowledge on diversity in wood properties would have implications both for fundamental research and for promoting a diversification of uses as material. The objective is to contribute to overcoming the critical lack of data on the diversity of wood dynamic mechanical/viscoelastic vibrational properties by testing lesser known species and categorising sources of variability. Air-dry axial specific dynamic modulus of elasticity (E′/γ) and damping coefficient (tanδ) were measured on a wide sampling (1,792 specimens) of 98 wood types from 79 species. An experimental device and protocol was designed for conducting systematic (i.e. rapid and reproducible) characterisations. Diversity at the specimens’ level corroborates the “standard” relationship between tanδ and E′/γ, which is discussed in terms of orientation of wood elements and of chemical composition. Diversity at the species level is expressed on the basis of results for normal heartwood, with specific gravity (γ) ranging from 0.2 to 1.3. Axial E′/γ ranges from 9 to 32 GPa and tanδ from 4 × 10−3 to 19 × 10−3. Properties distribution follows a continuum, but with group characteristics. The lowest values of tanδ are only found in certain tropical hardwoods. Results can also suggest alternative species for musical instruments making. The variations in specific gravity, in stiffness or in “viscosity” appear to be predominantly linked to different levels of diversity: between species or between wood types (reaction wood or taxonomy-related differences in heartwood extractives).

Forest Management, Engineering, and Operations / Global Competency and Issues in Contemporary Education

Abstract 31Maps depicting spatial variation in wood properties are important for forest product industries as they aid decision making regarding raw material procurement, can assist in product categorization and help improve utilization. Loblolly pine is an important commercial species grown throughout the southern Unites States of America (USA). Wood Quality Consortium (WQC)—a joint collaboration between the University of Georgia, USDA Forest Service and industries—was established in 1999 with the objective of characterizing wood property variation of plantation grown loblolly pine. Data on wood specific gravity (SG), modulus of elasticity (MOE) and modulus of rupture (MOR) collected by the WQC was utilized in this study. Maps showing spatial variation in SG at different stand ages and SG, MOE and MOR at different heights within a tree were developed using appropriate spatial prediction methods (kriging). The geographical variation of these wood properties across southeastern USA was demonstrated here.

Comparative studies on biochemical and cytological constituents of synovial fluids in some farm animals

The goal of the present study was to evaluate the difference in the synovial fluid constituents in cattle, buffaloes, camels, and donkeys. A total number of 20 clinically healthy adult male animals (cattle (N = 5), buffaloes (N = 5), camels (N = 5), and donkeys (N = 5) were subjected to study. Synovial fluid samples were collected from the metacarpophalangeal joint under complete aseptic conditions. The samples were examined physically, cytologically, and biochemically. Synovial fluid analysis revealed significant variations in specific gravity, total leukocyte counts, total proteins, albumin, globulins, glucose levels, and alkaline phosphatase activity among investigated animal species.

Deconvolution problem in inertial gravimetry

The method for extraction of a slowly varying signal (gravity variations) from an additive mixture of the useful signal and noise, with noise substantially exceeding the measured variations of specific gravity, is discussed. The principal problem is the exclusion of errors related to dynamical characteristics of gravimeters. An alternative to the well-known Kalman filter is proposed.

Modeling the longitudinal variation in wood specific gravity of planted loblolly pine (Pinus taeda) in the United States

Loblolly pine (Pinus taeda L.) is a major plantation species grown in the southern United States, producing wood having a multitude of uses including pulp and lumber production. Specific gravity (SG) is an important property used to measure the quality of wood produced, and it varies regionally and within the tree with height and radius. SG at different height levels was measured from 407 trees representing 135 plantations across the natural range of loblolly pine. A three-segment quadratic model and a semiparametric model were proposed to explain the vertical and regional variations in SG. Both models were in agreement that a stem can be divided into three segments based on the vertical variation in SG. Based on the fitted models, the mean trend in SG of trees from the southern Atlantic Coastal Plain and Gulf Coastal Plain was observed to be higher than in other physiographical regions (Upper Coastal Plain, Hilly Coastal Plain, northern Atlantic Coastal Plain, and Piedmont). Maps showing the regional variation in disk SG at a specified height were also developed. Maps indicated that the stands in the southern Atlantic Coastal Plain and Gulf Coastal Plain have the highest SG at a given height level.

A new predictive model of lifter bar wear in mills

The cost of mill relining and the influence of the liner profiles on mill performance provide a strong motivation to improve liner selection. However, the capability to predict liner life and progressive profile is poorly developed in the industry. A new model has been developed to predict the rate of liner wear based on the main parameters affecting the wear process such as; ore type, relative velocity between the ore and the liners, liner hardness and friction conditions. The resultant model is capable of determining the wear as a function of mill operating and discharge conditions based on the variation of specific gravity of mill contents, geometrical characteristics of the mill and mill velocity. The results from this model are in good agreement with the measured data from the SAG mill at Sarcheshmeh Copper Complex, Iran.

Electric resistivity tomography shows radial variation of electrolytes in Quercus robur

Electric resistivity tomograms of English oak ( Quercus robur L.) show a very distinct pattern of electric resistivity that has not been found in any other tree species yet and that cannot be related to the distribution of wood moisture content over the stem cross section. To reveal the factors underlying this two-dimensional pattern of electric resistivity, the variation of specific gravity and wood moisture content was analyzed in 18 cross sections of six roadside English oak trees after electric resistivity tomography. pH and electrolyte content were analyzed in two representative cross sections. Results show that electric resistivity correlates neither with wood moisture content nor density. The steep increase in electric resistivity at the sapwood–heartwood boundary correlates well with decreasing pH, potassium, and magnesium. The decreasing electric resistivity within the heartwood of English oak correlates with potassium and magnesium, increasing from the sapwood–heartwood boundary to the pith. More research is needed to identify species-specific electric resistivity patterns and their main factors if the method is to be used to detect wood fungal decay, historical ground water contamination, or other influences that may change the pattern of electric resistivity in the stem cross section.

In-line estimation of sulfur and nitrogen contents during hydrotreating of middle distillates

The main objective of this work is analyzing whether it is possible to develop an empirical correlation for in-line estimation of the sulfur and nitrogen contents of the middle distillates Hydrotreating (HDT) products for control purposes. Correlations are based only on readily available in-line information of specific gravity variation between feedstock and products, without considering any piece of information about the kinetic behavior of the catalyst. Experimental data were obtained in pilot plants under operating conditions that are representative of refinery operations. Results indicate that the removal of nitrogen and sulfur compounds during middle distillates HDT can be monitored in-line in real time, based on the available measurements of specific gravity. This allows for development and implementation of advanced in-line procedures for monitoring and control of the HDT process in real time.

Radial and axial variation in specific gravity and anatomical properties of plantation grownEucalyptuscitriodoraHook

Radial and axial variation in specific gravity and certain anatomical properties were investigated in twenty year old plantation grown Eucalyptus citriodora Hook. Specific gravity and certain anatomical properties varied significantly in both directions. Average specific gravity ranged from 0.666 to 0.711 pith outwards and 0.762 to 0.728 base upwards; average fibre length ranged from 1062 μm to 1301 μm and 1211 μm to 1166 μm in radial and axial directions respectively. Similarly vessel diameter showed a range of 112 μm to 151 μm radially and 118 μm to 141 μm axially; vessel element length ranged from 405 μm to 505 μm in radial direction and 428 μm to 461 μm in axial direction. Although the fibre diameter, fibre lumen diameter and wall thickness showed significant variation, the differences in their values were found to be minor. Maximization of parameters was taking place after 75% of radial distance for specific gravity and fibre length. Based on general features, physical properties and anatomical structure, the wood can be used in furniture and handicraft industries.

Required minimum granule size in UASB reactor and characteristics variation with size

The objective of this study was to define minimum size of bioparticles that could be classified as granules, to offer all advantages of granular sludge. Based on the theory of sedimentation, the minimum diameter bioparticles, which should be considered as granules was found out for specific gravity of sludge ranging between 1.01 and 1.05. For example, for specific gravity of 1.035 the minimum diameter of granules required for better sludge retention was 0.34 mm. The diameter based on this theory was evaluated by carrying out settling column analysis of a granular sludge obtained from lab-scale UASB reactor and verified with microscopic observation. To find out the effect of granules size on the nature of biodegradability, specific methanogenic activity (SMA) was carried out. It was observed that SMA increased with size of bioparticles tested in the range of 0.27–3.03 mm. The change in VSS/SS ratio and specific gravity was observed with size of granules. Consideration of variation in specific gravity with size of granules increased the degree of validation of sedimentation theory for the calculation of granules diameter.

Investigation of the nonuniformities in polyurethane chemical mechanical planarization pads

We have investigated the spatial variation of specific gravity (nonuniformities) in full size commercial pads for chemical mechanical polishing using a previously described nondestructive ultrasound transmission (UST) technique. After UST analysis, the different regions showing relatively higher and lower ultrasound permeability, which directly correlates with material density, were isolated and subjected to further evaluation of their mechanical properties using dynamic mechanical analysis (DMA) and tribological properties using a bench top chemical mechanical planarization (CMP) tester. Though the evaluated regions did not show significant variation in their tribological properties, presence of such regions in the body of the polishing pads has the potential to induce intermittent process defect during the CMP process.